Evaluation of charge density and the theory for calculating membrane potential for a nano-composite nylon-6,6 nickel phosphate membrane

Abstract

A new crystalline organic–inorganic nano-composite nylon-6,6 nickel phosphate membrane was synthesised subsequent to which (a) the physico-chemical characteristics of the membrane were evaluated employing FTIR, SEM, EDX, TEM, XRD and porosity measurements, and (b) membrane potential measurements were conducted employing different concentrations (0.0001 ≤ c (M) ≤ 1) of KCl, NaCl and LiCl 1 : 1 electrolyte solutions. The Teorell, Meyer and Sievers (TMS) theoretical method was employed for evaluating the charge density of the synthesised membranes, and the observed data were utilised to calculate membrane potentials using the extended TMS theory. Charge density for 1 : 1 electrolyte solutions was found to decrease in the order KCl > NaCl > LiCl, which is in accordance with a decrease in the size of the cation. The synthesised membrane was found to be cation-selective with the measured membrane potentials found to be positive in all instances, decreasing in the order LiCl > NaCl > KCl, which is in accordance with an increase in the size of the cation for the chosen electrolytes. Observed potential data were used to calculate the transference numbers, mobilities, distribution coefficients, and charge effectiveness of ions and the theoretically calculated potential values were found to be in good agreement with the experimentally observed values.