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Kraft lignin from black liquor, which is produced in much higher amounts, may be processed into sulfonated lignin. The lignin is first precipitated by acidifying the liquor with CO 2 then washed (other methods for isolation exist). Reaction with sodium sulfite or sodium bisulfite and an aldehyde under a basic environment completes sulfonation.
Lignin was first mentioned in 1813 by the Swiss botanist A. P. de Candolle, who described it as a fibrous, tasteless material, insoluble in water and alcohol but soluble in weak alkaline solutions, and which can be precipitated from solution using acid. [3] He named the substance "lignine", which is derived from the Latin word lignum, [4 ...
The lignin is converted to lignosulfonates, which are soluble and can be separated from the cellulose fibers. For the production of cellulose, the sulfite process competes with the Kraft process which produces stronger fibers and is less environmentally costly. idealized scheme for lignin depolymerization by the Sulfite process.
The black liquor is an aqueous solution of lignin residues, hemicellulose, and the inorganic chemicals used in the process. The black liquor comprises 15% solids by weight of which two thirds are organic chemicals and the remainder are inorganic. [3] Normally the organics in black liquor are 40-45% soaps, [4] 35-45% lignin and 10-15% other ...
The term "lignin characterization" (or "lignin analysis") refers to a group of activities within lignin research aiming at describing the characteristics of a lignin by determination of its most important properties. [1] Most often, this term is used to describe the characterization of technical lignins by means of chemical or thermo-chemical ...
Coniferyl alcohol is an organic compound with the formula HO(CH 3 O)C 6 H 3 CH=CHCH 2 OH. A colourless or white solid, it is one of the monolignols, produced via the phenylpropanoid biochemical pathway. When copolymerized with related aromatic compounds, coniferyl alcohol forms lignin or lignans. [1] [2] [3] Coniferin is a glucoside of ...
The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na 2 S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper.
The results produce fibers that are screened and bleached for paper products. At these conditions, the lignin is dissolved in organic solvent and hemicelluloses are used to produce more organic solvent. Organic solvents are collected by separating water from the cooking liquor and then the lignin is precipitated by adding water, heat, and ...