State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Chemosphere. 2013 Nov;93(11):2662-8. doi: 10.1016/j.chemosphere.2013.08.035. Epub 2013 Sep 10.
The kinetics of chlorination of dinoseb and the corresponding formation of disinfection by-products (DBPs) were studied between pH 4 and 9 at room temperature (25±1°C). The reactivity shows a minimum at pH 9, a maximum at pH 4 and a medium at neutral conditions. pH profile of the apparent second-order rate constant of the reaction of dinoseb with chlorine was modeled considering the elementary reactions of HOCl with dinoseb species and an acid-catalyzed reaction. The predominant reactions at near neutral pH were the reactions of HOCl with the two species of dinoseb. The rate constants of 2.0 (±0.8)×10(4)M(-2)s(-1), 3.3 (±0.6) and 0.5 (±0.1)M(-1)s(-1) were determined for the acid-catalyzed reaction, HOCl reacted with dinoseb and dinoseb(-), respectively. The main degradation by-products of the dinoseb formed during chlorination have been separated and identified by GC-MS with liquid-liquid extraction sample pretreatment. Six volatile and semi-volatile DBPs were identified in the chlorination products, including chloroform (CF), monochloroacetone, chloropicrin (TCNM), 1,1-dichloro-2-methy-butane, 1,2-dichloro-2-methy-butane, 1-chloro-3-methy-pentanone. A proposed degradation pathway of dinoseb during chlorination was then given. TCNM and CF formation potential during chlorination of dinoseb reached as high as 0.077 and 0.097μMμM(-1) dinoseb under the traditional condition (pH=7 and Cl2/C=2). Their yields varied with Cl2/C, pH and time. The maximum yields of TCNM appeared at molar ratio as Cl2/C=1 and pH 3, while the maximum of CF appeared at molar ratio as Cl2/C=4 and pH 7. [TCNM]/[CF] decreased with reaction time and increased solution pH.
在室温（25±1°C）下，研究了敌草隆在 pH 值为 4 到 9 之间的氯化动力学及其相应的消毒副产物（DBP）的形成。反应活性在 pH 值为 9 时最小，在 pH 值为 4 时最大，在中性条件下处于中等水平。考虑到次氯酸与敌草隆物种的基本反应和酸催化反应，对反应的表观二级速率常数的 pH 值曲线进行了建模。在近中性 pH 值下，主要反应是次氯酸与敌草隆的两种物种的反应。确定了酸催化反应、次氯酸与敌草隆和敌草隆（-）的反应的速率常数分别为 2.0（±0.8）×10（4）M（-2）s（-1）、3.3（±0.6）和 0.5（±0.1）M（-1）s（-1）。通过 GC-MS 结合液液萃取样品预处理，分离并鉴定了氯化过程中形成的敌草隆的主要降解副产物。在氯化产物中鉴定出六种挥发性和半挥发性 DBP，包括三氯甲烷（CF）、一氯丙酮、氯仿（TCNM）、1,1-二氯-2-甲基丁烷、1,2-二氯-2-甲基丁烷、1-氯-3-甲基戊酮。然后给出了敌草隆在氯化过程中的降解途径。在传统条件（pH=7 和 Cl2/C=2）下，敌草隆氯化时 TCNM 和 CF 的形成潜能高达 0.077 和 0.097μMμM（-1）敌草隆。它们的产率随 Cl2/C、pH 和时间而变化。TCNM 的最大产率出现在 Cl2/C 摩尔比为 1 和 pH 值为 3 时，而 CF 的最大产率出现在 Cl2/C 摩尔比为 4 和 pH 值为 7 时。[TCNM]/[CF]随着反应时间的延长和溶液 pH 值的升高而降低。
