Membrane transport systems. III. A mechanistic study of cation-proton coupled countertransport

The rate of extraction and transport of potassium ions from a basic aqueous solution into a chloroform membrane containing a macrocyclic polyether (crown ether) - carboxylic acid has been investigated as a function of the following variables: stirring rate, potassium ion concentration, crown ether c...

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Bibliographic Details
Published in:Canadian journal of chemistry 1982-09, Vol.60 (17), p.2259-2267
Main Authors: Fyles, Thomas M, Malik-Diemer, Virginia A, McGavin, Cynthia A, Whitfield, Dennis M
Format: Article
Language:English
Subjects:
antiport
potassium
protons
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Summary:The rate of extraction and transport of potassium ions from a basic aqueous solution into a chloroform membrane containing a macrocyclic polyether (crown ether) - carboxylic acid has been investigated as a function of the following variables: stirring rate, potassium ion concentration, crown ether concentration, proton concentration, buffer concentration and composition, and crown ether-to-potassium ion ratio. Two rate regimes are found, a "zero order" regime where transport rate depends only on the carrier concentration and a "consecutive first order" regime where transport rate depends on the concentration of a crown ether - potassium complex. The kinetic data, together with partition coefficient and interfacial surface tension data, indicate that the rate determining steps in ion extraction occur at the interface. A mechanism involving rate limiting adsorption of carrier or desorption of complex, depending on the experimental conditions, is shown to be consistent with all available data.
ISSN:0008-4042
1480-3291
DOI:10.1139/v82-321