Solubility and stability of zeolites in aqueous solution. 1: Analcime, Na-, and K-clinoptilolite
- Pennsylvania State Univ., University Park, PA (United States). Ore Deposits Research Section
The solubilities of analcime and clinoptilolite were determined in dilute, weakly alkaline, aqueous solutions below 300 C and at vapor-saturated pressures. Analcimes used in this study were from Mont St. Hilaire, Quebec (an{sub 1}, Si/Al = 2.02) and Wikieup, Arizona (an{sub 2}, Si/Al = 2.55); clinoptilolite samples were from Castle Creek, Idaho (Si/Al = 4.50). The effects of alkali content (Na,K) on clinoptilolite solubility were determined by using cation-exchanged varieties of the Castle Creek material. The logarithm of the equilibrium constants of the solubility-controlling reactions were fit to the function: log K = A + BT + C/T + D log T. At 25 C, log K values for the Mont St. Hilaire analcime, Wikieup analcime, Na-clinoptilolite, and K-clinoptilolite are {minus}16.1, -15.0, -26.5, and {minus}28.1, respectively. These data were combined with the thermodynamic properties of the aqueous species Si(OH){sub 4}, Al(OH){sub 4}{sup {minus}}, Na{sup +}, K{sup +}, and liquid water to determine standard Gibbs free energies of formation as a function of temperature. Values of {Delta}G{sub f}{sup 0} at 25 C and 1 bar for the Mont St. Hilaire analcime and Wikieup analcime are {minus}3,089.2 and {minus}3,044.4 kJ/mol, respectively. The {Delta}G{sub f}{sup 0} values for hydrous Na-clinoptilolite and K-clinoptilolite, respectively, are {minus}6,267.9 and {minus}6,107.4 kJ/mol at 25 C and 1 bar. The solubility data reported here, and results obtained from previous calorimetric studies, indicate that the aluminosilicate frameworks of analcime and clinoptilolite are stabilized by an increase in Al content.
- Sponsoring Organization:
- USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- FG02-96ER14634
- OSTI ID:
- 653507
- Journal Information:
- American Mineralogist, Vol. 83, Issue 7-8; Other Information: PBD: Jul-Aug 1998
- Country of Publication:
- United States
- Language:
- English
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