The present study is focused on the quantification of glycerides and free fatty acid in oils extracted from various seeds for biodiesel production from Indian territory. A new method based on 1 H-and 13 C-NMR spectroscopic techniques was developed in order to estimate triglycerides (TG), diglycerides, monoglycerides, free fatty acids (FFA) and various other components such as para-substituted phenols, silylated methyl esters, aromatic acids, naphthalenes, etc. Iodine values of the extracted oils were estimated using the developed 1 H-NMR spectroscopic method, which was correlated with the TG content present in the sample. Results by the NMR method were validated by the blend preparation, fatty acid composition determined by the GC and from the iodine value of the samples. The developed method is direct, rapid and no sample treatment is required. The results from these comprehensive studies indicated that NMR spectroscopic technique is useful for the quantification of extracted oils and can be used effectively for the development and monitoring of biodiesel production and determining the fuel quality.
Although the concentration of nitrogen compounds in crude oil is relatively low, they can become more concentrated in petroleum distillates and poison the catalysts used in refining processes. They cause undesirable deposits, color formation and odor in products; they also contribute to air pollution and some are highly carcinogenic. The poisoned catalyst becomes deactivated for hydrodesulfurization and unable to remove sulfur from middle distillates. In order to understand the effect on catalytic processes, it is desirable to identify the nitrogen compounds in various petroleum distillates. This paper compares the nitrogen species profiles in different petroleum distillates using a nitrogen chemiluminescence detector. In addition, four different petroleum distillate samples from different refineries were analyzed to find the variation in their nitrogen profiles. The nitrogen compounds in petroleum distillate samples were identified as anilines, quinolines, indoles, and carbazoles and their alkyl derivatives. Quantitation was carried out against known reference standards. The quantitative data were compared to the total nitrogen content determined by elemental analysis.
A method for the determination of the iodine value in
biodiesel produced from algal and vegetable oils has been developed
by nuclear magnetic resonance (NMR) spectroscopy. The determination
of the iodine value is based on the average molecular weight of the
fatty acid methyl esters and the number of double bond, which are
calculated from 1H NMR spectra. The total methyl ester
content (% ME) was estimated using the integral value of the OCH3 group peak at 3.67 ppm and the α CH2 at
2.2 ppm. The results obtained from the 1H NMR method show
good correlation (r
2 = 0.9974) with the
traditional American Oil Chemists’ Society (AOCS) method. The 1H NMR method does not depend upon the nature of biodiesel
feedstock. It is applicable to all methyl biodiesel samples obtained
from different raw materials, including algal oils. The results show
that a higher iodine value indicates less oxidation stability, but
there is not a linear correlation between the iodine value and oxidation
stability of biodiesel.
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