Experimental Determination of Dawsonite Stability and Reactivity: Implications for Geological CO2 Sequestration
- Laboratoire des Mecanismes et Transferts en Geologie, Toulouse, France
- ORNL
Over the last decade, a significant research effort has focused on determining the feasibility of sequestering large amounts of CO{sub 2} in deep, permeable geologic formations to reduce carbon dioxide emissions to the atmosphere. Most models indicate that injection of CO{sub 2} into deep sedimentary formations will lead to the formation of various carbonate minerals, including the common phases calcite (CaCO{sub 3}), dolomite (CaMg(CO{sub 3}){sub 2}), magnesite (MgCO{sub 3}), siderite (FeCO{sub 3}), as well as the far less common mineral, dawsonite (NaAlCO{sub 3}(OH){sub 2}). Nevertheless, the equilibrium and kinetics that control the precipitation of stable carbonate minerals are poorly understood and few experiments have been performed to validate computer codes that model CO{sub 2} sequestration. In order to reduce this uncertainty we measured the solubility of synthetic dawsonite according to the equilibrium: NaAlCO{sub 3}(OH){sub 2(cr)} + 2H{sub 2}O{sub 1} {r_equilibrium}Al(OH){sub 4}{sup -} + HCO{sub 3}{sup -} + Na{sup +} + H{sup +}, from under- and oversaturated solutions at 50-200 C in basic media at 1.0 mol {center_dot} kg{sup -1} NaCl. The solubility products (Q{sub s}) obtained were extrapolated to infinite dilution to obtain the solubility constants (K{sub s}{sup o}). Combining the fit of these logK{sub s}{sup o} values and fixing {Delta}C{sub pJ}{sup o} at -185.5J {center_dot} mol{sup -1} {center_dot} K{sup -1} at 25 C, which was derived from the calorimetric data of Ferrante et al. [Ferrante, M.J., Stuve, J.M., and Richardson, D.W., 1976. Thermodynamic data for synthetic dawsonite. U.S. Bureau of Mines Report Investigation, 8129, Washington, D.C., 13p.], the following thermodynamic parameters for the dissolution of dawsonite were calculated at 25 C: {Delta}G{sub r}{sup o} = 102.1 kJ {center_dot} mol{sup -1}, {Delta}H{sub r}{sup o} = 97.0 kJ {center_dot} mol{sup -1} and {Delta}s{sub r}{sup o} = -17.1 J {center_dot} mol{sup -1} {center_dot} K{sup -1}. Subsequently, we were able to derive values for the Gibbs energy of formation {Delta}{sub {line_integral}}G{sup 0}{sub 298.15} = -1782 {+-} 2 kJ {center_dot} mol{sup -1}), enthalpy of formation ({Delta}{sub {line_integral}}H{sup o}{sub 298.15} = -1960 {+-} 7 kJ {center_dot} mol{sup -1}) and entropy (S{sup o}{sub 298.15} = 121 {+-} 2 J {center_dot} mol{sup -1} {center_dot} K{sup -1}) of dawsonite. These results are within the combined experimental uncertainties of the values reported by Ferrante et al. (1976). Predominance diagrams are presented for the dawsonite/boehmite and dawsonite/bayerite equilibria at 100 C in the presence of a saline solution with and without silica-containing minerals.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1021929
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 71, Issue 18; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
CALCITE
CARBON DIOXIDE
CARBON SEQUESTRATION
CARBONATE MINERALS
DAWSONITE
DILUTION
DISSOLUTION
DOLOMITE
ENTROPY
EQUILIBRIUM
FORMATION HEAT
GEOLOGIC FORMATIONS
CARBON DIOXIDE INJECTION
KINETICS
PRECIPITATION
SIDERITE
SOLUBILITY
SYNTHESIS
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
TRAPPING
VALIDATION