Evaluation of antioxidants on the thermo-oxidative stability of soybean biodiesel

Journal of Thermal Analysis and Calorimetry (Impact Factor: 2.21). 07/2012; DOI: 10.1007/s10973-012-2650-6

ABSTRACT This work shows the evaluation of three anti-oxidants (2,6-di-t-butyl-4-methylphenol (BHT)—synthetic antioxidant, hydrogenated cardanol (HC), and alkyl hydrogenated cardanol (AHC)—both derived from cashew nut shell liquid) on the thermo-oxidative stability of the soybean biodiesel. The antioxidants were added at con-centrations of 200, 300, and 400 ppm, and the oxidative stability of the biofuel with and without antioxidants were investigated by thermogravimetric analysis (TG-DTG and IPDT) and Metrohm 743 Rancimat per the EN 14112 method. The results showed that all antioxidants contrib-uted for the thermo-oxidative stability of the soybean biodiesel as follows: soybean biodiesel \ soybean biodie-sel ? BHT \ soybean biodiesel ? HC \ soybean biodie-sel ? AHC. In the Rancimat method, the results showed that the antioxidants influenced the biodiesel stability with an increase of at least 71 %.

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    ABSTRACT: The vegetable oil, fats and their biodiesel suffer with the drawback of deterioration of its quality during long term storage unlike petroleum diesel due to large number of environmental and other factors making the fuel stability and quality questionable. There are various types of stabilities like oxidation, storage and thermal, playing key roles in making the fuel unstable. The present paper is an attempt to review the work done so far on the thermal stability of biodiesel and their blends with diesel under different conditions. The mechanism of thermal deterioration of vegetable oils, various methods of stability measurement including a new proposed method based on Karl Fischer coulometer, an alternative to conventional Rancimat test has been discussed. No correlations have been found in the literature among the results of various methods used. The effect of antioxidants on the stability parameters has also been discussed. TGA/DTA has been found as an effective method to check the deterioration of oil with respect to temperature using activation energy and order of reaction as the parameter to monitor the deterioration of oil.
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May 16, 2014