Assessing the role of mineral particles in the atmospheric photooxidation of typical carbonyl compound

Taicheng An , Yongpeng Ji , Xingyu Chen , Yuqi Xiao , Yuemeng Ji , Weina Zhang , Jiaxin Wang , Jiangyao Chen , Guiying Li


Received October 23, 2020,Revised , Accepted December 21, 2020, Available online January 14, 2021

Volume 33,2021,Pages 56-63

Mineral particles are ubiquitous in the atmosphere and exhibit an important effect on the photooxidation of volatile organic compounds (VOCs). However, the role of mineral particles in the photochemical oxidation mechanism of VOCs remains unclear. Hence, the photooxidation reactions of acrolein (ARL) with OH radical (OH) in the presence and absence of SiO2 were investigated by theoretical approach. The gas-phase reaction without SiO2 has two distinct pathways (H-abstraction and OH-addition pathways), and carbonyl-H-abstraction is the dominant pathway. In the presence of SiO2, the reaction mechanism is changed, i.e., the dominant pathway from carbonyl-H-abstraction to OH-addition to carbonyl C-atom. The energy barrier of OH-addition to carbonyl C-atom deceases 21.33 kcal/mol when SiO2 is added. Carbonyl H-atom of ARL is occupied by SiO2 via hydrogen bond, and carbonyl C-atom is activated by SiO2. Hence, the main product changes from H-abstraction product to OH-adduct in the presence of SiO2. The OH-adduct exhibits a thermodynamic feasibility to yield HO2 radical and carboxylic acid via the subsequent reactions with O2, with implications for O3 formation and surface acidity of mineral particles.

Copyright © Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.京ICP备05002858号-3