Sacrifice\nTemplate Strategy to the Fabrication of\na Self-Cleaning Nanofibrous Membrane for Efficient Crude Oil-in-Water\nEmulsion Separation with High Flux

Abstract

The superhydrophilic/underwater superoleophobic\nmembrane materials\nhave attracted considerable attention in oil/water separation. However,\nmost materials are extremely susceptible to pollution during oil–water\nseparation, which drastically restricts their widespread applications.\nHerein, a momordica-charantia-like nanofibrous membrane (MCNM) with\nunderwater superoleophobic performance was fabricated through a sacrifice\ntemplate strategy by the electrospinning solution of zeolitic imidazolate\nframework-8 (ZIF-8) and polyacrylonitrile particles. The opened voids\nand wrinkles left after removing the template of nanocrystals ZIF-8\nnot only increased the porosity and roughness of the as-prepared fibrous\nmembrane but also tremendously improved the underwater superoleophobicity.\nTherefore, the as-prepared MCNM showed excellent self-cleaning performance\ntoward crude oil under water, avoiding the decrease of the separation\nefficiency and flux caused by membrane fouling during oil–water\nseparation. Meanwhile, the separation efficiency of various surfactant-stabilized\noil-in-water emulsions was higher than 99.6% with a flux up to 1580\n± 30 L m^–2 h^–1 solely driven\nby gravity. Moreover, no obvious wrinkles and cracks were observed\non the resulted nanofibrous membrane after the sand impact and bent\ntesting. More importantly, the as-prepared MCNM still maintained exceptional\nunderwater superoleophobicity in harsh environment (3.5 wt % NaCl,\n4 M HCl, 50 °C hot water) even after ultrasound for 1 h. The\nrobust mechanical and chemical stability makes the antifouling MCNM\nexhibit tremendous potential for practical applications in dealing\nwith oily wastewater in the future.