Kinetic Parameters of Ion-Exchange Membrane in Amino Acid Solutions

Kinetic parameters of amino acid cations in an MK-40 ion-exchange membrane are calculated from the conductivity data. A theoretical quantum-chemical analysis of experimental activation energies for conduction suggests a mechanism of elementary act of transport of amino acid cations in the membrane.     

Irreversible dissociation of water molecules on the ion-exchange membrane-electrolyte solution interface in electrodialysis

The fluxes of hydrogen ions through the cation-exchange membrane and hydroxyl ions through the anion-exchange membrane in the electrodialysis were measured using the method of selective polarization. The experiments, which were conducted in a wide range of current densities, enabled us to obtain the results of ionic transport different from the literature data and to explain them on the basis of chemical reactions proceeding in the system. It is shown that a decrease in the hydration of ionogenic groups intensifies the ionic fluxes of the medium in the electrodialysis.     

Ionic Transport in Electrodialysis of Ammonium Nitrate

During the electrodialysis of ammonium nitrate solution, the fluxes of salt ions pass through the maximum, which is observed near the limiting current, with increasing current density. A decrease in the flux of ammonium ions at the overlimiting current densities is caused by the effect of competitive transport of solution ions and by the formation of weak NH₃ ? H₂O electrolyte due to the alkalization of solution layer adjacent to the cation-exchange membrane in the desalination channel. A decrease in the flux of nitrate ions in the overlimiting current modes is caused by a change in the composition and catalytic activity of the functional groups of anion-exchange membrane towards the dissociation of water molecules due to the effect of ammonium ions.     

Transport of hydrogen and hydroxyl ions through ion-exchange membranes under overlimiting current densities

A direct method is suggested for measurement of fluxes of hydrogen and hydroxyl ions through ion-exchange membranes under overlimiting modes of electrodialysis. Fluxes of hydrogen and hydroxyl ions are measured for different immobilized membrane ions and counterions. The important role of counterions in generation of hydrogen and hydroxyl ions is shown. Exponential decrease in fluxes of hydroxyl or hydrogen ions is established at an increase in the Gibbs energy of counterion hydration.