VALIDATION OF CARRIER-MEDIATED TRANSPORT OF H-SITE MEMBRANES( AND NA+THROUGH MOBILE)

The response of membranes containing neutral ion carriers of either H or Na+ to an externally-applied potential step was investigated using previously developed techniques for the analysis of charge and mass t ransport in ion-selective membranes. The results from constant-resista nce membranes, e.g. membranes with unperturbed negative site concentra tion profiles, showed that tridodecylamine behaved as a carrier for H, and there was no evidence for proton hopping from stationary carrier s. In addition, the experimental outcome supported the assumption of a failure of the Donnan exclusion principle at very low pH levels in th ese membranes. The results from membranes containing the Na+ carrier i llustrated the significant concentration polarization of ionic species , which was related to significant changes in bulk membrane resistance .