Surface speciation models of calcite and dolomite/aqueous solution interfaces and their spectroscopic evaluation
The composition and density of surface hydroxyl and carbonate groups on calcite and dolomite after contact at 25 C with solutions of different pH (3 to 12) and carbonate concentration (10{sup {minus}4} {le}{Sigma}CO{sub 2}{le} 0.1 M) were monitored by means of diffuse reflectance infrared (DRIFT) spectroscopy. Both for calcite and dolomite, broad high-intensity absorbance bands at about 3,400 and 1,600 cm{sup {minus}1} were observed at pH below 6 and carbonate concentration below 10{sub {minus}3} M. These bands are assigned to hydroxyl groups present at the mineral surfaces. At higher pH and {Sigma}CO{sub 2}, the intensity of these bands significantly decreases. On the contrary the intensity of the broad double band at about 1,400 cm{sup {minus}1} due to carbonate species (surface and bulk) for both minerals was found to increase significantly with increasing solution pH and carbonate concentration, being the lowest at pH {le} 5 and {Sigma}CO{sub 2} {le} 10{sup {minus}3} M. These observations correlate well with the surface speciation for calcite or dolomite/aqueous solution interface predicted based on surface complexation models (SCM).
- Research Organization:
- CNRS, Toulouse (FR)
- OSTI ID:
- 20050876
- Journal Information:
- Langmuir, Journal Name: Langmuir Journal Issue: 6 Vol. 16; ISSN LANGD5; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
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