| Title: | Multigeneration Production of Secondary Organic Aerosol from Toluene Photooxidation |
| Author(s): | Li Y; Zhao J; Wang Y; Seinfeld JH; Zhang R; |
| Address: | "Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, United States. Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States. Department of Atmospheric Sciences, Texas A&M University, College Station, Texas 77843, United States" |
| ISSN/ISBN: | 1520-5851 (Electronic) 0013-936X (Linking) |
| Abstract: | "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 NH(3)) 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" |
| Keywords: | Aerosols Gases Oxidation-Reduction *Toluene *Volatile Organic Compounds aerosol-phase reactions functionality photooxidation secondary organic aerosol toluene; |
| Notes: | "MedlineLi, Yixin Zhao, Jiayun Wang, Yuan Seinfeld, John H Zhang, Renyi eng Research Support, Non-U.S. Gov't 2021/06/18 Environ Sci Technol. 2021 Jul 6; 55(13):8592-8603. doi: 10.1021/acs.est.1c02026. Epub 2021 Jun 17" |
