Liquid–Liquid Equilibrium Data for Refined Olive Pomace Oil + Oleic Acid + Ethanol + Water Systems: Application to Solvent Deacidification

ABSTRACT

This study presents the first experimental liquid–liquid equilibrium (LLE) data for quaternary systems composed of refined olive pomace oil, oleic acid, ethanol, and water at 303.15 K. These data are essential for the design and optimization of solvent‐based deacidification processes, particularly for oils with high free fatty acid (FFA) content and water in the solvent. Experiments were conducted with solvent mixtures containing 2.12–10.04 wt% water. The results showed that increasing water content slightly expands the two‐phase region and alters tie‐line orientation, indicating reduced distribution of FFA into the solvent‐rich phase. This behavior is associated with changes in solute–solvent interactions in aqueous ethanol mixtures, which reduce the apparent solubility of oleic acid in the solvent‐rich phase. Despite lowering the distribution coefficient, higher water content improved the selectivity between FFA and triacylglycerols (TAG), favoring selective extraction. Four different UNIFAC parameter sets were evaluated against the experimental data; the best agreement was achieved using the parameter set specifically developed for ethanol/water interactions in oil systems, with a mean deviation of 1.63% in phase composition and accurate predictions of both distribution coefficient and selectivity at 10.04 wt% water. These findings demonstrate the importance of accurate thermodynamic modeling for fatty systems and provide a reliable basis for the design of solvent‐based deacidification processes for high‐acidity vegetable oils.