Rational designed of PVDF membrane based on surface modification of εPL anchored by PC for crude oil emulsion separation

Abstract

For high-viscosity wastewater containing crude oil, the membrane material is easily clogged with contaminations, resulting in decreased flux and potentially loss of separation ability. In this study, a superhydrophilic/underwater superoleophobic PVDF membrane (PVDF-PC-εPL) was designed by the self-polymerization of proanthocyanidins (PC) and the grafting reaction of ε-polylysine (εPL), which showed a rough micro-nano structure without adding the inorganic particles. The PVDF-PC-εPL membrane displayed outstanding self-cleaning ability for high-viscosity crude oil, and the separation efficiency of the crude oil-in-water emulsion could be greater than 99.4%. The underwater oil contact angle (UWOCA) of the PVDF-PC-εPL membrane was 165°, after the PVDF-PC-εPL membrane had been exposed to air or water for 6 weeks, or soaked in different pH or seawater for 24 h, the UWOCA remained above 154° and the water contact angle was always 0°. The modification method on the PVDF membrane proposed in this study offers a fresh perspective and choice for preparing the oil-water separation materials.