Master of Science in Biological and Agricultural Engineering (MSBAE)


Biological and Agricultural Engineering

Document Type



In-situ transesterification (simultaneous extraction and transesterification) of Chinese tallow tree seeds into methyl esters using two microwave systems were investigated in this study. In the first part, utilizing a batch system, parameters tested were catalyst concentration (1-4 wt.%), solvent ratio (2-6 v/w), reaction time (15-60 min) and temperature (50-70°C). A high degree of oil extraction and efficient conversion of oil to biodiesel were found in the proposed range. The process was further optimized in terms of product yields and conversion rates using Dohlert optimization methodology. Based on the experimental results and statistical analysis, the optimal production yield conditions for this process were determined as: catalyst concentration of 1.74 wt.%, solvent ratio about 3 (v/w), reaction time of 20 min and temperature of 58.1°C. GC and H-NMR were used to profile the fatty acid methyl esters and reaction conversion, respectively. All methyl esters produced using this method met ASTM biodiesel quality specifications. For the second part, a continuous In-situ transesterification of the seeds using a microwave-assisted CSTR system was investigated with determination of kinetic parameters. A high production yield of 90.02% with 97.53% conversion rate was obtained in 24 min CSTR residence time at a methanol/hexane/CTT seed ratio of 3:3:1 (v/v/w), a microwave heating power of 290 W and 14 sec exposure time, reaction temperature of 60°C and sodium hydroxide catalyst loading of 4% wt. of oil. The experimental data fits the first order reaction kinetics. The values of rate constants at different temperatures and the corresponding activation energy were found out to be 0.083-0.087 min -1 and 1987.82 J/mol, respectively. The thermodynamic parameters values such as Gibbs free energy (ÄG), enthalpy (ÄH) and entropy of activation (ÄS) were also determined. The positive values of ÄG and small negative value of ÄH indicated that the reaction has an unspontaneous/endergonic nature and is slightly exothermic.



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Committee Chair

Boldor, Dorin



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Engineering Commons