Effect of NaCl on gibbsite dissolution rate at pH 3 and 80[degree]C
- Yale Univ., New Haven, CT (United States). Dept. of Geology and Geophysics
The dissolution rate of synthetic gibbsite (Alcoa) was measured at pH 3 and 80 C as a function of solution saturation state and NaCl concentration. The experiments were conducted using well-stirred flow-through reaction vessels. Previous work in the laboratory has demonstrated a highly nonlinear dependence of the dissolution and precipitation rate of gibbsite, albite and kaolinite on solution saturation state (i.e., the Gibbs free energy of reaction - [Delta]G). Addition of NaCl to the input solution increases the ionic strength and therefore causes higher degrees of undersaturation due to the change in the activity coefficients. This effect was accounted for by calculating [Delta]G using activity coefficients based on the extended Debye-Huckel equation. Dissolution rates were measured using solutions with NaCl and without NaCl and the rates were then compared at the same [Delta]G. The effect of NaCl on the [Delta]G-functional dependence of the gibbsite dissolution rate can now be analyzed over the entire [Delta]G range of solution undersaturation, from near-equilibrium to far from equilibrium conditions. Preliminary results indicate that NaCl has different effects at different degrees of undersaturation. For example addition of NaCl to highly undersaturated solutions inhibits the rate of the overall dissolution reaction.
- OSTI ID:
- 5747019
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
152003* -- Geothermal Data & Theory-- Rock-Water-Gas Interactions
ALBITE
ALKALI METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM HYDROXIDES
ALUMINIUM SILICATES
CATALYTIC EFFECTS
CHLORIDES
CHLORINE COMPOUNDS
DISSOLUTION
ENERGY
EQUATIONS
EQUATIONS OF STATE
FELDSPARS
FREE ENTHALPY
GIBBSITE
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXIDES
KAOLINITE
MINERALS
OXIDE MINERALS
OXYGEN COMPOUNDS
PH VALUE
PHYSICAL PROPERTIES
PRECIPITATION
ROCK-FLUID INTERACTIONS
SEPARATION PROCESSES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SODIUM CHLORIDES
SODIUM COMPOUNDS
THERMODYNAMIC PROPERTIES