7. Biodiesel analysis
7.1. Physical and fuel properties
The fuel properties of synthesized Nahor oil biodiesel were determined according to the American Society for Testing and Materials (ASTM) and the results are presented in Table 4 along with the recommended values for biodiesel (ASTM-D6751). It can be seen from the table that the Nahor oil biodiesel produced in the presence of Li loaded egg shell derived catalyst has fuel properties within the limits of ASTM D6751for biodiesel.
7.2. NMR studies
7.2.1. 1H NMR analysis
Fig. 11. 13C NMR spectrum of (a) Nahor oil feedstock and (b) Nahor oil biodiesel.
Biodiesel produced in the transesterification of Nahor oil was characterized by 1H NMR spectroscopy (Fig. 10). The frequency range between δ = 3 and 5 ppm (where δ is chemical shift) represents the resonances of the molecules containing oxygenates or the methoxy groups of FAME. The major difference between the 1H NMR spectra of the feedstock and resulting methyl ester formation is the disappearance of glyceride protons around 4.0–4.3 ppm and appearance of methyl ester protons around 3.6 ppm. As can be seen from Fig. 10(b) a single peak appears near 3.57 ppm and a multiplet peak corresponding to α-CH2 protons at 2.28 ppm appears which is related to methoxy group. These peaks confirm the presence of fatty acid methyl ester (FAME) in biodiesel. Biodiesel production is also confirmed from the decreasing peaks at 4.0–4.3 ppm which is due to the glyceride protons, Fig. 10(b). A triplet near 0.8 ppm in the spectrum appears for the
terminal methyl protons, a strong signal at 1.2 ppm is related to the methylene protons of carbon chain, multiplet around 1.6 is due to the β-carbonyl methylene protons and the peaks around 5.3 ppm are assigned to the olefinic hydrogens respectively [26–30].
6.1.1. 13C NMR analysis
Fig. 11(a and b) represents the spectrum of 13C NMR of the Nahor oil and Nahor oil biodiesel respectively. The peaks at 61.94 and 69.09 ppm in the NMR spectrum of the Nahor oil were attributed to the OCH and OCH2 functional groups of TAG. These two peaks disappear when methyl esters are formed and a new peak at 50.68 ppm appears which is associated with OCH3 carbon Fig. 11(b). Characteristic peak of ester carbonyl (COO) appears at 173.33 ppm while the peaks around 131.02 and 126.46 ppm indicate the presence of unsaturated fatty acids in the 13C NMR spectrum of biodiesel. In the spectral region from (35–11 ppm) the peak from 28.88 to 29.40 ppm is related to CH2CH2 group of FAME. Signal at 13.59 ppm was ascribed to the CH3 group of the methyl ester formed [27,29,31].
7. Conclusion
Investigation on Li doped egg shell derived CaO is carried out for the transesterification of M. ferrea Linn (Nahor oil) which is a nonedible feedstock. Under the optimum reaction condition of 2% Li loading, 5 wt.% catalyst amount, 10:1 methanol to oil ratio, 4 h reaction time and 65 °C reaction temperature, maximum biodiesel conversion was achieved. The catalyst was reusable and the drop in activity is attributed to the coverage of the catalyst surface by the product formed during the reaction. The initial catalytic activity is attributed to the formation mixed Li–Ca phase along with the presence of Li2O and CaO.
Acknowledgment
One of the authors, Jutika Boro is highly grateful to the University Grant Commission, Government of India for providing financial assistance in the form of Rajiv Gandhi National Fellowship.