Deep Deterpenation of Citrus Essential Oils Intensified by In Situ Formation of a Deep Eutectic Solvent in Associative Extraction

Citrus essential oils (CEOs) are extensively utilized in the cosmetic, flavor, and chemical industries. The separation of the CEOs main compounds, terpenes and terpenoids, known as deterpenation, is required for practical applications. In this work, for deep deterpenation of the CEO, an intensified process of associative extraction was proposed for highly selective extraction of terpenoids into deep eutectic solvents (DESs) with organic salts. The formed DES was then recovered by a two-step reextraction using the antiextractants of organic solvent and water. The quaternary ammonium salt tetrabutylammonium chloride and the organic solvent n-hexane were determined based on the analysis of COSMO-RS interaction, and their extraction performance was experimentally validated. The terpeneless product (linalool with a high purity of 98.76%) was finally obtained from the model CEOs, which verifies the excellent performance for the proposed deep deterpenation process.