1H-NMR and FTIR validation of chemical transformation from Khaya Senegalensis oil to biodiesel and comparison between the biodiesel and Conventional diesel

Low oxidation stability and poor flow are common characteristics of crude vegetable oil and in similar renewable energy sources, that negatively impact on the oil application directly as fuel in diesel engines. Some chemical transformation such as transesterification, epoxidation of the crude oil is carried out, and conversion from crude oil to biodiesel is achieved. To monitor the changes from crude oil to biodiesel, techniques like Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR) are carried out. This study further the FTIR investigation on an earlier Khaya Senegalensis sample of crude oil and biodiesel by Ishaya et al., (2022), by carrying out NMR investigations. The results showed that both FTIR and NMR agrees on the presence of carboxylic site in the crude oil to support transesterification reaction. 1H-NMR spectrum (CH3 alkane at 0.9 ppm, α- CH2 alkane at 2.3 ppm, HC=CH alkene at 5.3 ppm, and H3C-O ester at 3.6 ppm) and FTIR spectrum (C-H alkane at 2922-2855 cm-1, C=C alkene at 1654 cm-1, C-O esters at 1244-1170 cm-1 ) of the Khaya Senegalensis biodiesel both agrees on the presence of alkanes, alkenes and esters chemical environments, that suggest chemical transformation had occurred in the triglyceride crude oil observed by (CH2OCOR at 4.11-4.27 ppm in 1H-NMR and C=O at 1744 cm-1, C-O-C alkanoate at 1095 cm-1 in FTIR). The 1H-NMR spectrum of conventional diesel suggest presence of short chains as compared to biodiesel that is made up of long chains esters. The 1H-NMR spectrum of Khaya Senegalensis biodiesel also identified esters that support low viscosity, high flash point and more energy per unit volume.