Abstract

The concept of wood biorefinery is envisioned as the selective separation of the three main wood components, cellulose, hemicellulose and lignin, and the subsequent utilization of each fraction for production of fuels, high value-added chemicals and other related products. The hemicelluloses can be previously disassembled from the wood matrix before pulping, using various physical-chemical processes such as autohydrolysis, steam explosion, acid hydrolysis or alkaline extraction. In this work, two treatments, diluted acid (combined severity factor = 1.26 to 1.82) and saturated vapor (severity factor, Ro = 3.64 to 4.23) were used to the removal of hemicelluloses from P. radiata wood chips. Results showed that the content of solids decreased with the increase in severity. As a consequence, more hemicelluloses, and also lignin, were dissolved in the soluble fraction. The content of hemicelluloses in liquid fraction varied between 41-53% and 26-61% in diluted acid and saturated vapor, respectively (in original hemicelluloses basis). Yield of solids in dilute acid extraction varied between 76-91%, while in the saturated vapor extraction it varied between 67-81%. FT-MIR spectrum of extracted wood showed an increase in the intensity at 1607 cm-1, corresponding to lignin for both extraction methods. Absorbance at 1430 cm-1 indicates an increase in the content of crystalline cellulose. Scanning electron microscopy (SEM) of extracted wood showed a collapse of the fiber surface with increasing the extraction severity, especially with saturated vapor extraction. New experiments are being performed in order to fully characterize the fractions and determined their possible uses as bioethanol, paper strength additives, dissolving pulp, hydrogels, among others.