Liquid–Liquid Equilibria of Ternary Systems Containing Butyl Acetate, Pentyl Acetate, or Hexyl Acetate + 2-Hydroxyethylammonium Butanoate + Ethanol at 298.15 K

Abstract

This work studied the liquid–liquid equilibria (LLE) of three ternary systems containing acetates (butyl, pentyl, or hexyl acetate) plus ethanol plus the ionic liquid (IL) 2-hydroxyethylammonium butanoate (2-HEAB) at T = 298.15 K and p = 94.5 kPa. The IL was synthesized using a neutralization reaction. The Fourier-transform infrared spectroscopy (FT-IR) and the nuclear magnetic resonance (NMR) analyses were used to characterize the IL structure. For each ternary system, the equilibrium compositions were determined by a gravimetric method with empirical correlations based on the solubility curve, which was obtained by the cloud point method. The experimental results revealed that the acetate alkyl chain length decreases the system’s partial miscibility area. They also showed that ethanol is distributed preferably in the extract phase (IL-rich) with a partition coefficient (mole basis) of at least 2.5, which is an indicative that 2-HEAB can be used as a solvent for extracting ethanol from acetates, with reasonable values of selectivity (much higher than 1). The binary interaction parameters of the Non-Random Two-Liquid (NRTL) model were adjusted within the LLE experimental data and resulted in root-mean-square deviations up to 1.02%.