Improvement of the enzymatic hydrolysis of furfural residues by pretreatment with combined green liquor and hydrogen peroxide

A potential commercial pretreatment for furfural residues (FRs) was investigated by using a combination of green liquor and hydrogen peroxide (GL–H2O2). The results showed that 56.2% of lignin removal was achieved when the sample was treated with 0.6 g H2O2/g-DS (dry substrate) and 6 mL GL/g-DS at 80 °C for 3 h. After 96 h hydrolysis with 18 FPU/g-cellulose for cellulase, 27 CBU/g-cellulose for β-glucosidase, the glucose yield increased from 71.2% to 83.6%. Ethylenediaminetetraacetic acid was used to reduce the degradation of H2O2, the glucose yield increased to 90.4% after the addition of 1% (w/w). The untreated FRs could bind more easily to cellulase than pretreated FRs could. The structural changes on the surface of sample were characterized by X-ray photoelectron spectroscopy. The results indicated that the surface lignin could be effectively removed during pretreatment, thereby decreasing the enzyme–lignin binding activity. Moreover, the carbonyl from lignin plays an important role in cellulase binding.