Solubility behavior of quartz and corundum in supercritical water: A quantitative thermodynamic interpretation
Dissolution reaction equilibria for {alpha}-quartz (SiO{sub 2}) and corundum ({alpha}-Al{sub 2}0{sub 3}) in pure, supercritical water are quantified using a density-dependent thermodynamic model. The database of existing solubility literature for {alpha}-quartz (0.2-10 kb, 200--575{degrees}C) is shown to be consistent with the presence of two hydrolyzed SI(IV) ion forms: Si(OH){sub 4}(aq) and Si{sub 2}O(OH){sub 6}(aq); the corundum database (1-20 kb, 400--700{degrees}C) is consistent with Al(OH){sub 3}(aq) and Al(OH){sub 4}{sup {minus}}. A third Si(IV) ion hydroxocomplex, Si{sub 2}O{sub 2}(OH){sub 5}{sup {minus}}, is indicated at lower pressures (0.03-0.10 kb). The characteristic sigmoidal nature of the solubility isobars is explained by dimerization of Si(OH){sub 4}(aq) (at high densities) or the formation of anionic hydrolysis products, Si{sub 2}0{sub 2}(OH){sub 5}{sup {minus}} and Al(OH){sub 4}{sup {minus}}, in the low density region (p < 0.01 gm/cc). By means of the evaluated equilibria, thermochemical properties of Si{sub 2}O(OH){sub 6}(aq) and Si{sub 2}O{sub 2}(OH){sub 5}{sup {minus}} are made available for the first time.
- Research Organization:
- Knolls Atomic Power Lab. (KAPL), Niskayuna, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC12-76SN00052
- OSTI ID:
- 69332
- Report Number(s):
- KAPL-4790; ON: DE95012294; TRN: 95:015473
- Resource Relation:
- Other Information: PBD: May 1995
- Country of Publication:
- United States
- Language:
- English
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