Green solvent-based processing of sugarcane bagasse and agricultural residues: Towards integrated lignocellulosic biorefineries

• Deep eutectic solvents with ethanolamine and choline chloride as HBAs were studied. • These DESs effectively disrupted raw bagasse and removed lignin. • ChCl: acetic acid DES gave the highest saccharification yield of 97.6%. • Pretreatment improved cellulose accessibility and crystallinity index. • DESs offer a greener, safer alternative to conventional alkali methods. Efficient pretreatment of lignocellulosic biomass is critical to overcoming the structural recalcitrance of raw sugarcane bagasse and enhancing enzymatic saccharification to fermentable sugars. In this study, four deep eutectic solvents (DESs), composed of choline chloride (ChCl) or ethanolamine (Eth) with lactic acid (LA) or acetic acid (AA), were systematically evaluated for their delignification efficiency and impact on glucose yields. Pretreatment conditions were optimized using a Plackett–Burman design, focusing on temperature, reaction time, and DES-to-solid ratio. Among the tested systems, ChCl:AA achieved the highest saccharification yield (∼98%) with low solid recovery (∼56%) and increased crystallinity (∼49%), demonstrating strong delignification and hemicellulose removal. Eth:AA also performed effectively, delivering ∼91% saccharification yield with moderate solid recovery (∼75%) and a crystallinity index of ∼31%, highlighting the potential of ethanolamine-based DESs as competitive alternatives to conventional choline chloride systems. In contrast, lactic acid-based DESs (ChCl:LA and Eth:LA) exhibited higher solid recoveries (>80%) but lower saccharification yields (65–82%), indicating milder pretreatment effects. Structural modifications were confirmed by SEM and FTIR analyses. These findings establish the relative efficiency of ethanolamine- and choline chloride-based DESs and demonstrate that acetic acid-based DESs, particularly ChCl:AA, enable efficient and green biomass pretreatment for improved sugar recovery from lignocellulosic residues.