Bioprocessing of Jatropha curcas seed oil and deoiled seed hulls for the production of biodiesel and biogas

Abstract

Jatropha curcas seeds afford non edible oil seed source for biodiesel, therefore, production of biodiesel from this oil would avoid food versus fuel controversy. However, Jatropha seed oil contains higher amounts of free fatty acids (about 12%). Therefore this requires a two step acid-base catalyzed treatment for the trans-esterification to obtain biodiesel. However, the use of lipase enzymes affords the trans-esterification of seed oil in a single step only. Therefore, presently the research work was performed to study the trans-esterification of Jatropha seed oil by using lipase enzymes obtained from the two microbes i.e., Pseudomonas sp. and Rhizopus sp., respectively. The lipase enzyme obtained from Pseudomonas sp. was found to show more than ten times higher activity in comparison to that of Rhizopus sp. Thus, the use of Psedomonas sp. lipase also showed higher yields of biodiesel in comparison to that of Rhizopus sp. Bioprocessing of J. curcas seed oil by single step process was compared with the two step chemical process to obtain biodiesel. A comparison of the two processes has been drawn. The biodiesel obtained from the Jatropha oil seeds were characterized for physical properties like kinematic viscosity, density, flash point, pour point, acid number and water content. The residual seeds obtained after the recovery of oil were found to be good substrate for the biogasification to obtain biomethane. Bioprocesses for obtaining added value chemical from the byproduct glycerol are being developed currently. © 2012 Elsevier Ltd.