The influence of Al on iron oxides. Part III. Preparation of Al goethites in M KOH

Abstract

AbstractAluminium substituted goethites (Fe, Al)OOH were synthesized from Fe(III), Al systems (ferrihydrites) in m KOH at room temperature. A linear correlation existed between degree of Al substitution and log[Al] in solution. Incorporation of up to 12 mole % Al was obtained. The rate of conversion of ferrihydrite to goethite decreased as [Al] increased. The goethite consisted of thin elongated plates approximately 0·1 µm long with serrated edges and reduced growth in the crystallographic X-direction. The presence of salts and the nature of the starting material either an Al-ferrihydrite or a ferrihydrite in aluminate solution did not influence the degree of substitution, but only the rate of formation of the goethite.