IONIC BEHAVIOR AND MEMBRANE-POTENTIAL IN WEAKLY AMPHOTERIC POLYMER MEMBRANES

The membrane potential of a weakly amphoteric polymer membrane was mea sured by varying the dissociation state of the dissociative groups wit hin the membrane through control of the pH of the outer aqueous soluti on, and the effective charge density of the membrane was evaluated. On the basis of a modification of the Teorell-Meyer-Sievers equation, we concluded that the difference between the charge densities of the pos itively and negatively charged dissociative groups seemed to play an i mportant role in the permeation behaviour through the membrane. From t he results of a study of the potentiometric behaviour of aqueous polya mphoteric solutions, it was confirmed that the ratio of the effective charge density to the net value could be estimated to be the same as t hat found previously. (C) 1996 Elsevier Science Ltd.