Amphibious Superamphiphilic Nanofibrous Membrane with Oil Coalesced Porous Structure for Highly Efficient Emulsion Separation

Conventional membranes for oily wastewater treatment mainly relying on the size-sieving effect typically suffer from low permeation flux and short service life due to poor coalescence capability and susceptibility to oil fouling under practical conditions. Herein, we fabricated an amphibious superamphiphilic porous nanofibrous membrane doped with g-C₃N₄@TiO₂ through water vapor-induced electrospinning to achieve superhydrophilicity in air and superoleophilicity underwater. Leveraging amphibious superamphiphilicity enabled by surface energy reconfiguration coupled with an internally interconnected porous structure, the membrane can adsorb tiny oil droplets underwater. These adsorbed droplets rapidly coalesce into a continuous macroscopic oil phase that can be discharged together with water through the membrane, giving rise to two distinct well-defined phases. This unique demulsification pathway transcends the traditional constraints of micron-sized porous membranes in handling submicron/nanosized oil-in-water emulsions, while affording a high permeance and efficiency of 2785 L m^-2 h^-1 and 99.78%, respectively. Moreover, the addition of g-C₃N₄@TiO₂ significantly enhances the membrane's ability to self-clean under visible light. Under visible-light irradiation, the membrane can efficiently degrade oil foulants within 4 h, achieving a water flux recovery rate of 98.08%. This work offers a new strategy for designing advanced membranes with efficient oil coalescence and a sustainable emulsion separation performance.