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Effect of extensive drying on the cation exchange capacity of bentonites

Published online by Cambridge University Press:  09 July 2018

S. Kaufhold  and
R. Dohrmann
S. Kaufhold*
Affiliation:
BGR, Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, D-30655 Hannover, Germany
R. Dohrmann
Affiliation:
BGR, Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, D-30655 Hannover, Germany LBEG, Landesamt für Bergbau, Energie und Geologie, Stilleweg 2, D-30655 Hannover, Germany
*
*E-mail: [email protected]
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Abstract

Extensive drying of smectites can cause the interlayer space to break down (collapse). This can affect the properties of bentonites as geotechnical barriers of HLRW (highly radioactive waste) repositories. If and to what extent the collapse occurs depends strongly on the type of interlayer cation. In particular K is known to lead to ready dehydration, in contrast to Ca and Mg. In the present study, various bentonites and one illite/smectite clay were dried/heated at 90ºC for 1.5 a and in a different experiment at 120ºC for 4.5 a and investigated with respect to mineralogical and geochemical changes of the smectite.

Smectite alteration after extensive drying was restricted to changes of the exchangeable cations. The CEC decreased by 9% (90ºC test) and 14% (120ºC test). A slight decrease of exchangeable Na+ was observed following the 90ºC test. No significant further decrease was observed after the 120ºC test. In contrast, the larger cation exchange capacity (CEC) decrease after the 120ºC test could be explained by increased Ca/Mg fixation. A possible mechanism for the observations is presented.

Keywords

bentonitedryingheatingcation exchange capacitygeotechnical barriergeochemical barrierreactive chemical barrierHLRW repository
Type
Research Article
Information
Clay Minerals , Volume 45 , Issue 4 , December 2010 , pp. 441 - 448
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2010

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References

Cases, J.M., Bérend, I., Besson, G., Francois, M., Uriot, J.P., Thomas, F. & Poirier, J.E. (1992) Mechanism of adsorption and desorption of water vapour by homoionic montmorillonite. 1. The sodium exchanged form. Langmuir, 8, 2730–2739.Google Scholar
Cases, J.M., Bérend, I., Francois, M., Uriot, J.P., Michot, L.J. & Thomas, F. (1997) Mechanism of adsorption and desorption of water vapor by homoionic montmorillonite: 3. The Mg2+, Ca2+, Sr2+ and Ba2+ exchanged forms. Clays and Clay Minerals, 45, 8–22.Google Scholar
Churchman, G.J. & Tate, K.R. (1987) Stability of aggregates of different size grades in allophanic soils from volcanic ash in New Zealand. Journal of Soil Science, 38, 19–27.CrossRefGoogle Scholar
Dohrmann, R. & Kaufhold, S. (2009) Three new, quick CEC methods for determining the amounts of exchangeable calcium cations in calcareous clays. Clays and Clay Minerals, 57, 251–265.Google Scholar
Eberl, D.D., Środoń, J. & Northrop, H.R. (1986) Potassium fixation in smectite by wetting and drying. Pp. 296–326 in. Geochemical Processes at Mineral Surfaces (Davis, J.A. & Hayes, K.F., editors). ACS Symposium Series, 323, American Chemical Society.Google Scholar
Gradwell, M.W. & Birrell, K.S. (1954) Physical properties of certain volcanic clays. New Zealand Journal of Science and Technology, B 36, 108–122.Google Scholar
Greene-Kelly, K. (1953) Irreversible dehydration in montmorillonite, part II. Clay Minerals Bulletin, 2, 52–56.Google Scholar
Hofmann, U. & Klemen, R. (1950) Verlust der Austauschfahigkeit von Lithiumionen an Bentonit durch Erhitzung. Zeitschrift für Anorganische Chemie, 262, 95–99.Google Scholar
Horváth, I. & Novák, I. (1976) Potassium fixation and the charge of montmorillonite layers. Pp. 185–189 in: Proceedings of the International Clay Conference, Mexico City, 1975 (Bailey, S.W., editor). Applied Publishing, Wilmette, Illinois.Google Scholar
Kaufhold, S. & Dohrmann, R. (2008) Detachment of colloidal particles from bentonites in water. Applied Clay Science, 39, 50–59.Google Scholar
Kaufhold, S. & Dohrmann, R. (2009) Stability of bentonites in salt solutions I sodium chloride. Applied Clay Science, 45, 171–177.Google Scholar
Kaufhold, S. & Dohrmann, R. (2010) Stability of bentonites in salt solutions II potassium chloride — initial step of illitization? Applied Clay Science, published online: doi 10.1016/j.clay.2010.04.009.Google Scholar
Kaufhold, S., Dohrmann, R. & Jahn, R. (2007) Einfluss der Trocknung auf die Eigenschaften von Allophan. DBG Mitteilungen, 110, 647–648.Google Scholar
Kaufhold, S., Dohrmann, R., Koch, D. & Houben, G. (2008) The pH of aqueous bentonite suspensions. Clays and Clay Minerals, 56, 338–343.CrossRefGoogle Scholar
Kaufhold, S., Dohrmann, R. & Klinkenberg, M. (2010) Water-uptake capacity of bentonites. Clays and Clay Minerals, 58, 37–43.Google Scholar
Kitagawa, Y. (1971) The “unit particle” of allophane. American Mineralogist, 56, 465–475.Google Scholar
Meier, L.P. & Kahr, G. (1999) Determination of the cation exchange capacity (CEC) of clay minerals using the complexes of copper (II) ion with triethylenetetramine and tretraethylenepentamine. Clays and Clay Minerals, 47, 386–388.Google Scholar
Morodome, S. & Kawamura, K. (2009) Swelling behavior of Na- and Ca-montmorillonite up to 150°C by in situ X-ray diffraction experiments. Clays and Clay Minerals, 57, 150–160.Google Scholar
Ufer, K., Stanjek, H., Roth, G., Dohrmann, R., Kleeberg, R. & Kaufhold, S. (2008) Quantitative phase analysis of bentonites by the Rietveld method. Clays and Clay Minerals, 56, 272–282.Google Scholar