Optimization of accomplishing oil extraction and biodiesel synthesis by single-step technique from Xanthoceras sorbifolia bunge kernel

Abstract: The biodiesel was synthesized after the oil extraction and pretreatment, which was relatively complex in production and separation process. The separation cost was very large. That will be greatly reduced when the biodiesel was synthesized from the crude oil. The single-step technique was studied on the synthesis of biodiesel from Xanthoceras sorbifolia kernel in this study, using petroleum ether as extraction agent and methanol as synthesis agent. The oil extraction and ester exchange reaction was conducted under water bath heating and magnetic stirring conditions with sodium hydroxide as the catalyst. The single-step technique was investigated to accomplish oil extraction and biodiesel synthesis from Xanthoceras sorbifolia bunge kernel using central composite design. The predictive model of polynomial quadratic equation was established with Design Expert software. In the model, temperature, petroleum ether amount, methanol amount and sodium hydroxide amount were independent variables and biodiesel yield was response value. The results showed that the influencing degree of the four factors on biodiesel yield was petroleum ether amount > methanol amount > the temperature of extraction and reaction >sodium hydroxid amount. The influencing degree of the interaction between the factors on biodiesel yield was as follows: methanol amount and sodium hydroxid amount > the temperature of extraction and reaction and sodium hydroxid amount > the temperature of extraction and reaction and petroleum ether amount > petroleum ether amount and sodium hydroxid amount > the temperature of extraction and reaction and methanol amount > petroleum ether amount and methanol amount. The model could not only predict the biodiesel synthesis rate but also calculate oil recovery. The results showed that the optimal temperature of extraction and reaction was 77℃, petroleum ether amount was 6:1 mL/g, methanol and sodium hydroxide were 12% (mL/g) and 0.3% (g/g) of Xanthoceras sorbifolia bunge kernel amount respectively. Under these conditions, the biodiesel yield was 65.44%. The major components of biodiesel were methyl palmitate, methyl oleate, methyl linoleate, methyl linolenate and methyl erueate. The method provides a reference for oil extraction and biodiesel synthesis from Xanthoceras sorbifolia bunge kernels.