CAS number: 1313-82-2 

Molecular Weight: 78.04 

Water Solubility: 186 g/L (20 ºC) 

Specific Gravity: 1.856 

Melting Point: 950 °C(lit.) 

Density: 1.86 g/mL at 25 °C(lit.) 

Storage Conditions: Refrigerator (+4°C) 

Solubility: 186 g/L (20 ºC) 

Morphology: Yellow or red flake

Color: Yellow or red depends on Fe content

Stability: It is prone to spontaneous combustion. Incompatible with acids, metals, and oxidizers. When it comes into contact with acids, it releases toxic gases. Fine dust/air mixtures are explosive. It is hygroscopic.

Applications 

The traditional and emerging uses of sodium sulfide are extensive, detailed below:

1. Mining Applications:

In mining, sodium sulfide is not only used in the flotation process to extract metals (such as copper, lead, zinc, etc.) but also in the extraction and refining of precious metals like gold and silver. Sodium sulfide reacts with metals to form insoluble sulfides, enabling the separation and purification of metals.

2. Wastewater Treatment

Sodium sulfide plays a crucial role in water treatment, especially in removing heavy metal ions from water. It reacts with heavy metals in water to form insoluble sulfide precipitates, thereby purifying the water. Additionally, sodium sulfide is used in treating cyanide-containing wastewater, converting cyanides into relatively harmless sulfides.

3. Chemical Manufacturing

In chemical manufacturing, sodium sulfide is an important raw material for synthesizing various sulfides and sulfates. For example, it is used in the production of sulfur dyes, vulcanization accelerators, and vulcanized rubber. Sodium sulfide is also used in the production of dimethyl sulfoxide (DMSO), an important industrial solvent and anti-inflammatory medication.

4. Agricultural Use

In agriculture, sodium sulfide is used as a soil amendment to adjust soil pH and increase soil sulfur content, aiding crop growth. Sodium sulfide also helps in controlling plant diseases, such as rice blast.

5. Pharmaceuticals and Healthcare

In the pharmaceutical industry, sodium sulfide is used in the synthesis of certain drugs. In healthcare, sodium sulfide has been used as an ingredient in medicated creams for skin diseases, but due to its toxicity and corrosiveness, its use has significantly decreased.

6. Photography and Printing

In photography, sodium sulfide was used in the fixing process of black and white photos as a fixer, dissolving unexposed silver salts. In printing, sodium sulfide is used in certain special treatments during plate making.

7. Leather Industry

In the leather industry, sodium sulfide is utilized in the dehairing process, effectively removing hair from animal hides while causing minimal damage to the leather itself.

8. Textile Industry

In the textile industry, sodium sulfide is used in the desulfurization process of fabrics, removing sulfur from the fabrics, reducing damage, and improving fabric quality.

9. Pulp Production

In pulp production, sodium sulfide serves as a cooking agent, helping to release fibers from wood to produce paper.

10. Personal Care

In certain personal care products, sodium sulfide was used in formulations for dandruff treatment in hair care products, but due to its irritancy and corrosiveness, its use has greatly diminished.

11. Laboratory Applications

In laboratories, sodium sulfide is used as an analytical reagent for detecting metal ions, measuring hydrogen sulfide, and properties. It is also used in educational experiments to demonstrate chemical reactions.

12. Food Processing

In some food processing operations, sodium sulfide was used as a preservative, but due to its toxicity, it has been replaced by safer preservatives.

13. Fertilizer Production

Sodium sulfide is used in the production of certain types of fertilizers, such as ammonium sulfate, which are rich in sulfur and beneficial to crop growth.

14. Electronics Industry

In the electronics industry, sodium sulfide is used in the manufacture of semiconductor materials and photovoltaic materials, such as cadmium sulfide.

15. Plastics Industry

In the plastics industry, sodium sulfide is added to certain plastic products to improve their performance.

