The improved oil/water separation performance of cellulose acetate-graft-polyacrylonitrile membranes

Polyacrylonitrile (PAN) membrane possessed high water flux but poor antifouling property, whereas cellulose acetate (CA) membrane displayed superior antifouling property but low flux in ultrafiltration operations. In this study, to achieve both high permeation flux and fouling resistance, a novel membrane material was synthesized through grafting PAN onto CA powder via free radical polymerization. The synthesized CA-graft-PAN (CA-g-PAN) copolymer was employed to fabricate asymmetric ultrafiltration membranes by phase inversion method. It was found that CA-g-PAN membranes exhibited remarkably high water permeability (about 100 times) than CA membrane. Ultrafiltration experiments also demonstrated that CA-g-PAN membranes have excellent oil-fouling-resistance ability even under higher operation pressure and higher oil concentration in oil/water emulsion. Most of the deposited oil droplets on CA-g-PAN membrane surfaces can be easily washed away by simple hydraulic washing, and the fluxes of CA-g-PAN membranes were nearly completely recovered. After three times oil/water emulsion ultafiltration, the flux of feed solution was also kept at a relative high level of about 110 L/(m2 h), indicating good oil/water separation performance of CA-g-PAN membranes.