Increasing application for lignin due to its unique aromatic structures has encouraged the development of pretreatment techniques for lignin separation and recovery. In this work, the integration of microwave-assisted hydrothermal pretreatment (MW-HTP) and alkaline post-treatment was proposed for separating lignin from poplar wood and revealing its structural characteristics. Results showed that the yields of the lignins fractionated via the integrated treatment based on MW-HTP were increased up to 52.6%, and their associated sugars contents were clearly decreased to 0.19-0.09%, as compared to the fractionated lignins without the microwave pretreatment (29.8% and 0.29%). Interestingly, the integrated treatment based on MW-HTP promoted the cracking of β-O-4 ethers in the lignin macromolecules of poplar wood, resulting in the raise of their phenol OH groups up to 2.36 mmol/g. Overall, the fulfillment of this work will be conducive to improve the fractionation and efficient utilization of lignin in biorefinery industry.
Keywords: Hydrothermal pretreatment; Integrated treatment; Lignin; Poplar; Structural characteristics.
Copyright © 2021. Published by Elsevier B.V.