Aluminum speciation and equilibria in aqueous solution: II. The solubility of gibbsite in acidic sodium chloride solutions from 30 to 70C
- Oak Ridge National Lab., TN (United States)
The solubility of gibbsite in aqueous solutions was measured at ten ionic strengths made up of NaCl, HCl, and AlCl{sub 3} at 30, 50, and 70C with the initial acidity controlled by addition of HCl. The aluminum concentration was determined by ion chromatography, while the final equilibrium pH was measured at temperature. The equilibrium quotients for the reaction Al(OH){sub 3} + 3H{sup +} {r reversible} + Al{sup 3+} + 3H{sub 2}O were modeled using both an empirical equation including the Debye-Hueckel term and the Pitzer ion interaction treatment which incorporated the relevant single electrolyte and mixing interaction parameters currently available in the literature. In the latter treatment only four independent variables, including {theta}{sub AlNa}, {psi}{sub AlNaCl}, and two terms describing the equilibrium constant at infinite dilution, were needed to fit the data well within the projected experimental error. In general, these new equilibrium quotients differ markedly from results of all but the most recently published solubility studies. The thermodynamic parameters at infinite dilution are compared with those calculated from the individual components of the reaction available in the literature. These calculations lead to recommended thermodynamic values for the Gibbs energy of reaction at 25C of {minus}44.2 {plus minus} 0.3 kJ mol{sup {minus}1}, and a {Delta}G{sub f}{sup 0} (Al{sup 3+}, aq) of {minus}487.7 {plus minus} 1.5 kJ mol{sup {minus}1}, and a {Delta}H{sub f}{sup 0} (Al{sup 3+}, aq) of {minus}540.9 kJ mol{sup {minus} 1}. No evidence for aluminum chloride complexation was found by comparing solubility experiments in the presence of varying concentrations of sodium trifluoromethanesulfonate and sodium chloride at 50C and ca. 5 molal ionic strength.
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 7235603
- Journal Information:
- Geochimica et Cosmochimica Acta; (United States), Vol. 56:3; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
15 GEOTHERMAL ENERGY
ALUMINIUM CHLORIDES
SOLVENT PROPERTIES
GIBBSITE
SOLUBILITY
SODIUM CHLORIDES
AQUEOUS SOLUTIONS
ENTHALPY
EQUILIBRIUM
EXPERIMENTAL DATA
FREE ENTHALPY
HYDROCHLORIC ACID
ION EXCHANGE CHROMATOGRAPHY
MATHEMATICAL MODELS
PH VALUE
REACTION HEAT
TEMPERATURE RANGE 0273-0400 K
ALKALI METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM HYDROXIDES
CHLORIDES
CHLORINE COMPOUNDS
CHROMATOGRAPHY
DATA
DISPERSIONS
ENERGY
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXIDES
INFORMATION
INORGANIC ACIDS
MINERALS
MIXTURES
NUMERICAL DATA
OXIDE MINERALS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SEPARATION PROCESSES
SODIUM COMPOUNDS
SOLUTIONS
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES
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