Improved biodiesel from palm oil using lipase immobilized calcium alginate and Irvingia gabonensis matrices

Abstract

Background: Lipase is an important microbial enzyme and biocatalyst in biodiesel production. The study investigated fuel properties of biodiesel produced from palm oil (PO) using lipase immobilized on Irvingia gabonensis and calcium alginate. Results: Biodiesel yield from PO using free and immobilized lipases was highest at 35 °C and pH 7, with product yield using calcium alginate-immobilized lipase, CAIL (94.42, 96.9%) higher than using Irvingia gabonensis-immobilized lipase, IGIL (92.54, 95.8%). Biodiesel produced using immobilized lipases had similar pour point, cloud point, and kinematic viscosity, and they possessed improved fuel properties compared to free lipase biodiesel in terms of densities at 15 °C and flash point. Pour points, flash point, and kinematic viscosity of biodiesel produced using CAIL and IGIL met American and European Standards but density at 15 °C and cloud points are below both standards. CAIL and IGIL biodiesel had similar fatty acid methyl ester (FAME) compounds and consisted more of unsaturated fatty acids (hexadecanoate, 9-octadecenoate, octadecanoate, dodecanoate, and 9,12-octadeca-dienoate) than obtained in biodiesel from free lipase. IGIL and CAIL were re-used in 8 and 12 cycles respectively, with > 90% biodiesel yield achieved in four and 11 cycles. Conclusions: The study showed that lipase immobilized on Irvingia gabenensis and calcium alginate and used in biodiesel production retained high enzyme activity and biodiesel yield in repeated cycles.