The Effect of Irradiation Combined with Sodium Hydroxide Pretreatment on Component, Structure, Utilization Efficiency of Phragmites Australis

• Published in: Waste and biomass valorization 2024-12, Vol.15 (12), p.6615-6633
• Main Authors: Qi, Hui, Wu, Xiaofen, Chen, Liang, Liu, An, Deng, Ming, Wei, Dongning, Wang, Danyang, Peng, Zhili, Wang, Keqin
• Format: Article
• Language: English
• Subjects: Aquatic plants; Biofuels; Caustic soda; Cellulose; Covalent bonds; Crop production; Crystal structure; Efficiency; Engineering; Environment; Environmental Engineering/Biotechnology; Ethanol; Fermentation; Fourier transforms; Gas chromatography; Hemicellulose; Hydrogen bonds; Hydrolysis; Industrial Pollution Prevention; Infrared analysis; Infrared spectroscopy; Irradiation; Lignin; Lignocellulose; Mass spectrometry; Mass spectroscopy; Original Paper; Pretreatment; Renewable and Green Energy; Saccharification; Scanning electron microscopy; Sodium hydroxide; Utilization; Waste Management/Waste Technology; X-ray diffraction
• ISSN: 1877-2641; 1877-265X
• DOI: 10.1007/s12649-024-02571-8

Phragmites australis (Reed) is an excellent lignocellulosic crop for bioethanol production, but its recalcitrant structure affects utilization efficiency. Therefore, the effective pretreated method to destroy the complex and tight structure was necessary. In this study, Irradiation (0,400,800 kGy) combined with sodium hydroxide (NaOH) (0,1%,2%,4%) pretreatment was used for the deconstruct lignocellulose structure of reed stalk, and the residue after pretreatment were subjected to enzymatic hydrolysis and synchronous saccharification and fermentation (SSF). Scanning electron microscope (SEM), Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to determine the structural changes of reed stalk after different pretreatment. Gas Chromatography and Mass Spectrometry (GC/MS) was used to analysis the main lignocellulose-derived inhibitor produced by pretreatment. The results demonstrated that irradiation combined with NaOH pretreatment could destroy the lignocellulose structure, remove the lignin and hemicellulose partially, increase the content of cellulose, and promote fermentable sugar content for ethanol fermentation. The maximum enzymatic hydrolysis conversion rate of cellulose was 85.02% when the reed stalk was treated by 800 kGy irradiation combined with 4% NaOH solution. The maximum ethanol conversion rate was 73.35% when the reed stalk was pretreated by 800 kGy irradiation combined with 2% NaOH solution. Irradiation pretreatment destroyed the tightly packed structure, induced the fracture of hydrogen bond or covalent bond of reed stalk lignocellulose, broken the crystal structure of cellulose. Irradiation combined with NaOH treatment, the characteristic peak intensity of hemicellulose and lignin decreased or even disappeared in FT-IR spectroscopy. Interestingly, the cellulose crystal form transformed from I to II, when the reed stalk was treated by 800 kGy irradiation combined with NaOH solution. Overall, irradiation combined with NaOH pretreatment was effective for improving the utilization efficiency of reed stalk. Graphical Abstract