The desalination of dilute NaCl solutions with heterogeneous Russian commercial and modified ion-exchange membranes was studied in a laboratory cell imitating desalination channels of large-scale electrodialysers. The modification was made by casting a thin film of a Nafion-type material on the surface of cation-exchange membrane, and by processing with a strong polyelectrolyte the surface of anion-exchange membrane. It was shown that the modifications resulted in an increase of mass transfer coefficient and in a decrease in water splitting rate, both by up to 2 times. The effect of mass transfer growth is explained by higher surface hydrophobicity of the modified membrane that enhances electroconvection. The decrease in water splitting rate in the case of cation-exchange membrane is due to homogenization of its surface layer. In the case of anion-exchange membrane the effect is due to grafting of quaternary ammonium bases onto the original membrane surface layer. The suppression of water splitting favors development of electroconvection. In turn, intensive electroconvection contributes to deliver salt ions to membrane surface and thus reduces water splitting. 1. Introduction The applications of electrodialysis (ED) for water recovery in hybrid systems with RO [1] and in near zero liquid discharge (ZLD) systems [2], for ultrapure water production [3, 4], and for salt production from sea water [5] are some examples of successful use of this process, characterized by high economic and ecological effectiveness [6]. Desalination/deionization of dilute solutions is one of the largest ED applications [6, 7]. However, the process rate in this case is limited by the delivery of electrolyte from bulk solution to the membrane interface. This delivery occurs mainly as electrolyte diffusion while the contribution of forced convection is vanishing when approaching the interface [8–10]. The usage of intensive current modes might be of practical interest, since it can significantly raise the ED process rate [6, 10]. The latest researches [10–12] show that one of the most promising ways of reducing diffusion limitations and enhancing the ED rate is the stimulation of current-induced convection, namely electroconvection. Electroconvection occurs as volume transport under the effect of an electric field imposed through the charged solution, in particular, through the electrical double layer (EDL). In the case where the space charge region (SCR) remains quasiequilibrium, electroconvection occurs as classical electroosmotic flow, named electroosmosis of the first kind
References
[1]
Y. Zhang, K. Ghyselbrecht, B. Meesschaert, L. Pinoy, and B. Van der Bruggen, “Electrodialysis on RO concentrate to improve water recovery in wastewater reclamation,” Journal of Membrane Science, vol. 378, no. 1-2, pp. 101–110, 2011.
[2]
Y. Oren, E. Korngold, N. Daltrophe et al., “Pilot studies on high recovery BWRO-EDR for near zero liquid discharge approach,” Desalination, vol. 261, no. 3, pp. 321–330, 2010.
[3]
J. Wood, J. Gifford, J. Arba, and M. Shaw, “Production of ultrapure water by continuous electrodeionization,” Desalination, vol. 250, no. 3, pp. 973–976, 2010.
[4]
V. I. Zabolotsky, V. V. Nikonenko, N. D. Pismenskaya, and A. G. Istoshin, “Electrodialysis technology for deep demineralization of surface and ground water,” Desalination, vol. 108, no. 1–3, pp. 179–181, 1997.
[5]
Y. Tanaka, R. Ehara, S. Itoi, and T. Goto, “Ion-exchange membrane electrodialytic salt production using brine discharged from a reverse osmosis seawater desalination plant,” Journal of Membrane Science, vol. 222, no. 1-2, pp. 71–86, 2003.
[6]
H. Strathmann, “Electrodialysis, a mature technology with a multitude of new applications,” Desalination, vol. 264, no. 3, pp. 268–288, 2010.
[7]
Y. Tanaka, Ion Exchange Membranes: Fundamentals and Applications, vol. 12 of Membrane Science and Technology, Elsevier, Amsterdam, The Netherlands, 2007.
[8]
K. S. Spiegler, “Polarization at ion exchange membrane-solution interfaces,” Desalination, vol. 9, no. 4, pp. 367–385, 1971.
[9]
P. D？ugo？ecki, B. Anet, S. J. Metz, K. Nijmeijer, and M. Wessling, “Transport limitations in ion exchange membranes at low salt concentrations,” Journal of Membrane Science, vol. 346, no. 1, pp. 163–171, 2010.
