No abstract

Ionic liquids (ILs) are organic salts with low volatility and have different applications including organic synthesis, separation and extraction processes, fuel cell electrolyte, surfactants, among others. Protic ILs based on the N-methyl-2-hydroxyethyl ammonium cation and short chain carboxylic anions have simple synthesis and purification. However, as new substances few data are available for their thermodynamic properties and phase equilibria. In order to investigate the partition of these substances in alcohol-water, liquid-liquid equilibria data were determined experimentally for three ionic liquids (formed by the cation N-methyl-2-hydroxyethyl ammonium (m-2HEA) and the anions propionate (Pr), butanoate (B) and pentanoate (P)) with butanol and pentanol, at three different temperatures: 293.15K, 313.15K and 333.15K. The binodal curves are obtained by the turbidity method with gravimetric determination of all the components, curves are fitted using the Merchuk method. The tie-lines are also gravimetrically determined. The results confirm the high hydrophilicity of these ionic liquids, with partition coefficients of water-butanol and water-pentanol lower than 1. Data were correlated with UNIFAC.

Orange processing generates a high amount of waste rich in natural compounds that can be used to obtain added-value products or as raw material in biorefineries. Limonene (terpene) and linalool (oxygenated terpene) stand out among those bioproducts due to their organoleptic, antioxidant, and preservative properties. They are widely used in the food, cosmetic, and chemical industries, but their use as generally recognized as safe solvents is also gaining interest. In this work, separation of a mixture of limonene and linalool is proposed by extractive distillation with the ionic liquid 1-butyl-3-methylimidazolium acetate. To that aim, isobaric vapor–liquid equilibrium at 5 kPa was determined for the binary and ternary systems involved, and the data were successfully correlated with the NRTL and UNIQUAC models. The process was simulated, and the recovery of the ionic liquid was tested with a flash unit at very low pressure (0.1 kPa) or a stripping column (5 stages, 101.32 kPa) with air at the maximum operating temperature and a gas–liquid separator (101.32 kPa, 298.15 K). In the second case, an extractive column with an entrainer flow rate of 100 kg/h, number of stages N = 20, and reflux ratio R = 0.5 allows the separation of practically pure limonene and linalool.