Changes in chemical state and local structure of green rust by addition of copper sulphate ions

Abstract The X-ray absorption near edge structure (XANES), the extended X-ray absorption fine structure (EXAFS) and X-ray diffraction (XRD) measurements were used for characterising the effect of the addition of copper sulphate ions on the chemical state and local structure of hydrosulphate green rust (GR). Fe K edge XANES spectra showed that Fe(II) in GR was partially oxidised by the addition of the copper sulphate solution. Cu K edge XANES spectra showed that the copper sulphate ions in the GR suspension were reduced to zero charge copper. Radial structural functions indicated that the structure of GR comprised edge sharing of FeO 6 octahedral units, which was changed by the oxidation of Fe(II). In addition, it was found that the GR was partially oxidised to α-FeOOH by the addition of copper ions.