Excess molar enthalpies for mixtures of supercritical carbon dioxide and 1,8-cineole (original) (raw)
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The Journal of Chemical Thermodynamics, 2012
Mixtures of supercritical CO 2 and ethyl acetate (EA) are very often involved in supercritical fluid applications and their thermodynamic properties are required to understand and design these processes. Excess molar enthalpies (H E m ) for (CO 2 + EA) mixtures were measured using an isothermal high-pressure flow calorimeter under conditions of temperature and pressure typically used in supercritical processes: pressures from (9.00 to 18.00) MPa and temperatures from (313.15 to 333.15) K. Mixtures showed exothermic mixing; excess molar enthalpies exhibited a minimum in the CO 2 -rich region. The effects of pressure and temperature on the excess molar enthalpy of (CO 2 + EA) are large. The most exothermic H E m values were observed for a coincident CO 2 mole fraction value of 0.737 at T/K = (323.15 and 333.15) and P/MPa = 9.00: (À4489 and À4407) J Á mol À1 , respectively. Two-phase splitting was observed in the CO 2rich region at T/K = 333.15 and P/MPa = 9.00; in this region H E m varies linearly with CO 2 mole fraction. For a given mole fraction and temperature, mixtures become more exothermic as pressure decreases. These trends were analyzed in terms of molecular interactions, phase equilibria, density and critical parameters previously reported for (CO 2 + EA). Excess molar enthalpies here reported were correlated using the Soave-Redlich-Kwong and Peng-Robinson equations of state, and the classical mixing rule with two binary interaction parameters. The influence of the thermal effects on the phase behavior of (CO 2 + EA) mixtures formed in supercritical antisolvent precipitation experiments was discussed.
Excess molar enthalpies for mixtures of supercritical carbon dioxide and limonene
Fluid Phase Equilibria, 2006
Excess molar enthalpies (H E m ) for mixtures of supercritical CO 2 and ethanol aqueous solutions were measured at 323.15 K and 7.64 and 15.00 MPa using an isothermal high-pressure flow calorimeter. H E m values obtained at the lower pressure are very exothermic while those obtained at the higher pressure are moderately endothermic. H E m for CO 2 + H 2 O mixtures at 308.15 K and 7.64 MPa and 323.15 K and 15
Excess molar enthalpies for mixtures of supercritical CO 2 and linalool
Journal of Supercritical Fluids, 2008
Excess molar enthalpies (HmE) for mixtures of supercritical CO2 and linalool were measured at conditions of temperature and pressure typical of supercritical extraction processes: 313.15 and 323.15 K and 7.64, 10.00 and 12.00 MPa. The measurements were carried out using an isothermal high-pressure flow calorimeter. The effects of pressure and temperature on the excess molar enthalpy are large. Mixtures formed by low-density carbon dioxide and linalool show very exothermic mixing and excess molar enthalpies exhibit a minimum in the CO2-rich region. The lowest HmE values (≈−4000 J mol−1) are observed for mixtures at 313.15 K and 7.64 MPa. Mixtures formed by high-density carbon dioxide and linalool show considerably endothermic mixing (≈400–600 J mol−1) in the linalool-rich region and moderately exothermic mixing for the other compositions. On the other hand, HmE at 7.64 MPa and 313.15 and 323.15 K varies linearly with CO2 mole fraction in the two-phase region where a gaseous mixture and a liquid mixture of fixed composition, for a given condition of temperature and pressure, are in equilibrium. Results are analyzed in terms of phase equilibria, pure carbon dioxide density and CO2–terpene molecular interactions. Excess molar enthalpies are simultaneously correlated using the Soave–Redlich–Kwong and Peng–Robinson equations of state and the classical mixing rule. The significance of these large variations of HmE with temperature and pressure in the design of supercritical fluid deterpenation processes is discussed.
