Sodium tripolyphosphate (STPP), also known as triphosphoric acid or pentasodium salt, is an inorganic chemical with the formula Na5P3O10.
Of this compound, which is a five-anion salt, it is considered on a larger scale as a raw material for household and industrial products, including detergents. Sodium triphosphate is used as the main ingredient in detergents, cleaners, and soaps in various forms including gels, liquids, powders and washing machines, and dishwasher molds.
Many household cleaning products, including surface cleaners, cosmetics, contain sodium tripolyphosphate.
Physical and chemical properties:
Sodium tripolyphosphate is completely stable in the environment and is converted to pyrophosphate and phosphate at a temperature of 100 ° C. Its physical appearance is available in the form of granules and powder with 100 to 200 mesh. This compound has a pH of 9.4, which due to its high buffering properties, can easily remove acid stains.
|Molar mass||367.864 g/mol|
|pH||Between 9,1 and 10,2 (1 % solution)|
|Melting Point||622 °C (1,152 °F; 895 K)|
|Solubility in water||14.5 g/100 mL (25 °C)|
|Solubility||Insoluble in ethanol|
|Chemical Structure Depiction|
Sodium tripolyphosphate production process:
The raw materials for the production of sodium are triphosphate, sodium carbonate, and phosphoric acid. To produce it, first after combining sodium carbonate and phosphoric acid, two salts called monosodium phosphate and disodium phosphate are produced, and by combining these two salts together at a temperature of more than 300 ° C, sodium triphosphate is produced.
2 Na2HPO4 + NaH2PO4 → Na5P3O10 + 2 H2O
The second method is to use a wet process, the steps of which can be as follows
The reaction of phosphoric acid with a sodium compound and formation of a reaction mixture consisting of an aqueous solution of Na2HPO4 and NaH2PO4 with a pH above 6.
Heat the reaction mixture to a temperature in the range of 400 to 550 ° C and perform a crystallization step.
Heat the compound at a high temperature up to 700 ° C and then purify and finally produce a pure STPP product.
Applications and uses of sodium tripolyphosphate:
-One of the common applications of sodium tripolyphosphate is in detergents.
It has a great effect on detergents and in washing heavy metals in water such as calcium and magnesium, which causes the formation of insoluble metal salts, thus reducing the ability to wash or stop completely.
-This compound is used in food as a preservative.
-The use of this material, due to its effect in the removal of heavy metals, has an effective effect on water purification, and this property of phosphates, including sodium tripolyphosphate, has led to its use in the treatment of industrial effluents.
-The presence of small amounts of this material can enhance the flotation process of copper ore and be a cost-effective product with high efficiency in mining.
-It is used in the formulation of many health products, including mouthwashes, toothpaste, hair conditioners, shampoos, permanent and temporary hair dyes, and cosmetics and skincare products.
-In leather tanning, it is used as a covering agent, and synthetic tanning
-It is also used in the paper industry as an agent resistant to petroleum products during paper printing
-In the ceramic industry, this material is used as a factor to reduce the viscosity of the glaze and spread the clay evenly.
-Its use in the dyeing industry is also used as an effective factor in preserving dye and corrosion in textiles, rubber, fermentation, and antifreeze.
Sodium tripolyphosphate in detergents:
This compound is widely used in detergents and cleaners. It leads to the penetration of detergents into the fibers of clothes and other surfaces and by creating chelating with water hardening ions, it produces more bubbles and foam and also increases the dispersing property.
Due to its alkaline properties, it can help remove stains and also neutralize and soften the acid in water by neutralizing it.
As food additives:
This salt can cause freshness in meat and seafood and slow down the spoilage of these foods. This chemical helps maintain the natural color of meat and fish and improves their texture, which is done by retaining moisture in the food and slowing down their drying.
The vapors of this compound are toxic and can cause poisoning. also in case of contact with skin and eyes, it causes allergies and redness.
Excessive use of this combination leads to symptoms such as vomiting, headache, decreased urination, bloating and abdominal pain, dizziness, and irregular heartbeat.
People who deal with this substance need to use special glasses, masks, and work clothes.
Packing and storage:
Store in a cool, with proper ventilation, and keep away from incompatible substances.