Fe3+/Fe2+ redox equilibrium in the molten Na2O—B2B3 system by linear sweep voltammetry
1985; Elsevier BV; Volume: 30; Issue: 4 Linguagem: Inglês
10.1016/0013-4686(85)80032-3
ISSN1873-3859
AutoresAkira Sasahira, Toshio Yokokawa,
Tópico(s)Metal Extraction and Bioleaching
ResumoVoltammetry of Fe3+/Fe2+/Fe0 was carried out in Na2O—B2O3 melt. The redox equilibrium constant of Fe3+/Fe2+ and the diffusion coefficient of the Fe3+ ion were estimated from the voltammograms. The equilibrium constant increases with the increasing concentration of Na2O in the solvent. It was larger than that in Na2O—SiO2 and Na2O—P2O5 by 0.6—0.9 on a logarithmic scale at the same solvent basicity. The square root of the ratio of diffusion coefficients, (DFe3+/DFe2+)12, was between 1 and 2. As little of 0.001 to 0.004 mol. % Na2SO4 present as an impurity caused the appearance of several peaks in the voltammograms including a large anodic peak when the mol. % of the Fe2O3 was larger than 0.1. The existence of a complex of Fe2+ and S4+ was suggested, although its stability constant seemed quite small.
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