Dingkai Wang, Mingyu Cui, Xutang Liu, Meiling Liu, Xiaopeng Han, Xiaoming Xiong, Shanglong Chen, Shangshang Ma, Qiqi Sun, Lingfeng Jiao, Wei Zhao
Lignin, a complex natural three-dimensional aromatic polymer, is prone to condensation during the separation process, owing to the diverse properties of its basic structural units, linkage types, and spatial configurations. These inherent structural complexities present significant challenges for its efficient isolation and precise transformation. Current separation techniques primarily include physical, chemical (such as acid hydrolysis, alkaline dissolution, organic solvents, and ionic liquids), and biological methods. Each approach offers distinct advantages and limitations in terms of yield, purity, cost, and impact on lignin structure. Studies have indicated that ionic liquids and organic solvent methods demonstrate considerable application potential owing to their mild reaction conditions and high selectivity. Future research should focus on developing green, efficient, and low-cost separation technologies, while also enhancing detailed structural characterization and targeted lignin conversion to facilitate its large-scale utilization in the production of value-added materials and chemicals.