Excess molar enthalpies for mixtures of supercritical carbon dioxide and water+ethanol solutions
The Journal of Supercritical Fluids, 2005
Excess molar enthalpies (H E m ) for mixtures of supercritical CO 2 and ethanol aqueous solutions were measured at 323.15 K and 7.64 and 15.00 MPa using an isothermal high-pressure flow calorimeter. H E m values obtained at the lower pressure are very exothermic while those obtained at the higher pressure are moderately endothermic. H E m for CO 2 + H 2 O mixtures at 308.15 K and 7.64 MPa and 323.15 K and 15
Journal of Chemical and Engineering Data, 2010
Mixtures of supercritical CO 2 and acetone are very often involved in supercritical fluid applications, and their thermodynamic properties are required to understand and design these processes. Excess molar enthalpies (H m E ) for CO 2 + acetone mixtures were measured using an isothermal high-pressure flow calorimeter under conditions of temperature and pressure typically used in supercritical processes: pressures from (9.00 to 18.00) MPa and temperatures from (313.15 to 333.15) K. Mixtures showed exothermic mixing; excess molar enthalpies exhibited a minimum in the CO 2 -rich region. The effects of pressure and temperature on the excess molar enthalpy of CO 2 + acetone are large. The most exothermic H m E values were observed for a coincident CO 2 mole fraction value of 0.771 at (323.15 and 333.15) K and 9.00 MPa: (-4176 and -4366) J · mol -1 , respectively. Two-phase vapor-liquid CO 2 -rich regions are observed at (323.15 and 333.15) K and 9.00 MPa where H m E linearly varies with CO 2 mole fraction. For a given mole fraction and temperature, mixtures become more exothermic as pressure decreases. These trends were analyzed in terms of molecular interactions, phase equilibria, density, and critical parameters previously reported for CO 2 + acetone. Excess molar enthalpies here reported were correlated using the Peng-Robinson equation of state and the classical mixing rule with two binary interaction parameters. The influence of the thermal effects on the phase behavior of CO 2 + acetone mixtures formed in supercritical antisolvent precipitation experiments was discussed.
The Journal of Supercritical Fluids, 2010
Mixtures of supercritical CO 2 and N,N-dimethylformamide (DMF) are very often involved in supercritical fluid applications and their thermodynamic properties are required to understand and design these processes. Excess molar enthalpies (H E m ) for CO 2 + DMF mixtures were measured using an isothermal high-pressure flow calorimeter under conditions of temperature and pressure typically used in supercritical processes: 313.15 and 323.15 K at 9.00, 12.00, 15.00 and 18.00 MPa and 333.15 K at 9.00 and 15.00 MPa. The Peng-Robinson and the Soave-Redlich-Kwong equations of state were used in conjunction with the classical mixing rules to model the literature vapor-liquid equilibrium and critical data and the excess enthalpy data. In most cases, CO 2 + DMF mixtures showed very exothermic mixing and excess molar enthalpies exhibited a minimum in the CO 2 -rich region. The lowest H E m value (−4526 J mol −1 ) was observed for a CO 2 mole fraction value of 0.713 at 9.00 MPa and 333.15 K. On the other hand, H E m at 9.00 MPa and 323.15 and 333.15 K varies linearly with CO 2 mole fraction in the two-phase region where a gaseous and a liquid mixture of fixed composition are in equilibrium. The effects of pressure and temperature on the excess molar enthalpy are large. For a given mole fraction, mixtures become less exothermic as pressure increases or temperature decreases. These excess enthalpy data were analyzed in terms of molecular interactions, phase equilibria, density and critical parameters previously reported for CO 2 + DMF. All throughout this paper, the key concepts and modeling tools originate from the work of van der Waals: the paper is intended as a small piece of recognition of van der Waals overwhelming contributions to thermodynamics.
The Journal of Supercritical Fluids, 2007
An isothermal high-pressure flow calorimeter has been used to measure excess molar enthalpies (H E m ) for mixtures of supercritical CO 2 and N-methyl-2-pyrrolidone (NMP) under conditions of temperature and pressure typically used in supercritical CO 2 antisolvent precipitation (SAS): 313.15 and 338.15 K and 9.48, 15.00 and 20.00 MPa. Mixtures showed exothermic mixing; excess molar enthalpies exhibited a minimum in the CO 2 -rich region. The effects of pressure and temperature on the excess molar enthalpy of CO 2 + NMP are large. The lowest H E m values (≈−4500 J mol −1 ) were observed for mixtures at 338.15 K and 9.48 MPa. On the other hand, H E m at this condition of temperature and pressure varies linearly with CO 2 mole fraction in the two-phase region where a gaseous and a liquid mixture of fixed composition are in equilibrium. These data were analyzed in terms of phase equilibria data and critical locus for CO 2 + NMP and the related SAS experiments. Very exothermic excess molar enthalpies were obtained for conditions of temperature and pressure with marked coalescence phenomena for micro and submicro particles of tetracycline, amoxicillin and ampicillin produced by SAS. Excess molar enthalpies here reported and those previously measured at 298.15 K and 7.50, 10.60 and 12.60 MPa were correlated using the Soave-Redlich-Kwong and Peng-Robinson equations of state and the classical mixing rule with two binary interaction parameters.