Fabrication, characterization, and performance evaluation of Bi2WO6/TiO2/Fe3O4 photocatalyst responding to visible light for enhancing bisphenol A degradation

Abstract

A novel magnetic Bi₂WO₆/TiO₂/Fe₃O₄ photocatalyst was synthesized by a hydrothermal approach. The pattern, structure, elemental composition, light-absorbing properties, and magnetism of Bi₂WO₆/TiO₂/Fe₃O₄ were characterized and analyzed. The performance, influencing factors, and mechanism of Bi₂WO₆/TiO₂/Fe₃O₄ towards bisphenol A (BPA) degradation were investigated and deduced. BPA removal up to 95% was achieved with the addition of 1.25 g/L Bi/Ti/Fe2 (molar ratio of Bi₂WO₆:TiO₂:Fe₃O₄ = 2:1:0.17) in the solution containing 10 mg/L BPA at pH 5.6. The performance of Bi/Ti/Fe2 was stable for five cycles at least after extracted from the reacted solution by magnet. Photoexcited h⁺, •OH, and •O₂^- formed in the reaction mainly contributed to BPA degradation. The Bi/Ti/Fe2 composite was composed of a three-layer petal structure from outside to inside to be Bi₂WO₆, TiO₂, and Fe₃O₄. This structure was conducive in forming a heterojunction between TiO₂ and Bi₂WO₆, inhibiting the merging of photoexcited e^- and h⁺, and improving the photocatalytic efficiency.

Keywords: Bi2WO6/TiO2/Fe3O4 composite; Bisphenol A; Free radicals oxidation; Magnetic photocatalyst; Photogenerated holes.