Extraction of lignin from tobacco stem using ionic liquid

Lignin only accounts for about 6% of total mass in tobacco stem, but it influences the harmful substances in the side stream smoke of cigarette in a significant way. Traditional researches focus only on the determination of lignin content. In the present work, we investigate four typical imidazolium-based ionic liquids for efficient extraction of lignin under mild conditions and 1-ethyl-3-methylimidazolium diethylphosphate ([Emim][DEP]) shows the best results. The pretreatment of stem using water at 80 °C for 30 min can not only remove most of the sugars but also loose the microfibers. The extractive rate of lignin reaches 85.38% at 150 °C for 4 h and the purity of lignin is 90.21%.