The state of the solution-membrane interface during ion transport across an ion-exchange membrane

Y. Oren, A. Litan

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

A cation-exchange membrane, placed between two identical solutions of Na+ and Ca2+ ions and originally equilibrated with them, is found to undergo a significant decrease in its Ca2+ equivalent fraction upon passage of an electric current. The transport number of the two ions also show a strong dependence on current density. A theoretical evaluation of the experimental results, based on the Nernst unstirred layer model, leads to the conclusion that there is no local equilibrium at the solution-membrane interface. This conclusion contrasts with the common assumption that, at an interface between two phases, local equilibrium is maintained even when there is matter transport across the interphase boundary. The Butler-Volmer equations which are used in electrode kinetics are shown to be applicable to the solution-membrane interface, especially as a frame for a qualitative discussion of deviations from local equilibrium.

Original languageEnglish
Pages (from-to)1805-1811
Number of pages7
JournalJournal of Physical Chemistry
Volume78
Issue number18
DOIs
StatePublished - 1 Jan 1974
Externally publishedYes

ASJC Scopus subject areas

  • General Engineering
  • Physical and Theoretical Chemistry

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