The adsorption mechanism of Sr2+ on the surface of goethite

CR Collins, DM Sherman, KV Ragnarsdottir*

*Corresponding author for this work

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

28 Citations (Scopus)

Abstract

Adsorption to iron(oxyhydr)oxide minerals such as goethite (alpha-FeOOH) may be an important retardation factor for the mobility of Sr-90 from radioactive waste repositories. EXAFS spectroscopy was used here to examine the coordination sphere around Sr2+ sorbed to goethite at pH 9.2 and 10.2. At both pHs studied, Sr was found to be coordinated to 8.0 +/- 10 atoms at a distance of 2.61 +/- 0.02. At pH 10.2, a further coordination sphere of 1.8 +/- 0.5 Fe atoms at 4.29 +/- 0.02 Angstrom demonstrated that Sr was adsorbed to goethite by an inner-sphere mechanism. From the EXAFS data, the crystallographic structure and morphology of goethite, it is proposed that the inner-sphere coordination of Sr is via two oxygen atoms (A-type hydroxyls) bound to adjacent Fe(III)) atoms on the dominant (110) surface of goethite. This is the first study of Sr sorption to an (oxyhydr)oxide mineral at an atomistic level.

Original languageEnglish
Pages (from-to)201-206
Number of pages6
JournalRadiochimica Acta
Volume81
Issue number4
Publication statusPublished - 1998

Keywords

  • strontium
  • goethite
  • EXAFS
  • adsorption
  • iron oxides
  • ALPHA-FEOOH
  • OXIDES
  • ENVIRONMENT
  • IONS

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