Enhanced Antioxidant Capacity of Miscanthus-Derived Lignins via Organosolv Process Variation and Autohydrolysis

This study examines the impact of autohydrolysis (AH) and ethanol-based organosolv pulping on the structure and antioxidant properties of lignins derived from Miscanthus × giganteus. Lignin is a complex aromatic biopolymer with significant potential as sustainable resource for advanced materials and antioxidants. Structural modifications were assessed using sophisticated analytical techniques, including 2D nuclear magnetic resonance spectroscopy and headspace-gas chromatography-mass spectrometry, complemented by functional assays evaluating antioxidant capacity. AH at 180 °C leds to a notable increase in phenolic hydroxyl groups through ether bond cleavage and stabilization of methoxy functionalities, enhancing antioxidant performance. Moreover, organosolv pulping introduced ethoxy groups, increasing structural complexity and functionality. These modifications significantly improve free-radical scavenging capacity, highlighting lignin's potential as an antioxidant additive in biobased polymers and coatings. The study emphasizes the role of AH temperature in optimizing lignin functionality and presents a strategy to enhance its utility as a versatile biobased industrial material.