In a number of recent studies, the authors derived and substantiated a formula for calculating the theoretical current voltage curve (CVC) of electromembrane systems (EMS). This formula was created for the flow cell of desalination of the electrodiaysis apparatus formed by an anion exchange (AEM) and a cation exchange membranes (CEM) in the potentiodynamic mode based on the charge conservation law. In this paper, the formula for the CVC (I –V characteristic) is investigated, its physical meaning, and the contribution of various factors to the CVC are revealed. A new simplified formula is proposed for calculating CVC, stable with respect to rounding errors. The critical values of the current density were determined and the current voltage curve was divided into separate sections. In the article, we showed that for characteristic values of the average flow rate of the electrolyte solution, the initial concentration in all sections of the CVC, the contribution of the convective current is small. The main role belongs to the electromigration (ohmic) current, especially in the overlimiting sections of the current – voltage curve. The contribution of the diffusion current in limiting and underlimiting sections is quite significant, although less than the ohmic current.
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