Algal biodiesel production with engineered biochar as a heterogeneous solid acid catalyst

This study evaluates the use of engineered biochar as a heterogeneous solid acid catalyst for transesterification of algal oil derived from a native microalgal consortium. Biochar derived from sugarcane bagasse, coconut shell, corncob and peanut shell were evaluated for catalytic activity following surface modification. Peanut shell pyrolyzed at 400 °C with the sulfonic acid density of 0.837 mmol/g having 6.616 m²/g surface area was selected for efficient catalysis. The efficiency of transesterification was evaluated with 1-7 wt% catalyst loading, methanol: oil ratio of 6:1 to 30:1 at 55-85 °C over 2-8 h. Biodiesel yield of 94.91% was obtained with 5 wt% catalyst loading, MeOH: oil ratio of 20:1 at 65 °C after 4 h. Spectral analysis of algal biodiesel showed the presence of functional groups corresponding to esters. GC-MS analysis revealed the prominent presence of palmitic and oleic acids, further advocating the suitability of the technology for commercial application.