Excess molar enthalpies for mixtures of supercritical carbon dioxide and water + ethanol solutions

Excess molar enthalpies (HmE) for mixtures of supercritical CO2 and ethanol aqueous solutions were measured at 323.15 K and 7.64 and 15.00 MPa using an isothermal high-pressure flow calorimeter. HmE values obtained at the lower pressure are very exothermic while those obtained at the higher pressure are moderately endothermic. HmE for CO2 + H2O mixtures at 308.15 K and 7.64 MPa and 323.15 K and 15.00 MPa were also measured. These data are examined together with HmE data previously reported for mixtures of supercritical CO2 and ethanol aqueous solutions, vapor-liquid equilibrium data for the ternary system CO2 + H2O + ethanol and the excess enthalpy data for the three related binary systems. CO2-ethanol interactions are shown to be the main contribution to excess enthalpies when supercritical CO2 and ethanol aqueous solutions are mixed. Ternary excess enthalpies for CO2 + H2O + ethanol are also obtained. Kohler's method is used for estimating these ternary data from the excess enthalpy data of the three related binary systems.