SEMI-CONTINUOUS FRACTIONATION OF BIOACTIVE ESSENTIAL OILS WITH SUPERCRITICAL CARBON DIOXIDE. EXPERIMENTS, MODELING AND SEPARATION OF STEREOISOMERS.

GAÑAN, NICOLAS ALBERTO; VELEZ, ALEXIS RAFAEL; HEGEL, PABLO EZEQUIEL; BRIGNOLE, ESTEBAN ALBERTO

La Haya

Congreso; 13th European Meeting on Supercritical Fluids (ISASF 2011); 2011

International Society for the Advancement of Supercritical Fluids (ISASF)

In this work we study the fractionation of two bioactive essential oils (Salvia officinalis and Tagetes minuta) with carbon dioxide in a semi-continuous single stage apparatus. Essays were performed at 313 K and 80 atm in order to selectively remove the hydrocarbon monoterpenes and enrich the oxygenated and sesquiterpene fraction. Succesive extracts were collected during the process and their composition determined by GC-MS. From these results, the feasibility of a single stage deterpenation process with high purity and recovery of products is discussed. The systems carbon dioxide + essential oil are modeled and their behavior predicted using the group contribution equation of state (GC-EOS). With this thermodynamic model, the fractionation process is simulated using the mathematical background of batch distillation (Rayleigh equation). The correlation between the simulation and the experimental data is improved when a composition-dependent relative volatility is considered instead of only a pressure and temperature-dependent one. Separation of stereoisomers is also investigated. Although no selectivity is observed between optical isomers (alpha- and beta-thujone in Salvia oil), this is not the case for the stereoisomers Z- and E-ocimenone from Tagetes oil. These components exhibit an important degree of separation, which is an interesting feature considering that the bioactivity of stereoisomers is usually different.