Understanding the role of Cl and NO3 radicals in initiating atmospheric oxidation of fluorene: A mechanistic and kinetic study.
Understanding the role of Cl and NO3 radicals in initiating atmospheric oxidation of fluorene: A mechanistic and kinetic study.
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DOI：
10.1016/j.scitotenv.2020.136905
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
Zhezheng Ding;Yayi Yi;Wen-xing Wang;Qingzhu Zhang
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文献类型：
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作者：
Zhezheng Ding;Yayi Yi;Wen-xing Wang;Qingzhu Zhang
几十年来，人们一直在研究由 Cl 和 NO3 自由基引发的挥发性有机化合物 (VOC) 的光氧化作用，以评估污染物在大气中的归宿。气相芴是最丰富的多环芳烃（PAH）之一，可被活化自由基氧化。在本研究中，我们利用量子化学计算研究了Cl和NO3自由基引发的芴在大气中的降解过程。结果表明，Cl自由基引发的芴反应主要产生9-芴自由基，该自由基极有可能形成具有更持久毒性的二次污染物。 NO3 自由基引发的芴反应导致氧化多环芳烃 (OPAH) 和硝化多环芳烃 (NPAH) 的形成，包括硝基氧基芴、硝基氧基芴酮和 1,4-芴醌。基元反应的速率常数和支链比根据Rice-Ramsperger-Kassel-Marcus (RRKM) 理论确定。根据计算的总速率常数1.52 × 10−14cm3molecule−1s−1，推算出NO3自由基测定的芴在大气中的寿命为1.52天。由Cl和NO3自由基引发的芴在大气中降解产生的衍生物增加了芴的环境风险。结合之前的实验和理论发现，这项工作有助于阐明芴的大气归宿并评估芴的环境风险。
The photooxidation of volatile organic compounds (VOCs) initiated by Cl and NO3radicals has been investigated for decades to assess the atmospheric fates of pollutants. Gas-phase fluorene is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) that can be oxidized by activated radicals. In this study, we used quantum chemical calculation to study the atmospheric degradation of fluorene initiated by Cl and NO3radicals. The results showed that the Cl radical initiated reaction of fluorene mainly produces 9-fluorene radical that has significant potential to form secondary pollutants with more persistent toxic properties. The NO3radical initiated reaction of fluorene leads to the formation of oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) including nitrooxyfluorene, nitrooxyfluorenone and 1,4-fluorenequinone. The rate constants and branch ratios of elementary reactions were determined based on Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The atmospheric lifetime of fluorene determined by NO3radical is deduced to be 1.52 days according to the calculated overall rate constant, 1.52 × 10−14cm3molecule−1s−1. The derivatives produced from the atmospheric degradation of fluorene initiated by Cl and NO3radicals increase the environmental risks of fluroene. Combined with previous experimental and theoretical findings, this work can help to clarify the atmospheric fate and assess the environmental risks of fluorene.