二氧化氯降解磺胺甲恶唑的反应机理研究  

The mechanism of sulfamethoxazole degraded by chlorine dioxide

作　　者：蔡永鑫 陈汉棱 赵思佳 李楠 黄俊杰 韦安磊[1,2] 马海霞 CAI Yongxin;CHEN Hanleng;ZHAO Sijia;LI Nan;HUANG Junjie;WEI Anlei;MA Haixia(College of Urban and Environmental Sciences,Northwest University,Xi’an,710127,China;Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity,College of Urban and Environmental Sciences,Northwest University,Xi’an,710127,China;School of Chemical Engineering,Northwest University,Xi’an,710127,China)

机构地区：[1]西北大学城市与环境学院,西安710127 [2]陕西省地表系统与环境承载力重点实验室,西安710127 [3]西北大学化工学院,西安710127

出　　处：《环境化学》2024年第10期3515-3526,共12页Environmental Chemistry

基　　金：国家自然科学基金(42277414);陕西省自然科学基金(2018JQ5151);陕西省教育厅专项科研计划项目(18JK0787)资助.

摘　　要：磺胺甲恶唑(SMX)作为新型污染物在水环境中广泛检出,现有水处理工艺难以降解去除,二氧化氯(ClO_(2))作为高效氧化剂和消毒剂能有效降解磺胺类抗生素.为探究ClO_(2)降解SMX的反应路径,本研究采用量子化学计算方法分析模拟ClO_(2)降解SMX的反应历程,结合反应产物的实验测定结果,确定二者反应的产物结构并提出反应路径.研究结果表明,ClO_(2)通过非离子化水解和单电子转移过程产生·OH并对SMX进行氧化降解,在SMX的异恶唑环和苯环上发生加成反应,其中,C21位点最易发生加成,势垒仅为5.1 kcal·mol^(−1);SMX的C3位点先发生加成反应,得到反应中间体,再进一步发生C(3)-N(11)键的断裂,两步反应的势垒分别为16.3 kcal·mol^(−1)和16.9 kcal·mol^(−1);C16位点发生的加成反应与S(13)-C(16)键的断裂存在协同效应,势垒为9.7 kcal·mol^(−1);SMX磺酰基S13位点与ClO_(2)发生取代反应,反应使N(11)-S(13)键断裂,势垒为18.9 kcal·mol^(−1).ClO_(2)降解SMX的主要产物为对氨基苯酚、对氨基苯磺酸、对氨基苯磺酰胺和5-甲基异恶唑-3-醇等.通过分析比对ClO_(2)降解SMX产物的质谱数据,验证了降解路径的合理性.本研究通过量子化学模拟结合实验结果分析反应机理及降解路径的方法合理可靠,可为ClO_(2)氧化降解复杂结构有机物提供科学依据.Sulfamethoxazole(SMX)has widely detected in the aqueous environment as an emerging contaminant and it is difficult to be removed by conventional water/wastewater treatment processes.Chlorine dioxide(ClO_(2))can effectively degrade sulfonamide antibiotics as an efficient oxidant and disinfectant.In order to investigate the reaction pathways of SMX reacting with ClO_(2),quantum chemical calculation and simulation were used to analyze the reaction pathways of SMX degraded by ClO_(2)in this research.Combined with experimental measurements of the reaction products between SMX and ClO_(2),reaction pathways were proposed and the product structures were determined.The results showed that ClO_(2) can generate·OH through the processes of nonionic hydrolysis and single electron transfer and then degrade SMX.Addition reactions occurred at the isoxazole ring and benzene ring of SMX and the most reactive site was C21 atom with a potential barrier of 5.1 kcal·mol^(−1).The reaction intermediate was obtained via the addition reaction of C3 site of SMX firstly,and then the C(3)-N(11)bond was broken.The potential barriers of the two reaction steps were 16.3 kcal·mol^(−1)and 16.9 kcal·mol^(−1),respectively.There was synergistic effect between addition reaction of the C16 and the breakage of the S(13)-C(16)bond,with a potential barrier of 9.7 kcal·mol^(−1).The substitution reaction occurred at the S13 site of the sulfonyl group,which induced the cleavage of the N(11)-S(13)bond with a potential barrier of 18.9 kcal·mol^(−1).p-aminophenol,p-aminobenzene sulfonic acid,p-aminobenzene sulfonamide and 5-methylisoxazol-3-ol were found to be the common products.The products of SMX reacting with ClO_(2) were determined and the degradation pathways were verified by comparing with the mass spectrometry data.The method of quantum chemistry simulation combined with experimental results to analyze the reaction mechanism and degradation path is reasonable and reliable,which can provide scientific basis for complex organic degraded b

关 键 词：二氧化氯 磺胺甲恶唑 量子化学 反应路径 

分 类 号：X-1[环境科学与工程] O6[理学—化学]