Upgrading lignin macromolecular by green and recyclable ternary deep eutectic solvents

Area of Science:

• Biomass Valorization
• Green Chemistry
• Macromolecular Science

Background:

• Lignin, a major aromatic biopolymer, faces utilization challenges due to complex structures and purification difficulties.
• Developing efficient pretreatment methods is crucial for unlocking lignin's high-value applications.

Purpose of the Study:

• To develop and investigate a microwave-assisted ternary deep eutectic solvent (DES) for effective lignin pretreatment.
• To analyze the impact of DES pretreatment on key lignin characteristics and understand the dissolution mechanism.

Main Methods:

• A ternary deep eutectic solvent (DES) composed of formic acid, lactic acid, and choline chloride was synthesized.
• Microwave irradiation was employed for lignin pretreatment using the developed DES.
• Characterization of regenerated lignin included purity, molecular weight, dispersity, thermal stability, phenolic hydroxyl content, and antioxidative activity analysis.

Main Results:

• Microwave-assisted ternary DES pretreatment significantly improved regenerated lignin purity.
• The process reduced lignin molecular weight and dispersity, indicating depolymerization.
• Enhanced thermal stability, higher phenolic hydroxyl content, and increased antioxidative activity were observed in the pretreated lignin.

Conclusions:

• The developed microwave-assisted ternary DES is an effective method for lignin pretreatment.
• This approach facilitates the regulation and upgrading of lignin macromolecules for potential high-value applications.