Analysis of degradation products and structural characterization of giant reed and Chinese silvergrass pretreated by 60Co-γ irradiation

Radiation pretreatment of lignocellulosics has been widely applied for the breakdown of the stubborn cellulose structure to enable the cellulose to be more accessible to cellulolytic enzymes. However, the effects of gamma irradiation on the lignocellulosics structure changes and the composition of pretreatment degradation products are not well understood. In this study, the influences of irradiation dose on the microstructure and irradiated-degradation components of cellulose under Co-6 gamma-irradiation (0-1200 kGy) was comprehensively investigated using giant reed and Chinese silvergrass as model substrate. The microstructure of biomass was examined with Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Additionally, composition determination and degradation products were analyzed. FT-IR analysis show that irradiation destroyed the glycosidic bond and inter- and intramolecular hydrogen bond of cellulose. XRD and SEM analyses confirm that irradiation could damage the crystalline microstructure and surface morphology of lignocellulosics. Ion chromatography analysis demonstrates that there exist fermentation sugars such as glucose, xylose, arabinose, galactose and cellobiose. Moreover, some potential inhibitors, such as glucuronic acid, galacturonic acid, methanoic acid, acetic acid, furfuraldehyde and p-coumaric acid, were detected in the irradiation-derived degradation products. Irradiation dose exhibited obvious influences on the production of these products. These investigations would be helpful for further understanding the applications and fundamentals of gamma irradiation pretreatment for bioethanol production from lignocellulosics. (c) 2016 Elsevier B.V. All rights reserved.