CQDs/ZIF-L Derivatives Modified PES Ultrafiltration Membranes: Achieving Excellent Self-Cleaning and Antibacterial Properties

Membrane fouling remains a critical obstacle for the application of polyethersulfone (PES) ultrafiltration in industrial wastewater treatment. In this work, a novel multifunctional composite membrane was developed by co-embedding carbon quantum dots (CQDs) and ZIF-L-derived carbon-doped ZnO (C-ZnO) nanoparticles into a PES matrix via the reverse thermally induced phase separation (RTIPS) method. The optimized membrane M3 contains 0.05 wt% CQDs and 0.02 wt% C-ZnO. It exhibited a remarkably hydrophilic surface with a water contact angle of 51.8°. Compared to membranes fabricated by conventional non-solvent induced phase separation (NIPS), the RTIPS method produced a structure with a highly porous surface and an interconnected sponge-like support, effectively breaking the permeability-selectivity trade-off. The optimized composite membrane exhibited a superior pure water permeability of 1555 L m −2 h −1 while maintaining a high humic acid rejection of 91.9%. This membrane also demonstrated robust long-term antifouling stability and a photocatalytic flux recovery rate of 65.8% under visible light. Furthermore, it achieved nearly 100% antibacterial activity against E. coli and S. aureus , attributed to a dual-defense mechanism combining a physical hydration layer with the chemical action of photocatalysis and Zn 2+ release. These findings highlight the significant potential of this RTIPS-fabricated CQDs/C-ZnO/PES membrane as a robust solution for high-performance wastewater treatment.