Experimental Study and Thermodynamic Modeling of the Lipid Extraction Process from Wet Microalgae

In this study, different ratios of methanol and hexane were used for lipid extraction from lyophilized microalgae and wet biomasses with 70 and 85 % moisture content. The amount of extracted crude lipid showed an increasing trend up to 1:1 volumetric ratio of methanol and hexane. Nevertheless, the increasing trend was diminished by further increase of methanol. A significant decrease of extracted crude lipids was observed with increase of moisture in low ratios of methanol. The highest amount of extracted fatty acids was achieved when same ratio of methanol and hexane were used, and amount of it was 2.30±0.53. The fatty acid recovery was decreased by increasing the moisture content. However, the profile of extracted fatty acids for different solvent mixture was nearly the same as dried microalgae. The best performance of extraction belongs to 1:1 hexane/methanol ratio which was 2.2±0.33 and 0.95±0.16 for 70 and 85% moisture content of biomass, respectively. The effect of temperature on the performance of extraction was also investigated, and the results showed that the recovery of both crude lipids and fatty acids was improved by increase of temperature, in which the crude lipid and fatty acid recovery was increased by about 17 and 36% at 65 oC comparing to the 25 oC. UNIQUAC thermodynamic model was employed to investigate the influences of moisture content and solvent ratio on lipid extraction process. Energy interaction parameters of the model were obtained by utilization of experimental data. Estimated results with AAD (%) inferior to 8.65 proved accuracy of it.