Characterize the physicochemical structure and enzymatic efficiency of agricultural residues exposed to γ-irradiation pretreatment
2020
Wu, Xiaofen | Ma, Yukun | He, Wenqiang | Qi, Hui | Zhang, Yong | Zhou, Yiji | Su, Xiaojun | Deng, Ming | Wang, Keqin
Gamma irradiation technology has become a very promising pretreatment method in lignocellulosic bioethanol production. In this work, the enzymatic efficiency and physicochemical structure of rice straw, corn stalk and rapeseed straw treated by gamma irradiation were studied. Compared with un-irradiated samples, the particle size was much smaller with the irradiation absorbed dose increased, the milling energy consumption was saved by 64.40, 66.62 and 71.68 %, respectively, for rice straw, corn stalk and rapeseed straw irradiated with 600 kGy. Irradiation pretreatment significantly improved the enzymatic hydrolysis efficiency of agricultural residues, the glucan conversion rates in enzymatic hydrolysis of 800 kGy treated rice straw, corn stalk and rapeseed straw were 72.42, 69.79 and 72.68 %, respectively, it was 4.78, 3.82 and 4.35 times higher than untreated samples at solid consistency of 7.5 % and enzyme loading of 15 FPU/g. In addition, irradiation pretreatment decomposed cellulose and hemicellulose to water-soluble oligosaccharides, damaged apparent morphology of agricultural residues, ruptured hydrogen bond of lignocelluloses molecular, broken the glycosidic bond of cellulose and hemicellulose, destroyed the crystal structure of cellulose, and decreased the thermal stability of agricultural residues by FT-IR, XRD, TG/DTG and NREL procedure analysis.
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