Sodium Hydrosulfite is a white, crystalline, water-soluble powder,with a formula Na2S2O4. It used as a reducing agent, especially in dyeing, and as a bleach. Sodium hydrosulfite is a very effective reducing agent.
It also know as Sodium Dithionite had been developed at the beginning of the 20th century and was first applied for textile printing. Due to structural change in the textile industry, the importance of the application for the bleaching of wood pulp in the paper industry increased continuously.
Applications of Sodium hydrosulfite
Sodium hydrosulfite is commonly used in the pulp and paper industry for bleaching brightening and de-colorization of virgin and recycled fiber. It is also applied extensively to brighten Kaolin clay. In textiles, the primary usage is in processing vat dyes and indigo dyes. Other applications include water treatment, leather processing and food bleaching (sugar, honey and gelatin).
Some industries that commonly rely on sodium hydrosulfite in the manufacture of their products include:
- Textiles as a reducing agent for color
- Pulp and paper as an additive and reducing agent
- Foods and beverages
- Chemical processing
- Water treatment – for controlling iron flash on white fabrics in bleaching environments
- Gas purification
- Environmental remediation