Additivity between donnan salt and ion-exchanged salt in the specific conductance of membranes

Abstract

In an amphoteric membrane-single electrolyte system, the total specific conductances of the membrane were separated into two portions, viz., the specific conductances due to Donnan salt and to ion exchange with sites. The specific conductances due to Donnan salt were proportional to the concentration of Donnan salt. The mobilities of Donnan salt were evaluated from the relation between the specific conductance and the concentration. The ion concentrations of two different ionic states within the membrane were also measured in a mixed electrolyte system. The total specific conductances in the mixed electrolyte system were estimated by using the values of mobility obtained in the single electrolyte system. The result showed the appearance of a minimum in the specific conductance-concentration curve. Additionally, in order to confirm the observation, the specific conductances in the mixed electrolyte system were measured. The experimental values were in good agreement with the calculated values. It was conducted that the additivity between Donnan salt and ion exchanged salt in the specific conductances held good in the mixed electrolyte system.