Rate of Generation of Ions H+ and OH− at the Ion-Exchange Membrane/Dilute Solution Interface as a Function of the Current Density

Abstract

Partial currents of water dissociation products through cation- and anion-exchange membranes that form thin desalination channels in electrodialyzers are measured. The investigations are performed in a broad interval of flow rates during desalination of dilute sodium chloride solutions at overlimiting currents. A water dissociation theory, which was developed for bipolar membranes, and a mass transfer theory that allows for the space charge formation at overlimiting currents are used to derive an expression, according to which the rate of generation of the H+ and OH− ions is defined by the ratio of the current density to its critical value at which water starts undergoing discernible dissociation.