Aluminium Phosphate: Properties, Structure, Applications, Health And Safety Hazards

Edited By Team Careers360 | Updated on Jul 02, 2025 05:14 PM IST

Aluminium phosphate is prepared by exposing a soluble aluminium salt to alkaline conditions and contains aluminium orthophosphate hydrate of the formula AlPO4.

Properties Of Aluminium Phosphate(AlPO4)

AlPO4 is the molecular formula for aluminium phosphate. AlPO4

has a molecular weight of 121.9529 g/mol. The melting point of aluminium phosphate is 1800°C. Aluminium phosphate has a density of 2.57 g/cm³. The pH of aluminium phosphate is between 3.0 and 7.5. The smell is rotten. It is a form of white crystalline powder. Its complexity is 36.8 and it is insoluble in water.

This Story also Contains

Properties Of Aluminium Phosphate(AlPO4)
Structure Of Aluminium Phosphate(AlPO4)
Aluminium Phosphate(AlPO4) Chemistry
Aluminium Phosphate(AlPO4) Applications
Aluminium Phosphate(AlPO4) Health And Safety Hazards

Aluminium Phosphate

Structure Of Aluminium Phosphate(AlPO4)

Aluminium phosphate generally exists as an anhydrous salt. However, its dihydrate and pentahydrate structures, represented as AlPO4.2H2O and AlPO4.5H2O, also occur. Aluminium phosphate compounds are formed by a phosphate anion and an aluminium cation. Its anhydrous salt structure is very similar to some other minerals such as quartz and has a trigonal crystal structure. However, its dihydrate has a structure similar to NaCl, with six cations coordinated with six anions.

Aluminium Phosphate(AlPO4) Chemistry

Aluminium phosphate reacts with hydrochloric acid to form phosphoric acid and aluminium trichloride.
Aluminium phosphate reacts with magnesium chloride and gives magnesium phosphate and aluminium trichloride as the product.

Aluminium Phosphate(AlPO4) Applications

Aluminium Phosphate tablets officially contain 500 mg per tablet of dry aluminium phosphate suitable for peppermint flavour.
Used as a beneficial antacid in patients experiencing significant loss of phosphate from aluminium salt.
Used in vaccine production as an additive to improve immunogenicity.
Aluminium phosphate carbonate gel was used in an aqueous suspension of hydroxy aluminium carbonate with orthophosphoric acid.
Due to its properties as a piezoelectric material, it is mainly used in the electronic and electrical industries.
It is also useful in making gums and adhesives. Additionally, it is the most commonly used antacid.
In industry it is used in ceramics, dental cements, cosmetics, paints, paper and pharmaceuticals.
Aluminium phosphate is the most common enhancer in vaccines, along with aluminium hydroxide.
Aluminium adjuvants are widely used with most antigens due to their low price and long history of efficacy. However, it is unclear how this salt acts as an adjuvant.
Aluminium phosphate is similar to aluminium hydroxide and is used to form AlCl3 to neutralise stomach acid (hydrochloric acid).
The gastrointestinal tract absorbs up to 20% of aluminium from ingested antacid salts – despite some unidentified concerns about the neurological effects of aluminium. It is said to be safe as an antacid under normal use, even during pregnancy and breastfeeding.
Aluminium phosphate can be used in combination or without other compounds that are white colourants such as pigments, corrosion inhibitors, cements and fillers.
Compound-related to it have similar uses. For example, Al(H2PO4)3 can be used in dental cements, metal coatings, glaze compositions, and refractory binders. Al(H2PO4)(HPO4), on the other hand, can be used in cements, adhesives and refractory binders.

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Aluminium Phosphate(AlPO4) Health And Safety Hazards

It is very dangerous from a health point of view.
It can cause irritation to skin and mucous membranes.
Coughing and wheezing can also be caused by its consumption.
Respiratory system is damaged due to it.
It is non-flammable.

Frequently Asked Questions (FAQs)

1. How does aluminium phosphate behave at high temperatures?

At high temperatures, aluminium phosphate exhibits excellent thermal stability. It maintains its structure and properties up to about 1500°C, making it useful in refractory materials and high-temperature applications.

