HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Loven, A. W. Articles by Thomas, H. C. Search for Related Content PubMed Articles by Loven, A. W. Articles by Thomas, H. C. GeoRef GeoRef Citation Agricola Articles by Loven, A. W. Articles by Thomas, H. C.

Adsorption Studies on Clay Minerals: IX. Ion-Exchange Properties of Natural and Thermally Altered Montmorillonite¹

ABSTRACT

The ion-exchange behavior of a thermally collapsed montmorillonite clay is compared with that of the natural mineral. Equilibrium measurements in the cesium-barium system at different temperatures demonstrate that the markedly increased selectivity for cesium, at low cesium content, shown by the altered clay is due to changes in the enthalpy of the exchange process partially compensated by a specific entropy effect favoring the sorption of barium. The standard free energy changes at 30C on the natural and altered mineral (for the sorption of 2 moles of cesium) are, respectively, –3.38 and –3.19 kcal. These do not reflect the considerable increase in selectivity for cesium of the heated clay at low cesium content.

Variation in the exchange capacity for barium of the heated clay when small amounts of cesium are present implies that this strongly sorbed ion renders many sites inaccessible to barium.

¹ Contribution from the Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina. This paper is based on the dissertation submitted by Andrew W. Loven to the faculty of the University of North Carolina in partial fulfillment of the requirements for the Degree of Doctor of Philosophy. The work was supported by the U.S. Atomic Energy Commission under Contract No. AT-(40-1)-2130.

² Former Graduate Student and Professor, respectively, Department of Chemistry, University of North Carolina, Chapel Hill.

Received for publication August 5, 1964. Accepted for publication January 22, 1965.