Formation of Goethite and Magnetite Rust via Reaction with Fe(II)

The effect of Fe(II) ion on the lepidocrocite-to-goethite transformation and magnetite formation in atmospheric corrosion have been investigated. Fe(II) was added into the initial corrosion products of a γ-FeOOH suspension at pH 7.0 and 30°C to simulate the further reaction. Results indicate that Fe(II) ions accelerated the dissolution of lepidocrocite. Both dissolution–reprecipitation and the oriented attachment mechanism play important roles in the lepidocrocite-to-goethite transformation. With an increase in the quantity of Fe (II) ions, magnetite was formed by the reaction of Fe (II) ions and lepidocrocite. Magnetite formation is classified as a topotactic transformation.