Waste PET derived Janus fibrous membrane for efficient oil/water emulsions separation

Effective treatment of diversified and complicated oily wastewater is of great significance but remains challenging, Janus membrane with asymmetric wettabilities is an urgent need in the field of ideal oil-water separation. Herein, this work presents a facile and versatile method to fabricate polydopamine/polyethylene terephthalate/polyvinylidene fluoride (PDA/PET/PVDF) Janus membrane via sequential electrospinning technique and surface chemical modification. Specifically, the PDA/PET side of the resultant Janus membrane possesses superhydrophilic/underwater superoleophobic properties and the PVDF side of Janus membrane exhibited hydrophobic/superoleophilic surface. It is indicated that the resulting asymmetric wettability of Janus membrane is controlled only by reversal, and the membrane can work as water/oil-removing material for on-demand emulsion separation. In addition, the as-obtained Janus membrane preserved asymmetric wettability for highly efficient separation of various oil-in-water emulsions (separation efficiency of 99.7 % and separation flux of 1,770 L·m-2·h-1) and water-in-oil emulsions (separation efficiency of 99.5 % and separation flux of 19,200 L·m-2·h-1bar-1). Furthermore, the Janus PET membrane also showed excellent mechanical property and good antifouling activity against contaminants due to the hierarchical porous structure. The waste-derived PET Janus fibrous membranes with mild fabrication processes show prominent separation efficiency, excellent mechanical property and good antifouling activity, which is of great importance for providing a flexible strategy to fabricate Janus membranes by using waste plastic as raw materials, as well as demonstrating a solution for multifunctional oil/water separation and purification.