Photoreduction of Cr(VI) in water using BiVO4-Fe3O4 nano-photocatalyst under visible light irradiation.

The residuals of hexavalent chromium in the aquatic environment have raised much concern for water decontamination. In this study, BiVO4-Fe3O4 was synthesized using a solvothermal method and adopted as a photoreduction catalyst to removal of Cr(VI) in water under visible light irradiation. The physical and chemical properties of BiVO4-Fe3O4 were characterized by UV-vis-DRS, SEM, XRD, FTIR, and BET. The results demonstrated that the band gap for the obtained material is 1.74 eV with an average size of 15 nm and a specific surface area of 55.16 m2/g. A high photocatalytic performance was observed on the photoreduction of Cr(VI) and the removal efficiency was increased in the lower pH condition. The ascending catalyst dosages made the promotion effect, while the increase of Cr(VI) concentration contributed the inhibition for the reduction performance. The structural characteristics of the selected hole scavengers (ethanol, isopropanol, formic acid, citric acid, and oxalic acid) showed the various effects on the reactions due to the amounts of α-OH. For the optimal condition, 79.37% Cr(VI) was removed. Based on the excellent reusability of BiVO4-Fe3O4, this study demonstrated a potential method for the economic-friendly removal of high-valence metals with easier separation in the water.