Thermodynamic analysis of the reactions of iron oxides: Dissolution in oxalic acid
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Paspaliaris, I
(EN)
Panias, D
(EN)
Taxiarchou, M
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Douni, I
(EN)
Kontopoulos, A
(EN)
The mechanism of dissolution of pure iron oxides by means of organic acids comprises two different chemical pathways: (a) non-reductive dissolution and (b) reductive dissolution. In this paper, the thermodynamic analysis of these pathways for the iron oxides-oxalic acid system is presented. In low acid solutions (pH higher than 3) the only thermodynamically stable complex ions of bivalent and trivalent iron are [Fe2+(C2O4)(2)](2-) and [Fe3+(C2O4)(3)](3-). Uncomplexed Fe2+ ion can be identified only in high acid solutions, while uncomplexed Fe3+ ion is not likely to build-up in oxalic acid solutions. In the pH range 1-2 the [Fe3+(C2O4)(2)](-) and [Fe3+C2O4](+) ions are stable, while at pH less than 1, the [Fe3+HC2O4](2+) is the only ion existing. Copyright (C) 1996 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd.
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