• TABLE OF CONTENTS
HIDE
 Front Cover
 Table of Contents
 Eric M. Stuve of the University...
 Tulane: Katrina and its afterm...
 Design projects of the future
 A whole new mind for a flat...
 The next millennium in chemical...
 A vision of the curriculum of the...
 Teaching engineering in the 21st...
 A different chemical industry
 Crystal engineering: From molecules...
 Inside the cell: A new paradigm...
 Energy consumption vs. energy...
 Gas permeation computations with...
 Back Cover






























Chemical engineering education
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Title: Chemical engineering education
Alternate Title: CEE
Abbreviated Title: Chem. eng. educ.
Physical Description: v. : ill. ; 22-28 cm.
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Creator: American Society for Engineering Education -- Chemical Engineering Division
Publisher: Chemical Engineering Division, American Society for Engineering Education
Place of Publication: Storrs, Conn
Publication Date: Spring 2006
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Additional Physical Form: Also issued online.
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Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Table of Contents
        Page 73
    Eric M. Stuve of the University of Washington
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
    Tulane: Katrina and its aftermath
        Page 80
        Page 81
        Page 82
        Page 83
        Page 84
        Page 85
        Page 86
        Page 87
    Design projects of the future
        Page 88
        Page 89
        Page 90
        Page 91
        Page 92
        Page 93
        Page 94
        Page 95
    A whole new mind for a flat world
        Page 96
        Page 97
        Page 98
    The next millennium in chemical engineering: Introduction
        Page 99
        Page 100
        Page 101
        Page 102
        Page 103
    A vision of the curriculum of the future
        Page 104
        Page 105
        Page 106
        Page 107
        Page 108
        Page 109
    Teaching engineering in the 21st century with a 12th-century teaching model: How bright is that?
        Page 110
        Page 111
        Page 112
        Page 113
    A different chemical industry
        Page 114
        Page 115
    Crystal engineering: From molecules to products
        Page 116
        Page 117
        Page 118
        Page 119
        Page 120
        Page 121
        Page 122
        Page 123
        Page 124
        Page 125
    Inside the cell: A new paradigm for unit operations and unit processes?
        Page 126
        Page 127
        Page 128
        Page 129
        Page 130
        Page 131
    Energy consumption vs. energy requirement
        Page 132
        Page 133
        Page 134
        Page 135
        Page 136
        Page 137
        Page 138
        Page 139
    Gas permeation computations with Mathematica
        Page 140
        Page 141
        Page 142
        Page 143
        Page 144
    Back Cover
        Back Cover 1
        Back Cover 2
Full Text

CEI
VOLUM 40NMER2SRIG20










INVITED GUEST EDITORIAL


For the sake of argument-


If the conventional lecture is dead,

why is it alive and thriving?


Don Woods, CEE Publications Board


Straight lecturing is the least effective way to im-
prove student learning. Students tend to remember 10
to 50% from "passive" involvement in the learning
process (we remember about 10% of what we read;
20% of what we hear; 30% of what we see; and 50%
of what we hear and see). Students remember 70 and
90%, however, if they are "actively" involved (we re-
member about 70% of what we say and 90% of what
we say and do). Also, students in learning environ-
ments where lecturing dominates become more "rote
learners"; students learning in problem-based or co-
operative learning environments become more
"deep learners."
Recently, research was done on the effectiveness of
updating courses for medical doctors. Those courses
that were lectures produced no change in practice.
Courses that included active learning components did
produce a change in practice.
Since we usually want to help students remember
and since we want graduates who are deep learners
instead of rote learners, why do faculty still give 50-
minute lectures of teacher talk? Why do universities
build more lecture auditoriums-instead of flat-floor
learning environments with movable chairs and tables
that are more conducive to cooperative and active
learning? Why do courses in teacher training focus on
"how to lecture," and "how to lecture to large classes,"
instead of "how to use active learning, cooperative
learning, or problem-based learning?" Why are fac-
ulty called "lecturers"?
Perhaps the answer is that lecturing is relatively easy,
most of us "learned" from lectures (so what's wrong
with the lecture?), and each of us gets a sense of power
and usefulness when we walk into a "lecture hall" and
all eyes look at us and wait to write down our every


thoughts. Perhaps that's the only way that we see that
we can cover the material-but our role is to uncover
material so that students learn. Perhaps we don't want
to stop lecturing even though we know there are other
options available.
So if I currently use straight lectures, what might I
do? One simple way to change from straight lecturing
to more effective learning environments is to never
have more than 20 minutes of teacher talk. Boredom
sets in after 20 minutes. A suggestion is to use a timer
set for 20 minutes to remind you to shift from "teacher
talk" to some activity.
Examples of "active" activities include:
Ask individuals to write reflections (2 min.)
then discuss with a neighbor (90 sec.)
Have students turn to their neighbor and say:
"Did you understand that?"
"Do you believe that?"
"The key point so far is ..
"A practical application of this
stuff is ...."
Ask students to compare or rework notes
Use Talk Aloud Pairs Problem Solve, or
TAPPS

Other options include using "rounds" (where stu-
dents sit in circles of about four or five and each com-
ments for about 30 seconds on a topic you pose) or
using cooperative learning groups.
The straight lecture with 50 minutes of teacher talk
really doesn't improve student learning. It's time to
change. 1













EDITORIAL AND BUSINESS ADDRESS:
Chemical Engineering Education
Department of Chemical Engineering
University of Florida Gainesville, FL 32611
PHONE and FAX : 352-392-0861
e-mail: cee@che.ufl.edu

EDITOR
Tim Anderson

ASSOCIATE EDITOR
Phillip C. Wankat

MANAGING EDITOR
Lynn Heasley

PROBLEM EDITOR
James 0. Wilkes, U. Michigan

LEARNING IN INDUSTRY EDITOR
William J. Koros, Georgia Institute of Technology

-PUBLICATIONS BOARD
CHAIRMAN *
E. Dendy Sloan, Jr.
Colorado School of Mines
VICE CHAIRMAN
John P. O'Connell
University of Virginia

MEMBERS
KristiAnseth
University of Colorado
Pablo Debenedetti
Princeton University
Dianne Dorland
Rowan University
Thomas F. Edgar
University of Texas at Austin
Richard M. Felder
North Carolina State University
Bruce A. Finlayson
University of Washington
H. Scott Fogler
University of Michigan
Carol K. Hall
North Carolina State Universit'
William J. Koros
Georgia Institute of Technology
Steve LeBlanc
University of Toledo
Ronald W. Rousseau
Georgia Institute of Technology
Stanley I. Sandler
University of Delaware
C. Stewart Slater
Rowan University
Donald R. Woods
McMaster University


Chemical Engineering Education


Volume 40


Number 2


Spring 2006


> DEPARTMENT
80 Tulane: Katrina and its Aftermath,
Brian S. Mitchell, John A. Prindle, Henry S. Ashbaugh, Vijay T. John


> EDUCATOR
74 Eric M. Stuve of the University of Washington, Bruce A. Finlayson


> CURRICULUM
88 Design Projects of the Future,
Joseph A. Shaeiwit:, Richard Turton

132 Energy Consumption vs. Energy Requirement,
L.T. Fan, Tengyan Zhang, John R. Schlup


> CLASS AND HOME PROBLEMS
140 Gas Permeation Computations with Mathematica,
Housam Binous


> RANDOM THOUGHTS
96 A Whole New Mind for A Flat World, Richard M. Felder


> THE NEXT MILLENNIUM IN CHEMICAL ENGINEERING
99 Introduction,
Christine M. Hrenya, H. Scott Fogler

104 A Vision of the Curriculum of the Future,
Robert C. Armstrong

110 Teaching Engineering in the 21st Century with a 12th-Century
Teaching Model: How Bright Is That?
Richard M. Felder

114 A Different Chemical Industry,
E.L. Cussler

116 Crystal Engineering: From Molecules To Products,
Michael F. Doherty

126 Inside the Cell: A New Paradigm for Unit Operations and Unit
Processes?
Jerome S. Schultz


CHEMICAL ENGINEERING EDUCATION (ISSN 0009-2479) is published quarterly by the Chemical Engineering
Division, American Society for Engineering Education, and is edited at the University of Florida. Correspondence
regarding editorial matter, circulation, and changes of address should be sent to CEE, Chemical Engineering Department,
University of Florida, Gainesville, FL 32611-6005. Copyright 2006 by the Chemical Engineering Division, American
Society for Engineering Education. The statements and opinions expressed in this periodical are those of the writers and not
necessarily those of the ChE Division, ASEE, which body assumes no responsibility for them. Defective copies replaced if
notified within 120 days of publication. Write for information on subscription costs andfor back copy costs and availability.
POSTMASTER: Send address changes to Chemical Engineering Education, Chemical Engineering Department, University
of Florida, Gainesville, FL 32611-6005. Periodicals Postage Paid at Gainesville, Florida, and additional post offices.


Spring 2006










educator


Eric M. Stuve


of the University of Washington



BRUCE A. FINLAYSON i
University of Washington -
Seattle, WA 98195-1750 as .


watches the Indianapolis 500 race. That's
a legacy from growing up in Indiana.
He was born in Montana, but soon afterward
his parents moved the family to the Midwest, liv-
ing in Michigan, Wisconsin, and Indiana. It's
typical of Eric that he retained his affection for
that down-home pastime even as he embraced the
intellectual challenges of studying the sciences and
pursuing a professorial career. Eric has always been
one to run his own race.


Since he was living in Milwaukee as a high-
school senior, attending the University of Wis-
consin, Milwaukee, was a natural choice. After
one year, and upon the advice of Charles G. Hill,
he transferred to the Madison campus, where he
excelled. In preparing for graduate school, Eric
was fortunate to receive good advice from the
Wisconsin professors. Ed Lightfoot reviewed fac-
ulty at a number of schools and Hill, for whom
Eric was doing an undergraduate research project,
cautioned about getting involved in surface science as it was
a lot of ultrahigh vacuum physics. It was good advice, but
Eric had other plans.
Eric's research began at Stanford, where he worked with
Bob Madix on surface reactions in ultrahigh vacuum on plati-
num and silver. He found the physics was fun. Following his
Ph.D. (1984) he went to Berlin with an Alexander von
Humboldt Fellowship in the Fritz-Haber-Institut der Max-
Planck-Gesellschaft, and it was in Berlin that he met Monika,
who was born and raised in East Germany. They wed in 1985,
which was also the year Eric came to the University of Wash-


ington, where he is now chair of the Department of Chemical
Engineering.
Eric is committed to involving students in innovative
projects in both design and research, and he brings consider-
able enthusiasm, humor, and a fundamental understanding to
all his interactions with the students.

TEACHING AND RESEARCH
With Eric, teaching and research are inseparable. Learning
by teaching has served him well. He reports that, in his first
year teaching the process design course, he learned to put


Copyright ChE Division of ASEE 2006
Chemical Engineering Education



































into perspective what he did at the molecular level, helping
him as an educator and researcher. Likewise, teaching his
first course in graduate thermodynamics challenged him to
make the homework problems relevant-and he suddenly saw
how he could bring electrical engineering and chemical en-
gineering to the course. Furthermore, he says, he had one of
those eureka moments: "I could do this."
Thus spawned his work on high electric fields, which ran
for 10 years and provided important data no one else had: A
field ion microscope was used to study field-induced surface
chemistry at very high electric fields (100 MV/cm); adsorp-
tion and reaction of water on sharp (10-100 nm) field emitter
tips elucidated the basic ionization of water to hydronium
ions and hydroxide ions induced by the electric field and the
structure of water at the interface. This information is useful
for rational catalyst design for fuel cells, understanding ice
chemistry in oceanic and atmospheric environments (ozone
hole chemistry), and development of ultra-capacitors for high-
energy/high-power electrical devices.
As he began his research at the University of Washington,
Eric branched out into electrochemical problems as well, pro-
viding the underlying support for his later work on fuel cells.
While in Berlin, he had learned how to apply electrochemi-
cal concepts to surface reactions on metal electrodes immersed
in liquids. He then built equipment that enabled comparison
of electrochemical and gas-solid surface phenomena under
nearly identical conditions. This helped elucidate the impor-
tance of potential in reactions at the fluid-solid interface. The
electrode surfaces could be analyzed using thermal desorp-
tion, low-energy electron diffraction, Auger and X-ray photo-
electron spectroscopy, and secondary ion mass spectrometry.
For his work, Eric was chosen as an NSF Presidential Young
Spring 2006


Eric and three very happy grads
let loose with some leis follow-
ing commencement ceremonies
on campus.







Investigator. Since his work was mostly
done under high vacuum, he joined the
American Vacuum Society (AVS) and, over
time, became a director, trustee, and chair
of the Investment Advisory Committee. In
his work with investments, he taught the
other scientists the concept of net present
value, which-fittingly for Eric-he had
learned by teaching the undergraduate de-
sign course. He is currently a fellow of the AVS.

FUEL CELL LOCOMOTIVE
One day Eric and a professor from Aeronautics and Astro-
nautics (Reiner Decher) came to see me in the chair's office.
They proposed making a fuel-cell driven locomotive, amuse-
ment park size.
Eric's interest was in the fuel cell, and Reiner's passion
was with trains. They explained that combining the efficiency
of a train for transporting goods with the efficiency of a fuel
cell would make an ideal system. As we talked, the image of
having a small train circle Frosh Pond during Engineering
Open House came to mind as a great crowd pleaser. Ex-
cept . the thought of inexperienced undergraduates han-
dling hydrogen in a venue with thousands of middle school
kids was a scary one, to say the least.
But Eric was undeterred, and had other ideas as well. Thus
through his determination and vision was born one of the
country's best centers for fuel cell education, now encom-
passing several professors and several courses-undergradu-
ate and graduate, one of which is delivered as televised dis-
tance learning.
The goal of the Fuel Cell Locomotive Project (which be-
gan in 1996) was to produce a fuel cell system, fully con-
tained, that could provide 10 kW of power at 100 V to a pro-
ton exchange membrane system. The fuel cell would be the
prime mover for an 18-inch-gauge locomotive (one-third size)
that would pull two passenger coaches.
Eric's plan to demonstrate the train setup at an Engineer-
ing Open House got the green light, and it became a com-
bined project involving students and faculty from many dis-
75








































ciplines and two universities: the fuel cell chemistry inter-
ested chemical engineers; the special materials interested ma-
terials science students; the manufacturability interested me-
chanical engineers; and the applications interface interested
electrical engineers. Through an NSF program, students at
Penn State were also involved (in the 1997-98 school year).
The students worked in groups, which required the develop-
ment of communication skills and experience with teamwork.
It marked probably the first time these students had been ex-
posed to peer evaluation. It was also the first time most chemi-
cal engineering students came in close contact with students
in other disciplines, at least at a high, working level. A key
driving force that made the project fun was that it required
the "hands-on" design of a complex system.
The chemical engineering and materials science students
learned how to make and optimize a single cell, and then the
chemical engineering students joined the mechanical engi-
neering students to make a "stack," or several single cells
connected in electrical series. This task required designing
the flow field plates and seals, and dealing with the ever-
present safety concerns. Along the way students built sev-
eral versions of fuel cell test stands, ranging from small
to large scale.
Eric's role as project leader was to integrate all these disci-
plines and coordinate with faculty in other departments. It
involved a degree of risk since the outcome wasn't certain at
the beginning, but Eric kept a global view and ensured that
students learned something at each stage. While the mechani-
76


cal engineers were way ahead in building the rolling stock
for the train, the chemical engineers were learning that it is
hard to build a fuel cell. The fuel cells worked, but they didn't
provide enough power. Eric had the foresight to have stu-
dents each quarter build on what was learned the previous
quarter and improve it. In that way, progress was consistent
and the students had a feeling of success in achieving their
team goals.
As to my imagined fears at the outset, it turns out there was
only one explosion (no injuries). And for good measure, the
students were led through subsequent safety procedures to
see that there was never another.
On top of his success in bringing the idea to fruition, Eric
also learned how to guide such a project and avoid the end-
of-quarter rush, which is very important to those schools still
on a 10-week quarter system. In evaluating the experience,
Eric says, "Students are over-confident and under-experi-
enced." He notes the biggest problems were communication
(as in the real world) and time management (as in the real
world), but he was surprised at what they could do. The course
is definitely good preparation for work after school!
By 1999, under Eric's steady steering, the little train project
had gone from "I think I can, I think I can," to "I know I can,
I know I can."

FUEL CELL COURSES
The classroom program began to blossom when Eric asked
to teach his new fuel cell course on TV. I had been encourag-
ing faculty to present more of their specialty courses on TV
so that they could be taken by engineers who couldn't come
to campus. When Eric committed to giving it a try, we had to
rearrange the teaching schedule, with some faculty doubling
up to cover his previously assigned load, but we managed
and the course was a great success. Engineers in fuel cell
Chemical Engineering Education















As evidence of Eric's inner
drive, he insists on maintaining
his regimen of bicycling to work
even in one of the rainiest
months in Seattle's history. It
takes more than a few rain-
drops and puddles to steer
these wheels off course.


companies on both coasts took the course on TV, and ap-
proximately 160 University of Washington students and 85
distance-learning students have taken the course since 1998. It
also has been offered as a professional short course at three
national meetings of the Electrochemical Society.
With all this experience to bank on, Eric was able to part-
ner with colleague Dan Schwartz and get funding from the
Dreyfus Foundation to integrate fuel cells into the chemical
engineering curriculum. They put a fuel cell in the unit op-
erations laboratory and created new courses. Eric had already
partnered with Chevron, Apple Computer, and Boeing to pro-
vide a high-vacuum device for the undergraduate unit opera-
tions laboratory, where the students investigated Knudsen flow
in conditions pertinent to the electronics industry. But Eric
isn't satisfied with having students make things without also
understanding them.
Two classes were developed, one a course for juniors in
science and engineering (and for fuel cell professionals) and
the second a more rigorous course for seniors. As with all his
courses, Eric makes good use of PowerPoint slides that are
colorful and appeal to students for later viewing. They also
make it possible for Eric's graduate students to teach the class
as a distance-learning course (as part of a Huckabay Teach-
ing Fellowship).
Students frequently take the courses because of their de-
sire to contribute to improving society. They often report that
after the course, they appreciate how hard it is to make a fuel
cell system work, and they also are perceptive in seeing the
potential of fuel cells and recognizing that the public doesn't
understand where the hydrogen is coming from. Since Eric


attends conferences during the quarter, he comes back with
real-life examples of fuel cells that demonstrate to the stu-
dents that these are current topics and not just classroom les-
sons. As one student put it, "They are cool, very modern."
Lessons learned in the Fuel Cell Locomotive Project are
applied in the fuel cell courses, too: design projects involve
working with professors and other students, and developing
a fuel cell system that incorporates constraints of size and
functionality for real-life situations. As the courses proceed
from year to year, the projects change to reflect what was
learned previously. Since Eric is also now chair of the de-
partment, he shares the teaching load with Professors Dan
Schwartz and Stuart Adler. The fuel cell curriculum has grown
to include three faculty members and several courses. At the
undergraduate level are Introduction to Fuel Cells, Fuel Cell
Engineering, and Solid Oxide Fuel Cells. Courses at the gradu-
ate level are oriented to the scientific questions raised by fuel
cells and other reactions on surfaces: Thin Film Science, En-
gineering, and Technology; Reactions at Solid Surfaces; and
Electrons at Surfaces.
For Eric, the education program is a big part of his driving
force. He says, "If we can't work with students, I don't see
why we're here."
As a result of their experience in fuel cell projects, designs,
and courses, many of our graduates have gone to work for
fuel cell companies. Some were apprehensive about inter-
viewing with such companies, saying, "But our fuel cell didn't
work very well." In the course of their interviews, they found
out that the companies' fuel cells didn't always work well
either-and were hired!


Spring 2006










REACHING OUT TO GRADUATE STUDENTS
Befitting his individualist nature, when graduate students
start to work in Eric's lab, the first assignment he gives them is
to watch the film Dr. Strangelove. It's his habit to advise his
students on books to read, music to listen to, and movies to see.
After broadening the students' outlook on research, it's time
to get down to work. New students quickly learn Eric's man-
tra for reading a technical
paper is to read from left
to right, stop at the end of
each line, then see that you
understand it before going
on to the next one. He has
new students read three to
four papers, discuss them,
and write a research pro-
posal. This exercise sharp-
ens their critical thinking
skills and illustrates that the
generation of new knowl-
edge requires thought and
hard work.
Students then begin
working on a problem in
his lab, possibly using the A look inside
high-vacuum surface sci-
ence equipment. As the work nears the point of publication, a
draft is submitted, but it comes back covered in red ink. The
laboratory holds a copy of Fowler's Modern English Usage,
and students are expected to use it. Papers from Eric's labo-
ratory don't have author lists as long as the abstract; you are
expected to do the work yourself. As you might expect, some
of his graduate students are getting a chemistry degree, and
he teaches those students chemical engineering principles,
too; he thinks everyone should know them! Eric believes in
thorough preparation. His students are prepared for the fu-
ture by writing and rewriting papers, and by presenting the
work at conferences, always with a fundamental look at the
problem. As you'd expect, Eric's Ph.D. students work pre-
dominately in companies dealing with fuel cells, electrochem-
istry, and surface science (see Table 1).

LAUNCHING A LAB
Sometimes a researcher will look around for a problem that
can be solved with techniques and instruments he/she has
available. Not Eric. He sees a problem and thinks how best
to solve it, then proceeds. It was in this fashion that he built
up his laboratory equipment to be the extensive lab that it is
today (see Table 2). The philosophy does require creativity,
though, since it often means learning a new area that one
hasn't formally studied. Thus, the effects of high electric
fields, ceramics (and solid oxide fuel cells), and linear
density functional theory were things he learned in re-
78


e Er


sponse to particular problems.
One example of this philosophy in action is how Eric's
group was able to resolve a scientific argument. The back-
ground involves a focus of current research: namely, to de-
termine the reaction mechanisms that occur at surfaces. A
major application is direct methanol fuel cells (DMFC) for
portable power and low-power applications. Teasing out the
mechanism for the oxidation of
methanol on platinum and plati-
num plus ruthenium requires
careful work, often under high
vacuum. Yet, the understanding
is essential if DMFCs are to
become widespread. Begin-
ning with the Langmuir-
Hinshelwood surface reac-
tions, mechanisms are proposed
and then experiments designed
to determine the rate-controlling
steps. Some researchers felt the
reaction followed a parallel path,
while others insisted it was a
serial path. By elucidating four
different controlling rates of re-
action, Eric's group was able to
ic's lab. determine that the previous find-
ings in favor of the series path
were the result of reaction conditions and catalyst modifiers
(e.g., ruthenium). Both sets of reactions are necessary, but
local conditions determine which ones apply in any given
situation.
Since fuel cells operate at temperatures above room tem-
perature, Eric conducts studies at higher temperatures, too.
More recently, work on solid-oxide-supported platinum cata-
lysts supports the goal of fuel cells that run on diesel or other
hydrocarbon fuels without having to reform the fuel to pro-
duce hydrogen. Copper-ceria electrocatalysts minimize car-
bon formation, thus avoiding the problems of nickel-based
electrocatalysts. Solid oxide fuel cells have strong potential
for use in transportation, defense, and industrial and residen-
tial applications.
The fundamentals of surface science have widespread ap-
plication in other fields, too. The power of fundamentals was
brought home to me one day when I was reading a paper
about how polymers slip while being extruded, but the phe-
nomena seemed to depend upon the type of surface. I asked
Eric about that, and described some of the surfaces mentioned
briefly in the paper. He proceeded to line them up for me,
explaining which ones would allow slip at the lowest pres-
sure drop, etc. Impressed, I called the author (at an industrial
laboratory); the paper had not been completely forthcoming,
but the author confirmed that the sequence Eric provided was
exactly what was found in the laboratory.

Chemical Engineering Education











ERIC AS CHAIR
Eric was appointed acting chair of chemical engineering in
1999 and soon became the permanent chair. One of the high-
lights of his chairmanship has been the preparation and ex-
ecution of the department's Centennial, a celebration of the
beginning of the department in 1904. It involved hundreds of
people to organize, and Eric seems to have tapped into his
student experience as an actor and techie to pull off the pag-
eantry to the last detail. With Eric in the driver's seat, the
event was carefully crafted to show off the department to
alumni, the university, and ourselves. He reports he had the
usual "opening night" jitters, but all the planning made for a
memorable event. In the end, even his planning for contin-
gencies got tested, as a thunderstorm erupted just as we were
about to leave the luncheon to walk to the laboratories.
Eric enjoys hearing stories from retired alumni and values
their friendships. In turn, alumni have been very generous to
the department, and Eric loves the stories they tell about
chemical engineering in the "early days." Chuck Matthaei
(of Roman Meal Bread) has shown great interest in educa-
tion and recently endowed a professorship. Neil Duffie (of
Willamette Industries) knows what is important and chal-
lenges Eric to think strategically; Neil has been a longtime
supporter of graduate fellowships.

PERSONAL CHARACTERISTICS
I have always valued Eric's creative side. If there is an idea
to explore "outside the box," Eric is one of the people I want
in the group. In addition to his comprehensive knowledge,
his willingness to forge his own path means he has a knack
of looking at problems in different, sometimes quirky, ways,
and this spawns new ideas.
Eric is not all fuel cells and surface reactions, though. Well-
known for his love of Gary Larson's Far Side cartoons, he
has an endearing sense of humor that can defuse tense situa-
tions. His love of music is also well known: He and his wife
Monika attend the opening night of Seattle Opera every year.
Eric even drew upon his theatrical side at the departmental


TABLE 1
Stuve's Ph.D. Graduates

Naushad Kizhakevariam Varian in Portland
Rod Borup Los Alamos National Laboratories
David Sauer Intel
Thomas Jarvi UTC Fuel Cells
Timothy Pinkerton Intel
Dawn Scovell Intel
Suresh Sriramulu Tiax Consulting (formerly Arthur D. Little)
Seng-Woon (David) Lim UW Chemistry Dept.
Thomas H. Madden United Technologies Research Center
Chris Rothfuss U.S. Department of State
Nallakkan Arvindan Symyx Corp.

Spring 2006


holiday party in December 2005, when he serenaded the at-
tendees by singing "O Tannenbaum."
Further evidence of his well-developed nonscientific side
is his practiced penmanship: Eric's mother was artistic, and
Eric learned calligraphy-so well, in fact, that his wife re-
quires a card done in the elegant writing style for birthdays
and special events. The artistic streak carries over to Monika,
as well, who has achieved "teacher" status in Ikebana flower
arranging. She quickly learned the Japanese art and has even
displayed her accomplishments at a Seattle show along with
a Japanese master and his entourage.
The Stuves also enjoy traveling, and one benefit of Eric's
fuel cell research has been an increase in opportunities to do
so. A repeat destination is Bangkok, Thailand, as part of an
exchange program Eric participates in with Dow Chemical
and the Chemical Technology Department of Chulalongkom
University. During their last visit, they encountered a situa-
tion we all hope to avoid. As the plane took off from Bangkok,
a bird flew into an engine and the pilot aborted the takeoff. In
the process, a wheel caught fire, and the plane was evacuated
at the end of the runway. While the plane was quickly empty-
ing, Eric was concerned about his wife and son Kurt, who
were also onboard. As if sliding down the chute weren't
enough excitement, it took some time for the family to re-
unite. Then, more problems appeared. Since everyone had
left their carry-on baggage on the plane, no one had their
passport. Thus, they could not enter Thailand again while
waiting for another plane the next day! Eventually, sanity
occurred among the authorities, and the passengers were taken
to a nearby hotel to spend the night. The next day the plane
took off without incident, and Eric and his family returned to
Seattle safe and sound, and none the worse for wear. Leave it
to Eric to take such an unplanned "pit stop" in stride.

CONCLUSION
With his commitment to keeping students on the right track
and his fundamental approach to problems, you might say Eric
is the kind of chemical engineering educator who helps set the
pace for our profession. Not bad for an Indy fan. 1


TABLE 2
Equipment in Stuve's Laboratory
Differential Electrochemical Mass Spectrometer
Ultra-high vacuum (UHV) analysis chamber (4)
Potential step chronoamerometry
Linear and nonlinear electrochemical impedance spectroscopy (EIS and NLEIS)
Field Ionization/Emission Microscopy (FIM/FEM)
X-ray photoelectron spectroscopy (XPS or ESCA)
Low energy electron diffraction (LEED)
Thermal desorption spectroscopy (TDS)
Time-of-flight mass spectrometer (TOF-MS)
Auger electron spectroscopy (AES)
Contact potential difference (CPD)
Electron stimulated desorption ion angular distribution (ESDIAD)










] department


Some exhausted members of the Tulane University Uptown recovery team on Sept. 15, 2005-two weeks after
Hurricane Katrina. Left to right: Greg Potter (chemistry, Washington Univ.), James Peel (Bruker Instruments), Russell
Schmehl (chemistry), David Mullin (cell and molecular biology), Scott Grayson (chemistry), Qi Zhao (chemistry),
Gary McPherson (chemistry), W Godbey (CBE), Brian Mitchell (CBE), Vijay John (CBE), and Bob Garry (microbiology).



From Survival to Renewal


Katrina and its Aftermath

at Tulane's Chemical and Biomolecular Engineering Department



BRIAN S. MITCHELL, JOHN A. PRINDLE, HENRY S. ASHBAUGH, AND VIJAY T. JOHN
Tulane University New Orleans, LA 70118


he Chemical and Biomolecular Engineering Depart-
ment at Tulane University has a rich tradition dating
back to 1894, as the first established program in chemi-
cal engineering in the South and the third program in the coun-
try.'" Tulane University faced a struggle for survival in the
fall of 2005 when the city of New Orleans was devastated in
the wake of the flooding from Hurricane Katrina. This article
chronicles the experiences of the department and its efforts
not just to maintain viability but also to look to the future
with a renewed sense of purpose. In keeping with the


university's approach to describing the events of the period
between Aug. 29, 2005, and the present, the article is divided
into three sections: survival, recovery, and renewal.
As background, we give the reader an idea of the depart-
ment. At the time of Katrina, there were nine full-time fac-
ulty (Professors O'Connor, Papadopoulos, Law, Mitchell,
Ashbaugh, Godbey, Lu, De Kee, and John), two staff mem-
bers (Dr. Prindle who serves as a senior instructor and labo-
ratory supervisor, and Ms. Lacoste, the departmental admin-
istrative secretary), and Professor Emeritus Gonzalez, who


Copyright ChE Division of ASEE 2006
Chemical Engineering Education










participates in teaching graduate courses and in collabora-
tive research. The department had about 30 graduate students
studying toward their Ph.D., and about five part-time M.S.
students. Undergraduate enrollment was about 80 with gradu-
ating classes between 15 and 20 students. Undergraduate in-
terest in the program, and enrollment numbers along with it,
saw a steady increase as a result of the recent emphasis and
inclusion of biomolecular engineering into the curricu-
lum in 2003.

