Facile fabrication of underwater superoleophobic membrane based on polyacrylamide/chitosan hydrogel modified metal mesh for oil-water separation

Using chemically etched stainless steel mesh (SSM) as matrix, chitosan (CS) as the hydrophilic component and acrylamide as (AAm) monomer, the underwater superoleophobic membrane (PAAm/CS@SSM) for oil-water separation was prepared by free radical polymerization initiated by ultraviolet light. The composition, morphology, underwater oil contact angle, and structure of PAAm/CS@SSM were characterized by Fourier-transform infrared spectroscopy, x-ray powder diffraction, scanning electron microscopy, and confocal laser scanning microscopy. The underwater oil contact angles of PAAm/CS@SSM could reach 154.5 degrees. When the number of oil-water cycles reached 20 times, the oil-water separation efficiency of PAAm/CS@SSM was larger than 99%. When the oil-water ratio is 1:3, 1:2, 1:1, 2:1, 3:1, the oil-water separation flux of PAAm/CS@SSM was 2096.8, 4457.9, 4735.7, 5395.7, and 3606.9 L center dot m center dot(-2)center dot h(-1), respectively. When oils are n-hexane, petroleum ether, vegetable oil, and liquid paraffin, the oil-water separation efficiency of PAAm/CS@SSM was 99.0%, 97.7%, 97.2%, and 99.3%, respectively. After the wear resistance test, the PAAm/CS@SSM membrane still exhibited underwater super-oleophobicity (>150 degrees).