Supercritical CO2 extraction of essential oils from Thymus vulgaris

Supercritical CO2 extraction of essential oil from Thymus vulgaris leaves w as studied using experimental data recently obtained in the Florys S.p.A. l aboratory. Mass transfer coefficients in the supercritical and solid phases from extraction curves at 40 degrees C and 20 MPa were evaluated using a m athematical model based on the local adsorption equilibrium of essential oi l on lipid in leaves. The adsorption equilibrium constant was fitted to the se experimental data, and internal and external mass transfer resistances w ere calculated, allowing identification of the mechanism controlling the ex traction process.