Electrokinetic Properties of Nafion 117 in NaCL+KCl Solutions

The applicability of the extended Nernst-Planck equation with the homogeneous distribution of ions and the capillary model (the Boltzmann distribution of ions) to the description of electrokinetic phenomena in the system Nafion 117|0.1 M mixture of NaCl and KCl has been discussed. It has been found that only the capillary model can reasonably describe those phenomena, simultaneously preserving the Onsager reciprocity relation. The extended Nernst-Planck equation gives unsatisfactory results by either strongly breaking the reciprocity relation or, assuming the reciprocity relation (_i must be 1), leading to large discrepancies between the hydrodynamic permeability and the electrical conductivity. The interpretation of _i in terms of the capillary model has been given. _i < 1 for counterions and _i > 1 for coions result from the radial concentration profiles of those ions and of the convective velocity. The dependence of _i on the kind of acting force has been proved.