The paper presents an analysis of existing methods of membrane separation of solutions on semipermeable and ion-exchange membranes, where their advantages and disadvantages are noted. The objects of study were OFAM-K and OPMN-P nanofiltration membranes and aqueous solutions of potassium sulfate used in the production of mineral fertilizers. The change in the retention coefficient on the near-anode OFAM-K membrane for sulfate ions and on the near-cathode membrane OPMN-P for potassium ions was studied at current densities of 12,82 and 15,38 A/m2 with varying transmembrane pressure. An analysis of the retention coefficient of the OPMN-P cathode membrane for potassium ions with increasing pressure shows its increase by 20–30%, which is probably caused by an increase in the water permeability rate, which causes permeate dilution. In the case of analysis of the retention coefficient for sulfate ions on the anode OFAM-K membrane in the region of low current densities, the retention capacity first decreases with an increase in the transmembrane pressure, and then reaches a constant value with a slight increase at a pressure of 1,5 MPa. At higher current densities, the retention coefficient for sulfate ions on the anode OFAM-K membrane with an increase in transmembrane pressure, as well as on the OPMN-P cathode membrane, for potassium ions increases. The time dependences of the specific output flux are given at transmembrane pressures of 0,75, 1, and 1,5 MPa and current densities of 12,82 and 15,38 A/m2. It is noted that the specific output flux increases on the near-anode OFAM-K membrane, while on the near-cathode membrane OPMN-P it decreases with time, which is due to the transformation of the physical properties of the membranes and boundary layers formed on their working surface. On the near-anode OFAM-K membrane, water permeability increases with time, and on the near-cathode membrane OPMN-P it decreases. The presented data on the desorption of potassium ions and sulfate ions on the near-anode membrane OFAM-K and near-cathode membrane OPMN-P indicate that the desorption of ions decreases with time, and the desorption index of potassium ions on the near-anode OFAM-K membrane is higher, although in the process Electronanofiltration ions are transferred in equivalent ratios.

1. Kozaderova O.A., Niftaliev S.I., Kim K.B. Application of bipolar MB 2 membranes modified with chromium (III) hydroxide for sodium sulfate conversion. News of higher educational institutions. Series: Chemistry and Chemical Technology. 2019. vol. 62. no. 3. pp. 30-36. (in Russian).

2. Kononenko N.A., Demina O.A., Loza N.V., Dolgopolov S.V et al. Theoretical and experimental investigation of the limiting diffusion current in systems with modified perfluorinated sulfocationite membranes. Electrochemistry. 2021. vol. 57. no. 5. pp. 283-300. (in Russian).

3. Yurova P.A., Stenina I.A., Yaroslavtsev A.B. Effect on the transport properties of MK 40 cation exchange membranes modified with perfluorosulfopolymer and cerium oxide. Electrochemistry. 2020. vol. 56. no. 6. pp. 568-573. (in Russian).

4. Shaposhnik V.A., Anisimova N.O., Korovkina A.S. Electrical conductivity of multilayer monopolar ion-exchange membranes. Sorption and chromatographic processes. 2018. vol. 18. no. 3. pp. 346-351. (in Russian).

5. Tsygurina K.A., Rybalkina O.A., Melnikova E.D., Pishevskaya N.D. Total and partial voltage characteristics of anion-exchange membranes in solutions of NaCl and NaH2 PO4. Condensed media and interphase boundaries. 2017. vol. 19. no. 4. pp. 585-595. (in Russian).

6. Kozaderova O.A., Niftaliev S.I., Kim K.B. Ion transfer during ammonium nitrate electrodialysis. Electrochemistry. 2018. vol. 54. no. 4. pp. 416-422. (in Russian).

7. Kharina A.Yu., Eliseev S.Ya. Demineralization of phenylalanine solution by electromembrane methods. Condensed media and interphase boundaries. 2017. vol. 19. no. 1. pp. 126-132. (in Russian).

8. Eliseeva T.V., Kharina A.Yu., Chernikova E.N., Charushina O.E. Demineralization of heterocyclic amino acid solutions by the electromembrane method. Sorption and chromatographic processes. 2021. vol. 21. no. 4. pp. 492-497. (in Russian).

9. Mavletov M.N., Yarullin A.Z., Berezin N.B., Mezhevich Zh.V. Local wastewater treatment of electroplating plants by a combined method using an electrodialysis unit and ion exchange columns. Bulletin of the Technological University. 2019. vol. 22. no. 6. pp. 63-66. (in Russian).

10. Vasilyeva V.I., Saud A.M., Akberova E.M. Separation of water-salt solutions of phenylalanine by electrodialysis using membranes with different mass fraction of sulfocation exchange resin. Sorption and chromatographic processes. 2021. vol. 21. no. 4. pp. 498-509. (in Russian).

11. Chigaev I.G., Komarova L.F. Investigation of nanofiltration and ion exchange as complex methods of natural groundwater purification. Bulletin of the Technological University. 2019. vol. 22. no. 4. pp. 99-102. (in Russian).

12. Vinnitskiy V.A., Chugunov A.S., Ershov M.V. Effect of retentate consumption on membrane separation of binary solutions of sodium, magnesium and calcium chlorides. News of higher educational institutions. Series: Chemistry and Chemical Technology. 2021. vol. 64. no. 10. pp. 46-55. (in Russian).

13. Lazarev S.I., Kovalev S.V., Konovalov D.N., Kovaleva O.A. Analysis of kinetic characteristics of baromembrane and electrobaromembrane separation of ammonium nitrate solution. Izv. vuzov. Chemistry and chemical technology. 2020. vol. 63. no. 9. pp. 28-36. (in Russian).

14. Konovalov D.N., Lazarev S.I., Ryzhkin V.Yu., Kovalev S.V. et al. Design and calculation of an electrobaromembrane apparatus of a flat-chamber type for separation of industrial solutions with an equal area of near-cathode and near-anode membranes. Chemical and oil and gas engineering. 2021. no. 5. pp. 10-13. (in Russian).

15. Abonosimov O.A. Investigation of hydrodynamic permeability of reverse osmotic membranes in solutions of heavy metal salts. Issues of modern science and practice. V.I. Vernadsky University. 2016. vol. 1. no. 59. pp. 187-191. (in Russian).

16. Lazarev S.I., Kovalev S.V., Konovalov D.N., Lua P. Electrochemical and transport characteristics of membrane systems during electron-filtration separation of solutions containing ammonium nitrate and potassium sulfate. Electrochemistry. 2021. vol. 57. no. 6. pp. 355-376. (in Russian).

17. Vladipor: website of CJSC STC Vladipor. Available at: www.vladipor.ru/catalog/show (in Russian).

18. Dytnersky Y.I., Volcheck K.A., Polyanskaya N.B. Separation of multicomponent solutions using reagent ultrafiltration. Desalination. 1991. vol. 81. no. 1-3. pp. 273-279.

19. Swittsov A.A. Introduction to membrane technology. Moscow, Delhi Print, 2007. 208 p. (in Russian).

20. Lua P., Lazarev S.I., Kovaleva O.A., Kovalev S.V. Electrochemical and kinetic characteristics of the process of electromembrane separation of potassium sulfate solution. Izv. vuzov. Chemistry and chemical technology. 2021. vol. 64. no. 8. pp. 107-114. (in Russian).