What Role Do Chlorine Play In Paper Industry

October 15, 2021

Chlorine is a chemical element and is present in various compounds. It belongs to the halogen group. It is usually observed in the form of a yellow and green gas at room temperature and has a pungent smell.

It is a highly reactive element and a strong agent for oxidization. Chlorine functions as a bleaching agent during the manufacturing process of paper. Usually, chlorine dioxide is used to make paper and works as a bleaching agent for wood pulp.

Pulp and paper industry:

Chlorine gives the paper a whitish appearance and helps remove lignin present in the wood fiber that causes the paper to turn yellow when it is exposed to sunlight. Pulp bleaching is one of the processes through which the wooden particles turn whiter and brighter.

Bleaching of pulp:

Bleaching of paper pulp is widely used for manufacturing colored and white paper. Furthermore, the process also balances the finished product and removes foreign particles and dirt. Read the points below to know more about pulp bleaching using liquid chlorine.

1.The process of pulp bleaching removes lignin that makes the paper turn brown when exposed to sunlight.
2.Paper turns brighter and whiter due to the addition of chlorine.
3.Typically, the removal of lignin takes place in the stage of cooking. Still, it is hard to remove it completely during the cooking stage that eventually causes the fiber to damage.
4.The bleaching process involving the use of a chlorine cylinder begins early during the stage of pulp cooking.
5.The pulp bleaching with chlorine takes place in various stages to achieve the best outcome and prevent the damage of cellulose fibers.
6.Bleaching of pulp is one of the vital processes taking place in the paper industry in multiple sequences.
7.As chlorine is primarily responsible for the oxidation of pulp, it results in the extraction of more lignin. Furthermore, an alkali is used for removing lignin from the exterior surface of the pulp.
8.Bleaching with chlorine dioxide makes the paper highly bright without harming the pulp, but chlorine usage needs to stay restricted to the pulp and paper mill.
9.Even though hydrogen peroxide is another compound required for bleaching, it is highly expensive, making chlorine one element in pulp bleaching.

Understand the process of pulp bleaching:

Most people are aware of the use of chlorine for water treatment, but the pulp bleaching industries depend on chlorine heavily. The bleaching process may occur in various stages, such as using chlorine and moving on to alkali extraction and then a couple of treatments using chlorine dioxide. Read the points below to gain knowledge about the process of pulp bleaching.

1.Between every stage of pulp bleaching, the pulp needs to undergo washing for the removal of lignin.
2.Not all kinds of pulp require bleaching except cardboard and sine newspapers.
3.Due to the growing demand for bleached paper, chlorine manufacturers need to supply chlorine promptly to meet the increasing demands.

Mixing during bleaching of pulp:

Thorough mixing is generally a key aspect of pulp bleaching. A high-quality and industrial-grade mixing equipment may be needed to make the process accurate.

The final take:

Due to differences in the properties of the bleaching agents, the bleaching process disintegrates into two categories. The first process is the removal of lignin using chlorine dioxide, chlorine, hypochlorite, peroxide, ozone, and oxygen, which takes place in chemical pulp bleaching. Besides, bleaching may also be needed for retaining lignin.

To manufacture paper with long-term preservation, using chlorine and chlorine dioxide to remove colored substances and debris helps retain the whiteness of the paper and allows it to last longer. Therefore, chlorine plays a vital role in the paper industry.

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