Vein-supported porous membranes with enhanced superhydrophilicity and mechanical strength for oil-water separation

Abstract

Oil fouling is a major obstacle for the efficient and reliable oil-water separation of mesh-based membrane processes. Innovations in membrane materials and preparation processes are therefore needed to develop anti-oil-adhesion strategies. This study reports a series of vein-supported porous membranes (VPMs) fabricated by casting polyacrylonitrile (PAN) on veins through non-solvent induced phase separation, confirmed by FTIR, SEM and XRD characterizations, and applied as an effective oil-water separation membrane. Benefiting from the combination of tubular-like vein and hydrophilic PAN, the resultant VPM demonstrates a fine-tunable morphology and superhydrophilicity, extremely boosting underwater superoleophobicty, mechanical strength and superior performance for oil/water separation to various oily mixtures/emulsions, showing underwater oil contact angles over 157° and nearly zero underwater oil adhesion. In oil-water mixture separation process, a separation efficiency of > 99% and ultrahigh permeation flux of 9592 LMH can be achieved under gravity conditions using VPM-2 (casting with 2 wt% PAN). For oil-water emulsion separation, a highest flux of 3011 LMH and trace oil concentration <10 ppm in the filtrate was generated using VPM-9 (casting with 9 wt% PAN) under a low external pressure of 3 kPa. The VPM-2 membrane is further carried out a 40-h cycling separation, showing a constantly stable water flux of ~6000 LMH. The developed VPMs open a bright path to use biomaterials for design and fabrication of novel oil-water separation membrane.