Chromatography, spectroscopy and thermal analysis of oil and biodiesel of sesame (Sesamum indicum) − An alternative for the Brazilian Northeast

• The seeds were originated from the Brazilian Northeast.
• The sesame oil was extracted using mechanical method (filter-press).
• The samples were analyzed using thermogravimetric and spectroscopy techniques.
• The thermogravimetric data were utilized to determine the activation energy.

The brute oil obtained by sesame seed mechanical extraction and biodiesel obtained through transesterification with methyl and ethyl alcohol was analyzed by the use of the following techniques: gas chromatography coupled to mass spectrometer (CG/MS) and nuclear magnetic resonance of hydrogen and carbon (NMR 1H and 13C). The seeds were cultivated in Sousa city, located in the northeast of Brazil. The linoleic acid was found as major component of the oil followed by the oleic acid. The NMR spectra confirm the obtaining of the methyl and ethyl biodiesel. The thermal behavior of the oil and the biodiesel were determined by the use of thermogravimetric analysis (TG). The TG curves were obtained in three different heat rates (10, 20 e 30 °C.min−1) in oxidative atmosphere. The decomposition of the biodiesels occurred in only one-step. However, three steps were observed for the thermal degradation of the brute oil. These steps can be attributed to evaporation and/or decomposition of the triglycerides. The analysis of the thermogravimetric data allowed the determination of the thermodynamics parameters as pre exponential factor and activation energy. The average value of the energy activation for the methyl biodiesel was 67.54 ± 0.84 KJ mol−1 and for the ethyl biodiesel was 66.74 ± 0.75 KJ mol−1.