Electrodialysis of Dilute Solutions: The Influence of pH on the Transport of Salt Ions

N. D. Pis’menskaya
Российский электрохимический журнал
Abstract / Full Text

The solution pH in the desalination channel of an electrodialysis cell is shown to depend on thenature of membranes, the membrane system’s degree of polarization, and the ratio between the areas of cation-exchange and the anion-exchange surfaces. A qualitative correspondence is revealed between the experimentaldata and the equation derived from the system of the Nernst–Planck–Poisson equations, taking into account thewater dissociation at the membrane–solution interface. The appearance of H+ or OH ions in the solution beingdesalinated is shown to result in decelerated mass transfer of salt ions of the like charge across the corresponding membranes. This is caused not only by the competitive transport of salt ions and products of water dissociation, but to the weakening of the exaltation effect of the limiting current as well.