Effect of pretreatment conditions for enzymatic hydrolysis residues using bark-containing biomasses

Lignocellulosic biomass has been widely recognized as renewable and sustainable resource and an alternative of fossil fuel through production of biofuel. For producing biofuel, lignocellulosic biomass was usually debarked because bark has relatively low amount of cellulose and high amount of lignin. Thus the utilization of bark-containing biomasses had benefits not only reduction of energy consumption by debarking process but also give a possibility to use more residues which a portion of the rest after enzymatic hydrolysis that corresponded with a concept of biorefinery. In biorefinery concept, lignocellulosic biomass was utilized for production of bioethanol as well as biochemical using lignin. The objective of this study was to characterize residues, byproducts of enzymatic hydrolysis through various pretreatment methods, and also determine pretreatment condition which produce high yield of pentose and glucose.

Dilute acid pretreatment, organosolv pretreatment and autohydrolysis were conducted using powders of bark-containing Larix kaempferi and Quercus mongolica, and these pretreatment methods generally facilitated the removal of hemicellulose. The pretreatment process was operated at 160 to 180°C and the reaction times were 30 to 60 minutes. 1% of sulfuric acid was used as an acidic catalyst under dilute acid and organosolv pretreatments. After pretreatment, solid residues were separated from liquid hydrolysate and conducted enzymatic hydrolysis for producing glucose. The yields of residues after enzymatic hydrolysis were determined and chemical characterization was evaluated by GPC and NBO. Liquid hydrolysate was also analyzed by HPLC.