THE ANTI-FOULING ACTION OF POLYMERS PREADSORBED ON ULTRAFILTRATION AND MICROFILTRATION MEMBRANES

Preadsorption of hydrophilic polymers on hydrophobic ultrafiltration membranes can reduce the susceptibility of the modified membranes to protein fouling. The mechanisms of this anti-fouling action were investigated. Polysulfone and nuclear track-etched membranes with different average pore diameters were hydrophilized by preadsorption of two water-soluble polymers. The fouling of the unmodified and modified membranes due to filtration of a whey protein solution or to adsorption of the whey protein at the membrane surface was characterized by flux measurements and by electron microscopy. Adsorption of protein at the pore walls of ultrafiltration membranes, resulting in the narrowing of pores, is prevented by partly sealing off the pore entrances by polymer molecules presorbed at the external membrane surface. The observed blockage of pores of microfiltration membranes cannot be averted by the preadsorption technique.