Abstract

An integrated approach is needed to make biodiesel production cost-effective and a suitable choice of fuel. This study was therefore designed to utilize the seed cake of Vitellaria paradoxa obtained during oil extraction stage for the synthesis of a solid acid catalyst capable of hydrolysis and/or esterification reaction. The seed cake was pyrolyzed in an inert tube furnace at 420°C for 5 h, and then sulfonated in fuming sulphuric acid (15 wt.%) at 150°C for 10 h to obtain a biomass-derived catalyst. The catalyst was characterized by elemental analysis, FT-IR spectroscopy, X-ray diffraction (XRD) spectroscopy and total acid density. The hydrolytic activity of the catalyst was performed using vegetable oil obtained from V. paradoxa biomass and the reaction was optimized using a randomized central composite rotatable design (CCRD). The optimization results showed that catalyst derived from seed cake of V. paradoxa was active in hydrolysis reaction and a conversion of 34.3% was obtained and it was also observed that reaction time and weight of catalyst have significant effect on the reaction. When the catalyst was further employed for esterification of free fatty acids in V. paradoxa oil, higher conversion (70%) was achieved at a prescribed reaction condition. The approach of utilizing the waste generated during oil extraction from plants could make the process much greener when viewed from the context of resource efficiency and has the potential to kick start the commercialization of biodiesel production especially in developing countries.

Keywords: Vitellaria paradoxa; Solid acid catalyst; Hydrolysis; Esterification; Biodiesel; Optimization