A mathematical model describing voltammograms and transport numbers under intensive electrodialysis modes

作者：Zabolotskii V I; Lebedev K A^*; Urtenov M Kh; Nikonenko V V; Vasilenko P A; Shaposhnik V A; Vasil'eva V I

来源：Russian Journal of Electrochemistry, 2013, 49(4): 369-380.

DOI：10.1134/S1023193513040149

• electrodialysis
• dissociation
• voltammogram
• transport numbers

A three-layer mathematical model of overlimiting state is developed. A reactive layer with a thickness depending on the current density is introduced into the model. A decrease in the thickness of diffusion layer, which donates the counterions, with increasing current density as a result of electroconvection is also taken into account. A boundary-value problem is formulated within the Nernst-Planck and Poisson's model in the three-layer region with the boundary conditions of constant concentrations in the bulk solution. It is shown that an increase in the reactive layer thickness with increasing current density determines the behavior of effective transport numbers in the overlimiting state of ion-exchange electromembrane system. In the current range under consideration (from 1 to 20 limiting currents), the reactive layer thickness is several tens nanometers and reaches 70 nm at a 100-fold excess over the limiting current. To calculate the voltammograms, the dependence of effective thickness delta(N) of diffusion layer on the current density is required. This dependence can be obtained by solving an inverse problem, from the laser interferometry experiments, or calculated by the Navier-Stokes hydrodynamic model. The model enables one to calculate the distribution of electric field strength, potential, concentrations in the diffusion layers and membrane.

• 出版日期2013-4