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Deterpenation of Citrus Essential Oils Using Glycerol-Based Deep Eutectic Solvents

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journal contribution
posted on 26.02.2018, 19:04 by Baranse Ozturk, Jesus Esteban, Maria Gonzalez-Miquel
Citrus essential oils are complex hydrocarbon mixtures mainly composed of terpenes and terpenoids and are widely used as raw materials in food, pharmaceutical, and fine chemical industries. However, essential oil deterpenation (i.e., separation of terpenes and terpenoids) is required to preserve the quality of the final product for practical applications. Currently, there is a need to find efficient and environmentally friendly solvents to replace the harmful volatile organic compounds that are conventionally used as extraction solvents. Therefore, alternative solvents with more benign and environmentally friendly characteristics are crucial to develop sustainable citrus essential oil deterpenation processes. In this work, biorenewable deep eutectic solvents (DES) composed of glycerol (Gly) and choline chloride (ChCl) are evaluated as sustainable solvents for citrus essential oil deterpenation, using model mixtures and real citrus crude orange essential oils (COEO). The liquid–liquid extraction process for essential oil deterpenation using DES was performed at 298.15 K and 101.3 kPa, and the solvent performance was evaluated in terms of the experimental solute distribution coefficients and selectivity values, which were compared against those predicted using the conductor-like screening model for real solvents (COSMO-RS). The effect of solvent composition (i.e., hydrogen bond acceptor/donor ratio) and the addition of water (pure DES vs diluted DES) were also explored. Overall results indicate the feasibility of using DES as extraction solvents for citrus essential oil deterpenation, with pure ChCl:Gly 1:2 providing the highest extraction yield, while the addition of water decreased the distribution coefficient but increased the selectivity of the process.