Novel approach of esterification process using heterogeneous catalyst in biodiesel synthesis from waste cooking oil

Esterification process using heterogeneous catalyst in biodiesel synthesis from waste cooking oil (WCO) was investigated. In this study, heterogeneous catalyst TiO2 P25 was used to replace homogeneous acid catalyst in esterification process. Ultrasonic stirring was also used in esterification process to increase reaction rate with low energy. WCO was purified through filtration and bleaching to remove impurities and recover the colour of oil. After purification, esterification was conducted with photo-reactor that consisted of ultrasonic bath and ultraviolet lamp, which were installed around reaction mixture in order to activate TiO2 P25, instead of using acid catalyst and mechanical stirring. Esterification process were carried out at different TiO2 P25 loading, reaction time and ratio molar of oil and methanol. The samples were examined with titration method to obtained FFA content before and after esterification. Esterification process was followed with trans-esterification process to produce fatty acid methyl ester (FAME) or biodiesel. The maximum conversion of FFA was found at 45.2% with following operation condition: 0.25 wt% TiO2, 2 hours' reaction time, and 1:24 molar ratio of oil and methanol. Esterification process with heterogeneous catalyst TiO2 P25 and ultrasonic stirring has been proved to be successfully reduce FFA content of WCO so it can produce high quality of biodiesel which in accordance with the SNI Biodiesel 7182:2015