Efficient Separation of Poplar Lignin Using a New Carboxylic Acid‐Based Deep Eutectic Solvents – Choline Chloride/Malonic Acid
Xing Long, Mingzhu Yao, Shaoyan Wang, Chuangqi Ren, Xiao Zhao, Chengrong Qin, Liang Chen, Caoxing Huang, Shuangquan Yao
Abstract
Abstract Separation of lignin by pretreatment is an important step in biomass refining. This study investigated how a novel dicarboxylic acid‐based deep eutectic solvent (DES) – choline chloride (ChCl)/malonic acid (MA) – affected the process of separating lignin from poplar. At 140 °C for 3.0 h, with a ChCl: MA molar ratio of 1: 3.5, the ideal pretreatment conditions were met, and 91.8 % lignin was obtained. Even after five DES reuses, the consistent and effective separation efficiency of 77.9 % remains unchanged. The hydrolysate contained 92.4 % of the recovered lignin, with a purity of 94.6 %. Moreover, the regenerated lignin obtained through the new DES pretreatment exhibited a high phenolic hydroxyl content of 1.9 mmol g −1 and a low polydispersity index of 1.4. The results showed efficient and selective separation of lignin using the new binary carboxylic acid‐based DES pretreatment was achieved. This research offers a novel approach to effectively separate wood fiber biomass and extract valuable lignin.