Physicochemical and thermal characterisation of residual hemicelluloses isolated by TAED activated peroxide from ultrasonic irradiated and alkali organosolv pre-treated wheat straw

Abstract

Eight white residual hemicellulosic preparations were obtained by post-treatment with TAED activated peroxide (2% H2O2–0.2% TAED at pH 11.8 for 12 h at 48 °C) from the ultrasonic irradiated and alkali organosolv pre-treated wheat straw. It was found that the post-treatment under the condition given released 44.5–53.5% of the original hemicelluloses and 14.8–30.8% of the original lignin. All the hemicelluloses extracted by TAED activated peroxide were lighter in colour than those obtained under similar conditions but in the absence of TAED. In comparison, the isolated eight hemicellulosic samples were analysed by both degraded methods such as acid hydrolysis and alkaline nitrobenzene oxidation, and non-degradation techniques e.g. FT-IR and 13C-NMR spectroscopy, and gel permeation chromatography. Results showed that the post-treatment with TAED activated peroxide did not oxidize the hydroxyl groups in hemicelluloses and neither affect the overall structure of the macromolecules. Thermal stability of the residual hemicellulosic samples was studied using thermogravimetric analysis and differential scanning calorimetry.