Theoretical model on the formation possibility of secondary organic aerosol from (OH)-O-center dot initialed oxidation reaction of styrene in the presence of O-2/NO
Theoretical model on the formation possibility of secondary organic aerosol from (OH)-O-center dot initialed oxidation reaction of styrene in the presence of O-2/NO
复制标题
O-2/NO存在下苯乙烯(OH)-O-中心点起始氧化反应形成二次有机气溶胶可能性的理论模型
DOI：
10.1016/j.atmosenv.2014.10.042
复制
发表时间：
2015
影响因子：
5
通讯作者：
An Taicheng
中科院分区：
文献类型：
--
作者：
Wang Honghong;Ji Yuemeng;Gao Yanpeng;Li Guiying;An Taicheng
了解自由基dotOH氧化反应对于理解大气污染动力学和制定应对污染物问题的可能策略至关重要。本研究使用了一种基于理论的方法来模拟二次有机气溶胶（SOA）的形成机制，从苯乙烯自由基dotOH氧化反应中存在的O2/NO。作为一个比较措施，在没有NO（代表一个无污染的环境）的机制也进行了研究。结果表明，自由基dotOH对苯乙烯的初始进攻有两种方式：OH-加成和H-夺取。OH-脂肪族加成途径容易发生;在给定的大气条件下，H-提取途径可以忽略。发现IMaddβ（C6 H5 CHCH 2 OH）是主要的中间体，在O2存在下可转化为过氧自由基。在无NO气氛中，过氧自由基分解为循环自由基dotOH和醛类。在NO污染的大气中，它可以被降解为有机硝酸盐（RO-NO2），这在SOA的产生中起着重要作用。此外，计算出广州市大气颗粒物中有机硝酸盐的含量在2.4%~ 6.3%之间，有机硝酸盐可能是大气颗粒物中有机物的重要组成部分。采用正则变分过渡态理论计算的动力学数据表明，在NO污染/未污染大气中，苯乙烯-dotOH自由基氧化反应在0-12 km的高度范围内容易发生.特别是，在高NO污染的大气中，过氧自由基的寿命为10−3s，表明苯乙烯自由基dotOH氧化反应可以显著促进NO污染大气中SOA的形成。目前的研究结果为挥发性有机化合物（VOC）氧化反应形成SOA提供了可能的方法，并有助于评估区域空气质量，特别是在高NO污染的大气中。
Understandingradical dotOH oxidation reaction is vital in understanding atmospheric pollution dynamics, and developing possible strategies for countering pollutant problems. This study used a theory-based approach to model the formation mechanisms of secondary organic aerosol (SOA) from styrene-radical dotOH oxidation reactions in the presence of O2/NO. As a comparative measure, the mechanisms in the absence of NO (representing a pollution-free environment) were also investigated. The results showed that styrene can be initially attacked byradical dotOH in two ways: OH-addition and H-abstraction. The OH-aliphatic-addition pathway occurs easily; the H-abstraction pathway may be ignored given atmospheric conditions. It was found that IMaddβ (C6H5CHCH2OH) was the main intermediate, and could be transformed to a peroxyl radical in the presence of O2. In the NO-free atmosphere, the peroxyl radical was decomposed to recycling-radical dotOH and aldehydes. In the NO-polluted atmosphere, it could be degraded to organic nitrate (RO-NO2) which plays an important role in the production of SOA. Besides, the percent of organic nitrate in the particulate phase was calculated within the range of 2.4%–6.3% in Guangzhou city, and organic nitrates may constitute an important fraction of the total organic aerosol. The kinetic data calculated using canonical variational transition state theory with the small-curvature tunneling correction showed that, in the NO-polluted/unpolluted atmospheres, the styrene-radical dotOH oxidation reaction easily occurred across an altitude range of 0–12 km. Especially, peroxyl radical lifetime was 10−3s in the high NO-polluted atmosphere, indicating that the styrene-radical dotOH oxidation reaction could significantly contribute to SOA formation in the NO-polluted atmosphere. The current results informed possible approaches for forming SOA from volatile organic compound (VOC) oxidation reactions, and could help evaluate regional air quality, especially in high NO-polluted atmospheres.