Protein adsorption and deposition onto microfiltration membranes: The roleof solute-solid interactions

The mass of gamma-globulin fouling an Anodisc alumina membrane with a nomin al pore diameter of 0.1 mu m has been measured at several concentrations an d pHs, This fouling resulted from filtering through the membrane in a conti nuous recirculation device. The low-concentration fouling can be attributed mainly to adsorption. The complete concentration dependence of fouling mas s has been obtained and fitted to a Freundlich heterogeneous isotherm, from which the pH dependence of active fouling sites and energies has been also obtained. Adsorption is studied as a function of the electrostatic forces between the solute and the membrane. A sharp maximum in the adsorbed mass f or zero electrostatic force is observed. At high concentrations, accumulati on plays a relevant role at alkaline pH, as confirmed by flux decay experim ents, retention measurements, and AFM (atomic force microscopy) pictures. ( C) 2000 Academic Press.