The Synergistic Effect of Adsorption-Photocatalysis for Removal of Organic Pollutants on Mesoporous Cu₂V₂O₇/Cu₃V₂O₈/g-C₃N₄ Heterojunction

Abstract

Cu2V2O7/Cu3V2O8/g-C3N4 heterojunctions (CVCs) were prepared successfully by the reheating synthesis method. The thermal etching process increased the specific surface area. The formation of heterojunctions enhanced the visible light absorption and improved the separation efficiency of photoinduced charge carriers. Therefore, CVCs exhibited superior adsorption capacity and photocatalytic performance in comparison with pristine g-C3N4 (CN). CVC-2 (containing 2 wt% of Cu2V2O7/Cu3V2O8) possessed the best synergistic removal efficiency for removal of dyes and antibiotics, in which 96.2% of methylene blue (MB), 97.3% of rhodamine B (RhB), 83.0% of ciprofloxacin (CIP), 86.0% of tetracycline (TC) and 80.5% of oxytetracycline (OTC) were eliminated by the adsorption and photocatalysis synergistic effect under visible light irradiation. The pseudo first order rate constants of MB and RhB photocatalytic degradation on CVC-2 were 3 times and 10 times that of pristine CN. For photocatalytic degradation of CIP, TC and OTC, it was 3.6, 1.8 and 6.1 times that of CN. DRS, XPS VB and ESR results suggested that CVCs had the characteristics of a Z-scheme photocatalytic system. This study provides a reliable reference for the treatment of real wastewater by the adsorption and photocatalysis synergistic process.

Keywords

• Cu₂V₂O₇/Cu₃V₂O₈/g-C₃N₄ heterojunctions
• adsorption
• photocatalysis
• degradation
• Z-scheme