INTERACTION OF PERMSELECTIVE MEMBRANES AND THEIR COUNTER-IONS

For a series of permselective membranes, the influence of counter-ions on resistance, permselectivity, swelling and co-ion content was examined. The size and charge of the counter-ions were respectively varied. Characteristic differences between membranes of similar initial properties were observed and correlated with differences in their structure. Due to the presence of the counter-ions, resistances increased in many cases by several orders of magnitude, the sign of permselectivity was often inverted, and very strong deswelling was often observed. The co-ion content increased with concentration of the external solution and conductivity and inverted permselectivity of the membranes increased with it. It was found that small, hydrated ions affect the membrane properties less than large ones which are presumably less hydrated. The mechanism of these processes is discussed. © 1968.