State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, PR China; 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.
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; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
Chemosphere. 2018 Mar;195:673-682. doi: 10.1016/j.chemosphere.2017.12.113. Epub 2017 Dec 19.
Organic chloramines can interfere with the measurement of effective combined chlorine in chlorinated water and are potential intermediate products of highly toxic disinfection by-products (DBPs). In order to know more about the degradation and transformation of organic chloramines, a typical organic chloramine precursor creatinine was selected for investigation and a corresponding individual organic chloramine chlorocreatinine was prepared in this study. The preparation condition of chlorocreatinine by chlorination was established as chlorine/creatinine = 1 M/M, reaction time = 2 h and pH = 7.0. Then the degradation kinetics of chlorocreatinine during further chlorination was studied, and a second-order rate constant of 1.16 (±0.14) M s was obtained at pH 7.0. Solution pH significantly influenced the degradation rate, and the elementary rate constants of chlorocreatinine with HOCl+H, HOCl, OCl and chlorocreatinine with OCl were calculated as 2.43 (±1.55) × 10 M s, 1.05 (±0.09) M s, 2.86 (±0.30) M s and 3.09 (±0.24) M s, respectively. Besides, it was found that chlorocreatinine could be further converted into several C-DBPs (chloroform and trichloroacetone) and N-DBPs (dichloroacetonitrile (DCAN) and trichloronitromethane (TCNM)) during chlorination. The total yield of DBPs increased obviously with increasing pH, especially for TCNM. In addition, the presence of humic acid in creatinine solution could increase the formation of DCAN obviously during chlorination. Based on the UPLC-Q-TOF-MS analysis, the conversion pathways of chlorocreatinine were proposed. Several kinds of intermediate products were also identified as organic chloramines and some of them could even exist stably during the further chlorination.
有机氯胺会干扰氯消毒水中有效余氯的测定，而且是潜在的剧毒消毒副产物（DBPs）的中间产物。为了更深入地了解有机氯胺的降解和转化，本研究选择了一种典型的有机氯胺前体肌酐，并制备了相应的单一有机氯胺氯肌酐。通过氯化制备氯肌酐的条件为氯/肌酐=1 M/M，反应时间=2 小时，pH=7.0。然后研究了进一步氯化过程中氯肌酐的降解动力学，在 pH 7.0 时得到了 1.16（±0.14）M s 的二级反应速率常数。溶液 pH 值显著影响降解速率，计算出 HOCl+H、HOCl、OCl 和氯肌酐与 OCl 的基本速率常数分别为 2.43（±1.55）×10 M s、1.05（±0.09）M s、2.86（±0.30）M s 和 3.09（±0.24）M s。此外，研究发现氯肌酐在氯化过程中可进一步转化为几种 C-DBPs（三氯甲烷和三氯丙酮）和 N-DBPs（二氯乙腈（DCAN）和三氯硝基甲烷（TCNM））。随着 pH 值的增加，DBPs 的总生成量明显增加，特别是 TCNM。此外，腐殖酸在肌酐溶液中的存在会显著增加 DCAN 在氯化过程中的生成量。基于 UPLC-Q-TOF-MS 分析，提出了氯肌酐的转化途径。还鉴定出几种中间体为有机氯胺，其中一些甚至在进一步氯化过程中能稳定存在。
