Tetrapotassium Pyrophosphate (TKPP)

What is Tetrapotassium Pyrophosphate (TKPP)?

Molecular Formula (Tetrapotassium Pyrophosphate (TKPP)): K₄P₂O₇

Molecular Weight: 330.334 g/mol

Chemical Name: Potassium Pyrophosphate

CAS Number: 7320-34-5

TKPP has all the properties of another polymeric pyrophosphate, Tetrasodium Pyrophosphate (TSPP). It can be considered identical to Tetrasodium Pyrophosphate (TSPP). However, it has higher solubility. It can also undergo chelation reactions with metal ions, including alkaline earth and heavy metal ions.

Tetrakal helps to soften hard water by forming a complex structure with the Mg⁺² and Ca⁺² ions present. This increases the water's effectiveness during washing and helps remove dirt.

The pyrophosphate ion ((P₂O₇)^-4) in Tetrakal has a very strong dispersing capability on fine and scattered solid molecules. This property allows for the homogeneous mixing of trace and fine substances.

Tetrapotassium Pyrophosphate  E-Number: E 450

Other Names Include;

• Potassium Pyrophosphate
• 7320-34-5
• TKPP
• Tetrapotassium Diphosphate
• Diphosphoric Acid, Potassium Salt
• Tetrapotassium Diphosphorus
• Pyrophosphoric Acid, Tetrapotassium Salt
• Tetrapotassium Phosphonato Phosphate
• Potassiumpyrophosphate
• Potassium diphosphate tetrabasic
• Potassium Pyrophosphate anhydrous
• Tetrapotassium ion diphosphate
• Potassium diphosphate, 98% extra pure
• Tetrakal

How is it produced?

The production of Tetrakal can be described using neutralization and calcination methods.

The chemical inputs in the Tetrapotassium Pyrophosphate (TKPP) production process are 1 mole of food-grade 85% Phosphoric Acid and 2 moles of food-grade Potassium Hydroxide.

In the production process of Tetrapotassium Pyrophosphate (TKPP), 30% food-grade phosphoric acid is added and mixed slowly. During this time, food-grade Potassium Hydroxide is added. An appropriate neutralizing solution is added to maintain the pH at a constant 8.4. After the reaction in this production stage is complete, the solution is heated.

A color change occurs at this point. Activated carbon is added during this production stage for color removal. In the next step, to remove insoluble substances, the filtered and clarified filtrate is heated to 100-125 °C to reach the desired concentration in the evaporator.

In the Tetrapotassium Pyrophosphate production process, cooling is carried out after precipitation. After cooling, it will separate at temperatures below 20 °C.

During the production of Tetrapotassium Pyrophosphate (TKPP), the mixture is centrifuged to separate and obtain di-potassium phosphate trihydrate, and then heated to a temperature of 120-130 °C to remove the crystal water, forming anhydrous di-potassium hydrogen phosphate.

The next step in the Tetrapotassium Pyrophosphate (TKPP) production process is polymerization. The material is transferred to a calciner to be calcined at a temperature of 500-600 °C. After this process, upon cooling, Potassium Pyrophosphate is obtained.

The reaction process for these steps is as follows;

H₃PO₄ + 2KOH  》K₂HPO₄ + 2H₂O

2 K₂HPO₄[Delta] 》K₄P₂O₇ + H₂O

What are its Physical and Chemical Properties?

At room temperature, it exists as a white crystalline powder or granules. It has a very strong ability to absorb/retain moisture from the air. Tetrapotassium Pyrophosphate (TKPP) is a very hygroscopic chemical.

Regarding solubility, it is readily soluble in water but insoluble in ethanol. Its aqueous solution is alkaline.

The pH of a 1% aqueous solution of Tetrapotassium Pyrophosphate (TKPP) is approximately 10.5. This indicates that it is a basic chemical.

The solubility of TKPP has been determined to be 187 g in 100 g of water at 25 °C. This property indicates that its solubility in water is excellent.

Melting point is 1090 °C.

Density: 2.33 g/cm³

Boiling Point: Not available

Solubility: Soluble in water.

How is Tetrapotassium Pyrophosphate (TKPP) Used in Toothpastes and What are its Effects?

Over time, dental calculus (tartar) forms on teeth. Pyrophosphate sources have begun to be used in the manufacturing of toothpastes to prevent the formation of supragingival dental calculus.

Pyrophosphate sources are included in formulations as tetrasodium pyrophosphate, tetrapotassium pyrophosphate, and disodium pyrophosphate.

