Comparison study on transformation of iron oxyhydroxides: Based on theoretical and experimental data

We have investigated the catalytic transformation of ferrihydrite, feroxyhyte, and lepidocrocite in the presence of Fe(II). In this paper, the transformation from akaganeite and goethite to hematite in the presence of trace Fe(II) was studied in detail. The result indicates that trace Fe(II) can accelerate the transformation of akaganeite and goethite. Compared with the transformation of other iron oxyhydroxides (e.g., ferrihydrite, feroxyhyte, lepidocrocite, and akaganeite), a complete transformation from goethite to hematite was not observed in the presence of Fe(II). On the basis of our earlier and present experimental results, the transformation of various iron oxyhydroxides was compared based on their thermodynamic stability, crystalline structure, transformation mechanism, and transformation time.

The transformation of various iron oxyhydroxides in the presence of trace Fe(II) was compared based on experimental results, thermodynamic stability, crystalline structure, and transformation mechanism .Figure optionsDownload as PowerPoint slideHighlights
► Fe(II) can accelerate the transformation from akaganeite to hematite.
► Small particles of goethite can transform to hematite in the presence of Fe(II).
► Some hematite particles were found to be embedded within the crystal of goethite.
► The relationship between structure and transformation mechanism was revealed.