The UNIFAC-LLE and COSMO-SAC ternary aqueous LLE calculations

Abstract The reliable description of a liquid-liquid equilibrium system is irrefragably important, given that liquid-liquid equilibrium has several important applications in industry, such as the extraction of propionic acid, reactant of esterification reaction for thermoplastics production, the removal of congeners of bioethanol through the equilibrium displacement by adding water, and the proper calculation of fuel blends equilibrium composition. The use of accurate models is one of the main necessities to achieve good predictions of a system. In this work, the use of the UNIFAC(LLE) and COSMO-SAC (2002) excess Gibbs energy models in liquid-liquid equilibrium is analyzed. Liquid-liquid equilibrium predictions of 55 ternary aqueous systems are performed, the models are compared and their accuracy evaluated. The systems may contain water, alkanes, alkenes, aromatic compounds, acids, alcohols and esters. The COSMO-SAC model yielded the most reliable results, although some systems were better described by the UNIFAC-LLE model.