Castor-babassu biodiesel blends: estimating kinetic parameters by Differential Scanning Calorimetry using the Borchardt and Daniels method

The main objective of this study was to assess the kinetics of the deterioration of blends of babassu and castor biodiesel. The biodiesel samples were synthesized by catalytic transesterification and characterized for their main physical properties such as kinematic viscosity, density, acid number, ester content, and oxidation stability. Thermal profiles were carried out using the Differential Scanning Calorimetry technique as presented in the American Society for Testing and Materials (ASTM) E537 standard. Kinetic parameters were obtained using ASTM E2041 standard (Borchardt-Daniels method), following a statistical treatment from the ASTM E1970 standard. Among all samples, the pure castor biodiesel sample showed the highest extrapolated onset temperature (T-s), 214.92 degrees C, and lowest reaction rate [k(T)], 1.02x 10(-3)min(-1), indicating that this sample is more resistant to oxidation. On the other hand, the blend with the babassu/castor biodiesel mass ratio of 75/25 was the most prone to oxidize. Thus, castor biodiesel may be used as an additive to improve the oxidative stability of other sources of biodiesel, including babassu biodiesel.