X-ray standing wave investigation of the surface structure of selenite anions adsorbed on calcite

Likwan Cheng, Paul F. Lyman, Neil C. Sturchio, Michael J. Bedzyk*

*Corresponding author for this work

Research output: Contribution to journalArticle

37 Scopus citations

Abstract

The adsorption of selenite ions (SeO2-3) from a dilute aqueous solution onto a freshly-cleaved calcite (1014) surface was studied with the X-ray standing wave (XSW) technique. The complex ion SeO2-3 is found to selectively adsorb at the CO2-3 site via ionic exchange, forming a two-dimensional solid-solution of the form Ca(SeO3)x(CO3)1-x at the interface. The calcite (1014), (0006) and (1120) Bragg reflections were used to triangulate the Se position with respect to the calcite lattice. The local surface structure at the SeO2-3 adsorbate site, derived from the XSW results, is consistent with a model in which the base of the SeO2-3 trigonal pyramid aligns with (and replaces) the CO2-3 equilateral triangular group. The SeO2-3 adsorption saturated at a coverage of 0.02 monolayers. Under identical chemical conditions, selenate (SeO2-4) adsorption was inhibited.

Original languageEnglish (US)
Pages (from-to)L690-L695
JournalSurface Science
Volume382
Issue number1-3
DOIs
StatePublished - Jun 20 1997

Keywords

  • Adsorption
  • CaCO3
  • Calcite
  • Low-index single crystal surfaces
  • SeO
  • Selenite
  • Surface structure
  • X-ray standing waves (XSW)

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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