Correlation of the solubility of solid hydrocarbons in supercritical CO2 using different equations of state and mixing rules

Abstract

Supercritical extraction process is a technique which has been increasingly applied in various industries in recent years. Solubility determination in supercritical region is the key feature for this process. However, high expenses and time consuming experiments for this task obligates the need for process modeling. In this study, a thermodynamic model has been proposed to correlate the solubility of solid hydrocarbons, namely, 1-hexadecanol, 1-octadecanol, anthracene, benzoin, fluorene, hexamethylbenze-ne, mandelic acid, naphtalene, palmitic acid, phenanthrene, propyl 4-hydroxy-benzoate, pyrene and stearic acid in supercritical conditions, using Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) equations of state with one-parameter van der Waals (vdW1) and two-parameters (vdW2) and covolume dependent (CVD) mixing rules. For the above combination of equations of state and mixing rules, binary interaction parameters have been determined, utilizing the differential evolution optimization strategy. The validity of the model has been assessed by comparing the experimental solubility data with the results obtained from thermodynamic model based on Average Absolute Relative Deviation percent (AARD %). An empirical correlation is proposed for the correlation of the solid solubilities in supercritical CO2. For each compound, the constants of this equation are obtained in such a manner to correlate the solubility at different temperatures and pressures.