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Standard potentials (E o ) of iron(III) oxides under reducing conditions
Author(s) -
Fischer Walter R.
Publication year - 1987
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.19871500504
Subject(s) - hematite , goethite , lepidocrocite , ferrihydrite , chemistry , inorganic chemistry , iron oxide , magnetite , hydrogen , analytical chemistry (journal) , materials science , mineralogy , metallurgy , environmental chemistry , organic chemistry , adsorption
Partial reduction of iron(III) oxides with hydrogen in the presence of a platinum catalyst leads to an equilibrium state after 4–20 h. From the measured Eh, pH, and Fe 2+ concentration conditional standard potentials can be calculated using the formula E o (volt) = Eh + 0.059 lg(Fe 2+ ) + 0.18 pH which indicate the stability of Fe oxides against reduction. The reduceability decreases following the order ferrihydrite > lepidocrocite > hematite > goethite. The difference between hematite and goethite was more pronounced than that predicted from thermodynamic data.