天冬氨酸氯化生成含氮消毒副产物连续反应动力学的建模

Modelling of Consecutive Reaction Kinetics for N-DBPs Formation Chlorinated by Aspartic Acid

饮用水中的有机物与消毒剂反应会产生消毒副产物(DBPs),其中,含氮消毒副产物(N-DBPs)相对于常规的DBPs具有更强的基因毒性和细胞毒性。为了有效确定N-DBPs的生成趋势及其稳定性,为实际生产有效控制N-DBPs提供参考,以天然水体中普遍存在的天冬氨酸(Asp)为N-DBPs前体物,研究了Asp氯化生成以二氯乙腈(DCAN)和二氯乙酰胺(DCAcAm)为代表的N-DBPs的经时变化规律,解析了N-DBPs的水解性能,探究了氯化含氮消毒副产物的连续反应机理,并建立连续反应动力学模型。研究表明,N-DBPs在生成的同时也会伴随着其水解,因此,DCAN、DCAcAm的浓度均会随着反应时间的增加而呈现先升高后降低的趋势,二者的水解常数分别为0.011、0.008 h^(-1),DCAN相对来说更不稳定。通过拟合,DCAN、DCAcAm出现最大质量浓度分别为125.4、33.03μg/L,对应时间分别为4.66、7.61 h,表明2种N-DBPs的生成和水解均为一级反应,且符合连续一级反应动力学,但生成的最大浓度及其对应时间有所差异。

Organic compounds in drinking water react with disinfectants to produce disinfection by-products(DBPs), in which nitrogenous disinfection by-products(N-DBPs) have stronger genotoxicity and cytotoxicity than conventional DBPs. In order to provide a reference for the effective control of N-DBPs in actual production, it is important to determine the generation trend and stability of N-DBPs. As a ubiquitous amino acid in natural water, aspartic acid(Asp) was used as the precursor of N-DBPs in this study. The effect of the reaction time of N-DBPs, which was represented by dichloroacetonitrile(DCAN) and dichloroacetamide(DCAcAm) in this study, generated by chlorination of Asp was studied. The hydrolytic properties of N-DBPs were analyzed, the consecutive reaction mechanism of chlorinated nitrogenous disinfection by-products was investigated and the kinetic model of consecutive reaction was established. Because the generation of N-DBPs was also accompanied by its hydrolysis, the results showed that the concentrations of DCAN and DCAcAm both increased firstly and then decreased with the increase of reaction time. Hydrolysis constants were 0.011 h;, 0.008 h^(-1), respectively, which indicated that DCAN was more unstable. Through data fitting, the maximum concentrations of DCAN and DCAcAm were 125.4 μg/L and 33.03 μg/L, and corresponding time were 4.66 h and 7.61 h, respectively. Results show that the generation and hydrolysis of N-DBPs are first-order reactions, and also conform to consecutive first-order reaction kinetics, but maximum concentration and corresponding time are different.