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 language | English |
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Pages (from-to) | 1805-1811 |
Number of pages | 7 |
Journal | Journal of Physical Chemistry |
Volume | 78 |
Issue number | 18 |
DOIs | |
State | Published - 1 Jan 1974 |
Externally published | Yes |
ASJC Scopus subject areas
- General Engineering
- Physical and Theoretical Chemistry