The interest, in using supercritical fluids as a replacement for conventional liquid solvents have increased because of the need to reduce the use of organic solvents. Supercritical fluid extraction has been studied as an alternative method for conventional extraction methods with organic solvents and carbon dioxide has been the choice for the fluid in most of the applications. The use of supercritical carbon dioxide has many advantages compared to organic solvents. The advantages are, for example that CO2 is environmentally friendly and non-toxic solvent.
Modelling of supercritical fluid extraction processes is an important way to gain more valuable information of the extraction process. Using mathematical models, the extractions can be made more efficient and be better designed. In this thesis broken plus intact cells, and shrinking core models are being reviewed. Also combined broken and intact cells plus shrinking core model and some other kinetic models are reviewed.
In the experimental part, the aim was to find out the best pre-treatment method for the microalgae Scenedesmus, to determine the total lipid content, and to tentatively estimate the ability to use this microalgae for biodiesel production . The extraction method used was supercritical carbon dioxide extraction. The best lipid yield achieved was 11.5 % of dry weight. This yield was achieved by using grinding in mortar combined with methanol as a pre-treatment technique. In the extraction methanol and water were used with CO2 as co-solvents. Based on this research, the microalgae Scenedesmus is not suitable for biodiesel production.