[10]
V. V. Nikonenko, N. D. Pismenskaya, E. I. Belova et al., “Intensive current transfer in membrane systems: modelling, mechanisms and application in electrodialysis,” Advances in Colloid and Interface Science, vol. 160, no. 1-2, pp. 101–123, 2010.
[11]
I. Rubinstein and B. Zaltzman, “Electro-osmotically induced convection at a permselective membrane,” Physical Review E, vol. 62, no. 2, pp. 2238–2251, 2000.
[12]
J. Balster, M. H. Yildirim, D. F. Stamatialis et al., “Morphology and microtopology of cation-exchange polymers and the origin of the overlimiting current,” Journal of Physical Chemistry B, vol. 111, no. 9, pp. 2152–2165, 2007.
[13]
S. S. Dukhin, “Electrokinetic phenomena of the second kind and their applications,” Advances in Colloid and Interface Science, vol. 35, no. C, pp. 173–196, 1991.
[14]
N. A. Mishchuk and P. V. Takhistov, “Electroosmosis of the second kind,” Colloids and Surfaces A, vol. 95, no. 2-3, pp. 119–131, 1995.
[15]
N. A. Mishchuk, “Concentration polarization of interface and non-linear electrokinetic phenomena,” Advances in Colloid and Interface Science, vol. 160, no. 1-2, pp. 16–39, 2010.
[16]
S. S. Dukhin and N. A. Mishchuk, “Intensification of electrodialysis based on electroosmosis of the second kind,” Journal of Membrane Science, vol. 79, no. 2-3, pp. 199–210, 1993.
[17]
S. J. Kim, S. H. Ko, K. H. Kang, and J. Han, “Direct seawater desalination by ion concentration polarization,” Nature Nanotechnology, vol. 5, no. 4, pp. 297–301, 2010.
[18]
E. D. Belashova, N. A. Melnik, N. D. Pismenskaya, et al., “Overlimiting mass transfer through cation-exchange membranes modified by NAFION film and carbon nanotubes,” Electrochimica Acta, vol. 59, pp. 412–423, 2012.
[19]
N. D. Pismenskaya, V. V. Nikonenko, N. A. Melnik, et al., “Evolution with time of hydrophobicity and microrelief of a cation-exchange membrane surface and its impact on overlimiting mass transfer,” The Journal of Physical Chemistry B, vol. 116, no. 7, pp. 2145–2161, 2012.
[20]
M. Z. Bazant and O. I. Vinogradova, “Tensorial hydrodynamic slip,” Journal of Fluid Mechanics, vol. 613, pp. 125–134, 2008.
[21]
N. D. Pismenskaya, E. I. Belova, V. V. Nikonenko et al., “Lower rate of H+(OH-) ions generation at an anion-exchange membrane in electrodialysis,” Desalination and Water Treatment, vol. 21, no. 1–3, pp. 109–114, 2010.
[22]
E. I. Belova, G. Y. Lopatkova, N. D. Pismenskaya, V. V. Nikonenko, C. Larchet, and G. Pourcelly, “Effect of anion-exchange membrane surface properties on mechanisms of overlimiting mass transfer,” Journal of Physical Chemistry B, vol. 110, no. 27, pp. 13458–13469, 2006.
[23]
G. Z. Nefedova, Z. V. Klimov, G. S. Sapozhnikov, and Katalog, “Ionitovye membrany” (Russian), M: NIITEKhIM, 1977.
[24]
R. Simons, “Electric field effects on proton transfer between ionizable groups and water in ion exchange membranes,” Electrochimica Acta, vol. 29, no. 2, pp. 151–158, 1984.
[25]
V. I. Zabolotsky, N. V. Sheldeshov, and N. P. Gnusin, “Dissociation of water molecules in systems with ion-exchange membranes,” Russian Chemical Reviews, vol. 57, pp. 801–808, 1988.
[26]
N. D. Pismenskaya, Y. A. Fedotov, V. V. Nikonenko, et al., Patent 2008141949 Russian Federation, B 01D71/60 (2006.01), B01D7/06 (2006.01). Method of ion exchange membrane preparation, Filing date 22.10.2008, Issue date 27.04.2010.
[27]
N. P. Berezina, S. V. Timofeev, and N. A. Kononenko, “Effect of conditioning techniques of perfluorinated sulphocationic membranes on their hydrophylic and electrotransport properties,” Journal of Membrane Science, vol. 209, no. 2, pp. 509–518, 2002.
