Low transition temperature mixtures (LTTMs) as novel entrainers in extractive distillation

• Low transition temperature mixtures (LTTMs) have successfully been applied as entrainers for extractive distillation.
• Vapour–liquid equilibrium (VLE) data for pseudo-binary and ternary mixtures (ethanol–water–LTTM) were measured and fitted with the NRLT model.
• The ethanol–water azeotrope can be broken using malic acid–choline chloride 1:1 (MC 1:1), glycolic acid–choline chloride 1:1 and 3:1 (GC 1:1 and GC 3:1).
• The ethanol–water azeotrope can be moved to the pure ethanol side with lactic acid–choline chloride 2:1 (LC 2:1).

Low transition temperature mixtures (LTTMs) are evaluated as potential entrainers for extractive distillation for the first time. The selected LTTMs were lactic acid–choline chloride 2:1 (LC 2:1), malic acid–choline chloride 1:1 (MC 1:1), glycolic acid–choline chloride 3:1 (GC 3:1) and glycolic acid–choline chloride 1:1 (GC 1:1). Vapour–liquid equilibrium (VLE) data for the pseudo-binary mixtures of water–LTTM and ethanol–LTTM were measured and fitted with the NRLT model to calculate the interaction parameters. These parameters were used to predict the pseudo-ternary VLE data using the same model. The prediction was compared with new experimental data for the water–ethanol–LTTM system and the prediction was found to be adequate. It was found that the ethanol–water azeotrope can be broken by MC 1:1, GC 1:1 and GC 3:1 and it can be moved to the pure ethanol side with LC 2:1.

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