Hostname: page-component-586b7cd67f-2brh9 Total loading time: 0 Render date: 2024-11-26T16:06:12.943Z Has data issue: false hasContentIssue false
  • English
  • Français

The Nature of TiO2 in Kaolinite

Published online by Cambridge University Press:  01 July 2024

Charles E. Weaver
Charles E. Weaver*
Affiliation:
Georgia Institute of Technology, School of Geophysical Sciences, Atlanta, GA 30332, U.S.A.
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

SEM, TEM, and electron probe studies indicate that the anatase in Georgia kaolins, and probably anatase in general, consists of subspherical particles (TiO2 pellets) 0.05–0.1 µm dia. Some pure anatase aggregates may be pseudomorphic after ilmenite and have a tabular shape, but much of the anatase is formed from Ti that occurs as scattered ions in the octahedral sheets of biotite. When removed from the biotite this material forms TiO2 pellets. These pellets can occur as: single pellets; irregular aggregates; layered aggregates; spherical aggregates; mixed aggregates (with kaolinite); coated aggregates (with kaolinite). Physical energy can be used to break TiO2—kaolinite aggregates, separate single TiO2 pellets from kaolinite plates and remove kaolinite coatings from TiO2 aggregates.

Al and Si are present in all TiO2 aggregates and the Si—Al ratio is lower in the aggregates than in the kaolinite. An amorphous Si—Al compound may be present and act as a cement.

The anatase apparently is formed from Ti that is released from the parent mineral as Ti (OH)4. The Ti (OH)4 precipitates to form an amorphous hydrous oxide gel which dehydrates to form a granular aggregate of small anatase crystals.

Type
Research Article
Information
Clays and Clay Minerals , Volume 24 , Issue 5 , October 1976 , pp. 215 - 218
Copyright
Copyright © 1976 The Clay Minerals Society

References

DeKimpe, C., Gastuche, M. C. and Brindley, G. W. (1961) Ionic coordination in alumino-silicis gels in relation to clay mineral formation: Am. Min. 46, 1370–1381.Google Scholar
Dolcater, D. L., Syers, J. K. and Jackson, M. L. (1970) Titanium as free oxide and substituted forms in kaolinites and other clay minerals; Clays & Clay Minerals 18, 71–79.CrossRefGoogle Scholar
James, R. O. and Healy, T. W. (1972) Adsorption of hydrolyzable metal ions at the oxide water interface—III. A thermodynamic model of adsorption: J. Colloid Interface Sci. 40, 65–81.CrossRefGoogle Scholar
Jepson, W. B. and Rowse, J. B. (1975) The composition of kaolinite—an electron microscope microprobe study: Clays & Clay Minerals 23, 310–317.CrossRefGoogle Scholar
Sayin, M. and Jackson, M. L. (1976) Anatase and rutile determination in kaolinite deposits: Clays & Clay Minerals 24, 437–444.Google Scholar
Sherman, G. D. (1952) The titanium content of Hawaiian soils and its significance: Proc. Soil Sci. Am. 16, 15–18.CrossRefGoogle Scholar
Weaver, C. E. (1968) Electron microprobe study of kaolin: Clays & Clay Minerals 16, 187–189.CrossRefGoogle Scholar
Weaver, C. E. and Wampler, J. M. (1972) The illite–phosphate association: Geochimica et Cosmochemica Acta 36, 1–13.CrossRefGoogle Scholar
Weiser, H. B. and Milligan, W. O. (1939) The constitution of colloidal systems of the hydrous oxides: Chem. Rev. 25, 1–30.CrossRefGoogle Scholar