Experimental and computational investigation of two-component mixtures for the alkyl (ethyl, propyl and butyl) oleate in supercritical carbon dioxide

The main aim of the current study is to understand of solubility curve in solvents at supercritical conditions and including thermodynamics modeling, as well as van der Waals-type models. A thermodynamic approach was commissioned to predict the solubility of a model alkyl oleate monomers in supercritical carbon dioxide (Sc-CO₂). Furthermore, the experimental data of phase equilibrium were employed here which are based on measuring the solubility of alkyl oleate monomers in CO₂ at supercritical conditions, and the experiments were performed using common synthetic-type method. The thermodynamic equilibrium properties for the two-component mixture of ethyl oleate, propyl oleate and butyl oleate in Sc-CO₂ were reported. Bubble (dew)-point data determinations were performed through the synthetic method from various temperatures T= (313.2 to 393.2) K and pressures p = (3.07 to 31.71) MPa. The obtained results indicated that the phase equilibria of Sc-CO₂ were found to increase monotonically with the augmented of system temperatures and mole fraction of (ethyl oleate, propyl oleate and butyl oleate) in binary (solute + solvent) mixtures. The solubility curve of ethyl oleate, propyl oleate, and butyl oleate in the ethyl oleate + Sc-CO₂, propyl oleate + Sc-CO₂, and butyl oleate + Sc-CO₂ models rises as the temperature raises at a persistent pressure. The ethyl oleate + Sc-CO₂, propyl oleate + Sc-CO₂, and butyl oleate + Sc-CO₂ models show type-I phase behavior. Moreover, laboratory investigated results of these systems were adequately compared with the P-R EOS. RMSD for the ethyl oleate + Sc-CO₂ [κ_ij = 0.060, η_ij=-0.030], propyl oleate + Sc-CO₂ [κ_ij = 0.062, η_ij=-0.030], and butyl oleate + Sc-CO₂ [κ_ij = 0.061, η_ij=-0.030] models using 2 factors determined at 353.2 K were 4.06 %, 7.43 %, and 5.06 % correspondingly. Also, RMSD of ethyl oleate + Sc-CO₂, propyl oleate + Sc-CO₂, and butyl oleate + Sc-CO₂ systems predicted by adjusted factors at each temperature was 8.46 %, 9.43 %, and 6.29 %, respectively.