Deterpenation of citrus essential oil via extractive distillation using imidazolium-based ionic liquids as entrainers

The deterpenation of citrus essential oils (CEO) is crucial in many industries to promote the stability and preserve the organoleptic properties of the final product, improving considerably the oxygenated fraction purity. Two imidazolium ionic liquids (ILs), [C4mim][OAc] and [C4mim]Cl, were applied as novel separation agents in a deterpenation process constituted by an extractive distillation column and a flash separator unit, aiming to remove hydrocarbon terpenes from the essential oil. The CEO was modeled as a mixture of the commonly found limonene (monoterpene) and linalool (monoterpenoid). To support the process simulation, isobaric vapor-liquid equilibrium measurements were conducted for the binary limonene/linalool and ternary limonene/linalool/IL mixtures at 5 kPa, and the data were successfully correlated with the NRTL model. The simulation results demonstrate that [C4mim]Cl improved the purity of linalool in the final product. Moreover, both [C4mim]Cl and [C4mim][OAc] reduced the required stages in the distillation column to obtain a terpeneless CEO with a certain purity, [C4mim]Cl being the most effective option.