Single Step Biodiesel Production from Pongamia pinnata (Karanja) Seed Oil Using Deep Eutectic Solvent (DESs) Catalysts

This paper reports the production of biodiesel from Pongamia pinnata seed oil via single step process. The efficiency of deep eutectic solvents (DESs) synthesized from the mixture of choline chloride and para toluene solfonic acid (PTSA), was used with silica support (So-DES) and without support (Un-DES) as heterogeneous and homogeneous catalysts, respectively. The oil esterification with methanol and methyl tert-butyl ether as solvents was conducted. From the results, the optimum reaction conditions for esterification of P. pinnata seed oil with Un-DES are; catalyst loading 1 (wt%/v), reaction time was 120 min and temperature was 343 K. maximum total acid number (TAN) reduction obtained under these conditions was 0.57 mg/KOH/g and a corresponding biodiesel conversion of 97.53 %. The optimal reaction conditions for esterification with So-DES using methanol as solvent are; temperature of 353 K, catalyst loading was 5 (wt%/v) and reaction time was 240 min. The optimum TAN reduction obtained under these conditions was 1.42 mg/KOH/g with corresponding biodiesel conversion of 89.3 %. Catalysts reuse was between four to seven reuses for Un-DES and So-DES respectively. Physico-chemical properties studies indicated that, viscosity, density and calorific values were within acceptable standard limits. It could be concluded that, DES synthesized from choline chloride and PTSA either with or without supporting material, could effectively produce biodiesel with acceptable fuel quality via single step process.