title: Formation of bromate during ferrate(VI) oxidation of bromide in water.
abstract: Ferrate (VI) is traditionally recognized as a safe oxidant without production of disinfection byproducts (DBPs). However, here we detected probable carcinogenic bromate (BrO3(-)) during ferrate(VI) oxidation of bromide (Br(-))-containing water, and evaluated the effects of pH, ferrate(VI) dose, initial Br(-) concentration, and co-existing anions on the BrO3(-) formation. BrO3(-) was produced at a moderately-weakly acidic pH condition and in the absence of phosphate that was commonly applied as a buffer and stabilizing agent in previous ferrate(VI) studies. At pH 5.0, the produced BrO3(-) was increased from 12.5 to 273.8 μg/L with the increasing initial Br(-) concentration from 200 to 1000 μg/L at 10 mg/L Fe(VI), corresponding to an increase in the molar conversion ([BrO3(-)]/initial [Br(-)]) from 2.3% to 10.3%, in a bicarbonate-buffered solution. As pH increased to 7.0, the BrO3(-) concentration gradually dropped. The BrO3(-) production appeared to be associated with the oxidation by high valence iron species (i.e. Fe(VI), Fe(V) and Fe(IV)). Two key intermediate products (i.e. hypobromous acid/hypobromite (HOBr/OBr(-)) and hydrogen peroxide (H2O2)) relevant to the bromate formation were identified. The production of HOBr, a requisite intermediate for the ensuing bromate formation, was indirectly validated through identification of bromine-containing trihalomethanes and haloacetic acids during ferrate oxidation in a natural water, though these bromo-organic DBPs produced were insignificant. Furthermore, the inhibition effects of various anions on the formation of BrO3(-) followed chloride < sulfate < silicate < phosphate. More H2O2 was detected at higher phosphate concentration. It could reduce HOBr to Br(-), thereby inhibiting the bromate formation.
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China; Department of Earth and Environmental Studies, Montclair State University, 1 Normal Ave., New Jersey, 07043, United States.
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.affiliation: Department of Earth and Environmental Studies, Montclair State University, 1 Normal Ave., New Jersey, 07043, United States. Electronic address: dengy@mail.montclair.edu.
authors.forename: Yang
authors.initials: Y
authors.lastname: Deng
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Earth and Environmental Studies, Montclair State University, 1 Normal Ave., New Jersey, 07043, United States; School of Civil Engineering and Architecture, Zhejiang University of Science and Technology, Hangzhou, 310023, China.
authors.forename: Yali
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Earth and Environmental Studies, Montclair State University, 1 Normal Ave., New Jersey, 07043, United States.
authors.forename: Nanzhu
authors.initials: N
authors.lastname: Li
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China.
authors.forename: Jizhi
authors.initials: J
authors.lastname: Zhou
mesh_terms: D001959:Bromates / Q000032:analysis / Q000737:chemistry*; D001965:Bromides / Q000032:analysis / Q000737:chemistry*; D004202:Disinfectants / Q000032:analysis / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D001959:Bromates; D001965:Bromides; D004202:Disinfectants; D016877:Oxidants; D014874:Water Pollutants, Chemical; D014867:Water; C017311:ferrate ion; D006861:Hydrogen Peroxide; D007501:Iron
keywords: Bromate(−); Bromide; Chemical oxidation; Disinfection byproducts; Ferrate(VI); Phosphate