Cellulose Sponge with Superhydrophilicity and High Oleophobicity Both in Air and under Water for Efficient Oil-Water Emulsion Separation

Oil-water emulsions stabilized by surfactants are fine dispersions of oil in water or of water in oil and difficult to separate which will lead to serious water pollution. A more recent development is the ability to fabricate oleophobic-hydrophilic surfaces in air, which are not easy to construct due to the difference surface tension between water and oil. Herein, a cellulose sponge with multipore structure is fabricated to increase the removal efficiency. Amphiphilic molecular brushes of polyethylene glycol with short perfluorinated end caps (F-PEG) are grafted on cellulose sponges to solve the contradictory relation of hydrophilicity and oleophobicity and improve oil/ water selective wettability and fouling resistance. Besides, stable superhydro-philicity and superoleophobicity under water, corrosive liquids, and high oleophobicity in air conditions are exhibited in the F-PEG grafted porous cellulose sponges with textured surfaces (F-g-CS). And the separation efficiency and rate of F-g-CS with surface of nanopores are 99.92% and 180 L m(-2) h(-1), while that of micropores are 99.83% and 297 L m(-2) h(-1) only under gravity. It is demonstrated that the grafting F-PEG molecules imparted F-g-CS of micropores surface with high flux and separation efficiency simultaneously. Furthermore, antifouling property and collection of water in oil-water mixture without fouling are possessed in F-g-CS.