Poly(isophthalamide) based graft copolymer for the modification of cellulose acetate ultrafiltration membranes and a fouling study by AFM imaging

Abstract

Poly(isophthalamide) based copolymer, poly(isophthalamide)-graft-methacrylamide (PIPA-g-MAA) has been prepared and used to modify the surface and fouling liable properties of the cellulose acetate (CA) membranes. Grafting facilitated the solubility of PIPA in common aprotic solvents and made it available as a potential membrane material for the modification of CA membrane. Compatibility between CA and PIPA-g-MAA in blend membranes was confirmed by a single glass transition temperature, and improved hydrophilicity of the membranes was illustrated by the lower contact angle values. The thermal and mechanical stability of the CA membrane was also improved by the blending with PIPA-g-MAA. The separation efficiency of various commercial proteins by these CA/PIPA-g-MAA blend membranes was studied and found to have improved significantly. The fouling propensity of the membranes was studied using BSA as a model foulant and the resistance arising during different stages of filtration was evaluated using resistance in series model. From the AFM images it could be observed that protein uniformly covers the blend membrane surfaces and non-uniform protein clusters are formed in the CA membranes due to preferential adsorption at specific sites. The irreversible fouling resistance (Rir) could be greatly reduced by the incorporation of the synthesized PIPA-g-MAA in the CA matrix.