Methyl ester synthesis of Pistacia khinjuk seed oil by ultrasonic-assisted cavitation system

Synthesis of biodiesel from a non-edible source as Pistacia khinjuk seed oil via ultrasonic cavitation (UC) system is reported in this study. A heterogeneous catalyst sulphated tin oxide impregnated with silicon dioxide (SO42-/SnO2-SiO2) was employed during the transesterification reaction in an UC reactor. Parametric optimisation results revealed the maximum Pistacia khinjuk methyl ester (PiKME) yield was 88 wt.% at reaction time of 50 min, amplitude of 50%, catalyst amount of 3.5 wt.% and molar ratio of 13:1 (alcohol:oil). Performance of UC at optimised values was compared with mechanical stirring (MS). UC proved advantageous over MS with 3 times more time efficient. Hence, the superiority of UC over MS was established. About 3.2 fold higher reaction rate constant using UC (0.029 min−1) compared to MS (0.009 min−1). PiKME production via UC can potentially subsidise the overall cost of production by having 3.2 fold higher reaction rate constant than MS. PiKME met most of the fuel properties enlisted in EN14214 and ASTM D6751 standards.