Sodium Tripolyphosphate (STPP) is a sodium salt of the pentabasic form of polyphosphate. It is commonly used as a sequestering agent in detergents and cleaners, as a preservative in food and beverages, and in various industrial processes.

The name describes the structure of the molecule:

• Sodium is a chemical element, known for its role in various compounds, especially table salt (sodium chloride). In chemistry, sodium is often used for its osmoregulation and ion-balancing properties.
• Tripolyphosphate is a phosphate salt, characterized by three phosphate units linked together. It is commonly used in industrial and food applications as a preservative, emulsifier, and to improve the texture of food products, particularly in seafood and processed meats.

Raw Materials Used in the Production

Rock Phosphate. The primary source of phosphorus, processed to produce phosphoric acid.

Sulfuric Acid. Used to extract phosphoric acid from rock phosphate.

Caustic Soda. Reacts with phosphoric acid to form STPP.

Water. Used as a solvent and to adjust the solution's concentration.

Industrial Chemical Synthesis of Sodium Tripolyphosphate

• Preparation. The mixture is prepared by combining phosphoric acid and caustic soda in water.
• Reaction. The mixture reacts to form STPP and water.
• Crystallization. STPP crystallizes out of the solution.
• Separation. The STPP crystals are separated from the solution.
• Drying. The STPP crystals are dried to remove excess water.

Appearance and Color. 

STPP appears as a white crystalline or yellowish powder.

Commercial applications:

Detergent Industry. STPP is commonly used as a bleaching and water softening agent in laundry detergents and dishwasher detergents. It helps enhance the effectiveness of detergents by removing calcium and magnesium ions from water.

Food Industry. Used as a preservative and to improve texture in some food products, like frozen seafood and processed meats.

Water Treatment. Used in water treatment to prevent scale formation and to control corrosion in pipes.

Safety. 

While STPP is generally considered safe in small amounts, there are concerns about its environmental impact due to eutrophication in water bodies. Its safety in food use may depend on the amount and frequency of consumption.