Ametryn degradation by aqueous chlorine: kinetics and reaction influences.
Ametryn degradation by aqueous chlorine: kinetics and reaction influences.
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DOI：
10.1016/j.jhazmat.2009.03.147
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发表时间：
2009-09
影响因子：
13.6
通讯作者：
Bin Xu;N. Gao;Hefa Cheng;Chen-yan Hu;Shengji Xia;Xiao-Feng Sun;Xuejiao Wang;Shaogui Yang
中科院分区：
文献类型：
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作者：
Bin Xu;N. Gao;Hefa Cheng;Chen-yan Hu;Shengji Xia;Xiao-Feng Sun;Xuejiao Wang;Shaogui Yang
在25°C的温度下，通过pH 4和10之间的氯化水溶液研究了除草剂莠灭净的化学氧化。发现扑草净与氯水溶液反应非常迅速。反应动力学可用二级动力学模型描述。在酸性和中性条件下，表观二级速率常数大于5× 102 M − 1 s − 1。反应在碱性条件下进行得慢得多。主要反应是HOCl与中性莠灭净和带电莠灭净的反应，速率常数分别为7.22× 102和1.58× 103 M − 1 s −1。在氯化过程中，随着溴素的加入，莠灭净的降解速率增加，随着氨的加入，莠灭净的降解速率降低。基于基元化学反应，建立了溴离子或氨离子存在下莠灭净氯化降解动力学模型。利用该模型，我们估算了HOBr与中性莠灭净和带电莠灭净反应的速率常数分别为9.07× 103和3.54× 106 M − 1 s −1。这些值比HOCl高10- 103倍，表明氯化过程中溴物种的存在可以显着加速莠灭净降解。
The chemical oxidation of the herbicide ametryn was investigated by aqueous chlorination between pH 4 and 10 at a temperature of 25°C. Ametryn was found to react very rapidly with aqueous chlorine. The reaction kinetics can be well described by a second-order kinetic model. The apparent second-order rate constants are greater than 5×102M−1s−1under acidic and neutral conditions. The reaction proceeds much more slowly under alkaline conditions. The predominant reactions were found to be the reactions of HOCl with neutral ametryn and the charged ametryn, with rate constants equal to 7.22×102and 1.58×103M−1s−1, respectively. The ametryn degradation rate increases with addition of bromide and decreases with addition of ammonia during the chlorination process. Based on elementary chemical reactions, a kinetic model of ametryn degradation by chlorination in the presence of bromide or ammonia ion was also developed. By employing this model, we estimate that the rate constants for the reactions of HOBr with neutral ametryn and charged ametryn were 9.07×103and 3.54×106M−1s−1, respectively. These values are 10- to 103-fold higher than those of HOCl, suggesting that the presence of bromine species during chlorination could significantly accelerate ametryn degradation.