Abstract
Adsorption to iron(oxyhydr)oxide minerals such as goethite (α-FeOOH) may be an important retardation factor for the mobility of 90Sr 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 ± 1O atoms at a distance of 2.61 ± 0.02 Å. At pH 10.2, a further coordination sphere of 1.8 ± 0.5 Fe atoms at 4.29 ± 0.02 Å 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 language | English |
|---|---|
| Pages (from-to) | 201-206 |
| Number of pages | 6 |
| Journal | Radiochimica Acta |
| Volume | 81 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 1998 |
Bibliographical note
Funding Information: We are indebted to Igor Diakonov and Simon Randall for fruitful discussions and constructive comments on this manuscript. Thanks are due to Kim Goodman for assistance with ICP-AES analysis, John Dimery for surface area measurements, Roger 'S^ncent for TEM, Doug Robinson for XRD, and Fred Wheeler and Mike Dury for Workshop assistance. Andy Dent and Fred Mosselmans are thanked for their advice on EXAFS data collection and Atting. This study was funded by a NERC PhD studentship (for CRC) and EPSRC.Other keywords
- Adsorption
- EXAFS
- Goethite
- Iron oxides
- Strontium