WATER TRANSPORT BEHAVIOR IN NAFION-117 MEMBRANES

The water transport behavior in Nafion 117 cation exchange membrane wa s studied using the streaming potential method. The water transference coefficient of the membranes in the H+ form was found to be 2.6. The results also show that Nafion 117 membranes have a good cation selecti vity performance in HCl solutions within a concentration range between 0.003 and 1N. The water transference coefficients of the membranes eq uilibrated with alkali metal chlorides and alkaline earth metal chlori des solutions were investigated as well. It was found that the water t ransport behavior is related to the surface-charge density, hydration enthalpy of the cations exchanged in the membranes, and water content of the membrane. The effective diameter of the micropore in Nafion 117 was estimated as 0.8 to 1.3 nm.