16. Metallurgical Industry

In the metallurgical industry, sodium sulfide is used in the surface treatment of metals, such as the sulfidation treatment of steel to enhance its corrosion and wear resistance.

17. Oil and Gas Extraction

In oil and gas extraction, sodium sulfide is used to treat oilfield water containing hydrogen sulfide, preventing corrosion of equipment by hydrogen sulfide.

18. Flame Retardants

Sodium sulfide is used as a raw material in the production of certain flame retardants, improving the flame resistance of materials.

19. Glass Industry

In the glass industry, sodium sulfide is used in the manufacture of special types of glass, such as colored glass.

20. Coatings Industry

In the coatings industry, sodium sulfide is used in the production of certain types of pigments and coating additives.

21. Cosmetic Industry

In the cosmetic industry, sodium sulfide was used in hair coloring products, but due to its potential hazards, its use has significantly decreased.

22. Cleaning Agents

In some industrial and household cleaning agents, sodium sulfide is used as a decontaminant, especially effective against grease and stains.

23. Waste Treatment

Sodium sulfide is used in waste treatment for stabilizing harmful waste, such as mercury-containing waste.

24. Biological Experiments

In biological experiments, sodium sulfide is used in the preparation of microbial culture media and as an enzyme activity inhibitor.

25. Educational Research

In educational research, sodium sulfide is used to demonstrate chemical reactions and properties, as well as a material for chemical teaching experiments.

26. Agricultural Research

In agricultural research, sodium sulfide is used to study the sulfur cycle and metabolism in soil and plants.

27. Environmental Monitoring

In environmental monitoring, sodium sulfide is used to monitor the sulfide content in the atmosphere and water bodies to assess environmental pollution levels.

28. Food Inspection

In food inspection, sodium sulfide is used to detect sulfur and sulfide content in food, ensuring food safety.

29. Pharmacological Research

In pharmacological research, sodium sulfide is used to study the effects of drugs on cells and tissues, as well as a intermediate in drug synthesis.

30. Toxicology Research

In toxicology research, sodium sulfide is used to study its toxicity and mechanisms of poisoning, as well as methods of detoxification.

31. Occupational Health Research

In occupational health research, sodium sulfide is used to study the health effects of workers exposed to sodium sulfide in the workplace and to develop corresponding protective measures.

Hazards Information

Sodium Sulfide has the following hazards:

1. Corrosiveness: Its aqueous solution is corrosive, can cause serious chemical burns.

2. Irritation: Dust and solutions are strongly irritating to the eyes and respiratory tract.

3. Toxicity: Intake or inhalation of sodium sulfide can lead to poisoning, and it can be fatal in severe cases.

4. Environmental hazards: Highly toxic to aquatic organisms, releasing into the environment may have long-term adverse effects on the ecosystem.

5. Combustibility: Although not inherently flammable, the hydrogen sulfide gas produced when reacting with acids is flammable, and it may form an explosive mixture in the air.

6. Reactivity: Reacts violently with acids, oxidizers, and many metal salts, which may lead to fires or explosions.

Safety Measures:

Due to the hazards of sodium sulfide, the following safety measures need to be taken when handling it:

- Operate in well-ventilated environments.

- Wear appropriate personal protective equipment, such as chemical gloves, goggles, and protective clothing.

- Avoid mixing with acids, oxidizers, and metal salts.

- Store in a cool, dry, well-ventilated place, away from sources of fire and heat.

- Follow local safety and environmental protection regulations, and dispose of waste properly.

Emergency Handling:

- Skin contact: Wash immediately with plenty of water, then seek medical attention.

- Eye contact: Rinse thoroughly with water for at least 15 minutes, and seek medical attention immediately.

- Inhalation: Move to fresh air immediately, maintain breathing通畅， and if necessary, perform artificial respiration, then seek medical attention promptly.

- Ingestion: Do not induce vomiting; seek medical attention immediately.

