Oxidative Bagasse Fractionation for Its Efficient Utilization Based on a Lignin-First Approach.

Abstract

In order to tackle the challenges of biological refining, including strong acids/alkalis and high temperatures, the aerobic oxidation was implemented in the pretreatment of biomass for one-pot extraction and separation of lignin and carbohydrates by combining the processes of biomass hydrolytic fractionation and in situ lignin oxidative modification. As expected, the yields of oxidized lignin and carbohydrate residue under optimized pretreatment condition are up to 17.1% and 59.9%, respectively, and the oxidized lignin exhibits improved depolymerization performance, giving the phenolic monomer yield of around 245.0 mg g-1, which are higher than those of Kraft lignin (26.3 mg g-1) and sodium lignosulfonate (44.0 mg g-1) under identical conditions. Intensive investigation showed that this enhanced depolymerization performance is contributed to the existence of large number of aryl α-ketone functional groups in oxidized lignin obtained from the oxidation of β-O-4, β-5, and β-β linkages, reducing the activation energy of C-O interlinkages. Besides, the carbon material derived from carbohydrate calcination exhibits graphene-like structure and hierarchical porous architecture with micro-, meso-, and macro-pores. It is thus believed that the lignin-first process can significantly demonstrate unprecedented potential to accomplish the utilization of whole biomass components.