Optimal Process Conditions for Enhanced Co-Solvent Based Transesterification of Tigernut Oil

Abstract

A two-step transesterification of tigernut oil with methanol in di-ethyl ether (co-solvent) was carried out, and a four-factors-four-levels central composite design optimization study was also carried out to maximize the yield of the biodiesel. A maximum yield of 89.3% was obtained under the optimal transestrification conditions of methanol-to-oil volume ratio of 7:1, catalyst loading of 1.0 w/w %, temperature of 36 oC and reaction time of 30 minutes. Furthermore, analysis of the biodiesel produced showed that its kinematic viscosity (5.58 mm2/s) and pour point (6 °C) fell within the ASTM range, while its cloud point (14 °C) was very close to the ASTM range. Its flash point of 185 °C was however, on the high side. Additionally, characterization of the tiger nut oil biodiesel using GC-MS confirmed the presence of methyl ester on the biodiesel sample.