775 ISSN 1023-1935, Russian Journal of Electrochemistry, 2018, Vol. 54, No. 10, pp. 775–781. © Pleiades Publishing, Ltd., 2018. Original Russian Text © S.V. Zyryanova, D.Yu. Butyl’skii, S.A. Mareev, N.D. Pis’menskaya, V.V. Nikonenko, G. Pourcelly, 2018, published in Elektrokhimiya, 2018, Vol. 54, No. 10, pp. 885–892. Effect of Parameters of Pulsed Electric Field on Average Current Density through Nafion 438 Membrane in Electrodialysis Cell S. V. Zyryanova a, *, D. Yu. Butyl’skii a , S. A. Mareev a , N. D. Pis’menskaya a , V. V. Nikonenko a , and G. Pourcelly b a Kuban State University, Krasnodar, 350040 Russia b European Institute of Membranes, UMR 5635, University of Montpellier, ENSCM, CNRS, CC047, Montpellier, Cedex 5, 34095 France *e-mail: zyryanova.s.v@yandex.ru Received June 29, 2017; in final form, February 25, 2018 Abstract—Pulsed electric fields (PEF) have been used to advantage in electroplating for more than half a cen- tury. Recently, interest has increased in the application of these electric modes in the membrane processes. In this work, the effect of parameters (potential, frequency of current, and duty cycle) of pulsed current mode on the average current density in the electrodialysis cell is studied. For this purpose, the plots of current vs. time were measured in the mode of pulsed potential drop on a Nafion 438 (Nafion TM N438) cation-exchange membrane. It is shown that the largest gain in the current density of 33% can be attained by varying param- eters of PEF. Keywords: pulsed electric field, pulsed current mode, current density, ion-exchange membrane, electrodialysis DOI: 10.1134/S1023193518100075 INTRODUCTION Pulsed currents, or more broadly, pulsed electric fields (PEF) have long been used effectively in electro- plating to improve the physicochemical and func- tional properties of the coatings (to enhance the adhe- sion of coating to the substrate, reduce porosity, increase hardness and wear resistance, raise corrosion resistance, etc. [1–3]. In recent years, these electrical modes began to be applied in the practice of membrane processes [4]. In this case, the main effects are an increase in the mass transfer rate [5, 6], and, perhaps of greater importance to the practice of electrodialysis (ED), a decrease in the membranes fouling rate [4, 7–9]. In addition, in the pulsed mode, the rate of water dissociation at the membrane/depleted solution interface decreases, and it becomes possible to operate at higher voltages avoid- ing problems associated with a change in the pH value of desalted and concentrated solutions [4, 5, 10, 11]. Thus, there are reasons to propose that the main diffi- culties in using ED in intense current modes (sedi- mentation, low current efficiency, and undesirable shift of pH value) can be overcome, at least partially, by using pulsed currents. Back in 2001, Mishchuk et al. [12] supposed that, when the overlimiting pulsed modes are used in ED with the ion-exchange membranes, the gain in the mass transfer is explained by the fact that during a pause, the electroconvective vortices do not decay completely, but continue to rotate due to the inertia force. The numerical modeling performed by Uzde- nova et al. [13] showed that this effect does occur, but more important is the formation of new vortices, when the voltage is re-applied. It was shown that inhomoge- neous concentration field induces an effect similar to the effect of electrically or geometrically heteroge- neous surface. This causes the formation of spatially heterogeneous electric field that promotes the electro- convection. From the practice of electroplating, it is known that when the pulsed current is used, the mass transfer rate increases with increasing pulse frequency up to 500 Hz [14]. At higher frequencies, the efficiency of this mode decreases, because the parasitic charging–discharging process in the electric double layer becomes notice- able. In [6], it was shown that in the electrodialysis of dilute electrolyte solutions in the sub-limiting current mode, the regularities of the gain in the mass transfer rate agree with the results obtained in the electroplat- ing: the mass transfer rate increases with increasing pulse frequency at a constant average voltage. The experimental and calculated results showed that the