The high viscosity of deep eutectic solvent (DES) limits its application in industrial production due to reduced mass transfer efficiency within the solvent system. Incorporating water into the solvent system can effectively reduce the viscosity of DES. In this study, DES based on glycerol and choline chloride were prepared, and the physicochemical properties of DES-water mixtures and the impact of various water contents in the solvent system on the pretreatment efficiency of poplar was investigated. At a 35% water content in the solvent system, the solvent's viscosity drops by 95%. The separation results from poplar experiments demonstrated that adding 10%−15% water to the solvent system promoted lignin dissolution and increased its extraction rate. Following pretreatment, the solid product cellulose exhibited a purity level exceeding 80%, with an enzymatic hydrolysis rate exceeding 95%. Structural characterization analysis revealed that the total phenolic hydroxyl content of lignin increased, along with an increase in cellulose crystallinity. Adding water to the solvent system improved both the purity of lignin and the content of active hydroxyl groups. Additionally, there was a more uniform distribution in molecular weight. This study comprehensively discussed the feasibility of using water as an auxiliary solvent for DES-based lignocellulose pretreatment. This approach is expected to facilitate industrialization and enhance preferential lignin extraction during pretreatment.

中文翻译：

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深度低共熔溶剂和水二元系统预处理木质纤维素以增强木质素提取和纤维素糖化

低共熔溶剂（DES）的高粘度由于溶剂体系内的传质效率降低而限制了其在工业生产中的应用。在溶剂体系中掺入水可以有效降低DES的粘度。本研究制备了基于甘油和氯化胆碱的DES，并研究了DES-水混合物的理化性质以及溶剂体系中不同含水量对杨树预处理效率的影响。当溶剂体系中的水含量为35%时，溶剂的粘度下降95%。杨树实验的分离结果表明，在溶剂体系中添加10%−15%的水促进了木质素的溶解并提高了其提取率。预处理后，固体产物纤维素的纯度超过80%，酶解率超过95%。结构表征分析表明，木质素的总酚羟基含量增加，纤维素结晶度增加。在溶剂体系中添加水可以提高木质素的纯度和活性羟基的含量。此外，分子量分布更均匀。本研究全面探讨了使用水作为辅助溶剂进行基于DES的木质纤维素预处理的可行性。该方法有望促进工业化并增强预处理过程中木质素的优先提取。