SURVIVAL
Residents in the New Orleans area are accustomed to threats
from hurricanes, but there had been none to hit the city since
Betsy in 1965. The horrendous traffic jams and inconve-
niences of evacuation that were experienced when Hurricanes
Georges and Ivan came close but missed the city convinced
many that evacuation was unnecessary. A
sense of complacency had set in. But
Katrina was no mere threat. By Aug. 25, it It was pc
was clear the storm was zeroing in on the heartwa
New Orleans area. Some 300 miles off
shore, the hurricane strengthened to a Cat- the g
egory 5 status, giving sufficient reason for students
the university to initiate evacuation plans helping u
for students. Ironically enough, the week- labor
end of Aug. 27 was supposed to be the resume
faculty's annual welcoming of the latest activity
batch of freshmen, but hasty departures though
were being urged instead. President Scott damage
Cowen called a meeting of all students and mnts,
ments, th
requested that they all return home or
evacuate to Jackson on buses the univer- up and
sity had arranged. Temporary housing had livable
also been arranged for evacuating students opened t
at Jackson State University. Our faculty and hem
made individual plans for the storm while wit
making sure their graduate students had
concrete evacuation plans. Two of our fac-
ulty decided not to evacuate prior to Katrina, but the conse-
quent flooding and the infrastructure and security issues in
the city mandated they leave a few days after the hurricane.
Most faculty and students first evacuated toward the Baton
Rouge, Houston, and Jackson areas.
The events of Hurricane Katrina have been well docu-
mented. We all watched the disaster in real time with acute
sadness, for we could clearly identify with all the locations
in the images. The stress was heightened by the fact that
phones were not working and we were unable to get in touch
with our colleagues and students. Tulane's information tech-
nology services were disrupted and university e-mail ad-
dresses were useless. Communication was slowly established
through text-messaging and the use of temporary e-mail ad-
dresses. It was at this time that Hank Ashbaugh got through


to colleagues in the chemical engineering community with
his request for help in placing our students (see box on page
82 for his personal recollections). Vijay John followed up
with a separate e-mail. The department will forever be grate-
ful for the outpouring of help for our students and faculty.
The major ChE departments geographically closest to
Tulane-in Houston and in Baton Rouge (Rice, the Univer-
sity of Houston, and LSU) took in many of our students and
offered our faculty laboratory and office space-we are so
tremendously thankful.
Katrina wrought significant damage to Tulane. Two-thirds
of our picturesque campus in the historic Uptown neighbor-
hood of New Orleans had flooded. Winds from Katrina dam-
aged the roofs of several buildings. The computer systems
were down, with the university backup tapes located safely
yet inaccessibly in high-rise buildings downtown near the
Superdome, the site of so much trauma and
sadness. The upper administration was op-
cularly rating from Tulane's Executive Business
S School campus in Houston-the saga of
g to see how they brought back function to opera-
late tions and coordinated the recovery is an
ck and interesting story in itself (see
ean the ). The breakdown in
ies to payroll systems was the first major crisis,
earch since the university had no idea how to is-
Even sue paychecks or even a way to identify
le had those on its payroll. We were dealing with
part- emergency financial personnel who had to
teamed be educated that a graduate stipend simply
meant salary. With the help of the deans,
-e with department chairs, and faculty members, all
Itments employees and graduate students were
r doors identified and paychecks issued through
o those direct deposit. Professor Dan De Kee, who
it. also serves as the associate dean for gradu-
ate studies, was invaluable as he kept the
pressure on payroll administration from his
evacuation location of Gaithersburg, Md. In many instances,
the university simply took the word of the deans that indi-
viduals belonged on the payroll and issued paychecks. It is to
the credit of the university that all employees and graduate
students were paid during the entirety of the period be-
tween Sept. 1 and Dec. 31, 2005, while the university re-
mained closed.
Within a couple of weeks following Katrina, faculty mem-
bers Brian Mitchell and Vijay John-who live to the north
and to the west of the city-had returned to their homes, grate-
ful to find minimal damage. John Prindle, who lives near
Baton Rouge and had not evacuated, served as a communi-
cations conduit (see his personal account in box on page 83).
Hank Ashbaugh slowly traveled from Jacksonville, Fla., up
the eastern seaboard to Troy, N.Y. (Rensselaer) where he even-


Spring 2006


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Professor Hank Ashbaugh's recollections of
connecting with his research group and
the chemical engineering community

After Hurricane Katrina hit on Aug. 29, 2005, a sense
of helplessness grew in me as I watched the perpetual
coverage of the flooding of New Orleans from my father's
house in Jacksonville, Fla. The storm had knocked out
the phone network for anyone with a New Orleans area
code, so communications with the faculty in my depart-
ment were spotty at best. Foremost on my mind was where
my research group had scattered in the wake of Katrina.
I quickly located one postdoc who still had a New York
area code on his cell phone, and learned that he'd safely
evacuated with Professor Yunfeng Lu's group to Shreve-
port, La. More worrisome were the two graduate students
from India who had just arrived in the United States to
join my group the week before the storm. How do you
locate two newcomers to this country who had scattered
in a panic? Then I remembered that I had recruited these
two students from UICT with the help of Professor VG.
Pangarkar. I e-mailed him at 11 p.m. and by 2 a.m. my
two students had contacted me to say they were safely on
their way to Texas.
My success in locating my far-flung group gave me the
idea that we should try to reconstitute the department over
the Internet. The first step was to locate the individual
faculty members. The Internet servers for Tulane had been
shut down before the storm, so using campus e-mail ad-
dresses was out. Instead, on Sept. 1, I wrote an open e-
mail to the chemical engineering community-copying
every department chair-to tell our story and request the
whereabouts of any Tulane faculty. The response was
phenomenal. Over the course of the next three days I re-
sponded to over 400 e-mails wishing us well, volunteer-
ing support, and, more importantly, giving me clues as to
where our faculty had evacuated. Within a week and a
half I managed to locate all our faculty, get alternate con-
tact information for each, and begin to reassemble the
department. Two weeks after the storm I sent a second e-
mail to the ChE community providing news ofourfaculty's
whereabouts. As faculty members were being located, we
started to compile lists of graduate and undergraduate
students to expand our "virtual" department. Using the
contacts we had developed outside the department, we
were able to connect students with departments and uni-
versities that had volunteered to host them during our
semester in exile. To facilitate interdepartmental commu-
nications, we created a blog ( TulaneCBE/>) to disseminate information on support for
students, student registration, communications from our
chair, and miscellaneous tidbits. Moreover, the blog pro-
vided a window for our friends outside the department to
keep updated on our status. I


tually spent the rest of the semester. During his travels, he
stopped in at universities along the way (North Carolina, Dela-
ware, Princeton) where he had studied. Kyriakos
Papadopoulos also evacuated to New York (Columbia) after
a two-week stay in Lafayette, La. W Godbey ended up in
Houston (Rice) by way of Huntington, W.Va., Dallas, Texas,
Grapevine, Texas, and Fort Smith, Ark. Kim O'Connor went
to Houston (Baylor Medical School); Yunfeng Lu to Albu-
querque (University of New Mexico) by way of Houston;
Richard Gonzalez to Jackson, Miss.; and Ms. Lacoste to rela-
tives who live north of the city. Victor Law went to Angleton,
Texas, and had to evacuate a second time due to Hurricane
Rita. Our students were scattered all over the country and
were welcomed in at all universities. We had survived the
hurricane. The next step was to plan our recovery.

RECOVERY
The early days following the hurricane, when the campus
and surrounding Uptown neighborhood were without elec-
trical power, are detailed in Brian Mitchell's account of the
recovery efforts (see box on page 85). The university hired
Belfor, an international disaster-recovery corporation, and the
campus was teeming with Belfor employees. Huge power
generators and trailers were scattered across campus as Belfor
set about draining water from building basements (note: base-
ments in New Orleans = bad idea!), gutting damaged floors,
and reinstalling utilities. By early to mid-October, electrical
power had been restored to the neighborhood and most of the
campus had power, with the notable exception of the science
building where electrical transformers and other utilities
placed in the basement had been destroyed. The university's
senior administration had returned to the city and had started
operations in the main administration building (Gibson Hall).
From there they monitored the recovery and began the strat-
egy for renewal.
From the department's perspective, this was a time to take
stock of our losses. Brian Mitchell, Vijay John, and John
Prindle were among a handful of faculty and staff cleared for
regular entry into the engineering building. All other employ-
ees had to get clearance to enter the building (usually by call-
ing Brian or Nick Altiero, the dean) and were escorted into
the engineering building by Brian to recover computer hard
drives, etc. There were significant safety issues, as the build-
ing ventilation systems had not yet been decontaminated.
During the months of October and November, the computer
and communication systems at Tulane returned to normal
operation and we slowly transitioned back to our university
e-mail addresses. It was an interesting time, as Brian, John,
and Vijay came in almost every day to man the phones, keep-
ing in touch with our colleagues and our students. We had to
balance these duties with our personal lives, in which Katrina
had impacted school openings for our children, job condi-
tions for our spouses, and much more. There was very little


Chemical Engineering Education










time for intellectual work. It was a time in which we all real-
ized the frailty of the human condition and learned to act
with newfound compassion. Three of our colleagues had suf-
fered such damage to their homes that they needed tempo-
rary housing. Overall at Tulane, 25-40 percent of the employ-
ees had homes significantly damaged by flooding. There was,
and continues to be, a resounding spirit of helping one another.
We learned several lessons from our experiences in sur-
vival and recovery that are useful to pass on. When planning
for disasters, science and engineering departments should al-
ways take into account the consequences of electrical power
and communication failures
for extended periods. It is wise
to maintain extra supplies of
liquid nitrogen to preserve bio-
logical samples. Personnel and
graduate students should have
alternative e-mails that can be
accessed anywhere through
the Internet. Inventories of
chemicals, instruments, and
general property must be
maintained by the department.
Access to buildings under re-
pair should be tightly con-
trolled even to employees-a
faculty member paying a nos-
talgic visit to the medical
school building before the
power had been restored is
said to have caused significant
water damage by using the
plumbing while the system
was under repair. Even if
thawed biologicals (e.g., tissue
samples) have been removed,
decontamination of the entire W Godbey contempt
building must be performed his dewarfull of


under professional supervision.
By early December, most buildings were functional and
the campus was being spruced up for the return of the stu-
dents. Faculty members throughout the university were ex-
cited about returning to work. President Cowen and the up-
per administration had done a wonderful job in maintaining
student morale by presenting Tulane as a unique institution
where rigorous education would be combined with excep-
tional opportunities to participate in public service to rebuild
a great city. Early registration rates were high and the faculty
was looking forward to the future. We knew that the univer-


lates the whoosh of liquid nitrogen vapors that indicated
biological samples was still cold-evidence that years
of research were still safe.


Dr. John Prindle's recollections of maintaining connections with the undergraduates
Students are any chemical engineering department's lifeblood. They challenge ihe faculty to continually improve teaching
skills. Their tuition pays for a portion of the department's expenses. And with each freshmen class comes a distinctive
view of the world and how to improve it. In many ways, students are a department's primary legacy. So, it is not surprising
that a strong personal connection forms between faculty members and each student they instruct.
In the aftermath of Hurricane Katrina, this personal connection was severely tested. For more than a month after the
event, the university's network servers were down, rendering the familiar student e-mail addresses useless. Shortly after
Tulane announced it was canceling the fall semester, students began calling faculty at home to discuss their options.
Student concerns ranged from whether they should attend another university for the semester to whether they should
register for chemical engineering coursework at that university. During these discussions, the faculty realized most
students simply wanted to be reassured that we would assist them any way we could. With each call, students were
See Maintaining Connections with Undergraduates,
continued on page 98

Spring 2006 8





































Members of the faculty and instructional staff in less stressful times. From left, standing: W T. Godbey,
Daniel De Kee, Vijay John, Yunfeng Lu, Kim O'Connor, Kyriakos Papadopoulos, Brian Mitchell,
and John Prindle. Seated: Richard Gonzalez, Hank Ashbaugh, Victor Law.


sity, as with all employers in the New Orleans region, would
be in a difficult financial situation. But there was a conta-
gious spirit to get the students back, work hard, build up re-
search, and try to recover. It was particularly heartwarming
to see the graduate students back and helping us clean the
laboratories to resume research activities. Even though some
had damaged apartments, they teamed up and those with liv-
able apartments opened their doors and hearts to those with-
out. Yunfeng Lu, who lives a block from campus, feverishly
worked to repair his damaged home so his sizable group of
graduate students could have a place to stay if they were un-
able to find appropriate accommodations.

RENEWAL
On Dec. 8, the Board of Administrators at Tulane Univer-
sity announced a renewal plan as a consequence of the finan-
cial exigency. The plan has turned out to be the largest re-
structuring of an American institution of higher education on
record. Under the plan, some 230 faculty members were ter-
minated, including 35 members of the School of Engineer-
ing. The Departments of Civil and Environmental Engineer-
ing, Mechanical Engineering, Electrical Engineering, and
Computer Science have been slated for elimination by the
fall of 2007. The university has been reorganized with the
formation of a School of Liberal Arts and a School of Sci-
ence and Engineering, in addition to the professional schools,
to fully constitute a comprehensive university. Chemical and


Biomolecular Engineering is one of only two surviving engi-
neering departments; Biomedical Engineering is the other.
Both were merged into the School of Science and Engineer-
ing, which has been further divided into academic divisions.
Biomedical Engineering is now part of the Division of Bio-
logical Sciences and Engineering. Chemical and Biomolecu-
lar Engineering and the Department of Chemistry form the
Division of Chemical Science and Engineering. The entire
renewal plan makes for fascinating reading for those inter-
ested in academic organization, strategy, and administration.
It can be found at . Long-term
goals of the plan as stated by the Board of Administrators
are: (1) diligence in retaining our institutional quality and
working to heighten that quality; (2) dedication to providing
an unparalleled, holistic undergraduate experience for our
students; (3) continued strengthening of core research areas
and graduate programs that build on our strengths and can
achieve world-class excellence; and (4) an absolute commit-
ment to using the lessons learned from Katrina to help re-
build the city of New Orleans and to then extend those les-
sons to other communities.
We mourn the breakup of the School of Engineering, an
institution that existed for over a century. We also mourn the
departure of our colleagues who have worked tirelessly to
improve the school. It is sufficient to say that we will con-
tinue to work hard toward enhancing the reputation of the
department. The current dean of the engineering school, Nick
Chemical Engineering Education










Altiero, has been appointed the new dean of the School of
Science and Engineering. We believe his appointment indi-
cates the university's recognition that engineering is still a
significant and continuing component of Tulane, and we look
forward to working with him to renew, reconstitute, and ex-
pand engineering as opportunities present themselves. He has
been clearly told that the Board of Administrators will be
receptive to new ideas for engineering at Tulane upon return
to financial stability.
What is the future of the department? The university is ex-
pected to return to financial stability within a couple of years,
with the bond market expressing confidence in the strong
management team at Tulane.2'1 Our student body has returned
and we are back to high intensity in both research and educa-
tion. Our informal merger with chemistry is a seamless fit.
Over the years, the two departments have formed strong
bonds, with research collaborations and an environment of
mutual support. The atmosphere of cooperation has led to
the establishment of superb instrumentation facilities in ad-
vanced spectroscopy, electron microscopy, and organic and
inorganic analysis. We are especially proud of our high-reso-
lution electron microscopy and confocal microscopy facili-
ties wherein we are instituting a full range of cryoimaging
techniques for biological imaging. Collaborations with the
Medical School have been set up and we are considered a
vital player in Tulane's objective to become world-class in
health sciences research. Such collaborations are in stem-cell
culture, gene delivery to cancer cells, and vaccine develop-
ment and delivery technologies. The department has signifi-
cant strengths in the areas of computational chemistry, self-
assembly, nanostructured materials, colloid science, and poly-
mer and ceramics processing. The university has clearly stated
its intent to bring every Ph.D.-granting department up to na-
tional prominence, and we expect significant investments to
our department as the university returns to financial viability.
The next couple of years will be difficult. In addition to
their intellectual lives, faculty and students will worry about


rebuilding their personal lives, which must come first. Kind-
ness and compassion will be the order of the day in the de-
partment in dealing with such issues. It will also be terribly
exciting to witness and participate in the rebuilding of the
city. It is incredibly heartening to see students mobilizing on
all kinds of public service projects, from involvement in public
school education, to gutting destroyed houses so that resi-
dents can return to rebuild and establish communities, to pro-
viding meals to the thousands of laborers who are working to
rebuild the city.
We are determined to persevere. Please wish us well ..
and come visit.

ACKNOWLEDGMENTS
W T. Godbey made very helpful suggestions to the article.
The faculty, staff, and students of the Department of Chemi-
cal and Biomolecular Engineering express our deepest grati-
tude to our colleagues in the chemical engineering commu-
nity for their many gestures of kindness in the wake of Hur-
ricane Katrina, and for their numerous forms of support in
helping us to re-attain our prestorm level of excellence.
Department chair's note: I am privileged to work with my
faculty and staff colleagues who showed so much courage
and dedication to restoring the department to viability. The
three coauthors of this article (Prindle, Ashbaugh, and
Mitchell) were especially helpful with their efforts to contact
every undergraduate and graduate student and their efforts to
restore the research infrastructure. They were always avail-
able to help, and Professor Mitchell coordinated the entire re-
covery aspects of the engineering school. To rebuild the depart-
ment with such colleagues is the best job I could hope for.

REFERENCES
1. Westwater, J.W., "The Beginnings of Chemical Engineering in the
USA," Adv. Chem. Setr, 190 141 (1980)
2. Chronicle of Higher Education, Jan. 27 (2006)
3. Walz, J.Y., Chem. Eng. Ed., 246, Fall (1995) 0


Professor Brian Mitchell's narrative on the recovery of our physical facilities
Two weeks after Hurricane Katrina, the department's personnel situation was still critical, but much more stable. All
faculty and staff had been located and were in communication, most undergraduates had been advised which courses to
take at their host institutions, and graduate students were in contact with their advisors. While many continued to struggle
with personal issues related to assessment of their home damage, FEMA, the Red Cross, insurance, accommodations,
and informingfriends and family of their whereabouts, it became clear that it was time to give some attention to the status
of departmental facilities, especially those related to research. The concern for research facilities was uniform through-
out Tulane's research community, but the urgency in engineering was associated primarily with biological samples that had
now been in unreplenished liquid nitrogen (LN)-cooled dewars for two weeks in the sweltering New Orleans summer heat.
Laura Levy, senior vice president for research, authorized a convoy for Sept. 15 to the Tulane campuses to assess
damage. The convoy, led by John Clements, professor and chair of microbiology and immunology, departed early that
Thursday morningfrom the Tulane University Regional Primate Center in Covington, which is located on the Northshore
See Recovery of Physical Facilities
continued on page 86

Spring 2006 8.











Recovery of Physical Facilities
Continued from page 85


of Lake Pontchartrain and had not received any significant
damage from the storm. The eight-vehicle convoy consisted
of researchers from both Uptown (Engineering and Science)
and Downtown (Medical School) campuses, and traversed
the 24-mile Lake Pontchartrain Causeway bridge in record-
setting time with the assistance of a police escort. Its entrance
into the city marked for many of the recovery-team members
their first views of Metairie and New Orleans since the hur-
ricane. The sights, sounds, and smells did not bode well for
finding facilities intact.


Upon arriving at the Uptown campus, the
Downtown team continued on to the more
heavily damaged Medical School campus,
while the representatives from Science and
Engineering set to work. The team from the
Chemical and Biomolecular Engineering
Department consisted of Professor and
Chair Vijay T. John, Assistant Professor W
T. Godbey, and Professor Brian S. Mitchell.
Flashlights in hand, the team entered the
Lindy Claiborne Boggs Center for Energy
and Biotechnology around 9 a.m., and
trudged up the back stairs to the third and
fourth floors that comprise the bulk of the
department's research facilities.
An initial scan of the department showed
it to be in relatively good condition: no


blown-out windows, no water damage, and no indications of
unauthorized entry, save for one broken interior window in
the department's Electronic Classroom. A keypad on the door
and no missing equipment in the classroom soon led to the
conclusion that security personnel had broken the glass sim-
ply to gain entry and evaluate damage. As doors were opened
and each lab inspected, hope grew that the department had
evaded major damage. Lab benches looked as if students had
simply left for lunch. Only one lab had minor damage, the
result of a window being left partially open and the hurri-
cane-force winds toppling some glassware.
The team then concentrated its efforts on two general ar-
eas: securing biological samples and recovering research
data. W Godbey was elated to find that his LN, dewar full of
biological samples-including rare cells and tissue specimens
that were collected over years of research--was still cold.
(One can equate his joy at seeing the cold, white cloud rise
from his liquid nitrogen storage freezer with the emotions
exhibited by JPL engineers when a probe successfully lands
on Mars.) He quickly replenished the dewar with LN, from a
pre-Katrina storage tank in his lab, and did the same with


Professor Kim O'Connor's samples in an adjacent labora-
tory. The team then collected biological samples from dew-
ars in the Biomedical Engineering Department, consolidated
the samples into one 25 1 dewar with wheels, and placed the
dewar by a service elevator to facilitate future refilling op-
erations. Some thought was given to carrying the portable
dear down the stairs and placing it on the first floor since
there was no power in the building, but there were indica-
tions that power to the elevators could be restored on a tem-
porary basis, if necessary. Unfortunately, biological samples
that had been frozen in a refrigerator freezer were no longer
cold and had begun to decompose. DNA samples that had
been placed in a freezer to slow decomposition could with-
stand room temperatures for moderate time periods, so they
were still salvageable and were therefore re-
trieved.


Similar operations related to the collection
and consolidation of biological samples were
conducted in the chemistry and biochemistry
departments, as well as at the Downtown cam-
pus. For example, a recent Public Broadcast-
ing NOVA segment documents the heroic efforts
of Tulane researcher Tyler Curiel to save irre-
placeable sinonasal undifferentiated carcinoma
(SNUC) samples from his laboratory ( www.pbs.org/wgbh/nova/sciencenow/3302/
08.html>). LN, is also critical to the operation
of some advanced analytical tools, such as
Nuclear Magnetic Resonance Spectrometers
(NMRs). Gary McPherson and Russell
Schmehl, our colleagues from chemistry, dili-
gently worked to ensure that the NMR magnets


in both the Department of Chemistry and Tulane's Coordi-
nated Instrumentation Facility (CIF) did not quench. Even-
tually, these units also required that their liquid helium res-
ervoirs be recharged, a task which involved several other
dedicated individuals from both chemistry and CIF.
The recovery of research data consisted primarily of re-
trieving laboratory notebooks and computers fiom investi-
gators' offices and labs. It was unknown at that point how
long the university would remain closed, and some investi-
gators had not decided whether to relocate to other universi-
ties for the semester. Many opted to leave their computers for
the time being. As it turned out, Tulane would be closed for
the entire semester, and many faculty members did indeed
relocate to continue their research, if only out of their homes.
As a result, many computers and hard drives were retrieved
during subsequent recovery trips. The retrieval and shipping
of computers for faculty, staff, and graduate students proved
to be problematic. Some requested only hard drives, which
required opening computers, and some requested not only
computers, but monitors and other peripherals as well. Ship-
ment of large pieces of equipment required travel to neigh-


Chemical Engineering Education


As doors were
opened and each
lab inspected, hope
grew that the
department had
evaded major
damage. Lab
benches looked as
if students had
simply left for
lunch.









































boring communities where postal facilities were open (and
packed with people trying to get their mail). In some cases,
computers and supplies were driven to their final destina-
tions by faculty or staff members. Much of this effort could
have been avoided with proper data storage practices. Though
there are certainly security and accessibility issues with off-
site data storage, in a case like this, in which faculty is forced
to scatter to various locations without sufficient warning to
retrieve or back up data, the ability to retrieve important in-
formation from a neutral site would be invaluable. One such
resource currently under development is the Louisiana Opti-
cal Network Initiative (LONI)- LONI2005/)>-which will provide a high-speed optical net-
work for researchers at a number of Louisiana universities,
including Tulane. But until such networks are in place and
easily accessible to the research community, individual in-
vestigators must accept the responsibility for ensuring that
their research data are secure and readily retrievable. A list
of other "Lessons Learned" is shown in Table 1. An area for
further research is listed in Table 2.
By Sept. 26, residents were being allowed back into Or-
leans Parish on a limited basis, so police escorts and con-
voys were no longer necessary. Recovery trips to the campus
continued, and it was during the ensuing six- to eight-week
period that the majority of computers and research equip-
ment were removed to allow investigators to continue their
research at external sites. In most instances, the investiga-
tors, or their representatives, were escorted onto the Uptown
campus by either the dean of engineering or his designee. All


TABLE 2
More Information Needed

There is an issue with vapor phase vs. liquid phase storage of
biologicals: There is a high probability that fungal spores will be
floating in LN,, and if the storage tubes are submerged in the liquid
then there is a chance of sample contamination. On the other hand, a
full dewar. if left unopened, can keep samples cold for months. Some
kind of study would help clarify whether liquid phase storage is
indeed safe for biologicals.

visitors to campus had to be cleared with the Office of Public
Safety prior to their visits, and random identification checks
from armed security officers were the norm. A system was
established for recording institutional identification numbers
for all equipment removed from the campus. Investigators
were allowed to remove equipment for research purposes,
but were informed that doing so could have insurance impli-
cations; i.e., if there was hurricane-related damage, they may
not be able to prove it since insurance adjustors had not yet
arrived on campus. A few investigators moved their labs-
equipment, graduate students, and all-to host universities
for the semester. Some chose to remain at Tulane and carry
out their research with graduate students who had either re-
mained behind or returned. By mid-November, escorted vis-
its had virtually ceased, cleanup operations were well under
way, and the Department of Chemical and Biomolecular
Engineering was gearing up for the spring term. Tulane
University officially opened to faculty and staff on Dec.
19, 2005, and the spring 2006 term began Jan. 16, 2006,
right on schedule. O


Spring 2006


TABLE 1
Some Lessons Learned

For brief power interruptions, a chest freezer is preferable to an upright freezer for storage of biologicals at -80 because it will remain
cold for longer periods of time.
If space and funds permit, store biological samples in LN, rather than a freezer, because
a full LN, dewar will stay cold for months, even in 100 F heat, if unopened: however...
Biological the storage of tissue samples with bacterial samples creates a potential contamination issue, so ...
a a transform bacteria and lyophilize the modified culture broths with bacteria in them, for storage at room temperature for
indefinite periods of time.
Keep an adequate supply of LN, on hand.
Consolidate LN, samples into one container whenever amenable, even if that means sharing one between laboratories, subject to the
constraints described above.

Back up your electronic data on a regular basis to an easily retrievable location.
Research Consider replacing your desktop computer with a laptop and docking station so data is easily portable in an emergency.
Data Have students store research notes, laboratory notebooks, and samples in a predefined location so critical nonelectronic data can be
easily located in their absence.
Store flammable research notebooks in a fireproof and waterproof container.

Place all electrical devices on appropriately sized battery backups with surge protection to guard against short-term power interruptions.
Electrical
Equipment For longer power interruptions, if time permits, shut down all electrical devices and turn off electrical breakers to prevent damage due
to power surges upon being re-energized.











re curriculum


DESIGN PROJECTS OF THE FUTURE






JOSEPH A. SHAEIWITZ AND RICHARD TURTON
West Virginia University Morgantown, WV 26506-6102


It is generally accepted that the chemical engineering pro-
fession is in a state of change. Fewer graduates from U.S.
chemical engineering departments are entering the pe-
troleum, petrochemical, and chemical industries, since most
expansion in these industries is not in the United States. More
graduates from U.S. chemical engineering departments are
entering product-based industries (e.g., pharmaceutical, food,
new materials) rather than the traditional commodity-chemi-
cal-based industries (ethylene oxide, benzene, sulfuric
acid)."' 2 Therefore, changes in the undergraduate chemical
engineering curriculum-which has been static for about 40
years (not counting advances in computing)-are imminent,
if not already in progress.
Three significant changes in the chemical engineering cur-
riculum are under way.13' First of all, biology is now consid-
ered to be an "enabling" science, along with chemistry and
physics. Some education in the life sciences will soon be re-
quired for accreditation.[4] Secondly, chemical engineers need
to be taught about product design, either instead of or in ad-
dition to process design. It will become more important to
teach batch operations, since the manufacture of new chemi-
cal products will certainly involve batch rather than continu-
ous operations. Finally, over the past generation, advances in
chemical engineering research have involved the ability to
understand and to manipulate phenomena at the colloidal,
nano, molecular, and atomic scales. A key issue is the effect
on macroscopic properties of colloidal-, nano-, molecular-,
and atomic-scale phenomena, i.e., structure-property relations.
It is time these advances became part of the undergraduate
curriculum.
Radical changes to the traditional chemical engineering
curriculum have been proposed.'' Changes are on the hori-
zon, although the speed and degree of implementation of these
changes is not yet obvious. It could also be argued, however,
that traditional chemical process engineering must still be
taught, because the soon-to-retire baby boom generation must
88


be replaced by newcomers equally capable of operating, main-
taining, and updating existing chemical plants.
Given the importance of the capstone experience in the
undergraduate education process, a question that arises when
considering curriculum changes is: What will the capstone
chemical engineering design project of the future look like?
It is virtually certain that the capstone chemical engineering
project of the future will not involve sulfuric acid or ethylene
oxide production. Instead, it may have a life science basis. It
may involve design of a product. It may involve multiscale
phenomena, i.e., the effect of nano- or molecular-scale inter-
actions on the performance of the product. It is more likely to
involve batch processing than continuous processing. And, it
is also possible that manufacture of items and unit packag-
ing-two concepts far removed from traditional chemical
engineering-will be included.


Joseph A. Shaeiwitz received his B.S. de-
gree from the University of Delaware and his
M.S. and Ph.D. degrees from Carnegie
Mellon University His professional interests
are in design, design education, and out-
comes assessment. Joe is an associate edi-
tor of Journal of Engineering Education, and
he is a co-author of the text Analysis, Syn-
thesis, and Design of Chemical Processes
(2nd Ed.), publishedby Prentice Hall in 2003.


Richard Turton received his B.S. degree
from the University of Nottingham and his
M.S. and Ph.D. degrees from Oregon State
University. His research interests are in flu-
idization and particle technology and their
application to particle coating for pharma-
ceutical applications. Dick is a co-author of
the text Analysis, Synthesis, and Design of
Chemical Processes (2nd Ed.), publishedby
Prentice Hall in 2003.

Copyright ChE Division of ASEE 2006
Chemical Engineering Education











In an effort to initiate a new capstone-design paradigm, the
yearlong capstone design project at West Virginia University
for 2003-04 and 2004-05 involved biologically oriented,
multiscale product designs. These two projects are described
in this paper. More details are available elsewhere'"5 and from
the authors.

CLASS ORGANIZATION
In the senior year of chemical engineering at West Virginia
University, the entire class works on a large project for two
semesters under the direction of a student chief engineer. More
details are presented elsewhere.161 Briefly, faculty members
play roles: one is the client, for whom the students are "hired"
to complete a design project; another is the "vice president"
of the students' company, who helps the students with tech-
nical matters. The student chief engineer divides the class
into groups, each headed by a group leader. The role of the
chief engineer is to represent the entire team to the client and
to provide leadership from the "big picture" perspective. The
group leaders receive assignments from the chief engineer
and are responsible for completing the work within their
groups. Assignments are deliberately vague and open ended.
One goal is to force students to define their own work state-
ment, with input from faculty members. Another is to learn
material not normally taught in class. The exact topics stu-
dents must learn are a function of the project. A further goal


is to make students realize that they will have to continue
learning new material throughout their careers, and that they
have the ability to do so.
In the fall semester, the project involves researching alter-
natives and a feasibility study. For example, in ice cream pro-
duction, the assignment was to identify, screen, and recom-
mend food products for production, with attention focused
on products that have low-fat and/or low-carbohydrate alter-
natives. Students set their own direction with a minimum of
input from the instructors. The client chooses one alternative
for design in the spring semester. This is really the only op-
portunity for the instructors to influence the direction of the
project; however, the client's choice is always one of the top
two student recommendations.


ICE CREAM PRODUCTION
This project was completed by 26 students over the course
of the entire 2004-05 academic year. It started with a very
open-ended assignment: to investigate opportunities in food
processing, particularly those involving low-fat and low-car-
bohydrate alternatives. The market for these foods was to be
analyzed, and the issues associated with producing the low-
fat and low-carbohydrate alternatives were to be identified.
A summary of the colloidal- and molecular-scale issues iden-
tified by students is shown Table 1. Production of any of these


TABLE 1
Examples of Colloidal- and Molecular-Scale Processing Challenges in Food Manufacturing

Product Processing Challenge

Ice Cream Ice crystal formation must be kept to a minimum. Otherwise, the ice cream has a grainy texture.
Nut and fruit size must be controlled to control the rheology. Processing conditions must be controlled to prevent nuts and fruit
additives from becoming soggy.

One method for making low-fat ice cream have the same mouth feel as regular ice cream is slow churning, a proprietary process of
Edy/Dreyers.'1 By churning the ice cream at higher pressures and lower temperatures, smaller, more dispersed fat globules are
formed that have similar mouth feel to regular ice cream.

Cookies Almond flour is often substituted for wheat flour in low-carbohydrate cookies. Since almond flour contains more fat, the result is a
chewier cookie.

Granulated sugar is required in cookie manufacture so that the sugar will spread throughout the cookie during baking. Coarse sugar
results in cracking. This has implications as to which sugar substitute can be used in low-carbohydrate cookies.

Reduced-fat cookies require longer baking times to allow the existing fat to coat the flour and sugar particles.

For sandwich cookies to stick together, the surface energy of the solid must be higher than that of the filling. One way to accom-
plish this is to raise the temperature of the filling and add more fat to the filling, both of which reduce its surface energy. (This is
also true for ice cream sandwiches.)

