Reactive extraction and in situ self-catalyzed methanolysis of germinated oilseed for biodiesel production

Abstract

Compared with conventional production of biodiesel from oilseeds, in situ reactive extraction of oilseeds with acyl acceptors is an attractive approach, which consists of sustainable, economically attractive biotechnological processes for biodiesel synthesis. In this study, the presence of lipase activity in germinating oilseeds was detected and the lipase activity increased to a maximum after 4 days of germination. At that time, the germinated seeds featured an only slightly lower oil content relative to the ungerminated seeds. As such, an environmentally friendly and low-cost in situ self-catalytic process for biodiesel production was developed. The biodiesel was prepared by reactive extraction of germinated Jatropha curcas L. seeds with methanol without any other catalyst added. In this process, n-hexane was used as reactive extraction solvent. The highest fatty acid methyl esters (FAMEs) yield of 87.6% could be achieved under the optimum conditions: a n-hexane/germinated seed ratio of 2.5 ml g⁻¹, a methanol/germinated seed oil (contained approximately 90% FFA) molar ratio of 1.5 : 1, a reaction temperature of 35 °C, a germinated seed water content of 2.9% and a reaction time of 8 h. This simple reactive extraction process without additional catalyst can be a potential route for biodiesel production, which may greatly reduce the processing steps and costs.