Smart Thermoresponsive CoZn-ZIF Decorated PVDF/PNIPAM Nanofiber Membrane for Switchable Emulsion Separation and Catalytic Dye Degradation

The development of intelligent, environmentally responsive oil-water separation membranes with reversible wettability presents a promising strategy for controllable emulsion separation and the advanced treatment of complex oily wastewater. Wastewater. In this study, a novel thermally responsive membrane with switchable wettability between superhydrophilic and superhydrophobic states was fabricated via in situ growth of bimetallic metal-organic frameworks (CoZn-ZIF) on electrospun poly(vinylidene fluoride)/poly(<i>N</i>-isopropylacrylamide) (PVDF/PNIPAM) nanofiber membranes. The resulting PVDF/PNIPAM@CoZn-ZIF membrane leverages the thermally induced reversible conformational transition of PNIPAM to exhibit underwater superoleophobicity below its lower critical solution temperature (LCST) and under-oil superhydrophobicity above LCST. This switchable wettability enabled efficient on-demand separation of both oil-in-water (O/W) and water-in-oil (W/O) emulsions, achieving water permeation fluxes exceeding 1900 L·m^-2·h^-1 and oil permeation fluxes over 1150 L·m^-2·h^-1, with separation efficiencies above 99.00% and 99.60%, respectively. Moreover, the embedded Co₁Zn₃-ZIF served as a catalyst to activate peroxymonosulfate (PMS), generating reactive oxygen species (^·OH and^·SO₄^-) and enabling rapid degradation of methylene blue, with a removal efficiency of 99.92% within 15 min. This study presents a multifunctional composite membrane as an intelligent, efficient platform for integrated oil-water emulsion separation and organic pollutant remediation.