Pyrophosphate has a strong affinity for hydroxyapatite surfaces, interacting with Ca⁺² ions in the hydration layer. By binding to Ca⁺² on the enamel surfaces, hydroxyapatite reduces the capacity for proteins to attach.

Tetrasodium pyrophosphate is added to toothpastes to prevent the formation of calcium phosphate on the teeth, thereby inhibiting the formation of a pellicle (film layer) in the mouth.

Studies in toothpaste production have found that fluoride provides better protection when applied with copolymers containing tetrasodium pyrophosphate.

What are the Usage Areas of Tetrapotassium Pyrophosphate (TKPP)?

• It is used with other phosphate chemicals as a binder in ham and sausage, also increasing their yield.
• In some industries, cyanide-free plating methods are preferred. It is used in such cyanide-free electroplating applications as a complexing agent.
• Phosphorus is vital for plants. It is an essential component in the formation of cells, the plant's energy source. It plays a role in producing nucleic acids, phospholipids, and some important coenzymes. It is an important compound for supplying the phosphorus that plants need.
• In the ceramics industry, Tetrakal is used as a clay dispersing agent.
• It is used as a high-temperature stabilizing salt in the production of oilfield treatment fluids. The main function of the formulation is its hydraulic fracturing properties.
• In coatings applied via electro-deposition, it is used together with potassium sodium tartrate.
• It is used to provide a source of Phosphorus (P) for some plants grown in calcareous soils.
• The canning of some natural seafood can cause struvite formation. Fish like salmon, shrimp, and mackerel are particularly prone to causing struvite. This is due to the magnesium ammonium phosphate compound secreted from seafood forming glass-like crystals. The amount of struvite can vary depending on the type of canned fish. Tetrapotassium pyrophosphate is used as a preservative during production to prevent struvite formation in canned fish and to prevent color deterioration in canned fruits.
• In ice cream production, a voluminous or 'puffy' texture is desired. This requires a substance with high hygroscopicity and solubility. Tetrapotassium Pyrophosphate is used to produce a more voluminous and airy ice cream.
• It is used to increase the bulk of raw coffee material.
• Tetrakal is used for its properties as a buffering agent, dispersing agent, protein modifier, coagulant, sequestrant, and mineral supplement.

What are Other Usage Areas?

• TKPP is used as a preservative to extend the shelf life of products by sequestering polyvalent cations that cause lipid oxidation and the development of rancidity.
• Certain challenges are faced in cheese production. Emulsifying salts affect the texture, pH, and melting properties of processed cheese. Tetrapotassium pyrophosphate is the chemical that helps buffer the cheese's pH and promotes emulsification by interacting with milk protein.
• It is used as a dispersant in the manufacture of drilling fluid additives. TKPP is used in industrial drilling applications, where it serves as a component in completion fluids.
• It is used as a food additive, where it functions as an emulsifier, texturizer, and thickener.
• In latex paints, it acts as a dispersing agent by forming stable, high-viscosity solutions. It aids in the wetting of pigments.
• Tetrakal is used as a coating and surface treatment agent. It provides a strong phosphating effect for the phosphate coating of metal surfaces.
• It is used in the manufacture of lubricants and lubricant additives.
• TKPP is used as a builder in cleaning agents for industrial equipment in the food industry (e.g., heat exchangers, air exhaust equipment).
• It is used in conjunction with Sodium Lauryl Sulfate to clean stains and dirt from fabrics and substrates.
• In the production of biodegradable, water-soluble plastics, it is one of the inorganic compounds used as a source of phosphorus.
• Due to its high solubility, it does not cause precipitation issues compared to orthophosphates. While other phosphate groups can cause precipitation problems at low temperatures, Tetrakal does not.

What Factors Affect its Price?

Tetrapotassium Pyrophosphate (TKPP) prices are directly dependent on the prices of the chemicals used in its production. As the price of Phosphoric Acid increases, the price of Tetrakal will increase. As the price of Potassium Hydroxide increases, the price of TKPP will increase.

The price of Tetrapotassium Pyrophosphate (TKPP) is directly related to its production facilities. As the number of production facilities increases, prices will temporarily decrease.

Tetrapotassium Pyrophosphate (TKPP) prices are directly dependent on the stock levels of the companies selling the chemical. The larger the stock held by companies selling Tetrapotassium Pyrophosphate (TKPP), the lower the price will be.

The price of Tetrapotassium Pyrophosphate (TKPP) also depends on the distance from the production facility. Prices will increase with distance from the production plant due to higher transportation costs.