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

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Surf. Sci.

DOI:https://doi.org/10.1016/S0039-6028(97)00167-2· OSTI ID:943075

Cheng, L; Lyman, P F; Sturchio, N C; Bedzyk, M J

The adsorption of selenite ions (SeO{sup 2-}{sub 3}) from a dilute aqueous solution onto a freshly-cleaved calcite (10 {ovr 1} 4) surface was studied with the X-ray standing wave (XSW) technique. The complex ion SeO{sup 2-}{sub 3} is found to selectively adsorb at the CO{sup 2-}{sub 3} site via ionic exchange, forming a two-dimensional solid-solution of the form Ca(SeO{sub 3}){sub x}(CO{sub 3}){sub 1-x} at the interface. The calcite (10 {ovr 1} 4), (0006) and (11 {ovr 2} 0) Bragg reflections were used to triangulate the Se position with respect to the calcite lattice. The local surface structure at the SeO{sup 2-}{sub 3} adsorbate site, derived from the XSW results, is consistent with a model in which the base of the SeO{sup 2-}{sub 3} trigonal pyramid aligns with (and replaces) the CO{sup 2-}{sub 3} equilateral triangular group. The SeO{sup 2-}{sub 3} adsorption saturated at a coverage of 0.02 monolayers. Under identical chemical conditions, selenate (SeO{sup 2-}{sub 4}) adsorption was inhibited.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 943075
• Report Number(s): ANL/ER/JA-37302
• Journal Information: Surf. Sci., Journal Name: Surf. Sci. Journal Issue: 1997 Vol. 382; ISSN SUSCAS; ISSN 0039-6028
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CALCITE
CHEMISORPTION
ION EXCHANGE
MOLECULAR MODELS
MORPHOLOGY
SELENITES
SORPTIVE PROPERTIES