Evaluation of some interactions in permselective membranes

Abstract

The number of moles of water (f3) accompanying ion transport, following passage of 1 faraday of current across three cation selective membranes, one of high water content and the other two of low water content, has been measured at 25°u sing 0.01 N solutions of NaCl, RbCl, or CsCl. Also, specific conductance, counterion selfdiffusion coefficient, and hydrodynamic permeability of the membranes have been determined. These data and other equilibrium parameters like water content and exchange_capacity have been used to derive values for the Stefan-Maxwell diffusivity coefficients, A*i, Ai, As, and Du, from a few relations given by Scattergood and Lightfoot. The diffusivity coefficient A*i was the lowest (i.e., the interaction between species 1* and 1 was the highest) in the case of membranes of low water content in which f3 showed little dependence on the current density used in its measurement. In the case of high water content membrane, fe was dependent on the current density employed during electrolysis. At low current densities, i3 was greater than the quantity of water associated with 1 equivalent of counterion in the membrane phase. With this value of f3, Du assumed negative values. On the other hand, when the limiting value of f3 observed at high current densities_was used in the equations, values obtained for the diffusivity coefficients increased in the order Du < A*i < As < O34• The order of these coefficients for membranes of low water content was A*i < Du < A3 < Du.

Transport Studies with Aqueous Solutions of Urea and Thiourea Across an Ionexchange Membrane

“…Similar results using highly charged membranes have so far not been carried out. Lakshminarayaniah [10] and Tombalakian et al [11] examined the dependence of transport numbers of water in aqueous solutions on current density using ion-exchange membrane. It is expected that the electrical double layer in highly charged membranes would be more sensitive to the change in characteristics depending on the nature of the permeants which would naturally be reflected in transport properties.…”

Electrokinetic Phenomena at the Testosterone/Aqueous Urea Interface

“…Non-equilibrium thermodynamic studies on electrokinetic phenomena have recently been carried out with uncharged and charged membranes [1][2][3][4][5]. However, studies with membranes of biologically important materials are scarce [6].…”