通过100mL高压水热反应釜对小麦秸秆进行稀酸预处理高效制备可发酵糖。Condensed lignin produced during dilute acid pretreatment is the main cause of low cellulose conversion and high enzyme dosage. In this study, polyethylene glycol (PEG) assisted low-concentration p-toluenesulfonic acid (p-TsOH) pretreatment for reducing lignin condensation and enhancing enzymatic hydrolysis of wheat straw was investigated. In addition, the structure of lignin in wheat straw before and after pretreatment was systematically characterized. The results indicated that the cellulose conversion of pretreated wheat straw was significantly improved. Under the optimized conditions (0.5 % PEG6000 and 1 % p-TsOH), the cellulose conversion of pretreated wheat straw increased by 41.03 % and the enzyme loading decreased by 70 %. The cellulose conversion of pretreated wheat straw reached 95.15 % when the enzyme loading was only 7.5 mg/g (3.39 FPU/g). The lignin characterization revealed that the β-O-4 structure in lignin was protected by the PEG, which was incorporated into the β-O-4 structure and formed etherified lignin with many hydroxyl tails. Thus, the increase in cellulose conversion is attributed to the fact that the lignin condensation was inhibited by PEG, which reduced the non-productive adsorption of enzyme. p-TsOH and PEG showed significant synergistic effects for the improvement of cellulose conversion. In summary, PEG assisted low-concentration p-TsOH pretreatment can effectively prevent lignin condensation and improve enzymatic hydrolysis efficiency.
