Ultra-high-pressure homogenization combined with ionic liquid-organic acid solvent for effective pretreatment of lignocellulose biomass

The complex structure of lignocellulose necessitates advanced pretreatment techniques to effectively separate its three primary components for further conversion into valuable products. This study introduced an innovative approach to pretreating bagasse by commencing with ultra-high-pressure homogenization (UHPH) applied to raw bagasse, which maintained chemical integrity while reducing intermolecular bonds, crystallinity, and particle size. Subsequently, UHPH-bagasse underwent pretreatment using a synergistic solution of ionic liquid ([Bmim]Cl) and organic acid (oxalic acid: OA). This combination achieved a remarkable 90.26 % lignin removal rate, surpassing many conventional methods. The influence of temperature on pretreatment efficiency was also explored, demonstrating effective lignin removal at temperatures below 130 °C without compromising cellulose integrity. This performance greatly enhanced cellulose conversion into levulinic acid (from 38.8 % to 57.5). However, temperatures exceeding 140 °C led to lignin depolymerization and subsequent re-aggregation on the residue's surface, hindering cellulose conversion. The [Bmim]Cl-OA system not only aided bagasse delignification but also promoted cleavage of β-O-4' linkages, especially at higher temperatures. The resulting lignin exhibited reduced molecular weight and nanoscale particle size, enhancing its antioxidant properties and suggesting potential applications in lignin-based chemicals and materials.