Physicochemical Characterization of Candlenut (Aleurites moluccana)-derived Biodiesel Purified with Deed Eutectic Solvents

A high-oil candlenut (Aleurites moluccana)-derived biodiesel was purified using new generation solvents called Deep eutectic solvents (DESs) and physicochemical properties of the purified biodiesel were assessed according to the accepted international standards for biodiesel (ASTM D6751; EN 14214). Binary and ternary choline chloride-based DESs containing glycerol and ethylene glycol as hydrogen bond donors were synthesized. The results of the investigation showed that the quality of DESs-purified biodiesel generally improved compared with the unpurified biodiesel and fulfilled the accepted standard limits for biodiesel except carbon residue and oxidation stability properties. Choline chloride/ethylene glycol (ChCl/Eg, 1:2 molar ratio) having a DES/biodiesel ratio of 1:1 (DES2-11) has enhanced the Fatty Acid Methyl Ester (FAME) content of unpurified biodiesel from 81.89% to 98.13%, and the oxidation stability from 2.36 h to 3.06 h. 1H NMR examination showed the successful synthesis of DESs; GC-MS analysis of candlenut oil and its biodiesel revealed oil and fatty acid methyl ester compositions, respectively. The similarity in FAME compositions between DESs-purified and unpurified biodiesel as revealed through GC-MS examination suggests the selective removal of impurities and the efficiency of DESs in improving the quality of candlenut-derived biodiesel.