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

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 transport in ion-selective membranes. The results from constant-resistance membranes, e.g. membranes with unperturbed negative site concentration profiles, showed that tridodecylamine behaved as a carrier for H+, and there was no evidence for proton hopping from stationary carriers. In addition, the experimental outcome supported the assumption of a failure of the Donnan exclusion principle at very low pH levels in these membranes. The results from membranes containing the Na+ carrier illustrated the significant concentration polarization of ionic species, which was related to significant changes in bulk membrane resistance.