Inner-sphere adsorption geometry of Se(IV) at the hematite (100)-water interface

Jeffrey G. Catalano*, Zhan Zhang, Paul Fenter, Michael J. Bedzyk

*Corresponding author for this work

Research output: Contribution to journalArticle

61 Scopus citations

Abstract

The 3-dimensional structure of adsorption complexes on mineral surfaces provides insight into the fundamental mechanisms controlling sorption processes. This is important to the development of a general understanding of the behavior of contaminants such as selenite in the environment. The adsorption of selenite (SeO2-3) on the hematite (100) surface was studied using X-ray standing wave (XSW) measurements. Inner-sphere bidentate surface complexes bridging between adjacent singly-coordinated oxygen sites were identified as the primary adsorption site. The lack of binding to doubly-coordinated oxygen sites that were also exposed on the surface was likely due to differences in the reactivity or exchange kinetics of these sites or cation-cation repulsion, although the latter appears to be a secondary effect based on past observations. While these bridging bidentate geometries are similar to those inferred in past spectroscopic studies, the Se-Fe distances are such that these species might be misidentified as edge-sharing complexes if studied by EXAFS spectroscopy, highlighting the need for a fundamental understanding of mineral surface structure.

Original languageEnglish (US)
Pages (from-to)665-671
Number of pages7
JournalJournal of Colloid And Interface Science
Volume297
Issue number2
DOIs
StatePublished - May 15 2006

Keywords

  • Hematite
  • Inner-sphere adsorption
  • Selenite
  • XSW

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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