Rev. Bras. Ciênc. Solo.2002;26(1):117-24.

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Relationships between the isomorphic substitution of Fe for Al and the chemical and mineralogical characteristics of synthetic hematites

J. A. Sambatti, A. C. S. Costa, A. S. Muniz, E. Sengik, I. G. Souza Junior, J. M. Bigham

01/Mar/2002

DOI: 10.1590/S0100-06832002000100011

Hematites were synthesized with different degrees of isomorphic substitution (IS) of Fe for Al to a maximum of 16Almol%.The minerals were characterized by X-ray diffraction, total chemical analysis, extraction of iron and aluminum soluble in ammonium acid oxalate (Fe_o+Al_o), determination of the anion exchange capacity (AEC) and specific surface area (SSA).The results showed that the synthesis methods resulted in a minimum amount of impurities and that, in a general way, the foreseen values of isomorphic substitution were achieved.The SSA values were relatively low for the hematites with up to 10% of Al, and elevated for the hematites with 13 and 16% of Al of isomorphic substitution. A good correlation was observed between the SSA and the AEC with the amounts of Fe and Al, soluble in ammonium acid oxalate (Fe_o+Al_o).