Li Penghui, Zhang Zihui, Zhang Xiaoxue, Li Kongyan, Jin Yongcan, Wu Wenjuan
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University Nanjing 210037 China
College of Light Industry and Food Engineering, Nanjing Forestry University Nanjing 210037 China.
RSC Adv. 2023 Jan 24;13(5):3241-3254. doi: 10.1039/d2ra06033g. eCollection 2023 Jan 18.
Lignocellulosic biomass raw materials are renewable resources with abundant reserves in nature, and have many advantages, such as being green, biodegradable and cheap. Lignin, one of the three significant components of lignocellulose, possesses a chemical structure rich in phenylpropane and is a primary aromatic resource for the bio-based economy. For the extraction and degradation of lignin, the most common method is the pretreatment of lignocellulose with deep eutectic solvents (DES), which have similar physicochemical properties to ionic liquids (ILs) but address the disadvantages associated with ILs (DES have the advantages of low cost, low toxicity, and non-flammability). In lignocellulose pretreatment, a large amount of solvent is generally required to achieve the desired effect. However, after treatment, a substantial volume of solvent will be wasted, and thus, the problem of the recovery and reuse of DES solution needs to be adequately solved. The methods and mechanisms of perfect DES regeneration will be discussed from the perspective of the elemental composition and features of DESs in this review, which will also outline the present DES recovery methods, such as rotary evaporation, membrane separation, freeze-drying, electrodialysis, The detailed process and the advantages and disadvantages of each method since 2018 are introduced in detail. Future DES recovery methods have been prospected, and the optimization of the functional properties of DESs after recovery is discussed. It is expected to find a convenient and efficient application method for DES extraction or degradation of lignin with low energy and low cost.
木质纤维素生物质原料是自然界中储量丰富的可再生资源，具有绿色、可生物降解和廉价等诸多优点。木质素是木质纤维素的三大重要成分之一，具有富含苯丙烷的化学结构，是生物基经济的主要芳香族资源。对于木质素的提取和降解，最常见的方法是用深共熔溶剂（DES）对木质纤维素进行预处理，DES的物理化学性质与离子液体（ILs）相似，但克服了ILs的缺点（DES具有成本低、毒性低和不可燃的优点）。在木质纤维素预处理中，通常需要大量溶剂才能达到预期效果。然而，处理后会浪费大量溶剂，因此，DES溶液的回收和再利用问题需要得到充分解决。本文将从DES的元素组成和特性角度探讨DES完美再生的方法和机制，还将概述目前的DES回收方法，如旋转蒸发、膜分离、冷冻干燥、电渗析等。详细介绍了自2018年以来每种方法的具体过程以及优缺点。展望了未来DES的回收方法，并讨论了回收后DES功能特性的优化。期望找到一种低能耗、低成本的便捷高效的应用方法，用于DES提取或降解木质素。
