Document Detail

A transient model of mass transfer and kinetics in a passive vapor sampler.
MedLine Citation:
PMID:  7502993     Owner:  NLM     Status:  MEDLINE    
A transient model of vapor contaminant diffusion and homogeneous reaction in a two-compartment passive sampler was formulated. The mathematical analysis considered finite reaction kinetics, bulk air boundary-layer effects, and the solubility of the vapor contaminant in the liquid absorbing/reacting medium. The model was evaluated using experimentally measured Cl2 uptake rates in a series of samplers of different dimensions containing a 0.1% aqueous sulfamic acid solution in the absorbing medium chamber. The theory predicts accurately the effects of sampler diameter, stagnant air chamber path length, and sampler orientation with respect to the flowing air on Cl2 uptake, with an average error of less than 10%. Chlorine uptake in a 33-mm diameter sampler with a 10.8-mm path length was found to be essentially independent of wind direction and varied by approximately 23% for wind speeds ranging from 5.1 to 203 cm s-1 (10-400 ft min-1). Calculations show that the sampler is sensitive to wind speed partly because of the Cl2 hydrolysis reaction, which produces HOCl and drops the vapor phase concentration of chlorine to near zero at the stagnant air/absorbing medium chamber interface, regardless of the rate of homogeneous reaction between HOCl and sulfamate anions. If the solubility of the vapor contaminant in the liquid absorbing medium were to obey Henry's Law (no hydrolysis reaction) and the homogeneous trapping reaction were sufficiently slow, then model calculations show that contaminant uptake could be controlled solely by reaction kinetics, although the sampling rates would be lower than those observed and predicted for the Cl2 case.
C E Williams; P N Pintauro; R J Rando
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  American Industrial Hygiene Association journal     Volume:  56     ISSN:  0002-8894     ISO Abbreviation:  Am Ind Hyg Assoc J     Publication Date:  1995 Nov 
Date Detail:
Created Date:  1996-01-16     Completed Date:  1996-01-16     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0371160     Medline TA:  Am Ind Hyg Assoc J     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1074-82     Citation Subset:  IM    
Tulane University, Department of Chemical Engineering, New Orleans, LA 70118, USA.
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MeSH Terms
Air Pollutants, Occupational / analysis*
Chlorine / analysis
Environmental Monitoring / instrumentation*,  methods
Models, Theoretical*
Grant Support
Reg. No./Substance:
0/Air Pollutants, Occupational; 7782-50-5/Chlorine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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