Waste Disposal:

The disposal of sodium sulfide waste should follow local environmental regulations, usually requiring professional chemical waste disposal companies to prevent harm to the environment and human health.

Environmental Impact

The environmental impact of sodium sulfide mainly stems from its strong alkalinity and toxicity. It is highly toxic to aquatic organisms, and its release into the environment can cause long-term adverse effects on ecosystems. Therefore, waste sodium sulfide needs to be disposed of by professional chemical waste treatment companies to prevent harm to the environment and human health[^1^].

Toxicological Information

Sodium sulfide possesses certain toxicity; ingestion or inhalation of sodium sulfide can lead to poisoning, which can be fatal in severe cases. Prolonged exposure to sodium sulfide may cause irritation or burns to the skin and eyes. It can decompose into hydrogen sulfide in the gastrointestinal tract, causing hydrogen sulfide poisoning after oral administration. It is corrosive to the skin and eyes. Therefore, strict adherence to safety procedures, wearing appropriate personal protective equipment, and ensuring good ventilation in the workplace are essential during handling[^5^].

Emergency Response to Spills

In the event of a spill, the contaminated area should be immediately isolated, and warning signs set up around it. Emergency responders should wear gas masks and chemical protective suits. Do not come into direct contact with the spilled material to avoid raising dust. Collect it with a clean shovel into a dry, covered container and transport it to a waste disposal site. Alternatively, it can be rinsed with plenty of water, and the diluted wash water can be discharged into the wastewater system. In cases of large spills, collect, recycle, or dispose of it safely.

Hazard Classification of Sodium Sulfide in Various Countries

China

In China, sodium sulfide is listed in the "Catalogue of Hazardous Chemicals" (2015 Edition), falling under danger class 8, which is categorized as corrosive substances. According to the "Classification and Labeling of Dangerous Goods" (GB 6944-2012), sodium sulfide is classified as a class 8 corrosive material, with the hazard goods number 82010.

United States

In the United States, the Pipeline and Hazardous Materials Safety Administration (PHMSA) regulates sodium sulfide. It is classified as a corrosive solid and must follow specific transportation regulations, including packaging, labeling, and transportation methods.

European Union

Within the European Union, sodium sulfide is classified as a substance with severe corrosive properties under the CLP (Classification, Labelling and Packaging) regulation, belonging to danger category 8. Additionally, it must be transported following the United Nations Recommendations on the Transport of Dangerous Goods.

Japan

In Japan, sodium sulfide is managed according to the "Chemical Substances Control Law," requiring companies to assess chemicals for potential risks to human health and the environment. Sodium sulfide is considered a harmful substance.

International Maritime Transport

For international maritime transport, sodium sulfide is classified as a class 8 corrosive substance according to the International Maritime Organization's (IMO) "International Maritime Dangerous Goods Code" (IMDG Code), and special packaging and transportation regulations must be adhered to.

Preparation Methods

There are several methods for preparing sodium sulfide, including the coal powder reduction method, absorption method, barium sulfide method, and gas reduction method. The coal powder reduction method involves mixing mirabilite with coal powder in a certain ratio and calcining it at high temperatures of 800-1100℃. The product is then dissolved into a liquid using dilute alkali solution while hot, left to settle, and the concentrated alkali solution from the top is evaporated to obtain solid sodium sulfide. The absorption method uses a 380-420g/L sodium hydroxide solution to absorb hydrogen sulfide waste gas containing more than 85% H2S, and the resulting product is evaporated and concentrated to produce finished sodium sulfide. The barium sulfide method involves producing sodium sulfide as a byproduct during the double decomposition reaction of sodium sulfate and barium sulfide to precipitate barium sulfate. The gas reduction method, in the presence of an iron catalyst, reacts hydrogen (or carbon monoxide, producer gas, methane) with sodium sulfate in a fluidized bed to produce high-quality anhydrous granular sodium sulfide (containing 95%-97% Na2S). 

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