Surface Speciation Models of Calcite and Dolomite/Aqueous Solution Interfaces and Their Spectroscopic Evaluation
| Autor: | and O. Barres, Oleg S. Pokrovsky, Jacques Schott, Jerzy A. Mielczarski |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Langmuir. 16:2677-2688 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la980905e |
| Popis: | 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 (10-4 ≤ ∑CO2 ≤ 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 3400 and 1600 cm-1 were observed at pH below 6 and carbonate concentration below 10-3 M. These bands are assigned to hydroxyl groups present at the mineral surfaces. At higher pH and ∑CO2, the intensity of these bands significantly decreases. On the contrary the intensity of the broad double band at about 1400 cm-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 ≤ 5 and ∑CO2 ≤ 10-3 M. These observations correlate well with the surface speciation for calcite or dolomite/aqueous solution interface predicted based on surface... |
| Databáze: | OpenAIRE |
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