Ionic environmental effect on the time-dependent characteristics of membrane potential in a bipolar membrane

The membrane potential characteristics of a bipolar membrane are discussed in an examination of the contribution of an intermediate phase to time-depe ndent behavior. Bipolar membranes, which consist of a poly(sulfone) base po lymer with a quaternary amino group and a poly(styrene-co-divinylbenzene) c ation-exchange membrane, were prepared in this study. The membrane potentia ls in various external concentration differences, the facing directions of the membrane, and the external electrolyte solutions were measured as a fun ction of time. In this study, the time course of the membrane potential was simulated by using the equation based on the Teorell-Meyer-Sievers theory and by assuming the concentration in the intermediate phase, which is much higher or lower than that in the external solution. The membrane facing dir ection and the intermediate phase condition will alter the direction of the membrane potential change. The intermediate phase in a bipolar membrane se ems to act as an alteration barrier for the membrane potential according to the membrane facing direction. (C) 2001 Academic Press.