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Dissolution of iron oxide in aqueous solutions of sulphur dioxide

University of British Columbia

A study has been made of the dissolution of naturally occurring α-iron oxide hydrate in acidified aqueous solutions of sulphur dioxide at 110°C. The dissolution was found to be independent of acidity at low concentrations of sulphur dioxide and inversely dependent on acidity at higher concentrations of sulphur dioxide. Both homogeneous and heterogeneous control of the reaction was observed. The addition of cupric ion to the system catalysed the rate. Dissolution is thought to occur via hydration of the oxide surface and subsequent reaction of undissociated sulphurous acid at the surface to form a ferric-sulphite complex. The rate determining step is considered to be the desorption of the complex from the surface. A limited study of the direct dissolution of iron oxide hydrate in sulphuric and perchloric acids at temperatures between 120 and 150°C is included. Under these conditions, the hydrated oxide surface is thought to undergo anion exchange during dissolution. Work carried out on the preparation and identification of the isomeric α- and γ-iron oxide hydrates is reported.

Text

2011-10-06

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http://hdl.handle.net/2429/37818

Metals and Materials Engineering

University of British Columbia

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