Dissolution of quartz into dilute alkaline solutions at 90/sup 0/C: a kinetic study
The rate of dissolution of Fontainebleau sand (pure quartz) into sodium hydroxide solutions (from 0.001 M to 0.5 M) has been determined at 90/sup 0/C in well-stirred vessels. Dissolution leads to an equilibrium state, controlled by the solubility of quartz in pure water as undissociated silicic acid H/sub 4/SiO/sub 4/. As long as the initial molality of sodium hydroxide does not exceed 0.02 mol x kg/sup -1/, the dissolution leads only to the formation of the three monomeric species H/sub 4/SiO/sub 4/, H/sub 3/SiO/sub 4//sup -/ and H/sub 2/SiO/sub 4//sup 2 -/, while polymers appear in the silica-rich solutions obtained in more alkaline media. The rate of dissolution can be represented by an adaptation of Stoeber's model to alkaline solutions; the basic assumption is that the quartz surface is partially covered by a layer of adsorbed silicate ions, which represent an intermediate species between solid and dissolved silica.
- Research Organization:
- Ecole Nationale Superieure des Mines de Paris (France)
- OSTI ID:
- 7222725
- Journal Information:
- Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 51:7; ISSN GCACA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580400* -- Geochemistry-- (-1989)
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMISTRY
DISSOLUTION
GEOCHEMISTRY
HYDROGEN COMPOUNDS
HYDROXIDES
KINETICS
MATHEMATICAL MODELS
MINERALS
MOLECULAR MODELS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
QUARTZ
REACTION KINETICS
SILICON COMPOUNDS
SILICON OXIDES
SODIUM COMPOUNDS
SODIUM HYDROXIDES
SOLVENT PROPERTIES