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

For high-viscosity wastewater containing crude oil, the membrane material is easily clogged with contamina-tions, resulting in decreased flux and potentially loss of separation ability. In this study, a superhydrophilic/ underwater superoleophobic PVDF membrane (PVDF-PC-ePL) was designed by the self-polymerization of proanthocyanidins (PC) and the grafting reaction of e-polylysine (ePL), which showed a rough micro-nano structure without adding the inorganic particles. The PVDF-PC-ePL 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-ePL membrane was 165 degrees, after the PVDF-PC-ePL 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 degrees and the water contact angle was always 0 degrees. The modification method on the PVDF membrane proposed in this study offers a fresh perspective and choice for preparing the oil-water separation materials.