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Pretreatment of Eucalyptus urophylla in γ-valerolactone/dilute acid system for removal of non-cellulosic components and acceleration of enzymatic hydrolysis

Sun, Shao Ni, Chen, Xue, Tao, Ying Hua, Cao, Xue Fei, Li, Ming Fei, Wen, Jia Long, Nie, Shuang Xi, Sun, Run Cang
Industrial crops and products 2019 v.132 pp. 21-28
Eucalyptus urophylla, biomass, cell walls, cellulose, chemical composition, crystal structure, enzymatic hydrolysis, feedstocks, glucose, hemicellulose, lignin, molecular weight, sulfuric acid, value added
Enzymatic hydrolysis of biomass is highly dependent on the changes in chemical compositions and structural characteristics after pretreatment. γ-Valerolactone (GVL)/dilute acid pretreatment is an effective approach to remove hemicelluloses and lignin and disrupt the cell wall structure, leading to the improvement of enzymatic hydrolysis. This study examined the influence of chemical compositions and structural features on the enzymatic hydrolysis of Eucalyptus urophylla from GVL/dilute acid pretreatment. Results revealed that glucose yield showed a positive correlation with removal rate of hemicelluloses and lignin. Particularly, there was no direct correlation of cellulose crystallinity on enzymatic hydrolysis. The highest glucose yield of 89.1% was achieved when the pretreatment was performed with GVL/H2O solution (4:1, v/v) containing 100 mM H2SO4 at 120 °C for 60 min. Meanwhile, under the mentioned conditions, 16.5% of lignin with a high purity (only contained 0.09% sugars) and molecular weight (3450 g/mol) was fractionated, which can be served as feedstock for future utilization. In short, an extensive understanding of the pretreated biomass and the obtained lignin during the GVL/dilute acid pretreatment will be beneficial for value-added applications of biomass.