Separation of α‑Terpineol and Limonene from an Orange Essential Oil Mixture Using Supercritical CO2 Pressure Reduction.

Brazil is the world's largest orange producer, generating significant amounts of byproducts that are used to produce limonene-rich orange essential oil. In this sense, one possible alternative for its valorization is the biotransformation of limonene into α-terpineol, which has emerged as a promising valorization route, but the efficient separation of these compounds remains challenging due to their similar chemical nature. This work aimed to evaluate the solubility and fractionation behavior of α-terpineol and limonene in supercritical CO2 (SC-CO2) using a model mixture (orange essential oil + α-terpineol, 60:40 wt %), which simulated a biotransformation product. The best solubilization was found at 10 MPa and 40 °C. Supercritical fluid fractionation (SFF) was performed at different separator pressures (6-8 MPa) and temperatures (40-60 °C), to find optimal conditions for the selective recovery of α-terpineol. The SFF performed at 8 MPa and 40 °C achieved the precipitation of most α-terpineol. However, coprecipitation of limonene indicated limited selectivity under the tested conditions, likely due to molecular interactions in the complex multicomponent matrix. Calculated losses through the SFF at this same condition indicated a substantial limonene loss of nearly 50%, highlighting the challenges in designing an efficient system for terpene separation.