2019 Volume 52 Issue 9 Pages 766-772
Eight organic solvents were examined for use during biocrude extraction from native microalgae cultivated at Minamisoma City, Fukushima prefecture, which is located in the cool temperature zone of Japan. Differences in biocrude yields attained by using the different organic solvents were found to correlate well with the Hildebrand solubility parameter. Biocrude yields comparable to those obtained with high-temperature extraction were attained during solvent extraction at ambient temperature for 24 h without cell disruption by sonication, which suggests that the solvent process could be easy to scale-up. Furthermore, upon fractionation with a silica gel column, chloroform : methanol (2 : 1, v/v), methanol : hexane (2 : 1, v/v), and methanol extracts exhibited similar lipid distribution profiles. The results indicated that differences in extraction yield were related to the cell wall penetration capabilities of the solvents. Hexane extract was found to be more selective for neutral lipids. Furthermore, the obtained biocrude products were characterized based on their thermogravimetric profiles. Biocrude extracted with methanol attained the highest yield (11.4%) and exhibited better thermogravimetric properties than the biocrude prepared with the other solvents. The results with native microalgae cultivated in the cool temperate zone of Japan not only exhibited reasonable yields (1.5–11.4%, dry ash-free basis), but also showed good thermogravimetric properties.