Bread Protein and fiber are often substituted for wheat flour in low-carbohydrate bread. Binding agents are required to hold these
ingredients together. Dough conditioners are added for strength.

Cereal Bars Binders are added to hold the cereal pieces together. They crosslink to form a flow-resistant structure. There are two common
binders. One involves dipolar interactions between OH groups on glucose molecules in the binder and the cereal pieces. The other
involves COO- groups bonding covalently with the cereal pieces.

Spring 2006 89










products would make a good design project. Each involves
batch processing of a product as well as manipulation at the
molecular or colloidal levels to obtain desired macroscopic
properties. Another feature involved, but traditionally unfa-
miliar to chemical engineers, is packaging.
Students used product screening methods to rank the alter-
natives.[71 Ultimately, ice cream production to capture 1% of
the domestic market was chosen for a complete design. Pro-
duction of 1.75-quart containers plus some novelties (pops
and bars, in this case) were included in the design. Ice cream
production involves traditional chemical engineering, prod-
uct design, and multiscale analysis. It involves application of
principles of chemical engineering at scales from the mo-
lecular level to the process level.
Ice Cream Science. There are three categories of ingredi-
ents in the ice cream mix: dairy, sweeteners, and additives.
Milk, cream, and nonfat milk solids make up the dairy por-
tion of ice cream. Sucrose or Splenda is used to sweeten the
mix, and stabilizers and emulsifiers are added to give the ice
cream the desired body and mouth feel. Significant quanti-
ties of air are also present in finished ice cream. Standard ice
cream contains an equal volume of mix and air, or an "over-
run" of 100%. Premium ice cream, however, has an overrun
of only 80% to give it a richer, more-creamy,
mouth feel.


Stabilizers and emulsifiers are essential in the production
of ice cream products. Both components help to give ice cream
a smooth body and texture and help to improve the overall
mouth feel of the ice cream. Stabilizers work by reducing the
amount of free water in the ice cream mixture. This retards
ice-crystal growth during storage and also provides resistance
to melting. Stabilization is accomplished through two mecha-
nisms, depending on the type of stabilizer used, and both
mechanisms may be involved depending on the structure of
the gum used. Charged gums, such as carageenan, help to
reduce the amount of free water because the charged groups
interact with water to restrict the movement of water mol-
ecules within the mixture. Branched gums, such as guar gum,
also reduce free water within the system. This is accomplished
because the branched side chains contain hydroxyl groups
that hydrogen-bond with water, a reaction that also reduces
the amount of free water. Similarly, emulsifiers help to re-
duce fat-globule coalescence by stabilizing the fat globules
within the ice cream matrix. Mono- and diglycerides are the
most commonly used emulsifying agents. The addition of sta-
bilizers and emulsifiers is particularly important for ice
cream base mixes that are lower in fat content, because
whole milk already contains natural stabilizing and emul-
sifying materials.


Milk is a colloidal suspension of water,
fat, and milk solids. Fat particles in the sus-
pension range in size from 0.8 to 20 pm. The
sugar-lactose-is also present in milk, at a
concentration of about 4.9%. In "lactose-
free" ice creams, the milk is treated with
the enzyme lactase, which breaks lactose
down into the simpler sugars glucose and
galactose.
In this design, regular table sugar, or su-
crose, is used as a sweetener in all the ice
cream mixes except the low-carbohydrate ice
cream. Sucralose is used to sweeten the low-
carbohydrate ice cream because it is indigest-
ible but still sweetens the mix.


0

0
S,
> 5 -

A I
^,


0 5 10 15 20 25
Shear Rate (1/sec)


*Atkins Low-Carb
* Kroger Standard
A Haagen-Dazs@ Premium


30 35 40


Figure 1. Viscosity of different ice cream products.


Mixing Pasteurization & AgngFlavor
-' Ingredients Homogenization Aging Mixing





-- Freezing Cartoning Hardening



Chemical Engineering Education


Figure 2.
Block flow diagram
for ice cream
production.










The viscosity of ice cream varies with the type. During a
class tour of a local ice cream production facility, the host
remarked that production of low-carbohydrate ice cream was
"difficult on the equipment," which had been placed into
operation before low-carbohydrate ice cream was developed.
Further investigation revealed that many ice creams, particu-
larly the low-carbohydrate vanillas, contain TiO, pigments
to make the ice cream look whiter. It is possible that the TiO,
colloidal particles cause erosion of process equipment. Stu-
dents also wondered whether there was a variation between
viscosities of different ice cream types. One student, who was
doing research in the polymer research laboratory of our col-
league Rakesh Gupta, measured the viscosity of three types of
ice cream. The results are shown in Figure 1. Low-carbohy-
drate ice cream is clearly more viscous than standard ice cream.
Facility Design. A facility to manufacture, store, and ship
ice cream was designed. Production volumes were 52 mil-
lion 1.75-quart ice cream containers (varying flavors), 2.3
million six-packs of sandwiches, and 4.3 million six-packs
of pops (ice cream bars with sticks). The manufacturing pro-
cess of the ice cream facility is broken down into seven steps,
as illustrated in Figure 2. A 5400-m2 warehouse for ice cream
storage was also designed. It was designed to hold three
months of production. Because of the need to refrigerate the
warehouse, the construction requires special insulation, and
the capital investment for this part of the process (>80%)
dominates the overall fixed capital investment (almost $100
million)-a result that was not anticipated.


Refrigeration Cycle. Refrigeration (600 tons) is required
three places: in the warehouse, in the hardening step in ice
cream production, and for cooling the milk at the front end of
the process. An ammonia refrigeration-cycle design, used for
the warehouse, is displayed in Figure 3. The refrigeration cycle
is a traditional chemical engineering component of this de-
sign. Using the number of interstate coolers on the compres-
sors and the type of cooling medium used in E-101 through
E-104 as decision variables, students optimized the refrig-
eration process.

Steam Generation. In the facility, low-pressure steam is
used for pasteurization, for jacketed heating of the mixing
equipment, and for heating water for equipment cleaning.
These steps are necessary to ensure that there is no product
contamination by bacteria, which is part of "good manufac-
turing processes" in food production. Therefore, a typical
steam-production facility was designed.

Wastewater. A system was designed to process wastewater
from the ice cream manufacturing facility. There were two
reasons for this. First, it was assumed that the ice cream plant
would produce too much additional wastewater for an exist-
ing municipal wastewater facility. Second, based on infor-
mation from the local water authority, having a water treat-
ment facility in-house appeared to be the less-expensive op-
tion. Wastewater treatment is needed because the equipment
must be cleaned daily, generating significant amounts of
wastewater. The operation plan involves production on two







C-103


Figure 3.
CW C-104 PFD for the
optimized
16 ammonia
refrigeration
cw E-102 system
Wf n\n, unit 1.


Spring 2006













Figure 4.
Block flow diagram
for transdermal
drug delivery patch
manufacture.


shifts per day followed by a cleaning shift. Most
of the cleaning is done using hot water.
Economics. It costs approximately $0.56 to
produce a 1.75-quart container of ice cream, in-
cluding the initial capital investment. Even with
the markup associated with the food distribu-
tion chain, the process is very profitable. The
net present value (NPV) was found to be $97
million, assuming a 10-year plant lifetime and
a 15% before-tax rate of return. A Monte Carlo
analysis showed that there is only an 8% chance
of losing money, i.e., an NPV less than zero.
Remarks from an ice cream expert at the final
student presentation indicated that prices for
milk products could vary over a wide range,
leading to significantly greater variation in the
NPV. These factors were not considered in
the students' analysis but could easily be in-
corporated.

DESIGN OF A TRANSDERMAL
DRUG DELIVERY SYSTEM


Patch Stratum
Corneum


This project was completed by 11 students
over the course of the entire 2003-04 academic
year. It also started with a very open-ended as-
signment: to investigate alternative forms of
drug delivery, and to suggest a product to be
manufactured. Within the transdermal patch
category, students learned the properties that
make a drug suitable for use in a transdermal
Pa
patch, which are: (1) low molecular weight, (2)
high potency, so low dosage required, (3) resis-
tance to enzymes in skin layers, and (4) desire
to have constant dosage in body over time. Item
number 4 means that a transdermal patch would
not be used to treat a simple headache, because,
for a headache, rapid entry of the drug into the
blood is desired. Students used product-
screening methods to choose between alternative drugs."'
Ultimately, production of a contraceptive transdermal
patch for females was chosen for a complete design.


Epidermis


K,

C1


C2



Patch Stratum
Corneum


Dermis Capillary Blood
Wall


C2.





c2,=o C3=0

Blood


Figure 5. Model for diffusion through skin layers.


Figure 6. Two-compartment pharmacokinetic model.

Patch Design. The patch contains norelgestromin and ethinyl
estradiol. The proposed size of the patch is 10 cm2, manufac-
tured as a single-layer, matrix system.


Chemical Engineering Education


Weighing
- & Coating Drying Laminatio-
Mixing



Cutting
SInspection ----- & Cartoning
1 Packaging


Co


M, M,










Pressure-sensitive adhesives are the common form of ad-
hesive used in transdermal systems. They are permanently
tacky at room temperature, they are easily applied with light
pressure, and they do not require solvents for activation.
Polyisobutylene was chosen because it provides excellent
adhesion in high-moisture environments and because of its low
cost. Polyisobutylene has a surface tension of 30-32 dyne/cm,
which is lower than the critical surface tension of skin of 38-
56 dyne/cm, depending on humidity and temperature. There-
fore, the adhesive will wet the skin-a requirement for adhe-
sion. This is an example of colloid-scale considerations in
the transdermal patch design.
Skin penetration enhancers increase the mass flux of a drug
across the desired surface area. The driving force for the drug
is the concentration gradient between the patch and the skin.
The enhancer used in this patch is crospovidone, which draws
water to the surface of the skin. This in turn causes swelling,
which provides more surface area for diffusion.
Excipients are ingredients within a drug product that are
considered inactive, from a pharmacological perspective. In
this case, there is one excipient used, propylene glycol
monolaurate, which acts as an emollient.
Manufacturing. The block flow diagram for manufacture
of the transdermal patch is shown in Figure 4. It is a batch
operation. First, the ingredients must be weighed and mixed.
The drugs are mixed with the adhesive. The appropriate mix-
ing time and impeller arrangement are estimated using typi-
cal chemical engineering principles.'8' Then, the mixture is
coated on the backing. Hexane is used as a solvent to help
lower the viscosity of the solution and to ensure a well-mixed
product. After coating, the hexane is evaporated and is sub-
sequently incinerated, because it was determined that there
was not enough hexane present to justify a recovery system.
Next, the release liner is added to sandwich the drug/adhe-
sive mixture. After inspection (as required by law) large sheets
are cut into 10 cm2 patches, packaged individually, and then
packaged again, three per carton. Finally, cartons of the three-
packs are packaged for distribution.
Part of the design involved identifying "good manufactur-
ing practices" in the pharmaceutical industry, which ensure
that the product is pure and free of contamination.
Economics. Students determined that the cost of manufac-
turing one patch is between $0.28 and $0.30, depending on
employee salaries and the plant location. The U.S. pharmacy
price for a similar, brand-name product is approximately $15
per patch. Since this product is to be a generic version, it was
assumed that its price would be about half of the brand-name
product. The markup at the pharmacy is assumed to be twice
the price for which it was purchased. Therefore, the estimated
manufacturer's patch price is $3.75. Selling the patches for
$3.75 per patch yields a net present value of $684 million
assuming a 10-year plant lifetime and a 15% before-tax rate


A ... goal is to make students realize that
they will have to continue learning new
material throughout their careers, and that
they have the ability to do so.


of return. No information was available from industry sources
to verify these assumptions or the resulting NPV estimate.
Mathematical Modeling. In the design of a transdermal
patch, the dose is a key factor to consider. The drug is deliv-
ered from the patch to the body by diffusion through the
multiple layers of skin, so students were required to model
diffusion through multiple, immiscible layers. The flux of a
given drug from a transdermal system into the body can be
modeled as shown in Figure 5a. The result is

Cn
Co n
j C MJ (1)
1 x-,n 1


K


n( n
Ku M
Sj-1 )


where CO is the concentration of the drug in the patch, K is
the inverse of the resistance to diffusion of the drug provided
by each skin layer, and M. is the partition coefficient of the
drug between a layer and the subsequent layer (M = Cj/C.).
It was found that the rate-limiting step is diffusion through
the stratum corneum layer. So, if it is assumed that the con-
centration in the blood is zero (Cn = 0), the model reduces to
Figure 5b, and Equation (1) becomes
j=CoKiM1 (2)
A pharmacokinetic model was also developed, which can
be used to predict the concentration of the active ingredients
in the blood. The model is illustrated in Figure 6, and the
equations are

dC1 -k1C1
dt V,

dC2 kC, -k2C2
dt V2
where C, is the concentration of an active ingredient in the
patch, k, is the elimination rate constant from the patch, V, is
the volume of the patch, C, is the concentration of the active
ingredient in the blood, k, is the elimination rate constant
from the blood, and V, represents the volume of blood in
which the drug is distributed. Students fit this model to pub-
lished data to determine the values of k, and k.[9, 10]
Multiscale Design. In terms of multiscale analysis, design
of a transdermal drug delivery system requires design from
the molecular scale through the macroscopic scale. These


Spring 2006










items are summarized in Table 2. At the molecular scale, the
drug itself is designed. This is beyond the scope of this project.
At either the molecular or nano scales, one finds the pres-
ence of excipients and/or enhancers in the patch. The adhe-


sive to hold the transdermal patch
to the skin could involve design
at multiple scales. Since the drug
is mixed with the adhesive, if there
were a molecular interaction be-
tween the drug and adhesive, it
would have to be understood. For
an adhesive to stick, it must wet
the skin, so an understanding of
colloid-scale wetting phenomena
is required. The patch must be re-
moved without significant dis-
comfort, yet not become detached
in the shower or during physical


DISCUSSION
One of the advantages of a project such as ice cream pro-
duction is that it has traditional chemical engineering com-
ponents (e.g., refrigeration cycle, wastewater treatment, steam


TABLE 2
Length Scales and their Application to
the Transdermal Patch Problem

nano scale the action of enhancers and excipients at
a molecular level on the skin surface
colloid scale mechanism of adhesion
transdermal transport phenomena
micro scale
pharmacokinetics
macro scale product manufacture


activity that causes sweating-both macro-scale phenomena.
At the microscopic scale, the mechanism of transport of the
drug through the skin must be understood. Modeling drug
transport through the skin layers is standard transport phe-
nomena. Similarly, there is system modeling, in which the
pharmacokinetics of the drug in the body can be modeled.
Finally, at the macroscopic scale, the components must
be combined appropriately, manufactured into the desired
product, and packaged for sale.

ASSESSMENT
Two assessment measures were used. In one, the two in-
structors use a rubric to evaluate, separately, all aspects of
the final design report and oral presentation submitted by the
students each semester. This rubric was developed in the con-
text of more traditional chemical engineering design prob-
lems. For example, since biology is not (yet) required in our
curriculum, it is not listed as a science that students are ex-
pected to demonstrate an ability to apply. The ability to learn
and to apply biological concepts as needed is evaluated un-
der the ability to learn new material not taught in class. The
complete rubric is available on the Web."" Table 3 shows the
results, averaged for the two instructors, for both projects.
The score of three indicates meets expectations, and the score
of four indicates exceeds expectations. Clearly, our assess-
ment of the students suggests that they exhibited superior
performance in the ability to teach themselves new material.
In our student evaluation of instruction, it is possible for
the instructor to add an individually defined question. Table
4 shows several such questions and the student responses.
The responses are on a 5-point Likert Scale, thus indicating
student responses were all between "agree" and "strongly
agree." Therefore, we conclude that the students involved in
these projects believed them to be beneficial.


the design. For example,


production) along with multiscale
considerations, product design and
manufacture, and packaging. De-
sign of a transdermal drug patch has
a stronger life science component
and involves more transport phe-
nomena-oriented mathematical
modeling (i.e., systems analysis)
than a traditional chemical pro-
cess design.
While the multiscale aspects of
these projects have been identified,
the molecular-scale phenomena
have not yet been incorporated into
we do not believe that we are in a


position to design a new drug or to manipulate the micro-
structure of ice cream. If, however, a product design assign-
ment were based on a faculty member's research, it might be
possible to include molecular-, nano-, or colloidal-scale de-
sign aspects, especially if students were in a position to per-
form experiments.
A reasonable question is what other design projects of this
type are envisioned. The list of potential life science-related
projects is long and could include innovative drug-delivery
devices (e.g., drugs on a chip) or tissue growth. Our class of
2003 designed a facility for the batch production of amino
acids.i'' Design of a microprocessor production facility would
involve multiscale phenomena and could also involve tradi-
tional chemical engineering in the production of ultra-pure
water and in wastewater treatment. Design of an advanced
material based on its micro- or nano-structure is also pos-
sible. The importance of multiscale phenomena in paper
manufacture was recently presented,'121 so manufacture of fine
paper products is a possibility.
More detailed synopses of these projects are available on
our design project Web site.'51 The final reports are also avail-
able to faculty members by contacting the authors.

CONCLUSIONS
As the profession of chemical engineering moves toward
product development and design and away from process de-
velopment and design, a new paradigm for chemical engi-
neering education is evolving, requiring a new generation of
capstone design projects. Two examples have been presented
here. In ice cream manufacture, multiscale considerations are
important, yet there are traditional chemical engineering com-
ponents included. Production of other food products involves


Chemical Engineering Education











many of the same considerations. In design of a transdermal
drug delivery patch, life science considerations, multiscale
factors, and systems modeling are required. Both involve as-
pects of product design. They also require manufacture and
packaging of unit items-topics traditionally foreign to chemi-
cal engineering education. As the chemical engineering cur-
riculum changes in response to the changes in our profes-
sion, similar design projects will find their way into capstone
experiences.

ACKNOWLEDGMENTS

The following students worked on the transdermal patch:
Matthew Anderson, Jeffrey Bickar, Gregory Hackett, Joseph
Kitzmiller, Lindsay Kruska, John Ramsey, Samuel Smith,
Craig Travis, Ugochi Umelo, Jennie Wheeler, and Clayton
Williams.
The following students worked on ice cream production:
Jess Arcure, Jon Baldwin, Benjamin Banks, Adam Byrd,
Timothy Daniel, Mariana Esquibel, Kyle Gallo, Lina Galvis,
Joseph Jones, Matthew Kayatin, Dennis Lebec, Daniel
Malone, Jonathan Miller, Joshua Mounts, David Newcomer,
Rebecca Orr, Coleen Pell, Michael Pfund, James Rhoades,
Joshua Rhodes, Rebecca Seibert, James Sims, Michael Velez,
William White, Jason Williams, and Joanne Winter.


Portions of this paper were presented at the 2004 ASEE
Annual Meeting, Salt Lake City, UT, session 3413
transdermall patch) and at the 2005 ASEE Annual Meeting,
Portland, OR, session 3113 (ice cream).

REFERENCES
1. Cussler. E.L.. and J. Wei. "Chemical Product Engineering." AIChE J.
49, 1072-1075 (2003)
2. Cussler. E.L., "Do Changes in the Chemical Industry Imply Changes
in Curriculum?" Chem. Eng. Ed.. 33(1) 12 (1999)
3.
4. Criteria forAccrediting Engineering Programs (2006-07 cycle), ABET,
Inc., Baltimore, p. 27
5.
6. Shaeiwitz, J.A., W.B. Whiting, and D. Velegol, "A Large-Group Se-
nior Design Experience: Teaching Responsibility and Lifelong Learn-
ing." Chem. Eng. Ed., 30(1), 70 (1996)
7. Turton. R., R.C. Bailie, W.B. Whiting, and J.A. Shaeiwitz, Analysis,
Synthesis, and Design of Chemical Processes, 2nd Ed., Chapter 24.
Prentice Hall PTR, Upper Saddle River, NJ (2003)
8. Oldshue, J., Fluid Mixing Technology, Chapter 15, McGraw Hill, New
York (1983)
9. Kydonieus, A.F, and B. Bemer, Transdermal Delivery of Drugs, Vol-
ume II. CRC Press, Boca Raton, FL (1987)
10. OrthoEvra Full Prescribing Information, Ortho-McNeil Pharmaceu-
ticals. Raritan, NJ (May 2003)
11.
12. Hubbe. M.A.. and O.J. Rojas, "The Paradox of Papermaking," Chem.
Eng. Ed.. 39(2). 146 (2005) 7


TABLE 3
Assessment Results for Design Projects

Assessment Patch Ice Cream

Design of equipment, understand interrelationship between equipment in process 3.0 3.0
Apply chemistry, math, physics. engineering science 3.5 3.5
Resolve complex problem into components 3.0 3.5
Apply economic, physical constraints, and optimization methods to obtain solution 3.0 3.0
Use of computer-based and other information systems 3.0 3.0
Demonstrate ability to learn new material not taught in class 4.0 4.0
Demonstrate ability to function in assigned role 3.0 3.0
Demonstration of ethical behavior 3.0 3.0
Demonstrate understanding of societal impact and need for assigned design 3.0 3.0


TABLE 4
Student Evaluation of Instruction Results

Result Group Out of
Asked 5.0

Tackling the nontraditional problem posed in the large-group project enhanced my confidence in solving new problems. Patch 4.90
I feel that my experience with the group design taught me the importance of and the need for continuously learning new material. Patch 4.17
In my career, I will be required to solve problems appearing to be outside the mainstream of chemical engineering, Ice cream 4.17
such as food processing.
I feel confident that I can apply my chemical engineering knowledge to any application. Ice cream 4.40
The teamwork experience in this class will be valuable in my future career. Ice cream 4.57


Spring 2006











Random Thoughts...




A WHOLE NEW MIND

FOR A FLAT WORLD



RICHARD M. FIELDER
North Carolina State University


Interviewer: "Good morning, Mr. Allen. I'm Angela
Macher-project engineering and human services at Con-
solidated Industries. "
Senior: "Good morning, Ms. Macher-nice to meet you."
I: "So, I understand you're getting ready to graduate in
May and you're looking for a position with Consolidated...
and I also see you've got a 3.75 GPA coming into this semes-
ter-vely impressive. What kind of position did you have in
mind?"
S: "Well, I liked most of my engineering courses but espe-
cially the ones with lots of mnali and computer applications-
I've gotten pretty good at Excel and Matlab and I also know
some Visual Basic. I was thinking about control systems or
design.
I: "I see. To be honest, we have very few openings in those
areas-we've moved most of our manufacturing and design
work to China and Romania and most of our programming
to India. Got any foreign languages?"
S: "Um, a couple of years of Spanish in high school but I
couldn't take any more in college-no room in the curricu-
lum."
I: "How would you feel about taking an intensive language
course for a few months and moving to one of our overseas
facilities? If you do well you could be on a fast track to man-
agement."
S: "Uh...I was really hoping I could stay in the States. Aren't


Richard M. Felder is Hoechst Celanese Pro-
fessor Emeritus of Chemical Engineering at
North Carolina State University. He received his
B.ChE. from City College of CUNYandhis Ph.D.
from Princeton. He is coauthor of the text El-
ementary Principles of Chemical Processes
(Wiley, 2005) and codirector of the ASEE Na-
tional Effective Teaching Institute.



Copyright ChE Division of ASEE 2006


any positions left over here?"
I: "Sure, but not like 10 years ago, and you need different
skills to get them. Let me ask you a couple of questions to see
if we can find a fit. First, what do you think your strengths
are outside of math and computers?"
S: "Well, I've always been good in physics."
I: "How about social sciences and humanities?"
S: "I did all right in those courses-mostly A's-but I can't
honestly say I enjoy that stuff."
I: "Right. And would you describe yourself as a people
person?"
S: "Um...I get along with most people, but I guess I'm kind
of introverted."
I: "I see . ." (Stands up.) OK, Mr. Allen-thanks. I'll
forward your application to our central headquarters, and if
we find any slots that might work we'll be in touch. Have a
nice day."


This hypothetical interview is not all that hypothetical. The
American job market is changing, and to get and keep jobs
future graduates will need skills beyond those that used to be
sufficient. This message is brought home by two recent
books-Thomas Friedman's The World is Flat' and Daniel
Pink's A Whole New Mind--that I believe should be required
reading for every engineering professor and administrator.
The books come from different perspectives-the first eco-
nomic, the second cognitive-but make almost identical
points about current global trends that have profound impli-
cations for education.
An implication for engineering education is that we're
teaching the wrong stuff. Since the 1960s, we have concen-
trated almost exclusively on equipping students with analyti-


TA. Friedman, The World is Flat, New York, Farrar, Straus, & Giroair,
2005.
SD.H. Pink, A Whole New Mind, New York, Riverhead Books, 2005.


Chemical Engineering Education










cal (left-brain) problem-solving skills. Both Friedman and
Pink argue convincingly that most jobs calling for those skills
can now be done better and/or cheaper by either computers
or skilled foreign workers-and if they can be, they will be.3
They also predict that American workers with certain differ-
ent (right-brain) skills will continue to find jobs in the new
economy:
El creative researchers, developers, and entrepreneurs
who can help their companies stay ahead of the
technology development curve;
El designers capable of creating products that are
attractive as well as functional;
El holistic, multidisciplinary thinkers who can recognize
complex patterns and opportunities in the global
economy and formulate strategies to capitalize on
them;
El people with strong interpersonal skills that equip them
to establish and maintain good relationships with
current and potential customers and commercial
partners;
E people with the language skills and cultural awareness
needed to build bridges between companies and
workers in developing nations (where many manufac-
turing facilities and jobs are migrating) and developed
nations (where many customers and consumers will
continue to be located);
E self-directed learners, who can keep acquiring the new
knowledge and skills they need to stay abreast of
rapidly changing technological and economic
conditions.

Those are the attributes our students will need to be em-
ployable in the coming American engineering job market.
The question is, are we helping them to develop those at-
tributes? With isolated exceptions, the answer is no. We still
spend most of our time and effort teaching them to "Derive
an equation relating A to B" and "Calculate Z from specified
values of X and Y." We also offer them one or two lab courses
that call on them to apply well-defined procedures to well-
designed experiments, and we give them a capstone design
course that may require a little creativity but mostly calls for
the same calculations that occupy the rest of the curriculum.
Nowhere in most engineering curricula do we provide sys-
tematic training in the abilities that most graduates will need
to get jobs-the skills to think innovatively and holistically
and entrepreneurially, design for aesthetics as well as func-
tion, communicate persuasively, bridge cultural gaps, and
periodically re-engineer themselves to adjust to changing
market conditions.


Why don't we? It's because people as a rule don't want to
leave their comfort zones, and engineering professors are as
subject to that rule as anyone else. We are all comfortable
deriving and solving equations for well-structured single-dis-
cipline systems, but most of us are not so sure about our abil-
ity to handle ill-defined open-ended multidisciplinary prob-
lems or to teach creative thinking or entrepreneurship. So,
despite a crescendo of headlines and best-sellers about the
growing exodus of traditional skilled jobs to developing coun-
tries (including high-level research and development jobs,
which are increasingly moving to India and China4), many
engineering faculty members vigorously resist suggestions
to make room in the curriculum for multidisciplinary courses
and projects or anything that might be labeled "soft." Even
though most of our alumni in industry-95%? 99%?-as-
sure us (as they have done for decades) that they haven't seen
a derivative or integral since they graduated, the traditional-
ists still insist that we can only produce competent engineers
by devoting almost every course in the curriculum to deriv-
ing and solving equations, analytically and with Matlab. The
same professors are no less resistant to efforts to move them
away from the traditional "I talk, you listen" pedagogy toward
the active, cooperative, problem-based approaches that have
been repeatedly shown to equip students with the skills Fried-
man and Pink are talking about. (See bibliography on p. 113.)
So far we've gotten away with it, although sharply declin-
ing engineering enrollments in recent years should be a red
flag. We can't count on getting away with it much longer,
however. The relentless movement of industry to computer-
based design and operation and offshoring of skilled func-
tions and entire manufacturing operations is not about to go
away. On the contrary, as computer chips get faster and de-
veloping countries acquire greater expertise and better infra-
structure, the movement will inevitably accelerate. The Ameri-
can engineering schools that respond by shifting toward more
multidisciplinary problem- and project-based instruction-
the way Olin, Rowan, Rose-Hulman, the Colorado School of
Mines, and a number of others have already started to do-
will survive. The schools that try to stick with business as
usual may not. I

Ifyou don't think this is already happening in engineering, check out
a 2005 NAE Report called "Offshoring and the Future of U.S. Engi-
neering: An Overview," weblinkslMKEZ-6G6R4D?OpenDocument>.
e S. Lohr; "Outsourcing is Climbing Skills Ladder," New York Times,
Feb. 16, 2006. This article reports that of200 multinational corpo-
rations surveyed, 38% said they planned to "change substantially"
the worldwide distribution of their R&D work in the next three years
.. and this particular trend is still in its infancy.


Spring 2006


All of the Random Thoughts columns are now available on the World Wide Web at
http://www.ncsu.edu/effective_teaching and at http://che.ufl.edu/~cee/













Maintaining Connections with Undergraduates

Continued from page 83


requested to provide contact information for classmates
(e-mail addresses, cell phone numbers, etc.). If they were
uncomfortable doing this, they were asked to contact
classmates themselves and encourage them to contact
one of the faculty. This approach, along with posting a
request on the department's blog (see Professor
Ashbaugh's account), still only allowed direct contact
information to be gathered for about 50 percent of our
students. The junior and senior classes, however, had
set up their own Yahoo groups prior to the storm, which
meant departmental e-mails ultimately reached more
students. In one instance, a student posted faculty mes-
sages to a Web site the student had built specifically for
sharing department information with classmates. In ret-
rospect, gathering alternate contact information prior
to Katrina as a regular part of getting acquainted with
students would have allowed department outreach ef-
forts to be more effective after the hurricane.
Studentfeedback from phone conversations led to the
realization that our core course curriculum was aligned
with only a fraction of other chemical engineering pro-
grams. Our unique Practice School program during the
senior year'3' requires that most core courses be offered
a semester earlier than other programs. As a result, stu-
dents found it challenging to find the chemical engi-
neering courses they needed. Ofparticular concern were
the seniors and their need to complete a capstone de-
sign course before graduation. Within a day of recog-
nizing this issue, the consensus from the faculty was that
our process design course would be offered during the
spring semester. This information was quickly commu-
nicated to the seniors. The speed with which decisions
of this type were made and communicated ultimately
affected the options our students had during fall regis-
tration. Since Katrina made landfall the weekend be-
fore the semester started, however, even the best efforts
meant students began attending classes at other uni-
versities two to three weeks late.
Many students evacuated New Orleans without their
textbooks or notes. Because of the broad scope of most
capstone design courses, the most affected group was
those seniors who managed to enroll in this course. As
a result, the faculty member who would have taught this
course within our department during the fall semester
offered to provide supporting information from books
that the students owned but left in New Orleans.


