Biodiesel synthesis from palm fatty acid distillate using enzyme immobilized on magnetic nanoparticles

The present study deals with the esterification of palm fatty acid distillate (PFAD) using immobilized lipase on magnetic nanoparticles (MNPs) to produce biodiesel in a cleaner and more environmentally friendly way. Commercially available lipase CALBEX was used for immobilization of lipase on MNPs. The effect of various reaction parameters including the methanol-to-PFAD molar ratio, biocatalyst loading, reaction temperature, and agitation speed was examined using a one-factor-at-a-time approach. Maximum PFAD conversion of 82.74% was achieved under mild reaction conditions, with a methanol-to-PFAD molar ratio of 1.6:1, biocatalyst loading of 8 wt% (lipase content 0.45 wt%), agitation speed of 150 rpm, reaction temperature of 50 °C, and reaction time of 10 h. The catalytic activity of MNP-CALBEX was compared with commercial Amberlyst-15 under similar reaction conditions. It was observed that MNP-CALBEX achieved 2.6-fold higher conversion than Amberlyst-15. The reusability of the immobilized biocatalyst was also tested to determine cost feasibility. It was observed that the immobilized biocatalyst could be used up to five cycles, with residual conversion of 80.19% in the fifth cycle.