Document Detail


Reaction of isoprene on thin sulfuric acid films: kinetics, uptake, and product analysis.
MedLine Citation:
PMID:  20499904     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A high vacuum Knudsen flow reactor was used to determine the reactive uptake coefficient, gamma, of isoprene on sulfuric acid films as a function of sulfuric acid weight percent, temperature, and relative humidity. No discernible dependence was observed for gamma over the range of temperatures (220 - 265 K) and pressures (10(-7) Torr -10(-4) Torr) studied. However, the uptake coefficient increased with increased sulfuric acid concentration between the range of 78 wt % (gamma(i) approximately 10(-4)) and 93 wt % (gamma(i) approximately 10(-3)). In addition to the Knudsen Cell, a bulk study was conducted between 60 and 85 wt % H(2)SO(4) to quantify uptake at lower acid concentrations and to determine reaction products. After exposing sulfuric acid to gaseous isoprene the condensed phase products were extracted and analyzed using gas chromatography/mass spectrometry (GC/MS). Isoprene was observed to polymerize in the sulfuric acid and form yellow/red colored monoterpenes and cyclic sesquiterpenes. Finally, addition of water to the 85 wt % sulfuric acid/isoprene product mixture released these terpenes from the condensed phase into the gas phase. Together these experiments imply that direct isoprene uptake will not produce significant SOA; however, terpene production from the small uptake may be relevant for ultrafine particles and could affect growth and nucleation.
Authors:
Brandon M Connelly; Margaret A Tolbert
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Environmental science & technology     Volume:  44     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-06-11     Completed Date:  2010-08-06     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4603-8     Citation Subset:  IM    
Affiliation:
The Cooperative Institute for Research in Environmental Sciences, The Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0216, USA.
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MeSH Terms
Descriptor/Qualifier:
Atmosphere / chemistry
Butadienes / chemistry*
Gas Chromatography-Mass Spectrometry
Gases / chemistry
Hemiterpenes / chemistry*
Kinetics
Pentanes / chemistry*
Sulfuric Acids / chemistry*
Time Factors
Chemical
Reg. No./Substance:
0/Butadienes; 0/Gases; 0/Hemiterpenes; 0/Pentanes; 0/Sulfuric Acids; 7664-93-9/sulfuric acid; 78-79-5/isoprene

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


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