One-step facile fabrication of PVDF/graphene composite nanofibrous membrane with enhanced oil affinity for highly efficient gravity-driven emulsified oil/water separation and selective oil absorption

Highly efficient separation of emulsified oily wastewater, especially for surfactant-stabilized water-in-oil emulsions is urgently demanded and still worldwide challenge. Herein, a superoleophilic and under oil superhydrophobic Poly (vinylidene fluoride) (PVDF)/graphene (GE) composite nanofibrous membrane (GPNM) was fabricated through a simple one-step electrospinning strategy for highly efficient gravity-driven surfactant-stabilized water-in-oil emulsions separation. The resultant membrane possessed water contact angel of 140.1°±1.1°, oil contact angel of nearly 0°, as well as under oil ultralow water adhesion ability. Furthermore, the morphology, pore size and surface wettability of as-prepared nanofibrous membranes were simply tuned by adjusting the concentration of GE in electrospinning solution. Thanks to the narrow pore size distribution, high porosity (＞92.8%), and the intrinsic strong oil affinity of GE nanosheet, the composite membrane showed outstanding Span 80 surfactant-stabilized water-in-oil emulsions separation efficiency as high as 99.8% with corresponding permeation flux up to 23794 ± 928 L m−2 h−1 bar−1 during gravity-driven separation process. The exceptional oil absorption performance was also displayed by collecting floated oils on water surface. The results would make our composite nanofibrous membranes a great promise of dealing with practical oily wastewater remediation.