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Complete recovery of cellulose from rice straw pretreated with ethylene glycol and aluminum chloride for enzymatic hydrolysis

Tang, Song, Dong, Qian, Fang, Zhen, Miao, Zheng-diao
Bioresource technology 2019 v.284 pp. 98-104
Fourier transform infrared spectroscopy, X-ray diffraction, adsorption, aluminum chloride, cellulose, delignification, endo-1,4-beta-glucanase, enzymatic hydrolysis, ethylene glycol, fractionation, glucose, hemicellulose, hydrolysis, lignin, lignocellulose, rice straw, scanning electron microscopy, thermogravimetry
Rice straw was pretreated with ethylene glycol (EG) and AlCl3 for enzymatic hydrolysis. EG-AlCl3 pretreatment had an extremely good selectivity for component fractionation, resulting in 88% delignification and 90% hemicellulose removal, with 100% cellulose recovered or 76% (w/w) cellulose content in solid residue at 150 °C with 0.055 mol/L AlCl3. The pretreated residue (5%, w/v) presented a higher enzymatic hydrolysis rate (glucose yield increased 2 times to 94%) for 24 h at cellulase loading of 10 FPU/g. The hydrolysis behavior was correlated with the composition and structure of substrates characterized by SEM, FT-IR, BET, XRD and TGA. The enzyme adsorption ability of pretreated straw was 12-folds that for the original sample. EG-AlCl3 solution was further cycled for 3 times with 100% cellulose recovery but only 29% lignin removal due to the loss of AlCl3. EG-AlCl3 pretreatment is an efficient method with little loss of cellulose for lignocelluloses.