Construction of a Bi2WO6/BiVO4 photocatalytic system for efficient visible light degradation of tetracycline drugs

Abstract

A Bi₂WO₆/BiVO₄ composite photocatalytic material was synthesized by the hydrothermal method, and achieved the effective degradation of oxytetracycline (OTC) and tetracycline (TC) under visible light. The compositions, structures, chemical states and optoelectronic properties of Bi₂WO₆, BiVO₄ and Bi₂WO₆/BiVO₄ composites were characterized by systematic characterization. The results show that the existence of the heterojunction interface facilitates the separation of photogenerated carriers. Compared with the pure catalyst of Bi₂WO₆ and BiVO₄, the Bi₂WO₆/BiVO₄ composite material significantly improves the degradation efficiency of OTC and TC. The degradation rate is 6.22 and 3.02 times higher than that of Bi₂WO₆ and BiVO₄, respectively. Through the free radical quenching experiments, it is known that photogenerated holes (h⁺) and superoxide anion free radicals (·O₂⁻) are the main active substances in the degradation of OTC. By analyzing the process of photocatalytic degradation of OTC, there are mainly six intermediates during the process. Their possible degradation pathways are also inferred in this paper.