Biochar from different feedstocks as catalysts for the conversion of algal lipid into biodiesel

Microalgae are a group of microorganisms capable to accumulate up to 80% triacylglycerol w/w, making them as one of the most promising renewable sources for biofuels. Biodiesel derived from algal oil is produced via transesterification process, where the oil is mixed with alcohol and a suitable catalyst at an elevated temperature. Recently, research has been focused on catalysts from renewable sources, like biomass and residues generated in households, in the form of biochar. Biochar is obtained from the incomplete combustion of carbon-rich biomass under oxygen-limited conditions. The aim of this work is to investigate the use of biochar as a heterogeneous catalyst for the conversion of algal lipid into biodiesel. Selected algal strains were cultivated and lipids were extracted. The effect of feedstock and pyrolysis temperature were investigated.  More specifically, biochar was produced from malt spent rootlets, coffee spent grains and olive kernels at pyrolysis temperatures ranging from 300 to 850^oC. The materials produced were fully characterized for their surface characteristics such as BET surface area, pore and micropore volume, thermogravimetric analysis and point of zero charge. The preliminary results showed that biochar from malt spent rootlets achieved about 50% conversion of lipids to fatty acid methyl esters during transesterification.