Mobility of Counter Ion in Ion Exchange Membrane

Studies on Permselectivitty hrough Ion Exchange Membrane (III)

Abstract

Mobilities of counter ions in exchange membranes were measured by newly devised electrophoretic apparatus. In this case, two different methods were used. A first method was a direct one, by which electrophoretic distance of counter ions was measured by using²² Na and³⁶ Cl isotopes. A second method was an indirect one, by which the mobility of counter ion was calculated from its transport number, ionic concentration in membrane and specific conductance. The results obtained were as follows:
1. In general, the mobility of the counter ion could be estimated by the second indirect method, since the value obtained by this method approximated to that of the direct method in case the same kind of membrane was used.
2. The mobility of counter ions in the membranes was lower than that in aques solution, and the value decreased to about 1/10 of that in aqueous solution for univalent ions excluding hydroion and hydroxidion, and it also decreased to about 1/20-1/50 for divalent ions.
3. The great decrease in the mobility of divalent ions in the membrane was derived from the fact that the affinity of divalent ions for functional group in the membrane was greater than that of univalent ions.