X-ray standing wave investigation of the surface structure of selenite anions adsorbed on calcite
نویسندگان
چکیده
The adsorption of selenite ions (SeO~-) 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 SeO zis found to selectively adsorb at the CO~ 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 SeO~adsorbate site, derived from the XSW results, is consistent with a model in which the base of the SeO~trigonal pyramid aligns with (and replaces) the CO3 zequilateral triangular group. The SeO~adsorption saturated at a coverage of 0.02 monolayers. Under identical chemical conditions, selenate ( S e O ] ) adsorption was inhibited. © 1997 Elsevier Science B.V.
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