Complementary biodiesel combination from tung and medium-chain fatty acid oils

The complementary blending of tung oil biodiesel with coconut oil and palm kernel oil biodiesels was investigated to improve the biodiesel properties. Tung oil is considered a potential non-edible oil feedstock for biodiesel production. However, tung oil biodiesel has unfavorable fuel properties, including a high density, kinematic viscosity, and iodine value and low oxidation stability because of the high content of α-elaeostearic acid (C18:3). In contrast, medium-chain saturated fatty acid methyl esters (FAMEs) such as lauric acid methyl ester (C12:0) is the predominant component in palm kernel oil and coconut oil biodiesels. The palm kernel oil and coconut oil biodiesels exhibited a low density, kinematic viscosity, and iodine value as well as high oxidation stability, features that are complementary to the deficiencies of tung oil biodiesel. An optimum blending ratio obtained comprised the COME, PKME, and TME at a weight ratio of 20:20:60. Most of the fuel properties of the optimum biodiesel blend could meet the biodiesel specifications, with the exception of the oxidation stability. In addition, the multiple linear correlations between the properties of biodiesel blends and their FAME composition were established. Furthermore, the effectiveness of butylated hydroxyanisole (BHA), N,N′-di-sec-butyl-p-phenylenediamine (PDA), and tert-butylhydroquinone (TBHQ) at concentrations between 1000 and 20,000 ppm was investigated to improve the oxidation stability of the biodiesel blend.