Kinetics of Silica Condensation In Brines
Homogeneous nucleation and growth of silica from brines supersaturated in silicic acid has been studied over a range of pH (4.5-6.7), temperature (75-105 C), salinity, and silicic acid concentration (700 to 1200 ppm as SiO{sub 2}). The experimental technique involved analyses for molybdate-reactive silicic acid as a function of time after a supersaturated solution of H{sub 4}SiO{sub 4} was prepared by mixing aliquots of a stock silicate solution with buffered brine. The isothermal rate of SiO{sub 2} condensation is a strong function of supersaturation (C/C{sub eq}), pH, and salinity. The overall kinetics follow what is expected from the general theory of phase transitions and are adequately described by the Volmer-Becker-Doring expressions for condensation from solution. At supersaturations less than about 3, an induction or transition time is observed. It amounts to several hundred minutes at supersaturations of about 2.0
- Research Organization:
- EIC Corporation, Newton, MA
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 886858
- Report Number(s):
- COO-2607-4; CONF-760844-4
- Country of Publication:
- United States
- Language:
- English
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