Sodium sulfide

Sodium sulfide (Na₂S) is an inorganic compound commonly used in the chemical industry, pulp and paper industry, and in the production of rubber and leather. This compound appears as a solid, typically in the form of yellow to red crystals, although pure sodium sulfide is colorless. It is known for its distinctive rotten egg smell due to the release of hydrogen sulfide (H₂S) when it comes into contact with moisture.

Properties

Sodium sulfide is highly soluble in water, forming a strongly alkaline solution. It is also soluble in alcohol but insoluble in ether. The compound is a strong reducing agent and reacts with oxygen to form sodium sulfate (Na₂SO₄) and sodium sulfite (Na₂SO₃).

Production

Sodium sulfide is typically produced by the carbothermal reduction of sodium sulfate often using coal in a high temperature furnace. Another method involves the direct reaction of sodium with sulfur.

Applications

1. 1. 1. Leather Processing

In the leather industry, sodium sulfide is used in the liming process to remove hair and other keratinous substances from animal hides.

1. 1. 1. Pulp and Paper

In the pulp and paper industry, sodium sulfide is used in the Kraft process to break down the lignin bonding the cellulose fibers in wood.

1. 1. 1. Chemical Synthesis

Sodium sulfide is used as a reagent in the synthesis of organic compounds and in the manufacture of sulfur dyes and other chemical compounds.

1. 1. 1. Mining

It is also employed in ore processing as a part of the flotation process to enhance the non-ferrous metal recovery.

Safety

Sodium sulfide is corrosive and can cause severe skin burns and eye damage. It should be handled with appropriate safety measures, including protective clothing and eye protection. The compound also emits toxic fumes of sulfur compounds when heated to decomposition.

Environmental Impact

The use of sodium sulfide, particularly in industries like leather tanning and paper production, can lead to environmental concerns. It is crucial to manage waste containing sodium sulfide properly to prevent pollution and protect water quality.

See Also

• Sodium sulfate
• Sodium sulfite
• Hydrogen sulfide
• Sulfur dyes