Efficient Separation of Poplar Lignin Using a New Carboxylic Acid‐Based Deep Eutectic Solvents – Choline Chloride/Malonic Acid

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.