Superwetting Polyvinlydene Fluoride Membranes with Micro‐Nano Structure for Oil‐in‐Water Emulsion Separation

Membrane technology is seen as one of the useful strategies for the treatment of oily wastewater, but the membrane fouling in the process of membrane filtration seriously may affect some properties and time-consuming. Hydrophilic membrane surface can reduce membrane fouling. The appropriate design for membrane composition and surface structure can transform membrane surface with expected performance. In this work, hydrophilic polyvinylidene fluoride (PVDF) membranes with micro-nanostructure are fabricated by in situ synthesis and layer-by-layer assembly strategies. A zeolitic imidazolate framework-8 (ZIF-8) and tannic acid are used to construct microstructure and support hydrophilic groups. The water contact angle and water flux of initial PVDF membrane are 110.67° and 6585.7 L m−2 h−1, respectively, while the optimally modified membrane possesses water contact of 14.5° and water flux of 13641.8 L m−2 h−1. The modified membrane not only owns good underwater oil repellency and oil adhesion resistance but also processes good separation performance for surfactant stable oil-in-water emulsion. Furthermore, the modified membranes exhibit constant permeability and underwater oleophobicity in cycling experiments and harsh environments, indicating that the modified coating has stability against shedding of the modified materials. This method supports valuable references for MOF application in the field of oil–water separation.