Liquid–liquid equilibria for ethyl esters + ethanol + water systems: Experimental measurements and CPA EoS modeling

The knowledge and the capacity to describe the liquid–liquid equilibria of systems composed of fatty acid ethyl esters, ethanol and water are crucial for an adequate design of the biodiesel washing units found in the ethylic biodiesel production processes. Since limited data is available for systems of this kind, in this work measurements were carried out for fatty acid ethyl esters + ethanol + water systems containing some of the fatty acid ethyl esters most commonly found in biodiesels: ethyl linoleate + ethanol + water at 313.15 K, technical grade ethyl oleate + ethanol + water at 298.15 K and ethyl palmitate + ethanol + water at 298.15, 308.15 and 333.15 K. The experimental data were predicted with the Cubic-Plus-Association equation of state (CPA EoS). Using temperature independent interaction parameters, obtained from binary data, this equation of state was able to provide a very good prediction of the phase diagrams of the studied systems, with average global deviations of only 3.09%.