Citrus essential oil terpenless by extraction using 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid: Effect of the temperature

Ionic liquids have awakened a big interest as solvents in the last years. In this work, the possibility of using an ionic liquid as solvent for the citrus essential oil deterpenation by liquid–liquid extraction has been studied. Citrus essential oil was simulated as the binary mixture (limonene + linalool) and equilibrium data for limonene + linalool + 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]) have experimentally been measured at 298.15 and 318.15 K. The experimental technique is based on direct analysis of phases at equilibrium using 1H NMR, which allows quantitative analysis of the three compounds. Linalool distribution ratios and selectivities have been calculated from experimental data. Slightly bigger values of these parameters were found at the lowest temperature. Correlation of the experimental LLE data was done by means of the non-random two-liquid (NRTL) equation. The nonrandomness parameter (α) was fixed to 0.1, 0.2, and 0.3, and the best results were obtained with α = 0.1. Correlation is performed for each temperature data set and also for both data sets simultaneously, getting in all the cases an adequate correlation.