Environment Research Institute, Shandong University, Qingdao, 266237, PR China.
Environment Research Institute, Shandong University, Qingdao, 266237, PR China.
Chemosphere. 2020 Nov;259:127331. doi: 10.1016/j.chemosphere.2020.127331. Epub 2020 Jun 25.
The atmospheric degradation of polycyclic aromatic hydrocarbons (PAHs) can generate organic pollutants that contribute to the formation of secondary organic aerosols (SOAs) and exacerbate their carcinogenicity. Indene is an example of styrene-like bicyclic hydrocarbons that are not fully aromatic. The OH-initiated atmospheric oxidation of indene in the presence of O and NO was investigated using quantum chemical methods at M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p) level. The oxidation products are oxygenated polycyclic aromatic hydrocarbons (OPAHs) containing hydroxyindene, indenone, dialdehydes and 2-(formylmethyl)benzaldehyde. Calculation results showed that 7-indene radical, which is the precursor of various PAHs, has a high production ratio that is 35.29% in the initial reaction, indicating that the OH-initiated oxidation increase the environmental risks of indene in the atmosphere. The rate constants for the crucial elementary reactions were calculated based on Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The overall rate constant of the initial reaction is calculated to be 1.04 × 10 cm molecule s and the atmospheric lifetime of indene is determined as 2.74 h. This work provides a comprehensive understanding on the oxidation mechanisms of indene and the findings could help to clarify the fate of indene in the atmosphere.
多环芳烃（PAHs）在大气中的降解会生成有机污染物，这些污染物有助于二次有机气溶胶（SOAs）的形成，并加剧其致癌性。茚是一种具有部分不饱和结构的苯乙烯型双环烃类化合物。本研究采用量子化学方法，在 M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p)水平上，研究了在 O 和 NO 存在下，OH 引发的茚的大气氧化反应。氧化产物是含氧多环芳烃（OPAHs），包括羟基茚、茚酮、二醛和 2-（甲酰甲基）苯甲醛。计算结果表明，作为各种 PAHs 前体的 7-茚基自由基在初始反应中的生成比例高达 35.29%，这表明 OH 引发的氧化会增加大气中茚的环境风险。根据 Rice-Ramsperger-Kassel-Marcus（RRKM）理论，计算了关键基元反应的速率常数。初始反应的总速率常数计算为 1.04×10 cm 分子 s，茚在大气中的停留时间为 2.74 h。这项工作提供了对茚氧化机制的全面理解，研究结果有助于阐明茚在大气中的归宿。
