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Résumé :
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The solubility of used frying oil in high pressure CO2 modified with four cosolvents (ethanol, methanol, acetone, and hexane) has been determined using a dynamic flow method. The aim of the work has been to analyze and compare the oil solubilities in CO2-cosolvent mixtures to those attained with pure CO2 in order to determine how the use of cosolvents affects the recovery of the undegraded triglyceride fraction of the waste oil. Another objective has been to obtain an empirical correlation to predict these solubility data for further scale-up applications. The pressure, temperature, and concentration ranges used to investigate the cosolvent effect were 30-35 MPa, 313-353 K, and 0.05-0.1 g of cosolvent/g of solvent, respectively. In such ranges the classical empirical models cannot be used since they do not account for the presence of a cosolvent. Therefore, a modification of the classical empirical correlations is proposed by introducing a cosolvent-concentration-dependent term. The modified model can be used to estimate the used oil solubilities in solvent—cosolvent mixtures and provides a better agreement with the experimental data, compared to the earlier models.
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