Oxidation of Fe2+ ions in sulfate-and chloride-containing aqueous medium

Abstract

To study the effect of SO42- ions on the oxidation of Fe2+ tons in a sulfate- and chlortdc-containing aqueous medium, the final products formed by changing the ratio between SO42- and Cl- tons were investigated using Mossbauer spectroscopy and x-ray diffraction. The overall oxidation reaction of Fe-2* tons was composed of three distinct stages. The increase of [SO42-]/[Cl-] in the solution decreased the internal reaction rate, and the presence of SO42- tons caused the transformation of green rust I to green rust II. The increase of [SO42-]/[Cl-] enforccd the formation of goethite (alpha-FeOOH) as a final product, whereas it reduced the formation of lepidocrocite (gamma-FeOOH). The presence of akaganeite (beta-FeOOH), which formed in the chloride-containing aqueous medium, disappeared with the substitution of SO42- ions in the solution.