Biodiesel Potential of Nonfood Plant Resources from Tsinling and Zhongtiao Mountains of China

Forty-nine wild oil plants which are abundant in the Tsinling and Zhongtiao Mountains were investigated and screened as raw material for biodiesel production. The oil content was tested and found to be greatly variable, ranging from 10 to 62.8 %. Fatty acid profiles of their vegetable oils were analyzed, and their acid value, saponification number, and iodine value were found to range from 1.6 to 61.3 mg KOH/g, 128.6 to 225.9 mg KOH/g, and 54.3 to 120.9 g I₂/100 g, respectively. Cetane number, kinematic viscosity, specific gravity, high heating values, and cold filter plugging point of the 49 vegetable-oil methyl esters (MEs) were empirically calculated and were found to vary from 38.8 to 66.6, 2.9 to 4.2 mm²/s, 841.4 to 883.8 kg/m³, 39.0 to 47.5 kJ/g, and -14.3 to 13.2 °C, respectively. Almost half (25 species) of all the sampled resources were found to be suitable for biodiesel production since the profiles of their vegetable-oil MEs met the major specifications of Chinese and European Union biodiesel standards, GB/T20828 and EN-14214, respectively. Grey relational analysis was used during the optimum-species screening process. The difference between the individual species and the artificial designed ideal species (the best biodiesel plant type in this paper) was calculated and evaluated with the help of grey relational grade, which varied from 0.467 to 0.686. Finally, the selected plants, Prunus salicina Linn. and Amygdalus davidiana (C.) C. de Vos, were considered as the optimal feedstock for biodiesel production.