CuS/Bi₂O₃ composites activating PMS under visible light for efficient degradation of antibiotic tetracycline

CuS/Bi₂O₃ composite photocatalyst was prepared by calcination and in situ precipitation, and peroxymonosulfate (PMS) was applied to the degradation of tetracycline (TC) wastewater under visible light. The microscopic morphology, chemical composition, and optical properties of the composites were investigated by characterization means of XRD, FTIR, SEM, XPS, and UV-Vis DRS. The results showed that the introduction of CuS increased the specific surface area of Bi₂O₃ and increased the visible absorption boundary of Bi₂O₃ from 455 to 524 nm, which effectively inhibited the complexation of photogenerated electron-hole pairs. The experimental results showed that the introduction of PMS strengthened the removal of TC from the composites, and 95% of TC could be removed under visible light irradiation, and the reaction rate was 8.22 times higher than that of the unspiked PMS, indicating that the BC-15+vis/PMS catalytic system could degrade the pollutants efficiently. The radical capture experiments showed that several radicals, including ·OH, SO₄·^-, ·O₂^-, h⁺, and ¹O₂, were present in the catalytic system as the main active species to degrade TC, and the mechanism of photocatalytic activation of PMS by Z-type heterostructures of CuS/Bi₂O₃ composites was proposed. The present study showed that BC-15 has excellent degradation performance and stability, which provides new ideas for the treatment of antibiotic wastewater.