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Effects of Antioxidants on the Cetane number, Viscosity, Oxidation Stability, and Thermal Properties of Biodiesel Produced from Nonedible Oils

Authors

  • Thomas T. Kivevele,

    Corresponding author
    1. Department of Mechanical Engineering, Tshwane University of Technology, Private Bag X680, Pretoria 0001 (South Africa)
    • Department of Mechanical Engineering, Tshwane University of Technology, Private Bag X680, Pretoria 0001 (South Africa)
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  • Prof. Zhongjie Huan

    1. Department of Mechanical Engineering, Tshwane University of Technology, Private Bag X680, Pretoria 0001 (South Africa)
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Abstract

Poor oxidation stability of biodiesel is the central problem associated with its commercial acceptance. To enhance the practical feasibility of biodiesel, antioxidants are added to increase its storage stability. It is quite possible that these additives may affect other basic fuel properties of biodiesel. Therefore, the present study investigated the effects of antioxidants on the basic fuel properties of biodiesel produced from nonedible oils of African origin (Moringa oleifera, Jatropha curcus, and Croton megalocarpus). Four antioxidants: 1,2,3-trihydroxybenzene (pyrogallol, PY), 3,4,5-trihydroxybenzoic acid (propyl gallate, PG), 2-tert-butyl-4-methoxyphenol (butylated hydroxyanisole, BHA) and 2,6-di-tert-butyl-4-methylphenol (Butylated Hydroxy Toluene, BHT) were investigated for their effectiveness in oxidation stability. The results showed that PY and PG were more effective than BHA and BHT. The most effective antioxidant (PY in this study) was was studied further for its effects on other basic fuel properties of biodiesels such as kinematic viscosity, cetane number, and thermal properties. It was observed that the kinematic viscosity was reduced at lower concentrations of antioxidant additives (500 ppm) and slightly increased at high concentrations (1000 ppm) but lower than that of pure biodiesel. The cetane number was slightly increased at both 500 and 1000 ppm of PY antioxidant content. The effects of the antioxidant on the thermal properties were not clearly observed. Therefore, it can be concluded that adding antioxidants to biodiesel lengthens increases the storage stability and also improves the kinematic viscosity, thermal properties, and cetane number as an added advantage.

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