Sodium Hydrosulphite (90%) - China

Brief Overview

Sodium hydrosulphite, also known as sodium dithionite, is a white crystalline powder with the chemical formula Na₂S₂O₄. It is a powerful reducing agent with a pungent sulfur-like odor and is soluble in water but unstable in acidic or moist environments. Sodium hydrosulphite is available in various commercial grades, typically distinguished by their purity levels — commonly 90% and 88%. The compound is widely used in textile processing, water treatment, paper manufacturing, and chemical synthesis.
 

Manufacturing Process

Sodium hydrosulphite is typically produced through two main industrial processes:

Zinc Process: Sodium bisulfite is reduced using zinc dust in the presence of sodium hydroxide to form sodium hydrosulphite. This process is known for producing high-purity material.

Formate Process: Sodium formate is used as the reducing agent, in a reaction with sodium bisulfite and formaldehyde under controlled conditions. This method is considered more environmentally friendly and is commonly used in modern production.

The final product is filtered, crystallized, and dried to meet desired purity levels such as 90% and 88%.

 

Textile Industry

Sodium hydrosulphite (especially 90% and 88% grades) is extensively used in the textile industry for vat dyeing, reduction clearing, and bleaching of synthetic fibers like polyester. Its strong reducing properties make it ideal for removing excess dye and improving color fastness.

Paper and Pulp Industry

It is used as a bleaching agent for mechanical paper pulp (e.g., groundwood) and de-inking recycled paper. Sodium hydrosulphite effectively reduces chromophores, enhancing brightness and whiteness.

Water Treatment

As a reducing agent, sodium hydrosulphite is used to remove residual chlorine, chloramines, and other oxidants from industrial water and wastewater streams.

Chemical Industry

In chemical manufacturing, it serves as a reducing agent in organic synthesis, particularly for compounds sensitive to oxidation. It's also used in the production of sulfur dyes and various specialty chemicals.

Leather Processing

Sodium hydrosulphite is used in the leather industry for the bleaching of animal hides, helping to achieve uniform coloration and improve texture.