A tannic acid-iron co-modified polyphenylene sulfone ultrafiltration membrane with improved surface hydrophilicity...

This study presents the fabrication and evaluation of novel ultrafiltration (UF) membranes based on a polyethersulfone (PES) matrix incorporating tannic acid (TA) and TA-Fe³⁺ coordination complexes (ITF) via a dip-coating approach, with the aim of enhancing surface hydrophilicity and antifouling properties. The successful integration of TA and ITF within the PES structure were verified using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). As a result of this successful integration, membranes modified with ITF for the optimal membrane composition (TA: Fe³⁺ molar ratio of 10:1) demonstrated a marked increase in surface hydrophilicity, as evidenced by a reduction in the water contact angle from 70.92° to 52.14° and a corresponding rise in surface free energy. Evaluation of separation performance showed significant enhancements in both pure water flux and bovine serum albumin (BSA) rejection, achieving values of 139.29 L m^-2·h^-1 and 99.15%, respectively. Additionally, the modified membranes displayed remarkable resistance to fouling, demonstrating a stable flux recovery ratio (FRR) of 90.45% across four filtration cycles with an irreversible fouling ratio (Rir) of 9.57% and a reversible fouling ratio (Rr) of 80.88% for the optimal composition. The superior antifouling properties can be primarily ascribed to the establishment of a stable hydration layer and pronounced electrostatic repulsion effects. The ITF coatings were stably anchored onto the PES membrane surface via hydrogen bonding and π-π stacking, ensuring long-term operational stability. Therefore, modifying the PES matrix with ITF complexes represents a promising strategy for fabricating high-performance UF membranes, with enhanced filtration efficiency, hydrophilicity, and fouling resistance, positioning them as sustainable options for complex water treatment applications.