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Micropore formation in heated synthetic Al-goethites from a ferrous system

Published online by Cambridge University Press:  09 July 2018

H. D. Ruan  and
R. J. Gilkes
H. D. Ruan
Affiliation:
Soil Science and Plant Nutrition, Faculty of Agriculture, University of Western Australia, Nedlands 6907, Australia
R. J. Gilkes
Affiliation:
Soil Science and Plant Nutrition, Faculty of Agriculture, University of Western Australia, Nedlands 6907, Australia
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Abstract

Nitrogen adsorption and desorption isotherms were obtained for microcrystalline, platy crystals of synthetic Al-substituted goethites synthesized from the ferrous system and heated to 260°C. Specific surface area, cumulative pore area and frequency of mesopore wall-separations of 2–15 nm in size increased as Al substitution increased. Nanometre-size micropores developed at heating temperatures between 200 and 240°C and decreased during the growth of hematite crystals between 240 and 260°C. Aluminium substitution had little effect on micropore development and a moderate effect on mesopore development. The increases in micropore volume and specific surface area due to heating are much smaller than is reported in the literature for large, lath-like crystals of goethite that develop abundant slit-shaped micropores.

Type
Research Article
Information
Clay Minerals , Volume 31 , Issue 1 , March 1996 , pp. 75 - 79
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1996

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