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.