Studies with nickel phosphate membranes: evaluation of charge density and test of recently developed theory of membrane potential

The preparation of polystyrene-based nickel phosphate membrane at different pressures with varying amounts of material has been described. In order to understand the mechanism of transport of ions, membrane potential measurements were carried out using different concentrations of 1:1 electrolyte (KCl, NaCl and LiCl) solutions and also to evaluate various membrane parameters controlling the transport phenomena. Teorell, Meyer and Sievers (TMS) method was used for the estimation of the thermodynamically effective fixed charge density of membranes. The data were then utilized to calculate membrane potential using the extended TMS theory. It was interesting to note that the theoretical predictions were borne out quite satisfactorily with experimental results. scanning electron microscope (SEM) micrographs of the membranes have also been presented.