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

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.