Selective fractionation and enzymatic hydrolysis of Eucalyptus nitens wood

Abstract

Eucalyptus nitens, a fast growing species with remarkable resistance to plagues and ability to grow in frosting zones, was employed as a raw material for chemical fractionation following a selected biorefinery scheme. E. nitens wood samples were assayed for composition, and subjected to consecutive stages of hydrothermal processing (to solubilize the hemicellulosic fraction), organosolv delignification (for obtaining sulfur-free, soluble lignin fragments and a cellulose-enriched solid phase) and swelling. The various fractions from the processing stages were assayed for yield and composition. Operating under selected conditions, the hydrothermal stage allowed the recovery of 80.7% of the initial xylan as soluble hydrolysis or hydrolysis–dehydration products. The solid leaving the swelling stage contained 88.3% cellulose, and accumulated 90.2% of the cellulose present in the native wood. Near total cellulose conversion into glucose was achieved when the swelled solid was employed as a substrate in enzymatic hydrolysis experiments performed under selected operational conditions.