Production of nanocellulose using acidic deep eutectic solvents based on choline chloride and carboxylic acids: A review

Nowadays, nanocellulose production processes with numerous merits of green, eco-friendly, and cost-effective are in urgent need. Acidic deep eutectic solvent (ADES), as an emerging green solvent, has been widely applied in the preparation of nanocellulose over the past few years, owing to its unique advantages, including non-toxicity, low cost, easy synthesis, recyclability, and biodegradability. At present, several studies have explored the effectiveness of ADESs in nanocellulose production, particularly those based on choline chloride (ChCl) and carboxylic acids. Various acidic deep eutectic solvents have been employed, with representative ones such as ChCl-oxalic/lactic/formic/acetic/citric/maleic/levulinic/tartaric acid. Herein, we comprehensively reviewed the latest progress of these ADESs, focusing on the treatment procedures and key superiorities. In addition, the challenges and outlooks of ChCl/carboxylic acids-based DESs implementation in the fabrication of nanocellulose were discussed. Finally, some suggestions were proposed to advance the industrialization of nanocellulose, which would help for the roadmap of sustainable and large-scale production of nanocellulose.

Automated summary

Nowadays, there is an urgent need for nanocellulose production processes that are green, eco-friendly, and cost-effective. Acidic deep eutectic solvents (ADES) have been widely used in the preparation of nanocellulose due to their unique advantages. Several studies have explored the effectiveness of ADESs, particularly those based on choline chloride (ChCl) and carboxylic acids. This review comprehensively summarizes the latest progress of these ADESs and discusses the challenges and outlooks of implementing ChCl/carboxylic acids-based DESs in nanocellulose fabrication.