Ultrasound-Assisted Lipid Extraction from Chlorella sp.: Taguchi Design and Life Cycle Assessment

The present study delved into the enhancement of essential oil (EO) extraction process from Chlorella sp. through the implementation of ultrasound-assisted extraction. The Taguchi method was instrumental in determining the ideal parameters for the extraction process, which encompassed ultrasonic amplitude, reaction duration, hexane/ethanol (HE/EtOH) ratio, and processing temperature. The empirical findings indicated that optimal EO yield was realized at an ultrasonic amplitude of 80%, a reaction timeframe of 15 min, a HE/EtOH proportion of 3:1, and a temperature setting of 40 °C. These optimal conditions were further substantiated through additional experimentation, resulting in an EO yield of 18.8 ± 0.2%. A fatty acid profile analysis disclosed that the extracted EO predominantly consisted of long-chain fatty acids (C14-C20), with Palmitic, Heptadecanoic, Oleic, and Linoleic acids featuring as the main components. Nevertheless, a high unsaturation rate of 37.9% in the EO could potentially render it vulnerable to oxidative deterioration during storage, consequently affecting the quality of the ensuing biodiesel. A life cycle assessment of the sonication technique utilized for biodiesel production from Chlorella sp. highlighted that lipid extraction was the principal contributor to global warming and ecotoxicity, as per the CML and TRACI methods. Hence, the ultrasound-assisted extraction of EO from Chlorella sp. appears to be a promising and ecologically viable substitute to conventional techniques employed for biodiesel production.