A comparative study of the kinetics of the oxidation of iron(II) by oxygen in acidic media - mechanistic and practical implications

Nicol, M.J.ORCID: 0000-0002-8757-161X (2020) A comparative study of the kinetics of the oxidation of iron(II) by oxygen in acidic media - mechanistic and practical implications. Hydrometallurgy, 192 . Art. 105246.

Abstract

The results of this comparative study have shown that in 1 M acid solutions, the differences in reactivity of iron(II) for reduction of oxygen are within about an order of magnitude of each other for the systems studied at 40 °C. This applies to both the uncatalysed and copper(II) catalysed systems. The exception is the chloride system in which the rate can be significantly increased by increasing the chloride concentration. The other main conclusion is that although catalysis by copper(II) ions can be significant there exist conditions (iron(II) and (III) concentrations) for which the effect is not that important.

Rate equations for both the uncatalysed and catalysed reactions have been derived that apply equally to all the systems studied. Values for the various rate constants have been obtained by analysis of extensive kinetic data in 1 M acid solutions at 40 °C. A limited electrochemical study has been used to derive values for the equilibrium constant for the reaction involving the iron(III)/iron(II) and copper(II)/copper(I) couples. An attempt has been made to compare relevant constants with previously published data and to derive a mechanism that is consistent with the kinetic results.

This study has shown that the use of methanesulfonic acid as an oxidative leaching medium does not offer any advantages and is the least reactive of the systems studied.

Item Type:	Journal Article
Murdoch Affiliation(s):	College of Science, Health, Engineering and Education
Publisher:	Elsevier BV
Copyright:	© 2020 Elsevier B.V.
URI:	http://researchrepository.murdoch.edu.au/id/eprint/54599

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