摘要
基于硫酸根自由基(SO_4^(·-))的高级氧化技术被广泛应用于土壤和地下水污染修复.本研究系统地考察了三氯生在热活化过硫酸盐高级氧化过程中的动力学、中间产物和降解途径.结果表明,提高反应温度或增加过硫酸盐的浓度,可加快三氯生的降解.三氯生的降解符合假一级反应动力学规律,反应活化能(Ea)为142 k J·mol^(-1).水中的腐殖酸显著抑制了三氯生的降解,而氯离子(Cl^-)对三氯生降解的影响比较复杂.当Cl^-浓度为5μmol·L^(-1)时,三氯生的降解受到了轻微的促进;但是当Cl^-的浓度增加至10μmol·L^(-1)甚至更高时,三氯生的降解反而受到了抑制.通过质谱分析发现三氯生降解过程中生成了4-氯-邻苯二酚、2,4-二氯苯酚和2-氯-5-(2,4-二氯-6-羟基苯氧基)-1,4-苯醌等6种主要中间产物,并由此推测醚键的断裂和酚环羟基化是三氯生的可能降解途径.本研究为基于SO_4^(·-)的高级氧化技术去除水中三氯生的应用可行性提供了依据.
Sulfate radical（ SO4^·--based advanced oxidation technologies（ SR-AOPs） are widely used for remediation of contaminated groundwater and soils. This study investigated the reaction kinetics,products,and transformation pathways of triclosan,a widely used antimicrobial agent,during its degradation by heat activated persulfate oxidation. Experimental results revealed that increasing temperature or initial persulfate concentration significantly enhanced the degradation of triclosan. The reaction could be fitted in the pseudo-first-order kinetic model and the activation energy（ Ea） was determined to be 142 k J·mol^-1. The presence of humic acid markedly inhibited triclosan degradation,whereas chloride（ Cl^-） showed a more complicated effect. Triclosan degradation was slightly accelerated in the presence of 5 μmol·L^-1 Cl^-,however,a higher concentration of Cl^-（ e. g.,10 μmol·L^-1） showed an inhibitory effect. Using liquid chromatography-mass spectrometry,a total of six transformation products,including 4-chlorocatechol,2,4-dichlorophenol,and 2-chloro-5-（ 2,4-dichloro-6-hydroxyphenoxy）-1,4-benzoquinone,were identified. Accordingly,the cleavage of the ether bond and hydroxylation of the phenol ring were proposed as the principal pathways of triclosan degradation upon reaction with SO4^·- The findings of this study can be used to evaluate the feasibility of decontamination of triclosan by SR-AOPs.
作者
蒋梦迪
张清越
季跃飞
陆隽鹤
JIANG Meng-di, ZHANG Qing-yue, JI Yue-fei, LU Jun-he(College of Resources ＆ Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, Chin)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2018年第4期1661-1667,共7页
Environmental Science
基金
南京农业大学大学生实践创新训练计划项目(1613A06)
江苏省优势学科项目
关键词
三氯生
硫酸根自由基
热活化
动力学
中间产物
triclosan
sulfate radical
heat activation
kinetics
transformation products
