Phase behaviour and mathematical modelling for the system annatto seed oil in compressed carbon dioxide + ethanol as co-solvent

•Supercritical annatto seed oil is rich in tochotrienols and geranylgeraniol.•The system annatto seed oil + CO2 + ethanol exhibited complex phase behavior.•Artificial neural network model was is alternative for thermodynamic models.

This work reports phase equilibrium experimental data (cloud points) for the system annatto seed oil in compressed carbon dioxide + ethanol as co-solvent. The oil was obtained by supercritical fluid extraction at 40 °C and 20 MPa using carbon dioxide as solvent. The synthetic static method was employed for the measurements, which were carried out in a temperature range from 25 to 60 °C and up to 19.32 MPa. The experiments were carried out using (CO2 + ethanol) overall mass fraction compositions ranging from 0.82 to 0.99. Experimental results were modelled using artificial neural network (ANN). Results indicate a complex phase behavior for all temperatures investigated with the occurrence of vapor-liquid, liquid-liquid and vapor-liquid-liquid transitions. ANN modelling was an efficient alternative for the thermodynamic models to accurately analysis of the phase equilibrium at high pressure.

Graphical abstractDownload high-res image (159KB)Download full-size image