Water effect on the characterization of 1-butyl-3-methylimidazolium hydrogen sulfate and lignin dissolution

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.

KEYWORDS:

• 1-Butyl-3-methylimidazolium hydrogen sulfate
• water
• lignin
• dissolution
• viscosity
• molecular interactions

Acknowledgements

This work was supported by the Natural Science Foundation of Jiangsu Provincial [Grant NO. BK20190156].

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the the Natural Science Foundation of Jiangsu Provincial [BK20190156].

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.