Sodium dithionite

Sodium dithionite (CAS 7775-14-6) is an inorganic reducing salt sold under trade names including Hydros, Blankit, Vatrolite, and Burmol. It carries no E-code designation and is not classified as a food additive under EU regulations. It is commercially available at technical and food-contact grades.

In textile processing, sodium dithionite reduces insoluble vat dyes to their soluble leuco form, enabling fibre uptake before re-oxidation fixes the colour. In pulp and paper production, it bleaches mechanical pulp by chemically reducing chromophoric groups responsible for yellowing, without dissolving the lignin matrix. Water treatment applications exploit its oxygen-scavenging capacity to remove dissolved oxygen from process water.

Sodium dithionite is supplied as a white powder in technical and food-contact grades, with purity levels typically ranging from 85% to 90% active content. It falls under REACH registration requirements within the EU. Standard packaging includes 25 kg bags and bulk quantities, with HS code 28311010 applicable for import and export documentation.