Dissolution of bamboo hemicellulose in 1-butyl-3-methylimidazolium halide-based ionic liquids

Abstract

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.

Atomic Level Interactions and Suprastructural Configuration of Plant Cell Wall Polymers in Dialkylimidazolium Ionic Liquids

“…Previous research has expounded on the significance of IL-anions in bringing about the dissolution of cellulose, 11 but such reports are lacking for xylan and lignin. In this current study, when comparing the absolute changes in chemical shifts of C11, the largest change was observed for ) of all IL carbon atoms in the presence of (A) 10% (w/w) birchwood xylan and (B) 10% (w/w) organosolv lignin, determined using 13 C NMR spectroscopy at 80 °C. xylan (Δδ ∼ 0.43 ppm), followed by cellulose (Δδ ∼ 0.24 ppm), and then lignin (Δδ ∼ 0.18 ppm).…”

“…In this study, 13 C NMR spectroscopy showed that cellulose, xylan, and lignin polymers interacted differently with select 1,3dialkylimidazolium ILs. Cellulose exhibited the strongest interactions with [EMIM][OAc], whereas xylan and lignin exhibited significantly higher interactions with [AMIM][OAc].…”

Ionic liquid depolymerize the lignocellulose for the enzymatic extraction of feruloylated oligosaccharide from corn bran

“…4 . The cationic acid C2-H proton of the imidazole carboxylate ILs forms hydrogen bonds with the ether and bridge oxygen atoms in the hemicellulosic molecules, and the carboxylate anion forms hydrogen bonds with OH protons in hemicelluloses ( Yuan et al, 2019 ). The effect of water in the pretreatment system is to reduce the viscosity of [Amim]OAc, improve the diffusion coefficient of [Amim]OAc in the pretreatment process, so as to enhance the diffusion performance.…”

Isopiestic Studies on Mixed Ionic Liquid Aqueous Solutions at 298.15 K

“…Therefore, imidazolium-based ionic liquids with the same cations and different anions, including [C 4 MIM]­Cl, [C 4 MIM]­Br, and [C 4 MIM]­I, were selected to investigate the effect of anion on isopiestic systems. The ionic liquid 1-alkyl-3-methylimidazolium halide can be used as a catalyst, electrolyte, and also to dissolve the biopolymers and as a solvent for some reactions …”

“…Therefore, imidazolium-based ionic liquids with the same cations and different anions, including [C 4 MIM]Cl, [C 4 MIM]Br, and [C 4 MIM]I, were selected to investigate the effect of anion on isopiestic systems. The ionic liquid 1-alkyl-3-methylimidazolium halide can be used as a catalyst, 35 electrolyte, 36 and also to dissolve the biopolymers 37 and as a solvent for some reactions. 35 In the next section, the ability of the equations derived from the linear isopiestic relation, LIR, to calculate the thermodynamic properties (density, sound velocity, and surface tension) of the ternary aqueous IL1 + IL2 solutions using the corresponding data of the sub-binary systems (IL1 + water and IL2 + water) in isopiestic equilibrium with the ternary system, was investigated.…”