title: Aqueous arsenite removal by simultaneous ultraviolet photocatalytic oxidation-coagulation of titanium sulfate.
abstract: This study explored the efficacy and efficiency of a simultaneous UV-catalyzed oxidation-coagulation process of titanium sulfate (UV/Ti(SO4)2) for efficient removal of As(III) from water. It revealed that, As(III) could be oxidized to As(V) during the UV catalyzed coagulation of Ti(SO4)2 with highly efficient As(III) removal in the pH range 4-6. The UV catalyzed oxidation-coagulation showed surprisingly effective oxidation of As(III) to As(V) within a short time. XPS indicated that 84.7% of arsenic on the coagulated precipitate was in the oxidized form of As(V) after the UV/Ti(SO4)2 treatment of As(III) aqueous solutions at pH 5. Arsenic remaining in solution at high pH was in the oxidized form As(V). Removal efficiencies of As(III) were investigated as a function of pH, Ti(SO4)2 dosage, initial As(III) concentration and irradiation energy. As(III) could almost completely be removed (>99%) by the photocatalytic oxidation-coagulation process with a moderate dose of Ti(SO4)2 in the pH range 4-6 at an initial arsenic concentration of 200 μg/L. The mechanisms of the photocatalytic coagulation oxidation of Ti(SO4)2 are similar to those of UV/crystalline TiO2 particles, involving the formation and reactions of the hydroxyl radical OH and superoxide HO2/O2(-).
authors.affiliation: Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi'an University of Architecture and Technology, China.
authors.forename: Yuxia
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi'an University of Architecture and Technology, China; Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes Campus, South Australia, Australia. Electronic address: jinmingduan@xauat.edu.cn.
authors.forename: Jinming
authors.initials: J
authors.lastname: Duan
authors.affiliation: Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi'an University of Architecture and Technology, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes Campus, South Australia, Australia.
authors.forename: Simon
authors.initials: S
authors.lastname: Beecham
authors.affiliation: Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes Campus, South Australia, Australia.
authors.forename: Dennis
authors.initials: D
authors.lastname: Mulcahy
keywords: Arsenite removal; Coagulation; Photocatalytic oxidation; Titanium salts