Controllable Preparation of Novel UiO-66-NH2/g-C3N5 Thin-Film Nanocomposite Nanofiltration Membranes with Efficient Photocatalytic Pollutant Removal and Anti-Fouling Ability

To overcome membrane permeation selectivity defects and mitigate membrane fouling, a novel nanocomposite, UiO-66-NH 2 /g-C 3 N 5 (UNCN), was designed and synthesized. Notably, this composite overcomes the inherent limitations of UiO-66-NH 2 (limited visible light absorption) and g-C 3 N 5 (low specific surface area). The optimal composite ratio was determined to be 3:7 through systematic optimization. The UNCN-3:7 nanocomposite was then embedded into the polyamide selective layer on polysulfone via in situ interfacial polymerization under optimal conditions, resulting in a thin film nanocomposite (TFN) Nanofiltration membrane. Characterization revealed that the UNCN-3:7 Nanocomposites were uniformly distributed within the polyamide (PA) matrix. The resulting TFN Nanofiltration membrane possessed an ultrathin, positively charged selective layer with enhanced hydrophilicity, evidenced by a reduction in water contact angle from 60.3° to 47.3°. It exhibited a 43% increase in pure water permeability compared to the unmodified thin film composite (TFC) membrane (52.7 vs. 36.9 L·m −2 ·h −1 ·bar −1 ), while maintaining an excellent Na 2 SO 4 retention rate (> 96%). Furthermore, the membrane demonstrated excellent photocatalytic degradation performance, superior anti-fouling properties (flux recovery rate > 92%), and stable long-term operation. These results indicate that the construction of the novel UNCN nanocomposite Nanofiltration membrane presents an effective strategy to address membrane fouling issues.