水体中三氯生与硫酸根自由基的反应动力学和机理  

Reaction kinetics and mechanism of triclosan with sulfate radical in aqueous solution

作　　者：朱梦钰 朱勇超 胡亚东 董林昌 朱承驻[1,2] ZHU Mengyu;ZHU Yongchao;HU Yadong;DONG Linchang;ZHU Chengzhu(School of Resources&Environmental Engineering,Hefei University of Technology,Hefei,230009,China;Institute of Atmospheric Environment&Pollution Control,Hefei University of Technology,Hefei,230009,China)

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

出　　处：《环境化学》2022年第12期3886-3892,共7页Environmental Chemistry

基　　金：国家自然科学基金(21876038)资助.

摘　　要：利用266 nm激光闪光光解瞬态吸收光谱技术探讨了水体中三氯生(TCS)与硫酸根自由基(SO_(4)^(·−))的光化学反应机制,考察了其反应瞬态物种的生长和衰减动力学,并利用气相色谱质谱联用(GC-MS)技术分析了稳态光解产物.结果表明,SO_(4)^(·−)与TCS反应的总速率常速为(3.39±0.22)×10^(9) L∙mol^(−1)∙s^(−1),其主要途径是SO_(4)^(·−)亲电加成攻击TCS的芳环形成TCS-SO_(4)^(·−)加合物(TCS-SO_(4)^(·−)adduct),二级反应速率常数为(2.71±0.24)×10^(9) L∙mol^(−1)∙s^(−1).并且TCS-SO_(4)^(·−)adduct可与溶解氧发生反应,二级速率常数为(1.40±0.14)×10^(8) L∙mol^(−1)∙s^(−1).TCS与SO_(4)^(·−)的转化产物主要有2-(2,4-二氯苯氧基)苯酚和2-氯-5(2,4-二氯-3,5,6-三羟基苯氧基)-1,4-苯醌等.从产物分析可知,TCS与SO_(4)^(·−)的反应途径主要有两种,一种是SO_(4)^(·−)直接攻击TCS上的氯取代基并且脱氯成分子量更小的苯酚.另一种是SO_(4)^(·−)通过亲电加成生成TCS-SO_(4)^(·−)adduct,接着生成相应的酚和醌,最后被SO_(4)^(·−)氧化生成羟基化产物.The photochemical reaction mechanism of triclosan(TCS)and sulfate radical(SO_(4)^(·−))in water was studied by using 266 nm laser flash photolysis transient absorption spectroscopy techniques.Its growth and decay kinetics of the reaction transient species were systematically investigated.The reaction products were analyzed by gas chromatography mass spectrometry(GCMS).The results revealed that the overall reaction rate constant of SO_(4)^(·−)with TCS was(3.39±0.22)×10^(9) L∙mol^(−1)∙s^(−1),while the main pathway was SO_(4)^(·−)attacked the aromatic ring of TCS through electrophilic addition and formed TCS-SO_(4)^(·−)adduct,the second-order reaction rate constant was(2.71±0.24)×10^(9) L∙mol^(−1)∙s^(−1).In addition,TCS-SO_(4)·^(−)adduct could react with dissolved oxygen,and the second-order rate constant was(1.40±0.14)×10^(8) L∙mol^(−1)∙s^(−1).The transformation products of TCS and SO_(4)^(·−)mainly included 2-(2,4-dichlorophenoxy)phenol and 2-chloro-5(2,4-dichloro-3,5,6-trihydroxy-phenoxy)-1,4-benzoquinone,etc.From the analysis of products,there were two main reaction pathways between TCS and SO_(4)^(·−).One was that SO_(4)^(·−)directly attacked the chlorines in TCS to generate phenols with smaller molecular weight via dechlorination.The other option was SO_(4)^(·−)created TCS-SO_(4)^(·−)adduct through electrophilic addition,then generated corresponding phenol and quinone,which were finally oxidized by SO_(4)^(·−)to generate hydroxylated products.

关 键 词：三氯生 硫酸根自由基 激光闪光光解 反应动力学 

分 类 号：X52[环境科学与工程—环境工程]