Elucidating adsorption behavior of cellulase on lignin through isolated lignin and model compounds

The hot water and green liquor pretreatments were conducted on Eucalyptus wood in the current study. The cellulase adsorption behavior on the isolated lignins and model compounds was clarified by a quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM). The QCM-D analysis indicated that the hot water pretreated lignin (HPL) adsorbed more cellulase than the green liquor pretreated lignin (GPL) and the protolignin (PL). The AFM analysis revealed that the interaction force between lignin and cellulase was in the order of HPL > GPL > PL which was consistent with the cellulase adsorption. The monomeric lignin model with the ketone group adsorbed more cellulase than the counterpart with the hydroxyl group or aldehyde group. The dimeric lignin models adsorbed more cellulase than the monomeric lignin models. Furthermore, the β – β dimer model adsorbed more cellulase than the β–5 and 5–5′ dimer models. This study provides fundamental knowledge for developing more efficient pretreatment technologies.