2. What role does aluminium phosphate play in the production of detergents?

Aluminium phosphate is used as a builder in detergents. It helps to soften water by removing calcium and magnesium ions, which improves the cleaning efficiency of the detergent. It also helps to maintain the pH of the washing solution.

3. How is aluminium phosphate used in the field of catalysis?

In catalysis, aluminium phosphate is used as a solid acid catalyst and as a support for other catalysts. Its porous structure and acidic properties make it effective in various reactions, such as dehydration, isomerization, and cracking of hydrocarbons.

4. What makes aluminium phosphate useful in fire-resistant materials?

Aluminium phosphate is used in fire-resistant materials due to its high thermal stability and ability to form a protective layer when exposed to heat. When heated, it can release water and form a glassy barrier that insulates the underlying material from fire.

5. What is the significance of aluminium phosphate's amphoteric nature?

The amphoteric nature of aluminium phosphate means it can act as both an acid and a base, depending on the reaction conditions. This property makes it versatile in various applications, such as in catalysis, where it can participate in both acid-catalyzed and base-catalyzed reactions.

6. What is aluminium phosphate and how is it formed?

Aluminium phosphate is an inorganic compound with the chemical formula AlPO4. It is formed by the reaction between aluminium ions (Al3+) and phosphate ions (PO43-). This reaction typically occurs in aqueous solutions or through solid-state reactions at high temperatures.

7. How does the solubility of aluminium phosphate change with pH?

The solubility of aluminium phosphate is pH-dependent. It is generally insoluble in neutral conditions but becomes more soluble in both acidic and strongly basic environments due to its amphoteric nature.

8. How does the acidity of aluminium phosphate compare to other phosphates?

Aluminium phosphate is generally more acidic than other metal phosphates due to the high charge density of the Al3+ ion. This increased acidity affects its behavior in chemical reactions and its applications, particularly in catalysis and as a pH buffer.

9. What are the main industrial processes for producing aluminium phosphate?

Aluminium phosphate is typically produced by reacting aluminium hydroxide or aluminium oxide with phosphoric acid. It can also be synthesized by the reaction of aluminium salts with phosphate salts in aqueous solution, followed by precipitation and filtration.

10. How does the presence of aluminium phosphate affect soil chemistry?

In soil, aluminium phosphate can affect phosphorus availability to plants. It can form insoluble complexes with phosphate ions, potentially leading to phosphorus deficiency in plants. However, it can also act as a slow-release source of phosphorus under certain conditions.

11. What are the environmental implications of using aluminium phosphate in detergents?

While aluminium phosphate is less harmful than some other phosphates used in detergents, it can still contribute to eutrophication if released into water bodies. This has led to regulations limiting its use in some regions to protect aquatic ecosystems.

12. What are the potential health risks associated with exposure to aluminium phosphate?

While aluminium phosphate is generally considered safe, prolonged exposure to high levels can potentially lead to aluminium accumulation in the body. This has been associated with neurological effects, though the link is not fully established. Proper handling and protective measures are recommended in industrial settings.

13. How does aluminium phosphate compare to calcium phosphate in terms of biocompatibility?

Both aluminium phosphate and calcium phosphate are generally biocompatible, but calcium phosphate is more commonly used in biomedical applications due to its similarity to bone mineral. Aluminium phosphate is used in some dental applications but is less prevalent in other biomedical fields.

14. What is the role of aluminium phosphate in vaccine adjuvants?

Aluminium phosphate is used as an adjuvant in some vaccines. It helps to stimulate a stronger immune response to the vaccine by slowly releasing the antigen and attracting immune cells to the injection site.

15. What is the role of aluminium phosphate in water treatment?

In water treatment, aluminium phosphate is used as a flocculant. It helps to remove suspended particles and impurities from water by causing them to clump together, making them easier to filter out.

16. How does aluminium phosphate affect the properties of ceramics?

When added to ceramics, aluminium phosphate can improve their mechanical strength, thermal shock resistance, and chemical durability. It forms strong bonds within the ceramic matrix, enhancing its overall performance.

17. What is the significance of aluminium phosphate's low solubility product?

The low solubility product of aluminium phosphate means it forms a highly insoluble precipitate in aqueous solutions. This property is important in its applications in water treatment and in controlling phosphate levels in various systems.

