355 nm光照下液相中甲苯与亚硝酸的交叉反应  

Cross reaction of toluene with nitrous acid in aqueous phase initiated by irradiation of 355 nm UV light

作　　者：雷宇[1] 陆军[2] 马建中[1] 王涛[1] 彭书传[1] 朱承驻[1,3] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]合肥工业大学分析测试中心,合肥230009 [3]合肥工业大学大气环境与污染控制研究所,合肥230009

出　　处：《环境化学》2017年第8期1693-1699,共7页Environmental Chemistry

基　　金：国家自然科学基金(21177034)资助~~

摘　　要：利用激光闪光光解技术研究了在355 nm激光作用下甲苯与亚硝酸的交叉反应机理,考察了反应瞬态物种的生长和衰减行为,对产物进行了GC-MS分析.结果表明,HNO_2在355 nm的紫外光照下产生的OH自由基和甲苯有两种反应途径,其一是加成反应,甲苯与OH自由基反应生成CH_3C_6H_5-OH加合物,反应速率常数为(4.1±0.4)×10~9L·mol^(-1)·s^(-1),该反应途径在对流层大气中占主导地位;其二是发生在侧链甲基上的提氢反应,反应生成苄基自由基.有氧条件下,CH_3C_6H_5-OH可与O_2反应,氧化为CH_3C_6H_5-OHO_2,反应速率常数为(6.8±0.2)×10~8L·mol^(-1)·s^(-1).Reaction mechanism of aqueous solution of toluene with nitrous acid in the presence of O_2 and absence of O_2 were studied by laser flash photolysis. The main characteristic peaks in these transient absorbance spectra were assigned and the build-up/decay processes of several transient species were investigated. Results illustrated ·OH was produced in aqueous solution of nitrous acid exposed to 355 nm laser beam. There are two possible pathways of the reaction between ·OH and toluene. The first is radical adduct formation,especially the addition of ·OH to aromatic ring. The bimolecular rate constant was measured to be（ 4.1±0.4） ×109L·mol^-1·s^-1,and it was considered as a dominated way of the reaction between ·OH and toluene in troposphere system. In addition,·OH could also abstract a hydrogen atom from side chain methyl group to form benzyl radicals. The transient product CH_3C_6H_5-OH reacted with O_2 to form CH_3C_6H_5-OHO_2 with a rate constant of（ 6.8±0.2） ×10~8L·mol^-1·s^-1. The photo products were analyzed by GC/MS and the possible reaction pathways were discussed.

关 键 词：激光闪光光解 瞬态吸收光谱 亚硝酸 甲苯 OH自由基 大气液相 

分 类 号：X131.1[环境科学与工程—环境科学]