Electrokinetic regimes of weakly conducting liquids under conditionsof oxidation-reduction process
DOI:
https://doi.org/10.17308/kcmf.2026.28/13970Keywords:
Electroconductivity, numerical simulation, diffusion, dissociation, recombination, voltage-current characteristicAbstract
Objectives: The purpose of the work is mathematical modeling of the transport processes and interaction of ions in a weakly conducting liquid placed between two flat metal electrodes under conditions of a redox process.
Problem statement: The main mechanisms described within the proposed physical and mathematical model are the diffusion, electromigration, recombination, and dissociation. The presence of a potential difference between the electrodes causes the electric field generated in the liquid to displace ions resulting from the dissociation of ion pairs. This leads to concentration polarization, i.e. the accumulation of ions near oppositely charged electrodes and the formation of concentration boundary layers. Ions in direct contact with the electrodes are neutralized back into ion pairs, the behavior of which is described by a separate transport equation. Depending on the potential difference applied to the electrodes, two conductivity regimes are observed in the system. At low electric field strengths, the current is maintained due to the neutralization of ions at the electrodes because of rapid dissociation and recombination in the near-electrode regions. In this case, the ions do not diffuse very far from the electrodes. In turn, at high intensities, the electric field energy is sufficient to drive ion migration across the entire interelectrode space. Thus, at low potential differences, current flow is limited by the intensity of recombination and dissociation, while at high potential differences, it is limited by the rate of ion transfer from the one electrode to other. This circumstance is evident in the current-voltage characteristics, which have multiple inflection points in the initial sections. However, as the slow stage of electrical conductivity passes, the current-voltage characteristic becomes linear.
Conclusions: The calculation results allow us to conclude that the varying values of the kinetic coefficients and the electrical conductivity coefficient allows independent adjustment of the regions of the current-voltage characteristics responsible for a particular regime of current flow
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