Deterpenation of Citrus Essential Oil by Liquid−Liquid Extraction with 1-Alkyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)amide Ionic Liquids

Abstract

Three 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids, namely, those with ethyl-, hexyl-, or decyl- as the alkyl substituent chain, were evaluated as potential solvents for the deterpenation of citrus essential oil by liquid−liquid extraction. The citrus essential oil was simulated as a mixture of the terpene limonene and the oxyterpene linalool. The liquid−liquid equilibrium data for the ternary systems formed by limonene, linalool, and each of the ionic liquids selected were experimentally determined at 298.15 K. The suitability of the ionic liquids as solvents for the proposed process was evaluated by means of solute distribution ratio and selectivity values. The influence of the alkyl side chain in the imidazolium cation of the ionic liquids on the liquid−liquid equilibrium data was analyzed. By comparison with data previously reported in the literature for analogous systems, the influence of the ionic liquid anion on the proposed separation was also analyzed. The experimental data were satisfactorily correlated by means of both the nonrandom two-liquid (NRTL) and the universal quasichemical activity coefficient (UNIQUAC) thermodynamic models.

Improved concentration of citrus essential oil by solvent extraction with acetate ionic liquids

“…Still, their typical set of properties render them very interesting as neoteric solvents in reaction and separation processes, and specifically they can lead to the reconsideration of current solvent extraction processes, as well as envisioning of new ones [20]. For the particular case of deterpenation of essential oils, a series of ionic liquids were tested for the separation of compounds in a simplified, modelled citrus essential oil consisting of a mixture of limonene (a representative terpene) and linalool (a representative oxyterpene) [8,16,21,22]. Although different structural features in the constitutive ions were explored, seeking an optimisation of the ionic liquid to carry out the target separation, the results were only partially successful at best: some of the ionic liquids showed a high separation power of the terpene and the oxyterpene, but at the same time the low solubilities of the extracted oxyterpene would imply the need of prohibited amounts of solvent for the implementation of the extraction unit at an industrial scale.…”

Fractionation of lemon essential oil by solvent extraction: Phase equilibrium for model systems at T=298.2K

“…Furthermore, they can undergo hydrolysis reactions when exposed to heat and light, thus producing off -flavours that can be associated with the loss of the aromatic and flavour qualities of the oil [4].…”

“…Selecting a solvent is a critical step in the development of liquidliquid extraction processes because certain solvents improve the efficiency of the process [4]. Previous studies on optimising the process of deterpenation by liquid extraction have tested many different types of solvents, including ionic liquids [14][15][16]; glycols [17,18]; water [19,20]; aminoethanol [21]; acetonitrile, nitromethane and dimethylformamide [22]; and short chain alcohols, such as methanol [23,24], ethanol [6,19,[25][26][27][28], propanol, and butanol [29].…”

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

“…Importantly, the properties of the ionic liquid can be tailored to a substantial extent by judicious customization of its constitutive ions, enabling the possibility of optimizing the ionic liquid for a given application (6,7). Among other applications in liquid-liquid extraction, the use of ionic liquids for the deterpenation of essential oils has already been proposed (8)(9)(10). Several ionic liquids based on an imidazolium cation were investigated for the deterpenation of model citrus essential oil, allowing for an evaluation of the influence of the anion nature, as well as of the length of the cationic alkyl substituent on their deterpenation performance (10).…”

“…Among other applications in liquid-liquid extraction, the use of ionic liquids for the deterpenation of essential oils has already been proposed (8)(9)(10). Several ionic liquids based on an imidazolium cation were investigated for the deterpenation of model citrus essential oil, allowing for an evaluation of the influence of the anion nature, as well as of the length of the cationic alkyl substituent on their deterpenation performance (10). The best results were achieved for those ionic liquids with an alkylsulfonate or alkylsulfate anion, and with short alkyl substituents.…”