Mild and efficient approach to aromatic backbone cleavage using copper-lignosulfonate/hydrogen peroxide system

This study investigates the dual role of copper ions in catalysis and complexation during the oxidation of lignosulfonates with hydrogen peroxide (H2O2) under alkaline conditions. The presence of copper ions reduces partial oxidation by 86 % compared to H2O2 treatment alone, enhancing overall conversion efficiency to 63 % under increased oxidative conditions. Analyses reveal that copper-lignosulfonate complexes facilitate redox cycling and hydroxyl radical generation through interactions with H2O2, confirming copper's dual functions. This mechanism mitigates the hindrance of sulfonic groups on hydroperoxide anions, leading to lignosulfonate degradation into dicarboxylic acids. These findings provide novel insights into the copper-lignosulfonate/H2O2 system, expanding the understanding of oxidative degradation mechanisms beyond traditional Fenton-like reactions. Furthermore, this system offers a simplified and efficient alternative for industrial applications, particularly in integration with the sulfite pretreatment process of woody biomass for producing valuable co- products.