Those students who attended other universities in the
fall were requested to send us the name of the university
and the courses for which they were registered. This pro-
vided a means of double checking what the student
thought was an equivalent core course. If the course was
not adequately equivalent, the student was quickly noti-
fied. Under the difficult circumstances, many students
pragmatically chose to take their remaining non-ChE
courses during the fall.
Near the end of September, the faculty began discuss-
ing the course schedule for the spring and Lagniappe
semesters. From the fall registration information pro-
vided by our students, it became evident that offering
all core courses during these two semesters would be a
requirement in order to keep the students on track. By
mid-October, a course schedule for both semesters had
been established which met this objective.
Registration for the spring semester at Tulane began
in early November Two weeks prior to registration, all
students were sent an e-mail requesting they update their
fall course-enrollment information. In this e-mail, stu-
dents were also informed that they would be able to con-
tact three departmental advisors (Drs. Mitchell, John,
and Prindle) by phone for advising assistance over the
five-day period just prior to the beginning of registra-
tion. This call center setup provided the students with
assistance in addressing their registration questions.
Since the university Internet and e-mail servers were
restored in mid-October, there was no problem contacting
all of our students using their university e-mail addresses.
The response to this request was substantially higher.
Several challenges had to be overcome in manning
the call center. Since the campus was closed and secu-
rity was tight, department offices could not be entered
without special permission. In addition, service to de-
partment phones was not activated until the second day.
Despite obstacles, the call center was ultimately suc-
cessful in providing students with assistance in address-
ing their concerns prior to registration.
All of these efforts in establishing and maintaining
the faculty-student connection were difficult under the
challenging conditions. We believe, however, that they
have forged even stronger ties between both groups. As
a result of these experiences, some students feel more
comfortable discussing problems with faculty. Faculty
interest in our students and their well-being has in-
creased as well. While both groups looked forward to
the start of the spring semester and a return to a sense
of normalcy, that normal state will be distinctly differ-
ent. And, in many ways, better. O


Chemical Engineering Education










INTRODUCTION
TO A SPECIAL SECTION ON THE

Patten Centennial Scientific Workshop:




THE NEXT MILLENNIUM


IN CHEMICAL ENGINEERING




CHRISTINE M. HRENYA
University of Colorado Boulder, CO 80309-0424
H. SCOTT FOGLER
University of Michigan Ann Arbor, MI 48109-2136


Over the past several years, a number of chemical
engineering programs around the country have been
honoring the 100-year anniversaries of their origins. The
2004-05 academic year marked a similar time at the
University of Colorado. In 1904-05, coursework for a
B.S. in chemical engineering included Slide Rule, Sur-
veying, Oil and Fuel Laboratory, and Heat Treatment
of Steel, whereas today's curriculum includes courses
such as Engineering Computing, Environmental Sepa-
rations, Polymer Science, Particle Technology, Tissue
Engineering, and Pharmaceutical Biotechnology. Simi-


lar-if not greater-
changes to the chemical
engineering discipline
are expected during the
next century.
To commemorate the
centennial year, a scien-
tific workshop dedicated
to discussions on the fu-
ture of the discipline was
hosted by the Department
of Chemical and Biologi-
cal Engineering at the
University of Colorado
on Feb. 3 and 4, 2005.
The participants included
Professors Kristi Anseth
(Univ. Colorado), Bob


Armstrong (MIT), Arup Chakraborty (UC Berkeley),
Ed Cussler (Univ. Minnesota), Mike Doherty (UC Santa
Barbara), Richard Felder (NC State), and Jerry Schultz
(UC Riverside)-see Figure 1, next page. The work-
shop consisted of two parts, namely oral presentations
and panel discussions. This feature section is intended to
share these exchanges with the greater ChE community.
In the first portion of the workshop, each of the seven
participants was asked to give an oral presentation on a
topic of his or her choice, with a theme that is both
broad in scope and forward thinking. An ordered list-
ing of the talks is given
4. Hrenya is an associate profes- in Table 1, next page.
ical and biological engineering at Corresponding written
ity of Colorado. She joined the fac-
eceiving her B.S. from The Ohio perspectives were re-
rsity and her Ph.D. from Carnegie quested of each partici-
'ersity. She has given over 50 in- prsptiv
is on her research in particle tech- pant; these perspectives
current emphasis of which is granu- are contained in the ac-
uidization, aerosol dynamics, and companying group of
iputational methods.
articles. The manu-
.D. from scripts cover pedagogi-
the Uni- cal issues (Professors
ntly the Armstrong and Felder),
guished
0e is au- a view on the current
reaction chemical industry (Pro-
rests are
kinetics, fessor Cussler), and
pharma- outlooks on emerging
aduated areas (Professors
areas.rty and S
Doherty and Schultz).


D Copyright ChE Division of ASEE 2006


Spring 2006 9


Christine f
sor of chen
the Universi
ulty after re
State Unive
Mellon Univ
vited lecture
nology, the
lar flows, fli
related conf

H. Scott Fogler. After receiving his Ph
the University of Colorado, he joined
versity of Michigan where he is curre
Ame and Catherine Vennema Distin
Professor of Chemical Engineering. H
thor of the text Elements of Chemical F
Engineering. His current research inter
in the areas of colloids, wax gellation
dissolution kinetics of zeolites, and the
cokinetics of acute toxicology. He has gr
36 Ph.D. students in these and related


Copyright ChE Division oj ASEE 2006











The Next Millennium in ChE


Figure 1.
Participants in the
Patten Centennial
Scientific Workshop-
University of Colo-
rado, February 2005.
Top row:
Arup Chakraborty,
Jerry Schultz,
Kristi Anseth.
Bottom Row:
Bob Armstrong,
Richard Felder,
Mike Doherty,
Ed Cussler.
Q AND A
The second portion of the workshop comprised two panel discussions, both of which were driven by questions from
the attending faculty and graduate students. A paraphrased overview of this exchange, grouped according to topic, is
given below. The respondents are indicated according to their initials (see Table 1). Since these discussions took place
after individual presentations, the reader may choose to read this portion after the ensuing manuscripts to keep the
chronology of the interactions intact.
Curriculum
Question (to BA): How do you envision the curriculum change you have proposed occurring (see related
perspective by Bob Armstrong)?
BA: I think we should start with a clean slate and start by adding back in the most important areas and then stop
adding when four years are full. I think the approach should not include adding more classes than we currently
have, as that will lead to an overcrowding of schedules and then the students would have no time to think about
what they are learning.

We have not changed the curriculum in the last 40 years due to the large research engine created after World
War II. Faculty were too busy with research to improve significantly the content in the classroom. Faculty have
to take time from research, for example to write textbooks or Web modules. We need to do this together as a
community of universities. You have got to reward faculty for implementing change.

EC: There is no way that we could possibly do what Bob is saying. Also, committee books are really bad
usually. I think modifications need to be done one course at a time. Let me liken it to the past when periodic
tables were put on the classroom walls. At that time, boiling points were the only important properties we

TABLE 1
Presentation Listing

Participant Title
Prof. Richard Felder (RF) Teaching Engineering in the 21st Century with a 12th-Century Teaching Model: How Bright is That?
Prof. Bob Armstrong (BA) A Vision of the Chemical Engineering Curriculum of the Future
Prof. Arup Chakraborty (AC) Quantitative Cellular and Molecular Immunology: A New Opportunity for Chemical Engineering
Prof. Jerry Schultz (JS) In Vivo Biolmaging: Advances and Challenges
Prof. Ed Cussler (ECY A Different Chemical Industry
Prof. Mike Doherty (MD) Crystal Engineering: From Molecules to Products
Prof. Kristi Anseth (KA) Chemical Engineering in 2020: Return of the J.E.D.I.?


100 Chemical Engineering Education










The Next Millennium in ChE


needed to know because everything was petrochemicals. Now, chemical engineers are using the information on the
periodic table.
Question: With all the changes and additions that have been suggested, do you think there will need to be a five-
year undergraduate degree? Or is it time that we separate the curriculum into new majors (e.g., tissue engineering,
metabolic engineering)?
RF: We cannot put in all the content, since the content is always changing. We have to emphasize how to learn,
skills, flexibility.
BA: You need to learn a good way of thinking-the courses are just vehicles. I think it is a mistake to fractionate
into subareas at the undergraduate level. As a career evolves you are always introduced to new areas, so you learn
to augment knowledge. Incidentally, the renaming of many departments that has occurred recently-to include
"bio" in their name-is very different than the splitting into subareas we are talking about. The inclusion of "bio" in
a department name reflects the change in our underlying molecular core science from chemistry alone to a combi-
nation of chemistry and biology.
EC: If you put in new material, you have to chop out fluff. We can do that by compressing courses (e.g., transport
phenomena). But we also need to adapt to what is relevant. For example, I think it is a tragedy that at Minnesota we
teach thermodynamics without covering the topic of ionic solutions, which has tremendous biological relevance.
KA: It is important to consider which industries we want to serve when implementing changes into our curriculum.
Textbooks
Question: A number of the items discussed thus far have been about modifying courses and teaching new courses.
One problem set I foresee is: Where are the textbooks, when will they come, and how will authors be rewarded?
MD: Scholars are responsible for writing research papers, books, patents, and grants. There is a need to de-
emphasize papers and make a global contribution like writing texts. It's so hard to write a book. Role models are
key-if role models write books then others will be written; if they don't, then there will be no books. A large
problem is that there is insufficient reward for writing texts. Nevertheless, academics should do it as part of their
job.
RF: It is hard to write books-hard and time consuming. Don't write a book before you have tenure. Rewards?
Don't do it for rewards. A book only counts as a publication and the effort it takes is the same as for 25-50 publica-
tions. Write it because you want to write it-it will be a better book if it's a labor of love.
BA: People need to step forward and do it-or at least convince others to do it. One reward is that the reputation of
the school gets better when books are written by faculty. The rewards are not well-translated to individual rewards.
One answer may be to get teams of faculty to write books. The books become much more interesting and have
broader perspective if they are done as truly collaborative efforts, and there's less work per person.
Role of Biology
Question (to JS): What do you see as the future for division of labor between materials science and bioengineering?
JS: We will have some aspects of materials science tailored to bioengineering. Why should a name be changed to
Biochemical Engineering? There was no change to Plastic Chemical Engineering when plastics were the popular
topic in chemical engineering. To be successful, engineering programs must collaborate with true biology pro-
grams. Also, engineers design new products based on physics, chemistry, and biology. Now that we can manipulate
biology, biology is becoming more quantitative.
Question (to AC): Did basic biology prepare you for the biological research you are undertaking?
AC: The curriculum Bob talked about is exactly what is required. Learn the general idea and work from the
molecular up to the macroscopic.


Spring 2006 101











The Next Millennium in ChE


Teaching Methods
Question (to RF): Do you believe distance learning is better? I'm asking about isolationism vs. learning in the
presence of other students?
RF: Compared with an active-learning class, distance learning is not better. There are some things technology can
never replace. I don't believe software will ever be able to motivate students. That's not to say we can't supple-
ment an active-learning classroom with technology.
Question: How should industry perspectives be incorporated into the undergrad classroom?
RF: Take industry problems and bring them into the classroom. Use a problem-solving method and let students
take the lead in making decisions.

JS: Bring in industry representatives to be a part of the design team and problem-solving effort. Use real corpo-
rate resources and financial support to solve real, relevant, industrial problems.
MD: From real-world consulting experience with DuPont, I understand that engineers typically have very short
windows in which to make decisions with limited information. It is important to develop skills to quickly and
hierarchically make these decisions. Each result should yield a "yes" or "no" response for continuing or changing
paths.
EC: Define complex problems and have some process for judging if a commercial product is likely to work.
Expose students to situations where they have to make decisions with limited data.
Enrollments / Future of the Discipline
Question: What is happening with ChE enrollments?
EC: Although we are seeing decreasing enrollments, we should look at the bigger picture. There has been an
increase of 50% in ChE programs and a decrease in enrollment-that makes sense. On my way here, I was doing
a little research and did you know that there are 11 Ph.D. programs in the state of Ohio-that's silly! I think it is
time to start killing programs for undergraduates and graduates.
BA: Undergraduate enrollment is on the increase again. In 2000, there were 6,000 undergraduates enrolling per
year. Enrollment since 1973 can be fit with a sine wave and seems to follow job growth. Times change. It is up to
educators to know what industries are growing/shrinking and make students aware of it. My concern is not so
much at the B.S. level as it is to where are all the Ph.D.s are going to go for jobs?
AC: Ph.D. enrollment is flat during the same time.
JS: In ChE, enrollment varies up to about 10% a year. The amount of high school graduates going into the field of
engineering, however, is about the same. It's all dependent on jobs.
Question: Say I am a high school senior who is really good at math and science. How would you convince me to
be a chemical engineer?
JS: Out of all engineering, chemical engineering has the widest range of basic science. Chemical engineering
offers students a good systems base for the next 30-50 years.
BA: Chemical engineering is preparation for a diverse range of career types.
MD: Our primary asset is that we can provide quantitative solutions. This differentiates us from chemists,
biologists, etc. With a ChE B.S., one can go out into the real world with a good-paying job. Chemists and biolo-
gists tend to have a more difficult time finding more challenging, higher-paying jobs at the B.S. level.
RF: This is the only discipline that can put together so many sciences. Chemical engineers can be found in many,
if not most, technical fields in industry. Also, most students don't know what they are interested in, so it keeps
doors open (e.g., environmental, heath care).


102 Chemical Engineering Education











The Next Millennium in ChE


Global Competition
Question: With the battle for global economy and our standard of living in jeopardy, what are your thoughts on
lower-cost plants and research moving to other countries? How do we innovate and bring new products/technolo-
gies to market quickly to win? What can faculty do?
BA: We need to teach our students marketing, how to identify real needs, and how to solve problems to meet
those needs. We can only succeed if we innovate-not by becoming a service-based country. One minus for the
United States is that our culture is not one that tends to save money. There are concerns that we will not have
money required for investment in R&D.
MD: There is a natural progression in history that the same main group of countries innovates, and the new
technologies/products become more commodity and move to other places, e.g., steel. In the 1880s, the 20 richest
places in the world included North America, Europe, and Australia. In the 1980s the list had not changed much,
with few exceptions, including the addition of Japan to the list. It is fairly hard to screw things up! Well-estab-
lished systems and stable governments lead me to believe things will remain the same.
Energy and Water Research
Question: In the next 50 years, what will be the biggest problem of the world and what role will chemical engi-
neers play in solving it?
EC: Energy and water. I do not think ChEs will dominate health care or food. Regarding water, ultrafiltration to
remove viruses is needed. Regarding energy, gas will cost $6 a gallon in 10 years. Because of that there will be a
renaissance to energy research. A hydrogen economy is controversial and nonsensical. Fuel cells will need a major
breakthrough, and one which is more applied in nature than universities are used to. Thus, universities won't
dominate fuel-cell research.
MD: Energy is a huge problem-a national strategic problem. The developing world, including India and China,
will increase the demand for energy. Two million cars were sold in China last year. In 10 years, there will be more
cars in China than in the United States. India will be much the same as China. Bombay today is wall-to-wall cars.
There will be a massive demand for energy, and not all will come from fossil fuels due to CO, problems. An H,
economy does not change that because H, is also from fossil fuels. The best prospect is nuclear energy. Also,
methane is a big area that needs research funding. Currently, nothing can be done with methane unless it is
compressed to LNG (liquefied natural gas). Right now, 4 billion cubic feet of methane is flared per year. That
amount of energy is equivalent to 300 million barrels of oil. If it were liquefied and consumed by offshore units,
the energy produced would be very useful. Methane can also be changed to other forms for transport but it is not a
priority to the government so success is slow coming. National governments need to make priorities, balancing
CO, generation, global warming, and the risks of nuclear energy. A succession of U.S. governments have had their
heads in the sand, which is a strategic mistake for this country.
BA: Hydrogen is only a carrier-the energy must come from some primary source such as nuclear. There is a
huge need for energy carriers for automobiles. Other areas of energy research include biomass and carbon seques-
tration so that CO, problems can be alleviated. There are, of course, many alternative energy sources including
solar (most expensive now), wind (farms are unpleasing aesthetically, but most economically sound right now),
and biomass (two times the cost of wind). We need a government willing to admit that energy is a problem and
then federal research money will be available. One really good way to get revenue for research is to tax gasoline at
something on the order of 10 to 50 cents per gallon.

ACKNOWLEDGMENTS
We are grateful to the numerous graduate students at the Department of Chemical and Biological Engineering at the
University of Colorado who volunteered their time and helped make this workshop possible. O




Spring 2006 103










SThe Next Millennium in ChE






A Vision of


THE CURRICULUM

OF THE FUTURE




ROBERT C. ARMSTRONG
Massachusetts Institute of Technology Cambridge, MA 02139


Over the past 40 years, the discipline of chemical en-
gineering has undergone dramatic changes. We are
no longer a discipline largely coupled to a single
industry, namely the petrochemical industry. Rather our gradu-
ates go to a wide variety of industries including chemicals,
fuels, electronics, food and consumer products, materials, and
biotechnology and pharmaceuticals.11
Moreover, the character of the chemical industry has
changed significantly, particularly in recent years:
F the chemical industry is today very much a global
enterprise;
F companies have been reshaped by a series of mergers,
acquisitions, and spin-offs;
l some major chemical companies have become life
science companies and spun off their chemical units;
F and the time-to-market for new products has been
significantly shortened.
Similarly, the research enterprise in chemical engineering
has exploded over the past 40 years both in dollar volume
and in breadth. The exciting research opportunities that we
explore today as a discipline were well illustrated in the "Fu-
ture of Chemical Engineering Research" sessions at the 2004
Annual Meeting of AIChE. Particularly notable shifts in re-
search over this period include much more biologically re-
lated research and a much stronger molecular perspective in
the research.
Over this same 40-year period the undergraduate curricu-
lum in chemical engineering has remained nearly unchanged.
The stagnation in the curriculum is well illustrated by Figure
1, which is taken from a paper by Olaf Hougen.121 The flow
chart in the figure shows the evolution of the curriculum de-
cade by decade from 1905 to 1965. In each decade, new con-


tent entering the curriculum is shown as well as material that
was removed in order to "conserve mass." The center of each
box defines a core themes) for the decade.
I would like to make two observations about this figure.
First, over the 60 years shown, the curriculum was very dy-
namic with significant changes in each decade. Second, by
1965 we had developed a curriculum for undergraduate edu-
cation that is very nearly the same as today's. Why is this? It
is possible that after 60 years of hard work on the curriculum
the discipline arrived at a more or less timeless implementa-
tion. But this seems hard to believe in the face of all of the
change that has taken place over the past 40 years outside of
the curriculum. On the other hand, it is possible that we have
simply not paid the attention we should to curriculum devel-
opment over this period. This is what I believe has happened.
This same period has seen an enormous growth in federal
research funding in universities, and this growth is reflected
in the large number of doctoral research programs in chemi-
cal engineering around the country. This research has created
valuable intellectual growth in our community, but it con-
sumes an enormous fraction of the time of our faculty mem-
bers just to keep the research engine running, with grant pro-


Robert C. Armstrong is Chevron Professor and head of the Depart-
ment of Chemical Engineering at the Massachusetts Institute of Tech-
nology. He received a B.ChE. from the Georgia Institute of Technol-
ogy in 1970, and a Ph.D. in chemical engineering from the University
of Wisconsin in 1973. His research interests lie in the areas of poly-
mer molecular theory, polymer fluid mechanics, rheology, multiscale
process modeling, transport phenomena, and applied mathematics.
He is co-author of the two-volume text Dynamics of Polymeric Liq-
uids, which has been named a Citation Classic.


Copyright ChE Division of ASEE 2006


Chemical Engineering Education














The Next Millennium in ChE)


INFLOW

TRANSPORT PHENOMENA
PHYSICAL MEASUREMENTS
DIFFERENTIAL EQUATIONS
COMPUTER PROGRAMMING

APPLIED KINETICS
PROCESS DESIGN
REPORT WRITING
SPEECH
INCREASE IN
PHYSICAL CHEMISTRY
UNIT OPERATIONS
ORGANIC CHEMISTRY
ChE THERMONDYNAMICS
PROCESS MEASUREMENTS
AND CONTROL
INCREASE IN
PHYSICAL CHEMISTRY
UNIT OPERATIONS
GENERAL CHEMISTRY
MATERIAL & ENERGY BALANCES
FUNDAMENTALS


UNIT OPERATIONS


INDUSTRIAL CHEMISTRY
METALLOGRAPHY
APPLIED ELECTROCHEMISTRY
TECHNICAL ANALYSIS
PYROMETRY
SHOPWORK
STEAM AND GAS TECHNOLOGY
CHEMICAL MANUFACTURE


PRINCIPAL
DEVELOPMENTS
ADE VI
TRANSPORT PHENOMENA
PROCESS DYNAMICS
PROCESS ENGINEERING
COMPUTER TECHNOLOGY

DECADE V

APPLIED KINETICS
PROCESS DESIGN
1945
DECADE IV

ChE THERMODYNAMICS
PROCESS CONTROL

DECADE III
MATERIAL AND
ENERGY BALANCES
DECADE II

UNIT OPERATIONS


DECADE I

INDUSTRIAL CHEMISTRY

I 9UO


OUTFLOW

GRAPHICS
[ SHOPWORK
REDUCTION IN
UNITOPERATIONS
MATERIAL AND
ENERGY BALANCES
INDUSTRIAL CHEMISTRY
METALLOGRAPHY
MACHINE DESIGN
STEAM AND GAS
TECHNOLOGY
REDUCTION IN
SSHOPWORK
INDUSTRIAL CHEMISTRY
- MECHANICS
STEAM AND GAS
A TECHNOLOGY
APPLIED
ELECTROCHEMISTRY
CONTRACTS AND
SPECIFICATIONS
--* REDUCTION IN
MECHANICS
MACHINE DESIGN
DESCRIPTIVE
GEOMETRY

HYDRAULICS
SSURVEYING
GAS MANUFACTURE &
DISTRIBUTION
FOREIGN LANGUAGES
REDUCTION IN MECHANICS &
QUANTITATIVE CHEMISTRY


Figure 1.
Changes
in a typical
undergraduate
chemical
engineering
curriculum
during 60 years.
The initial
curriculum
in 1905
consisted of
separate courses
in chemistry and
conventional
engineering.',3


posals, contractors' meetings, review panels, annual
reports, etc. The price has been neglect of the curricu-
lar content in chemical engineering and a widening
gap between the research done in modem chemical
engineering and the content taught in our undergradu-
ate programs.

The opportunities for chemical engineering today Che
are great (see Figure 2). We are uniquely positioned at
the interface between molecular sciences and engi-
neering, and this affords us many opportunities in a
broad range of technologies that lie at the interface
between chemical engineering and other science and
engineering fields. This image of chemical engineer-
ing creates a number of tensions in our curriculum.
There is a strong outward pull on our curriculum to- Fi
ward the many disciplines with which we interact at
the interfaces in Figure 2. The opportunity to teach
our students more about these particular areas of technology
is exciting educationally, but it does tend to have a fragment-
ing effect on the discipline. Opposing the strong outward pull
is an equally compelling need to look inward at the core of
chemical engineering. Some departments have dealt with this
tension by developing curriculum tracks in specialized ar-
eas. Students begin by taking a common core in chemical
engineering and then specialize in a number of technology
areas, e.g., biotechnology, materials. An alternative approach,


Materials
Science


Physics


Structured


Mathematics Computer
Science


Electrical
Engineering
Ironic


ion Mechanical
Engineering


Biology


Civil Engineering


chemistry A~
Cho


'gure 2. Chemical engineering has a special position between
the molecular sciences and engineering.


proposed here, is to refocus on the core content of chemical
engineering. Thinking clearly about what constitutes the core
of chemical engineering that will make our future graduates
key contributors in interdisciplinary problems is essential. It
is important to remember that the current core we teach was
developed when chemical engineering was described by the
horizontal axis in Figure 2. That is, chemical engineering was
dominated by the intersection of chemistry and mechanical
engineering. We need to reexamine whether that core is the


Spring 2006


S





WI











The Next Millennium in ChE


appropriate core for the two-dimensional image in Figure 2.
The broad range of applications of chemical engineering can
be included in the curriculum by way of examples, problems,



It is possible that after 60 years of hard
work on the curriculum the discipline
arrived at a more or less timeless imple-
mentation. But this seems hard to believe
in the face of all of the change that has
taken place over the past 40 years outside
of the curriculum.



case studies, and laboratories. In this way we maintain a com-
mon education for all chemical engineers that demonstrates
the versatility of the degree to all of our students.

CCR/NSF FRONTIERS IN CHEMICAL
ENGINEERING EDUCATION WORKSHOPS
The opportunities for reform in chemical engineering cur-
ricula are so compelling and broad that an appropriate re-
sponse requires wide-ranging participation across the entire
discipline. This is important for a number of reasons. First,
the opportunities/frontiers are too broad for any one depart-
ment or several departments to address effectively. Second,
the costs-time and money-of developing new educational
materials are too high for any of us to absorb alone. Finally,
the coherence resulting from a joint effort will serve the dis-
cipline well in maintaining a clear identity to the world (po-
tential students, industry, and government), ensuring good
manpower supply to industry and to our graduate programs,
and ensuring that curriculum developments are used.
Nearly 100 faculty members from 53 universities along with
industrial representatives from five different companies met
in a series of three workshops sponsored by the Council for
Chemical Research and the National Science Foundation to
discuss curricular opportunities and to map out a path for-
ward. Below I will highlight some of the key findings of the
workshops. I encourage you to look at the detailed work prod-
uct and proceedings from these workshops, which can be
found at .r 3
Before I begin with the summary of the workshop results,
I would like to relate an interesting observation made by many
of us at the workshops: if we think about the curriculum in
the large blocks we usually use-thermodynamics, transport
106


phenomena, kinetics, etc. -then change will be difficult or
impossible. The reason is very simple. The current curricu-
lum is full (or overflowing); if we take these large units to be
givens in a new curriculum, then there is simply no room for
new content. Hence we felt it worthwhile and important to
put everything on the table and to start with a clean slate in
thinking about the future. We asked ourselves, what should a
"Decade XI" box covering the years 2005 to 2015 look like
if we were to extend the Hougen analysis?
Principles
The first valuable lesson to emerge from the workshops
was a set of principles that captured well the consensus of
the group. These included:
F Changes in science and the marketplace call for
extensive changes to the chemical engineering
curriculum
B The enabling sciences are: biology, chemistry, physics,
mathematics
B There is a core set of organizing chemical engineering
principles
Molecular transformations, multiscale
analysis, systems
0 Molecular-level design is a new core
organizing principle
] Chemical engineering contains both product and
process design
B There is agreement on the general attributes of a
chemical engineer
Two of these elements need elaboration: the core organiz-
ing principles and the attributes of a chemical engineer.
Organizing principles
In order to arrive at a picture of the curriculum we began
by enumerating the content-rather than the labels-that
chemical engineering graduates should understand and be able
to use. By then looking at the linkages and interconnections
among these content elements, three organizing principles
for the chemical engineering curriculum emerged. These are
molecular transformations, multiscale analysis, and systems
analysis and synthesis.
At the heart of chemical engineering is the manipulation of
molecules to produce desired processes and products. This is
encompassed by the organizing principle of molecular trans-
formations. Our students must recognize by both qualitative
reasoning and quantitative computation that properties can
be changed by changing structure. Molecular changes can be
architectural, for example by forming or breaking covalent
bonds or by secondary or tertiary interactions to form super-

Chemical Engineering Education











The Next Millennium in ChE
s.__________________________________________


structures. Or molecular changes can be conformational, for
example in the orientation and stretching of polymer mol-
ecules to change mechanical properties or in the folding of
proteins. Chemical engineers need to understand the equilib-
rium properties of these molecular systems and the rates of
reaction or structural changes. Finally our graduates should
be equally comfortable with the manipulation of biological
molecules as with the small organic and large synthetic poly-
mer molecules that have been the traditional domain of chemi-
cal engineering.
It is not sufficient for chemical engineers to manipulate
matter at the molecular level. In addition we must be able to
connect behavior at the small scale with that at the large scale.


entire globe or large regions of the globe in which we desire
to regulate sources of emissions in order to control concen-
trations of undesirable chemical species.
In summary, chemical engineers leverage knowledge of mo-
lecular processes across multiple-length scales in order to
synthesize and manipulate complex systems comprising pro-
cesses and the products they produce. These new principles
are summarized in Figure 3.

Attributes
Engineers are fundamentally problem solvers, seeking to
achieve some objective of design or performance among tech-
nical, social, economic, regulatory, and environmental con-


For example, we
need to be able to
take the molecu-
lar-level under-
standing of the ki-
netics of a chemi-
cal reaction and
use this to design
an appropriate re-
actor for commer-
cial use. Or we
need to be able to
exploit the under-
standing of poly-
mer conformation
on properties in or-
der to design a
commercial spin-


* Molecular Scale Transformations
chemical & biological
physical: phase change, adsorption, etc
* Multi-Scale Descriptions
from sub-molecular through "super-macro"
for physical, chemical and biological
processes
* Systems Analysis & Synthesis
at all scales
tools to address dynamics, complexity,
uncertainty, external factors


Old core does
not integrate
molecular
concepts


Old core covers only
macro to continuum,
physical and
chemical


Old core primarily
tied to large scale
chemical processes


Figure 3. New organizing core principles for use in integrating the curriculum.


ning process to make high-strength fibers. The organizing prin-
ciple of multiscale analysis addresses the application of chem-
ical engineering principles over many scales of length and time.
It is not the goal of multiscale analysis to have students work
from the atomic or molecular level up to the macroscopic
level in every problem. Rather, it is important that students
develop the ability to recognize, in any given problem,
what the important length and time scales are for analysis
and design.
Ultimately chemical engineers cannot be successful unless
we can take the knowledge of molecular processes and the
ability to manipulate these across appropriate scales and in-
tegrate these into functional systems. The organizing prin-
ciple of systems analysis and synthesis deals with the tools
for synthesis, analysis, and design of processes, units, and
combinations of these. The systems of importance to chemi-
cal engineers cover a range of scales. They could be single
cells in which we manipulate and control metabolic pathways
to produce desired chemical products, or they could be the


straints. Chemical
engineers bring par-
ticular insights to
problems in which
the molecular na-
ture of matter is im-
portant. As educa-
tors we cannot teach
students everything
that might be en-
countered; instead
we aim to equip
graduates with a
confident grasp of
fundamentals and
engineering tools,
enabling them to
specialize or diver-


sify as opportunity and initiative allow. We seek in our cur-
riculum to develop critical thinking and problem solving
skills, especially for open-ended problems and those with
noisy data or uncertain parameters; to cultivate professional
attributes including oral and written communications skills;
to broaden the technical base of the students by including
examples from a variety of industries; and to cultivate an in-
stinct for lifelong learning and an awareness of the social
impacts of engineering and technology. The need for agile,
inquisitive, and fearless engineers is strongly reinforced in
the Molecular Frontier report on chemical sciences and en-
gineering,'4' which points out that the cutting-edge knowl-
edge of chemical engineering practice across industries is
changing constantly, as are global networks of technology
development.
In working to create a curriculum for the future, it is our
challenge to set a national vision for chemical engineer-
ing graduate practice beyond the norm, at the level de-
scribed by several national commissions on engineering


Spring 2006











The Next Millennium in ChE


education that envision engineering graduates who are
able to use fundamental knowledge of science and engi-
neering in a flexible and creative manner. The Molecular
Frontier report141 envisioned future graduates who can
meet the following challenges:
F Understand the basic chemistry of traditional
chemical processes, living systems, advanced
materials, and environmental control.
] Synthesize and manufacture any new substance that
can have scientific or practical interest, using
compact synthetic schemes and processes with high
selectivity for the desired product, and with low
energy consumption and benign environmental effects.
] Revolutionize design of chemical processes to make
them safe, compact, flexible, energy efficient,
environmentally benign, and conducive to the rapid
commercialization of new products.
F Understand and control, to the limits of current
knowledge and tools, how molecules react over all
time scales and the full range of molecular size.
F Develop unlimited and inexpensive energy, with new
ways of energy generation, storage, and transporta-
tion to pave the way to a truly sustainable future.
B Communicate effectively to the general public the
contributions that chemical engineering makes to
society.
F Be able to work in an interdisciplinary team of
scientists, engineers, and production personnel to
bring new substances from lab to production to
market.

A Draft Curriculum


The curriculum must engage stu-
dents in the subject matter of chemi-
cal engineering and its use, and culti-
vate along the way that mix of at-
tributes that characterizes the engineer.
To accomplish these goals we envision
a four-year structure that emphasizes
the themes of chemical engineering, in-
tegrates the contents of these themes
into a flexible and strong understand-
ing, and exercises the skills we want
to develop. This structure is versatile,
admitting a variety of materials and
modes of presentation, and is thus
adaptable to a range of cultures, re-
sources, and facilities found among
chemical engineering departments.
I do not have a finished structure of


Freshman


a curriculum to present; we are not yet that far along. At the
third workshop held on Cape Cod, however, we developed a
draft curriculum as a "proof of concept" to convince our-
selves that this was possible. Shown in Figure 4 is the layout
for a curriculum that develops the three organizing prin-
ciples-molecular transformations, multiscale analysis, and
systems analysis and synthesis-in parallel throughout the
undergraduate years, and shows how the three themes are
integrated in chemical engineering practice.
The content must also be integrated horizontally through
time, so that each principle is clearly developed. It is impor-
tant to provide many opportunities for repetition of key
ideas, concepts, and tools as the students move through
the four years of curriculum. The reinforcement of these
key elements should also be accompanied by a systematic
movement from simple to complex topics as the curriculum
proceeds. Content must also be integrated vertically at given
times in order to avoid compartmentalization. One way to
achieve this vertical integration is to use part of each year
for case studies, projects, or laboratories that cut across
the three themes. For example, each theme in the core
curriculum could be presented in one-and-a-half-semes-
ter subjects. In the latter half of the spring semester each
year, students could work in teams on intensive, integrated
laboratory or design projects that enable them to take the ma-
terial learned that year and apply it in projects developed by
industry/academic project members. In this way, both the
teaching and learning of the integrated core would be ad-
dressed. Integration could be further enhanced by a small-
group seminar series (possibly appended to an existing sub-
ject) that develops important abilities of social awareness,


Soph


Junior


Senior


Enabling Molecular-Scale Transformations
Courses Molecular Basis Molecular Basis of Reactions Special Topics
of Thermo Molecular Basis of Properties (Electives)
- Physics Classfctn of Molecules and Constitutive Eqns
- Chemistry
- Biology :
-Math Multi-Scale Analysis Beaker to Plant:
- Mat'ls Sci Interfaces and Assemblies Multi-Scale Descriptions Principles of Product &
- Eng/Comm Homogeneous Reactor Eng of Reactive Systems Process Des.
- Bus/Mgt


Chem Eng: Intro to Systems
The Frosh


Systems
Intro to Molecular Systems


Systems &
The Marketplace


Experience l

Figure 4. An example layout of a curriculum.


