Direct saponification of wet microalgae by methanolic potassium hydroxide using acetone as co-solvent

Abstract

The fatty acids of microalgae are promising source of biodiesel and omega-3 fatty acids. The objective of this study is extraction of fatty acids from wet Dunaliela salina by direct saponification using methanolic potassium hydroxide and a suitable co-solvent. The study identified acetone as an efficient co-solvent for saponification of wet microalgal biomass by methanolic potassium hydroxide. The presence of acetone in methanolic KOH saponification produced 24% more fatty acid than its absence. Further optimization of concentration of acetone (80% v/v), concentration of potassium hydroxide (0.1% v/v) and solvent-dry biomass ratio (75:1) resulted in a maximum yield of 98% fatty acid. The proposed acetone assisted saponification of wet microalgal biomass could serve as an energy efficient route for fatty acid production since the reaction happens under room temperature and normal atmospheric pressure without any cell lysis or drying the biomass.