Hostname: page-component-cd9895bd7-gvvz8 Total loading time: 0 Render date: 2024-12-19T06:23:06.534Z Has data issue: false hasContentIssue false
  • English
  • Français

Acid Dissolution of Akaganiéite and Lepidocrocite: The Effect on Crystal Morphology

Published online by Cambridge University Press:  02 April 2024

R. M. Cornell  and
R. Giovanoli
R. M. Cornell
Affiliation:
ETH Zentrum Zürich, Laboratory of Inorganic Chemistry, CH-8092 Zürich, Switzerland
R. Giovanoli
Affiliation:
Laboratory for Electron Microscopy, University of Berne, Freiestrasse 3, CH-3000 Berne 9, Switzerland
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.

The rate of dissolution of akaganéite in HCl increased with time over the bulk of the reaction leading to a sigmoid dissolution vs. time curve. The bulk of the dissolution of lepidocrocite could be described by the cube root law. Transmission electron microscopy examination of partly dissolved crystals of akaganéite showed that acid attack proceeded mainly along the [001] direction. Initially, the tapered ends of the crystals became squared, and as dissolution continued the lengths of the crystals decreased steadily. At the same time, the crystals were gradually hollowed out. Acid attack was most pronounced at the edges of the crystals of lepidocrocite and appeared to involve a disruption of the hydrogen bonds that link the sheets of octahedra making up the structure. Defects also acted as sites for preferential acid attack. Dissolution of multi-domainic crystals involved preferential attack along the domain boundaries, as well as at the edges of the crystals. Single-domain crystals were well developed, but appeared to contain internal imperfections, which promoted the formation of holes on the otherwise unreactive (010) faces.

Keywords

AkaganéiteDissolutionIronLepidocrociteMorphologyTransmission electron microscopy
Type
Research Article
Information
Clays and Clay Minerals , Volume 36 , Issue 5 , October 1988 , pp. 385 - 390
Copyright
Copyright © 1988, The Clay Minerals Society

References

Brown, W. E. B. Dollimore, D., Galway, A. K., Bamford, C. H. and Tipper, C. F. H., 1980 Chapter 3 Comprehensive Chemical Kinetics Amsterdam Elsevier 41 – 109.Google Scholar
Cornell, R. M., Posner, A. M. and Quirk, J. P., 1974 Crystal morphology and the dissolution of goethite J. Inorg. Nucl. Chem. 36 1937 – 1946.CrossRefGoogle Scholar
Cornell, R. M., Posner, A. M. and Quirk, J. P., 1975 The complete dissolution of goethite J. Appl. Chem. Biotech. 25 701 – 706.CrossRefGoogle Scholar
Cornell, R. M., Posner, A. M. and Quirk, J. P., 1976 Kinetics and mechanisms of the acid dissolution of goethite (α-FeOOH) J. Inorg. Nucl. Chem. 38 563 – 567.CrossRefGoogle Scholar
Ellis, J., Giovanoli, R. and Stumm, W., 1976 Anion exchange properties of β-FeOOH Chimia 30 194 – 197.Google Scholar
Galbraith, S. T., Baird, T. and Fryer, J. R., 1979 Structural changes in β-FeOOH caused by radiation damage Acta Crystallogr. A35 197 – 200.CrossRefGoogle Scholar
Giovanoli, R. and Brütsch, R., 1974 Dehydration of γ-FeOOH: Direct observation of the mechanism Chimia 28 188 – 191.Google Scholar
Flixon, A. W. and Crowell, J. H., 1931 Dependence of reaction velocity upon surface agitation Ind. Eng. Chem. 23 923 – 981.Google Scholar
Lewis, D. G. and Farmer, V. C., 1986 Infrared adsorption of surface OH groups and lattice vibrations in lepidocrocite and boehmite Clay Miner. 21 93 – 100.CrossRefGoogle Scholar
Lim-Nunez, R., Gilkes, R. J., Schulze, L. G., van Olphen, H. and Mumpton, F. A., 1987 Acid dissolution of synthetic metal-containing goethites and hematites Proc. Int. Clay Conf. Denver, 1985 Indiana The Clay Minerals Society, Bloomington 197 – 204.Google Scholar
Schwertmann, U. and Taylor, R. M., 1972 The transformation of lepidocrocite to goethite Clays & Clay Minerals 20 151 – 158.CrossRefGoogle Scholar
Schwertmann, U. and Thalmann, H., 1976 The influence of [Fe(II)], [Si] and pH on the formation of lepidocrocite and ferrihydrite during oxidation of aqueous FeCl2 solutions day Miner. 11 189 – 200.Google Scholar
Schwertmann, U., 1984 The influence of aluminium on iron oxides: IX. Dissolution of Al-goethite in 6 M HCl Clay Miner. 19 9 – 19.CrossRefGoogle Scholar
Segal, M. G. and Sellars, R. M., 1982 Kinetics of metal oxide dissolution. Reductive dissolution of nickle ferrite by tris(picolinate)vanadium(II) J. Chem. Soc. Farad. Trans. I 78 1149 – 1164.CrossRefGoogle Scholar
Sidhu, P. S., Gilkes, R. J., Cornell, R. M., Posner, A. M. and Quirk, J. P., 1981 Dissolution of iron oxides and oxyhydroxides in hydrochloric and perchloric acids Clays & Clay Minerals 29 269 – 279.CrossRefGoogle Scholar
Watson, J. H. L. Cardell, R. R. and Heller, W., 1962 The internal structure of colloidal crystals of β-FeOOH and remarks on their assembly in Schiller layers J. Phys. Chem. 66 1757 – 1763.CrossRefGoogle Scholar