Anchoring metal organic frameworks on nanofibers via etching-assisted strategy: Toward water-in-oil emulsion separation membranes

Abstract

The zeolitic imidazolate framework-71/poly(vinylidene fluoride-hexafluoropropylene) (ZIF-71/PVDF-HFP) nanofibrous membrane was fabricated via anchoring ZIF-71 on PVDF-HFP nanofibrous membrane with targeted sites assisting. The ZIF-71 facilitated demulsification with increasing hydrophobicity. Eventually, the ZIF-71/PVDF-HFP nanofibrous membrane exhibited excellent separation performance for water-in-oil emulsions. • Etching-assisted strategy is used to anchor ZIF-71 nanoparticles on nanofibers. • The ZIF-71 increased roughness and hydrophobicity (162.1°). • Ultrahigh flux (4827.97 L m -2 h −1 ) and high efficiency (>99%). • The membranes exhibited excellent antifouling and cyclic stability. Efficiently separating water-in-oil emulsions is urgent demand and still worldwide challenge. Nanofibrous membranes with super-wetting surface have drawn wide concern to solve it. Herein, under-oil superhydrophobic zeolitic imidazolate framework-71/poly(vinylidene fluoride-hexafluoropropylene) (ZIF-71/PVDF-HFP) nanofibrous membranes were prepared via electrospinning and etching-assisted in-situ growth strategy for water-in-oil emulsions separation. ZnO was etched to create adsorption sites, ensuring the dispersed ZIF-71 nanoparticles firmly anchoring on nanofibers. The membranes showed under-oil superhydrophobicity with under-oil water contact angle 162.1°. The membranes could effectively separate a variety of water-in-oil emulsions (such as dichloromethane, chloroform, and toluene) by gravity. The separation efficiency of all emulsions was higher than 99% and the flux of water-in-chloroform without surfactant reached up to 6577.68 L m -2 h −1 . Moreover, the membranes exhibited excellent cyclic stability and anti-fouling. Therefore, the MOF/nanofibrous membranes fabricated by etching-assisted strategy are promised candidates for efficient oil/water separation.