Polyphenol-engineered superwetting membranes with wrinkled microspherical organizations for high-efficient oil/water separation

Abstract

Superwetting membranes, especially superhydrophilic and underwater superoleophobic membranes, are promising functional materials for oily wastewater treatment. Most superwetting membranes are charactered by micro-porous membranes with hierarchical morphology and hydrophilic composition. However, challenges still remain to synthesize superwetting membranes directly via phase separation that can overcome the limitations of the inherent features of the substrate and the need of multistep post-processing procedures. In this study, a facile strategy is reported to fabricate superwetting membranes via combining multiple polyphenol-mediated complexation with nonsolvent-induced phase separation (MPMC-NIPS). The metal-phenolic gelation networks (MPgNs) are formed within membrane matrix by in situ complexation in the casting solution, and followed by the interfacial complexation of F127-phenolic hydrogen-bonding networks (FPhNs) during the coagulation process. The MPgNs create surface structures with wrinkled microspherical organizations, and the FPhNs facilitate surface hydrophilicity. The resulting specific hierarchical wrinkled and hydrophilic surface architectures endow the membranes with superhydrophilicity and underwater superoleophobicity. The as-prepared PVDF/TA-Ti-SF127 membrane exhibits excellent emulsion permeation flux up to 6265 L m-2 h-1 bar-1 with high separation efficiency of over 99.6% and superior antifouling performance. This study highlights a promising and facile route to design superwetting membranes with tailored hierarchical wrinkled surface morphology for high-efficient oil-in-water emulsion separation, which contributes to the on-demand design and construction of micro-porous superwetting membranes.