Abstract: For decreasing the cost of biodiesel and utilizing the by-product glycerol, as by-product 75% raw glycerol instead of pure glycerol monostearin was synthesized, extracted and recrystalized with glycerol instead of benzene. Central combination design method was applied to design the test. The optimal conditions: the mole ratio 2.8, the reaction temperature 240 ℃ and the reaction time 1.8 h. After leaching and riming with ethanol, monostearate content was 97.97%, which can be used as food additive.

Key words: biodiesel, by-product, raw glycerol, central combination design, monostearin