Multiphase interactions between sulfur dioxide and secondary organic aerosol from the photooxidation of toluene: Reactivity and sulfate formation

Qing Ye; Min Yao; Wei Wang; Ziyue Li; Chenxi Li; Shunyao Wang; Huayun Xiao; Yue Zhao

doi:10.1016/j.scitotenv.2023.168736

Multiphase interactions between sulfur dioxide and secondary organic aerosol from the photooxidation of toluene: Reactivity and sulfate formation

Sci Total Environ. 2024 Feb 20:912:168736. doi: 10.1016/j.scitotenv.2023.168736. Epub 2023 Nov 21.

Authors

Qing Ye¹, Min Yao², Wei Wang¹, Ziyue Li¹, Chenxi Li¹, Shunyao Wang³, Huayun Xiao¹, Yue Zhao⁴

Affiliations

¹ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
² School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China.
³ School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
⁴ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: yuezhao20@sjtu.edu.cn.

PMID: 37996034
DOI: 10.1016/j.scitotenv.2023.168736

Abstract

There is growing evidence that the interactions between sulfur dioxide (SO₂) and organic peroxides (POs) in aerosol and clouds play an important role in atmospheric sulfate formation and aerosol aging, yet the reactivity of POs arising from anthropogenic precursors toward SO₂ remains unknown. In this study, we investigate the multiphase reactions of SO₂ with secondary organic aerosol (SOA) formed from the photooxidation of toluene, a major type of anthropogenic SOA in the atmosphere. The reactive uptake coefficient of SO₂ on toluene SOA was determined to be on the order of 10^-4, depending strikingly on aerosol water content. POs contribute significantly to the multiphase reactivity of toluene SOA, but they can only explain a portion of the measured SO₂ uptake, suggesting the presence of other reactive species in SOA that also contribute to the particle reactivity toward SO₂. The second-order reaction rate constant (k^II) between S(IV) and toluene-derived POs was estimated to be in the range of the k^II values previously reported for commercially available POs (e.g., 2-butanone peroxide and 2-tert-butyl hydroperoxide) and the smallest (C₁-C₂) and biogenic POs. In addition, unlike commercial POs that can efficiently convert S(IV) into both inorganic sulfate and organosulfates, toluene-derived POs appear to mainly oxidize S(IV) to inorganic sulfate. Our study reveals the multiphase reactivity of typical anthropogenic SOA and POs toward SO₂ and will help to develop a better understanding of the formation and evolution of atmospheric secondary aerosol.

Keywords: Multiphase reactions; Organic peroxides; Secondary organic aerosol; Sulfate aerosol; Sulfur dioxide; Toluene.