Food grade Potassium pyrophosphate CAS:7320-34-5

What is Potassium pyrophosphate (CAS 7320-34-5)?

Potassium pyrophosphate (tetrapotassium pyrophosphate, TKPP) is a potassium salt of pyrophosphate. It is a member of the condensed phosphate (polyphosphate) family and is generally represented by the chemical formula:

K4P2O7 (CAS No. : 7320-34-5, molecular weight approx. 330.34)

It is white powder or lumpy solid at normal temperature, slightly hygroscopic, relative density 2.534, melting point about 1109℃. Potassium pyrophosphate is freely soluble in water (about 187 grams dissolves in 100 grams of water at 25°C), insoluble in ethanol, and its aqueous solution is alkaline (a 1% aqueous solution has a pH of about 10.2).

Potassium pyrophosphate are one of the four potassium ions ( K + ) and one of the pyrophosphate ions ( P 2 O 7 4- ) . About the molecular framework. The pyrophosphate ion is produced by the dehydration and condensation of two phosphate ions. Pyrophosphate can chelate calcium, magnesium and heavy metal ions, and forms stable complexes with calcium and magnesium ions in hard water. It also has a good dispersibility, buffering and emulsifying properties, this multi-faceted ability of “chelation + dispersion + buffering” is the core basis of its wide application in many fields such as electroplating, detergent, ceramics, food.

Potassium pyrophosphate is a condensed phosphate and has the usual chemical properties of condensed phosphates. It is alkaline in aqueous solution, can chelate alkaline earth metal and heavy metal ions, and is readily decomposed on heating (on prolonged boiling it hydrolyzes to phosphates). It has better solubility and chelating ability than sodium pyrophosphate. Store in a dry, sealed container.

Industrial-grade potassium pyrophosphate refers to the products mainly used in industrial production, the main content is generally more than 95% (electroplating grade should be stricter). Industrial-grade products pay more attention to the following indicators than food-grade and reagent-grade products:

Primary content

The purity is directly related to the electroplating complexing ability and the washing and dispersing effect, and the electroplating grade has higher requirements.

Arsenic, iron and heavy metals limits

Electroplating solutions are sensitive to metal impurities like iron. The content of these impurities affects the quality of the plating layer and the safety of the product, and must be strictly controlled.

Matter insoluble in water

In electroplating and cleaning solutions, water-insoluble substances can form suspended solids, which influence the results of the process and should be kept low.

pH & Alkalinity

The aqueous solution is alkaline pH stability affects the buffering and chelating properties so it should be within specifications.

Moisture

Potassium pyrophosphate is slightly hygroscopic , and excessive moisture content will affect the stability of measurement and storage , which needs to be controlled and sealed in packaging .

What are the uses of industrial-grade Potassium pyrophosphate?

1.Electroplating industry (core application)

Potassium pyrophosphate is the key complexing agent for cyanide-free electroplating of pyrophosphates. It can replace highly toxic sodium cyanide in electroplating. It forms stable complexes with metal ions such as copper, zinc and tin, thus improving the conductivity of the plating solution and the cathodic polarization and improving the quality of the plating layer. It is widely used in cyanide free copper plating, zinc plating, tin plating and pretreatment processes for electroplating, and it is an important raw material for environmentally friendly electroplating.

2.Detergents and cleaning agents

Potassium pyrophosphate is used as a detergent builder, water softener and buffer. It chelates calcium and magnesium ions in hard water. It increases detergency of surfactants. It is very popular in the formulation of high-class laundry powders, liquid detergents and dishwashing detergents.

3.Industrial and boiler descaling cleaning

Potassium pyrophosphate is used in formulating metal surface cleaners, bottle cleaners and boiler descaling agents. It chelates and disperses oxides, scale and stains on surfaces of metals. It is used for cleaning food and beverage bottles and cans, and for cleaning industrial equipment.

4.Ceramic and Coatings

Potassium pyrophosphate is used in the ceramics industry as a clay dispersant to improve the fluidity of ceramic slurries. Potassium pyrophosphate is also used as a dispersant and buffer for pigments and dyes to help pigments in coatings and paints disperse evenly and stabilize the system.

5.Water Processing

Potassium pyrophosphate is used as a water softener, scale inhibitor and buffer in water treatment. It ties up the calcium and magnesium ions in the water to stop scale from forming. It is used in water recirculation systems and in industrial water treatment.

6.Food sector

Food grade potassium pyrophosphate is used as an emulsifier, chelating agent and texture modifier to help meat products hold water and improve texture. It is also used to stabilize beverages and dairy products. The amount used shall be in accordance with standards for the use of food additives.

7.Paints and coatings

Potassium pyrophosphate is used as a dispersant and buffer for pigments and dyes. It helps to disperse pigments evenly and to stabilize coatings. It can indirectly participate in the production of home decoration coatings and paints.

8.Additional Use Cases

The application fields are constantly expanding, such as reagents for removing iron ions in printing and dyeing, clay thinners in drilling mud, buffers in automotive cooling systems, and buffers in fabric treatment.

Summary

Potassium pyrophosphate (Tetrapotassium Pyrophosphate, TKPP) White powdery condensed phosphate. Easily soluble in water, giving an alkaline aqueous solution. It has a number of functions such as chelation, dispersion and buffering. In everyday life we meet it indirectly in the electroplating of hardware and electronics, detergents, food, ceramic tiles, coatings and water treatment. Industrial-grade potassium pyrophosphate is widely used in industry as cyanide-free electroplating complexing agent (core component), detergent additive, industrial cleaning and boiler descaling agent, ceramic coating dispersant, water softener scale inhibitor and food emulsifying chelating agent. It is an important phosphate chemical connecting “daily necessities” with “electroplating, daily chemicals, ceramics and food”.