Bi-ionic chloride-nitrate equilibrium in a commercial ion-exchange membrane Original Research Article

Chloride-nitrate equilibrium was studied using the Neosepta ACS® anion-exchange membrane. Ion-exchange isotherm and selectivity coefficient were performed on the basis ofthe Donnan equilibrium and Helfferichʹs equilibrium relationship. Fixed ionic group concentration and water activity coefficients in the membrane were constant for any concentration of the nitrate and chloride ions in the solution. It was shown that the selectivity coefficient is more than unity and that the membrane has a good selectivity for nitrate ions.