The effect of equipment design and process scale-up on supercritical CO2 extraction: Case study for Silybum marianum seeds

The present study was focused on improving the supercritical fluid extraction process dedicated to the recovery of highly valuable extract from Silybum marianum seeds. At first, the process was tested using supercritical CO2 at temperatures of 40 and 80 °C and pressures ranging from 100 to 300 bar. Obtained values were described using two literature models with acceptable agreement of experimental and calculated data. Further, the effect of the equipment design and process scale-up was investigated in four high-pressure units having volumes in the range from 280 mL to 40 L resulting in extraction yields up to 26 %. Based on the values of the parameters determined at the laboratory scale, the extraction process was successfully transferred to a semi-industrial scale. Finally, estimated costs for supercritical extract production in Poland for the year 2021 using a 1000 L high-pressure unit amounted to the price of 35.9 EUR per kg of extract