Prediction of Mutual Solubilities of Heavy Components with Super‐Critical and Slightly Sub‐Critical Solvents: The Role of Equations of State and Some Applications of a Simple Expanded Lattice Model at Subcritical Temperatures

Abstract

Equations of State / High Pressure /Phase Equilibrium / Supercritical Extraction / ThermodynamicsThe use (and limitations) of equations of state for collating and predicting liquidlliquid and liquid/dense fluid equilibria is discussed with reference to 15 binary pairs (including some new data for the Carbon dioxide/Hexadecane system at 60°C) and three ternary combinations. It is concluded that the estimation of some of the parameters required for these calculations would be difficult if the solute was a complex substance Ber. Bunsenges. Phys. Chem. 88, 812-820 (1984) -0 Verlag Chemie GmbH, D-6940 Weinheim, 1984. OOO5-9021/84/0909-0812 $ 02.50/0 M. B. King et al.: Prediction of Mutual Solubilities of Heavy Components with Super-critical etc.813 about which little was known apart from its structural formula. -An alternative procedure is to apply activity coefficient expressions of the "regular solution" or UNIFAC type to each phase. Preliminary calculations along these lines are described and the physical basis for applying these methods under the relevant conditions is discussed. The "UNIFAC" approach in particular has been found to be encouraging, though the interaction parameters must be regarded as pressure dependent.

Mutual solubility study for 94.2:5.8 of ethanol to octane with supercritical carbon dioxide solvent

“…It seems the other interaction parameters effect which are function of pressure (such as a CO 2 =CH 3 and a CH 3 =CO 2 in this study) cover interaction parameters effect which are assumed as an average value (constant value) during calculations. This method was supported by King et al (1984) and .…”

“…(29) was then satisfied and the mole fractions (x E i ) and (x S i ) specified the required calculated phase compositions. The liquid-liquid equilibrium data for the system of carbon dioxide-hexadecane substances at various pressures and at temperature 25 8C were then used (Francis, 1954;King et al, 1984;Schneider et al, 1967), together with the regular solution derived model to determine the effective values for the a CO 2 =CH 3 or CH 2 or CH and a CH 3 =CO 2 interaction parameters as a function of pressure and independent of temperature as mentioned in the references King et al, 1984;Smith and Van Ness, 1987). Furthermore, by using the liquid-liquid equilibrium data for the system CO 2 -heptylalcohol at pressure of 65.8 bar and at temperature of 25 8C (Francis, 1954), together with the regular solution derived model, the effective values for the a CO 2 =OH and a OH=CO 2 interaction parameters as a function of pressure can be determined.…”

“…Theoretical data were calculated from regular solution equations and then compared with the experimental data. These equations are described in detail by King et al (1984). The estimation of the required parameters for these calculations would be difficult if the solute is a complex substance with little known information of the structural formula.…”

“…Furthermore, Fredenslund et al (1977) also generated the other interaction parameters. These parameters are independent of temperature and dependent on the pressure (Kassim and Davarnejad, 2006;King et al, 1984;Smith and Van Ness, 1987). The method of defining the parameters has been described in King et al (1984) and Kassim and Davarnejad (2006).…”

“…These parameters are independent of temperature and dependent on the pressure (Kassim and Davarnejad, 2006;King et al, 1984;Smith and Van Ness, 1987). The method of defining the parameters has been described in King et al (1984) and Kassim and Davarnejad (2006). The obtained data, activity coefficient, Gibbs function relationships and eventually mutual solubility data are calculated for the two phases in equilibrium by using regular solution equations.…”