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°. 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·m· −2 ·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°). Graphical