Construction of self-cleaning g-C3N4/Bi2MoO6/PVDF membrane and coupling with photo-Fenton-like reaction for sustainable removal of antibiotics in wastewater

Abstract

Constructing a photocatalytic membrane and photo-Fenton reaction coupling system is a novel strategy to enhance the photocatalytic activity of the membrane and eliminate the problem of membrane contamination. Herein, a g-C₃N₄/Bi₂MoO₆/PVDF photocatalytic membrane was prepared using a tannic acid-assisted in-situ deposition method. The membrane was characterized by three advantages of photocatalytic, self-cleaning, and antibacterial properties. Under the photo-Fenton-like conditions, the membrane had superior photodegradation efficiency of 90.7% for tetracycline, one of the main antibiotic contaminants in the China's aquatic system. Moreover, the membrane had excellent photo-Fenton self-cleaning ability, its flux recovery rate was up to 96%-98% after the self-cleaning process. Photoluminescence spectra, diffuse UV-visible spectrum, transient photocurrent responses, and electrochemical AC impedance spectrum results show that the heterojunction structure formed by g-C₃N₄ and Bi₂MoO₆ could improve the separation efficiency of photogenerated electrons-hole pairs. Electron spin resonance spectroscopy confirmed the photo-electrons facilitated the formation of hydroxyl radical (·OH) in the existence of H₂O₂, which enhanced tetracycline degradation. Moreover, the superior photo-Fenton self-cleaning performance, which mainly relied on the active free radicals produced by the photo-Fenton-like membrane to remove dirt on the membrane surface or in the membrane pore channel. Our results may shed new light on the development of promising photocatalytic membrane systems by coupling with photo-Fenton-like processes, and facilitate their applications for wastewater treatment.

Keywords: Antibacterial; G-C(3)N(4)/Bi(2)MoO(6); Membrane; Photo-fenton; Photocatalytic; Self-cleaning.