title: Structural characterization of lignin in the process of cooking of cornstalk with solid alkali and active oxygen.
abstract: A novel, efficient, and environmentally friendly technology is used in cornstalk cooking, active oxygen (O₂ and H₂O₂) cooking with solid alkali (MgO). After the cooking, the milled wood lignin in the raw material and pulp and the water-soluble and insoluble lignin in the yellow liquor were all characterized by attenuated total reflectance Fourier transform infrared spectroscopy and two-dimensional heteronuclear single-quantum coherence NMR. The results showed that the cooking procedure with solid alkali and active oxygen had a high selectivity for delignification, which could remove 85.5% of the lignin from the raw material. The syringyl (S/S'/S') units could be dissolved preferentially because of their high reactivity, and a novel guaiacyl unit with a carbonyl group (G') was generated in the cooking process. Moreover, during the cooking, the β-O-4' (A/A'/A″) structures as the main side-chain linkages in all the lignins could be partly broken and the β-O-4' (A') with a ring-conjugated structure was readily attacked by oxygen, whereas the H unit and β-5' and β-β' structures were found to stay stable without characteristic reaction.
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, Guangdong Province, China.
authors.forename: Qiulin
authors.initials: Q
authors.lastname: Yang
authors.forename: Jianbin
authors.initials: J
authors.lastname: Shi
authors.forename: Lu
authors.initials: L
authors.lastname: Lin
authors.forename: Junping
authors.initials: J
authors.lastname: Zhuang
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Pang
authors.forename: Tujun
authors.initials: T
authors.lastname: Xie
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000468:Alkalies / Q000737:chemistry*; D002236:Carbohydrate Conformation; D006358:Hot Temperature; D007202:Indicators and Reagents / Q000737:chemistry* / Q000302:isolation & purification; D008031:Lignin / Q000737:chemistry* / Q000302:isolation & purification; D018547:Plant Stems / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry*; D003313:Zea mays / Q000737:chemistry*
chemical_list: D000468:Alkalies; D007202:Indicators and Reagents; D017382:Reactive Oxygen Species; D008031:Lignin