Kinetics of Mn₂O₃ digestion in H₂SO₄ solutions

Title: Kinetics of Mn₂O₃ digestion in H₂SO₄ solutions
Creator: Walanda, Daud K.; Lawrance, Geoffrey Alan; Donne, Scott Wilfred
Relation: Journal of Solid State Chemistry Vol. 182, Issue 6, p. 1336-1342
Publisher Link: http://dx.doi.org/10.1016/j.jssc.2009.02.034
Publisher: Elsevier
Resource Type: journal article
Date: 2009
Description: The kinetics of Mn₂O₃ digestion in various H₂SO₄ solutions (0.5–2.0 M) and at various temperatures (ambient to 80 °C) to form solid γ-MnO₂ and soluble Mn(II) have been examined using X-ray diffraction. Using a modified first-order Avrami expression to describe digestion kinetics, rate constants in the range 0.02–0.98 h⁻¹ were found for Mn₂O₃ disappearance, and 0.03–0.42 h⁻¹ for γ-MnO₂ formation, with higher H₂SO₄ concentrations and temperatures leading to faster conversion rates. Also, for a particular set of experimental conditions, the rate of γ-MnO₂ formation was always slower than Mn₂O₃ disappearance. This was interpreted in terms of the solubility and stability of the soluble Mn(III) intermediated formed during the digestion. Activation energies for Mn₂O₃ dissolution and γ-MnO₂ formation were also determined.
Subject: manganese dioxide; hydrothermal synthesis; disproportionation; X-ray diffraction
Identifier: uon:8051
Identifier: http://hdl.handle.net/1959.13/916627
Identifier: ISSN:0022-4596
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