Insight into the dissolution behaviour and rheological characterisation of lignin in 1-butyl-3-methylimidazole bisulphate-ethanol system

ABSTRACT

Lignin dissolution and the fluid behaviour of reaction systems play important roles in the conversion rate of lignin. This study investigated the solubility of enzymatic hydrolysis lignin (EHL) in 1-butyl-3-methylimidazole bisulphate ethanol solutions ([BMIM]HSO₄/ethanol) and the dynamic shear rheological characterisation of EHL-[BMIM]HSO₄/ethanol. Different with [BMIM]HSO₄/water, [BMIM]HSO₄/ethanol exhibited excellent abilities to dissolve EHL at [BMIM]HSO₄% 20%–90%, with the maximum EHL solubility obtained at 40%–70%. The dynamic shear rheological characterisation strongly depended on temperatures, [BMIM]HSO₄% and EHL%, exhibited as pseudoplastic fluid at higher [BMIM]HSO₄% and EHL%, and Dilatant fluid at lower [BMIM]HSO₄% and EHL%. Adjusting an appropriate [BMIM]HSO₄% and EHL%, EHL-[BMIM]HSO₄/ethanol was Newtonian fluid with the viscosity stable. EHL was regenerated from EHL-[BMIM]HSO₄/ethanol without obvious changes in the chemical structure and thermal behaviour. This study provided ideas for the design of the [BMIM]HSO₄/ethanol system and the optimisation of conversion processes for the economic utilisation of lignin.

KEYWORDS:

• Lignin
• 1-butyl-3-methylimidazole bisulphate-ethanol system
• dissolution behaviour; rheological characterisation

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by the Natural Science Foundation of Jiangsu Province [Grant NO. BK20190156], and the Applied Basic Research Programs of Xuzhou [Grant NO. KC19048].