Abstract The processing of lignocellulosic materials is very limited because of their low solubility in water and some organic solvents. Fifteen ternary deep eutectic solvents (DESs) were prepared and tested as solvents suitable for delignification of unbleached pulp. The selected ternary DESs are composed of quaternary ammonium salts and amino acids as hydrogen-bond acceptors, and organic acids and polyvalent alcohols as hydrogen bond donors, with molar ratios varying for the individual components. The delignification efficiency is significantly influenced by the degree of penetration of the solvent into the pulp fibre structure. Therefore, the density and viscosity analysis of individual solvents was performed. Unbleached beech pulp with initial kappa number 13.9 was treated with the prepared DESs. The kappa number indicates the residual lignin content or the bleachability of pulp. The efficiency of the solvents ranged from 1.4% to 28.1%. The most suitable for the pretreatment of fibres, based on lignin removal efficiency, were found to be three DESs, in the following order: malonic acid/choline chloride/1,3-propanediol (1:1:3) > choline chloride/acetamide/lactic acid (1:2:3) > choline chloride/urea/lactic acid (1:2:3).

中文翻译：

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三元低共熔溶剂对未漂白纸浆的脱木质素

摘要 木质纤维素材料在水和一些有机溶剂中的溶解度很低，因此其加工受到很大限制。制备并测试了 15 种三元低共熔溶剂 (DES) 作为适用于未漂白纸浆脱木素的溶剂。选择的三元DES由季铵盐和氨基酸作为氢键受体，有机酸和多元醇作为氢键供体组成，各个组分的摩尔比不同。溶剂渗透到纸浆纤维结构中的程度显着影响脱木素效率。因此，进行了各种溶剂的密度和粘度分析。用制备的 DES 处理初始 kappa 值为 13.9 的未漂白山毛榉浆。卡伯值表示残留木质素含量或纸浆的可漂白性。溶剂的效率范围为 1.4% 至 28.1%。根据木质素去除效率，发现最适合纤维预处理的是三种 DES，顺序如下：丙二酸/氯化胆碱/1,3-丙二醇 (1:1:3) > 氯化胆碱/乙酰胺/乳酸（1：2：3）>氯化胆碱/尿素/乳酸（1：2：3）。