Alkylpyridinium Alkylsulfate Ionic Liquids as Solvents for the Deterpenation of Citrus Essential Oil

Abstract

The ionic liquids 1-methylpyridinium methylsulfate and 1-ethylpyridinium ethylsulfate were tested as solvents for the deterpenation by liquid-liquid extraction of citrus essential oil, simulated as a mixture of limonene and linalool. Liquid-liquid equilibrium data for the ternary systems limonene + linalool + 1-alkylpyridinium alkylsulfate (with the alkyl chain being methyl or ethyl) were determined at 298.15 K and atmospheric pressure, and suitably correlated with the UNIQUAC thermodynamic model. A comparison was established between the performance of these ionic liquids, as well as with others previously reported in the literature, to evaluate the influence of different structural features of the ionic liquids on their deterpenation ability.

Keywords:

• ionic liquid
• limonene
• linalool
• liquid-liquid equilibrium
• solvent extraction

ACKNOWLEDGEMENTS

The authors acknowledge the Spanish Ministry for Science and Innovation for financial support (project reference CTQ2009-10776). H.R. is also grateful to the same institution for support through the “Ramón y Cajal” program.