Transport studies of BSA, lysozyme and ovalbumin through chitosan/polystyrene sulfonate multilayer membrane

We report the fabrication of a novel composite membrane with high flux and good selectivity which may find application in protein separations under ultrafiltration conditions by modifying the surface of a microfiltration membrane (Supor 450, 0.45 μm pore size, polyethersulfone membrane) with a uniform coating of chitosan(CHI)/polystyrene sulfonate(PSS) polyelectrolyte multilayer. The transport of bovine serum albumin (BSA), ovalbumin and lysozyme at their isoelectric point (pI), pH below and above their isoelectric points (pI), through these multilayer membranes have been studied. We observed a dramatic change in the transport behavior of the proteins through these multilayers depending on the number of deposited layers and the solution pH. The transport studies through the composite membranes shows 95% rejection of BSA by a 9-bilayer (bl) CHI/PSS multilayer (permeate flux of 0.49 m3/m2 day) at 10 psi. Ovalbumin showed permeate enrichment and more than 100% of ovalbumin is permeated (permeate flux of 25.7 m3/m2 day) and 98% lysozyme is rejected (permeate flux of 11.7 m3/m2 day) at 10 psi by a 5 bl membrane at pH 8.8. The individual transport studies of ovalbumin and lysozyme indicates that these egg white proteins could be separated using this multilayer system.