Piezoelectric Hydrogel Membranes Enabling Hydraulically Self‐Regulated Active‐Passive Antifouling for Oil‐Water Separation

Membrane fouling caused by the diffusion and adsorption of oil droplets during oil‐water separation severely hinders the long‐term operation of membrane modules, highlighting the imperative for innovative membrane fouling mitigation strategies. Herein, a molybdenum disulfide/polyvinyl alcohol/barium titanate/microfibrillated cellulose (MoS 2 /PVA/BaTiO 3 /MFC, MPBM) membrane was engineered for active‐passive synergistic antifouling during emulsion separation. As a passive antifouling strategy, membrane surface functionalization with a MoS 2 /PVA hydrogel constructs a dense hydration barrier, which reduces underwater crude oil adhesion to 0.73 µN and enables a separation efficiency exceeding 99.28% for different emulsions. The incorporation of piezoelectric components (BaTiO 3 and MoS 2 ) endows the MPBM membrane with great electromechanical conversion capability and active antifouling performance. Notably, during emulsion separation, the intrinsic pulsed hydraulic pressure (0.1 bar) triggers a piezopotential of −130 to −160 mV across the membrane. Based on the piezoelectric effect, a dynamically coupled force field combining electrostatic and dielectrophoretic forces is constructed, enabling the simultaneous active detachment of anionic surfactants and oil droplets from membrane pores. This work provides an energy‐saving and effective solution for the sustainable separation of oil‐in‐water (O/W) emulsions, offering valuable insights for advancing active‐passive synergistic antifouling technologies in membrane‐based wastewater remediation.