Covalent Immobilization of Arginine onto Polyacrylonitrile-Based Membrane for the Effective Separation of Oil/Water Emulsion

Membrane technology has been accepted as a very effective approach to purify oily wastewater. However, the serious membrane fouling induced by the adsorption of oily foulants significantly hinders the development of membrane technology in treating oily wastewater. To improve the anti-fouling property and oil/water separation efficiency of membrane, this work reports on the covalent immobilization of short-chain arginine (Arg) molecules onto polyacrylonitrile/polyacrylonitrile- co -poly(glycidyl methacrylate) (PAN/PAN- co -PGMA) blend membrane surface via a ring-opening reaction between epoxy groups and amine groups. It was found that the covalent immobilization of Arg molecules effectively increased the surface hydrophilicity of the membrane, resulting in a significant decrease of the interaction force between the foulants and the membrane surface. This typical characteristic was revealed by the pure water contact angle and the force-extension curve measurements. The Arg-immobilized membranes exhibited much higher separation efficiency against oil/water emulsions than the pristine PAN and PAN/PAN- co -PGMA membranes. Especially when the grafting amount of Arg was 157.3 μg/cm 2 , the oil rejection ratio of an Arg-immobilized membrane was as high as 99.2%. In addition, the flux recovery ratio of the membrane still reached 88.8%, even after two cycle filtrations of pure water and oil/water emulsion. These results indicated that the Arg-immobilized membrane may have practical applications for oil/water emulsion separation.