Enhanced Enzymatic Hydrolysis and Structural Features of Corn Stover by NaOH and Ozone Combined Pretreatment
1
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
2
Bio-Pharmaceutical College, Beijing City University, Beijing 100094, China
*
Author to whom correspondence should be addressed.
Molecules 2018, 23(6), 1300; https://doi.org/10.3390/molecules23061300
Received: 19 March 2018 / Revised: 19 April 2018 / Accepted: 8 May 2018 / Published: 29 May 2018
(This article belongs to the Special Issue Efficient Technology for the Pretreatment of Biomass)
A two-step pretreatment using NaOH and ozone was performed to improve the enzymatic hydrolysis, compositions and structural characteristics of corn stover. Comparison between the unpretreated and pretreated corn stover was also made to illustrate the mechanism of the combined pretreatment. A pretreatment with 2% (w/w) NaOH at 80 °C for 2 h followed by ozone treatment for 25 min with an initial pH 9 was found to be the optimal procedure and the maximum efficiency (91.73%) of cellulose enzymatic hydrolysis was achieved. Furthermore, microscopic observation of changes in the surface structure of the samples showed that holes were formed and lignin and hemicellulose were partially dissolved and removed. X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance (CP/MAS 13C-NMR) were also used to characterize the chemical structural changes after the combined pretreatment. The results were as follows: part of the cellulose I structure was destroyed and then reformed into cellulose III, the cellulose crystal indices were also changed; a wider space between the crystal layer was observed; disruption of hydrogen bonds in cellulose and disruption of ester bonds in hemicellulose; cleavage of bonds linkage in lignin-carbohydrate complexes; removal of methoxy in lignin and hemicellulose. As a result, all these changes effectively reduced recalcitrance of corn stover and promoted subsequent enzymatic hydrolysis of cellulose.
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Keywords:
corn stover; alkali; ozone; combined pretreatment; enzymatic hydrolysis; surface morphology; structural characteristics
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MDPI and ACS Style
Wang, W.; Zhang, C.; Tong, S.; Cui, Z.; Liu, P. Enhanced Enzymatic Hydrolysis and Structural Features of Corn Stover by NaOH and Ozone Combined Pretreatment. Molecules 2018, 23, 1300. https://doi.org/10.3390/molecules23061300
AMA Style
Wang W, Zhang C, Tong S, Cui Z, Liu P. Enhanced Enzymatic Hydrolysis and Structural Features of Corn Stover by NaOH and Ozone Combined Pretreatment. Molecules. 2018; 23(6):1300. https://doi.org/10.3390/molecules23061300
Chicago/Turabian StyleWang, Wenhui; Zhang, Chunyan; Tong, Shisheng; Cui, Zhongyi; Liu, Ping. 2018. "Enhanced Enzymatic Hydrolysis and Structural Features of Corn Stover by NaOH and Ozone Combined Pretreatment" Molecules 23, no. 6: 1300. https://doi.org/10.3390/molecules23061300
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