Issue 45, 2023

An overlooked oxidation mechanism of toluene: computational predictions and experimental validations

Abstract

Secondary organic aerosols (SOAs) influence the Earth's climate and threaten human health. Aromatic hydrocarbons (AHs) are major precursors for SOA formation in the urban atmosphere. However, the revealed oxidation mechanism dramatically underestimates the contribution of AHs to SOA formation, strongly suggesting the importance of seeking additional oxidation pathways for SOA formation. Using toluene, the most abundant AHs, as a model system and the combination of quantum chemical method and field observations based on advanced mass spectrometry, we herein demonstrate that the second-generation oxidation of AHs can form novel epoxides (TEPOX) with high yield. Such TEPOX can further react with H2SO4 or HNO3 in the aerosol phase to form less-volatile compounds including novel non-aromatic and ring-retaining organosulfates or organonitrates through reactive uptakes, providing new candidates of AH-derived organosulfates or organonitrates for future ambient observation. With the newly revealed mechanism, the chemistry-aerosol box modeling revealed that the SOA yield of toluene oxidation can reach up to 0.35, much higher than 0.088 based on the original mechanism under the conditions of pH = 2 and 0.1 ppbv NO. This study opens a route for the formation of reactive uptake SOA precursors from AHs and significantly fills the current knowledge gap for SOA formation in the urban atmosphere.

Graphical abstract: An overlooked oxidation mechanism of toluene: computational predictions and experimental validations

Supplementary files

Article information

Article type
Edge Article
Submitted
14 Jul 2023
Accepted
26 Oct 2023
First published
27 Oct 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2023,14, 13050-13059

An overlooked oxidation mechanism of toluene: computational predictions and experimental validations

Z. Fu, F. Ma, Y. Liu, C. Yan, D. Huang, J. Chen, J. Elm, Y. Li, A. Ding, L. Pichelstorfer, H. Xie, W. Nie, J. S. Francisco and P. Zhou, Chem. Sci., 2023, 14, 13050 DOI: 10.1039/D3SC03638C

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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