羟基自由基与游离氧原子竞争作用下的光氧化降解苯反应路径  

Study on the reaction path of photo-oxidative degradation of benzene under the competition of hydroxyl radicals and free oxygen atoms

作　　者：李智 尹亮 段锋 张丽徽 LI Zhi;YIN Liang;DUAN Feng;ZHANG Lihui(School of Energy and Environment,Anhui University of Technology,Maanshan,243002,China;China Tobacco Hubei Industrial Co.,Ltd.,Wuhan,430048,China)

机构地区：[1]安徽工业大学能源与环境学院,马鞍山243002 [2]湖北中烟工业有限公司,武汉430048

出　　处：《环境化学》2023年第10期3590-3599,共10页Environmental Chemistry

基　　金：安徽省高校学科(专业)拔尖人才学术资助重点项目(gxyqZD2021108);中国博士后科学基金(2020M680614)资助.

摘　　要：本文实验研究了相对湿度对光氧化降解苯的直接转化效率、矿化率以及对应的尾气成分的影响,并利用量子化学DFT(Density functional theory)的方法讨论了不同相对湿度条件下羟基自由基与游离氧原子竞争作用下的光氧化降解苯反应路径.结果表明,苯的直接转化效率随着体系相对湿度的增加出现先升高后降低的趋势,相对湿度为50%时直接转化效率最高,为82%,矿化率随相对湿度的增加显著降低,最低可达到2%,且不同相对湿度条件下的尾气成分差异较大.在相对湿度为40%的条件下,苯分子的氧化降解路径主要是1,2-环己二醇氧化为1,2-环己二酮,此时最大的反应能垒值为15.3 kcal·mol^(−1),有利于提高苯降解的矿化效果,生成了P10苯乙酮和P11苯甲醛等分子质量更大的有机物;随着相对湿度由50%提高到80%,最大的反应能垒值由48.1 kcal·mol^(−1)降低到22.9 kcal·mol^(−1),此时苯的氧化路径由1,4-环己二醇氧化为1,4-环己二酮与1,2-环己二醇氧化为1,2-环己二酮共同决定,羟基自由基的引入大大降低了1,4-环己二醇与1,2-环己二醇氧化的难度,苯的矿化率和直接转化率急剧降低.确定最佳的相对湿度需要综合分析直接转化效率、矿化率以及尾气成分.The effects of relative humidity on the direct conversion efficiency,mineralization rate and components of waste gas from benzene photooxidation degradation were studied.Quantum chemical DFT method was used to analyze the reaction path of benzene photooxidation degradation under the competition of hydroxyl radical and oxygen atoms at different relative humidity.The results showed that the direct conversion efficiency of benzene increased first and then decreased with increasing relative humidity.The maximum direct conversion efficiency was 82%appearing at relative humidity of 50%.The mineralization rate decreased significantly at higher relative humidity,and the smallest value is 2%.The components of waste gas varied much at different relative humidity.At relative humidity of 40%,the oxidative degradation path of benzene was determined by oxidation of 1,2-cyclohexanediol to 1,2-cyclohexanedione,and the maximum reaction energy barrier is 15.3 kcal·mol^(−1),which is beneficial to improving the mineralization effect and generating some organic compounds with higher molecular weight such as P10 acetophenone and P11 benzaldehyde;As the relative humidity increased from 50%to 80%,the maximum reaction energy barrier decreased from 48.1 kcal·mol^(−1)to 22.9 kcal·mol^(−1).At this time,oxidative degradation path of benzene was determined by oxidation of 1,4-cyclohexanediol to 1,4-cyclohexanedione and oxidation of 1,2-cyclohexanediol to 1,2-cyclohexanedione.The introduction of hydroxyl radicals greatly decreased the oxidation difficulty of 1,4-cyclohexanediol and 1,2-cyclohexanediol,resulting in sharply decreasing mineralization rate and direct conversion efficiency.To determine the optimal relative humidity,it is necessary to comprehensively analyze the direct conversion efficiency,mineralization rate,and components of waste gas.

关 键 词：光氧化 苯 相对湿度 量子化学 DFT 

分 类 号：X701[环境科学与工程—环境工程]