A composite cathode membrane with CoFe2O4–rGO/PVDF on carbon fiber cloth: synthesis and performance in a photocatalysis-assisted MFC-MBR system

Abstract

In this study, a photocatalytic composite membrane (PCM) coated with CoFe₂O₄(–rGO) and polyvinylidene fluoride (PVDF) on a carbon fiber cloth was firstly prepared by inclusion of nanoparticles in a PVDF casting solution. The PCM with CoFe₂O₄(–rGO) functioned as the cathode membrane in a photocatalysis-assisted MFC-MBR system. Comparison tests with four types of MFe₂O₄ photo-catalysts (M = Ni, Fe, Co, Zn) in PCM indicated that CoFe₂O₄ had the highest oxygen reduction reaction (ORR) activity. Upon compositing with reduced graphene oxide (rGO), the CoFe₂O₄–rGO greatly improved the catalytic activity. Photocatalysis in the cathode greatly promoted both power generation and contaminant removal. The maximum power density of 942 mW m⁻³ (versus anode volume) was achieved using this PCM with CoFe₂O₄–rGO, under visible-light irradiation, and the removal of tetracycline hydrochloride antibiotics in a photocatalysis-assisted MFC-MBR system was higher than that without irradiation. By efficiently decomposing recalcitrant substances, the photocatalysis-assisted MFC-MBR system exhibits better and broader application potential in wastewater treatment than a conventional MFC-MBR system. The beneficial effects of nanoparticles on flux and conductivity in the PVDF casting solution were also evaluated.