Solvothermal-Based Lignin Fractionation From Corn Stover: Process Optimization and Product Characteristics.

Area of Science:

• Biomass Conversion
• Green Chemistry
• Materials Science

Background:

• Lignocellulosic biomass fractionation is crucial for producing biobased products.
• Efficient lignin extraction is key to unlocking its value.
• Corn stover is an abundant and underutilized lignocellulosic resource.

Purpose of the Study:

• To develop an efficient single-step solvothermal fractionation method for lignin extraction from corn stover.
• To optimize extraction conditions using response surface methodology (RSM).
• To characterize the recovered lignin and assess its structural integrity.

Main Methods:

• Single-step solvothermal fractionation using an ethyl acetate, ethanol, and water solvent mixture.
• Acid promotion with sulfuric acid (H2SO4) to enhance lignin removal and recovery.
• Optimization of temperature, time, and H2SO4 concentration using RSM.
• Characterization of extracted lignin using FTIR, TGA, elemental analysis, and 2D-HSQC NMR.

Main Results:

• Optimal conditions achieved 98.0% cellulose yield and 75.0% lignin removal with 72.9% lignin recovery.
• Recovered lignin primarily contains the β-O-4 linking motif.
• No significant formation of new C-C inter-unit linkages (β-β, β-5) in the recovered lignin.
• Characterization confirmed the structural integrity of the extracted lignin.

Conclusions:

• The developed method efficiently extracts high-purity lignin from corn stover in a single step.
• The recovered lignin retains its key structural features, making it suitable for valorization.
• This approach facilitates the conversion of corn stover into valuable chemicals and fuels.