What are the application scenarios of sodium sulfide?
- Leather: Key Pre-treatment Auxiliary
As mentioned earlier, sodium sulfide is a core chemical in leather processing, mainly used for:
Furring Process: By the disulfide bonds in hair, it causes the hair to separate from the hide, while decomposing the hair follicle tissue, achieving efficient fur removal. It is for the pre-treatment of various leathers such as cattle, sheep, and pig skins.
Pickling Softening: Used in combination with lime, etc., to the alkalinity of the solution, dissolve non-collagen proteins in the hide (such as fat, intercellular material), soften the hide, and lay a foundation for tanning.
Decontamination Cleaning: Removes impurities such as oil stains and bloodstains on the surface of the hide, improving the cleanliness of the leather
- Metallurgy and Metal Processing: Purification and Treatment
Ore Flotation: In the selection of non-ferrous metals (such as copper,, zinc), sodium sulfide acts as a sulfidizer, which can convert the surface of non-sulfide minerals into a sulfide film, making it easy to with collectors to achieve the separation of ore and vein rock, and improve the efficiency of ore selection.
Metal Purification: Used in the wet refining of precious metals ( as gold, silver), it can precipitate metal ions from solution through reduction reactions, or remove impurity metals (such as iron, arsenic) from ore.
Surface Treatment: In the electroplating industry, sodium sulfide can be used to remove the oxide film on the metal surface, or to prepare black metal sulfide electroplating, enhance the corrosion resistance of the metal; it can also be used for desulphurization treatment of steel, to improve the performance of steel.
- Chemical and Pharmacy: Synthesis and Reaction
Chemical raw material synthesis: As a source of sulfur, it is used in the production of sodium thiosulfate, sodiumite, sulfide dyes (such as sulfide black, sulfide blue), sulfonamide drug intermediates, etc. For example, sodium sulfide reacts with-nitrochlorobenzene to generate p-nitroaniline, which is an important dye and pharmaceutical intermediate.
Organic synthesis reaction: In organic chemistry, is used for reduction reactions (such as the reduction of nitro to amino), cyclization reactions, etc., and participates in the preparation of organic compounds containing sulfur ( as thioether, thiol).
Waste water treatment: In industrial wastewater treatment, sodium sulfide can react with heavy metal ions (such as mercury, cadium, lead, copper) to form insoluble sulfide precipitates, thereby removing heavy metal pollution from wastewater. It is especially suitable for wastewater treatment in mining,plating, chemical and other industries.
- Paper Making and Textile: Pulping and Dyeing
Paper making pulping: In the cooking process of pulp, sodium sulfide can be used as a lignin remover, in combination with sodium hydroxide (constituting the sulfite pulping method), to destroy lignin structure in wood, separate fibers, and produce high-strength pulp.
Textile dyeing: Used in the preparation and dyeing process of sulfide d. Sulfide dyes need to be dissolved in an alkaline reducing solution of sodium sulfide to form a hidden color body, which can then be dyed on fibers, then restored to insoluble dyes through oxidation, forming a firm color, suitable for the dyeing of cellulose fibers such as cotton and hemp.
- Other fields:
Water treatment: Besides removing heavy metal, sodium sulfide with high content (such as 1500ppm grade) can be used to remove certain organic matter and suspended impurities in water, which assists in purifying water quality.
riculture: It is used in small amounts to prepare fungicides and insecticides, or as a soil modifier to regulate soil acidity and alkalinity (but the dosage needs be strictly controlled to avoid excessive sulfur harming crops).
Laboratory use: As a chemical reagent, it is used for qualitative and quantitative analysis in analytical chemistry ( as detecting heavy metal ions), or as a reducing agent to participate in various experimental reactions.
Application precautions
Sodium sulfide has strong corrosiveness and toxicity, and aqueous solution is prone to release toxic hydrogen sulfide gas. Protective measures (such as wearing gas masks and alkali-resistant gloves) should be taken during operation, it should be carried out in a well-ventilated environment.
Waste liquid containing sodium sulfide needs to be treated (such as oxidized into sulfate) to meet standard before discharge, to avoid polluting the environment and harming the ecology.