title: Enhancement of bromate formation by pH depression during ozonation of bromide-containing water in the presence of hydroxylamine.
abstract: This work investigated the fate of bromate formation during ozonation in the presence of hydroxylamine (HA). Results indicated that pH depression, as a commonly feasible control strategy for bromate formation during ozonation, unexpectedly enhanced the bromate formation during ozonation in the presence of HA. A dramatically high level of bromate was observed at acidic pH in the ozone/HA process. The scavenging experiments demonstrated the essential role of OH produced in the reaction of ozone with HA in bromate formation. In the process, OH mainly oxidizes bromide to Br, which is further oxidized by ozone and eventually converts to bromate. Further investigations suggested that the unexpected enhancement on bromate formation by pH depression can be mainly ascribed to the pH-dependent ozone decay, OH exposures and formation rate of Br. As pH decreased from 7 to 5, the reduced OH scavenging capacity of HA led to higher OH exposures, which contributed to the enhancement of bromate formation. As pH decreased from 5 to 3, the enhanced formation rate of Br largely augmented the formation of bromate. In addition, the ozone decay slowed down by pH depression provided more available ozone for the oxidation of the formed Br to bromate. The enhanced effect of pH depression on bromate formation was still observed in the real water samples in the ozone/HA process. Accordingly, pH depression might be avoided to control the bromate formation during ozonation in the presence of HA.
authors.affiliation: Shenzhen Key Laboratory of Water Resource Application and Environmental Pollution Control, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China.
authors.forename: Jingxin
authors.initials: J
authors.lastname: Yang
authors.affiliation: Shenzhen Key Laboratory of Water Resource Application and Environmental Pollution Control, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China. Electronic address: liji99@foxmail.com.
authors.forename: Ji
authors.initials: J
authors.lastname: Li
authors.affiliation: Shenzhen Key Laboratory of Water Resource Application and Environmental Pollution Control, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China.
authors.forename: Wenyi
authors.initials: W
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China. Electronic address: majun@hit.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Shenzhen Key Laboratory of Water Resource Application and Environmental Pollution Control, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China.
authors.forename: Jiayin
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Shenzhen Key Laboratory of Water Resource Application and Environmental Pollution Control, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Gu
authors.affiliation: Shenzhen Key Laboratory of Water Resource Application and Environmental Pollution Control, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China.
authors.forename: Wanying
authors.initials: W
authors.lastname: Xie
authors.affiliation: Shenzhen Key Laboratory of Water Resource Application and Environmental Pollution Control, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Cang
mesh_terms: D001959:Bromates; D001965:Bromides; D003863:Depression; D006863:Hydrogen-Ion Concentration; D019811:Hydroxylamine; D006898:Hydroxylamines; D010126:Ozone; D014867:Water; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D001959:Bromates; D001965:Bromides; D006898:Hydroxylamines; D014874:Water Pollutants, Chemical; D014867:Water; D019811:Hydroxylamine; D010126:Ozone
keywords: Bromate; Hydroxyl radical (()OH); Hydroxylamine; Ozone; pH depression