Why is pulp bleached?

Why is pulp bleached?

Mechanical pulp retains most of the lignin present in the wood used to make the pulp and thus contain almost as much lignin as they do cellulose and hemicellulose. Therefore, the objective of bleaching mechanical pulp (also referred to as brightening) is to remove only the chromophores (color-causing groups).

What is the process of bleaching?

Bleaching is the process of decolorization of raw textile material by removing inherent and or acquired coloring components from the fiber. It provides base whiteness to the textile material which could be further whitened with the help of optical brighteners or dyed | printed depending on the desired end use.

What is the main purpose of bleaching?

bleach, solid or liquid chemical used to whiten or remove the natural colour of fibres, yarns, other textiles, and paper. In textile finishing, the bleaching process is used to produce white cloth, to prepare fabrics for other finishes, or to remove discoloration that has occurred in other processes.

What is meant by bleaching action?

The bleaching action of Chlorine is permanent because it involves the process of oxidation. Chlorine reacts with water to produce nascent oxygen. This oxygen combines with the colours material and makes it colourless. It a powerful oxidising agent.

What is characteristic of bleach?

The active agent in liquid bleach is sodium hypochlorite, which gives the product a light greenish yellow tinge and its characteristic chlorine smell. Liquid bleach usually contains also some sodium hydroxide (caustic soda or soda lye, NaOH), intended to keep the solution alkaline.

Which polluting chemicals are coming out of bleaching DED process?

The chemistry of bleaching agents is predominantly that of oxidizing agents: chlorine (Cl2) and some of its compounds or peroxygen species such as hydrogen peroxide (H2O2), ozone (O3), and sodium perborate (NaBO3).