18. How does the presence of aluminium phosphate affect the pH buffering capacity of soils?

Aluminium phosphate can act as a pH buffer in soils due to its amphoteric nature. It can help maintain a relatively stable pH by releasing or absorbing hydrogen ions, depending on the soil conditions.

19. How does aluminium phosphate contribute to dental cements?

In dental cements, aluminium phosphate is used for its ability to form strong bonds with tooth enamel and dentin. It also has biocompatible properties and can release fluoride ions, which help prevent tooth decay.

20. How does aluminium phosphate interact with proteins?

Aluminium phosphate can interact with proteins through electrostatic interactions and hydrogen bonding. This property is utilized in its role as a vaccine adjuvant, where it can adsorb protein antigens and present them to the immune system more effectively.

21. Why is the structure of aluminium phosphate important?

The structure of aluminium phosphate is crucial because it determines many of its properties and applications. AlPO4 has a three-dimensional network structure similar to silica (SiO2), which gives it stability and unique characteristics that make it useful in various industries.

22. How does the structure of aluminium phosphate compare to that of silica?

Aluminium phosphate has a structure analogous to silica (SiO2), where silicon atoms are replaced by alternating aluminium and phosphorus atoms. This structural similarity results in some shared properties between the two compounds, such as thermal stability and ability to form porous materials.

23. What are the main crystalline forms of aluminium phosphate?

The main crystalline forms of aluminium phosphate are berlinite (α-AlPO4), which is structurally similar to α-quartz, and tridymite-like AlPO4. These different forms have slightly different properties and can be used for various applications.

24. How does the structure of aluminium phosphate contribute to its use in chromatography?

The porous structure of aluminium phosphate, particularly in its molecular sieve form, makes it useful in chromatography. Its uniform pore size allows for the separation of molecules based on size and polarity, making it effective in both gas and liquid chromatography.

25. What is the significance of aluminium phosphate in the production of molecular sieves?

Aluminium phosphate is used to create molecular sieves known as AlPOs (aluminophosphates). These materials have uniform pore sizes and can selectively adsorb molecules based on their size, making them useful in gas separation and purification processes.

26. What role does aluminium phosphate play in the production of flame retardants?

Aluminium phosphate is used in some flame retardant formulations due to its ability to form a protective char layer when exposed to high temperatures. This char acts as an insulating barrier, slowing the spread of fire.

27. How does the crystal structure of aluminium phosphate change under high pressure?

Under high pressure, aluminium phosphate can undergo phase transitions, changing its crystal structure. These pressure-induced changes can alter its properties, potentially leading to new applications in high-pressure environments.

28. What is the significance of aluminium phosphate in the context of geochemistry?

In geochemistry, aluminium phosphate minerals like wavellite and variscite are important indicators of phosphorus cycling in the environment. Their formation and dissolution can influence phosphorus availability in soils and sediments.

29. How does aluminium phosphate compare to other metal phosphates in terms of thermal expansion?

Aluminium phosphate generally has a lower coefficient of thermal expansion compared to many other metal phosphates. This property makes it useful in applications where dimensional stability under temperature changes is important, such as in ceramics and refractory materials.

30. What is the role of aluminium phosphate in the production of specialty glasses?

Aluminium phosphate is used in some specialty glasses to improve their chemical durability and resistance to weathering. It can also modify the refractive index and other optical properties of the glass.

31. How does the presence of aluminium phosphate affect the setting time of cement?

When added to cement, aluminium phosphate can act as a setting retarder. It slows down the hydration reactions, extending the workability time of the cement mixture. This can be beneficial in applications requiring longer setting times.

32. What is the significance of aluminium phosphate's ability to form gels?

The ability of aluminium phosphate to form gels is important in various applications, including as a thickening agent in some industrial processes and in the preparation of certain catalysts. These gels can have high surface areas and unique pore structures.

33. How does aluminium phosphate contribute to the properties of dental composites?

In dental composites, aluminium phosphate can improve the material's strength and wear resistance. It can also enhance the bond between the composite and tooth structure, leading to more durable dental restorations.

34. What is the role of aluminium phosphate in the production of zeolite-like materials?

Aluminium phosphate is a key component in the synthesis of aluminophosphate (AlPO) molecular sieves, which are zeolite-like materials. These materials have well-defined pore structures and are used in various applications, including catalysis and gas separation.

