Vapor-liquid equilibria of binary and ternary mixtures containing ethyl lactate and effect of ethyl lactate as entrainer

• This work investigates ethyl lactate as an entrainer for extractive distillation.
• Methyl acetate + methanol was selected as a test binary azeotropic system.
• Isobaric VLE containing methyl acetate, methanol, and ethyl lactate were measured.
• Experimental VLE data were represented by Wilson and NRTL models.
• Solvent effects of ethyl lactate were evaluated by residue curve maps and separation factor.

This work investigated the effect of ethyl lactate as an entrainer for separation of a binary azeotropic system. Isobaric vapor–liquid equilibria (VLE) were determined for three binary systems, including methyl acetate + methanol, methyl acetate + ethyl lactate, and methanol + ethyl lactate using ebulliometry. Experimental VLE data were represented by the Wilson and NRTL models. The effect of ethyl lactate was evaluated by two approaches, including residue curve maps and calculation of S12 separation factors using binary Wilson parameters. Both the residue curve maps and the separation factors showed that ethyl lactate acted as an entrainer for extractive distillation of the binary azeotropic system methyl acetate + methanol. VLE for the ternary system methyl acetate + methanol + ethyl lactate were also measured, and the prediction of the behavior of this ternary system using the binary Wilson or NRTL parameters showed excellent agreement with the experimental VLE data.