Embedding FeOOH /g‐C ₃ N ₄ Heterojunctions Into Polyamide Layers for Photocatalytic Self‐Cleaning

ABSTRACT

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.