ON THE DEPENDENCE OF THE PARAMETERS OF ADSORPTION OF A MICROPOROUS MEMBRANE ON THE METHANOL CONTENT OF LICL WATER-METHANOL SYSTEMS

Two neutral microporous membranes made from polycarbonate are studied within the framework of the Stern model for the electric double layer inside a microcapillary pore, when diluted water-methanol solutions of LiCl are pushed through the membrane. The dependence of their adsorbed charges on concentration is studied and the free energy of specific adsorption and the maximal number of sites accessible to the anions are evaluated. The number of sites decreases very steeply as the methanol content increases according to a higher coverage of the solid matrix surface with methanol than with water. The molar Gibbs free energy is very similar for both the membranes and implies that specific adsorption is slightly enhanced for a pure solvent. © 1993 Academic Press, Inc.