Hostname: page-component-848d4c4894-pjpqr Total loading time: 0 Render date: 2024-06-20T05:14:12.169Z Has data issue: false hasContentIssue false
  • English
  • Français

Structural Fluorine in Sepiolite

Published online by Cambridge University Press:  02 April 2024

Julio Santaren ,
Jesus Sanz  and
Eduardo Ruiz-Hitzky
Julio Santaren
Affiliation:
Research and Development Department, Tolsa, S.A., P.O. Box 38017, 28080 Madrid, Spain
Jesus Sanz
Affiliation:
Instituto de Ciencia de Materiales, C.S.I.C., Serrano 115 bis, 28006 Madrid, Spain
Eduardo Ruiz-Hitzky
Affiliation:
Instituto de Ciencia de Materiales, C.S.I.C., Serrano 115 bis, 28006 Madrid, Spain
Get access Rights & Permissions [Opens in a new window]

Abstract

Sepiolite from Vallecas-Vicálvaro, Spain, contains 1.3% fluorine. Laser microprobe mass spectrometry of this sepiolite suggests the presence of fragments of (SiO2)nOMgF and (SiO2)nOMgOH, which are typical of the sepiolite structure. During thermal dehydroxylation, the fluorine in this sepiolite is removed simultaneously with OH groups at about 750°C. Nuclear magnetic resonance spectroscopy (NMR) of 19F indicates that the fluorine is located in the interior of the sepiolite structure, probably substituting for OH groups, and is homogeneously distributed. In the Vallecas-Vicálvaro sepiolite, about one of every four OH groups bound to Mg2+ is substituted by fluorine. The kinetics of extraction of Mg2+ and F- ions by acid treatment (1 N HCl) shows a more rapid extraction of Mg2+, with a monotonous decrease of the Mg/F ratio as the extent of extraction increases. These results support the internal location of the fluorine, as suggested by the NMR data.

Keywords

FluorineHydroxylLaser microprobe mass spectrometryDissolutionNuclear magnetic resonanceSepiolite
Type
Research Article
Information
Clays and Clay Minerals , Volume 38 , Issue 1 , February 1990 , pp. 63 - 68
Copyright
Copyright © 1990, The Clay Minerals Society

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

Alvarez, A., Pérez-Castells, R., Tortuero, F., Alzueta, C. and Günther, K. D., 1987 Structural fluorine in sepiolite; Leaching and biological effects J. Animal Physiol. & Anim. Nutr. 58 208 – 214.CrossRefGoogle Scholar
Brauner, K. and Preisinger, A., 1956 Struktur und Entstehung des Sepioliths Tschermarks Min. Petr. Mitt. 6 120 – 140.CrossRefGoogle Scholar
Daniel, M. E. and Hood, W. C., 1975 Alteration of shale adjacent to the Knight orebody, Rosiclare, Illinois Econ. Geol. 70 1062 – 1069.CrossRefGoogle Scholar
De Waele, J. K., Adams, F. C., Casal, B. and Ruiz-Hitzky, E., 1984 Laser microprobe mass analysis (LAMMA) of natural and organochlorosilane grafted sepiolite surfaces Mikrochim. Acta (Wien) 3 117 – 128.CrossRefGoogle Scholar
Denoyer, E., Van Grieken, R., Adams, F. C. and Natusch, D. F., 1982 Laser microprobe mass spectrometry. 1: Basic principles and performances characteristics Anal. Chem. 54 26A.CrossRefGoogle Scholar
Fijal, J., Zyla, M. and Tokarz, M., 1985 Chemical,sorptive and morphological properties of montmorillonite treated with ammonium bifluoride (NH4HF2) solutions Clay Miner. 20 81 – 92.CrossRefGoogle Scholar
Ingram, B. L., 1970 Determination of fluoride in silicate rocks without separation of aluminum using a specific ion electrode Anal. Chem. 42 1825 – 1827.CrossRefGoogle Scholar
Koritnig, S., 1963 Zur Geochemie des Fluors in Sedimenten Fortschr. Geol. Rheinl. Westfalen. 435 1 – 6.Google Scholar
Martin Vivaldi, J. L., Fenoll Hach-Ali, P. and Mackenzie, R. C., 1969 Palygorskites and sepiolites (hormites) Differential Thermal Analysis London Academic Press 553 – 573.Google Scholar
Newman, A. C. D. Brown, G. and Newman, A. C. D., 1987 The chemical constitution of clays Chemistry of Clays and Clay Minerals London Longman 1 – 128.Google Scholar
Pauling, L., 1960 The Nature of the Chemical Bond 3rd ed. New York Cornell University Press.Google Scholar
Sanz, J. and Stone, W. E. E., 1979 NMR study of micas, II. Distribution of Fe2+, F-, and OH- in the octahedral sheet of phlogopites Amer. Mineral. 64 119 – 126.Google Scholar
Thomas, J Jr. Glass, H. D., White, W. A. and Trandel, R. N., 1977 Fluoride content of clay minerals and argillaceous earth materials Clays & Clay Minerals 25 278 – 284.CrossRefGoogle Scholar
Van Vleck, J. H., 1948 The dipolar broadening of magnetic resonance lines in crystals Phys. Rew. 74 1168 – 1883.CrossRefGoogle Scholar