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

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 la yer on the surface as well as pore walls of PAN base membrane was character ized by different techniques. Fourier transform infrared-attenuated total r eflectance, X-ray photoelectron spectroscopy and scanning electron microsco py studies indicated the formation of Chitosan layer on the surface, wherea s determination of pure water permeation, pore size distribution and molecu lar 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 obse rved that these composite membranes had sharper molecular weight cut off as well as narrower pore size distribution than the corresponding base membra ne. 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 membra nes also confirmed the formation of Chitosan layer on the pore walls of bas e membrane. The composite membranes were found to be stable in aqueous medi um and showed reduction in pure water fluxes measured after filtration of a queous acidic (pH 3.0) and basic (pH 11.0) solution, which was attributed t o the swelling of Chitosan layer. (C) 1999 Elsevier Science B.V. All rights reserved.