Selective grafting of morphologically modified poly(vinylidene fluoride) ultrafiltration membrane by poly(acrylic acid) for inducing antifouling property

Abstract

Fouling propensity of a membrane depends on water wetting property and interaction of foulants with the surface. Surface initiated polymerization usually leads to the grafting of main membrane forming polymer. Herein, we report a process for the selective grafting of blend component of poly(vinylidene fluoride) (PVDF) membrane, and the effect of morphological feature on the water wetting behaviour and antifouling property. Polymerization of acrylic acid (AA) in contact with a morphologically modified blend membrane of PVDF leads to selective grafting of blend component by PAA chains. Polymerization causes formation of graft copolymer throughout the membrane matrix. Base membrane morphology and grafting time profoundly influence surface roughness, permeate flux and water wetting behaviour of the membranes. Grafting time window of 2–4 h produces membranes with high oil rejection (>99.5%), high flux recovery ratio (>95%) and low flux reduction (30–36%) during recovery of water from surfactant free and surfactant stabilized oil-in-water emulsions. The surface roughness and morphology of the base and grafted membranes are important factors to induce hydrophilic property, which in turn reduces the fouling propensity of the membranes. This work provides an insight regarding the influence of surface roughness on the water wetting behaviour and antifouling property of the membranes.