Abstract

Hemicelluloses from Pinus radiata wood chips were extracted using different conditions of temperature, time and initial pH of water (120 to 170 degrees C, 30 to 120 min and pH 2 to 12, respectively). Results showed that hemicelluloses represented 26% of wood dry weight and, from this amount, hexoses are responsible for 64% of its composition. The analysis of extraction results showed that pH has a low effect in disassembling hemicelluloses from wood, and that time and temperature of reaction were the most important parameters. Maximal amount of hemicellulose extracted in the most severe conditions tested was between 12-16% (on wood basis). In these conditions approximately 40-50% of the hemicellulose in wood was solubilized. As observed by SEC analysis, the recovered hemicellulosic fractions were in the form of low molar mass oligomers with Mw varying from 3720 to 54300 g/mol. The FT-IR spectra show peak multiplicity between 1120 and 1000 cm(-1) that is a typical characteristic of carbohydrates and only alkaline-extracted hemicelluloses showed the presence of lignin with a characteristic peak at 1509 cm(-1).