Effect of reactive oxygen species on biomass structure in different oxidative processes

•Different radical species were utilized for lignocellulose degradation.•Superoxide radical anion modified biomass by C-C linkages cleavage of lignin.•Sulfate and hydroxyl radical oxidized the side chain of lignin.•Radical species degraded lignin selectively and led to weighty sugar yield.•O2− plays a more important role in biomass degradation than SO42−, HO2−, and HO.