Liquid–liquid equilibrium calculations of systems containing vegetable oil + fatty acids + ethanol + water using new parameters for the unifac subgroups of ethanol and water

Abstract

Deacidification removes free fatty acids (FFA) from crude vegetable oils during the refining process. The removal of FFA carried out by liquid–liquid extraction has some advantages over chemical and physical refining processes: it saves energy and decreases neutral oil losses caused by undesirable chemical reactions. The knowledge of phase equilibrium behavior of systems involving vegetable oils, solvents, and FFA is necessary to design and optimize the liquid–liquid extraction processes for deacidification. In this context, the present work aims to predict the liquid–liquid equilibrium (LLE) for systems consisting of vegetable oil + fatty acids + ethanol + water, readjusting new UNIFAC interaction parameters just for the ethanol and water subgroups. Several experimental LLE data for multicomponent fatty systems available in the literature are used to adjust the new UNIFAC interaction parameters for the ethanol (EtOH) and water subgroups. The temperature range studied was 288.15 K to 323.15 K, at atmospheric pressure. The new 18 interaction parameters provide a considerably lower mean square error (0.87%) than the other works available in the literature. The results show that the developed procedures improve the capacity of the UNIFAC method to predict LLE for systems involved in the deacidification process of crude vegetable oil. The methodology employed in this work results in reduced computational calculations and a relatively small split with the complex dataset established by the UNIFAC-LL model.