Overview
Sodium hydrosulfide ( CAS 16721-80-5 ), also known as sodium sulfhydrate and commonly abbreviated as NaHS, is an inorganic sulfide salt used across heavy industry as a reactive sulfur source and chemical intermediate.
It functions primarily as a reducing agent, precipitant, and flotation reagent in processes where controlled sulfide chemistry is required. In mining and metals processing, NaHS is used as a selective flotation depressant.
It acts as a metal sulfide precipitant to recover copper, zinc, and other non-ferrous metals from ore slurries. Pulp and paper manufacturers use it in kraft cooking liquor to improve pulping efficiency and delignification rates.
Leather processors apply it as a depilatory agent to remove hair from hides during the beamhouse stage, a step critical to tannery throughput. In wastewater treatment, it precipitates heavy metals from industrial effluent streams.
This process creates insoluble sulfides, supporting compliance with discharge limits. Sodium hydrosulfide is supplied as an aqueous solution, typically at concentrations around 45% NaHS, and in solid flake form.
Technical grade is the standard commercial specification across most industrial applications. Solution grades are common for continuous-process industries due to handling and dosing convenience.
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Physical Properties
| Melting Point | 350 °C |
| Density | 1.79 g/cm³ |
| Flash Point | 90°C |
| Appearance | white crystals or powder with a very unpleasant smell |
| Color | Off-white |
| Form | Solid |
| Water Solubility | 620 g/L (20 ºC) |
Safety & Handling
Danger GHS02 GHS05 GHS06 GHS09 GHS07 GHS08 Hazard Statements H226 Flammable liquid and vapor H251 Self-heating; may catch fire H290 May be corrosive to metals H301 Toxic if swallowed H312 Harmful in contact with skin H314 Causes severe skin burns and eye damage H318 Causes serious eye damage H335 May cause respiratory irritation H371 May cause damage to organs H400 Very toxic to aquatic life Precautionary Statements P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking. P233 Keep container tightly closed. P234 Keep only in original packaging. P235 Keep cool. P240 Ground and bond container and receiving equipment. P241 Use explosion-proof [electrical/ventilating/lighting/…] equipment. P242 Use non-sparking tools. P243 Take action to prevent static discharges. P260 Do not breathe dust/fume/gas/mist/vapours/spray. P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P271 Use only outdoors or in a well-ventilated area. P273 Avoid release to the environment. P280 Wear protective gloves/protective clothing/eye protection/face protection. P316 Get emergency medical help immediately. P317 Get emergency medical help. P319 Get medical advice/attention if you feel unwell. P321 Specific treatment (see … on this label). P330 Rinse mouth. P363 Wash contaminated clothing before reuse. P390 Absorb spillage to prevent material damage. P391 Collect spillage. P405 Store locked up. P406 Store in a corrosion-resistant/… container with a resistant inner liner. P407 Maintain air gap between stacks/pallets. P410 Protect from sunlight. P413 Store bulk masses greater than … kg/… lbs at temperatures not exceeding … °C/…°F. P420 Store away from other materials. P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P301+P316 Get emergency medical help immediately. P302+P352 IF ON SKIN: Wash with plenty of water. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing. P308+P316 Get emergency medical help immediately. P362+P364 Take off contaminated clothing and wash it before reuse. P370+P378 Use … for extinction. P403+P233 Store in a well-ventilated place. Keep container tightly closed. P403+P235 Store in a well-ventilated place. Keep cool. P301+P330+P331 Rinse mouth. Do NOT induce vomiting. P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Rinse skin with water/shower. P303+P361+P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water/shower. P305+P354+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Other Names
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Chemical Properties
- CAS Number
- 16721-80-5
- EC Number
- 240-778-0
- Mol. Weight
- 56.07
- Category
- Flame Retardants