Modified Hydrothermal Pretreatment Conditions Enhance Alcohol Solubility of Lignin from Wheat Straw Biorefining

Lignin-rich residues from lignocellulosic biorefineries remain underutilized, limiting their economic viability. This study demonstrates how modifying hydrothermal pretreatments with temperatures and additives enhances the lignin-rich residue’s solubility in alcohol, a key step toward its valorization in biofuel and material applications. Effective carbohydrate removal greatly enhanced the residue’s alcohol solubility, supporting both saccharification and lignin utilization. Notably, a 5% hydrogen peroxide treatment doubled the residue’s alcohol solubility, reaching ~40%, while maintaining similar saccharification yields. Low concentrations of surfactants and oxidizers enhanced the alcohol solubility independently of the saccharification yield, while alkali improved both. These findings highlight that minor pretreatment adjustments, such as low-concentration additives, can optimize lignin’s utilization in biorefineries, while maintaining a high carbohydrate conversion