Structural and physicochemical characterization of hemicelluloses isolated by alkaline peroxide from barley straw |
| |
| Authors: | RunCang Sun X F Sun G Q Liu P Fowler J Tomkinson |
| |
| Affiliation: | 1. Centre for Straw and Wood Utilization, The North-Western Sciences and Technology University of Agriculture and Forestry, Yangling, People's Republic of China;2. The BioComposites Centre, University of Wales, Bangor, UK |
| |
| Abstract: | Seven hemicellulosic preparations were obtained from barley straw by extraction with 1.5% H2O2 at pH 12.0 for 14 h at 45 °C with extractant to straw ratios of 10:1, 13:1, 15:1, 18:1, 20:1, 25:1 and 30:1. The respective yields of dissolved hemicelluloses were 28.4 wt%, 28.8 wt%, 29.7 wt%, 30.1 wt%, 30.6 wt%, 30.8 wt% and 30.8 wt% or dry barley straw, corresponding to release of 78.7%, 79.8%, 82.3%, 83.4%, 84.8%, 85.3% and 85.3% of the original hemicelluloses. The polymers were mainly composed of xylose, arabinose, glucose, galactose and 4-O-methyl-D -glucuronic acid (59.3–62.6%, 19.7–22.0%, 8.8–12.5%, 5.6–6.9% and 5.8–6.7%, respectively) and had weight-average molecular weights of between 38 470 and 41 050 g mol−1.13 CNMR spectroscopy confirmed the results obtained by chemical methods, and showed that the hemicellulosic fraction was mostly by L -arabino-(4-O-methyl-D -glucurono)-D -xylan. More importantly, it was found that lignin provides some protection for the hemicelluloses in barley straw against attack by hydrogen peroxide. © 2002 Society of Chemical Industry |
| |
| Keywords: | hemicelluloses barley straw hydrogen peroxide lignin FTIR 13C NMR |
|
|
