Diffusional Release of Pollutants into Ambient Air and Method for Enhancing Diffusional Collection in Air Sampling

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Material Information

Title:
Diffusional Release of Pollutants into Ambient Air and Method for Enhancing Diffusional Collection in Air Sampling
Physical Description:
1 online resource (139 p.)
Language:
english
Creator:
Shou, Lin
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Environmental Engineering Sciences
Committee Chair:
WU,CHANG-YU
Committee Co-Chair:
KOOPMAN,BEN L
Committee Members:
TOWNSEND,TIMOTHY G
POWERS,KEVIN WILLIAM
HSU,YU-MEI
BIRKY,BRIAN K

Subjects

Subjects / Keywords:
acids -- air -- ammonia -- diffusion -- exposure -- modeling -- sampler
Environmental Engineering Sciences -- Dissertations, Academic -- UF
Genre:
Environmental Engineering Sciences thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
In this study, a personal sampler relying on diffusional collection of acidic gases was developed, and diffusional release of ammonia from concrete was characterized. The personal sampler consists with a parallel impactor, a porous membrane denuder and a filter pack. Experiments demonstrated that the entire personal sampler’s collection efficiency for SO2, HCl and HNO3 of twice OSHA standard was higher than 95% for four hours. It could collect more than 99% of aerosols within eight hours, and the interference between acidic gas and aerosols was effectively minimized.To identify the potential release of ammonia from ammoniated fly ash in concrete, laboratory-scale exposure experiments with fly ash of different ammonium contents added to concrete were carried out. This study showed that in the concrete mixing and initial settling periods, ammonia gas was quickly released into ambient air. In the concrete curing period, the ammonia gas release rate gradually decreased due to decreased moisture content and filled pore spaces of the concrete specimen until its concentration became below the detection limit of the ion chromatography system (below ppm level). Although the entire ammonia emitting process could last several weeks, over 80% of the released ammonia gas was emitted in the first 8 hours after the concrete was mixed. In considering worker health and safety, a semi-infinite diffusion model was applied to analyze the first 8-hr experimental data and an “effective” diffusion coefficient (Deff) was derived to manifest the effects caused by phase and geometry changes in the concrete hardening process. Due to forced convection, Deff in the mixing period, which was 0.098 cm2/s, was much larger than that of the initial settling period, which was 0.0038 cm2/s.  The semi-infinite diffusion model and the “effective” diffusion coefficients were applied in typical working scenarios of concrete construction to estimate workers’ exposure level to released ammonia. Based on the results from simulation and experiments, a safe threshold of 100 ppm of ammonia content in fly ash was recommended to regulators and the fly ash industry.
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Lin Shou.
Thesis:
Thesis (Ph.D.)--University of Florida, 2013.
Local:
Adviser: WU,CHANG-YU.
Local:
Co-adviser: KOOPMAN,BEN L.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2014-12-31

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2013
System ID:
UFE0045820:00001