Views: 2 Author: Site Editor Publish Time: 2022-05-02 Origin: Site
Lignin (Latin, English, German: lignin) is a kind of complex organic polymer, which forms important structural materials in the supporting tissues of vascular plants and some algae. Lignin is particularly important in the formation of cell walls, especially in wood and bark, because they give rigidity and are not easy to decay. Chemically, lignin is a cross-linked phenolic polymer.
The xylem of plants (a structure responsible for transporting water and minerals) contains a large amount of lignin, which maintains a very high hardness to support the weight of the whole plant.
Lignin is a biopolymer with three-dimensional network structure formed by the interconnection of three phenylpropane units through ether bond and carbon carbon bond. It is rich in aromatic ring structure, aliphatic and aromatic hydroxyl groups, quinone groups and other active groups.
Lignin is an amorphous polymer composed of phenylpropane units connected by carbon carbon bond and ether bond. It is the second largest biomass resource in the plant world after cellulose. As a typical biomass material, lignin is one of the rare renewable resources in aromatic compounds. Lignin is the second largest resource of biomass materials in the plant world after cellulose. The global annual output is about 50 million tons, of which lignin from agricultural residues accounts for about 10% ~ 20%, and lignin from forest biomass materials accounts for about 20% ~ 30%. It has a wide range of sources and huge output. Lignin has amorphous disordered structure, phenylpropane is its basic structural unit, which comes from three aromatic alcohol precursors, which are β- Coumarin, coniferol and mustard alcohol correspond to three types of lignin, namely p-hydroxyphenyl lignin, purple eugenol lignin and guaiacyl lignin respectively.
Lignin is mainly located between cellulose fibers and plays a compressive role. Among woody plants, lignin accounts for 25%, which is the second most abundant organic matter in the world (cellulose is the first). Because lignin, cellulose and hemicellulose are often connected with each other in nature to form lignin carbohydrate complex, there is no way to separate the original lignin whose structure is completely intact.
According to the difference of lignin composition, it can be divided into three categories
Guaiacol mustard alcohol lignin
Guaiacol mustard alcohol p-hydroxybenzene lignin