Construction of a multilayer structured separation membrane based on TiO₂/ZIF-8 and CS-SDAEM polymer brush with enhanced self-cleaning and antifouling performance

Multilayer PVDF membrane with TiO₂/ZIF-8 and CS-SDAEM brush. • Superhydrophilic: water contact angle drops to 0° within 1.3 s. • Pure water flux 1440 L·m⁻²·h⁻¹ and dye rejection over 93%. • Synergy enables > 93% flux recovery after 10 cycles without cleaning. • Excellent stability against ultrasonication, abrasion, and harsh chemicals. Conventional polymer separation membranes suffer from severe fouling, limiting their efficiency in wastewater treatment. To address this issue, we develop a multilayer-modified PVDF membrane by integrating a TiO₂/ZIF-8 photocatalytic layer and a CS-SDAEM zwitterionic polymer brush. The TiO₂/ZIF-8 nanoparticles are deposited on the membrane surface, followed by crosslinking and grafting of CS-SDAEM, which forms a robust hydration layer and physically encapsulates the nanoparticles. The resulting membrane exhibits superhydrophilicity (water contact angle drops to 0° within 1.3 s) and achieves a pure water flux of 1440 L·m⁻²·h⁻¹ with over 93% dye rejection for various dyes. Owing to the synergistic adsorption, photocatalysis, and antifouling effects, the membrane shows excellent self-cleaning ability, maintaining a flux recovery rate > 93% after 10 photocatalytic cycles without chemical cleaning. In addition, it exhibits excellent mechanical and chemical stability when subjected to ultrasonication, abrasion, and exposure to aggressive chemicals. This multilayer strategy offers a promising route to construct high-performance, long-lasting separation membranes for advanced water treatment. Download: Download high-res image (349KB) Download: Download full-size image