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.

中文翻译：

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甘油基深共溶剂对柑橘精油的分离

柑橘精油是主要由萜烯和萜类化合物组成的复杂烃混合物，被广泛用作食品，制药和精细化工行业的原料。然而，需要精油去悬浮（即，萜烯和萜类化合物的分离）以保持最终产品的质量以用于实际应用。当前，需要寻找有效和环境友好的溶剂来代替通常用作提取溶剂的有害挥发性有机化合物。因此，具有更好的环境友好特性的替代溶剂对于开发可持续的柑橘精油去污工艺至关重要。在这项工作中，由甘油（Gly）和氯化胆碱（ChCl）组成的可生物再生的深共熔溶剂（DES）被评估为可持续的溶剂，用于柑橘精油的去酯化，使用的是模型混合物和真正的柑橘粗橙精油（COEO）。在298.15 K和101.3 kPa下使用DES进行液-液萃取以脱除精油，并根据实验溶质分布系数和选择性值对溶剂性能进行了评估，并将其与使用类似导体的预测值进行了比较。实际溶剂的筛选模型（COSMO-RS）。还探讨了溶剂组成（即氢键受体/供体比）和添加水（纯DES与稀释DES）的影响。