Fabrication of a\nZIF-8/PVA Membrane on PVDF Fiber\nby Spray for the Highly Efficient Separation of Oil-in-Water Emulsions

In human life and production, excessive oily wastewaters\ncontaining\ndetergents are produced and discharged, causing severe environmental\npollution and water resource problems. A metal–organic framework\n(MOF)-based membrane is an economical and environmentally friendly\ntool for emulsion separation but is limited by a complex preparation\nprocess and poor flexibility. Herein, we developed a simple method\nto synthesize a MOF-based mixed-matrix membrane (MMM) by spray and\nfabricated the membrane on poly(vinylidene fluoride) (PVDF) fibers\nvia postdeposition and in situ growth manners. The prepared ZIF-8/PVA\nMMMs have uniform distribution of ZIF-8 particles and poly(vinyl alcohol)\n(PVA) on the PVDF fibers. PVA improved the adhesion between the ZIF-8\nparticles and between the MOF layer and PVDF fiber, endowing the separation\nmembrane with high flexibility and bendability. The prepared ZIF-8/PVA\nmembrane exhibited hydrophilicity and underwater superoleophobicity,\nwhich showed high separation efficiency and considerable water flux\nfor emulsions, emulsion containing dye, and surfactant-stabilized\nemulsion. In addition, the fabricated ZIF-8/PVA/PVDF fibers exhibited\ngood antifouling property and flexibility and can maintain stable\nseparation efficiency after working several times and even under bending,\ndemonstrating the stability and potentiality of the ZIF-8/PVA/PVDF\nfibers in practical applications. This work paves a new avenue for\nthe synthesis and application of MOF-based MMMs.