Embedding FeOOH/g-C3N4 Heterojunctions Into Polyamide Layers for Photocatalytic Self-Cleaning Nanofiltration Membranes

Membrane fouling critically hinders nanofiltration (NF) for dye wastewater treatment. In this work, FeOOH was in situ loaded onto g-C 3 N 4 nanosheets, and the resulting FeOOH/g-C 3 N 4 composites were embedded into polyamide (PA) layers via interfacial polymerization to fabricate a self-cleaning NF membrane. The heterojunction configuration of the FeOOH/g-C 3 N 4 composites was confirmed by SEM, TEM, and FTIR, and was observed to promote their photocatalytic oxidation under visible light. The incorporation of FeOOH/g-C 3 N 4 enhanced the surface hydrophilicity and electronegativity of the membranes. Moreover, the intercalation of FeOOH on g-C 3 N 4 endowed the PA layer with additional water channels or interfacial voids, enhancing membrane permeability while ensuring retention performance, achieving a pure water permeance of 18 L·m −2 ·h −1 ·bar −1 and rejections of > 95% for dye molecules and > 90% for divalent salts. Benefiting from the photocatalytic capability of the FeOOH/g-C 3 N 4 heterojunction, the FeOOH/g-C 3 N 4 @PA membrane exhibited improved fouling resistance and high self-cleaning properties after three reuse cycles, maintaining a flux recovery ratio of over 97%, utilizing only a simple photocatalytic degradation operation. This work may provide a new strategy for fabricating antifouling and self-cleaning nanofiltration membranes for water treatment applications.