Synthesis of Bi2WO6/ZnFe2O4 magnetic composite photocatalyst and degradation of tetracycline hydrochloride under visible light

Abstract

Enhanced visible light photocatalytic activity of Bi2WO6/ZnFe2O4 magnetic composite photocatalyst was synthesized by a two step facile solvothermal process. The as-prepared photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectra and electrochemical impedance spectroscopy. The TCH visible-light photocatalytic degradation and magnetic performance of Bi2WO6-based magnetic composite catalysts were also measured. Results showed that an appropriate combining of ZnFe2O4 improved the adsorption performance and photocatalytic activity of Bi2WO6 catalysts, and enhanced the magnetism, recovery rate and practical values of catalysts. Among them, BZn3 (combined with 0.15 wt% ZnFe2O4) exhibited the best photocatalytic activity for degradation ratio of TCH reaching 96.85% in 90 min. The TCH degradation over each composite catalyst within the first 0–60 min obeyed a first-order kinetic equation, the maximum of kinetic constant reached 0.03659 min−1 (BZn3). In comparison, after combining with ZnFe2O4, the specific surface area of BZn3 was slightly increased (66.53 m2/g) and the adsorption performance was changed. BZn3 had smaller impedance arc radii under both dark-state and visible-slight state, suggested that the photo-generated electron-cavity in BZn3 was efficiently separated and the transfer of photo-generated electrons at the interface of composite electrode/electrolyte was accelerated upon the visible-light excitation. Moreover, these composite catalysts were also highly stable and underlie the further application of Bi2WO6-based magnetic composite catalysts.