INFLUENCE OF SPACE CHARGE BREAKDOWN ON THE PERFORMANCE OF ELECTROMEMBRANE SYSTEMS

It is known that the existing methods of using electromembrane systems (EMS) do not allow the most efficient water treatment and water treatment at overlimiting current modes, which is why there is a need to determine the operating parameters of electrodialysis plants to prevent complex destructive effects, it is essential limiting mass transfer, and reducing the efficiency of EMS. In addition, in practice, a contradiction is found in practice - an increase in the potential jump in the existing EMS does not provide an intensification of the transfer of salt ions under overlimiting current modes.

The article is devoted to the study of the influence of one of the destructive phenomena - the breakdown of the space charge on the performance of electromembrane systems in highly diluted salt solutions. The aim of this work is a theoretical assessment of the effect of space charge breakdown on the transport of salt ions in electromembrane systems.

A mathematical model based on the Nernst-Planck and Poisson equations has been developed. The process of electrodialysis desalination of a NaCl solution located in a flow chamber between an anion exchange membrane (AEM) and a cation exchange membrane (CEM) is considered. The solution flow is directed from bottom to top. Numerical modeling of the effect of space charge breakdown on EMS performance in highly dilute salt solutions has been carried out.

The new mathematical model and software have been developed for numerical simulation of the effect of space charge breakdown on EMS performance in highly dilute salt solutions.

In this work, using a 2D mathematical model and the formula for the current-voltage characteristic of the desalination channel, the effect of space charge breakdown on the transfer of salt ions in electromembrane systems at various values of the potential jump was determined for the first time. The ranges of currents are determined, which correspond to a high and slight increase in the performance of electromembrane systems, as well as a range of currents in which there is no increase. The obtained results can be used to determine the optimal value of the potential jump according to the criterion of maximum productivity. The results obtained can be applied to the design of industrial EMC to intensify mass transfer and increase productivity.

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