Purification of ethyl tert-butyl ether from its mixtures with ethanol by using an ionic liquid

In the last years, ionic liquids have emerged as a new class of compounds with negligible vapour pressure and excellent solvation properties, thus avoiding atmospheric contamination and flammable substances handling. Therefore, we can label ionic liquids as green solvents, constituting a very reliable alternative to traditional solvents. In this work, our aim was to investigate the possibility of using a well-known ionic liquid, 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim][OTf]), as solvent in extraction processes for the ethanol removal from its mixtures with ETBE. Hence, the experimental determination of the liquid–liquid equilibrium (LLE) for the ternary system ETBE + ethanol + [bmim][OTf] at 298.15 K was carried out. The correlation of LLE experimental data is commonly desirable as it allows the interpolation of tie-lines in the immiscible region of the system. The NRTL equation, a classical correlation model, was verified to accurately correlate the experimental data, even though it was not originally developed for systems containing electrolytes.