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Bleaching of wood pulp is the chemical processing of wood pulp to lighten its color and whiten the pulp. The primary product of wood pulp is paper, for which whiteness (similar to, but distinct from brightness) is an important characteristic.
Pulp bleaching is the process where wood pulp fibres are chemically treated before paper-making to remove lignin and resins. Pulp bleaching results in white and clean paper products. Dioxins and furans are toxic chemical compounds mostly formed during bleaching with elemental chlorine.
Kraft pulp is darker than other wood pulps, but it can be bleached to make very white pulp. Fully bleached kraft pulp is used to make high-quality paper where strength, whiteness, and resistance to yellowing are important. The kraft process can use a wider range of fiber sources than most other pulping processes.
Bleached Hardwood Kraft Pulp (BHKP) is commonly used in paperboard and specialty paper, as well as in coated and uncoated papers and tissue. In many applications, hardwood pulp provides excellent strength, smoothness and surface properties due to its chemical and physical fibre structure.
11 de jun. de 2019 · PDF | The bleaching of pulp involves the increase in brightness of chemical, mechanical, ... performed by oxidizing wood pulp with potassium permanganate under standard-ized conditions (7, 8).
Further purification can be accomplished by bleaching. Chemical wood pulp that is purified both by bleaching and by alkaline extraction is called alpha or dissolving pulp. It is used for specialty papers, for rayon and cellulose film production, and for cellulose derivatives, such as nitrate and acetate.
The BCTMP (bleached chemi-thermomechanical pulp) process is a mechanical pulping technology which uses sodium sulfite for impregnation. ANDRITZ has developed new and improved technologies which are superior to the conventional BCTMP process. The BCTMP technology is used for both softwood and hardwood prior to the first refining stage.
