Sustainable Valorization of Sugarcane Leaves by Using Surfactant-Assisted Deep Eutectic Solvent Pretreatment

Efficient pretreatment is crucial for maximizing sugar release from lignocellulosic biomass. In this study, sugarcane leaves were pretreated with a ternary deep eutectic solvent (DES) composed of choline chloride, ethylene glycol, and p-toluenesulfonic acid. This pretreatment significantly improved enzymatic hydrolysis compared to untreated biomass, increasing sugar yield from 0.14 to 0.31 g/g under optimized conditions (1:2:0.5 molar ratio, 120 °C, 20 min, S/L ratio 1:10). Further enhancement was achieved by soaking the biomass in PEG 4000 before DES pretreatment. Soaking sugarcane leaves in 5% PEG 4000 (w/w biomass) for 18 h produced the highest reducing sugar yield of 0.44 g/g. The improvement was attributed to reduced non-productive lignin binding to the enzyme and better enzyme accessibility to cellulose. The 3.14 times higher reducing sugar yield of presoaked biomass compared to untreated biomass demonstrates that combining PEG 4000 soaking with DES pretreatment provides a synergistic effect, offering a promising strategy for the efficient valorization of sugarcane leaves.