Lewis acid-mediated aqueous glycerol pretreatment of sugarcane bagasse: Pretreatment recycling, one-pot hydrolysis and lignin properties

Abstract Sugarcane bagasse was pretreated with lewis acid-mediated glycerol, results showed that 98.47% glucan recovery, 95.31% xylan removal and 49.69% delignification were achieved by pretreatment using 80 wt% aqueous glycerol combined with 1.0 wt% AlCl3 at 150 °C for 1 h. Reutilization experiments of acidified glycerol showed that its pretreatment efficiency was relatively well maintained during four consecutive cycles. Enzymatic in situ saccharification of pretreated bagasse led to about 50% glucose yield at 16 wt% glycerol concentration. After pretreatment, the lignin distributed in pretreatment hydrolysate and pretreated solid residue (referred to as organosolv lignin (OL) and cellulolytic enzyme lignin (CEL), respectively) demonstrated contrasting effect on enzymatic hydrolysis with OL slightly increasing while CEL decreasing cellulose conversion, which could be explained by their differences in hydrophobicity and surface charge. Further analysis of the structure and molecular weights of two lignin samples indicated their great potential for valorization into value-added products.