The Influence of Aluminum on the Formation of Iron Oxides. IV. The Influence of [Al], [OH], and Temperature

D. G. Lewis1 and U. Schwertmann
Institut für Bodenkunde, Technische Universität München Freising-Weihenstephan, B.R.D.
1 On study leave from the Department of Soil Science, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, South Australia 5064.

Abstract: Ferrihydrite was transformed to goethite and/or hematite at various temperatures, [OH], and [Al]. Increasing temperature and [Al] favored hematite, increasing [OH] favored goethite. A given [Al] induces hematite more effectively at lower [OH]. Al substitution in goethites increased linearly with log[Al], but was independent of temperature. At a given [Al], substitution increased with decreasing [OH]. In a plot of Al/Fe in the goethite against [Al]/[Fe(OH)4−] in solution a straight line was obtained for all preparations independent of [OH].

Key Words: Aluminum • Ferrihydrite • Goethite • Hematite • Iron oxides

Clays and Clay Minerals; June 1979 v. 27; no. 3; p. 195-200; DOI: 10.1346/CCMN.1979.0270304
© 1979, The Clay Minerals Society
Clay Minerals Society (www.clays.org)