Formation and characterization of poly(acrylonitrile)/Chitosan composite ultrafiltration membranes

Abstract

The Poly(acrylonitrile) (PAN)/Chitosan composite ultrafiltration membranes were prepared by filtration of Chitosan solution through PAN base membrane and subsequent curing and treatment with NaOH. The formation of Chitosan layer on the surface as well as pore walls of PAN base membrane was characterized by different techniques. Fourier transform infrared-attenuated total reflectance, X-ray photoelectron spectroscopy and scanning electron microscopy studies indicated the formation of Chitosan layer on the surface, whereas determination of pure water permeation, pore size distribution and molecular weight cut off indicated the reduction in pore size due to formation of Chitosan layer on the pore walls of PAN base membrane. It was further observed that these composite membranes had sharper molecular weight cut off as well as narrower pore size distribution than the corresponding base membrane. The reduction in negative zeta potential of PAN base membrane at pH 9.0 and observation of positive zeta potential at pH 5.0 with composite membranes also confirmed the formation of Chitosan layer on the pore walls of base membrane. The composite membranes were found to be stable in aqueous medium and showed reduction in pure water fluxes measured after filtration of aqueous acidic (pH 3.0) and basic (pH 11.0) solution, which was attributed to the swelling of Chitosan layer.