Chemical Engineering Education











The Next Millennium in ChE


professional ethics, communication, business development
and professional practice, and economics. By focusing each
seminar series on these important nontechnical abilities, stu-
dents would hone these skills and be better able to apply them
as part of their spring semester integrated project work.
In summary, the material within an academic term, as well
as across the four years, must proceed from simple to com-
plex. Fundamentals must be illustrated with applications, and
examples must range from the simple demonstration to the
challenge of complex design or system manipulation. Finally,
students must be engaged actively with this material. At the
end, the curriculum must add up to a complete picture of
chemical engineering. The detail given in each principle block
suggests an order of topics. Detailed definition of these blocks
is the subject of ongoing workshops.

CONCLUDING REMARKS
This paper proposes a vision for chemical engineering edu-
cation for the future-for 2015 and beyond. To return to the
Hougen analysis of the chemical engineering curriculum
shown in Figure 1, I am suggesting a structure and focus for
Decade XI as illustrated in Figure 5. Because we have not
engaged in substantial curriculum revision in 45 years, I be-
lieve that we are best served by beginning with a clean slate.
For outflow, I suggest the entire current curriculum. This is
not to say that there are not key elements of what we teach
today that should be retained, but rather everything in the
existing curriculum must compete with new ideas to win a
spot in the new curriculum. As illustrated in the figure, the
Decade XI curriculum would be organized around the orga-
nizing principles of molecular transformations, multiscale
analysis, and systems analysis and synthesis.


INFLOW


Molecular
engineering
Systems analysis [
Biology
Product


PRINCIPAL
DEVELOPMENTS

2015

DECADE XI

Molecular transformations
Multi-scale analysis
Systems view

2005


OUTF


Figure 5. The proposed extension to Hougen's chart.


This radically different curriculum would produce more
versatile chemical engineers, who are needed to meet the chal-
lenges and opportunities of creating products and processes,
manipulating complex systems, and managing technical op-
erations in industries increasingly reliant on molecular un-


The opportunities for reform
in chemical engineering curricula are
so compelling and broad that

an appropriate response requires

wide-ranging participation
across the entire discipline.


derstanding and manipulation. Another benefit of the new
curriculum is that it reconnects undergraduate education with
ongoing research in chemical engineering in a way that has
not been present for the past 40 years. This reconnection will
serve us well as an engineering discipline in attracting the
best and brightest students and in reopening the path to con-
tinual renewal of the curriculum.

ACKNOWLEDGMENTS
In writing this paper I have drawn very heavily on the col-
lective thinking at the Frontiers Workshops. It is impossible
to emphasize too strongly how much we have to learn from
one another as we move forward in this great adventure. I
want to give special thanks to the participants who synthe-
sized summary reports at each of these workshops-Nick
Abbott, Jeff Reimer, Jim Rawlings, Mike Thien, Greg McRae,
and Bill Green-and to Barry Johnston, who pre-
pared all of the material for the Frontiers Web site
including the excellent executive summaries. Finally
I thank Jeannette Gerzon who has ably helped or-
ganize and facilitate these workshops to help us
LOW be productive.

REFERENCES
1. AIChE Career Services, Initial Placement Survey. Data
shown are from 2003; similar data for 2002 are accessible at
placement.htm> (2003)
2. Hougen, O.A., "Seven decades of chemical engineering,"
Chem. Eng. Prog. (1977)
3. Proceedings of CCR/NSF Workshops on Frontiers in
Chemical Engineering Education, riculum/> (2003, 2005)
4. NRC, National Research Council, Board on Chemical Sci-
ences and Technology, Beyond the Molecular Frontier;
Challenges for Chemistry and Chemical Engineering, Na-
tional Academies Press (2003) 0


0
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co
c-
a
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CD
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SThe Next Millennium in ChE












TEACHING ENGINEERING

IN THE 21ST CENTURY

WITH A 12TH-CENTURY TEACHING MODEL:



HOW BRIGHT IS THAT?







RICHARD M. FIELDER
North Carolina State University Raleigh, NC 27695-7905


If you took a stroll down a hall of the University of Bolo-
gna in the 12th century and looked into random door-
ways, you would have seen professors holding forth in
Latin to rooms full of bored-looking students. The profes-
sors would be droning on interminably in language few of
the students could understand, perhaps occasionally asking
questions, getting no responses, and providing the answers
themselves. You might see a few students jotting down notes
on recycled parchment, a few more sneaking occasional bites
of the cold pizza slices concealed in their academic robes,
some sleeping, and most just staring vacantly, inwardly curs-
ing the fact that iPods would not become readily available
for another 800 years. Toward the end of the lecture, one stu-
dent would ask "Professore, siamo responibili per tutta questa
roba nell'esame?" and that would be the only active student
involvement in the class. Eventually the class would be re-
leased, and the students would leave grumbling to each other
about the 150 pages of reading assigned for the next pe-
riod and expressing gratitude for the CliffsNotes version
of the text.


American engineering education doesn't exactly follow that
model. For one thing, the only engineering professor in the
Western Hemisphere-and maybe in the world-who could
lecture in Latin was Rutherford Aris, and he's deceased. Hard
drives have replaced parchment, baseball caps and jeans have
replaced caps and gowns, and (this is a huge difference) stu-
dents in Bologna actually had a lot of power, including the
responsibility of hiring professors and the right to fire them
if their performance was considered unsatisfactory. Leaving
those differences aside, however, the fact is that things haven't
changed all that much since the 12th century. If you walk
down the hall of an early 21st-century engineering school
and look into random doorways, there's a good chance you'll
see the descendants of those Bolognesi staring vacantly,

Richard M. Felder is Hoechst Celanese Professor Emeritus of Chemi-
cal Engineering at North Carolina State University. He received his
B.ChE. from City College of CUNY and his Ph.D. from Princeton. He
is coauthor of the text Elementary Principles of Chemical Processes
(Wiley, 2005) and codirector of the ASEE National Effective Teach-
ing Institute.


Copyright ChE Division of ASEE 2006
Chemical Engineering Education










The Next Millennium in ChE


snacking, and sleeping as their professors drone on inces-
santly in what might as well be Latin and fill the board or
projector screen with Latin and Greek symbols that have little
or no obvious relevance to anything the students know or
care about.
Twenty years ago that's all you would have seen in those
classrooms, with very few exceptions. Now, however, in some
departments at some schools you can find a significant num-
ber of classrooms in which other things are happening. You
might get the first signal of a difference before you ever get
to the doorway, when from down the hall you hear things
that are never heard in a traditional engineering classroom-


sounds of conversation, discussion, and argu-
ment, possibly punctuated by laughter, alter-
nating with periods of silence. If you look into
the room for awhile you would see traditional
classroom moments alternating with brief pe-
riods in which students are doing things indi-
vidually or in pairs or small groups-answer-
ing questions, completing the next steps of
derivations or problem solutions, troubleshoot-
ing, predicting, estimating, critiquing, inter-
preting, modeling, designing, formulating
questions, and summarizing. At any given mo-
ment the professor might be in front of the class
lecturing and answering questions, or quietly
observing the activity, or wandering around
the room interacting with individual students
and student groups. Unlike the situation in the
traditional classroom, many people-includ-
ing the professor-would appear to be enjoy-


only occur when the students had established a need to know
something to progress with their work.
So why the change? What is the answer to the traditional
professor's traditional defense of tradition: "It's been done
this way for decades or centuries and has worked fine," or
implicitly, "This is how I was taught, and look how well I
turned out!"
There are several answers, which would take much longer
to present completely than I have in this little piece, so I'll
only give brief suggestions of what they are and point to ref-
erences where the whole story can be found. First, if "work-


If you
have been
firmly
entrenched
in the
traditional
paradigm
I would
encourage
you to try
branching out,
but I would also
suggest taking
it easy.


ing themselves. Also unlike the traditional classroom, most
of the students enrolled in the course would actually be there.
If you inquired further into how courses are run in that de-
partment, you would see further evidence of two competing
models-one that would seem familiar to our 12th-century
scholars and one dramatically different. In one set of courses,
the professor would spend a great deal of class time lecturing
on the basic facts, formulas, and problem-solving algorithms
that comprise the course material, and would then give as-
signments and tests calling on the students to demonstrate
their ability to recite the facts, execute the formulas, and imple-
ment the algorithms. In the other courses, the students would
be presented with problems before they are told everything
they need to know to determine the solutions. They would
then work-sometimes individually and sometimes in
teams-to identify what they know and what they need to
find out, do research, formulate and test hypotheses, and ar-
rive at solutions. The professor would still be there to pro-
vide information and guidance, but formal instruction would


ing fine" means turning out excellent engineers
who have made brilliant creative contributions
to industry and society, that has certainly hap-
pened over the centuries. The issue, however, is
whether it happened because of traditional higher
education or despite it. There is compelling evi-
dence that the latter may be the case. Take Eu-
rope, for example. In the traditional European
system of higher education that has prevailed for
centuries, the professor is a godlike figure who
lectures to students and has little or nothing more
to do with them. The students may or may not
choose to attend the lectures-if the professor is
a particularly skilled lecturer they attend, other-
wise most don't.
You might argue that this system led to the
wondrous scientific advances of the Renaissance
and the Enlightenment and the giant technologi-
cal leaps of the industrial revolution, but I would


quarrel with that argument. If you admit only the cream of
the crop of a nation's youth (which universities in Europe
and America did until fairly recently), it almost doesn't mat-
ter what you do or don't do in the classroom. You could sim-
ply hand out syllabi and lists of references and tell the stu-
dents that they will be examined at the end of the year, and
then do nothing else-no lectures, no homework, no tests
except the final exam-and most students would manage to
learn the material and pass the exam, and the few geniuses
among them would go on to make their brilliant contribu-
tions, especially if they were clever enough to apprentice
themselves to masters from the previous generation.
In short, professors who provide only traditional lecture-
based instruction are largely irrelevant to the real learning
process for top students. Good lecturers can certainly enrich
their classroom experience, but they will learn with or with-
out that enrichment. On the other hand, if you are trying to
educate a broad segment of the population-as we are now
doing in the United States-many students can't make it with


Spring 2006











The Next Millennium in ChE


only the support that traditional instruction provides, and the
consequence is the attrition of 50% and higher that we rou-
tinely see in engineering.
Another argument for change is that unlike our anteced-
ents in the Middle Ages, we now know a lot from cognition
research about how people learn and the instructional condi-
tions that facilitate learning [see the reference by Bransford,
et al., in the bibliography], and everything we know supports
the proposition that the traditional lecture-homework-test
paradigm of engineering education is simply ineffective-
good students learn despite it, and weaker students who could
make excellent engineers frequently cannot survive it. The
alternative instructional environment supported by the re-
search is quite different. Here are some of the things teachers
do in that environment, contrasted with what they do in the
traditional approach.
T T: (Traditional) Establish a syllabus assuming
that all necessary prerequisite knowledge is
known, and march through it.
A: (Alternative) Find out at the beginning of a
course what most of the students know and don't
know and what misconceptions they have about
the subject, and start teaching from that point.
(This approach is known as constructivist
teaching.)

F T: Assume all students with the ability to
succeed in the profession for which they are
being educated are basically alike (specifically,
like the professor) and learn in the same way,
and teach accordingly.
A: Recognize that good students vary consider-
ably in motivation, cultural background, inter-
ests, and learning style, and teach accordingly.

I T: Focus on facts, formulas, and algorithms for
solving well-structured closed-ended single-
discipline problems.

A: Supplement the traditional content with
training in critical and creative thinking, meth-
ods of solving ill-structured open-ended multi-
disciplinary problems (which tend to be what
practicing engineers spend most of their time
dealing with), and professional skills such as
communication, teamwork, and project manage-
ment.

I T: Cover basic knowledge (facts, algorithms,
and theories) in lectures, then assign problems


that call for implementation of the knowledge,
then illustrate the knowledge in laboratories.

A: Recognize that students learn best when they
perceive a need to know the material being
taught. Start with realistic complex problems, let
students establish what they know and what they
need to find out, and then guide them in finding
it out by providing a combination of resources
(which may include mini-lectures and integrated
hands-on or simulated experiments) and guid-
ance on performing library and Internet research.
This is inductive teaching and has a number of
variations, including problem-based learning,
project-based learning, guided inquiry, discovery
learning, and just-in-time teaching.

I T: In class, present information, derive formulas,
and illustrate problem-solving procedures in
lectures, boardwork, and overheads or
PowerPoint images, occasionally asking
questions and responding to questions stu-
dents might ask.
A: In addition to lecturing, have students work
individually and in small groups on brief course-
related activities, such as answering questions,
setting up problem solutions, completing steps in
derivations, interpreting observations or experi-
mental data, estimating, predicting, brainstorm-
ing, troubleshooting .... Call on several
students for responses at the conclusion of each
activity, then invite volunteers to provide more
responses to open-ended questions, and proceed
with the lesson when the desired points have
been made. This is active learning.

I T: Require students to do all of their work
individually.

A: Assign a combination of individual work and
teamwork, structuring the latter to provide
assurances of individual accountability for all the
work done and following other procedures
known to promote good teamwork skills
(including communication, leadership, project
management, time management, and conflict
resolution skills). This is cooperative learning.

I T: Tell the students they are responsible for
everything in the text, lectures, and homework,
and make up exams that draw on those sources,
including some problems with twists that the


Chemical Engineering Education











The Next Millennium in ChE


students have not seen before and have to figure
out on the spot. (Those problems are there to see
if the students "know how to think.") It is up to
the students to guess what the instructor thinks is
important enough to include on a test.

A: Write comprehensive instructional objectives
that list the things the students should be able to
do (identify, explain, calculate, model, design,
critique ... ) to demonstrate that they have
satisfactorily mastered the knowledge and skills
the instructor wants them to master, including
high-level thinking and problem-solving skills.
Make the objectives available to the students,
ideally in the form of study guides for tests.
Design in-class activities and homework to
provide practice in the desired skills, and make
the tests specific instances of a subset of the
instructional objectives.

Instructors who are unfamiliar with the latter approach
imagine that they will have to list thousands of objectives
to be comprehensive, but this is not the case-a two-sided
sheet of paper is normally sufficient to list all of the ob-
jectives that might be drawn upon to construct a
midsemester test.

Entire articles and books can be-and have been-written
on each of the given alternative teaching methods, describ-
ing how to implement them and summarizing the research
base that demonstrates their superiority to the traditional ap-
proach. The bibliography at the conclusion of this paper sug-
gests starting points for interested readers.

If you have been firmly entrenched in the traditional para-
digm I would encourage you to try branching out, but I would
also suggest taking it easy. Going directly from a traditional
teaching model to a full-bore active/cooperative/problem-
based learning paradigm starting next Monday is probably
not a good idea-the amount of preparation required and the
student resistance that might erupt could be overwhelming.
Better approach is to make the change gradually, perhaps
by doing a few small-group exercises in lectures, using a
problem-based approach to teach one or two topics, and
writing instructional objectives for one midterm test. In
subsequent courses, increase your use of the new meth-
ods, never departing too much from your comfort zone,
and you should see your students' learning steadily increas-
ing. After all, it took us 800 years to get from Bologna to
where we are now; if it takes you a few years to get where
you want to be, the sky won't fall.


BIBLIOGRAPHY
Effective Teaching Methods and the Research that
Supports Them
1. Bransford, J.D., A.L. Brown, and R.R. Cocking, eds., How
People Learn: Brain, Mind, Experience, and School, Wash-
ington, DC: National Academy Press, 2000. Online at www.nap.edu/html/howpeoplel/>
2. Felder, R.M., D.R. Woods, J.E. Stice, and A. Rugarcia, "The
Future of Engineering Education: 2. Teaching Methods that
Work," Chem. Eng. Ed., 34(1), 26-39 (2000). Online at /www.ncsu.edu/felder-public/Papers/Quartet2.pdf>
3. Woods, D.R., R.M. Felder, A. Rugarcia, and J.E. Stice, "The
Future of Engineering Education: 3. Developing Critical
Skills," Chem. Eng. Ed., 34(2), 108-117 (2000). Online at

Active Learning
4. Felder, R.M., "Random Thoughts" columns in Chemical En-
gineering Education:
(a) "Learning by Doing," public/ColumnslActive.pdf>
(b) "It Goes Without Saying," felder-public/Columns/WithoutSaying.pdf>
See also CooperativeLearning.html>
5. Prince, M., "Does Active Learning Work? A Review of the
Research," J. Engr. Ed., 93(3), 223-231 (2004)
Cooperative Learning
6. Felder, R.M., and R. Brent, Cooperative Learning in Techni-
cal Courses: Procedures, Pitfalls, and Payoffs, www.ncsu.edu/felder-public/Papers/Coopreport.html>. See
also < h ttp : // w w w. n csu edu fielder -p ubic
Cooperative Learning.html>
7. Two meta-analyses of research on cooperative learning vs. tra-
ditional instruction can be found at
(University of Minnesota) and

(University of Wisconsin)
8. A Web site with links to CL-related papers and many CL sites
is Ted Panitz's
Problem-Based Learning
9. Prince, M.J., and R.M. Felder, "Inductive Teaching and Learn-
ing Methods: Definitions, Comparisons, and Research Bases,"
J. Engr. Ed., in press (2006)
10. Duch, B.J., S.E. Groh, and D.E. Allen, The Power of Problem-
Based Learning, Sterling, VA: Stylus (2001)
11. University of Delaware Problem-Based Learning Clearing-
house, . Ted Panitz's site
() and Deliberations, a site
managed by London Metropolitan University ( www.londonmet.ac.uk/deliberations/problem-based-learning/>)
are good sources of both information about PBL and links to
other PBL-related sites. O


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The Next Millennium in ChE


A DIFFERENT


CHEMICAL INDUSTRY





E.L. CUSSLER
University of Minnesota Minneapolis, MN 55455


An Altered Industry. The chemical industry today is
completely different from the chemical industry of
25 years ago. The clearest evidence comes from the
jobs taken by graduating chemical engineers. Twenty-five
years ago, 80 percent of these graduating students went to
the commodity chemical industry, exemplified by Dupont,
Exxon, Shell, and Dow. Occasionally they went to interna-
tional companies such as Bayer and ICI, though this was less
common. The remaining 20 percent were roughly divided
into equal groups. Some, perhaps 10 percent, went to prod-
uct-oriented businesses such as PPG, Upjohn, or 3M. A simi-
lar number, perhaps another 10 percent, went to everything
else, including consulting, government, and academia. This
older chemical industry, dominated by large-commodity
chemical companies, was very familiar and dependable.
Today, as Figure 1 shows, the situation is completely dif-
ferent. The percentage of graduates going to the commodity
chemical companies has dropped dramatically, perhaps to a
quarter of the total. Simultaneously, the percentage going to
consulting has risen to around another quarter. This consult-
ing includes functions such as process engineering, now con-
tracted out rather than performed within the engineering labo-
ratories of the commodity chemical companies.
The bulk of new graduates, however, now goes to indus-
tries where products are most important. Some of these prod-
ucts, such as pharmaceuticals, are familiar; others, such as
foods, have existed previously but have not involved signifi-
cant numbers of chemical engineers; still others such as elec-
tronics represent new efforts.

WHAT PRODUCTS ARE IMPORTANT
In this altered chemical industry, we must first ask what
are the products that we are going to produce. I believe there
are three types of these products, each with different charac-
teristics. The first and most obvious are the familiar com-


modities-the same products which used to dominate the
chemical engineering enterprise. The key for producing these
new products is their cost. Styrene produced by Dow and
styrene produced by BASF are chemically identical; the
issue is who can produce large quantities at the lowest
possible price.
The second and third types of products may be less famil-
iar. The second type involves molecules with molecular
weights of 500-700 and with specific social benefits. The most
obvious examples are pharmaceuticals. The key to the pro-
duction of pharmaceuticals is not their cost but rather their
time to market, i.e., the speed of their discovery and produc-
tion. The first-to-market tends to get at least two-thirds of the
eventual sales for the molecule, even after patents on the par-
ticular molecule expire. These products are normally not made
in dedicated equipment but rather in whatever reactors are
available at that specific time. Thus, process optimizations
tend to be less important than questions of scheduling: If the
equipment is being used for many different products, when
can you get in to make yours?
The third product type includes those for which the value
is added by processing to make a specific nanostructure. The
key to these products is their function. For example, I don't


Edward L. Cussler, currently distinguished institute professor at the
University of Minnesota, received the B.E. with honors from Yale
University in 1961, and his M.S. and Ph.D. in chemical engineering
from the University of Wisconsin in 1963 and 1965, respectively
Soon after, he went to teach in the Department of Chemical Engi-
neering at Carnegie Mellon University. In 1980, Cussler joined the
faculty at the University of Minnesota. He is the author of Multicom-
ponent Diffusion, published in 1976, and Diffusion, published in
1984 with a second edition published in 1997 He is the co-author of
Membrane Separation Systems, Bioseparations, and most recently,
Chemical Product Design, the English edition of which was published
in 2001.

Copiright ChE Division of ASEE 2006


Chemical Engineering Education










The Next Millennium in ChE


care why my shoes shine after I have applied polish; I only
care that they do shine. It is the shine, not the molecule that
produces the shine, that is important. Customers are often
willing to pay a premium for such a function, be it in a coat-
ing, in a food, or in a cleaner.
I find it helpful to think about these three types of products
using the summary shown in Table 1. For commodity prod-
ucts, the key factor as stated previously is the cost of the prod-
uct. The basis for producing the product will continue to be
unit operations-unit ops-the familiar core of chemical en-
gineering. Our action in this area should be to sustain the
commodity industry. We are certainly not currently carrying
out unit operations in the best way possible, but we are prob-
ably close to the limit of what is economically attractive.
With the key factor of the second type of molecular prod-
ucts being time to market, the major cost of products of this
type, such as drugs, is not the process engineering but the
cost of their discovery. At best, only one in a thousand drug
candidates is commercially successful. This enormous drop-
out rate is the reason drugs are expensive. The key to discov-
ery normally comes from chemistry and microbiology, not
from chemical engineering. As a result, it is not clear whether
traditional process engineering has a major role to play in
molecular products.
For nanostructured products, the third type, whose key fac-
tor comes from their superior function, the added value comes
from the process rather than from the chemical synthesis.
Their desired function is the shine of the polish or the clean-
ing of the detergent. Studies in this area seem to lack any
unifying intellectual core. Flavor release in food science takes
no advantage of what is known about controlled drug release
in pharmaceutics. Micelle formation in latex paint is an inde-
pendent topic from micelle formation in detergents. I believe
there is a genuine need for a general theory of nanostructured
products. Such a theory could be part of a required course
common to departments including chemical engineering, food
science, and pharmacy.

IMPLICATIONS FOR EDUCATION
Faced with this altered chemical industry, we must ask
whether the skill set currently mastered by chemical engi-
neers is appropriate for the future. This skill set consists of
three roughly equal parts, based in physics and mechanics, in
chemistry and biology, and in chemical engineering. I don't
think this skill set is inappropriate for the future. The ideas of
reaction engineering and separation processes will continue
to be central to what chemical engineers do. Within these
areas, some topics will recede and other topics will become
more important, but the core will remain.


E Commodities 0 Products ] Consult



Figure 1. Where the jobs are in chemical engineering.

I do think that there may be a partial problem with the
courses that present these topics. At the moment, these courses
are biased heavily toward the commodity chemical industry.
This bias includes such classical chemical engineering courses
as transport phenomena and thermodynamics. In the future,
new courses, including those based on biology, on polymer
science, and on product design, must become more central to
the chemical engineering curriculum. We require three such
courses at the University of Minnesota precisely because we
believe the content of those courses will better prepare our
students for the new chemical industry.
Some may find this description of a changed chemical in-
dustry depressing. I don't. I think it is simply different. For
example, it means that we may now work more on crystalli-
zation and less on fugacity, but I don't think that is a prob-
lem. In many ways, the reemergence of an emphasis on prod-
ucts and the corresponding de-emphasis of a few commodity
chemicals suggests a broader intellectual challenge for chemi-
cal engineering. That challenge is interesting. I welcome it. I
think it is exciting. And I think all of us will discover that
excitement together. O


TABLE 1
Three Kinds of Products
Different strategies are appropriate for different kinds of products.


Key Cost Speed Function
Basis Unit Ops Discovery f (Properties)
Action Sustain Chemistry Key Unified Theory


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Where the Jobs Are




Lh 1


2003


1975


Nanostructures


ICommodities IMolecules











The Next Millennium in ChE






CRYSTAL ENGINEERING:

From Molecules To Products


Preamble According to many contemporary scientists, engineers, policy-makers, and
business leaders, the future belongs to biotechnology, nanotechnology, and information technol-
ogy. Chemical engineering research and teaching are being changed by these fields, as dis-
cussed in this series of articles and elsewhere. Change is happening at a measured pace, and
biology has joined chemistry, physics, and mathematics as a fourth foundation discipline of the
chemical engineering curriculum. I have little to offer that has not already been said about bio,
nano, and info. However, there are other subjects that are of vital interest to society that are
squarely in the domain of chemical engineering and that have received less attention than their
worth. Among these, energy and crystalline solids rank high. I would like to say something
about both these topics, but I will confine myself to crystalline solids-particularly organic
materials. My goal is to highlight the importance of the solid state and to show how easily it can
be incorporated into the chemical engineering curriculum.




MICHAEL F. DOHERTY
University of California Santa Barbara, CA 93106-5080


Crystalline organic solids are ubiquitous as either fi-
nal products or as intermediates in the specialty
chemical, pharmaceutical, and home and personal-
care industries. Virtually all small molecular-weight drugs
are isolated as crystalline materials,"' and more than 90% of
all pharmaceutical products are formulated in particulate, gen-
erally crystalline, form.[21 Crystalline chemical intermediates,
such as adipic acid, are produced in large amounts to make
polymers and specialty products. Skin creams and other per-
sonal-care product formulations contain crystalline solids. In
most cases the properties of the crystalline solid have a ma-
jor impact on the functionality of the product as well as the
design and operation of the manufacturing process.
Crystal size (or size distribution), shape, enantiomorph, and
polymorph all influence product functionality. For example,
even a 50 micron particle in a hand cream makes the cream
feel gritty.'3' Size distribution is important in the manufacture
of beta-carotene, which is virtually insoluble in water and
only sparingly soluble in vegetable oils, and is used as a food
colorant. The color shade given to the food is determined by
the narrow size distribution, which must be in the submicron
range.'31 Crystal shape and polymorph influence solubility,
dissolution rate (which influences bioavailability), compress-


ibility (important for tabletting), and stability. The crystal
enantiomorph is of vital importance in the manufacture of
chiral materials, which has become a $150 billion industry in
recent years. The choice of solvent, along with the design
and operation of the manufacturing process, determines the
crystal properties. Moreover, crystal size, distribution, and
shape have a major impact on the design of the manufactur-
ing process since small crystals are difficult to separate from
solution, and needle-like crystals or plate-like crystals can be
difficult to filter and dry.

Michael F Doherty is a professor of chemical engineering at the Univer-
sity of California, Santa Barbara. He received his B.Sc. in chemical engi-
neering from Imperial College, University of London, in 1973, and his Ph.D.
in chemical engineering from Trinity College, University of Cambridge, in
1977 His research interests are in process design together with the asso-
ciated chemical sciences necessary to support the design activity. He has
published extensively on design and synthesis of nonideal separation sys-
tems, especially the coupling of separation with simultaneous chemical
reaction, and crystallization of organic materials from solution. He is the
holder of four patents, has published more than 150 technical papers and
one textbook, and has delivered more than 180 invited lectures. He has
served as a consultant for many multinational companies in the area of
process design and separations technology, and has served on the Cor-
porate Technical Advisory Boards for The Dow Chemical Company and
Rhone-Poulenc.


Copyright ChE Division of ASEE 2006
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The Next Millennium in ChE


Many important compounds exhibit polymorphism, i.e., the
existence of more than one crystal structure. Different poly-
morphs can have very different physical properties, includ-
ing color, hardness, and stability. Therefore, control of which
polymorph crystallizes in an industrial system is of vital im-
portance. For example, since bioavailability can vary greatly
among polymorphs of the same drug,"1 the U.S. Food and
Drug Administration requires the registration of each drug
polymorph and the strict production of only that form. It can
be difficult to control which polymorph crystallizes, even to
the extent that production output can change unexpectedly
from one form to another. This can be catastrophic, e.g., halt-
ing production until the process can be altered to produce the
original polymorph.151 Many in industry, particularly the phar-
maceutical industry, are now undertaking exhaustive poly-
morph screening to identify all possible/likely polymorphs
before beginning to scale up crystallization processes.[6'
The importance of crystal shape to processing and product
quality/functionality has been discussed in the context of
ibuprofen.'71 The primary interest in this system is the exist-
ence of high-aspect ratio needles when grown from nonpolar
hydrocarbon solvents such as hexane or heptane. Equant (i.e.,
low aspect ratio crystals with roughly equal sides) are formed
when grown from polar solvents such as methanol or etha-
nol. This was discovered by researchers at the Upjohn Com-
pany,'71 who patented the change in solvent as a process im-
provement.
The structure of this article is as follows. It begins by high-
lighting some of the advances made in the fundamentals of
crystallization during the last decade, together with recom-
mendations for where these topics can be inserted into the
curriculum. Next is a brief review of recent improvements in
CFD and population balance modeling for crystallizers. Third
are descriptions of new methods for process synthesis of flow-
sheets containing crystallization steps. Last are some recom-
mendations for incorporating crystal engineering into the core
of chemical engineering education and research.

FUNDAMENTALS OF CRYSTAL ENGINEERING
Crystal Structure
A crystal is an ordered three-dimensional array of mol-
ecules, and represents one of nature's most remarkable ex-
amples of self-assembly. This definition contains the con-
cept of periodicity. A solid material that has disordered struc-
ture, or that displays no long-range order (although it may
possess short-range order) is called amorphous.
All crystals have translational symmetry, i.e., repetition of
motifs by translational displacement in space. Each crystal
can be decomposed into a collection of unit cells, which are
the smallest structural units that re-create the entire three-
Spring 2006


A crystal is an ordered

three-dimensional array of

molecules, and represents one of

nature's most remarkable

examples of self-assembly.



dimensional crystal structure when they are repeated in space
by simple translation in every direction. Unit cells are paral-
lelepipeds, the vertices of which constitute a grid of points
called a lattice with its own periodicity and symmetry. The
unit cell also defines three sets of planes in space, each set
being parallel and equally spaced-the distance between the
planes in each set is called the interplanar spacing, which is
an important concept in crystal growth models. Within the
cell, symmetry operations relate the molecules that consti-
tute the contents of the cell. An asymmetric unit is the small-
est structural unit (e.g., a nonsymmetrical dimer, a single mol-
ecule, or part of a molecule) within which no symmetry ele-
ments operate. The collection of symmetry elements belong-
ing to a crystal structure is called a space group. Therefore, a
space group is the set of geometrical symmetry operations
that brings a three-dimensional periodic crystal into itself.
There are a total of 230 unique space groups. The number of
symmetry elements in a space group must be equal to the
number of asymmetric units in the cell.
It is important to realize that unit cells do not physically
exist in a lattice and the lattice does not physically exist in
the solid. These are mental constructs to help visualize the
solid structure. There are several different lattice arrangements
and unit cells that can be constructed-but only 14 possible
lattices that fill three-dimensional space. These lattices can
be further divided into seven crystal systems; each has a fixed
relationship between the cell's spatial dimensions and angles.
The seven systems are: cubic, tetragonal, orthorhombic, hex-
agonal, trigonal, monoclinic, and triclinic. Most organic mol-
ecules have uneven molecular shape that leads to low-sym-
metry crystal systems. The crystallographic systems with
uneven unit-cell parameters are the monoclinic, triclinic, and
orthorhombic. The majority of organic structures reported (ap-
proximately 95%) belong to these systems.
Molecules arrange themselves in crystals in such a way
that the whole spatial arrangement must belong to one of the
14 Bravais lattices. The total number of independent ways in
which molecules can decorate these lattices is 230 (corre-
sponding to the total number of independent space groups).











