Influence of Antioxidants Type and Concentration On the Oxidative Stability of Castor Oil FAME

The oxidation stability of castor oil fatty methyl ester (FAME), doped with four different phenolic antioxidants, was evaluated using a rapid method of thermal and air-contact degradation. The methodology is based on the induction times observed when the samples are contacted with pure oxygen at elevated pressures and temperatures. The pressure drop in a sample exposed to pure oxygen at 700 kPA and 140ºC is used to evaluate the oxidation stability of castor oil FAME. The use of antioxidants increased from 6-15 times the stability of castor oil FAME, with the best results indicating the use of BHA (butylated hidroxyanisol) at 2000 ppm for this type of oil. Comparison with previously published reports indicate that, in general, the use of this rapid test does indeed represent the behavior normally observed for tests using available standard methods (Rancimat) and may save time in evaluating biodiesel samples and antioxidants performance.