Morphological changes of lignin during separation of wheat straw components by the hydrothermal-ethanol method

Jinbao Li; Pan Feng; Huijuan Xiu; Jingyu Li; Xue Yang; Feiyan Ma; Xiang Li; Xuefei Zhang; Evguenii Kozliak; Yun Ji

doi:10.1016/j.biortech.2019.122157

Morphological changes of lignin during separation of wheat straw components by the hydrothermal-ethanol method

Bioresour Technol. 2019 Dec:294:122157. doi: 10.1016/j.biortech.2019.122157. Epub 2019 Sep 17.

Authors

Jinbao Li¹, Pan Feng², Huijuan Xiu³, Jingyu Li², Xue Yang², Feiyan Ma², Xiang Li⁴, Xuefei Zhang⁵, Evguenii Kozliak⁶, Yun Ji⁷

Affiliations

¹ Shaanxi University of Science & Technology, National Demonstration Center for Experimental Light Chemistry Engineering Education, Xi'an 710021, China; Shaanxi Province Key Lab of Papermaking Technology and Specialty Paper, Shaanxi University of Science & Technology, Xi'an 710021, China.
² Shaanxi University of Science & Technology, National Demonstration Center for Experimental Light Chemistry Engineering Education, Xi'an 710021, China.
³ Shaanxi University of Science & Technology, National Demonstration Center for Experimental Light Chemistry Engineering Education, Xi'an 710021, China. Electronic address: xiuhuijuan@sust.edu.cn.
⁴ College of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China.
⁵ Department of Chemical Engineering, University of North Dakota, Grand Forks, ND 58202, USA.
⁶ Department of Chemistry, University of North Dakota, Grand Forks, ND 58202, USA.
⁷ Department of Chemical Engineering, University of North Dakota, Grand Forks, ND 58202, USA. Electronic address: yun.ji@engr.und.edu.

PMID: 31557653
DOI: 10.1016/j.biortech.2019.122157

Abstract

The separation efficiencies of wheat straw components by hydrothermal treatment and ethanol extraction have been compared. The results showed that the lignin removal rate by two-step hydrothermal-ethanol method was significantly lower than that of single-step ethanol extraction. Microscopic and adsorption studies (using SEM/AFM, XPS and pore structure analysis) showed that during the hydrothermal treatment a large lignin fraction migrated from the intercellular layer and cell wall and deposited on the fiber surface. Furthermore, the deposited lignin then spread on the fiber surface to form a lignin coating layer, which prevented its dissolution in ethanol. Without prior heating, i.e., upon a single step ethanol extraction, the massive lignin deposition was avoided, presumably due to its efficient dissolution hindering its tight binding with carbohydrate polymers on the fiber surface. Therefore, the lignin removal efficiency was drastically reduced as a result of hydrothermal treatment compared to ethanol extraction.

Keywords: Biomass component separation; Ethanol extraction; Hydrothermal treatment; Lignin; Wheat straw.

MeSH terms

Adsorption
Cell Wall
Ethanol
Lignin*
Triticum*

Substances

Ethanol
Lignin