Excess enthalpies of mixtures of olive oil and supercritical carbon dioxide

The excess enthalpies H-E of CO2 + olive oil mixtures were measured under t he conditions of temperature and pressure typically used in supercritical f luid extraction by means of an isothermal flow calorimeter. Values of H-E a t 35 degrees C and 17 MPa are moderately endothermic. Values of H-E at 35 d egrees C and 15 MPa are moderately endothermic in the olive oil-rich region and exothermic in the carbon dioxide-rich region. Values of H-E at 35 degr ees C and 9 MPa and at 80 degrees C and 9, 15 and 17 MPa are considerably e xothermic. The H-E versus composition plots show trends corresponding to a two-phase region. The changes observed in the excess enthalpy with temperat ure and pressure are discussed in terms of densities and critical constants of carbon dioxide, triolein and olive oil and liquid-vapor equilibrium dat a for CO2 + triolein, CO2 + oleic acid + triolein and CO2 + rapeseed oil. ( C) 1999 Elsevier Science B.V. All rights reserved.