title: Pathway fraction of bromate formation during O₃ and O₃/H₂O₂ processes in drinking water treatment.
abstract: Ozone process has been widely used for drinking water treatment recently. In the oxidation process, bromate is formed by three pathways, i.e., the direct pathway, the direct-indirect pathway and the indirect-direct pathway. This study developed a method to calculate the percentage of these three pathways for bromate formation during O3 process and O3/H2O2 process. Two kinds of water, distilled water containing bromide (DW) and surface water from the Yellow River (SW) were selected as raw rater. The result showed that in natural water systems, the direct-indirect pathway was dominant for bromate formation during the oxidation process. When 3 mg L(-1) O3 was used as the only oxidant, nearly 26% of bromide ion was transferred into bromate in two kinds of water after 80 min. The dominant pathway in DW was the direct pathway (48.5%) and the direct-indirect pathway (46.5%), while that was the direct-indirect pathway (68.9%) in SW. When O3/H2O2 were used as oxidants, as the H2O2 dosage increased, the fractions of bromate formation by direct pathway and direct-indirect pathway decreased, while that by indirect-direct pathway increased. The conversion ratio from bromide to bromate first kept stable or increased, then decreased and reached its minimum when [H2O2]/[O3] ratio was 1.0 in DW and 1.5 in SW. Under this condition the indirect-direct pathway took the largest fraction of 70.7% in DW and 64.0% in SW, respectively.
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Shengqi
authors.initials: S
authors.lastname: Qi
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Mao
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Lv
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Sun
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Xiaomao
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: yanghw@mail.tsinghua.edu.cn.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Yang
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.
authors.forename: Yuefeng F
authors.initials: YF
authors.lastname: Xie
mesh_terms: D001959:Bromates / Q000032:analysis*; D001965:Bromides / Q000032:analysis; D060766:Drinking Water / Q000032:analysis*; D004784:Environmental Monitoring; D006812:Humic Substances / Q000032:analysis; D006861:Hydrogen Peroxide / Q000737:chemistry; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D001959:Bromates; D001965:Bromides; D060766:Drinking Water; D006812:Humic Substances; D014874:Water Pollutants, Chemical; D010126:Ozone; D006861:Hydrogen Peroxide
keywords: Bromate; Hydrogen peroxide; Hydroxyl radical; Ozone; Pathway fraction