Incorporation of Cr, Mn and Ni into goethite (alpha-FeOOH): mechanism from extended X-ray absorption fine structure spectroscopy

B Singh*, DM Sherman, RJ Gilkes, MA Wells, JFW Mosselmans

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

The crystal-chemical mechanisms by which transition metals are associated with goethite are fundamental to our understanding of the solubility and bioavailability of micronutrients and heavy metals in soils, and in the formation of laterite ore deposits. Transition metals such as Cr, Mn and Ni may sorb onto goetbite by forming surface precipitates, surface complexes or by replacing Fe(3+) in the goethite structure. In the work reported here, we investigated the local coordination environment of Cr, Mn and Ni in synthetic goethite using EXAFS spectroscopy. We demonstrate the isomorphous substitution for Fe(3+) by Cr(3+) (up to 8 mol.%), Mn(3+) (Up to 15 mol.%) and Ni(2+) (Up to 5 mol.%). We find, however, that the next-nearest-neighbour coordination environment changes with composition. The perturbations are likely to be responsible for limiting the accommodation of Cr(3+), Mn(3+) or Ni(2+) in the FeOOH structure.

Original languageEnglish
Pages (from-to)639-649
Number of pages11
JournalClay Minerals
Volume37
Issue number4
DOIs
Publication statusPublished - Dec 2002

Keywords

  • goethite
  • metal substitution
  • Mn
  • Cr
  • Ni
  • EXAFS
  • IRON-OXIDES
  • ALUMINOUS GOETHITES
  • NEUTRON DIFFRACTION
  • SYNTHETIC GOETHITE
  • FE
  • SUBSTITUTION
  • SOILS
  • EXTRACTION
  • CHEMISTRY
  • ELEMENTS

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