The influence of pressure on the activity coefficients of the solutes and on the solubility of minerals in the system Na-Ca-Cl-SO sub 4 -H sub 2 O to 200 degree C and 1 kbar, and to high NaCl concentration

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90284-R· OSTI ID:6054036

Monnin, C ^[1]

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1. Centre National de la Recherche Scientifique, Toulouse (France)

A model is presented which is used to calculate the effect of pressure on activity coefficients of aqueous solutes in the system Na-Ca-Cl-SO{sub 4}-H{sub 2}O to 200{degree}C. Literature data for the density and compressibility of aqueous binary solutions of Na{sub 2}SO{sub 4} and CaCl{sub 2} to 200{degree}C are used to calculate the first and second pressure derivatives of Pitzer's ion interaction model parameters, as well as the standard molal compressibility and volume of these two salts. Empirical correlations between the apparent molal volume and compressibility of the aqueous electrolytes are used to guide the choice of the temperature dependent expressions used for the numerical representation of the derivatives of Pitzer's parameters with respect to pressure. The volumetric properties of multicomponent solutions in the Na-Ca-Cl-SO{sub 4}-H{sub 2}O system can be predicted from the information generated here and the volumetric equations of Rogers and Pitzer (1982) for NaCl. This model is then combined with the high temperature model of Moller (1988) of the same system in order to calculate activity coefficients at high pressures to 200{degree}C. The resulting model is validated by comparing calculated and measured solubilities of anhydrite and gypsum in pure water and in NaCl solutions up to 6 M.

• OSTI ID: 6054036
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 54:12; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ACTIVATION ENERGY
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ANHYDRITE
AQUEOUS SOLUTIONS
BRINES
CALCIUM CHLORIDES
CALCIUM COMPOUNDS
CALCIUM HALIDES
CALCIUM SULFATES
CHEMICAL REACTION KINETICS
CHLORIDES
CHLORINE COMPOUNDS
COMPRESSIBILITY
DISPERSIONS
DISSOLUTION
ENERGY
GYPSUM
HALIDES
HALOGEN COMPOUNDS
KINETICS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MINERALS
MIXTURES
MOLECULAR MODELS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PRESSURE EFFECTS
REACTION KINETICS
SODIUM CHLORIDES
SODIUM COMPOUNDS
SODIUM SULFATES
SOLUBILITY
SOLUTIONS
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
THERMODYNAMIC ACTIVITY
THERMODYNAMIC PROPERTIES