The kinetics of barite dissolution and precipitation in water and sodium chloride brines at 44–85 C
AG Christy, A Putnis - Geochimica et Cosmochimica Acta, 1993 - Elsevier
AG Christy, A Putnis
Geochimica et Cosmochimica Acta, 1993•ElsevierThe dissolution rate of natural barite cleavage fragments was measured in deionized water
and NaCl brines over the temperature range 44–85° C. Dissolution followed first-order
kinetics, with an activation energy of 24.9±10.1 kJ/mol. The observed insensitivity to stirring
rate and low absolute value of the rate constant (extrapolated k at 25° C= 3.30±1.31× 10− 3
L/m 2 s) indicated desorption rather than volume diffusion as the rate-determining step. The
NaCl concentration had no effect on k up to 0.1 M. Barite growth from supersaturated …
and NaCl brines over the temperature range 44–85° C. Dissolution followed first-order
kinetics, with an activation energy of 24.9±10.1 kJ/mol. The observed insensitivity to stirring
rate and low absolute value of the rate constant (extrapolated k at 25° C= 3.30±1.31× 10− 3
L/m 2 s) indicated desorption rather than volume diffusion as the rate-determining step. The
NaCl concentration had no effect on k up to 0.1 M. Barite growth from supersaturated …
Abstract
The dissolution rate of natural barite cleavage fragments was measured in deionized water and NaCl brines over the temperature range 44–85°C. Dissolution followed first-order kinetics, with an activation energy of 24.9 ± 10.1 kJ/mol. The observed insensitivity to stirring rate and low absolute value of the rate constant (extrapolated k at 25°C = 3.30 ± 1.31 × 10−3L/m2s) indicated desorption rather than volume diffusion as the rate-determining step. The NaCl concentration had no effect on k up to 0.1 M.
Barite growth from supersaturated aqueous solutions was also studied. Precipitation followed a second order rate law, k25°C = 162 ± 65 L2/sm2mol, Ea = 22.0 ± 14.3 kJ/mol, and was not sensitive to pH variation. A different rate law is likely to apply at high supersaturations, where a change in secondary growth morphology was observed.
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