Cleaner production of catalytic thumba methyl ester (Biodiesel) from thumba seed oil (Citrullus Colocyntis) using TiO2 nanoparticles under intensified hydrodynamic cavitation

This work explores the feasibility of titanium dioxide (TiO2) for its application in thumba oil transesterification, where a reactor was integrated with hydrodynamic cavitation (HC). TiO2 nanoparticles were synthesised using the ultrasound-assisted sol-gel method by varying the operating conditions. The synthesised TiO2 was found to be in the pure anatase phase. The smallest particle diameter was found to be 8.42 nm under optimised conditions. The consequences of various operating variables (inlet pressure and HC system geometry) on the triglyceride conversion were studied in the HC system. The Gas chromatography (GC-FID) analysis of biodiesel confirmed its synthesis. Orifice plate B with three 2-mm holes resulted in the highest cavitational yield of 9.1 x 10(-6) mol.L/J at 5 bar. Under optimised process parameters, a maximum conversion of 71.8% was achieved at 5 bar within 1 h in an HC system. The experimental data reasonably fit 1st order reaction kinetics concerning alcohol and 2nd order kinetics concerning thumba oil. The energetic analysis shows that the highest energy consumption was 16 kWh/m(3), much less than the conventional method at 500 kWh/m(3). Thumba methyl ester prepared using this novel accelerated technique exhibited time savings and energy coherency, building the operation more resource efficient.

Automated summary

This study explores the application feasibility of titanium dioxide (TiO2) in thumba oil transesterification. TiO2 nanoparticles were synthesized using the ultrasound-assisted sol-gel method, with the smallest particle diameter of 8.42 nm achieved under optimized conditions. The effects of various operating variables on the triglyceride conversion in the hydrodynamic cavitation (HC) system were investigated. The highest conversion of 71.8% was achieved within 1 hour at 5 bar in the HC system under optimized process parameters. The use of this novel accelerated technique for thumba methyl ester preparation offers time and energy savings, making the operation more resource efficient.