A simplified method to estimate the time evolution of oil extraction from different substrates by supercritical CO2.

To allow an easy individuation of the more suitable working conditions (temperature, pressure, flow rate, etc.) to be adopted to carry out the extraction of food grade oils from different substrates by supercritical CO2 (Sc-CO2), a simplified kinetic approach has been introduced. This kinetic model was utilised to describe supercritical fluid extraction (SFE) of oil by Sc-CO2 not only from seeds (sunflower, soybean and rape) but also from microalgae (Nannochloropsis sp., Schizochytrium sp. and Spirulina (Arthrospira) platensis) characterised by a lipid fraction with a high proportion of polyunsatured fatty acids (C20:5-3; C22:6-3; C18:3-6). Thanks to the high affinity occurring between oil and ScCO2 it was possible to introduce a simplified kinetic model able to describe the time evolution of oil extraction from substrates which deeply differ for biochemical and biophysical characteristics. Moreover the synergistic utilisation of the kinetic model introduced and of the Chrastil’s equation, allowed to predict the time evolution of oil extraction as a function of the: substrate used; amount of its fat content; mass of substrate charged inside the extractor; possible pretreatments carried out on the used substrate; flow rate of ScCO2; working conditions adopted (temperature, pressure and then ScCO2 density).