FRACTIONATION OF ALPHA-TERPINEOL AND LIMONENE USING SUPERCRITICAL CO2

Limonene and α-terpineol are terpenic compounds found in orange essential oils. Limonene has higher concentration and α-terpineol, although it is a minor component, has great potential for aroma and pharmacological applications. Fractionation technology with supercritical CO2 (SC-CO2) has the advantage of separating compounds without the need of co-solvents, as it changes the CO2 solvency power by modifying temperature and pressure. Few studies report the fractionation of α-terpineol in SC-CO2 as a mean to concentrate or purify this compound. The aim of this work was to investigate temperature and pressure conditions to separate α-terpineol from limonene, in order to concentrate the former. A mixture of orange essential oil and α-terpineol (60:40, m:m) was produced. We previously defined a process condition to solubilize the compounds of the mixture in SC-CO2 at 40 °C and 10.0 MPa, in order to evaluate the selectivity of CO2 to promote fractionation. Thus, we defined pressures (6.0, 7.0, and 8.0 MPa) and temperatures (40, 50 and 60 °C) to evaluate the fractionation process in SC-CO2. ANOVA (5%) and Tukey test were applied to compare possible significant differences between the evaluated conditions. At 40 °C and 10.0 MPa the solubility of the mixture was 0.062±0.006 g/g CO2. The fractionation process obtained two fractions: one precipitated in the separator (S1), where we expected to obtain concentrated α-terpineol; and an output fraction (S2), containing the compounds that remained solubilized in CO2. From the initial concentration of alpha-terpineol in the mixture (30.50%), the highest concentration of α-terpineol in S1 was obtained at 40 °C and 8.0 MPa (S1: 36.81±2.40% and S2: 21.94±1.28%) and the lowest concentration was obtained at 50°C and 6.0 MPa (S1:32.11±0.76% and S2: 13.93±0.62%). Therefore, it is possible to concentrate α-terpineol by modifying the process temperature and pressure, thus changing the thermodynamic properties of CO2.