Investigating the Effect of Catalyst and Deep Eutectic Co-solvent on Purity of Biodiesel Produced from Linseed Oil

Nowadays, due to environmental concerns and the reduction in fossil fuel resources, biodiesel is being considered as a renewable alternative or supplement to fossil diesel. In this research, the transesterification method was used to produce biodiesel from low-cost and non-edible linseed oil in the presence of commercial calcium oxide as the catalyst. In addition, the time-consuming and costly calcination step was omitted and a deep eutectic co-solvent of choline chloride/glycerol (۲:۱) was used to activate the catalyst. The catalyst characterization was studied using X-ray diffraction(XRD) and Fourier transform infrared (FTIR). To ensure the formation of fatty acid methyl esters (FAME), the purity of FAME in the produced biodiesel was calculated using gas chromatography method. Then, the effect of two reaction parameters of the catalyst and the DES concentration on the FAME purity was investigated at a constant temperature of ۶۵ °C, stirring speed of ۵۰۰ rpm, reaction time of ۱۸۰ minutes and the methanol to oil molar ratio of ۹.۵:۱. Finally, the optimal catalyst and the DES concentration were obtained as ۱۰% and ۱۴%, respectively. The effect of temperature and time on the FAME purity was investigated and a kinetic study of the reaction suggested a pseudo-first-order reaction with a rate constant of ۰.۰۳۱۱   at ۶۵ °C and activation energy of ۲۲.۴۵ kJ/mol.