title: Degradation kinetics and N-Nitrosodimethylamine formation during monochloramination of chlortoluron.
abstract: The degradation of chlortoluron by monochloramination was investigated in the pH range of 4-9. The degradation kinetics can be well described by a second-order kinetic model, first-order in monochloramine (NH(2)Cl) and first-order in chlortoluron. NH(2)Cl was found not to be very reactive with chlortoluron, and the apparent rate constants in the studied conditions were 2.5-66.3M(-1)h(-1). The apparent rate constants were determined to be maximum at pH 6, minimum at pH 4 and medium at alkaline conditions. The main disinfection by-products (DBPs) formed after chlortoluron monochloramination were identified by ultra performance liquid chromatography-ESI-MS and GC-electron capture detector. N-Nitrosodimethylamine (NDMA) and 5 volatile chlorination DBPs including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone and trichloronitromethane were identified. The distributions of DBPs formed at different solution pH were quite distinct. Concentrations of NDMA and CF were high at pH 7-9, where NH(2)Cl was the main disinfectant in the solution. NDMA formation during chlortoluron monochloramination with the presence of nitrogenous salts increased in the order of nitrite<nitrate<ammonium for a given monochloramination and chlortoluron concentration.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze Aquatic Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. tjwenwu@tongji.edu.cn
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.forename: Cao
authors.initials: C
authors.lastname: Qin
authors.forename: Chen-Yan
authors.initials: CY
authors.lastname: Hu
authors.forename: Yi-Li
authors.initials: YL
authors.lastname: Lin
authors.forename: Sheng-Ji
authors.initials: SJ
authors.lastname: Xia
authors.forename: Qian
authors.initials: Q
authors.lastname: Xu
authors.forename: Seleli Andrew
authors.initials: SA
authors.lastname: Mwakagenda
authors.forename: Xiang-Yu
authors.initials: XY
authors.lastname: Bi
authors.forename: Nai-Yun
authors.initials: NY
authors.lastname: Gao
mesh_terms: D002700:Chloramines / Q000737:chemistry*; D004128:Dimethylnitrosamine / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D010671:Phenylurea Compounds / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D002700:Chloramines; D006540:Herbicides; D010671:Phenylurea Compounds; D014874:Water Pollutants, Chemical; C030816:chloramine; D004128:Dimethylnitrosamine; C007033:chlortoluron