The Next Millennium in ChE


Fortunately, only a few of these space groups are important
in solid state chemistry. A more in-depth view of crystallog-
raphy is available from many sources, including Cullity,'81
Stout and Jensen,'9' and the International Tables for X-Ray
Crystallography.
Crystal structure and x-ray crystallography are well suited
for inclusion in the undergraduate physical chemistry se-
quence. Gavezzottil'Il has created an excellent visual intro-
duction to crystal symmetry, written in a tutorial style suit-
able for undergraduates.
Nucleation
Crystals are born by nucleation, which may be defined as
the formation of molecular solute clusters in solution that are
in dynamic contact with the solute molecules dissolved in
the solution. When the clusters reach a critical viable size
they become a crystalline particle that grows by the addition
of solute material on the crystal faces. Faces may appear or
disappear during growth depending on the relative growth
velocities of adjacent faces.
Nucleation can be divided into two types: primary and sec-
ondary. Primary nucleation is the formation of nuclei in solu-
tion whether or not suspended crystals are present. It is fur-
ther subdivided into homogeneous and heterogeneous. Ho-
mogeneous nucleation is the formation of nuclei in previ-
ously crystal-free solution. Primary heterogeneous nucleation
requires the preexistence of foreign bodies or catalytic sur-
faces in the solution. Foreign bodies can be dust particles,
nuclei of substances different from the solute, etc. Catalytic
surfaces may be roughness on the vessel walls, or a surface
that was designed specifically for this purpose, such as a com-
pressed surfactant monolayer (Langmuir) film or a self-as-
sembled monolayer. Secondary nucleation is used to describe
any nucleation mechanism that requires the presence of sus-
pended solute crystals. Secondary nucleation may take place
by several mechanisms: seeding, breakage, attrition due to
collision (collision nucleation), or removal of surface layers
through surface shear. Collision nucleation is the dominant
mechanism of secondary nucleation, whereby growing crys-
tals collide with the container walls, with a stirrer, or with
other crystals.
Homogeneous nucleation from clear solution is of special
interest because it is an important pathway in which the crys-
tal polymorph (crystalline packing structure) is created-see
the section below on Solution Mediated Polymorphism. The
classical view of this process is that it occurs from the solute
species clustering together in solution and then adopting the
ordered arrangement of the crystalline state to minimize the
free energy. The Gibbs-Thomson theory for the critical clus-
ter size, re, is also based on free energy minimization. Clus-
ters larger than r must grow in order to reduce the free en-
118


ergy of the total system solutee cluster + solution) while clus-
ters smaller than the critical size dissolve in order to reduce
the free energy of the system.
In the Gibbs-Thomson theory, it is assumed that only sol-
ute transfers to the nucleus from a supersaturated solution
(the composition of which is located in the metastable region
of the phase diagram). It is also supposed that the mass of the
nucleus phase is so small that the composition of the solution
phase is constant during the nucleation event. The total free
energy change, AG, consists of three terms: a change in bulk
free energy of the solution, a change of bulk free energy of
the nucleus, and a change of surface free energy of the nucleus.
The resulting expression for a spherical nucleus is

AG=-4-nr3 Aslute +47r2y (7)
3 vsolute

where lsolute is the difference in chemical potential of the
solute in the supersaturated solution and in the nucleus (this
term is always positive); vsolute is the molar volume of pure
solute in the nucleus phase. The chemical potential differ-
ence can be written

Absolute= RT In(l+o) (2)
where a represents the relative supersaturation (Csu"Pe"t-Csa')/Cs'.
The major assumption in Eq. (2) is that the activity coeffi-
cient of the supersaturated solution is equal to that in the satu-
rated solution-a reasonable approximation in most cases.
The leading term in Eq. (1) is always negative and represents
the decrease in bulk free energy due to phase change. The
second term in this equation contains the quantity y, which
is the surface free energy per unit area of nucleus (always a
positive quantity) and represents the increase in free energy
due to surface formation. The sum of these two terms pro-
duces a free energy plot with a single maximum that defines
the size of a critical nucleus, as shown in Figure 1 for the
alpha polymorph of the simplest amino acid, glycine, nucle-
ated from aqueous solution at room temperature.
The critical nucleus size is given by

rc= (3)
Ap solute
This theory predicts that typical values for a characteristic
length (diameter) of a critical nucleus are in the size range of
hundreds of nanometers. For a-glycine, the critical diam-
eter is approximately 600 nm. Recent computer simulations
on small molecules predict critical nucleus sizes of 3-6 nm.
The reason for the large discrepancy is currently unknown.
Using atomic-force microscopy in situ during the crystalli-
zation of the protein apoferritin from its aqueous solution,
Yau and Vekilov'" "12 have directly measured the crystalline
Chemical Engineering Education











The Next Millennium in ChE


packing structure and critical nucleus size of this material.
They found critical nucleus sizes in the range of a few tens of
nanometers (depending on the level of supersaturation). A
typical value is 40 nm for the cluster shown in Figure 2-
two orders of magnitude smaller than expected from tradi-
tional nucleation theory for large molecules. The molecular
arrangement within the nuclei were observed to be similar to
that in the bulk crystal, indicating that the crystal polymorph
is already established at these small length scales. Moreover,
the authors state, "Contrary to the general belief, the observed
nuclei are not compact molecular clusters, but are planar ar-
rays of several rods of 4-7 molecules set in one or two mono-

3D Nucleation of c-glycine
SAG (kJ) -
4*10


2"10

Sr(nm)
100 200 300 400 500

-2 10 '


Figure 1. Change in free energy as a function of nucleus
size for a -glycine grown from aqueous solution at room
temperature, where Vglycine= 46.71 cm3/mol, y= 148.1
erg/cm2, o = 0.02, and RT = 2.5 kJ/mol.


Figure 2. A flat, near-critical-sized cluster consisting of
approximately 20 apoferritin molecules.t121

Spring 2006


molecular layers. Similarly unexpected nuclei structures might
be common, especially for anisotropic molecules. Hence, the
nucleus structure should be considered as a variable by ad-
vanced theoretical treatments."
Using small-angle neutron scattering, Lefebvre, et al.,"3'
determined the critical length scales in phase separating poly-
mer blends of polymethylbutylene-polyethylbutylene. They
obtained results similar to those reported for proteins, namely,
critical diameters in the range of 20-50 nm.
Therefore, the current status of classical nucleation theory
is that it predicts critical nucleus sizes that are about two or-
ders of magnitude too high compared to the most recent mea-
surements by Balsara's group at UC Berkeley and Vekilov's
group at the University of Houston. Moreover, classical theory
does not provide the molecular arrangement within the
nucleus-this is an "input to" rather than an "output from"
the theory. There are opportunities here for major improve-
ments in nucleation theory that could have significant impact
on crystal engineering.
Nucleation is an excellent topic to include in the under-
graduate Solution Thermodynamics course. I like to teach
the two-dimensional theory in which the solid nucleus is taken
to be a rectangular lozenge of fixed thickness with variable
length and width (the number of dimensions in the theory is
equal to the number of independent lengths that are needed
to characterize the shape and size of the nucleus). This model
is much richer than the traditional one-dimensional spherical
nucleus described above, which is characterized by only one
spatial variable: diameter. In the two-dimensional nucleation
theory, the critical nucleus corresponds to a saddle-point in
the Gibbs free energy surface, which is easy to calculate and
visualize for undergraduates. Therefore, the expected nucle-
ation path corresponds to a trajectory through the free energy
landscape over a saddle-point barrier. This provides a nice
analogy to transition state theory and the reaction coordinate
over a saddle-point barrier in chemical reaction rate theory.
Moreover, it is easy to show that the shape of the critical
two-dimensional nucleus satisfies the Wulff construction for
a two-dimensional equilibrium shape. That is, the two-dimen-
sional critical nucleus attains a shape that minimizes its total
surface energy for the given (faceted) volume. Teaching this
material to undergraduates also provides a good vehicle for
explaining the difference between surface energy' and sur-
face stress." In the case of liquids, all processes of interest

SThe reversible work per unit area needed to create a siuface-if the
variation in surface area does not change the siuface density of
molecules, then the specific surface work is smiface energy.
The reversible work per unit area needed to elastically stretch a
preexisting stuface-if the variation in simface area changes the
stuface density of molecules, then the specific surface work is sur-
face stress.











The Next Millennium in ChE


involve variations in area without varying the surface den-
sity, and the surface work represents a surface-free energy.
The traditional processes involving surface energy are creat-
ing a soap bubble and cleaving a solid into two parts, while
the traditional example of a process involving surface stress
is blowing up a rubber balloon. Both types of energy are ex-
pected to play a part in creating a solid nucleus, yet there is
no theory that accounts for this. Finally, a good reason for
teaching this material to undergraduates is to show them that
not all is known, even in traditional areas of science that have
been studied for a long time.
Growth Models
Evidence suggests that crystal faces grow by one of three
mechanisms: a screw dislocation mechanism, a two-dimen-
sional nucleation mechanism, or by rough growth. It is also
known that different faces of a crystal may grow by different
mechanisms, according to the solute-solvent interactions at
the interface (surface-free energy) and the level of supersatu-
ration. At low supersaturation levels, or large surface-free en-
ergies, the screw dislocation mechanism is normally opera-
tive. The original theory, developed by Burton, Cabrera, and
Frank,"14' proposed that screw dislocations, which exist on
real crystal faces at all supersaturation levels, provide an in-
finite source of steps onto which oncoming particles can be
incorporated. According to this theory, growth occurs by the
flow of steps across the surface, which forms a spiral. Spirals
have been observed on many faces of many crystals"5"17 (see
Figure 3). At moderate levels of supersaturation, the two-
dimensional nucleation mechanism may apply. Above a criti-
cal level of supersaturation, the face is roughened and growth
proceeds at a high rate.
The BCF expression for the rate of growth normal to a sur-
face is:

Rhkl V hklhhkl (4)
RhkI ----- (4)
Yhkl
where vhkl is the lateral step velocity, hhkl is the step height,
which can be approximated by d. (the interplanar spacing)
for monolayer height, and yhk1 is the distance between steps.
Since growth occurs at kink sites (vacancies in steps where
solute growth units can incorporate-see Figure 1 in Chen
and Vekilov1I 8 for a beautiful image of kink sites on a step of
crystallized ferritin), the lateral step velocity depends mainly
on the density of kink sites. In the simplest case, molecules
along the edges of a spiral are found in one of three
microstates: a positive kink site, a negative kink site, and no
kink site. The energy for each of these microstates can be
calculated, and if we assume that they occur in their most
probable configuration, then the probability of finding a kink
site along an edge is given by the Boltzman distribution. This


Figure 3. Four consecutive images of a spiral growing
from a screw dislocation on a calcite crystal face.t17


Figure 4. Reported and predicted morphologies for
a -glycine crystallized from aqueous solution.
(a) Experimentally grown crystal from Boek, et al.1271
(b) Predicted shape using the form of the BCF model in
Eq. (4) with a dimer growth unit. (c) Shape predicted by
Eq. (4) using a modified monomer growth unit.1261


Chemical Engineering Education


(120) ii

(110


4020)
(c)











The Next Millennium in ChE
^__________ _________________________


result provides a nice link between elementary statistical
mechanics and the kinetics of crystal growth. (In my experi-
ence, if you want to teach undergraduates the methods of sta-
tistical mechanics so that they understand, use the textbook
by Kittel and Kroemer."91)
Crystal Shape
It is well known that crystals grow in a variety of shapes in
response to both internal and external factors. Some of these
factors can be manipulated (e.g., solvent type, solution tem-
perature, and supersaturation) by crystal engineers to steer
crystals toward a target shape or away from undesired shapes.
Experiments performed on the growth of crystals from
spherical seeds have shown that flat faces appear during
growth. Some of the faces that appear eventually disappear,
while others grow in size, eventually leading to a fully facet-
ted stationary (steady state) shape. The shape of crystals at
thermodynamic equilibrium can be determined using Gibbs'
approach of minimality of the total surface-free energy per
unit volume. This thermodynamic equilibrium condition leads
to the Wulff construction to determine crystal shape

Yi
--constant, i= 1,...,N (5)
hi

where yi is the specific surface-free energy of face i, hi is the
perpendicular distance between the origin and face i, and N is
the number of faces. Only very small particles (nanoparticles)
can undergo rapid shape change to reach equilibrium, during
which the size change is not substantial. For larger particles,
however, the number of elementary transport processes that
have to occur to achieve significant changes in shape is so
large compared with the lowering of the surface-free energy
that the rate of equilibration becomes negligible.1201 For crys-
tals grown from seeds, steady state shapes (that have self-
similar growth) are therefore observed more often than the
equilibrium shapes. Wulff's condition was modified by
Chernov 11 (also see Cahn, et al., '22) to determine the crystal
shape at steady state, given as:


constant, i=l,...,N


where R, is the perpendicular growth velocity of face i. As
noted in the previous subsection, many mechanisms and mod-
els are available to estimate the perpendicular growth veloci-
ties of facets, but in most solution crystallizations only one
model-the screw dislocation model [BCF model, Eq. (4)]-
has the proven capability to correctly estimate the relative
growth rates of crystals grown from solution. A comprehen-
sive validation of this modeling approach is given by Liu, et


al.,'213 Winn and Doherty,r24'25' and Bisker-Leib and Doherty.[26]
The shapes of many organic crystals have been successfully
predicted with this approach, e.g., urea grown from aqueous
solution, ibuprofen grown from methanol and from hexane,
adipic acid grown from water. Figure 4 compares the experi-
mental and predicted steady state growth shapes of a glycine
crystallized from aqueous solution. This is a particularly sen-
sitive test of the approach due to the complex network of
hydrogen bonds that are formed in the solid state. Although
there are many aspects of this modeling approach that need
improvement, such as a priori identification of the nature of
the growth units that incorporate into the growing crystal
faces, the approach is already sufficiently well developed
for immediate application to engineering design.
Although significant progress has been made recently on
predicting the steady state shapes of organic materials crys-
tallized from solution, there is less to report on the important
related matter of predicting shape evolution from an initial
seed or nucleus shape through to the final steady state shape.
The only evolution models reported in the literature are for
two-dimensional crystals, which apply to materials that crys-
tallize in flat plate-like shapes, such as succinic acid grown
from water (flat hexagonal crystals), and L-ascorbic acid (vi-
tamin C) grown from water (flat rectangular crystals). The
dynamics of shape evolution for three-dimensional crys-
tals are quite complicated as faces, edges, and vertices
appear or disappear during growth. The definitive study
is yet to be done.
Although some may disagree with me, I think the topic of
crystal growth and crystal shape as outlined above is good
material for inclusion in an undergraduate transport course.
Solution Mediated Polymorphism
The phenomenon of polymorphism-a solid crystalline
phase of a given compound resulting from the possibility of
at least two crystalline arrangements and/or conformations
of the molecules of that compound in the solid state-has
been known to exist for over two centuries.[J28 Despite this,
its prevalence presents one of the greatest obstacles to the
solids-processing industry today. To obtain the desired prop-
erties of the product, the correct polymorph must be obtained
since they have different physical properties: melting points,
solubilities, bioavailabilities, enthalpies, color, and many
more. Differences between polymorphs are crucial for indus-
tries such as the pharmaceutical industry, where differences
in dissolution rates between two polymorphs may mean that
one polymorph is a potential product because of its high dis-
solution rate (high efficacy) while another is not due to its
negligible dissolution. A dramatic example of this phenom-
enon is provided by the Ritonavir polymorphs.[51


Spring 2006











The Next Millennium in ChE


Paracetamol (acetaminophen) is an analgesic drug that is
used worldwide as a pain reliever. Due to its commercial
importance, acetaminophen has been subject to many crys-
tallization experiments and, in particular, polymorph studies.
Paracetamol has three known polymorphs. Monoclinic
paracetamol is the thermodynamically stable form at room
temperature and, therefore, it is the commercially used form.
Unfortunately, it is not suitable for direct compression into
tablets, since it lacks slip planes in its structure, which are
necessary for the plastic deformation that occurs during com-
paction. Consequently, it has to be mixed with binding agents,
which is costly in both time and material. Crystallization of
the orthorhombic polymorph (form II) of paracetamol from
solution is more desirable since it undergoes plastic defor-
mation and is therefore suitable for direct compression. In
addition, it is believed to be slightly more soluble than form
I. Until 1998 there was no reproducible experimental proce-
dure available for the crystallization of form II from solu-
tion. The only method that
had been reported for bulk
preparation of form II was to
grow it as polycrystalline
material from fused form I.
In 1998, Gary Nichols
from Pfizer and Christopher
Frampton from RocheE291 de-
scribed a laboratory-scale
process to crystallize form II
from solution. They found
that the orthorhombic poly-
morph of paracetamol could
be crystallized from super-
saturated solution of indus-
trial methylated spirits (etha-
nol with approximately 4%
methanol) by nucleation
with seeds of form II, main-
taining crystallization at a
low temperature of 0 oC and polymorphs
Figure 5. Two polymorphs
collecting the crystals within solution: alpha-glycine (sh
one hour after nucleation glycine (n
began. The typical yield
achieved was less than 30%,
but they proposed that when the process was optimized, a
commercial application was possible. By having better con-
trol over the crystallization process, they managed to crystal-
lize only the orthorhombic polymorph and to have the de-
sired crystal shape.
Ostwald noted in his Rule of Stages describing phase tran-
sitions that it is not the most thermodynamically stable state
that will normally appear first but that which is the closest, in
122


ofgl
aped
eedl


free energy, to the current state.1 3""3 In accordance with this
rule, crystallization of a compound having two polymorphs
will often proceed first with the growth of the metastable form
until the solution composition achieves the equilibrium solu-
bility of this form. When the saturation concentration of the
metastable form is reached it will stop growing. The stable
form may have nucleated at any point, determined by rela-
tive kinetics, up to and including when the saturation of the
metastable form is reached. The stable form will then grow,
thus causing the solution to be undersaturated with respect to
the metastable form, causing it to begin to dissolve. Once the
metastable form has completely dissolved at the expense of
the growing stable form, the stable form will grow until the
solution reaches its equilibrium solubility with respect to the
stable form.3'21 For example, a snapshot of the polymorphic
transformation of glycine crystallized from a water/ethanol
mixture is shown in Figure 5. At the beginning of the crystal-
lization, beta-glycine (needle) crystals form first. This is the
less stable polymorph. After 10
minutes, the more stable poly-
morph, alpha-glycine (shaped as
a coffin), grows at the expense
of the beta-glycine, which dis-
solves.
A more complete understanding
of solution-mediated polymor-
phism will involve appropriate
integration of nucleation, growth,
and dissolution, with the thermo-
dynamic equilibrium phase dia-
gram for the polymorphs.13i]

Crystallizer Design
Crystallization processes are
designed to achieve specific ma-
terial properties in the final solid
product, which are normally de-
termined by the crystal purity,
ycine in water-ethanol polymorph, mean particle size,
as a coffin) and beta- size distribution, and crystal
es). 1'3 habit. The design decisions that
influence these material charac-
teristics include: choice of sol-
vent, tailor-made surface-active modifiers,'1-71 fines removal
system, and the temperature and supersaturation fields in-
side the crystallizer (which are determined by the solute feed
concentration and temperature, crystallizer temperature, ves-
sel volume and geometry, agitation rate, and/or antisolvent
feed rate or evaporation rate, as appropriate). Buildup of im-
purities in the recycle streams also has the potential to sig-
nificantly influence crystalline material properties.
Chemical Engineering Education










The Next Millennium in ChE


Considering the fundamentals of crystallization, it is tempt-
ing to envision crystals growing quietly in a uniform me-
dium. This is an ideal seldom if ever realized in industrial
crystallization. In most industrial crystallization processes,
crystals grow suspended with myriad similar crystals in large,
vigorously agitated vessels. Frequently, the solution compo-
sition in the vessel is nonuniform both temporally and spa-
tially. Growing crystals are subject to collisions with other
crystals, the vessel agitator, wall, and internals. These phe-
nomena have a significant, sometimes profound, effect on
the properties of the resulting crystals. Crystallizer and crys-
tallization process design attempt to reconcile and man-
age these competing effects to produce adequate, even
superior crystals.
Modeling crystallizer flows is critically important and pre-
sents many difficulties, such as concentrated two-phase flows,
turbulent flow, complicated geometries, and a particle phase
that is changing in concentration and properties over time.
Despite these challenges, advances in closure modeling, nu-
merical solution techniques, and computational power are
beginning to make computational fluid dynamics (CFD) a
useful tool for characterizing crystallizer flows. Advances
have also been made incorporating the effect of the suspended
particles on the flow field.
Currently, there is great hope for Lattice Boltzmann tech-
niques to simplify the computational treatment of the equa-
tions of motion, making numerical solution much more effi-
cient. The techniques are also amenable to including the ef-
fect of solidsi'38 and are becoming commonly used. Because
they are so much more efficient than traditional solution tech-
niques, significantly more complicated and consequently
more realistic problems can now be solved. It remains a chal-
lenge to incorporate changing particle size distribution (PSD)
into these models, but this is an area of current research and
progress is being made.'39
The ultimate goal is to combine transport and population
balance modeling. Only then will realistic PSD predictions
be possible for a wide variety of nonideal systems. Progress
has been made, but a model applicable to a wide variety of
conditions remains elusive.

SYSTEMS DESIGN / PROCESS SYNTHESIS
Normally, large amounts of dissolved solute remain in so-
lution in the effluent stream of a continuous crystallizer, or at
the end of a batch crystallization. In either case, the crystals
are separated from the solution, and the liquor is recycled.
The crystallizer, therefore, is part of a larger flowsheet, which
may involve reactors, dissolvers, additional crystallizations,
various kinds of separators, heaters and coolers, etc. Both the
structure of the flowsheet and the devices and their operating
Spring 2006


Considering the fundamentals of

crystallization, it is tempting to

envision crystals growing quietly in

a uniform medium. This is an ideal

seldom if ever realized

in industrial crystallization.



policies influence the recycle flow rate and composition,
which in turn influence the performance of the crystallizer.
Surface active impurities and their buildup in recycle loops
can have a major impact (often adverse) on crystallizer
performance.
In recent years geometric methods have proven to be use-
ful for the systematic generation of process flowsheets. One
such tool, the crystallization path map, is useful for finding
feasible flowsheets in which crystallization steps occur. These
maps are closely related to residue curve maps for the syn-
thesis of azeotropic distillation systems.'40' The crystalliza-
tion paths are trajectories of the liquid composition in a crystal-
lizer as the solid is formed and removed from solution.!4 421
The presence of eutectics and compounds causes the pres-
ence of crystallization boundaries, which divide the map into
distinct crystallization regions. These regions are
nonoverlapping and mutually exclusive; that is, a liquid tra-
jectory that starts in one region cannot cross a boundary (ex-
cept by noncrystallization means) into an adjacent region.
Within each region there is one and only one crystal product,
which may be a pure component, a eutectic, or a compound.
Crystallization maps are useful for synthesizing flowsheets
for adductive crystallization (where a compound is the de-
sired crystal product), extractive crystallization, and many
other embodiments.'43-41 Although these maps are valuable
for laying out process flowsheets, the accumulation of impu-
rities associated with process recycle and the effect on crys-
tal properties both remain difficult to predict. Therefore, in-
tegrated pilot-scale testing including all recycle streams is
still required for confident system design, but there are sig-
nificant modeling opportunities here that will enable more
reliable and rapid development of process flowsheets.

SUMMARY AND CONCLUSIONS
During the last decade there have been significant advances
made in every aspect of crystal engineering. New experimen-
tal techniques, such as atomic force microscopy, allow us to
123












The Next Millennium in ChE


explore crystal surfaces and embryonic nuclei to learn about
their formation and growth, infrared and Raman spectros-
copy allow us to follow supersaturation changes and poly-
morphic transformations in situ while crystallization is tak-
ing place. New models have been developed to predict the
influence of both internal and external factors on crystal poly-
morph and shape. Molecular templates are being developed
to control crystal form and structure. Advances in fluid me-
chanics and transport phenomena have added greatly to our
understanding of mixing patterns and particle trajectories in-
side crystallizer vessels of realistic geometry. These and other
advances not mentioned or not yet even anticipated, are ex-
pected to continue.
Most of these advances are not being made by chemical
engineers, however. And moreover, they are taking place in
isolation. There is a large disconnect, for example, between
the microscopic models for growth of individual crystal faces
and the macroscopic models for CFD and PSD prediction.
Perhaps the larger question is, "How do we incorporate our
rapidly advancing knowledge and modeling capability to
make better products?"
There are major opportunities here for chemical engineers
who must be encouraged to take up the challenge. Specific
recommendations for incorporating crystal engineering into
chemical engineering research and undergraduate education
include:
Education
(1) Crystalline solids should be one of the core themes
throughout the chemical engineering curriculum.
Topics include: Thermodynamics course- thermody-
namics of solid-liquid phase diagrams and solubility
curves, spinodal curve and metastable zone curve,
traditional nucleation theory. Transport course-
diffusion of solute through a solution to a growing
crystal surface, estimates of characteristic times for
bulk diffusion, surface diffusion and integration of
solute at kink sites on a crystal surface, models for
flow of steps across crystal surfaces. Reaction
Engineering course- simultaneous reaction and
crystallization (i.e., precipitation). Separation course-
design of batch and continuous crystallizers. Design
course- simultaneous product and process design for
crystalline products (e.g., a dye, a pigment, or a
simple pharmaceutical such as paracetamol-trade
name Tylenol).

(2) Solid state chemistry should be part of the under-
graduate chemistry sequence. Topics include: crystal
structure and crystallography, nucleation (both
traditional and statistical mechanics models), solid
state bonding and bond chains, and surface growth
models-especially the spiral dislocation model.


There are numerous useful monographs and textbooks avail-
able on the subject of crystallization that may be used for
teaching undergraduates. These include: Randolph and
Larson,t461 Mullin,1471 and Davey and Garside.14s' The last of
these is short, inexpensive, and extremely well written. Un-
dergraduates should be happy to purchase this book.
Research Topics

(3) New models and experiments for understanding,
directing, and controlling nucleation and polymorph
selection
(4) Models for understanding and predicting polymorphic
phase transitions-both solution mediated and solid
state transformations
(5) Models and experiments for predicting the effect of
additives and impurities on crystal properties (e.g.,
crystal shape, size, polymorph)
(6) Improved models for CFD of dense suspensions of
crystals that are growing inside a solution crystallizer
(7) Improved procedures for simultaneous product and
process design for crystalline particulate products;
application and testing of the procedures in such
product sectors as: chiral and pharmaceutical
products, home and personal care (e.g., skin creams,
suntan lotions), food (e.g., margarine, chocolate, ice
cream), dyes and pigments, bulk chemicals (e.g.,
adipic acid), and specialty chemicals

ACKNOWLEDGMENT
I would like to acknowledge helpful discussions with Dr.
Daniel Green of the DuPont Company who influenced my
thinking about this subject, particularly in the area of CFD
modeling.

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Pilot Plant and Beyond," Current Opinion in Drug Disc. & Develop-
ment, 3 6. 723 (2000)
7. Gordon, R.E., and S.I. Amin, "Crystallization of Ibuprofen," U.S.
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Wiley, New York (1989)
10. Gavezzotti, A. "Crystal Symmetry and Molecular Recognition." Chap-
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Solid State, A. Gavezzotti, ed.. John Wiley, New York (1997)
11. Yau, S.-T., and P.G. Vekilov, "Quasi-Planar Nucleus Structure inApo-
ferritin Crystallization," Nature, 406 494 (2000)
12. Yau, S.-T., and P.G. Vekilov, "Direct Observation of Nucleus Struc-
ture and Nucleation Pathways in Apoferritin Crystallization." J. Am.
Chem. Soc., 123 1080 (2001)
13. Lefebvre, A.A.. J.H. Lee, N.P. Balsara, and C. Vaidyanathan, J. Chem.
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14. Burton, W.K.. N. Cabrera, and FC. Frank. "The Growth of Crystals
and the Equilibrium Structure of Their Surfaces." Phil. Trans. Roy.
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15. Geil, P., Polymer Single Crystals. Interscience (1963)
16. Land, T.A., A.J. Malkin, Y.G. Kutznesov. A. McPherson, and J.J. De
Yoreo. J. Crystal Growth, 166 893 (1996)
17. Paloczi, G.T., B.L. Smith, P.K. Hansma, D.A. Walters, and
M.A.Wendman, "Rapid Imaging of Calcite Crystal Growth Using
Atomic Force Microscopy with Small Cantilevers." Applied Physics
Letters. 73 1658 (1998)
18. Chen, K.. and P.G. Vekilov. "Evidence for the Surface-Diffusion
Mechanism of Solution Crystallization from Molecular-Level Obser-
vations with Ferritin," Phys. Rev. E. 66 021606 (2002)
19. Kittel, C., and H. Kroemer, Thermal Physics, W.H. Freeman. New
York (1980)
20. Herring. C.. "The Use of Classical Macroscopic Concepts in Surface
Energy Problems," in Structure and Properties of Solid Surfaces, R.
Gomer and C.S. Smith, eds., University of Chicago Press, Chicago
(1953)
21. Cherov, A.A., "The Kinetics of the Growth Forms of Crystals," Sov.
Phys. Cryst., 7728 (1963)
22. Cahn, J.W., J.E. Taylor, and C.A. Handwerker, "Evolving Crystal
Forms: Frank's Characteristics Revisited," Sir Charles Frank, OBE.
FRS, An Eightieth Birthday Tribute. R.G. Chambers, J.E. Enderby and
A. Keller, eds., Hilger, New York (1991)
23. Liu, X.Y., E.S. Boek, W.J. Briels, and P. Bennema, "Prediction of Crys-
tal Growth Morphology Based on Structural Analysis of the Solid-
Fluid Interface." Nature, 374 342 (1995)
24. Winn, D., and M.F. Doherty, "A New Technique for Predicting the
Shape of Solution-Grown Organic Crystals," AIChEJ. 44 2501 (1998)
25. Winn, D.. and M.F. Doherty, "Modeling Crystal Shapes of Organic
Materials Grown from Solution," AIChEJ. 46 1348 (2000)
26. Bisker-Leib, V., and M.F. Doherty, "Modeling Crystal Shape of Polar
Organic Materials: Applications to Amino Acids," Crystal Growth &
Design. 3 221 (2003)
27. Boek, E.S., D. Feil, W.L. Briels, and P.J. Bennema, Cryst. Growth,
114 389-410(1991)


28. Bernstein, J., Polymorphism in Molecular Crystals, Oxford Univer-
sity Press, Oxford, UK (2002)
29. Nichols. G., and C.S. Frampton, "Physicochemical Characterization
of the Orthorhombic Polymorph of Paracetamol Crystallized from So-
lution." J. Pharmaceutical Sciences, 87 684 (1998)
30. Ostwald. W.F., "Studien uber Die Bilding und Umwandlung fester
Korper (Studies on the Formation and Transformation of Solid mate-
rials)." Z. Phys. Chem.. 22 289 (1897)
31. Grant. D.J.W., "Theory and Origin of Polymorphism," in Polymor-
phism in Pharmaceutical Solids, H.G. Brittain, ed., Vol. 95 of Drugs
and the Pharmaceutical Sciences, Marcel Dekker, New York (1997)
32. Cardew, PT., and R.J. Davey, "The Kinetics of Solvent-Mediated Phase
Transformations," Proc. R. Soc., A398 415 (1985)
33. Ferrari, E.S., R.J. Davey, W.I. Cross, A.L. Gillon, and C.S. Towler,
"Crystallization in Polymorphic Systems. The Solution-Mediated
Transformation of Beta to Alpha Glycine," Crystal Growth and De-
sign. (3) 53 (2003)
34. Garcia, E., C. Hoff, and S. Veesler, "Dissolution and Phase Transition
of Pharmaceutical Compounds," J. Crystal Growth, 237-239, 2233
(2002)
35. Michaels, A.S., and A.R. Colville, "The Effect of Surface Active Agents
on Crystal Growth Rate and Crystal Habit," J. Phys. Chem., 64 13
(1960)
36. Klug, D., and J.H. Van Mil. "Adipic Acid Purification," U.S. Patent
Number 5,296, 639(1994)
37. Weissbuch, I., L. Addadi, L. Lahav, and L. Leiserowitz, "Molecular
Recognition at Crystal Interfaces," Science. 253 637 (1991)
38. Seta. T., K. Kono, and S. Chen, "Lattice Boltzmann Method for Two
Phase Flow," Int. J. Modern Phys. B. 17 169 (2003)
39. Brown, D.B.. S.G. Rubin, and P. Biswas. "Development and Demon-
stration of a Two/Three Dimensional Coupled Flow and Aerosol
Model," Proceedings of the 13th AIAA Applied Aerodynamics Confer-
ence, American Institute of Aeronautics and Astronautics (1995)
40. Doherty, M.F., and M.F. Malone, Conceptual Design of Distillation
Systems, McGraw-Hill, New York (2001)
41. Ricci, J.E., The Phase Rule and Heterogeneous Equilibrium, D. Van
Nostrand Co., New York (1951)
42. Slaughter, D.W.. and M.E Doherty, "Calculation of Solid-Liquid Equi-
librium and Crystallization Paths for Melt Crystallization Processes,"
Chem. Engng Sci., 50 1679 (1995)
43. Rajagopal, S., K.M. Ng, and J.M. Douglas, "Design and Economic
Trade-Offs of Extractive Crystallization Processes," AIChE Journal,
37437(1991)
44. Wibowo, C.. L. O'Young, and K.M. Ng, "Streamlining Crystalliza-
tion Process Design," CEP. 100, 1 30 (2004)
45. Lashanizadegan, A., D.T.M. Newsham, and N.S. Tavare, "Separation
of Chlorobenzoic Acids by Dissociation Extractive Crystallization,"
Chem. Engng Sci., 56 2335 (2001)
46. Randolph, A.D., and M.A. Larson, Theory of Particulate Processes,
Academic Press, San Diego (1988)
47. Mullin, J.W., Crystallization, Butterworth-Heinemann, Oxford, UK
(1993)
48. Davey, R.J., and J. Garside, From Molecules to Crystallizers, Oxford
University Press, Oxford, UK (2000) 1


Spring 2006











The Next Millennium in ChE


INSIDE THE CELL

A New Paradigm for Unit Operations

and Unit Processes?







