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Surface Charge and Electrophoretic Properties of Colloids Obtained From Homoionic and Natural Bentonite

Published online by Cambridge University Press:  10 February 2011

T. Missana ,
M.J. Turrero  and
A. Adell
T. Missana
Affiliation:
CIEMAT -Departamento de Impacto Ambiental de la Energía Avenida Complutense 22, 28040 MADRID (SPAIN)
M.J. Turrero
Affiliation:
CIEMAT -Departamento de Impacto Ambiental de la Energía Avenida Complutense 22, 28040 MADRID (SPAIN)
A. Adell
Affiliation:
CIEMAT -Departamento de Impacto Ambiental de la Energía Avenida Complutense 22, 28040 MADRID (SPAIN)
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Abstract

Suspensions of colloids obtained from a Spanish bentonite were studied by potentiometric acid-base titrations and electrophoresis in order to analyse their surface chemical properties, which are responsible of their stability behaviour and that are very important to consider in radionuclides sorption modelling.

“Fast” titrations and “batch - back” titrations techniques were used to determine the contribution of the pH - dependent charge and the difference in the results obtained are discussed. Experimental data obtained by acid/base titrations were interpreted according the EDL theory. The model prediction agreed satisfactorily with the experimental data in the alkaline pH range. Protonation / deprotonation reactions of surface functional groups (SOH) appeared to be the main surface charge - determining mechanism in the alkaline pH range whereas ion - exchange type reactions, had to be taken into account over the acidic pH range. Surface potentials were calculated for different salt concentrations, from experimental data and taking into account both layer and edge sites charge contributions.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 608: Symposium QQ – Scientific Basis for Nuclear Waste Management XXIII , 1999 , 255
Copyright
Copyright © Materials Research Society 2000

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References

REFERENCES

[1] Missana, T., Turrero, M.J., Melon, A., Scientific Bases for Nuclear Waste Management XXII, MAT. RES. Soc. PROC., 556 - (1999) (In press).Google Scholar
[2] Holpen, H van, “An Introduction to clay colloids chemistry”, Wiley Interscience (1977)Google Scholar
[3] Stumm, W. and Morgan, J.J. in Aquatic Chemistry John Wiley and Sons, New York (1981)Google Scholar
[4] Sposito, G. in The surface chemistry of soils, Oxford University Press (1984)Google Scholar
[5]The FEBEX (Full scale Engineered Barrier EXperiment) consists in an “in-situ” test, in natural conditions and at a full scale; a “mock-up” test at almost full scale and a series of a laboratory test to complement the information from the two large scale tests. The aim of this project is to study the behaviour of components in the near field of a repository of high level wastes in crystalline rock.Google Scholar
[6] Dzombak, D., Morel, F. “Surface Complexation Modelling: Hydrous Ferric Oxides” N.Y. J. Wiley and Sons (1990)Google Scholar
[7] Bayens, B. and Bradbury, M.H., PSI Bericht Nr. 95 - 10, Paul Sherrer Institute (1995)Google Scholar
[8] Wanner, H, Albinsson, Y., Karland, O., Wieland, E., Wersin, P., Charlet, L., Radiochimica Acta, 66/67, 157–162 (1994)Google Scholar
[9] Shultess, C.P., Sparks, D.L., Soil, Sci, Soc. Am., 50, 1406–1411 (1986)Google Scholar
[10] ENRESA Technical Report “ Febex bentonite: Origin, properties and fabrication of blocks 05/98 (1998)Google Scholar
[11] Sondi, I., Biscan, J., Pravdic, V., J. Colloids Int. Sci., 178, 514 (1996)Google Scholar
[12] Lee, J. van der, “CHESS another speciation and surface complexation computer code” Technical Report N LHMIRD/93/39/CIG, Ecole de Mines de Paris (1993).Google Scholar
[13] Loeb, A. L., Wiersema, P.H., J Th G Overbeek The electrical double layer around a spherical colloid particle, MIT Press, Cambridge (1961)Google Scholar
[14] Hunter, R.J., “Zeta Potential in Colloid Science”, Academic Press London (1988)Google Scholar