Sodium thiosulfate
Sodium thiosulfate
Sodium thiosulfate, also known as sodium subsulfite, sodium soda, and sea wave, is a common thiosulfate with the chemical formula Na2S2O3. It is a product in which an oxygen atom in sodium sulfate is replaced by a sulfur atom. Therefore, the oxidation number of the two sulfur atoms is are -2 and +6 respectively.
There are many synthesis methods for sodium thiosulfate, including sodium sulfite method, alkali sulfide method, etc.
1. Sodium sulfite method: react soda ash solution with sulfur dioxide gas, add caustic soda to neutralize, add alkali sulfide to remove impurities, filter, then dissolve sulfur powder in hot sodium sulfite solution for reaction, filter, remove impurities, filter again, and add caustic soda After alkali treatment, concentration, filtration, crystallization, centrifugal dehydration and screening, the finished product of sodium thiosulfate is obtained.
2. Alkali sulfide method: The raw material liquid prepared from the alkali sulfide evaporation residue and barium sulfide wastewater (containing sodium carbonate and sodium sulfide) reacts with sulfur dioxide. After clarification, sulfur powder is added for heating reaction, followed by evaporation, cooling and crystallization, washing and separation. , screening to obtain the finished product of sodium thiosulfate.
3. The raw material used to prepare anhydrous sodium thiosulfate is sodium thiosulfate pentahydrate. The pure sodium thiosulfate pentahydrate crystals are heated to dissolve them all in its own crystal water, and heated and concentrated below 100°C. When a large amount of anhydrous crystals precipitate, the crystals are separated and dried below 100°C.
4. Use dehydration method: The sodium thiosulfate pentahydrate crystal is heated indirectly with steam to dissolve it in its own crystal water. After concentration, centrifugal dehydration, drying and screening, the finished product of anhydrous sodium thiosulfate is obtained.
5. Comprehensive method: The main ingredients are sodium sulfide, sodium sulfite, sulfur and a small amount of sodium hydroxide. The finished product is obtained after vacuum evaporation, activated carbon decolorization, filter press, cooling, crystallization, centrifugal dehydration and screening of the material liquid.
6. Sodium sulfate neutralization method: waste materials whose main components are sodium sulfide and a small amount of sodium carbonate.
