Thiourea dioxide

Thiourea dioxide (CAS 1758-73-2), also known as formamidinesulfinic acid and abbreviated as TDO, is a reductive bleaching and reducing agent used across textile, paper, and leather processing industries. It acts as a controlled source of reducing power under alkaline and elevated-temperature conditions, enabling selective bleaching and color stripping without the aggressive fiber damage associated with oxidative systems.

In textile processing, TDO is used for reductive clearing after dyeing with disperse dyes on polyester, removing unfixed surface dye to improve wash fastness and color brightness. Pulp and paper producers apply it for bleaching mechanical and chemical pulps, particularly where brightness reversion needs to be minimized during the manufacturing process.

Leather processors use it to achieve uniform whitening of hides prior to dyeing, ensuring consistent color uptake across the finished material and improving the final aesthetic quality. In water treatment and industrial effluent applications, it functions as a reducing agent to neutralize residual oxidants such as chlorine and chromate compounds found in waste streams.

Thiourea dioxide is supplied as a white crystalline powder. Standard commercial grades include technical grade for industrial processing applications, with purity typically specified at 98% or higher. Packaging is commonly available in 25 kg bags or drums suited to bulk industrial procurement. This ensures safe handling and stability during transport and long-term storage in warehouse facilities.