Sodium dithionite, also known as insurance powder, is an inorganic compound with the chemical formula Na2S2O4. It is a white crystalline powder with an odor of sulfur dioxide. This substance has a variety of properties, including strong reduction and instability. It has a melting point of 300 °C, a boiling point of up to 1390 °C, and a density of about 2.13 g/cm³. Due to its chemical nature, sodium dithionite is easily oxidized in the air, reacts violently with water and may burn, so special care is required when using and storing it.

Sodium dithionite is a chemical with a wide range of uses, mainly due to its strong reducing and bleaching properties. Here are some of the main uses of sodium bisulfite:

1. Textile industry: In the textile industry, sodium bisulfite is used as a bleaching agent and decolorizing agent to help remove pigments from fibers such as cotton and linen to make them whiter.

2. Paper industry: The paper industry also uses sodium bisulfite as a bleaching agent to improve the whiteness and brightness of the paper.

3. Food industry: In food processing, sodium bisulfite is used for the bleaching of candied fruits, dried fruits, dried vegetables, vermicelli and other foods to improve their appearance quality.

4. Leather and fur industry: Sodium bisulfite is used in leather and fur processing for bleaching and decolorization to improve the appearance of the final product.

5. Chemical synthesis: In organic chemical synthesis, sodium bisulfite is used as a reducing agent and participates in a variety of chemical reactions, such as the synthesis of dyes, pharmaceuticals and other chemicals.

6. Disinfectants and antioxidants: Sodium bisulfite is also used as an ingredient in some disinfectants and antioxidants.

7. Metal refining: In the metallurgical industry, sodium bisulfite is used in the refining and refining process of metals as a reducing agent to help extract metals.

8. Other applications: In addition to the above uses, sodium bisulfite may also be used in other industrial processes, such as special treatment in plastics, rubber, cosmetics and other industries.