Murdoch University Research Repository

Welcome to the Murdoch University Research Repository

The Murdoch University Research Repository is an open access digital collection of research
created by Murdoch University staff, researchers and postgraduate students.

Learn more

Iron(II) oxidation by SO2/O2 in acidic media: Part II. Effect of copper

Zhang, W., Muir, D.M. and Singh, P. (2000) Iron(II) oxidation by SO2/O2 in acidic media: Part II. Effect of copper. Hydrometallurgy, 58 (2). pp. 117-125.

Link to Published Version:
*Subscription may be required


The oxidation of 0.1 and 0.5 M Fe2+ with O2 and with SO2/O2 mixtures is compared in the presence of CuSO4 at 80°C. The SO2/O2 system oxidises Fe2+ at a faster rate than the O2 system, particularly at low concentrations of Fe2+. With O2, the rate is second order with respect to Fe2+ concentration, and is catalysed by Cu2+. But with SO2/O2, the rate is independent of Fe2+ and is inhibited by Cu2+. It is proposed that copper catalyses the oxidation of Fe2+ by O2 through a mechanism that involves the formation of ionic CuO2+ and H2O2 as the oxidant. In contrast, oxidation by SO2/O2 is catalysed by Fe3+ in a free radical mechanism involving peroxysulphate radical that is inhibited by Cu2+. The presence of the free radical scavenger hydroquinone also inhibits the oxidation of Fe2+ with SO2/O2, but has little effect on the oxidation with O2. It is shown that when high concentrations of Fe2+ and Cu2+ are oxidised by SO2/O2, the reaction is initially dominated by the O2 reaction mechanism, but is overtaken by the SO2/O2 reaction mechanism as Fe2+ is oxidised and the concentration of Fe2+ decreases. The results indicate that the SO2/O2 system would oxidise ferrous ions faster than O2 to achieve higher levels of Fe(III) in solution during ferric leaching of minerals.

Item Type: Journal Article
Murdoch Affiliation(s): Parker Cooperative Research Centre for Integrated Hydrometallurgy Solutions
Publisher: Elsevier BV
Item Control Page Item Control Page