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Aerosol formation from atmospheric hydrocarbon photooxidation

Citation

Forstner, Hali J. L. (1996) Aerosol formation from atmospheric hydrocarbon photooxidation. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-12182007-114559

Abstract

Outdoor smog chamber experiments have been performed to determine the secondary organic aerosol (SOA) formation potential of various C7, C8, and C9 aromatics in sunlight-irradiated hydrocarbon- NO[subscript x] mixtures. Measured aerosol yields from toluene,m-xylene, p -xylene, ethylbenzene, m -ethyltoluene, p-ethyltoluene, and 1 ,2,4-trimethylbenzene were found to correlate with organic mass concentration according to semi-volatile gas/particle partitioning theory. Aerosol yields of the C9 aromatics were greater than those of the C8 aromatics, with m-ethyltoluene resulting in the greatest yields. Toluene and ethylbenzene demonstrated some aerosol-forming potential, but the other aromatics produced significantly more SOA.

Filter samples were also collected during the experiments to determine the molecular composition of the SOA from these aromatics Gas-phase mechanisms leading to these products have been proposed. Unsaturated anhydrides (2,5-furandione, 3-methyl-2,5-furandione, 3-ethyl-2,5-furandione) are predominant components of aerosol from all the aromatics, an observation that is consistent with gas-phase aromatic mechanisms involving ring-fragmentation. Saturated anhydrides were also detected in significant quantities, which could result from the hydrogenation of furandiones in sunlight in the particle phase. A new organic aerosol extraction procedure utilizing supercritical CO2 extraction is outlined.

Outdoor smog chamber experiments were also performed to characterize aerosol from 1-octene and 1-decene photooxidation. The dominant aerosol species were heptanal, heptanoic acid, and dihydro-5-propyl-2(3H)-furanone from 1-octene, and nonanal, nonanoic acid, and dihydro-5-pentyl-2(3H)-furanone from 1-decene. Gas-phase oxidation mechanisms of 1-octene and 1-decene with OH and O3 account for the aerosol products.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Environmental Science and Engineering
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Seinfeld, John H. (advisor)
  • Flagan, Richard C. (advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:23 May 1996
Record Number:CaltechETD:etd-12182007-114559
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-12182007-114559
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5054
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:18 Jan 2008
Last Modified:26 Dec 2012 03:14

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