Kinetics and mechanism for methiocarb degradation by chlorine dioxide in aqueous solution.
Kinetics and mechanism for methiocarb degradation by chlorine dioxide in aqueous solution.
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DOI：
10.1016/j.chemosphere.2010.02.015
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发表时间：
2010-04
期刊：
影响因子：
8.8
通讯作者：
Fang Tian;Z. Qiang;Chao Liu;Tao Zhang;B. Dong
中科院分区：
文献类型：
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作者：
Fang Tian;Z. Qiang;Chao Liu;Tao Zhang;B. Dong
在模拟水处理条件下研究了 ClO2 水溶液降解灭虫威 (MC) 的动力学和机理。实验结果表明，MC与ClO2之间的反应整体为二级反应，在23℃下，随着溶液pH值从6.0增加到9.1，速率常数从0.56迅速增加到4.5M−1s−1。在所研究的 7–35°C 温度范围内，活化能为 75kJmol−1。甲硫威亚砜 (MCX) 和甲硫威亚砜 (MCN) 被定量为 MC 降解的主要副产物。与许多硫醚氧化过程中相继形成亚砜和砜不同，这两种副产物是在 ClO2 降解 MC 过程中同时形成的。溶液pH值显着影响降解副产物的类型和数量。例如，在pH 6.5时，MCX和MCN随着反应的进行而积累，最终分别占MC降解的71%和28%；当 pH 值为 8.6 时，还发现了另外三种次要副产物。尽管ClO2可以有效氧化水中的MC，但毒性的显着增加给消费者带来了潜在风险。
The kinetics and mechanism for methiocarb (MC) degradation by aqueous ClO2were investigated under simulated water treatment conditions. Experimental results indicate that the reaction between MC and ClO2was of second-order overall, and the rate constant rapidly increased from 0.56 to 4.5M−1s−1as the solution pH increased from 6.0 to 9.1 at 23°C. The activation energy was determined to be 75kJmol−1in the studied temperature range of 7–35°C. Methiocarb sulfoxide (MCX) and methiocarb sulfone (MCN) were quantified to be the major byproducts from MC degradation. Unlike the sequential formation of sulfoxide and sulfone during the oxidation of many thioethers, the two byproducts were formed simultaneously during MC degradation by ClO2. The solution pH significantly affected the type and quantity of the degradation byproducts. For example, at pH 6.5 MCX and MCN accumulated as the reaction proceeded and finally accounted for 71% and 28% of MC degraded, respectively; while at pH 8.6 three more minor byproducts were identified. Though ClO2can effectively oxidize MC in water, the significant increase in toxicity raises a potential risk to consumers.