Underwater superoleophobic polyvinylidene fluoride membranes using sulfonated dopamine and polyethyleneimine as additives for the separation of oily water

Oil-fouling of the membranes limits further application in the separation and purification of oil-in-water emulsions. Here, anti-oil fouling membranes are engineered by the method of non-solvent induced phase separation (NIPS) which enriches the polysulfonated dopamine (PSDA) and polyethyleneimine (PEI) (PSDA-PEI) to the top surface from mixed casting solution. The obtained membrane achieves excellent anti-oil fouling property as high as 98.2% oil rejection, yet it still possesses good flux of 2362.5 ± 110.9 and 1252.3 ± 71.8 L m −2 h −1 for the separation of 1,2-dichloroethane-in-water and toluene-in-water emulsions. This can be attributed to outstanding hydrophilicity and super underwater superoleophobicity for mussel-inspired PSDA-PEI layer. In addition, the membrane also has excellent stability in acid (pH 1, 3, and 5) or alkali (pH 10 and 12) solutions. This work provides a facile method to engineer underwater superoleophobic membranes with excellent anti-oil fouling by mussel-inspired chemistry for oily water treatment. Graphical