Studies with model membranes Part IX. Evaluation of the thermodynamic effective fixed charge density and permselectivity of parchment supported cobalt tungstate and mercuric chromate membranes

Abstract

Thermodynamic effective fixed charge densities of cobalt tungstate and mercuric chromate parchment supported membranes were evaluated by a number of methods particularly those of Teorell-Meyer-Sievers [19]. Altug and Hair [23] and the most recent one of Kobatake et al. [24, 27] based on the thermodynamics of irreversible processes. The value of the permselectivity was also obtained for the two membranes based on Kobatake et al.'s procedure. Kobatake et al.' equation was used under two limiting conditions of concentration of electrolyte solution, namely (1) in the concentrated range, and (2) in the dilute range. The charge densities obtained under these conditions namely θ c and θ d were found to differ ( θ c =1/2 θ d ), but it was interesting to note that θ c values were more closer to those of the TMS values. The theoretical predictions for membrane potential using Kobatake et al.'s equation are borne out quite satisfactorily by our experimental results for both membranes.