Fractioning electrodialysis: a current induced ion exchange process

A.H. Galama, G. Daubaras, O.S. Burheim, H. Rijnaarts, J.W. Post

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)

Abstract

In desalination often multi ionic compositions are encountered. A preferential removal of multivalent ions over monovalent ions can be of interest to prevent scaling in the desalination process. Recently, a novel fractionating electrodialysis stack is described by Zhang et al., 2012 (in Sep. purify. Technol. 88). In the present work a small modification to such a stack was made, to create a current induced ion exchange process, in which no longer desalination occurs. This was done by building a membrane stack in which monovalent-selective ion-exchange membranes and standard grade ion-exchange membranes, with similar charge sign (so either anion or cation exchange groups), were placed alternatingly between an anode and a cathode to form a membrane stack. A proof of principle of the fractioning electrodialysis technology is given. Ternary mixtures, with a divalent-monovalent ion ratio similar to seawater, were used as feed water. For a cation and an anion fractioning stack, maximum fractionations of divalent ions were obtained of approximately 90 and 60%. At higher applied current density, ions can be fractionated to a larger extent than at lower applied current density. For both stacks the water recovery was 50%. Coulombic efficiency of both processes decrease rapidly after the start of the experiment. This leads to relatively large volumetric energy consumptions. (C) 2014 Elsevier Ltd. All rights reserved.
Original languageEnglish
Pages (from-to)257-265
JournalElectrochimica Acta
Volume136
DOIs
Publication statusPublished - 2014

Keywords

  • divalent ions
  • seawater desalination
  • membrane
  • monovalent
  • diffusion
  • transport
  • charge
  • nanofiltration
  • permeability
  • polarization

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