The electrodialysis of electrolyte solutions of multi-charged cations

• The electrodialysis of electrolyte solutions of multi-charged cations was studied.
• The relation between hydrogen and ionic bonds was investigated in ion transport.
• The dependence of fluxes of cations on their charges has been investigated.
• Asymmetric concentration polarization of cation-exchange membrane was applied.
• The generation of hydrogen ions and their fluxes were studied.

The quantum chemical calculation of the structure of ion exchange membrane in the form of differently charged cations was performed. The contribution of ionic and hydrogen bonds to the activation energy during the ion transport was investigated. The obtained results show that the energy of ionic bond increases with increasing the charges of cations while the energy of hydrogen bond remains the same. In singly charged cation, the hydrogen bonding plays the determining role in the ion transport, in doubly charged cation the energy of ionic bond is half of the energy of hydrogen bond and hence electrostatic interaction also has a significant role in the transport of ions. For triply charge cation, both ionic bond and hydrogen bond energies are of comparable values and hence they equally contribute to the magnitude of the potential barrier in the transport of ions through membrane. To see these effects practically, the electrodialysis of electrolyte solutions of differently charged cations was studied and their fluxes were investigated. Fluxes of cations through cation exchange membrane in the electrodialysis of electrolyte solutions of multi-charged cations were found to decrease with increasing charges. The generation of hydrogen ions on the interface of solution and cation exchange membrane was also studied and interpreted.