Deep eutectic solvents (DESs) are widely used as recyclable green solvents for the separation of lignin from lignocellulosic biomass. However, the poor permeability of DES solution limits the green advancement of separation systems. In addition, lignin fragment molecules are susceptible to repolymerization reactions during separation, resulting in reduced lignin reactivity. In this study, a DES consisting of choline chloride (ChCl) as a hydrogen acceptor, 5-sulfosalicylic acid (5Saa) as a hydrogen donor, and a certain amount of γ-valerolactone (GVL) as an additive was designed. The system not only efficiently fractionated lignin from poplar (71.35%), but also selectively retained almost complete cellulose (retention 92.87%) under the optimal fractionation (ChCl/5Saa/GVL molar ratio 1/4/15, temperature 120 °C, time 3.0 h). Pre-crushing processing of raw materials was avoided as the new DES solution has stronger permeability compared to the previous DES solution. Selective deconstruction of lignocellulose was achieved due to a strong hydrogen network structure. The lignin fragments were effectively dissolved. The results showed that the stability of the carbo-positive active intermediates was enhanced by ChCl–5Saa/GVL. Lignin with a low molecular weight (2305 g mol⁻¹), high purity (98.77%) and high total phenolic hydroxyl content (6.92 mmol g⁻¹) was obtained. Homogeneous lignin nanoparticles (LNPs) were prepared with an average particle size of 23 nm. LNPs had high dispersion stability and excellent UV shielding properties. The green advancement of the new DES has been significantly improved and the efficient fractionation of high-value lignin was realized.

中文翻译：

---

使用含有γ-戊内酯的功能性低共熔溶剂有效提取木质素并修饰其分子结构制备均质木质素纳米颗粒

低共熔溶剂（DES）被广泛用作可回收的绿色溶剂，用于从木质纤维素生物质中分离木质素。然而，DES溶液的渗透性较差，限制了分离系统的绿色发展。此外，木质素片段分子在分离过程中容易发生再聚合反应，导致木质素反应性降低。本研究设计了一种由氯化胆碱（ChCl）作为氢受体、5-磺基水杨酸（5Saa）作为氢供体以及一定量的γ-戊内酯（GVL）作为添加剂组成的DES。该系统不仅能有效分馏杨木中的木质素（71.35%），而且在最佳分馏（ChCl/5Saa/GVL摩尔比1/4/15，温度120℃，时间）下选择性保留几乎完整的纤维素（保留92.87%） 3.0 小时）。由于新的DES溶液比以前的DES溶液具有更强的渗透性，因此避免了对原材料的预粉碎处理。由于强大的氢网络结构，实现了木质纤维素的选择性解构。木质素碎片被有效溶解。结果表明，ChCl–5Saa/GVL 增强了碳正活性中间体的稳定性。获得了低分子量（2305 g mol ^-1）、高纯度（98.77%）和高总酚羟基含量（6.92 mmol g ^{-1 ）的木质素。}制备平均粒径为 23 nm 的均质木质素纳米颗粒 (LNP)。LNPs具有高分散稳定性和优异的紫外线屏蔽性能。新型DES的绿色化程度显着提高，实现了高价值木质素的高效分馏。