Fractionation of citrus essential oil by liquid-liquid extraction using a perforated rotating disc contactor

Citrus essential oils are important raw materials used in the formulation of many products, including soft and alcoholic drinks, flavoring agents, cosmetics, perfumes and toiletries. With the aim of improving the quality and, consequently, the price of the product, the separation of terpenic hydrocarbons and oxygenated compounds is required. The fractionation of essential oils may be achieved using diverse techniques, including liquid-liquid extraction using the appropriate solvents. This study was aimed at the fractionation of citrus essential oil model systems, composed of limonene and linalool mixtures, and crude orange essential oil (COEO) using continuous equipment known as a perforated rotating disc contactor (PRDC), in which mixtures of ethanol and water were used as the solvent. The effect of some variables, including disc rotation speed (DRS), linalool content in the feed (%LF), water content in the solvent (w4, S) and the ratio between the solvent and the feed mass flows (S/F), on process performance, using model mixtures, was studied. The fractionation process using the PRDC achieved concentration of linalool in the extract, on a solvent-free basis, 7-fold using a hydroalcoholic solvent with a water content of 30% by mass, and close to 10-fold using a solvent with 40% water by mass. With respect to the fractionation of COEO, the extraction indices reported here were in accordance with those determined for model systems, being obtained a concentration of oxygenated compounds of 10-fold using solvent with 30% of water and 15-fold using solvent with 40% of water.