Esterification Deacidification of Zanthoxylum Bungeanum Seed Oil

Effects of mole rate of methanol/oil, reaction time and technology on the free fatty acid ( FFA) level decrease of Zanthoxylum bungeanum seed oil with sulfuric acid as catalyst was investigated. Results show that, the acid level decreases with the mole rate of methanol/oil increases when the sulfuric acid is 2% based on the weight of Zanthoxylum bungeanum seed oil and reacting at 60°C for 2h. When the mole rate is 20~35∶1, the final acid value is less than 2mgKOH/g which meets the requirement for biodiesel production. When the mole rate is 25∶1, with sulfuric acid dosage 2% and reacting at 60°C, the acid value decreases fast at the beginning of the acid esterification. The acid value of ZSO was reduced to 1.56 mg KOH/g from 78.91 mg KOH/g by only one-step acid-catalyzed esterification with methanol-to-oil molar ratio 30:1, H2SO4 2%, temperature 60°C and reaction time 60 min, which was selected as optimum for the acid-catalyzed esterification.