Kinetic and thermodynamic parameters of volatilization of biodiesel from babassu, palm oil and mineral diesel by thermogravimetric analysis (TG)

• Published in: Journal of thermal analysis and calorimetry 2013, Vol.111 (1), p.155-160
• Main Authors: Oliveira, L. E., Giordani, D. S., Paiva, E. M., De Castro, H. F., Da Silva, M. L. C. P.
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Analysis; Analytical Chemistry; Applied sciences; Biodiesel fuels; Biomass energy; Chemistry; Chemistry and Materials Science; Energy; Exact sciences and technology; Fuels; Inorganic Chemistry; Measurement Science and Instrumentation; Miscellaneous; Physical Chemistry; Polymer Sciences; Quality control; Thermodynamics
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-011-2163-8

The boiling point and volatility are important properties for fuels, as it is for quality control of the industry of petroleum diesel and biofuels. In addition, through the volatility is possible to predict properties, such as vapor pressure, density, latent heat, heat of vaporization, viscosity, and surface tension of biodiesel. From thermogravimetry analysis it is possible to find the kinetic parameters (activation energy, pre-exponential factor, and reaction order), of thermally simulated processes, like volatilization. With the kinetic parameters, it is possible to obtain the thermodynamic parameters by mathematical formula. For the kinetic parameters, the minor values of activation energy were found for mineral diesel ( E  = 49.38 kJ mol −1 ), followed by babassu biodiesel ( E  = 76.37 kJ mol −1 ), and palm biodiesel ( E  = 87.00 kJ mol −1 ). Between the two biofuels studied, the babassu biodiesel has the higher minor value of activation energy. The thermodynamics parameters of babassu biodiesel are, Δ S  = −129.12 J mol −1  K −1 , Δ H  = +80.38 kJ mol −1 and Δ G  = +142.74 kJ mol −1 . For palm biodiesel Δ S  = −119.26 J mol −1  K −1 , Δ H  = + 90.53 kJ mol −1 and Δ G  = +141.21 kJ mol −1 , and for diesel Δ S  = −131.3 J mol −1  K −1 , Δ H  = +53.29 kJ mol −1 and Δ G  = +115.13 kJ mol −1 . The kinetic thermal analysis shows that all E , Δ H , and Δ G values are positive and Δ S values are negative, consequently, all thermodynamic parameters indicate non-spontaneous processes of volatilization for all the fuels studied.