The solubility of calcite, strontianite and witherite in NaCl solutions at 25°C

Abstract The solubility of CaCO 3 (calcite), SiCO 3 (strontianite), and BaCO 3 (witherite) has been determined in NaCl solutions from 0.1 to 6 m at 25°C. Activity coefficients estimated from Pitzer's equations with higher order interaction terms (θ and Ψ) were used to extrapolate the results to infinite dilution. Thermodynamic values of pK sp = 8.46 ± 0.03,9.13 ± 0.03 and 8.56 ± 0.04 were found, respectively, for CaCO 3 , SrCO 3 and BaCO 3 at 25°C. These results are in reasonable agreement with literature data. Since Pitzer parameters for the interactions of CO 3 2− with Ca 2+ , Sr 2+ and Ba 2+ were not used, our results indicate that they are not necessary at low values of P co2 .

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