Synergistic antioxidant performance of lignin extracted with deep eutectic solvent from olive mill solid waste in...

Lignin is known to exhibit synergistic antioxidant effects when used together with small molecule antioxidants. However, whether similar effects occur in polymer blends containing lignin as the only antioxidant component remains largely unexplored. This study investigates the synergistic antioxidant effects of lignin derived from olive mill solid waste (OL) when incorporated as the sole active component in polyvinyl alcohol (PVA) polymer blends. PVA films and electrospun fibers containing 0-11 wt% OL showed antioxidant activity exceeding rule-of-mixtures predictions. The maximum synergy occurred at 4 wt% OL, with enhancements of 480% for films and 971% for fibers, compared to 33% for sodium lignosulfonate. Spectroscopic and thermal analyses revealed that this synergy stems from morphology-dependent intermolecular interactions. These findings represent one of the strongest synergistic antioxidant effects reported for a lignin/polymer system, presenting a sustainable pathway to convert agricultural waste into high-performance materials for active packaging and other advanced applications.