ABSTRACT
Lignin dissolution plays an important role in the conversion process of lignin. This work focused on the lignin dissolution in a binary mixture of 1-butyl-3-methylimidazolium hydrogen sulfate([BMIM]HSO4) and water. To understand the lignin dissolution behavior in the binary mixture of [BMIM]HSO4/H2O, the molecular interactions of [BMIM]HSO4 and H2O were first investigated by simple methods based on the viscosity and UV spectra. Then three different lignin samples, enzymatic hydrolysis lignin, alkali lignin, and organosolv Lignin, were employed to investigate the dissolution ability of [BMIM]HSO4/water with different mass fraction of [BMIM]HSO4([BMIM]HSO4%). The molecular interactions and lignin solubility of [BMIM]HSO4/H2O strongly depended on the mass fraction of [BMIM]HSO4([BMIM]HSO4%). A turning point for the formation of bi-continuous system at [BMIM]HSO4% of 63% was observed by the changing trend of viscosity and UV absorption. [BMIM]HSO4/H2O with 60-90% of [BMIM]HSO4% had excellent ability to dissolve EHL, and achieved the maximum value at 70% of [BMIM]HSO4%. It was indicated that the bi-continuous [BMIM]HSO4/H2O was the most effective in lignin dissolution. Lignin was regenerated with a recovery rate of 94.29%. Compared the regenerated lignin and the raw lignin, [BMIM]HSO4 altered the arrangement structure of lignin without no changes in the chemical structures. This study provided ideas for the process design of lignin dissolution and conversion in the [BMIM]HSO4/H2O system.
Acknowledgements
This work was supported by the Natural Science Foundation of Jiangsu Provincial [Grant NO. BK20190156].
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No potential conflict of interest was reported by the author(s).
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Notes on contributors
Huamei Yang
Mrs Huamei Yang is an associate professor in School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou 221018, China. She has more than twenty years of experience in renewable energy such as biomass conversion, hydrogen production and energy applications.
Ziqin Chen
Miss Ziqin Chen is a student in School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou 221018, China. She is interested in fluid performance.
Kai Luo
Mr Kai Luo is a student in School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou 221018, China. His areas of interest include thermal storage, computational fluid dynamics, and energy applications.
Yunfei Liu
Miss Yunfei Liu is a student in School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou 221018, China. Her areas of interest include biomass conversion and application.
Mengjun Yu
Miss Mengjun Yu is a student in School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou 221018, China. His areas of interest include biomass conversion and energy applications.
Beilei Wang
Mr Beilei Wang is a student in School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou 221018, China. His areas of interest include fluid performance and biomass conversion.