A TA-PEI “molecular bridge” enabled ZIF-8/PES membrane with enhanced alkali resistance for oily electroplating pretreatment wastewater

A TA-PEI “molecular bridge” strategy was devised for robust in-situ growth of ZIF-8 on PES membranes. • The composite membrane exhibited 175.48 L·m −2 ·h −1 flux and 98.29% oil rejection. • The membrane exhibited outstanding stability in highly alkaline (pH 12) environments. • Mechanical strength was significantly improved due to ZIF-8 reinforcement and crosslinking synergy. The treatment of highly alkaline, surfactant-stabilized oily wastewater from electroplating pretreatment poses a significant challenge for membrane technology. Conventional polyethersulfone (PES) ultrafiltration membranes suffer from severe fouling and chemical degradation under such harsh conditions. To address these dual limitations of performance and stability, this study developed a “blending-in-situ growth” strategy to fabricate a ZIF-8/TA-PEI/PES composite membranes. The TA-PEI interlayer acts as a molecular bridge, enabling uniform and robust anchoring of the ZIF-8 coating. The optimized membrane exhibited a pure water flux of 175.48 L·m −2 ·h −1 (≈4.5× that of pristine PES) and a high flux recovery rate of 75.86%. For surfactant-stabilized oil-in-water emulsions, it achieved 98.29% rejection, maintaining 96.54% efficiency over 10 cycles. Crucially, it demonstrated exceptional alkali resistance, retaining 92.17% rejection after 72 h at pH 12, alongside a tripled tensile strength (3.01 MPa). This work provides a durable and high-performance membrane solution engineered specifically for the demanding separation of complex industrial wastewater. Download: Download high-res image (249KB) Download: Download full-size image