The autoreduction of AM(VI) and AM(V) in dilute acid

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Material Information

Title:
The autoreduction of AM(VI) and AM(V) in dilute acid
Physical Description:
4 p. : ill. ; 27 cm.
Language:
English
Creator:
Asprey, L. B
Stephanou, S. E
U.S. Atomic Energy Commission
Los Alamos Scientific Laboratory
Publisher:
U.S. Atomic Energy Commission, Technical Information Division
Place of Publication:
Oak Ridge, Tenn
Publication Date:

Subjects

Subjects / Keywords:
Americium   ( lcsh )
Reduction (Chemistry)   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references.
Statement of Responsibility:
by L.B. Asprey, S.E. Stephanou.
General Note:
Cover title.
General Note:
"AECU-924."
General Note:
"November 10, 1950 TIS Issuance Date."
General Note:
Work performed at the Los Alamos Scientific Laboratory.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 005254591
oclc - 702220268
System ID:
AA00008505:00001

Full Text
~


w2L


UNITED STATES ATOM


C ENERGY


COMMISSION


AECU-924


THE AUTOREDUCTION OF


AM(VI)


AND AM(V)


IN DILUTE ACID


B. Asprey


E. Stephanou


L


November


[TIS


1950


Issuance Date]


Los Alamos Scientific Laboratory


Technical Information Division,


ORE,


Oak Ridge,


Tennessee


I


Ats


I






















Styled,


retyped,


and reproduced from


copy


as submitted


to this


office


Work performed
No. W-740



PRINTED I
PRICE 5


under Contract


N U.S.A.
CENTS


SI















THE AUTOREDUCTION


OF AM(VI)


AND AM(V)


IN DILUTE ACID*


L. B. Asprey and


S. E.


Stephanou


In various


always


duction of


studies


observed
Am(V) to


that
Am(I


0

I


in order to determine the
quantitative expression f
Rate studies were ma
concentration, americium


species of
different


i


americium, a
onic species


n the higher
reduction of
I) occurred.
cause of th


or the


de,


oxidation states


Am(VI)
This


is


to Am(V)
phenomenon


of americium,


followed


by the


it
re-


was investigated


reduction and to establish a


rate.


varying such factors


concentration,


nd the


ionic


the ratio


strength.


of americium was


as the
of the


hydrogen
various


concentration


Sion
ionic
of the


determined -spectrophotometrically


with
volume


the Model DU Beckman spectrophotometer
es of the order of 100 jl. Perchloric


and quartz microcells,
acid solutions were us


ie


using
d in


the range 0.
formation.
pure. Conce
ionic strong
The pre
oxidation at
alkaline hyp
Perlman.


iii


against
auction
species.


Am(v)


with


time,


035 to
The am


1.014


eric


ntrations


th


in all


one experiment


to avoid


complex


cent


ium used in the studies was greater than 9
of americium varied from 0.008M to 0.033M.


was adjusted


part ion
about 85
ochlorite


concentration
a straight li


by means


Am(VI) was ac
Preparation
-~75C accord


of Am(
ne was


a zero order reaction


Figure
Only a


1 shows


that Am(


very small growth of


reaching a maximum concentration


when


of sodium


hieved


of Am(V)


ing to


VI), Am(V),
obtained.


perchlorate.


by means


was carr


the method


or Am(III)


This


of peroxydisulfate


ied out using
of Werner and


was plotted


indicates


with respect to the
VI) in 1M perchloric


Am( III).
the Am(VI)


Am(V)


that


t


particular io
acid reduces


he re-
nic
to


increased linearly,


was completely reduced


Then Am(V)


reduced linearly to Am(III)


at approximately half the Am(VI)


reduction rate.


In Table 1, rates of reduction occurri
concentrations of americium are tabulated.

*Manuscript for a 15-minute talk given
meeting of the American Chemical Society on


ng at


Septem


a number


of different


B. Asprey at
ber 5, 1950,


the Chicago


based


work performed at
of California.


the Los Alamos


Scientific


Laboratory


of the University


was


When the


~E:E.









