Lipid Extracted With Novel Solvents From Chlorella Spp.

Biodiesel has attracted increasingly attention of researchers as an alternative to fossil fuel and microalgae has many advantages in producing biodiesel. This study focused on lipid extraction with novel solvents from chlorella spp., which mainly contains 75% ethanol and N-Ethylbutylamine.(1) 75% ethanol with high permeability was applied in lipid extraction for the first time and its efficiency was investigated. Lipid content extracted with 75% ethanol is 1.4 and 4.0 times more than ethanol respectively for autotrophic and heterotrophy-Dilution-Photoinduction (HDP) chlorella spp.. With optimization of extraction process parameters (solvent amount and extraction time) and volume proportion of 75% ethanol/hexane, highest lipid yield of autotrophic and HDP chlorella spp. was 52.53 mg/g and 94.7 mg/g respectively, increasing by 23.4% and 56.3% compared to methanol, increasing by 47.5% and 99.4% compared to one step extraction.(2) Further comparative evaluation of 75% ethanol/n-hexane, Soxhlet, Sonication-B&D and B&D methods was carried out since we found that 75% ethanol/hexane method has a potential to measure total lipid content. By determining of crude lipid content, fatty acids content, fatty acid composition, polar/neutral lipid content and the content of high value-added products in the residual, it is revealed that the selection of most accurate method to measure total lipid in microalgae is affected by its different culture conditions. And the composition of extracted fatty acid is influenced by the water in solvent. Also, water in solvent carries away more protein, polysaccharide, but less chlorophyll. The crude lipid contents of autotrophic and HDP chlorella spp. were 25.7% and 29.8%, since lipid contents were 5.4% and 11.8% respectively.(3) N-Ethylbutylamine has the ability to extract lipid from HDP chlorella spp., and obtained 63% lipid yield under the optimized process conditions. And protein, chlorophyll amount in the algal residue were 84.2%?84.6%, higher than other methods. Lipid yield of 79.6% was achieved as to lipid extraction from broken wet algae with N-Ethylbutylamine, which could be a great advantage over n-hexane. Under the optimized condition of polarity switching process, lipid and solvent recovery efficiency were about 55% and 65% respectively. Energy consumption of solvent recovery accounted for only 8.61% of the total energy consumption. However, total cost is much higher than that of hexane and 75% ethanol/hexane due to the larger solvent cost. In general, N-Ethylbutylamine has the ability to extract lipid from chlorella spp., and can be directly recovered without distillation, which make it a promising lipid extracting agent.