Effect of Condensate Obtained from Hydrothermal Pretreatment of Biomass on Pretreatment and Enzymatic Hydrolysis

In this study, the enzymatic hydrolysis efficiency of hydrothermal, condensate, and condensate/ball-milling (BM) pretreatments were evaluated using oak, miscanthus, and sweet sorghum bagasse, and the enzyme adsorption behavior was investigated. The hemicellulose was mainly degraded during condensate pretreatment compared with hydrothermal pretreatment (HT), resulting in a high degradation rate (14.77%–30.37%) of biomass, and a low content of hemicellulose in the pretreated biomass (11.56%–14.58%). The hemicellulose degradation components were mainly detected in the hydrolysate, and the content of degradation products in the hydrolysate was higher compared to the HT. As a result of the BM following the condensate pretreatment, all biomass exhibited decreased crystallinity. Compared to the other pretreatment conditions, the condensate/BM led to the highest enzymatic hydrolysis efficiency (96.57%–99.07%). The Langmuir isotherm model was found to suitable representing the enzyme adsorption behavior, describing the single-layer adsorption of enzymes on the biomass surface.