Hostname: page-component-77c89778f8-vpsfw Total loading time: 0 Render date: 2024-07-17T05:42:40.717Z Has data issue: false hasContentIssue false
  • English
  • Français

Surface Charge Properties Of Kaolinite

Published online by Cambridge University Press:  10 February 2011

B.K. Schroth  and
G. Sposito
B.K. Schroth
Affiliation:
brians@ nature.berkeley.edu
G. Sposito
Affiliation:
Department of Environmental Science, Policy, and Management University of California, Berkeley, CA 94720-3110, USA
Get access

Abstract

The surface charge components of two Georgia kaolinites of differing degree of crystallinity (KGa-1 and KGa-2) were measured using procedures based on charge balance concepts. Permanent structural charge density (Σ0) was determined by measuring the surface excess of Cs, which is highly selective to permanent charge sites. The values of Σ0 determined were -6.3 ± 0.1 and -13.6 ± 0.5 mmol kg-1 for kaolinites KGa-l and KGa-2, respectively. The net proton surface charge density (σH) was determined as a function of pH by potentiometric titration in 0.01 mol dm-3 LiC1. Correction from apparent to absolute values of ΣH was made by accounting for Al release during dissolution, background ion adsorption, and charge balance. Lithium and Cl adsorption accounted for the remainder of the surface charge components. Changes in surface charge properties with time were measured after mixing times of 1, 3, and 15 hours (the latter representing “equilibrium”). Time-dependent behavior is believed to be caused by mineral dissolution followed by readsorption or precipitation of Al on the mineral surface. Both the point of zero net charge (p.z.n.c.) and the point of zero net proton charge (p.z.n.p.c.) changed with mixing time, generally increasing. The “equilibrium” p.z.n.c. values were approximately 3.6 and 3.3 for KGa-1 and KGa-2, respectively, while the corresponding p.z.n.p.c. values were about 5.0 and 5.4. The p.z.n.c. results were in good agreement with previous studies, but the values of p.z.n.p.c. were higher than other values reported for specimen kaolinite.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 432: Symposium S – Aqueous Chemistry and Geochemistry of Oxides , 1996 , 87
Copyright
Copyright © Materials Research Society 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Sposito, G., in Environmental Particles Buffle, J., Leeuven, H. van, Eds. (IUPAC Publications in Environmental and Analytical Chemistry, 1992), vol.1.Google Scholar
2. Chorover, J., Sposito, G., Measurement of Soil Surface Charge Components (University of California at Berkeley, Berkeley, CA, 1993), 48 pp.Google Scholar
3. Chorover, J. and Sposito, G., Geochim. Cosmochim. Acta 59, 875 (1995).Google Scholar
4. Charlet, L., Sposito, G., Soil Science Society of America Journal 51, 1155 (1987).Google Scholar
5. Anderson, S. J., Sposito, G., Soil Science Society of America Journal 56, 1437 (1992).Google Scholar
6. Lyklema, J., Chemistry and Industry 65, 741 (1987).Google Scholar
7. Lim, C. H., Jackson, M. L., Koons, R. D., Helmke, P. A., Clays and Clay Minerals 28, 223 (1980).Google Scholar
8. Wieland, E., Stumm, W., Geochimica et Cosmochimica Acta 56, 3339 (1992).Google Scholar
9. Braggs, B., Fornasiero, D., Ralston, J., Stsmart, R., Clays And Clay Minerals 42, 123 (1994).Google Scholar
10. Schindler, P. W., Liechti, P., Westall, J. C., Neth. J. Agri. Sci. 35, 219 (1987).Google Scholar
11. Charlet, L., Schindler, P.W., Spadini, L., Furrer, G.. and Zysset, M., Aquatic Sci. 55, 291 (1993).Google Scholar