Polyaniline (PANI) based novel nanocomposites have been fabricated using a simple sol–gel method.

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Transport studies have been carried out across a newly synthesized inorganic-organic nanocomposite membrane. Membrane potential measurements have been measured in various monovalent electrolyte environments at different concentrations to analyse the relationship between transport properties and fixed charge concentration of the membrane. The charge densities were found to follow the order K ? [ Na ? [ Li ?. The counter-ion transport number, ionic mobility ratio and permselectivity of the nanocomposite membrane have also been calculated which reveal that the inorganic-organic nanocomposite membrane shows a higher selectivity towards K ? ions; however, the selectivity decreases with decrease in dilution for all monovalent electrolytes tested. These membranes were comprehensively characterized for their physicochemical properties, morphology, molecular interactions and crystallinity by sophisticated techniques. The ionexchange capacity, volume void porosity and water uptake of the membrane were found to depend on the polystyrene content in the membrane phase and these properties decreased with increase in the amount of polymer (15-35 % by mass). Moreover, membrane containing 25 % of polystyrene exhibited good selectivity along with moderate ion-exchange capacity, which may be used for their application in electro-driven separation at high temperatures or for other electrochemical processes. Keywords Cobalt carbonate nanocomposite Á Transport number Á Permselectivity Á Physicochemical properties Á Tasaka, and Kobatake methods Á Fixed charge density List of symbols and abbreviations c 1 , c 2 Concentrations (mol/L) of the monovalent electrolyte in the lower and higher concentration sides of the membrane, respectively C Average electrolyte concentration (mol/L) SEM Scanning electron microscope XRD X-ray diffraction D Crystallite size b Full width at half-maximum (FWHM) h Diffraction angle (°) W m c Water content in terms of water concentration (mol/L) w w Wet membrane weight (g) w d Dry membrane weight (g) s m Volume void porosity of the membrane q w Density of water (g/cm 3) q d Density of the dry membrane w m Membrane potential (mV) t-app Transparent transport number of anion t m þ Counter-ion transport number in the membrane phase t ? Transport number of the cation in the solution phase

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