A reducing agent commonly used in dyeing is sodium hydrosulfite
Sodium Hydrosulfite Market

When sodium dithionite is exposed to air, it breaks down quickly. The solid form releases sulphur gases that are corrosive to machinery and structures when it comes into contact with water. A nitrogen pad is typically used to store the aqueous solution in closed tanks. The most common form of sodium dithionite delivery is dry powder. Sodium Hydrosulfite commercial products might include stabilizers, chelates, and buffers (phosphates, carbonates).

Because sodium hydrosulfite is a potent reducing agent and can successfully react with the dyes in the pulp, it is also very effective at bleaching recycled pulp. Additionally, the majority of recycled furnishings typically include some mechanical pulps that can be bleached with sodium hydrosulfite. The sodium hydrosulfite bleaching conditions for mechanical pulps and recycled pulp are very similar.

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