4. Conclusion
Direct transesterification of Chlorella spp. with an innovative mixed solvent composed of n-hexane and 75% ethanol showed a high FAEE yield. It was found that n-hexane as co-solvent presented a positive effect on FAEE yield, moving from 48.32% (without co-solvent) to 89.96%. And n-hexane is less toxic and cheaper than other solvents. The significant improvement of this technology is that the microalgae biomass was without pretreatment to disrupt the cell walls to enhance the conversion yield. It can be noted that the processes avoided the application of toxic chloroform with strong polarity and supercritical conditions.