Evaluation of self-cleaning performance of the modified g-C3N4 and GO based PVDF membrane toward oil-in-water separation under visible-light

Photocatalytic membranes (PMs), coupling of membrane filtration and photocatalysis, have exhibited the potential for application in the wastewater treatment. In this study, we firstly adopted the supramolecular aggregates of melamine (M), cyanuric acid (C), and urea (U) in specific dimethyl sulfoxide (DMSO) as precursors to prepare carbon nitride MCU-C3N4 with high photocatalytic performance, and a kind of novel-designed photocatalytic membrane was prepared via filtrating the mixture of graphene oxide (GO) nanosheets and MCU-C3N4 on PVDF membrane supports, and then crosslinked using glutaraldehyde (GA) to construct a steady coating on the GO/MCU-C3N4/PVDF membrane. GO/MCU-C3N4/PVDF composite membrane exhibited higher permeation flux than that of GO/PVDF membrane and exhibited excellent separation performance for oil-in-water emulsion. A visible light-driven self-cleaning four-stage filtration by a self-built dead-end filtration system was carried out to evaluate membrane antifouling property, and GO/MCU-C3N4/PVDF membrane (M2) possessed higher flux recovery ratio (FRR) (∼92.36%) and lower irreversible fouling resistance (Rir) ratio (∼8%) under 30min visible-light irradiation, maintaining relatively higher FRR (>72%) during 4 cycling of four-stage filtrating experiments. GO/MCU-C3N4/PVDF PMs are equipped with high permeation flux, separation performance, anti-fouling property and stability, indicating potential application in water treatment.