Li Debao, Qi Letian, Gibril Magdi E, Xue Yu, Yang Guihua, Yang Mengru, Gu Yujie, Chen Jiachuan
State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.
Faculty of Industries Engineering and Technology, University of Gezira, Wad Medani 2667, Sudan.
Polymers (Basel). 2024 Dec 20;16(24):3560. doi: 10.3390/polym16243560.
Lignin, the most abundant natural aromatic polymer, holds considerable promise for applications in various industries. The primary obstacle to the valorization of lignin into useful materials is its low molecular weight and diminished chemical reactivity, attributable to its intricate structure. This study aimed to treat lignocellulosic biomass using a switchable solvent (DBU-HexOH/HO) derived from the non-nucleophilic superbase 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU), which efficiently separates and extracts lignin from poplar wood. Additionally, it sought to characterize fundamental properties of the extracted switchable solvent lignin (SSL) and propose a mechanism for its separation. In comparison to milled wood lignin, SSL exhibits a greater molecular weight, superior homogeneity, and enhanced stability. The SSL sample was analyzed using spectroscopies including infrared spectroscopy, nuclear magnetic resonance, and X-ray photoelectron spectroscopy. The findings indicated that the structure of SSL was preserved, with the switchable solvent primarily cleaving the C-C and α-O-4 bonds, resulting in a low hydroxyl content, an elevated H/C ratio, and a reduced O/C ratio. The SSL was successfully prepared to lignin nanoparticles (LNPs) with size range of 531-955 nm. This paper presents a technique for processing lignocellulosic biomass using a switchable solvent, highlighting advancements in lignin's structure and enhancing its use in the chemical sector.
木质素是最丰富的天然芳香族聚合物，在各个行业的应用中具有巨大潜力。将木质素转化为有用材料的主要障碍是其分子量低且化学反应性降低，这归因于其复杂的结构。本研究旨在使用由非亲核超强碱1,8 - 二氮杂双环[5.4.0]十一碳 - 7 - 烯（DBU）衍生的可切换溶剂（DBU - HexOH/HO）处理木质纤维素生物质，该溶剂能有效从杨木中分离和提取木质素。此外，研究试图表征提取的可切换溶剂木质素（SSL）的基本性质，并提出其分离机制。与磨木木素相比，SSL具有更高的分子量、更好的均匀性和更高的稳定性。使用红外光谱、核磁共振和X射线光电子能谱等光谱学方法对SSL样品进行了分析。结果表明，SSL的结构得以保留，可切换溶剂主要切断C - C键和α - O - 4键，导致羟基含量低、H/C比升高和O/C比降低。成功制备了尺寸范围为531 - 955 nm的木质素纳米颗粒（LNP）。本文介绍了一种使用可切换溶剂处理木质纤维素生物质的技术，突出了木质素结构方面的进展，并增强了其在化学领域的应用。