AXCU-921F


Table


1--Experimental Results;


Postulated Rate Law:


-d Am(V)/dt


= k (Am)


Rate of


change,


(M x 103)


k,(Moles Am(V)


Reduced)


(liter


hour)


(Moles Am hour)


Acid


Total Am,
Moles/liter


-d(Am(V))


+dmII I))


Am(V)


Am( III)


HCIO
HCIO

HC104


0.009


0.033
0.016


0.20
0.62
0.70
0.39


0.21
0.66
0.73
0.42


Average


0.022
0.025
0.021
0.024


0.023
0.026
0.022
0.026

0.024


0.023


HCI04
HClO4
HC104
HCIOg
HCIO4
H2304


0.035
0.1


0.023
0.011
0.008
0.009
o.0o16


0.83
0.22
0.14
0.15
0.25


0.83
0.25
0.15
0.15
0.26


0.036
0.020
0.018
0.017
0.016


0.036
0.023
0.019
0.017
0.016


It can be seen that the reduction


total concentration of


a particular
fair agreement


hydrogen i


is first order with respect to the


americium for the reduction of Am(V) to (III).
on concentration, the values of k obtained are


In the one experiment in 0.5M HClO4


an abnormally high


value was


obtained.


In the experiments


on the reduction of Am(VI)


of k were found to be 0.046 and
As would be expected, these va


for the reduction of Am(V).to Am(III),
volved.


These results


since


suggest that the reducti


lowed by the reduction of Am(V)
reacting with the water. Proba


to Am(III)


0.054 in 1 and 0.5M HCl4,
lues are about twice those
only one equivalent is in-


on of Am(VI) to Am(V) fol-
is caused by the Am241 alphas


Bible reductants formed by the reaction of


alphas
volved.
solution
has bee


with water are H202 and H atoms
Throughout the reduction, gas


ns
n m


but other fragments may be in-
was evolved from the americium


but no determination of the amount or composition of the gas
ade in the present study.


The variation in


the rate constant may be due


in part to a small


effect of
factor is
adventitio


degree


th


.e hydrogen ion concentration.


Probably a more


important


the variation between solutions due to small amounts of
us impurities which decompose the reducing agent or change the


of recombination of the water fragments.


If the


products


of the alpha radiation


of water cause this reduction,


then the rate of reduction should be a function of the americium half-life


and the


energy of


its alpha radiation.


A calculation showing the number


of electron
of Am(V) re


volts available from alpha radiation in terms of


duced to Am(III)


one equivalent


is given herewith.


values


respectively.


1


Am(V)









AECU-924


Calculation


of the number


of ev/molecule


At. Wt.


d/m/g of
7x 1012


of Am
241


d/m/to d/hr
60


of Am(V) re

ev/alpha
from Am241


5.47


x 106


duced by


ev/mol
= 5.55


IM HCI04


e Am/hr
x 1023


0.024* x


1023


6.02 x 1023


mole Am hr
molecules Am(V) reduced


mole Am


- hr


= 38 ev/molecule
Am(V) reduced


Am(III)


or 19 ev/per


equivalent


*Average


value


of kr from four


experiments


in 1M HCO104


summary
d inl M


and Scheuer in
values found b


Table


(H+)

1.1
1.0
1.0
1.0
0.5
0.3
0.1
0.035
0.1


'of the result
HCIO4 agrees
experiments


y a number


2--Electron


1. A

1.1 BH
1.1 Hi
1.0 H
1.0 iH
1.1 Hi
1.0 H
0.1 B
1.1 H
0.3 H,


appears


well


with


in Table
the value


using radon as


of investigators


Volts


per Equiva


value


of 20 ev foun


the alpha source.


cover the range



lent of Am(V) I


ev/equivalent
Am(V) reduced

20
18


cid

C104
C10
C10g
C10;
0104
clo
C10
C10i
CSO,
~204


from


of 19 ev
d by Duane


However,


20 to 80 ev.


reduced


ev/equivalent
Am(VI) reduced


20


The reduction


species


of Am(VI)


being reduced and first


and Am(V)


is zero order with respect


order with respect


to the


to the


total americium


concentration.


These


the reaction of the


results


can


americium alpha


be satisfactorily explained as


particles


with water.


Since


due to
other


workers have found H202 to
alpha particles and water,


be
thi


a princip
s offers


le


product


of the reaction


between


a reasonable explanation for the


reduction


observed.


No direct experiments


have


been made to determine


whether


a hydrogen


peroxide mechanism is


involved.


A
obtain


5.55 x












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