JEROME S. SCHULTZ
University of California Riverside, California


Traditionally the chemical engineering paradigm for de-
signing industrial plants has been to separately con-
sider unit operations and unit processes. Although
these terms are not prevalent in current curricula, courses in
separations, reaction engineering, polymer engineering, etc.,
reflect this traditional view.
The usual scheme of process development starts at the labo-
ratory bench. And with experimentation and exploration, con-
ditions are optimized and then the process goes through a
scale-up procedure to reach commercial production needs.
Recent advances in MEMS technologies, however, have led
to the implementation of Lab-On-a-Chip devices such as the
integrated DNA analysis chip developed by Bums, et al.'"
(see Figure 1). These analytical devices bring together vari-
ous elements of unit processes such as separation steps, reac-
tion steps, and process control (detection and sensing proce-
dures). The capability for miniaturization and integration has
led some chemical engineers (e.g., Klavs Jensen) to envision
an entirely new paradigm for production methods, i.e., scaling
down instead of scaling up. Figure 2 from Professor Jensen's
Web site succinctly illustrates this contrast in paradigms.
Given the immense efforts in MEMS and nanotechnology
toward miniaturization and integration, one can readily specu-
late about potential future methods for carrying out chemical
processes through the application of these technologies. The


organizational structure of biological cells could have im-
portant lessons and impact in this regard. As the extensive
structural and operational characteristics of the biological cell
are being revealed, it is becoming clear that biological sys-
tems have evolved with a much more integrated design para-
digm of processes and operations than the traditional chemi-
cal engineering approach.


Jerome Schultz received his B.S. and M.S in chemical engineer-
ing from Columbia University, and his Ph.D. in biochemistry from
the University of Wisconsin in 1958. He started his career in the
pharmaceutical industry (Lederle Laboratories) then joined the
University of Michigan, where he was chairman of the Department
of Chemical Engineering. He spent two years at the National Sci-
ence Foundation as deputy director of the Engineering Centers
Program. In 1987 he joined the University of Pittsburgh as director
of the Center for Biotechnology and Bioengineering, and was the
founding chairman of the Department of Bioengineering-a nation-
ally ranked degree program in bioengineering. He recently spent a
year at NASA's Ames Research Center as a senior scientist in their
Fundamental Biology Program. In 2004 Dr. Schultz joined the fac-
ulty at the UC Riverside as the director of the newly formed Bioengi-
neering Program and the Center for Bioengineering.
He is a member of the National Academy of Engineering, a Fel-
low of the American Association for the Advancement of Sci-
ences, Editor of Biotechnology Progress, and was a founding
Fellow and President of the American Institute for Medical and
Biological Engineering.


Copyright ChE Division of ASEE 2006
Chemical Engineering Education











The Next Millennium in ChE


New advances in genomics, proteomics, metabolomics, cell
signaling, and control have allowed the documentation of the
thousands of species and interactions that comprise the inter-
nal milieu of cells. This vast amount of information has al-
lowed the harnessing of biological cells for many purposes
such as preparation of many biologics (e.g., insulin and EPO
[erythropoietin, monoclonal antibodies]), as well as the use


SAMPLE DROP MN THERMAL GEL GEL
LOADING METERNG MIXING REACTION LOADING ELECTROPHORESIS
L---i r "-i ,- R- -




S-- m-- ^< UID ENTRY D ET E I RUNNING BUFFER
5mm PORTS PHOTOOTECTORS PORTS

Figure 1. An example of a Lab-On-a-Chip device. This is
a DNA analysis system devised by Mark Burns and
associates.1'1 Various "unit operations" including meter-
ing, mixing, reactions, separations, and detection are
combined in a single device.


Microchemical Systems Scale Down and Out


Figure 2. Klavs Jensen's concept for a new paradigm
in chemical process development that utilizes the
multiplexing capabilities of MEMS technology to carry
out integrated synthesis and separation operations
in the same unit.


of cells for detoxification of herbicides.
Much of our thinking related to the future of biotechnol-
ogy is based on our appreciation of biological systems de-
duced from the dissection and separation of the components
of cells such as enzymes, signaling proteins, antibodies, RNA,
and DNA. Much of the richness of biological systems, how-
ever, resides in the structural features of cells. To date, many
of the structural elements that have been deduced from elec-
tron micrographs are categorized as organelles. Some of the
classes of organelles that have been identified include the
nucleus, mitochondria, lysosomes, peroxisomes, vesicles,
chloroplasts, and golgi (Figure 3). It is clear that cells are not
a bag of enzymes and substrates, i.e., a CSTR.
Although the morphology of these structural elements is
fairly well characterized by electron microscopic methods,
the functional and dynamic biological/chemical processes that
are taking place in these structures are not well understood at
all. Early hints from the study of some of these organelles
have revealed that biology does not separate unit processes
from unit operations, but rather integrates them. For example,
in chloroplasts the capture of photons and fixation of carbon
dioxide into carbohydrates simultaneously results in photoly-
sis-the separation of protons and oxygen evolution. Ribo-
somes integrate the genetic code and protein synthesis.
Most organelles are known to be complex multi-membra-
nous structures, but the composition and detailed organiza-
tion of these units are not known. One reason for the lack of
detailed understanding is that the typical dimensions of these
structures is on the order of nanometers and thus below the
resolution of optical microscopes. So they cannot be visual-
ized in detail while in a normal functional mode. This lack of


Figure 3. Diagramatic illustration of the various struc-
tures within a cell illustrating the complex structures
inside of cells that are responsible for much of the
biosynthetic activities of living systems.


Spring 2006


Not to scale







































Figure 4. Operational characteristics of near field microscopy (left). Close-up of the optical scanning probe (right). This is
one of the devices that will allow the visualization of structures within living cells and their behavior.


Ex=395 nm


Em=527 nm


+Glucose

-Glucose


GFPuv






(b)


Ex=395 nm


Em=527 nm


GFPuv


I YP Thr-Ser- GBP Gly-Thr-I GFP

Figure 5. Glucose-responsive protein engineered from a glucose
binding protein from E. coli, and two different green fluorescent
proteins. This type of structure can be introduced into a cell via a
plasmid to result in the biosynthesis of the sensor protein within
the cell. (a) In the absence of glucose the two fluorophores are in
close proximity and exhibit fluorescent energy transfer (FRET)
(left). In the presence of glucose the protein opens, and FRET is
reduced. (b) Structure of the fusion protein.110l


knowledge has hampered our ability to mimic these biologi-
cal systems for chemical processes.
Hope is on the way, however. To deal with this issue, indi-
rect methods are under active development to elucidate
mechanisms of the functioning of organelles.


Figure 6. Confocal image of a yeast cell containing
a maltose responsive protein similar to that
illustrated in Figure 5. The intensity of fluores-
cence is indicative of the concentration of maltose
in various regions of the cell. By incorporating
various indicator proteins of this type within cells,
one could monitor the dynamics of biosynthesis of
specific biomolecules in space and time. Vis a
vacule. (Bar = 1 micron). "'1


Many new instrumental techniques are being developed to
provide some real-time measurements of the behavior of sub-
cellular structures. These techniques include confocal micros-
copy,[2] two-photon microscopy,1 3 and optical coherence to-
mography.[41 Near field microscopy,151 Figure 4, allows the


Chemical Engineering Education


Incident light
X=500 nm


Light wavelength (X) 500 nm
Probe:
aperture size (a) 25-100 nm
evanescent field ain
tip-sample gap 5-50 inm
Sample:
feature size <
skin depth 0- co
Optics:
Far-field detector 1-100 mm
Interference effects )/4


The Next Millennium in ChE











( The Next Millennium in ChE

a) visualization of structural elements near the surface of the
I cell. Basically an optical fiber is drawn down to diameters
less than the wavelength of light and placed in contact with
the cell's outer membrane. The probe is scanned across the
(a) cell membrane to provide a map of structures just beneath
the membrane surface.
Several clever concepts based on various reporter tech-
niques have also been described recently that are beginning
to give specific dynamic data on intracellular events. The rap-
(b) idly expanding knowledge base on the structure and proper-
ties of green fluorescent proteins has opened up many oppor-
itunities for the protein engineering of intracellular probes. A
multitude of techniques is available for incorporating plas-
mids for these proteins into cells. These reporter indicators
(C) can be either freely mobile within the cell or localized in spe-
cific structures.6 71
Roger Tsien and his group'8 9] have pioneered the use of
6oO mo 1000 14o 1600 o) green fluorescent proteins as functional probes for
Raman Shift (cm ')
(S) biomolecules within cells based on the technique of fluores-
0.22 cence energy transfer (FRET). One recent application of this
0.20- approach has been to monitor sugar concentrations within
0.18- cells. Wel'l engineered a fusion protein consisting of a glu-
0.16- cose-binding protein and two different green fluorescent pro-
0 0.14- teins as shown in Figure 5. The sugar-binding moiety under-
0.12- goes a conformational change when glucose binds, such that
S0 10 it changes the distance between the GFP and YFP in a man-
0.08- ner that results in a change in FRET. Fehr, et al.,"" incorpo-
0.06- rated a similar maltose-binding protein into yeast cells. Us-
0.04 ing confocal microscopy, they were able to monitor the dis-
0.02- tribution of maltose throughout the cell, Figure 6.
0.00oo- Other techniques for monitoring the concentration of ma-
45 50 55 60 65 70 75 80 85 trials within cells are based on inserting tiny "biosensor"
pH Bulk Solution particles within cells. Raoul Kopelman and colleaguesE"12 have
( designed various materials called "PEBBLES" for measur-
ing oxygen, sugars, and pH within cells by optical techniques.
Talley, et al.,[13] have extended this approach by inserting
functionalized gold particles within cells that showed changes
in the Raman spectrum with local pH changes. Again, these
particles could be placed within cells to measure the distri-
bution in acidity within cells, Figure 7. In order to measure


Figure 7. Use of particles placed within cells to monitor
intracellular analyte concentrations by surface-enhanced
Raman spectroscopy. In this example of intracellular
monitoring, a compound that shows different Raman
spectra in its two ionic forms, is used to monitor the pH
distribution within cells."J' (a) Structure of the probe
particle and Raman spectra at different pH's. (b) The pH
behavior of Raman spectra. (c) Distribution of
nanoparticles within cells.

Spring 2006 129











The Next Millennium in ChE


local enzyme activity within cells, Weissleder, et al.,'14] in-
corporated a probe polymer with an enzyme hydrolysable
link between two fluorophores (see Figure 8).
With the increased amount of information afforded by these
imaging techniques, software to manage and display this data
in a meaningful fashion has become important. Several groups
are developing appropriate software for this purpose.15-1'
Government agencies are targeting technologies for im-
provement in intracellular imaging sensitivity. For example,
the NIH recently funded nine centers to develop cellular im-
aging techniques. Descriptions of these research efforts as
reported on the NIH Web site ( cellularimaging/index.html>) are quoted below.

OVERVIEW
The Exploratory Centers for the Development of High
Resolution Probes for Cellular Imaging support multi-
investigator teams to develop new technologies that enable
higher-sensitivity biological imaging in living cells. Each of
the nine centers willfocus on different strategies for probe
development, cellular delivery, probe targeting, and signal
detection to improve detection schemes by a factor of 10 to
100. A major emphasis of this initiative is to apply novel,
high-risk approaches to create fundamentally new probes
with enhanced spectral characteristics. The ultimate goal is
to develop probes and imaging systems that can be used to
routinely achieve single-molecule sensitivity for imaging
dynamic processes in living cells.
The centers are funded in conjunction with the NIH
Roadmap for Medical Research as part of the "New
Pathways to Discovery," an effort to advance our knowl-
edge of biological systems by building a better toolbox for
medical research. This initiative originated in NIGMS and
was later adopted by the Roadmap. NIGMS currently
supports seven of the centers as Roadmap-affiliated grants.
Funding for all nine centers is expected to total approximately
$25 million over four years ($6.8 million the first year).
1. Fluorescent Probes for Multiplexed Intracellular
Imaging. Kevin Burgess, Ph.D., Principal Investiga-
tor, Texas A&M University
Researchers from Texas A&M University and the
University of Pennsylvania plan to create novel
probe sets composed of multiplexed "through-bond
energy transfer cassettes," using multiple, linked,
donor-acceptor dye pairs that are optimized for
cellular imaging. These probes, which efficiently
absorb light at one wavelength, emit amplified
fluorescent signals at different, resolvable wave
lengths close to the red-infrared region, far removed
from cellular autofluorescence. The dye cassettes
will be specifically adapted for tracking interactions


of proteins in cells, ultimately with single-molecule
detection.
2. Sub-nm Dendrimer-Metal Nanoclusters as
Ultrabright, Modular Targeted in vivo Single
Molecule Raman and Fluorescence Labels *
Robert M. Dickson, Ph.D., Principal Investigator,
Georgia Institute of Technology
Metal nanoclusters, composed of silver and gold
atoms stabilized on organic dendrimers, exhibit
strong, size-dependent emission throughout the
visible and near-infrared spectrum. The spectral
characteristics of these clusters-their small size
(< 1 nm) and short and highly radiative


A No signal Signal *




Target
interaction






I o -

PEG P6E
S HNI NH HN



H 0 H


MI NlHa NH

PEG PE n

Figure 8. Example of a polymer probe to determine
enzyme activity within a cell. In this case the purpose
was to monitor the activity of a proteolytic enzyme
within cells. A special polymer substrate was created
that contained the peptide bond that the enzyme
cleaves and fluorophores (indicated by the circles) that
self-quench when in close proximity. When the peptide
bond is cleaved by the enzyme of interest, the
fluorophores are separated and quenching is prevented.
Thus, monitoring the appearance of fluorescence gives a
measure of local enzyme activity. Upper panel: Sche-
matic of the concept. Lower Panel: Example structure of
the probe polymer to measure enzyme activity.[14'


Chemical Engineering Education


130












The Next Millennium in ChE


lifetimes-create signals that have the potential
to be several orders of magnitude higher than
conventional labels. Grantees from the Georgia
Institute of Technology and Emory University
plan to finctionalize the nanoclusters for
attachment to different biological targets and to
develop single molecule imaging methods to
facilitate detection of the signal inside cells.

3. Single-Molecule Fluorophores for Cellular
Imaging William E. Moerner, Ph.D., Principal
Investigator, Stanford University

A group from Stanford and Kent State University
plans to synthesize and characterize a new class of
highly emissive (dicyanodihydrofuran) fluorophores
that exhibit large increases in signal when bound to
rigid surfaces. The strategy for incorporating the
probes into cells will be based upon the genetically
encoded tetracysteine-biarsenical targeting system
and then tested for single molecule specificity and
detection in bacteria.

4. Bioaffinity Nanoparticle Probes for Molecular/
Cellular Imaging Shuming Nie, Ph.D., Principal
Investigator, Emory University and Georgia Tech

A collaborative group will develop a new class of
polymer-encapsulated bioconjugated luminescent
nanoparticles with enhanced optical properties,
cellular delivery, and targeting/binding functions for
real-time and multicolor imaging in living cells. The
focus will be on core-shell semiconductor quantum
dots because of their improved brightness, resistance
against photobleaching, and simultaneous
nulticolor excitation. The researchers will test the
probes and their ability to detect them in studies
aimed at finding the subcellilar locations of p53,
nuclear factor B, and androgen receptor in living
cells.

5. Probes for Quantitative Optical and Electron
Microscopy David W. Piston, Ph.D., Principal
Investigator; Vanderbilt University Medical Center

A group from Vanderbilt will develop new fluores-
cent probes in the visible and infrared spectral
regions based on three approaches: genetically
encoded proteins, lanthanide chelates, and
nanocrystals (quantum dots). Each approach will be
tested for imaging of a protein in the plasma
membrane as well as an intracellular target.
Subcellular resolution fluorescence imaging by
widefield, deconvolution, confocal, and multi-photon
excitation microscopy will be used to implement and
test the new detection schemes based on spectral
and time-gated resolution. To reach the highest
resolution, the researchers will determine the utility


and limitations of using the new probes for direct
detection by electron microscopy for correlative
imaging.

6. Imaging Single Proteins in vivo with Quantum
Dots Sanford Simon, Ph.D., Principal Investiga-
tor, Rockefeller University

Researchers from the Rockefeller University plan to
extend and optimize an in vivo trans-splicing and
expressed-protein ligation approach to ligate
quantum dot derivatives to cytosolic or integral
membrane proteins. Their strategy includes
development of a conditional protein trans-splicing
approach that will allow probes to he ligated to the
targetfollowing a designated functional interaction.
The cellular fate of "activated" proteins will thus be
monitored by a change in the signal emitted by the
probe. The team intends to use these tools to study
exocytosis and transport through nuclear pores.

7. Light-Activated Gene Expression in Single Cells *
Robert H. Singer; Ph.D., Principal Investigator,
Albert Einstein College of Medicine

Investigators from the Albert Einstein College of
Medicine will develop a photoactivatable gene that,
upon exposure to light, begins transcription of
visible nascent chains of RNA. The ecdysone
response element and a caged, photoactivatable
ecdysone gene into which an RNA reporter has been
inserted, will be used. Gene expression will be
initiated by uncaging the ecdysone in vivo by
conventional and two-photon microscopy. The
system will be engineered into cancer cells and then
imaged intravitallv in tumors. The dynamics of
single RNA molecule movements and distribution
will be monitored.

8. Library-Based Development of New Optical
Imaging Probes Alice Ting. Ph.D., Principal
Investigator, Massachusetts Institute of Technology

The investigators plan three parallel approaches to
generate small-molecule and genetically encoded
probes that can be targeted to specific RNA or
protein sequences inside living cells. In the first,
libraries offluorophores will by synthesized in a
combinatorial fashion and then screened for their
ability to label small peptide motifs or RNA
aptamers with high specificity. In the second
approach, the natural bacterial enzyme biotin
transferase will be re-engineered to catalyze
covalent labeling of fluorescent probes to peptides
inside cells. Third, a systematic approach using a

See Inside the Cell
continued on page 139


Spring 2006











] l curriculum


ENERGY CONSUMPTION

VS. ENERGY REQUIREMENT







L.T. FAN, TENGYAN ZHANG, AND JOHN R. SCHLUP
Kansas State University Manhattan, KS 66506-5102

Today, the phrase "energy consumption" is popularly
spoken and written.111 Nevertheless, caution should L. T. Fan is University Distinguished Professor,
Holds the Mark H. and Margaret H. Hulings Chair
Sbe exercised for its continued use, especially in the in engineering, and is director of the Institute of
instruction of not only thermodynamics but also various Systems Design and Optimization at Kansas
other co s in e, i g in cmicl State University. He served as department head
other courses in engineering, including those in chemical of chemical engineering between 1968 and
engineering. 1998. He received his B.S. from National Tai-
wan University, his M.S. from Kansas State Uni-
The first law of thermodynamics teaches that energy is al- versity, and his Ph.D. from West Virginia Uni-
ways conserved in an isolated (or closed) system; it is neither versity, all in chemical engineering, in addition
to an M.S. in mathematics from West Virginia
created nor destroyed by any process, system, or phenom- University.
enon.[2-5] In contrast, the available energy analysis, which is Tengyan Zhang is a research associate in
the combination of the first and second laws of thermody- the Department of Chemical Engineering at
Kansas State University. She received her
namics, indicates that in the real world the available energy B.S. and M.S. from Tianjin University, and her
is never conserved, even in an isolated (or closed) system. Ph.D. from Kansas State University, all in
chemical engineering, in addition to a B.S. in
Even though in ideal circumstances available energy is only system engineering from Tianjin University,
theoretically conserved, the reality is that it is incessantly con- and an M.S. in computer science from Kan-
sumed, or dissipated, by any process, system, or phenom- sas State University.
enon.[6151] John R. Schlup is
presently a pro-
This consumption of available energy-or exergy- is ac- fessor in the Department of Chemical Engi-
companied by an increase in entropy, signifying the dissipa- neering at Kansas State University He ob-
tained B.S. degrees in both chemistry and
tion of available energy (or exergy) to the surrounding envi- chemical engineering from Kansas State
ronments. The dissipation of this available energy (exergy) University and a Ph.D. degree in chemical en-
r it tti r i iit tgineering from the California Institute of Tech-
reduces its potential or availability to perform useful work. nology. His current research interests include
the application of chemical engineering prin-
Similar to enthalpy, exergy is a state property of any sys- the applicatio n of chemical e engineering prin-
tem. The enthalpy as well as exergy contents of materials are of new materials from biomass.


Copyright ChE Division of ASEE 2006


Chemical En gineering Education










measured relative to the dead state, i.e., the extended stan-
dard state. It is defined by the environmental temperature,
the environmental pressure, and the datum-level substances.
Any element is part of the corresponding datum-level substance,
which is defined as being thermodynamically stable, existing
in abundance, and containing no available energy.'8 16-19] The
environmental temperature and pressure, which vary accord-
ing to time and place, are usually adopted as the datum-
level temperature and pressure; despite this, they are of-
ten specified as 298 K and 1 atm, respectively, for conve-
nience and also to be consistent with the conventionally
defined standard state.

MASS, ENERGY, AND AVAILABLE ENERGY
BALANCES
A system in which a phenomenon or process of interest
occurs is thermodynamically defined or specified by its mass,
energy, and available energy balances.8" "I 13,19-21] The follow-
ing subsections outline these three balances for system A, or
simply "the system," having multiple input and output streams
under the steady-state, open-flow conditions depicted in Fig-
ure 1, on the basis of a unit time, i.e., the rate. Figure 1 exhib-
its an isolated overall system; besides system A, it encom-


passes work and heat sources and sinks, and the entire sur-
roundings, i.e., environments. It is postulated that, except en-
ergy (enthalpy) and available energy (exergy) of mass flow-
ing through system A, other forms of energy-such as poten-
tial energy and kinetic energy-are negligible. Thus, the
changes in the enthalpy and exergy are induced by the trans-
fer of energy (between system A and its surroundings or other
systems) as heat or work. For simplicity, the aforementioned
three balances will be written around system A by referring
to Figure 1 and with the notations given in the section on
nomenclature.
Mass Balance
By taking into account both convective and diffusional
flows, the mass balance around system A yields


XMi=lMe (1)
i e
In terms of the molar flow rate, the above expression can
be rewritten as


[ (Mw) nk ]i =wI(Mw)k nk
i k J e k 1


Figure 1. Schematic diagram of an
isolated overall system encompass-
ing a steady-state, open-flow system
(system A), a heat source at tem-
perature Tm (system Ml), a heat
sink at temperature Tm2 (system
M2), a work source (system Nl), a
work sink (system N2), and the
entire surroundings at the environ-
mental temperature of T and the
environmental pressure of Po. In the
text, entering streams B,, B .... are
designated by subscript i; and
exiting streams CG, C2,,..., L-the
last being the leaking stream
(leakage)-are designated by
subscript e; the useful and leaking
streams among the exiting streams
are differentiated by additional
subscripts u and 1, respectively.


Spring 2006


Surroundings
N1Ml (To Po)


o lIQ I|(W )I |Q










Energy Balance
The energy balance around system A yields


Y.f Pkk 1+[|w1,Q i|
[ i k i


= Pknk ]+[lW2 +IQ2]+[(W)0 +IQo]} (3)
e k e_

Even under steady-state flow conditions, some parts of the
system, such as the surface of a rotating shaft of any pump,
do the work against the surroundings, or continuously gener-
ate electric charges which are discharged to the surround-
ings. This leads to the work loss, (Wx ), which will be trans-
formed into thermal energy and be trans erred to the surround-
ings as heat. The term, 1Wx ), therefore, can be combined
with the heat loss, IQ0I, thereby constituting the total heat
loss to the surroundings, IQow ; thus,


Qowl= Qol+(wx)o
This renders it possible to rewrite Eq. (3) as



I YX Pknk]]+[W +IQiI]


= 1 5 knkk +[W2|+Q2|]+IQOw
e k ),


Note that the energy content of the isolated overall system
remains invariant regardless of whether the analysis for sys-
tem A is under steady-state or unsteady-state flow conditions.
Entropy Balance
The principle of the increase of entropy, which is a mani-


Figure 2. Schematic diagram of a
steady-state thermal mixing
system, where a stream of water at
373 K and latm entering the
system at the rate of 0.5 kg-s is
mixed adiabatically and
isobarically with another stream of
water at 273 K and 1 atm entering
the system at the rate of 0.5 kg s-';
the resultant stream of water exits
from the system at the rate of 1.0
kg-s-1 at 1 atm and 323 K, resulting
from the energy balance that yields
{(0.5x 1.0x 373 + 0.5x 1.OX 273)/
[(0.5 + 0.5)x 1.0]11.3 21'


festation of the second law of thermodynamics, states: "The
entropy of an isolated system increases or in the limit re-
mains constant."2, 16] Consequently,

dS
-( >0
dt iso
The above equation can be rewritten as121

(AS)iso>0 (5)
In this expression, subscript iso stands for the isolated sys-
tem. The overall system depicted in Figure 1 is one such sys-
tem as previously indicated: It encompasses system A and its
surroundings. It is often convenient to transform Eq. (5) into
an equality by introducing a nonnegative quantity, o, defin-
ing the rate of entropy creation in the isolated overall system;
this gives rise to

(AS)iso (6)
By considering all the quantities that lead to the change in
entropy, we obtain


(AS)io =

v Y , Q21 fv 1- 1 1Q I
={[ k2?knk 2e+ } 'kk I+--
e kT.k T.k

+ IQ (7)
To


As indicated in connection with the energy balance, IQow in
the above expression includes the work loss (wx)0 as well
as the heat loss IQo0 to the surroundings.

Available Energy Balance
Combining the energy balance, Eq. (4), and the entropy
creation, Eq. (7), gives rise to


Chemical Engineering Education


Surroundings
(To, Po)


Stream 1, Output
H~O, 373 K H~,O, 325 K


Stream 1,
H,O, 373 K


Stream 2
H,O, 273 K
-------


Mixer


Output
H,O, 325 K
--













{ i[ (-To)y ) nk +[iW+IQ,1- To ] (8)
i k -k Tm I


{ if (P- To)nk +[w,+IQ2 1-_ +Too


In light of the aforementioned definitions of p and y, term
( ToY) in the above equation has a connotation of the avail-
able energy of molar species, for which symbol E is coined;
it is defined as the partial molar exergy. Thus,
E=P-ToY (9)
Hence, Eq. (8) can be rewritten as



i Eknkk i +|Iw,-+ QI(1- T1 (10)
i k Tm.


=* y X Ek1nk]1 +IW2+IQ2 I- To )+Too
e k T. ,

The quantities in the brace on the left-hand side of Eq. (10)
have an implication of the total available energy input to sys-
tem A. Note that they are not equal to the quantities in the
brace on the right-hand side of Eq. (10) that have an implica-
tion of the total available energy exiting from the system.
Their difference, Too, signifies the available energy dissi-
pated by all types of irreversibility, which is transferred as
thermal energy or heat from the system to its surroundings
under the environmental conditions, as elaborated earlier.
The partial molar enthalpy relative to the dead state, P, in
Eq. (4), the partial molar entropy relative to the dead state,
y, in Eq. (7), and the partial molar exergy relative to the
dead state, e, in Eq. (10) can be estimated from the follow-
ing equations.'7 I. "17 3


TP
f=30+ pdT +v -T P


y=yo+ J CdT-iT(TT dP
To Po
TT T T aT P


E=r0+ Cp( 1-- ,dT+ i v-(T-T o -,)
To Po .P


Many of their values can also be found in various sources.'"
17.22.23]


THE MIXER EXAMPLE
This illustration is based on an extremely simple example.
It is well suited, however, for effectively conveying the main
theme of the current contribution. This example is an exten-
sion of the well-known onel" '-2 in which: no work or heat is
transferred from the system of concern to other systems and
vice versa; no work or heat is lost from the system to its sur-
roundings; no moving mechanical parts are visible on the
system; and no changes in the chemical compositions of the
streams passing through the system are detectable. Never-
theless, simply mixing two streams of water at different tem-
peratures internally leads to significant reduction of the avail-
able energy (exergy) of the system. Figure 2 illustrates the
system, which is a steady-state, thermal-mixing device, or
simply "the mixer."

Mass Balance

The term, XMe. in the mass balance equation, Eq. (1),
e.i
vanish for the mixer; thus,


Mi=Me.u or Me.u- Mi=0


Since M.u =1.0 kg-s-l and M ,=0.5+0.5= 1.0 kg-s-1, we
have i


Meu- M,=1.0-.00=0 kgs-1


As expected, the mass is conserved in the mixer and its
surroundings, collectively constituting the isolated overall
system: Water entering the mixer from its surroundings,

IM,
i
balances out exactly the water exiting from the mixer to its
surroundings, Me.u
Energy Balance

The terms, (PIn)e,d, (13n)i, W11, W21, IQ, IQ21, and
e.d e.l


Qo0w in the energy balance equation, Eq. (4), vanish when
applied to the mixer; thus,


(Pn)i=(3n)e,u or (Pn)e,u- (in)i=0 (16)
i i
On the basis of mass flow M, instead of molar flow n, the
terms in the above expression are evaluated as


Spring 2006











The first law of thermodynamics teaches that energy is always conserved
in an isolated (or closed) system; it is neither created nor destroyed by any process,
system, or phenomenon.12-5 In contrast, the available energy analysis, which is the
combination of the first and second laws of thermodynamics, indicates that
in the real world the available energy is never conserved ....


