Electro-Induced Coordination Reconfiguration Strategy Guiding Water State Evolution against Gel-like Fouling in Ultrafiltration

Ultrafiltration (UF) is a prominent technology for efficiently treating surface water, but the conventional UF process suffers from severe gel-like membrane fouling induced by natural organic matter (NOM) and coexisting multivalent cations. Here, we propose an electro-induced coordination reconfiguration (EICR) guiding water state evolution strategy for mitigating gel-like membrane fouling by applying potential to the prepared electrically conductive carbon nanotube polyvinylidene fluoride hollow fiber membrane (CNT-PVDF HFM). Comprehensive in situ electrochemical experiments and theoretical simulations reveal that the EICR strategy disrupted the coordination between NOM and multivalent cations, preventing the formation of a cross-linking porous network hydrogel structure and thereby releasing water molecules from steric constraints. The interfacial water state undergoes a transition from interstitial water to free water, facilitating the permeation of water molecules across the foulant layer. The decrease in filtration resistance of water state evolution was estimated at 81.4% of the total reduced fouling resistance through Flory-Huggins lattice theory, suggesting its dominant role in fouling mitigation rather than conventional electrostatic repulsion. We demonstrate excellent antifouling performance in surface water treatment, with the backwashing interval of CNT-PVDF HFM membrane at -1.5 V vs Ag/AgCl being extended by 12-fold compared to the conventional commercial PVDF membrane. This study highlights the importance of guiding water state evolution in mitigating complex gel-like membrane fouling and opens a promising gateway for future development of proactive antifouling strategies.