Fractionating softwood lignocellulose using APW system for enhanced enzymatic hydrolysis

The pretreatment effects of acetone/phenoxyethanol/water (APW) system on three common softwoods (Chinese fir, cypress, and Pinus massoniana) were investigated in this study. Under 125 degrees C for 150 min, more than 80% of lignin and nearly 100% of hemicellulose were removed from these softwoods without coupling with other pretreatment methods. Moreover, the enzymatic hydrolysis efficiency of these wet residues was more than 88%. The characterization of the residue revealed that the APW system could effectively destroy the structure of lignocellulose and expose the cellulose to the surface, which enhanced enzymatic hydrolysis. Furthermore, the beta-O-4, beta-5, and beta-beta linkages between the lignin were destroyed, and the condensation structure appeared between G(2) and G(5) units. The Mw and Mn of lignin were reduced to 5642 and 1293 g/mol, and lignin with well pyrolysis activity was achieved. This study provides a potentially effective way to fractionate softwoods for biorefinery.