(PM)u =(25.0)(1.0)=25.0 kcal-sl-, in which


(P)eu=ao cpdt+ v-T [ dP
To Po P
=0+(50.0-25.0)(1.0)+0=25.0 kcal-kg-1

and similarly


X(PM)i =(-25.0)(0.5)+(75.0)(0.5)=25.0 kcal-s-'
1
Consequently,


(PM)e,u (PM)i =25.0-25.0=0 kcal-s-' (17)

Obviously, the energy in the mixer and its surroundings-
collectively constituting the isolated overall system-remains
unchanged; energy is conserved, i.e., never consumed. The
energy entering into the mixer from its surroundings with the
flow of water,
S(PM)i,
i
balances out the energy exiting from the mixer to its surround-
ings with the flow of water, (PM), Naturally, the first-law
efficiency of the mixer in terms of energy conservation is
(25.0/25.0) or 100.0%.

Entropy Balance
The terms,


(LkYknk J'Yknk Qi 2 ,
e,d k e,d el k Je, l m2


and IQow I/To in the expression for entropy creation, Eq. (7),
vanish when applied to the mixer and its surroundings, i.e.,
to the isolated overall system; thus,


On the basis of mass flow M, instead of molar flow n, the
terms in the right-hand side of the above expression are evalu-
ated as

(y M) =(0.080)(1.0)=0.08 kcal-s-l K-1
in which


(Y)eu=0 dT- T 0 T dP
(Y"eu 1-i J EdT J [Y- )
To Po

=0+1ln 323- 0=0.080 kcal.kg- K-1
S298 j


and similarly


(y M). =(-0.088)(0.5)+(0.224)(0.5)=0.068 kcal-s-1 K-1

As a result, we have

(AS).i =

=(Y M)eu -(Y M)i
i
=0.012 kcal-s-1 K-1
or, equivalently expressed as the most diffused form of ther-
mal energy under the environmental conditions,

To(AS)iso= ToG
=(298)(0.012)

=3.576 kcal-s- -K-1 (19)
This ascertains that the entropy change of the isolated over-
all system, accompanying whatever process or phenomenon
is occurring in the mixer, is destined to be nonnegative.

Available Energy Balance
The terms,


k IEkk knk k ,Wl, W2|, Qi(-To/Tml),
e,d k e.l k e.l


Chemical Engineering Education


(AS)iso = = (y n)e,u E( n)i
i










and IQ2I(1-To/Tm2), in the available energy balance equa-
tion, Eq. (10), vanish when applied to the mixer; thus,


X(En)i =(n)e.u+(Too) or (En)e.u (en)i=-(Too) (20)
i I
On the basis of mass flow M, instead of molar flow n, the
terms in the above expression are evaluated as

(eM) =(1.160))(1.0)= 1.160 kcal-s-

in which,

( e,u = e,.u-To(Y)e.
=(25.0)-(298)(0.088)= 1.160 kcal.kg-'

and similarly


X(eM)i =(1.224)(0.5)+(8.248)(0.5)=4.736 kcal-s-1

Hence,

(eM), (eM)i =1.160-4.736=-3.576kcal-s-1 =-(Too) (21)

Note that Eq. (21) is totally unlike Eqs. (15) and (17): Exergy
is not conserved. No work is performed on the surroundings
by water passing through the mixer and no heat is lost to the
surroundings from water passing through the mixer. In fact,
it is even assumed that the flow of water does not even en-
counter any friction during the passage through the mixer.
Nevertheless, the available energy (exergy) entering into the
mixer from its surroundings with the flow of water,


C(EM)i,

does not balance with the available energy (exergy) exiting
from the mixer to its surroundings with the flow of water,

(EM).u
In fact, it decreases, thereby correctly reflecting the irrevers-
ibility of the thermal mixing of two water streams inside the
mixer. The difference signifies the dissipation of available
energy, evaluated by Eq. (21) as -3.576 kcal-s-1: Available
energy (exergy) is always consumed, or dissipated, in the real
world. Naturally, this dissipation of available energy is the
only source of the entropy increase or creation in the isolated
overall system, whose thermal equivalent is evaluated by Eq.
(19) as +3.576 kcal-s- In essence, the energy of water
streams "available" to perform useful work is lost to its sur-
roundings in the most diffused form-thermal energy under
environmental conditions-which is totally unavailable to do
any work. This results in entropy creation in the isolated over-


all system, which can be the universe itself. In drastic con-
trast to the first-law efficiency, the second-law efficiency in
terms of available energy (exergy) conservation is merely
(1.160/4.7361) or 24.5%.
Now suppose that the mixer is externally heated at the rate,
IQ of 50 kcal-s-1 by a heater at the temperature, Ti1, of 800
K. Naturally, the temperature and the corresponding energy
(enthalpy) of water exiting from the mixer increase to 373 K
and [.0X(100-25)]X 1.0 kcal-s-l, i.e., 75kcal-s-l, respec-
tively. The energy balance around the mixer yields the first-
law efficiency of [75/(25+50)] 100% or 100%, thereby in-
dicating that it is not affected by external heating. The con-
comitant change in the available energy (exergy) of water
exiting from the mixer is from 1.160kcal-s-lto [75-(298
X0.224)] X 1.0 kcals-1, i.e., 8.248 kcal-s-'. This is obviously
an increase rather than a decrease without external heating,
thus indicating the possibility of enhancing the mixer's sec-
ond-law efficiency. In reality, however, the opposite is the
case: simply adding external heating reduces the second-law
efficiency from 24.5% to { 8.248/[4.736+50X (1-298/800)] } X
100%, i.e., 22.8%. Regarding the first law, Seider, et al.," 1
state, ". .. it can not even give a clue as to whether energy is
being used efficiently . ." Moreover, according to Reistad
and Gaggioli,'241 "The second-law efficiency is the perfor-
mance parameter which indicates the true thermodynamic
performance of the system."

CONCLUDING REMARKS
With the aid of a deceptively simple example, it has been
unequivocally demonstrated that energy is conserved, i.e.,
never consumed; what is always consumed, or dissipated, is
available energy (exergy), which is the essence of this brief
contribution. This simple example also succinctly indicates
that an attempt to rigorously assess the sustainability of any
process or system should be based firmly upon the thermo-
dynamics, in general, and the evaluation of the system's sec-
ond-law efficiency based on available energy (exergy), in par-
ticular, as practiced in the EU community'251 and the Canton
of Geneva in Switzerland.126

ACKNOWLEDGMENT
This work was supported by U.S. Department of Energy
under Contract DEFG36- 011D14126.

NOMENCLATURE
A system A
cp specific heat, J mol '. K`'
M mass flow rate including both convective and diffu-
sional flows, kg s'
Mw molecular weight, g mol'
N molar flow rate including both convective and diffu-


Spring 2006













sional flows, mol s-'
P pressure, atm
Q0o heat loss to the environment per unit time, J s-' or kcal -
s5

IQow total heat loss to the environment per unit time, J s-' or
kcal s-'
Qi heat transmitted from system MI to system A per unit
time, J s-' or kcal s

IQ1 heat transmitted from system A to system M2 per unit
time, J s-' or kcal s-'
S entropy, J K-

s partial molar entropy, J mol-' K-'
T temperature of system A, K
Tm, temperature of system Ml, K
T n temperature of system M2, K
v volume, m3

IWo0 work lost to the surroundings per unit time, J s-' or kcal
S-1

W l work supplied from system N1 to system A per unit
time, J s-' or kcal s '

IW2I work supplied from system N2 to system A per unit
time, J s-' or kcal s'

(Wx)0 work lost to the surroundings except that due to
expansion of the boundary of system A per unit time,
J s-' or kcal s-'
Greek letters

p partial molar enthalpy relative to the dead state, J mol' or
kcal kg-'

P, partial molar chemical enthalpy, J mol' or kcal kg-'

E partial molar exergy, J mol-' or kcal kg-'
Eo partial molar chemical exergy, J mol' or kcal kg

y partial molar entropy relative to the dead state, J mol-' k'
or kcal kg-'-K-

Yo partial molar chemical entropy, J mol- k' or kcal kg '.K-'

Co created entropy per unit time, J sec i' k- or kcal sec-.'K-'

Subscripts
0 dead state
e,u useful output streams
i input streams
iso isolated system
k material species
1 leakage

Superscript
0 standard state


REFERENCES
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Company (2005)
2. Denbigh, K.G., "The Second-Law Efficiency of Chemical Processes,"
Chem.Engr. Sci., 6, 1 (1956)
3. Gaggioli, R.A., "Principles of Thermodynamics," in Thermodynam-
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Gaggioli, American Chemical Society, Washington, D.C. (1980)
4. Kyle, B.G., Chemical and Process Thermodynamcs, Prentice Hall:
New Jersey (1999)
5. Stanley, I.S., Chemical and Engineering Thermodynamics, John Wiley
& Sons, Inc., 3rd Ed. (1999)
6. Keenan, J.H., "Availability and Irreversibility in Thermodynamics,"
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7. Hatsopoulos, G.N., and J.H. Keenan, Principles of General Thermo-
dynamics, Wiley, New York (1965)
8. Denbigh, K.G., The Principles of Chemical Equilibrium, Cambridge
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9. Szargut, J. and Petela, R., Egzergia, Warezawa, 1965 (in Polish)
10. Szargut, J., D.R. Morris, and FR. Steward, Exergy Analysis of Ther-
mal, Chemical, and Metallurgical Processes, Hemisphere Publishing
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11. Fan, L.T., J.H. Shieh, "Thermodynamically Based Analysis and Syn-
thesis of Chemical Process Systems," Energy, 5, 955 (1980)
12. Petit, P.J., R.A. Gaggioli, "Second Law Procedures for Evaluating Pro-
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ton, D.C. (1980)
13. Sussman, M.V., Availability (Exergy) Analysis A Self Instruction
Manual, Tufts University (1980)
14. Fan, L.T., J.H. Shieh, T. Ishimi, and T. Graham, "Practical Applica-
tions of Process Systems Engineering to Energy and Resource Con-
servation and Management," Comp. Chem. Eng., 7, 793 (1983)
15. Kenney, W.F., Energy Conservation in the Process Industries, Aca-
demic Press, Inc. (1984)
16. Keenan, J.H., Thermodynamics. Wiley, New York (1941)
17. Gaggioli, R.A., Thermodynamics and the Non-Equilibrium System,
Ph.D. Thesis, University of Wisconsin (1961)
18. Reistad, G.M., Availability: Concepts and Applications, Ph.D. Thesis,
University of Wisconsin (1970)
19. Debenedetti, PG., "The Thermodynamic Fundamentals of Exergy,"
Chem. Eng. Ed., XVIII, 116 (1984)
20. Paulus, D.M. and R.A. Gaggioli, "The Dead State According to the
Available Energy of Gibbs," American Society of Mechanical Engi-
neers, Advanced Energy Systems Division (Publication) AES, v 40
(2000)
21. Seider, W.D., J.D. Seader, and D.R. Lewin, Product and Process De-
sign Principles, John Wiley and Sons (2004)
22. Ishimi, T., J.H. Shieh and L.T. Fan, "Thermodynamic Analysis of a
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Soltes, ed., Academic Press, New York (1983)
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25. Lowex News, "Low Exergy Guidebook in 2004 Offers Basic Knowl-
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De Lausanne, Geneve-Mai (2005) (in French) O


Chemical Engineering Education












The Next Millennium in ChE


Inside the Cell
continued firo page 131


combination of rational design and screening of
mutant libraries will be used to create green
fluorescent proteins with improved photophysical
properties.

9. Genetically Targetable Labels for Light and EM *
Roger Y. Tsien, Ph.D., principal investigator,
University of California, San Diego

A team from the University of California and the
University ofIllinois plans a series of approaches to
generate fluorescent proteins with increased
photostability and higher quantum yield, to explore
quantum dot construction and targeting, and to
further develop tetracysteine labeling techniques for
light and electron microscopy. The team's plans also
include exploring genetically targetable labels with
long excited state lifetimes based on lanthanide and
transition metal luminescence as well as directed
evolution of fluorescent proteins to improve their
photophysical properties. A major goal of this team
is to enable direct visualization in the electron
microscope of the same molecules that have been
tagged, observed, and dynamically tracked in the
light microscope.

Now that breakthroughs are under way to provide specific
information on the functioning and control of organelles, a
unique opportunity is evolving for chemical engineers to use
this mechanistic information to design new integrated
biocellular operations and processes.

It is likely that exceptional progress will be made in the
next decade to reveal the physical chemical phenomena that
govern the organization and behavior of the biochemical pro-
cessing units within cells. Naturally then, new concepts of
process design will emerge for the chemical/biochemical in-
dustry through the research efforts of biochemical engineers.
As this knowledge becomes available it will be incorporated
into the graduate-program courses in chemical engineering
departments as an enhancement to courses such as systems
biology, bio-MEMS, biochemical separations, bioprocess
engineering, and pharmaceutical biotechnology. One can ex-
pect a dramatic evolution in process technology that will be-
come an important capability for future chemical engineers,
especially for high-value, low-volume products.


REFERENCES:
1. Bums, M.A., B.N. Johnson, S.N. Brahmasandra, K. Handique, J.R.
Webster, M. Krishnan. T.S. Sammarco, P.M. Man, D. Jones, D.
Heldsinger. C.H. Mastrangelo. and D.T. Burke, "An Integrated
Nanoliter DNA Analysis Device," Science (282) 484-487 (1998)
2. Yoshida, M., K. Tohda. and M. Gratzl, "Optical Detection in Micro-
scopic Domains 3:Confocal Analysis of Fluorescent Amphiphilic
Molecules." Anal. Chem. (75) 6133-6140 (2003)
3. Rubart, M., "Two-photon microscopy of cells and tissue," Circ. Res.
(95) 1154-66 (2004)
4. Reeves, A., R.L. Parsons, J.W. Hettinger, and J.I. Medford, "In vivo
three-dimensional imaging of plants with optical coherence micros-
copy," J. Microscopy (208) 177-189 (2002)
5. Wabuyele M.B., M. Culha, G.D. Griffin, P.M. Viallet, and T. Vo-Dinh,
"Near-field scanning optical microscopy for bioanalysis at nanometer
resolution," Methods Mol. Biol. (300) 437-52 (2005)
6. Jin. T., N. Zhang, Y. Long. C.A. Parent, and P.N. Devreote.;, "Local-
ization of the G Protein bg Complex in Living Cells During Chemot-
axis." Science (287) 1034 (2000)
7. Ilegems, E., H.M. Pick, C. Deluz, S. Kellenberger, and H. Vogel,
"Noninvasive Imaging of 5-HT3 Receptor Trafficking in Live Cells
From Biosynthesis To Endocytosis,"J. Biol. Chem. (279) 53346-53352
(2004)
8. Miyawaki, A., and R.Y. Tsien. "Monitoring protein conformations and
interactions by fluorescence resonance energy transfer between mu-
tants of green fluorescent protein." Methods Enzymol. (327) 472-500
(2000)
9. Zhang J.. R.E. Campbell. A.Y. Ting, and R.Y. Tsien, "Creating new
fluorescent probes for cell biology." Nature Review Mol. Cell Biol.,
(12) 906-18 Dec. 3 (2002)
10. Ye. K.. and J.S. Schultz, "Genetic engineering of an allosteric-based
glucose indicator protein for continuous glucose monitoring by fluo-
rescence resonance energy transfer." Anal. Chem. (75) 3451-3459
(2003)
11. Fehr. M., W.B. Frommer, and S. Lalonde, "Visualization of maltose
uptake in living yeast cells by fluorescent nanosensors," Proc. Natl.
Acad. Sci. USA (99) 9846-51 (2002)
12. Buck, S.M., Y.L. Koo. E. Park. H. Xu, M.A. Philbert, M.A. Brasuel,
R. Kopelman. "Optochemical nanosensor PEBBLEs: photonic explor-
ers for bioanalysis with biologically localized embedding," Current
Opinion in Chem. Biol. (8) 540-546 (2004)
13. Talley. C.E., L. Jusinski, C.W. Hollars. S.M. Lane, and T. Huser, "In-
tracellular pH Sensors Based on Surface-Enhanced Raman Scatter-
ing," Anal. Chem. (76) 7064-7068 (2004)
14. Weissleder. R.. C. Tung, U. Mahmood, and A. Bogdanov Jr., "In vivo
imaging of tumors with protease activated near-infrared fluorescent
probes." Nature Biotechnology (17) 375 (1999)
15. Eils, R., and C. Athale, "Computational imaging in cell biology," J.
Cell Biol. (161) 477 (2003)
16. Gerlich, D.. J. Mattes, and R. Eils, "Quantitative motion analysis and
visualization of cellular structures." Methods (29) 3-13 (2003)
17. Slepchenko. B.M.. J.C. Schaff. I. Macara, and L.M. Loew, "Quantita-
tive cell biology with the Virtual Cell," Trends in Cell Biol. (13) 570
(2003)
18. Rueden, C.. K.W. Eliceiri, and J.G. White, "VisBio: A Computational
Tool for Visualization of Multidimensional Biological Image Data,"
Traffic (5) 411-417 (2004) 0


Spring 2006










Class and home problems i


GAS PERMEATION COMPUTATIONS

WITH MATHEMATICS


HOUSAM BINOUS
National Institute of Applied Sciences and Technology 1080 Tunis, Tunisia


Gas separations using membranes have received
increased attention by the scientific and industrial
community. This technique is now at a mature stage
and can compete with more common techniques used in the
petrochemical industry such as cryogenic separation, gas ab-
sorption, and pressure swing adsorption. The nonporous mem-
branes can be organic or inorganic. They are classified ac-
cording to their thermal and chemical stability as well as their
selectivity to different gases. The mechanism of separation is
based on the differences in the dissolution and diffusion of
gases in the nonporous membrane. The separation of hydro-
gen from other gases such as carbon dioxide and carbon mon-
oxide in syngas plants is a very important industrial applica-
tion of this technique. Acid gas (CO, and H2S) elimination
from natural gas is another application of membrane separa-
tions. Very often one is confronted with the separation of
multicomponent mixtures. Thus, we consider a hypothetical
ternary mixture, in the first part of the paper, to show how
one can obtain the permeate and reject compositions as well
as the membrane area.


SEPARATION OF A TERNARY MIXTURE
A ternary feed mixture has the following composition and
flow rate:

XfA=0.25, xfB=0.55, xfC=0.2 and qf=1.0xl04 cm3 (STP)/s
Since the stage cut, defined as the fraction of the feed al-
lowed to permeate, is 0=0.25, the permeate flow rate, q is
equal to 0.25 x 10 cm3(STP)/s. The permeabilities, expressed
in cm3 (STP) cm/(s cm2 cmHg), of components A, B, and C


Housam Binous is a full-time faculty mem-
ber at the National Institute of Applied Sci-
ences and Technology in Tunis. He earned
a Diplome d'ingenieur in biotechnology from
the Ecole des Mines de Paris and a Ph.D.
in chemical engineering from the University
of California at Davis. His research inter-
ests include the applications of computers
in chemical engineering.
V^ '


Copyright ChE Division of ASEE 2006
Chemical Engineering Education


The object of this column is to enhance our readers' collections of interesting and novel prob-
lems in chemical engineering. Problems of the type that can be used to motivate the student by
presenting a particular principle in class, or in a new light, or that can be assigned as a novel
home problem, are requested, as well as those that are more traditional in nature and that eluci-
date difficult concepts. Manuscripts should not exceed 14 double-spaced pages and should be
accompanied by the originals of any figures or photographs. Please submit them to Professor
James O. Wilkes (e-mail: wilkes@umich.edu), Chemical Engineering Department, University
of Michigan, Ann Arbor, MI 48109-2136.
<__________________________________________










are equal to

PA=200x10-l, P' =50x10-10, and Pc=25 x10-0.
This mixture is to be separated by a membrane with a thick-
ness t=2.54x 10" cm. Pressures on the feed and permeate sides
are p,=300 cmHg and p,=30 cmHg. We will use the com-
plete-mixing model to compute the permeate and the reject
compositions as well as the membrane area. The three rate-
of-permeation equations are:

qpypi =- Am(phxoi-piypi) for i=1,2,3 (1)

The three material balances equations written for compo-
nents A, B, and C are:
1 0
xoi = xfi- ypi for i=1,2,3 (2)
1-0 1-0
Finally, we have an additional relation that is the summa-
tion rule for mole fractions:

1yPi=1 (3)
i=l
Equations 1 through 3 are labeled rate, matbalance, and
summation, respectively. We need to enter these equations in
the Mathematica notebook'21 and call FindRoot as follows:
FindRoot[ ratell, rate2, rate3,
matbalancel, matbalance2, matbalance3,
summationl, {yp,A 0.2}, {yp, 0.2}, {yp,
0.2}, {A,, 10o6}, {XoA, 0.2}, {XOB, 0.2}-
{xc, 0.2}]


qf Xf


qo xo
qp yp


(a) complete mixing model




0Oqf yp (1-O) qf xo
qf Xf -~

dAm

(c) countercurrent flow


FindRoot uses different root search techniques that can be
selected by the user. If one specifies only one starting value
of the unknown, FindRoot searches for a solution using New-
ton methods. If the user specifies two starting values, FindRoot
uses a variant of the secant method, which does not require
the computation of derivatives. All this is handled internally
by Mathematica, making the solution of complex systems of
nonlinear algebraic equations very easy. We get the follow-
ing solution for the permeate and reject compositions and the
membrane area labeled A:
{ypA- 0.455281, yp-> 0.450286,
Ypc 0.0944335,
A -3.54176X106, xOA, 0.181573,
xB- 0.583238, xoc0-- 0.235189}
which is in agreement with results using a tedious iterative
technique."]

ENRICHMENT OF AIR IN OXYGEN
USING MEMBRANE PERMEATION
In this section, we present the study of the enrichment of
oxygen in air using a single-stage membrane module. This
problem has been treated first by Walawender and Stern''
and later by Geankoplis.'" The binary mixture, A (oxygen)
and B (nitrogen), has an ideal separation factor, the ratio of
the permeabilities of the two species, a* =10. The perme-
ability of oxygen is PA=500x10-10 cm3 (STP) cm/(s cm2
cmHg). The membrane is more permeable to oxygen and has


Sqf yp



qf Xf q (1-) qf xo

dAm

(b) cross flow





0 qf yp
qf Xf (1-) qf xo

dAm
(d) co-current flow


Figure 1. Flow patterns.
Spring 2006










a thickness t=2.54X 10-3 cm. The stage cut, 0, is set equal to
0.2. The values of the pressures in the feed and permeate
sides chosen by Geankoplist" are p,=190 cmHg and p,=19
cmHg, which give a ratio of pressures, r, equal to 10. The
feed rate and composition are given by:
xfA=0.209, x,=0.791 and q,=1.0x 106 cm3 (STP)/s.
The different flow patterns, shown in Figure 1 (previous
page) and considered in this study, are complete mixing, cross-
flow, countercurrent flow, and co-current flow. Calculations
for each flow pattern will be presented in a separate sub-
section.
1. Complete-Mixing Case
The permeate mole fraction, yp, is the solution of the fol-
lowing quadratic equation:


o [xxo- P yp
Yp = Ph J (4)
1-yp ( -(xo)_ P, )(1-yp)


where the reject composition, xo, is given by the mass bal-
ance:

Xf -yp
xo= (5)
1-0

We also define a* and r by a* = PA/ PB and r=P/P.
The membrane area is then obtained using Equation (6):

Am Ofyp (6)
PA )PhX| Yp
A -/(phxo-plyp)

For our particular problem, we find the following results
using Mathematica:
yp=0.5067, x0=0.1346, and Ao1=3.228 108cm2.
These results are in agreement with those found by
Geankoplis."l'
2. Cross-Flow Case
The local permeate rates over a differential membrane area
are given by


-ydq= -(ph x y)dAm (7)



-(1-y)dq= (ph(1-x)-p,(1-y))dA (8)

In addition, we can derive Equation (9) from total and com-
ponent mass balances:


ydq=d(qx) (9)
These three governing equations are solved simultaneously
using the Mathematica built-in function called NDSolve. The
following boundary conditions are used:

qAm =0=qf, XAm=0 XfA and yAm=0YPi

where ypi is obtained by solving the quadratic equation


ypi Ph J

yp (I-xfA)-p- ypi)


The command used in the notebook to solve the system of
ODEs is:
myODEsoln[ f]
NDSolve [ {y[A] D [q[A] {A, 1}]==
D[Eq[A] x[Am], {Am, 1} ],
-y[Am] D[q[A], {A,1}]== P'A/t (Ph X[A]
Ply [A] ) ,
(1- y[A] ) D[q[Am], {Am, }]==
P',/t+(ph(l- X[A) p1(1- y[A])), x[0]
== xf,
y[0] == ypi,q[0] == q,, {x[Am]
y[A ],q[A] }, {Am, 0, n}]
We use FindRoot to get the total membrane area. In fact,
we must satisfy the following condition: 0=0.2 where the
stage cut, 0, is given by 6=(qf-qled)/qf.
The Mathematica command is written as follows:
qend[2Q_?NumericQ] : =Flatten[(q[AJ /.
myODEsoln[Q] )/.A -> ]
Aso = FindRoot [(qf- qend[ ] )/qf==0,
{(,2 10^8,3 10^8}, Maxlterations->1000];
The final result is a membrane area and a reject composi-
tion equal to: Aso=2.899x 108 cm2 and x0=0.1190. A compo-
nent balance, 0y +(1- 0)Xo=xfA, can be used to obtain the per-
meate mole fraction and we find that y =0.5688. Our approach
gives similar results as those given by Geankoplist' but is far
less tedious and more accurate. We can check our results by
integrating y(Am) forAm varying from 0 to A,.,, achieved with
the command:
Integrate [First [y [A] / .myODEsoln [ /
.Ao]] /. Am-area,
(area, 0, Q /.Ao}]/Q/.Aol
We get yp=0.5634, a value in agreement with the previous
result. Since numerical integration is used, the later value of


Chemical Engineering Education










yp is less exact. In Figure 2, we plot the mole fraction in the
permeate and feed sides in the membrane module. Similar
figures can be easily drawn for the other flow patterns using
the graphical capabilities of Mathematica. Figure 2 clearly
shows that the oxygen mole fraction in the feed side of the
module varies from the inlet value, x,=0.209, to the reject
value, xo=0.1190.
3. Countercurrent-Flow Case
The flow diagram for the countercurrent-flow pattern is
shown in Figure 1. Both streams are in plug flow. The two
governing equations have been derived by Oishi, etal.,1' and
Walawender and Stem 31:

Sqpt dx x-y 1{(1-x)a*(rx-y)- x[r(1-x)-(1 -y)]}
otPB Am y-xo
(11)


S dym x {(- y) (rx- y)- Y[r(1- x)-(1-Y)]}
pqo dA, x-xO
(12)
where qo=(1-6)q,. The following boundary conditions

X m=OX0 and YA=O=Yi

are used where y is the solution of the quadratic equation:


a[xo- ]i
Yi (. xo) PhI y)
1-yi (1-xo)_ Pl (1-yi)
Ph )


We use L'Hopital's rule to compute the derivatives at Am=0
because they become indeterminate when x=xo. This is per-
formed as follows:



Mole
fractions ,,



04
04



02


0 5xlO7 IxlO' 15x10' x 2xl(f 1 25.x l '
Am, (cmn)

Figure 2. Mole fractions of reject and permeate.
Spring 2006


(dy \ (xo-Yi)r[ -y(a*-1)]
dAm Am =0 q {(xo-Yi,)(a* )(2yi-rxo-l)-r}
(Am=0
P|PB f dxa^


(14)


Sdx c (rxo-yi)(xo-yi) (15)
dA-m o t Yi
PIPB)
These two differential equations can be solved simulta-
neously using NDSohle. We enter the equations using an If
statement to take into account the derivative expression when
A ->0:
eql[a_] :=D [x[A] {A, 1}] ==
If[Am == 0,
Evaluate[
(pP') / (q0 t) a (xo ph/ p, yi) (xo- yi)/
yi /.
t-> 2.54 10^-3/. Ph -> 190 /. p -> 19/.
a -> 10/.
P' -> 50 10^-10/. qo -> 8 10^5 /
.xo- a] ,
Evaluate[
(PiP'B)/(qo t) (x[Am] y[Am)/ (y[A -
xo)
((1- x[A] ) a (p/p, x[A] y[Am])-
x[AJ (Ph/p, (1-x[A] ) (l-y[Am] ) ) )/.
t-> 2.54 10"-3/. p -> 190 /. p1 -> 19/.
a -> 10/.
Ps -> 50 10^-10/. qo -> 8 10^5 /
.xo->a] ]
Since the value of the reject mole fraction, xo, and the total
area, Am, are unknown, we use FindRoot to solve for these
two unknowns so that the mole fraction of oxygen in the feed
is 0.209 and that the material balance for component A is
verified:

X Aol =xfA and OyplAsol +(1-O)XOXAf
Following the treatment of Walawender and Stern,'13 we
set the area equal to zero at the outlet of the gas separation
module. Thus, the sign of the membrane area obtained using
this approach is negative and must be reversed. We get the
following results: Aoi=2.859X10" cm2, yp=0.5763, and
xo=0.1171. We find a smaller membrane area and reject mole










fraction and a higher permeate composition.
4. Co-Current-Flow Case
The governing equations"3 are derived in a similar fashion
to the preceding case.

qft dy x
(- {(y)*(rx-y)-[r(1-x)-(l-)]}
p1PB dAm x-xf
(16)

qft dx x-y )a(rx-y)x[r(-x)-(-y)
pPH dAm y -xf
(17)
The following boundary conditions must be used:
XIAm = =XAf and yA, = Yi". The value of y, is a solution of
the following quadratic equation:


Yi [Xf-( Ph yi
Yi_ [ Kh L (18)
1- y )


Inspection of Equation (16) shows that the derivatives are
indeterminate when Am 0. We use L'Hopital's rule to get
expressions for the derivatives at Am=0 as follows:


Sdy
dAm Am=0o


(xf -yi)r[a* -yi(a*- )]

qft {(xf-yi)[(a*-l)(2yi-rxf-1)-r
piPB ( dx )


dAm) o

(19)


dx 1 a*(rxf-yi)(xf-yi) (20)
dAm )Am=0 ft Yi


The value of the total membrane area is found using
FindRoot to satisfy the material balance for oxygen:
yp Asol +(1- )xo =xAf. The membrane area, permeate com-
position, and reject mole fraction are equal to: Ao,=2.955 X 108
cm2, yp=0.5584 and xo=0.1216.
5. Comparing the Different Flow Patterns
The membrane areas are equal within 10%. The smallest
membrane area is obtained using the countercurrent flow
pattern. The countercurrent case requires a smaller membrane
area because the driving force for permeation (the composi-


tion difference between permeate and feed sides) is higher
than in the other flow patterns. The complete-mixing model
gives the highest membrane area. The reject mole fractions
and the permeate compositions obtained for the four cases
studied show similar trends. The most efficient flow pattern
is the countercurrent mode. In fact, the order of efficiency is
the following: countercurrent flow > cross-flow > co-current
flow > complete-mixing model. Reducing membrane area
has a major impact on capital investment costs. Thus, the
countercurrent flow pattern is the optimal design choice. Other
relevant parameters for reducing membrane area are thick-
ness and permeability of the membrane and operating pres-
sure, which will affect operating costs as well.

CONCLUSIONS
In this study, we showed how simple Mathematica com-
mands[2' can be used to solve problems that required tedious
iterative techniques or complicated programming skills. We
present the solutions of two problems proposed by Professor
Geankoplis.111 We extend this author's work to the counter-
current and co-current flow patterns. These problems are given
to the junior and senior students of the National Institute of
Applied Sciences in Tunis as small research projects. The
students excel in these type of problems despite the fact that
they do not have prior knowledge of Mathematica.

NOMENCLATURE
A membrane area
Pi permeability of component i
Ph feed side pressure
p, permeate side pressure
qf feed flow rate
qp permeate flow rate
q. reject flow rate
t membrane thickness
r ratio of pressures of feed and permeate sides
x, feed mole fraction of component i
xo reject mole fraction
y, permeate mole fraction
a* separation factor
0 stage cut

REFERENCES
1. Geankoplis, C.J., Transport Processes and Unit Operations, 3rd Ed.,
Prentice Hall, Upper Saddle River, NJ (1993) (example 13.5-1, page
771 and example 13.4-2, page 767)
2. ?search_results=1;search_person_id=1536>
3. Walawender, W.P., and S.A. Stem, Separation Science, 7 5, 553-584
(1972)
4. Oishi, J., Y. Matsumura, K. Higashi, and C. Ike, J. At. Energy Soc.
Japan, 3, 923 (1961) O


Chemical Engineering Education


























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