Study of self-diffusion of alkali metal cations inside a Nafion membrane

A novel radiotracer method, based on the rotating electrode technique used in electrochemistry, was used for the study of the self-diffusion propertie s of ions in ion-exchange membranes; the self-diffusion coefficients of Na and Cs+ ions were determined in a Nafion 117 membrane. The influence of el ectrolyte concentration and temperature was investigated and an important i nfluence of the former was observed. The results indicate that the diffusio n process inside the membrane for Na+ ion depends linearly on the water vol ume fraction. The results for Cs+ may be a sign of stronger interactions th an for Na+ ions with the membrane.