Nucleation-Directed Mineralized Electrospun Nanofiber Membrane for Ultra-Low-Pressure Oil-in-Water Emulsion...

The inevitable adhesion and accumulation of oily pollutants on membrane interfaces throughout the oil-water separation processes lead to severe performance degradation, underscoring the urgent need for effective and energy-saving antifouling strategies. Herein, a nucleation-directed mineralization strategy is developed to prepare a Cu₃(PO₄)₂ mineralized nanofiber membrane (PAN/CuP) with a micro/nanoparticulate architecture. By preanchoring copper ions onto carboxyl-functionalized electrospun polyacrylonitrile nanofibers as nucleation sites, a uniform and robust mineralized layer is controllably grown, imparting exceptional surface hydrophilicity and underwater superoleophobicity. The phosphate-rich mineral coating endows the PAN/CuP membrane with strong hydration capability, enabling complete oil detachment without prewetting treatment. Under gravity-driven or ultralow-pressure conditions (∼0.01 MPa), the membrane achieves efficient separation of both immiscible oil-water mixtures and surfactant-stabilized emulsions, with separation efficiencies exceeding 99.4%. Benefiting from its robust antifouling capability, the PAN/CuP membrane stably sustains a high flux of 447.3-763 L m^-2 h^-1 throughout 300 min of continuous cross-flow filtration of oil-in-water emulsions. The fouled membrane can be readily restored by simple water rinsing, attaining a flux recovery ratio (FRR) > 99.2% and an irreversible fouling ratio below 1%, demonstrating nearly complete fouling reversibility. This work provides a robust and energy-efficient strategy for constructing high-performance mineralized nanofiber membranes, offering new insights into the design of advanced antifouling membranes for practical oily wastewater treatment.