35. How does the presence of aluminium phosphate affect the corrosion resistance of metals?

Aluminium phosphate can be used in corrosion-resistant coatings for metals. It forms a protective layer that can inhibit the corrosion process by creating a barrier between the metal surface and the corrosive environment.

36. What is the significance of aluminium phosphate's ion exchange properties?

The ion exchange properties of aluminium phosphate are important in various applications, including water treatment and catalysis. It can exchange ions with its surroundings, allowing for the removal of certain ions from solutions or the modification of catalyst properties.

37. How does aluminium phosphate contribute to the properties of paper coatings?

In paper coatings, aluminium phosphate can improve the paper's printability, smoothness, and gloss. It can also enhance the paper's resistance to water and grease, making it useful for specialty paper products.

38. What is the role of aluminium phosphate in the production of phosphate fertilizers?

While not as common as other phosphates in fertilizers, aluminium phosphate can be used as a slow-release source of phosphorus in some specialty fertilizers. Its low solubility allows for gradual release of phosphate ions over time.

39. How does the presence of aluminium phosphate affect the properties of polymer composites?

When incorporated into polymer composites, aluminium phosphate can improve the material's flame retardancy, thermal stability, and mechanical properties. It can also enhance the polymer's resistance to chemical degradation.

40. What is the significance of aluminium phosphate in the context of archaeological preservation?

In archaeological preservation, aluminium phosphate treatments can be used to stabilize and protect certain types of artifacts, particularly those containing iron. It can form a protective layer that helps prevent further corrosion or degradation.

41. How does aluminium phosphate contribute to the properties of anti-reflective coatings?

Aluminium phosphate can be used in anti-reflective coatings due to its ability to form thin, transparent films with a specific refractive index. These coatings can reduce glare and improve light transmission in optical applications.

42. What is the role of aluminium phosphate in the production of advanced ceramics?

In advanced ceramics, aluminium phosphate can be used as a sintering aid, improving the densification and mechanical properties of the ceramic. It can also contribute to the ceramic's thermal and chemical resistance.

43. How does the presence of aluminium phosphate affect the rheological properties of suspensions?

Aluminium phosphate can modify the rheological properties of suspensions by interacting with other particles and altering the suspension's viscosity and flow characteristics. This is important in applications such as paints, coatings, and ceramic slurries.

44. What is the significance of aluminium phosphate in the context of nuclear waste management?

Aluminium phosphate materials are being studied for potential use in nuclear waste management due to their ability to incorporate and immobilize certain radioactive elements. Their chemical and thermal stability make them promising candidates for long-term waste storage.

45. How does aluminium phosphate contribute to the properties of high-temperature lubricants?

In high-temperature lubricants, aluminium phosphate can act as a solid lubricant additive. Its thermal stability and ability to form protective films on metal surfaces can help reduce friction and wear under extreme conditions.

46. What is the role of aluminium phosphate in the production of specialty inks?

Aluminium phosphate can be used in specialty inks to improve their adhesion to certain surfaces, enhance their durability, and modify their rheological properties. It can also contribute to the ink's resistance to fading and chemical degradation.

47. How does the presence of aluminium phosphate affect the properties of battery separators?

In some battery separators, aluminium phosphate can be used to improve the separator's thermal stability and mechanical strength. It can also enhance the separator's wettability and ion conductivity, contributing to better battery performance.

48. What is the significance of aluminium phosphate in the context of environmental remediation?

Aluminium phosphate materials can be used in environmental remediation to remove certain contaminants from water or soil. Their ability to adsorb heavy metals and other pollutants makes them useful in cleaning up contaminated sites.

49. How does aluminium phosphate contribute to the properties of photocatalysts?

Aluminium phosphate can be used as a support or modifier for photocatalysts. It can enhance the catalyst's surface area, improve its stability, and modify its electronic properties, potentially leading to better photocatalytic performance.

50. What is the role of aluminium phosphate in the production of advanced sensor materials?

Aluminium phosphate-based materials are being explored for use in advanced sensors due to their unique properties. They can be used to detect various gases, ions, or biomolecules, with applications in environmental monitoring, medical diagnostics, and industrial process control.