| Biodiesels were prepared from swill-cooked dirty oil, rubber seed oil and Jatropha curcasl L. oil respectively, then their oxidative stabilities were detected,and the compositions of the biodiesels before and after oxidation were analyzed by FTIR and GC-MS. The results showed that the oxidative induction periods of swill-cooked dirty oil biodiesel, rubber seed oil biodiesel and Jatropha curcasl L. oil biodiesel were 1.61 h, 0.81 h and 1.05 h, respectively, which could not reach 6 h of the national standard of biodiesel; the major component of biodiesel was fatty acid methyl ester, and the C=C—H group in fatty acid methyl ester disappeared after oxidation; the main fatty acid methyl esters in the three kinds of biodiesels were methyl palmitate, methyl linoleate, methyl oleate and methyl stearate, and the total contents of fatty acid methyl esters in the three kinds of biodiesels after oxidation declined from 93.07%,95.82%,97.68% to 77.23%,84.51%,63.66%;the composition of oxidated biodiesel was very complex containing different aldehydes, acids, ketones, alcohols and small molecular esters, and the content of methyl linoleate reduced greatly,which demonstrated that the oxidation of biodiesel was mainly the oxidation of unsatu rated fatty acid methyl esters with double bonds or triple bonds. |
