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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 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 ...
Chemical pulp is produced by combining wood chips and chemicals in large vessels called digesters. There, heat and chemicals break down lignin, which binds cellulose fibres together, without seriously degrading the cellulose fibres. Chemical pulp is used for materials that need to be stronger or combined with mechanical pulps to give a product ...
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 ...
Guaiacol (/ ˈ ɡ w aɪ ə k ɒ l /) is an organic compound with the formula C 6 H 4 (OH)(OCH 3). It is a phenolic compound containing a methoxy functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish. It occurs widely in nature and is a common product of the pyrolysis of wood. [3]
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.
In this process lignin and hemicellulose are typically separated from the plant material leaving the fibrous cellulose component to be processed for paper production, or 'chemical cellulose'. [13] Through the pulp process most of the lignin is removed and discharged as waste material in the form of effluent/wastewater before then being used as ...