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Multigeneration Production of Secondary Organic Aerosol from Toluene Photooxidation

Li, Yixin and Zhao, Jiayun and Wang, Yuan and Seinfeld, John H. and Zhang, Renyi (2021) Multigeneration Production of Secondary Organic Aerosol from Toluene Photooxidation. Environmental Science and Technology, 55 (13). pp. 8592-8603. ISSN 0013-936X. doi:10.1021/acs.est.1c02026.

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Photooxidation of volatile organic compounds (VOCs) produces secondary organic aerosol (SOA) and light-absorbing brown carbon (BrC) via multiple reaction steps/pathways, reflecting significant chemical complexity relevant to gaseous oxidation and subsequent gas-to-particle conversion. Toluene is an important VOC under urban conditions, but the fundamental chemical mechanism leading to SOA formation remains uncertain. Here, we elucidate multigeneration SOA production from toluene by simultaneously tracking the evolutions of gas-phase oxidation and aerosol formation in a reaction chamber. Large size increase and browning of monodisperse sub-micrometer seed particles occur shortly after initiating oxidation by hydroxyl radical (OH) at 10–90% relative humidity (RH). The evolution in gaseous products and aerosol properties (size/density/optical properties) and chemical speciation of aerosol-phase products indicate that the aerosol growth and browning result from earlier generation products consisting dominantly of dicarbonyl and carboxylic functional groups. While volatile dicarbonyls engage in aqueous reactions to yield nonvolatile oligomers and light-absorbing nitrogen heterocycles/heterochains (in the presence of NH₃) at high RH, organic acids contribute to aerosol carboxylates via ionic dissociation or acid–base reaction in a wide RH range. We conclude that toluene contributes importantly to SOA/BrC formation from dicarbonyls and organic acids because of their prompt and high yields from photooxidation and unique functionalities for participation in aerosol-phase reactions.

Item Type:Article
Related URLs:
URLURL TypeDescription
Li, Yixin0000-0001-7937-7385
Wang, Yuan0000-0001-6657-8401
Seinfeld, John H.0000-0003-1344-4068
Zhang, Renyi0000-0001-8708-3862
Additional Information:© 2021 American Chemical Society. Received: March 29, 2021; Revised: May 19, 2021; Accepted: May 20, 2021; Published: June 17, 2021. R.Z. acknowledged the support by the Robert A. Welch Foundation (Grant A-1417). Y.L. was supported by a dissertation Fellowship at Texas A&M University. The authors declare no competing financial interest.
Funding AgencyGrant Number
Robert A. Welch FoundationA-1417
Texas A&M UniversityUNSPECIFIED
Subject Keywords:secondary organic aerosol, photooxidation, toluene, aerosol-phase reactions, functionality
Issue or Number:13
Record Number:CaltechAUTHORS:20210626-183437572
Persistent URL:
Official Citation:Multigeneration Production of Secondary Organic Aerosol from Toluene Photooxidation. Yixin Li, Jiayun Zhao, Yuan Wang, John H. Seinfeld, and Renyi Zhang. Environmental Science & Technology 2021 55 (13), 8592-8603; DOI: 10.1021/acs.est.1c02026
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109598
Deposited By: George Porter
Deposited On:28 Jun 2021 16:26
Last Modified:16 Nov 2021 19:36

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