Comparison of organosolv and hydrotropic pretreatments of eucalyptus for enhancing enzymatic saccharification

The objective of this study was to investigate the effects of organosolv and hydrotropic pretreatments on improving enzymatic hydrolysis of eucalyptus. The chemical composition of the fiber surface was analyzed using X-ray photoelectron spectroscopy (XPS) to determine the surface characteristics of pretreated eucalyptus. Other than the significant decrease of surface coverage by lignin, hydrotropic pretreatment was more effective in removing the lignin and xylose from fiber cell walls than organosolv pretreatment. The restriction of acetyl and phenolic groups in pretreated substrates was typically eliminated by hydrotropic pretreatments. Moreover, fiber structure and morphology after pretreatments were more suitable for enzymatic hydrolysis. Cellulase adsorption capacity was notably improved by hydrotropic pretreatment, which indicating the better enzyme accessibility of cellulose in pretreated substrates. Eventually, higher glucose yield was obtained with hydrotropic pretreatment. In addition, the precipitated lignin as an important by-product of pretreatments was characterized by Fourier transforms infrared spectroscopy (FTIR) also.