Structure, Morphology, Thermostability and Irradiation-Mediated Degradation Fractions of Hemicellulose Treated with γ-Irradiation

Abstract

To elucidate the physicochemical properties and degradation mechanism of hemicellulose treated with irradiation doses (from 0 to 1200 kGy), a set of experiments on hemicellulose morphology, structure, molecular weight, free radicals, thermal stability, and irradiation mediated fractions was performed. Fourier transforms infrared spectroscopy and nuclear magnetic resonance analyses show that irradiation destroys the inter- and intra-molecular hydrogen bonds of hemicellulose leading to the generation of reductive carbonyl group. Scanning electron microscope, electron paramagnetic resonance and gel permeation chromatography measurements further confirm that the damage degree of hemicellulose structure and morphology surface in dependence on irradiation doses. Thermogravimetry/differential thermogravimetry analyses indicate that the activated energy and thermal stability of irradiated hemicellulose decrease with the increasing of absorbed dose. Irradiation mediated degradation compounds analyses by ion chromatography reveal that xylose (7.64 ± 0.92 mg g−1), and arabionose (3.58 ± 0.08 mg g−1) and cellubiose (0.27 ± 0.00 mg g−1) are observed at 1200 kGy. Amount of glucuronic acid (3.61 ± 0.02 mg g−1) and galacturonic acid (7.44 ± 0.38 mg g−1), which are respectively derived from glucose and galactose, are also obtained in the water soluble irradiation mediated degradation fraction. These data provide a basis support on a full utilization of hemicellulose after γ-irradiation pretreatment.