State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China.
State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China.
Water Res. 2016 Mar 1;90:15-23. doi: 10.1016/j.watres.2015.11.068. Epub 2015 Dec 14.
In this work, the degradation of atrazine by the combination of UV and chlorine (UV/chlorine) due to the formation of radicals during chlorine photolysis was systematically investigated in terms of efficiency, factors that influence the degradation kinetics, as well as oxidation products. It was found that the degradation efficiency of atrazine was enhanced by UV/chlorine compared to UV or chlorine alone. The degradation efficiency of atrazine was favorable at a lower pH, but was inhibited in the presence of natural organic matters. Meanwhile, the initial chlorine dosage, alkalinity, and chloride barely influenced the degradation efficiency under neutral pH conditions. The degradation of atrazine by UV/chlorine was inhibited in real waters (i.e., surface water and ground water) compared to in deionized water but was still more effective than UV alone. The oxidation products of atrazine resulting from de-alkylation, dechlorination-hydroxylation, alkylic-hydroxylation, alkylic-oxidation, alkylic-hydroxylation-dehydration, deamination-hydroxylation, and dechlorination-hydrogenation in UV/chlorine process were detected, which were slightly different from those formed in UV/H2O2 (commonly used UV-based advanced oxidation process). Particularly, the yields of three primary transformation products (desethyl-atrazine (DEA), desisopropyl-atrazine (DIA), and desethyl-desisopropyl-atrazine (DEIA)) were comparatively quantified in these two processes. The different trend of them formed in UV/chlorine system (DEA:DIA≈4) compared to that formed in UV/H2O2 system (DEA:DIA≈1) could be ascribed to the different reaction reactivities and mechanisms between HO• and Cl• with atrazine.
在这项工作中，通过研究氯光解过程中自由基的形成，系统地研究了紫外线和氯气（UV/氯气）联合作用下莠去津的降解效率、影响降解动力学的因素以及氧化产物。结果表明，与单独使用 UV 或氯气相比，UV/氯气能提高莠去津的降解效率。在较低的 pH 值下，莠去津的降解效率较好，但在天然有机物存在的情况下受到抑制。同时，在中性 pH 条件下，初始氯剂量、碱度和氯离子对降解效率的影响较小。与去离子水相比，UV/氯气在实际水体（即地表水和地下水）中降解莠去津的效率受到抑制，但仍比单独使用 UV 更有效。在 UV/氯气过程中，莠去津通过脱烷基化、脱氯-羟基化、烷基-羟基化、烷基-氧化、烷基-羟基化-脱水、脱氨-羟基化和脱氯-氢化反应生成的莠去津氧化产物与在 UV/H2O2（常用的基于 UV 的高级氧化过程）中生成的产物略有不同。特别是，在这两种过程中比较定量地测定了三种主要转化产物（去乙基莠去津（DEA）、去异丙基莠去津（DIA）和去乙基-去异丙基莠去津（DEIA））的产率。与在 UV/H2O2 体系中形成的（DEA:DIA≈1）相比，在 UV/氯气体系中形成的（DEA:DIA≈4）的不同趋势可以归因于 HO•和 Cl•与莠去津之间的不同反应活性和机制。
