Preparation of Ag/Bi₂WO₆ and Its Photocatalytic Degradation Performance in Medical Wastewater

Abstract

Ag/Bi₂WO₆ photocatalyst was synthesized via a chemical deposition method. The structural and physicochemical properties of the as-prepared samples were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and photoluminescence (PL) spectroscopy. The photocatalytic performance of the samples was evaluated by degrading ofloxacin-containing medical wastewater. Results indicated that the Ag/Bi₂WO₆ composites exhibited a larger specific surface area, broader spectral response range, and higher separation efficiency of photogenerated electron-hole pairs compared to pure Bi₂WO₆. These properties contributed to the enhanced photocatalytic activity of the Ag/Bi₂WO₆ composites. In the photocatalytic degradation of ofloxacin, the optimal sample (4%-Ag/Bi₂WO₆) achieved a degradation rate of 93.8% after 60 minutes of light irradiation, with a first-order reaction rate constant of 0.0440 min⁻¹, which was 5.5 times higher than that of pure Bi₂WO₆. Cyclic degradation experiments demonstrated the excellent stability of the Ag/Bi₂WO₆ composite. Radical quenching experiments confirmed that ·OH and ·O₂⁻ were the primary active species responsible for the photocatalytic degradation of ofloxacin.