Solubility of CO2 in aqueous solutions of KCl and in aqueous solutions of K2CO3

A high-pressure view-cell technique based on the synthetic method was used to determine the total pressure above aqueous solutions of two single salts (potassium chloride and potassium carbonate) and carbon dioxide. In the series of measurements with potassium chloride, the molality of the salt amounted to about (2 and 4) mol.(kg of water)(-1), the temperature ranged from about (313 to 433) K, and the molality of carbon dioxide ranged up to about 1 mol.(kg of water)(-1), corresponding to a maximum pressure of about 9.4 MPa. In the series of measurements with potassium carbonate, the stoichiometric molality of that salt amounted to about (0.43 and 1.7) mol.(kg of water)(-1) (stoichiometric mass fraction of the salt of about 0.056 and 0.19, respectively), the temperature ranged from about (313 to 393) K, and the ratio of the stoichiometric molalities of carbon dioxide to potassium carbonate ranged from about 0.7 to 3.6, corresponding to pressures from about (0.27 to 9.2) MPa. The vapor-liquid equilibrium of the systems (CO2 + KCl + H2O) and (CO2 + K2CO3 + H2O) (the latter allowing for the precipitation of KHCO3 that is important in connection with the "Hot Potassium Carbonate (Benfield) Process" and its modifications by activating additives) is described by means of a thermodynamic model based on Pitzer's molality scale based equation for the Gibbs excess energy of the aqueous phase. Model parameters are determined from the new carbon dioxide solubility data as well as from an extensive database adopted from the literature.