Abstract

The ionoSolv pretreatment generates a cellulose pulp by extracting hemicellulose and lignin using low-cost ionic liquids. In this study, cellulose pulp was obtained from Miscanthus × giganteus using the protic ionic liquid triethylammonium hydrogen sulfate [N₂₂₂₀][HSO₄] with 20% water as a co-solvent and characterised in detail for its material properties as a function of pretreatment severity. We measured the particle size distribution, porosity and crystallinity of the unbleached pulps and the molar weight distribution of the cellulose contained within. We report that the surface area increased and the size of the pulp particles decreased as ionoSolv processing progressed. While the native cellulose I structure was maintained, the average degree of polymerisation of the cellulose was reduced to a DP_n of around 300, showing the cellulose polymers are shortened. We correlate the pulp properties with enzymatic saccharification yields, concluding that enzymatic saccharification of the cellulose after ionoSolv pretreatment is mainly enhanced by removing hemicellulose and lignin. We also observed that overtreatment deteriorated saccharification yield and that this coincides with cellulose fibrils becoming coated with pseudolignin redeposited from the ionic liquid solution, as demonstrated by FT-IR spectroscopy. Pseudolignin deposition increases the apparent lignin content, which is likely to increase chemical demand in bleaching, suggesting that both glucose release and material use benefit from a minimum lignin content. Overall, this study demonstrates that cellulose pulps isolated with ionoSolv processing are not only a promising intermediate for high-yield release of purified glucose for biorefining, but also have attractive properties for materials applications that require cellulose I fibrils.

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摘要

ionoSolv预处理通过使用低成本离子液体提取半纤维素和木质素来生成纤维素纸浆。在这项研究中，从获得的纤维素纸浆芒草×巨使用质子型离子液体三乙基硫酸氢[N ₂₂₂₀ ] [HSO ₄用20％的水作为助溶剂，并详细表征其材料性质与预处理强度的关系。我们测量了未漂白纸浆的粒度分布，孔隙率和结晶度以及其中所含纤维素的摩尔质量分布。我们报告说，随着ionoSolv处理的进行，表面积增加，纸浆颗粒的尺寸减小。在保持天然纤维素I结构的同时，纤维素的平均聚合度降低至DP _n大约300，表明纤维素聚合物缩短了。我们将果肉特性与酶促糖化产率相关联，得出结论，离子水预处理后纤维素的酶促糖化作用主要是通过去除半纤维素和木质素来增强的。我们还观察到，过度处理会降低糖化收率，这与纤维素原纤维被离子液体溶液中再沉积的假木质素包被相吻合，这是通过FT-IR光谱学证实的。假性木质素的沉积增加了表观木质素含量，这很可能增加了漂白过程中的化学需求，这表明葡萄糖的释放和原料的使用都受益于最低的木质素含量。总体，

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