Ethanol-induced one-step fabrication of superhydrophobic-superoleophilic poly(vinylidene fluoride) membrane for efficient oil/water emulsions separation

Surfactant-stabilized emulsions, a main type of hazardous oil/water mixtures have been afflicting human beings for decades. In this work, a highly porous PVDF/PDMS blend membranes with superhydrophobic-superoleophilic property was successfully prepared through ethanol-induced phase inversion. This facile, low cost and effective one-step membrane-forming method endowed the membrane with a superwetting micro-nano hierarchical surface and an interconnected porous internal structure. The optimal membrane exhibited a water contact angle of 164 +/- 1.9 degrees and an oil contact angle of 0 degrees. With high porosity and superior selective wettability, the PVDF/PDMS blend membranes can separate multifarious surfactant-stabilized nanoscale emulsions quickly. The optimal membrane shows a filtration flux of 855 +/- 45 L m(-2) h(-1) (the separation efficiency exceeds 99.81 %) when driven by gravity merely. In addition, PVDF/PDMS blend membranes have an excellent reusability in separating the surfactant-stabilized water-in-oil emulsions. These results clearly demonstrate that this membrane-forming method may provide a new reliable pathway for membrane fabrication for oil/water emulsion separation.