Valorization of mixed radish seed oil and Prunus armeniaca L. oil as a promising feedstock for biodiesel production: Evaluation and analysis of biodiesels

A blend of radish oil (RO) and apricot kernel oil (AKO) was transesterified with methanol, ethanol, and their equivalent mixture, to yield methylic biodiesel (MBD), ethylic biodiesel (EBD), and methylic/ethylic biodiesel (MEBD), respectively with the refining of the so-developed fuels through adsorption onto the activated carbon prepared by ZnCl2 activation of apricot shells. The best conversion of RO-AKO blend to MBD (96.12 +/- 1.25%) and MEBD (94.23 +/- 2.22) was attained at KOH concentration, 0.75% w/w of oil, alcohol/oil molar ratio, 6/1, mixing intensity, 600 rpm, reaction temperature, 60 degrees C, and 45-min reaction period, whereas the best conditions that produced the highest yield of EBD (95.19 +/- 2.0 %) were KOH concentration, 1.0 KOH % w/w of oil, ethanol/oil molar ratio, 8/1, mixing intensity, 600 rpm, reaction temperature, 65 degrees C, and 75-min reaction period. The Fourier-transform infrared spectroscopy and H-1 nuclear magnetic resonance confirmed formation of the alkyl esters from the RO-AKO blend. The quality of MBD, EBD, and MEBD obtained from the RO-AKO blend was evaluated and found comparable with the American Society for Testing and Materials (ASTM) D6751 standards. Additionally, blending of MEBD with petrodiesel was possible, and properties of the blends were in accordance with those established by ASTM D7467-17. The methanolysis of the RO-AKO mixture followed the pseudo-first-order kinetics with activation energy of 27.27 kJ mol(-1). In conclusion, the RO-AKO mixture could be low-cost feedstock for biodiesel production. Moreover, apricot shells could be exploited as a priceless and suitable adsorbent for the adsorption of impurities found in the crude alkyl esters for its high surface area.