Kinetics-based activation energy of one-step optimized transesterification in producing quality biodiesel from black soldier fly larvae oil

Abstract

Black soldier fly (BSF; Hermetia illucens), is an appealing solution towards organic waste reduction, and biodiesel production owing to its high oil content at maturity. However, with more commercial focus on the insect protein, its oil fraction has been an underutilized by-product from the larval processing industry. In this regard, the current study has successfully unveiled the one-step alkaline-catalyzed transesterification, which achieve the highest biodiesel yield of 88.08 % ± 0.75 %, at optimum parameters of 6:1 of methanol-to-oil molar ratio, 1.5 wt% of KOH, within 1.5 h at an exceptionally low temperature of 35 °C. The kinetics of this mild reaction had found to be a pseudo-second order reaction, where the conversion of monoglycerides to fatty acid methyl esters (FAMEs) and glycerin at 35 °C attained a rate constant of 11.94 min⁻¹. The energies of activation (E_a) for the hydrolysis of triglyceride, diglyceride and monoglyceride were determined to be 43.19, 35.52 and 21.69 kJ/mol, respectively. Notably, the biodiesel met majority key quality specifications outlined in EN 14214, ASTM D6751 and MS 2008:2008, demonstrating the viability of this simplified method for biodiesel production. This approach contributes to circular bioeconomy by interlinking the waste valorisation with renewable energy production.