Chlorination of chlortoluron: kinetics, pathways and chloroform formation.
Chlorination of chlortoluron: kinetics, pathways and chloroform formation.
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DOI：
10.1016/j.chemosphere.2011.02.050
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发表时间：
2011-05
期刊：
影响因子：
8.8
通讯作者：
Bin Xu;Fu-xiang Tian;Chen-yan Hu;Yi-Li Lin;Shengji Xia;Rong Rong-Rong;Da-Peng Li
中科院分区：
文献类型：
--
作者：
Bin Xu;Fu-xiang Tian;Chen-yan Hu;Yi-Li Lin;Shengji Xia;Rong Rong-Rong;Da-Peng Li
在25±1°C、pH值为3-10的条件下，研究了绿麦隆的氯化作用。氯代动力学符合二级动力学模型，氯为一级动力学模型，绿麦隆为一级动力学模型。表观速率常数进行了测定，并发现在pH值为6时最小，在pH值为3时最大，在碱性条件下为中等。每个主要基元反应的速率常数（即，绿麦隆与HOCl的酸催化反应、绿麦隆与HOCl的反应和绿麦隆与OCl−的反应的动力学方程分别为3.12（± 0.10）× 107 M − 2 h −1、3.11（±0.39）× 102 M −1h− 1和3.06（±0.47）× 103 M −1h−1。采用吹扫捕集预处理、超高效液相色谱-电喷雾电离-质谱联用和气相色谱-电子捕获检测器对绿麦隆氯化过程中的主要副产物进行了定性分析。结果表明，消毒副产物主要有三氯甲烷、二氯乙腈、1，1-二氯丙酮、1，1，1-三氯丙酮、二氯硝基甲烷和三氯硝基甲烷。提出了绿麦隆氯化降解的途径。在绿麦隆氯化过程中产生高浓度的CF，在溶液的中性附近的pH值范围内的CF产量最大。
Chlortoluron chlorination is studied in the pH range of 3–10 at 25±1°C. The chlorination kinetics can be well described by a second-order kinetics model, first-order in chlorine and first-order in chlortoluron. The apparent rate constants were determined and found to be minimum at pH 6, maximum at pH 3 and medium at alkaline conditions. The rate constant of each predominant elementary reactions (i.e., the acid-catalyzed reaction of chlortoluron with HOCl, the reaction of chlortoluron with HOCl and the reaction of chlortoluron with OCl−) was calculated as 3.12 (± 0.10)×107M−2h−1, 3.11 (±0.39)×102M−1h−1and 3.06 (±0.47)×103M−1h−1, respectively. The main chlortoluron chlorination by-products were identified by gas chromatography–mass spectrometry (GC–MS) with purge-and-trap pretreatment, ultra-performance liquid chromatography–electrospray ionization-MS and GC-electron capture detector. Six volatile disinfection by-products were identified including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone, dichloronitromethane and trichloronitromethane. Degradation pathways of chlortoluron chlorination were then proposed. High concentrations of CF were generated during chlortoluron chlorination, with maximum CF yield at circumneutral pH range in solution.