Biodiesel production by lipase mediated transesterification of Acacia nilotica seed oil

Abstract

Biodiesel is becoming prominent among the alternative sources of energy due to its economic, environmental and social values. This work  investigated the possibility of using calcium alginate immobilized lipase from Pseudomonas aeruginosa for the production of biodiesel from Acacia nilotica seed oil. The physico-chemical properties of Acacia nilotica biodiesel were assessed. Methyl esters composition indicated the presence of  octadecenoic (69.14%), hexadecanoic (15.47%) and (7.92%) octadecanoic acid as dominant fatty acid methyl esters. The biodiesel produced had a specific gravity of 0.84, refractive index of 1.34 0.04 and viscosity 2.73 ± 0.15 Pa.S. The cetane number recorded was 32.81 ±0.10, calorific value 29.0 mJkg^-1, flash point 113^oC, while the cloud and pour points were 1.06^oC and 4.0^oC respectively. The iodine value was 187.6±0.60 gI₂/100 g, acid value 0.61±0.01/g, saponification value 189±1.00mgKOH/g and peroxide value 6.60±0.05 meq/kg. The observed characteristics of the biodiesel produced were largely in conformity with the ASTM and EN biodiesel standards.

Key words: Acacia nilotica: seed oil: transesterification: immobilized lipase