[28]
N. P. Berezina, N. A. Kononenko, O. A. Dyomina, and N. P. Gnusin, “Characterization of ion-exchange membrane materials: properties vs structure,” Advances in Colloid and Interface Science, vol. 139, no. 1-2, pp. 3–28, 2008.
[29]
E. V. Laktionov, N. D. Pismenskaya, V. V. Nikonenko, and V. I. Zabolotsky, “Method of electrodialysis stack testing with the feed solution concentration regulation,” Desalination, vol. 151, no. 2, pp. 101–116, 2003.
[30]
V. V. Nikonenko, N. D. Pismenskaya, A. G. Istoshin, V. I. Zabolotsky, and A. A. Shudrenko, “Description of mass transfer characteristics of ED and EDI apparatuses by using the similarity theory and compartmentation method,” Chemical Engineering and Processing: Process Intensification, vol. 47, no. 7, pp. 1118–1127, 2008.
[31]
N. V. Sheldeshov, V. V. Ganych, and V. I. Zabolotskii, “Transport number of salt ions and water dissociation products in cation and anion-exchange membranes,” Soviet Electrochemistry, vol. 23, pp. 11–15, 1991.
[32]
N. P. Gnusin, N. P. Berezina, N. A. Kononenko, and O. A. Dyomina, “Transport structural parameters to characterize ion exchange membranes,” Journal of Membrane Science, vol. 243, no. 1-2, pp. 301–310, 2004.
[33]
V. I. Zabolotsky and V. V. Nikonenko, “Effect of structural membrane inhomogeneity on transport properties,” Journal of Membrane Science, vol. 79, no. 2-3, pp. 181–198, 1993.
[34]
V. V. Nikonenko, N. D. Pis'menskaya, and E. I. Volodina, “Rate of generation of ions H+ and OH- at the ion-exchange membrane/dilute solution interface as a function of the current density,” Russian Journal of Electrochemistry, vol. 41, no. 11, pp. 1205–1210, 2005.
[35]
I. Rubinstein and B. Zaltzman, “Extended space charge in concentration polarization,” Advances in Colloid and Interface Science, vol. 159, no. 2, pp. 117–129, 2010.
[36]
M. A.-K. Urtenov, E. V. Kirillova, N. M. Seidova, and V. V. Nikonenko, “Decoupling of the Nernst-Planck and Poisson equations. Application to a membrane system at overlimiting currents,” Journal of Physical Chemistry B, vol. 111, no. 51, pp. 14208–14222, 2007.
[37]
K. S. Spiegler, “Transport processes in ionic membranes,” Transactions of the Faraday Society, vol. 54, pp. 1408–1428, 1958.
[38]
A. M. Peers, “Membrane phenomena,” Discussions of the Faraday Society, vol. 21, pp. 124–125, 1956.
[39]
F. G. Helfferich, Ion Exchange, McGraw-Hill, New York, NY, USA, 1962.
[40]
J. S. Newman, Electrochemical Systems, Prentice Englewood Cliffs, New York, NY ,USA, 1973.
[41]
M. A. Lévêque, Les Lois de la Transmission de Chaleur par Convection, vol. 12-13 of Annales des Mines, Memoires, 1928.
[42]
R. A. Robinson and R. H. Stokes, Electrolyte Solutions, Butterworths, London, UK, 1968.
[43]
V. I. Zabolotsky, V. V. Nikonenko, N. D. Pismenskaya et al., “Coupled transport phenomena in overlimiting current electrodialysis,” Separation and Purification Technology, vol. 14, no. 1–3, pp. 255–267, 1998.
[44]
J. H. Choi, H. J. Lee, and S. H. Moon, “Effects of electrolytes on the transport phenomena in a cation-exchange membrane,” Journal of Colloid and Interface Science, vol. 238, no. 1, pp. 188–195, 2001.
[45]
Y. Tanaka, “Water dissociation reaction generated in an ion exchange membrane,” Journal of Membrane Science, vol. 350, no. 1-2, pp. 347–360, 2010.
[46]
S. Mafé, P. Ramírez, and A. Alcaraz, “Electric field-assisted proton transfer and water dissociation at the junction of a fixed-charge bipolar membrane,” Chemical Physics Letters, vol. 294, no. 4-5, pp. 406–412, 1998.
