Sodium Metabisulfite powder for paper bleaching

Introduction to Sodium Metabisulfite

Sodium Metabisulfite is a white crystalline powder with a chemical formula of Na2S2O5 and a molecular weight of 190.11 g/mol. In paper bleaching, it is widely used as an effective bleaching agent. Its high solubility and reducing properties make it ideal for use in paper bleaching processes.


The role of Sodium Metabisulfite in paper bleaching

The main function of Sodium Metabisulfite is to release sulfurous acid gas (SO2). Sulfurous acid gas has strong bleaching and sanitizing properties, effectively removing pigments and impurities from paper. It is able to chemically react with colored substances and convert them into colorless compounds to achieve bleaching effects.


Sulfurous acid gas has strong bleaching and disinfecting properties, which can effectively remove pigments and impurities from paper, making it whiter.


The bleaching process involves a chemical reaction between sulfurous acid gas and colored substances in the paper. Sulfurous acid gas, as a reducing agent, undergoes a reduction reaction with the compounds in the colored substances, converting them into colorless compounds. These colored compounds include pigments, cellulose-attached impurities, lignin, etc., which bring undesirable colors and impurities to paper.


Sodium Metabisulfite is added to the paper system in the form of powder during the bleaching process. When paper comes into contact with a bleach solution containing Sodium Metabisulfite, Sodium Metabisulfite dissolves rapidly and releases sulfurous acid gas. Sulfurous acid gas diffuses through the paper and reacts with the colored substance, reducing it to a colorless substance. This chemical reaction gives the paper its bright white color and removes contamination from pigments and impurities.


By using Sodium Metabisulfite for paper bleaching, efficient, fast and thorough bleaching results can be achieved. The powerful bleaching and sanitizing properties of sulfurous acid gas ensure improved paper quality and appearance. At the same time, Sodium Metabisulfite, as a commonly used and affordable bleaching agent, provides a feasible solution for the paper industry.


It can be seen that Sodium Metabisulfite effectively removes pigments and impurities in paper by releasing sulfurous acid gas and utilizing its powerful bleaching and disinfection properties. Its application can make the paper whiter, improve the quality and market competitiveness.


Data support

Studies have shown that paper bleaching with Sodium Metabisulfite can achieve significant bleaching results in a short period of time. In the experiment, the paper sample containing pigment was soaked in a bleach solution containing an appropriate amount of Sodium Metabisulfite, and the bleaching effect could be significantly observed within 5 minutes. At the same time, the experiment also measured the bleaching effect of different concentrations of Sodium Metabisulfite solutions, and the results showed that with the increase of the concentration of Sodium Metabisulfite in the solution, the bleaching effect gradually increased.


Practical Cases

A specific case is the pulp and paper industry. In this industry, the bleaching of paper is a critical step in ensuring the quality and whiteness of the final product. Sodium Metabisulfite is widely used as a paper bleach because of its high efficiency in removing pigments and contaminants from paper. In the paper bleaching process, Sodium Metabisulfite is added to the pulp, and the sulfurous acid gas reacts with the colored substances in the paper to achieve the bleaching effect. This not only improves the appearance and quality of the paper, but also increases the market competitiveness of the final product.


Environmental and Economic Benefits

In addition to its remarkable role in paper bleaching, Sodium Metabisulfite also has environmental and economic benefits. Sodium Metabisulfite is a more environmentally friendly choice compared to other bleaches, such as chlorine bleach. It does not produce harmful by-products such as chlorides and organic halides. Furthermore, the relatively low cost of Sodium Metabisulfite is crucial for the sustainable development of the pulp and paper industry.



Sodium Metabisulfite powder plays a key role in paper bleaching. Its sulfurous acid gas releasing capability and chemical properties make it an efficient, environmentally friendly and affordable bleach. With the support of data and cases, we can clearly see the actual effect of Sodium Metabisulfite in the paper bleaching process. It can not only improve the whiteness and quality of paper, but also make an important contribution to the sustainable development of the pulp and paper industry. Therefore, Sodium Metabisulfite is an indispensable and important component in the paper bleaching process.



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