Understanding the dissolution of hemicellulose in ionic liquids (ILs) is important in order to explore efficient utilization of ILs for fractionating lignocellulose and extracting hemicellulose. In this study, three ILs, namely 1-butyl-3-methylimidazolium chloride (BmimCl), 1-butyl-3-methylimidazol-ium bromide (BmimBr), and 1-butyl-3-methylimidazolium iodide (BmimI), were used as solvents to dissolve bamboo hemicellulose over the temperature range of 80 °C to 150 °C. Representative hemicellulose with a solubility higher than 9.0 g/100 g IL was regenerated and characterized. The interaction between the hemicellulose and ILs was evaluated using carbon-13 nuclear magnetic resonance. The results showed that the solubility of hemicellulose in the ILs was in the following order: BmimCl > BmimBr > BmimI. Though moderate degradation of the hemicellulose possibly occurred during dissolution, the main chain of the hemicellulose was almost unchanged. The enhanced solubility of the hemicellulose was because of the formation of hydrogen bonds between the hydroxyl proton of the hemicellulose and anion of the ILs.
Bibliographical noteFunding Information:
This work was supported by the Natural Science Foundation of China (21666022) and the Natural Science Foundation from the Ministry of Education of Jiangxi Province of China (GJJ150189).
© 2019 North Carolina State University.
- Hydrogen bond
- Ionic liquid
- NMR technique