Direct extraction of polysaccharides from moso bamboo (<em>Phylostachys heterocycla</em>) chips using a mixed solvent system of an amino acid ionic liquid with polar aprotic solvent

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>The cellulose-dissolving ability and some physical properties of mixed solvents of an amino acid IL, <em>N</em>-methyl-<em>N</em>-(2-methoxyethyl)pyrolidin-1-ium 2,6-diaminohexanoate ([P_1ME][Lys]), with polar aprotic solvents, such as 1,3-dimethylimidazolidinone (DMI), <em>N</em>,<em>N</em>-dimethylformamide (DMF), dimethylsulfoxide (DMSO), and acetonitrile (CH₃CN), have been investigated. The viscosity was significantly reduced by the increasing content of polar aprotic solvents, and a 1:1 mixture (molar ratio) of [P_1ME][Lys] with DMF showed 91.5 cP which corresponded to less than 1/10 compared to that of the pure IL at 25 °C (1058 cP). The β values of the mixed solvents, which have the IL contents over 0.1, exhibited β-values similar to that of the pure IL. On the other hand, the π-value was dependent on the ratio of the IL content, and the pure IL had the highest π-value. We found that the mixed solvent of [P_1ME][Lys] with DMF (1:1) easily dissolved the cellulose and the mixed solvent could be used to extract cellulose from moso bamboo (<em>Phylostachys heterocycla</em>) powder. The efficiency of the extraction of cellulose from the bamboo powder was significantly increased when a 1:1 mixture of the IL with a polar aprotic solvent was used as the extracting solvent at 60 °C; the extraction ratio of the 1:1 mixture (IL: DMF) reached twice that of the pure IL. We thus obtained cellulose in 18% (w/w) yield from the bamboo powder.</p></div>