Thermophysical Characterization of the Seeds of Invasive Chinese Tallow Tree: Importance for Biofuel Production

The limited supply of traditional fossil based fuels, and increased concern about their environmental impact has driven the interest in the utilization of biomass based energy sources, including those that are underutilized or otherwise nuisance species such as Chinese tallow trees (Triadica sebifera [L.]). This species is a prolific seeds producer, and this paper shows that they contain more than 50% lipids by mass that are suitable for conversion into biodiesel. We present here, for the first time, the seeds' thermophysical properties important for biofuel production. The seeds were characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and ultimate analysis; their thermal conductivity, thermal diffusivity, and specific heat were determined. The characterization results were correlated to fatty acid composition and lipid content for whole seeds and individual layers, as well as to the protein, hemicellulose, cellulose, and lignin content. The TGA analysis indicated the presence, in addition to lipids, of hemicellulose, cellulose, lignin, and proteins, depending on the layer analyzed. Thermal conductivity and specific heat were, respectively 0.14 +/- 0.007 W/mK and 3843.5 +/- 171.16 J/kgK for wax, 0.20 +/- 0.002 W/mK and 2018.7 +/- 5.18 J/kgK for shells, 0.13 +/- 0.0 W/mK and 1237 +/- 3.15 J/kgK for internal kernel, and 0.13 +/- 0.000 W/mK and 2833.9 +/- 104.11 J/kgK for whole seeds. These properties and characterization method can be further used in engineering analysis used to determine the most optimum processing method for production of biofuels from this feedstock.