Green oxidation of corn stover lignin as reinforcing plasticizer and UV-blocking agent for polyvinyl alcohol...

The high-value utilization of lignin is significantly constrained by its dark color and poor compatibility with polymer matrices. This study presents a green, H₂O₂-based alkaline oxidation process to transform corn stover enzymatic hydrolysis lignin into a functional additive for polyvinyl alcohol (PVA). Optimized via response surface methodology (RSM), the process yielded oxidized lignin (OL) that exhibited 59.3 % lower visible light absorbance (450 nm) and 146.5 % higher UV absorbance (335 nm) compared to raw lignin. Structural analysis revealed that oxidation significantly reduced lignin's molecular weight while increasing phenolic hydroxyl and carboxyl group content, markedly improving its compatibility and reinforcing plasticizer effect within PVA composites. Crucially, the OL was enriched with UV-absorbing p-coumaric acid and ferulic acid monomers. Resultant OL/PVA composite films demonstrated superior mechanical properties, high visible light transparency, and exceptional UV-blocking performance. Techno-economic analysis confirms the economic viability and sustainability of this green oxidation process, highlighting its potential to deliver significant economic benefits to biorefineries by upgrading a low-value byproduct. This work provides a novel, high-value pathway for lignin valorization as a multifunctional reinforcing plasticizer and UV-protective agent.