A stable underwater superoleophobic membrane constructed by CuO oriented rods and PAA water-adsorbent resin for fast and high efficient oil-water separation

The practical application of filter membranes for oil-water separation requires high efficient, large flux and excellent stability. Hydrogel membrane with superhydrophilicity and underwater superoleophobicity has been considered as an ideal material for efficient separation of oil-water mixture. However, hydrogel materials are generally fragile and easy to dehydrate. In this work, inorganic CuO oriented-rods framework was used to support water-adsorbent polyacrylic acid (PAA) resin for constructing superhydrophilic-superoleophobic composite hydrogel membrane. The as-prepared composite membrane displayed stable underwater superoleophobicity during swelling-drying cycles and abrasion test. In "bottom-injection" filter apparatus, the CuO@PAA membrane exhibited high separation efficiencies, above 99.90%, for kerosene-water, hexadecane-water, soybean oil-water and rapeseed oil-water mixtures with water penetration fluxes larger than 5700 L.m(-2).h(-1). The excellent separation efficiency and flux were capable of maintaining for 200 separation processes. This work paved the way for designing and constructing economical and practical oil-water separation equipment for industrial application.