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Kinetics and Products of Heterogeneous Hydroxyl Radical Oxidation of Isoprene Epoxydiol-Derived Secondary Organic Aerosol



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  • Personal Author:
  • Description:
    Heterogeneous hydroxyl radical (·OH) oxidation is an important aging process for isoprene epoxydiol-derived secondary organic aerosol (IEPOX-SOA) that alters its chemical composition. It was recently demonstrated that heterogeneous ·OH oxidation can age single-component particulate methyltetrol sulfates (MTSs), causing approx. 55% of the SOA mass loss. However, our most recent study of freshly generated IEPOX-SOA particulate mixtures suggests that the lifetime of the complete IEPOX-SOA mixture against heterogeneous ·OH oxidation can be prolonged through the fragmentation of higher-order oligomers. Published studies suggest that the heterogeneous ·OH oxidation of IEPOX-SOA could affect the organic atmospheric aerosol budget at varying rates, depending on aerosol chemical composition. However, heterogeneous ·OH oxidation kinetics for the full IEPOX-SOA particulate mixture have not been reported. Here, we exposed freshly generated IEPOX-SOA particles to heterogeneous oxidation by ·OH under humid conditions (relative humidity approx. 57%) for 0-15 atmospheric-equivalent days of aging and derived an effective heterogeneous ·OH rate coefficient (kOH) of 2.64 +/- 0.4 × 10-13 cm3 molecules-1 s-1. While approx. 44% of particulate organic mass of nonoxidized IEPOX-SOA was consumed over the entire 15 day aging period, only <7% was consumed during the initial 10 aging days. By molecular-level chemical analysis, we determined oligomers were consumed at a faster rate (by a factor of 2-4) than monomers. Analysis of aerosol physicochemical properties shows that IEPOX-SOA has a core-shell morphology, and the shell becomes thinner with ·OH oxidation. In summary, this study demonstrates that heterogeneous ·OH oxidation of IEPOX-SOA particles is a dynamic process in which aerosol chemical composition and physicochemical properties play important roles. [Description provided by NIOSH]
  • Subjects:
  • Keywords:
  • ISSN:
    2472-3452
  • Document Type:
    Text
  • Funding:
    Grant
  • Genre:
    Journal Article
  • Place as Subject:
  • CIO:
    National Institute for Occupational Safety and Health (NIOSH)
  • Topic:
    Workplace Safety & Health
  • Location:
    North America
  • Volume:
    7
  • Issue:
    10
  • NIOSHTIC Number:
    nn:20068706
  • Citation:
    ACS Earth Space Chem 2023 Oct; 7(10):1916-1928
  • Contact Point Address:
    Andrew P. Ault, Department of Chemistry, College of Literature Sciences and the Arts, University of Michigan, Ann Arbor, Michigan 48109, United States
  • Email:
    aulta@umich.edu
  • Federal Fiscal Year:
    2024
  • Performing Organization:
    University of North Carolina, Chapel Hill
  • Peer Reviewed:
    True
  • Start Date:
    20050701
  • Source Full Name:
    ACS Earth and Space Chemistry
  • End Date:
    20270630
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:ae595e06a74699c0888a05676c5dea1f69146fd64d8e00d4a89222f850563ed9bf72b7de3b86f35dc4d5bc04dcf959404018ab8f9fe19ccdc866bdb7f068752d
  • Download URL:
  • File Type:
    Filetype[PDF - 3.70 MB ]
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