PROTEIN ADSORPTION AND FOULING IN CERAMIC ULTRAFILTRATION MEMBRANES

The adsorption of proteins to membrane surfaces can lead to the formation of a fouling layer, which drastically reduces permeate flux and represents a serious impediment to efficient ultrafiltration operations. In this work, the factors influencing permeate flux, adsorption and fouling during crossflow ultrafiltration of bovine serum albumin using microporous alumina membranes with mean pore diameters of 40, 350 and 1000 angstrom have been examined. In general, the permeate flux was observed to be a function of concentration, transmembrane pressure and crossflow velocity as described by classical gel polarization theory. For protein concentrations above 1 g/l, solute rejection was nearly complete even for the 1000 angstrom membranes. At low solute concentrations, rejection increased with decreasing pore size and increasing crossflow velocity. Studies of the flux and rejection dependence on pH, solute concentration, ionic strength, membrane pore size and cleaning procedure, coupled with adsorption studies, indicated that adsorption-related pore plugging plays a significant role in the two larger pore size membranes.