A review on the extraction of lipid from microalgae for biodiesel production

•Mechanical and chemical methods of lipid extraction from microalgae are reviewed.•Efficient methods at optimized conditions minimize cost of lipid extraction.•Pretreatment of microalgae biomass along with solvent extraction is essential.•The extraction using chloroform–methanol solvent system showed the maximum lipid yield.

Biofuels produced from algal biomass are the most suitable alternative fuels for the future, as microalgae biomass can accumulate lipids within their cell similar to vegetable oils with a potential to produce 100 times more oil per acrel and than any other plants. The methods used for the extraction of lipid from microalgae are either mechanical or chemical method. The chemical methods of lipid extraction are Soxhlet extraction, supercritical fluid extraction, accelerated solvent extraction and mechanical methods are oil expeller, microwave assisted extraction, ultrasonic assisted extraction. This paper is a review of different methods used for extracting oils or lipids from microalgae biomass for biodiesel production. It is seen that lipid extraction yield from microalgae could be increased by using pretreatment methods such as ultrasonication and microwave-assisted techniques along with solvent extraction.