Sodium Hydrosulfide (NaHS) 16721-80-5

Sodium Hydrosulfide (NaHS), also known as sodium bisulfide or sodium hydrogen sulfide, is a colorless to light yellow crystalline solid with the formula NaHS and a molecular weight of 56.07 g/mol. It is highly soluble in water and alcohol, with its aqueous solution being strongly alkaline. The 70% grade in yellow flake form is the most common commercial product .

Sodium Hydrosulfide is primarily used in copper mining as a flotation agent for ore beneficiation, in the leather industry for dehairing hides and tanning, in paper manufacturing as a makeup chemical for the Kraft process, in the production of sulfur-containing dyes, for rayon and cellophane desulfurizing, and as a raw material for manufacturing ammonium sulfide and pesticide intermediates .

In copper mining, Sodium Hydrosulfide serves as a sulfidizing agent in froth flotation to improve the recovery of oxide copper minerals. It reacts with oxidized mineral surfaces to form a sulfide layer, allowing conventional sulfide collectors to attach and float the copper minerals. NaHS in solution has lower alkalinity than sodium sulfide, making it more cost-effective for large-scale mining operations .

In the leather industry, Sodium Hydrosulfide is a key chemical for unhairing (dehairing) hides. It works by breaking down the keratin protein in hair, allowing for efficient removal without damaging the hide. It is often used in combination with lime in the liming process. NaHS is preferred for its effectiveness and relatively lower alkalinity compared to sodium sulfide .

Sodium Hydrosulfide requires careful handling. It is corrosive to skin and metals, and reacts with acids to release toxic and flammable hydrogen sulfide gas. Solutions should be kept strongly alkaline (pH > 10) to minimize H₂S release. Store in a cool, dry, well-ventilated area in tightly sealed containers, away from moisture and acids. Use appropriate PPE including gloves, goggles, and respiratory protection. The product is moisture-sensitive and hygroscopic — protect from humidity .