Efficient photocatalytic degradation of thiobencarb over BiVO4 driven by visible light: Parameter and reaction pathway investigations

In this study, BiVO4 powder with monoclinic structure was prepared and used as a visible-light catalyst for the photocatalytic degradation of thiobencarb (TBC). To the best of our knowledge, this is the first time reporting the photocatalytic degradation of TBC using BiVO4 as the catalyst. The as-prepared BiVO4 photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra (DRS). With the presence of both H2O2 and BiVO4 catalysts, TBC could be effectively degraded under visible-light irradiation. The degradation efficiency of TBC was 97% after 5 h in the photocatalytic process. Factors such as catalyst dosage, solution pH, hydrogen peroxide concentration and the presence of anions were found to influence the degradation rate. The BiVO4 powder displayed a good stability and maintained a high photocatalytic performance during three successive runs. To scrutinize the mechanistic details of the TBC photodegradation, the intermediates of the process were separated, identified, and characterized by solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) technique. The probable photodegradation pathways were proposed and discussed. The results would provide useful information for the research of thiocarbamate decomposition and the development of new applications of BiVO4.