Highly active magnetic bismuth tungstate/magnetite composite under visible light irradiation in the presence of hydrogen peroxide

Abstract Bi 2 WO 6 /Fe 3 O 4 composites were synthesized using hydrothermal method and their photocatalytic activity to degrade rhodamine B (RhB) under visible light irradiation assisted with H 2 O 2 and underlying mechanisms were investigated. The composites were 3D flower-like microspheres constructed by 2D Bi 2 WO 6 nanosheets loaded with spherical Fe 3 O 4 nanoparticles. The composited photocatalysts could be easily harvested from the reaction solution by an external magnetic field. In the presence of H 2 O 2 , a large amount of hydroxyl radicals ( OHs) were produced by H 2 O 2 reacting with photogenerated electrons. Fe 3 O 4 not only promoted the separation of hole–electron pairs but also acted as a Fenton-like reagent, expediting the production of OH. Thus, the composites in the presence of H 2 O 2 displayed much higher photocatalytic efficiency to degrade RhB than pure Bi 2 WO 6 . 98% of RhB (initial concentration 10 mg/L) was degraded in 2 h visible irradiation and 60% of total organic carbon (TOC) was removed in 3 h by 0.5 g/L Bi 2 WO 6 /Fe 3 O 4 (5:1). The composite displayed high photodegradation efficiency at pH 3–9. Our study suggests that a visible light driven and highly active magnetic photocatalyst-Fenton coupling oxidation system may have potential application in water treatment and environmental cleaning.