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Phosphoric Acid

It finds extensive application in the fields of dentistry and orthodontics for tasks such as etching, crafting dental appliances, and forming fillings. Food-grade phosphoric acid is employed to acidify a variety of food and beverage products, including certain colas and jams. Given its non-toxic nature, phosphoric acid serves diverse industries in various capacities. It is also utilized as a sanitizing agent in the dairy, food, and brewing sectors. Additionally, it has a wide range of uses as a pH adjuster in cosmetics and skincare products.

Synonyms
Orthophosphoric acid, Phos acid
Chemical Formula
H3PO4
CAS Number
7664-38-2

Characteristics

Molar Weight
97.994g/mol
Melting Point
40–42.4 °C
Boiling Point
212 °C
Density
1.684 g/cc
Forms
Liquid, Viscous, White

Uses and Applications

Key applications

  • Food packaging
  • Food and Nutrition
  • Cleaning products
  • Pulp and paper
  • Solvents
  • Personal care
  • Cosmetic products
  • Agricultural (non-pesticide)
  • Bleaching agent
  • Electronics
  • Paint and Coatings

Phosphoric acid

Phosphoric acid (H3PO4) is the most important acid of the element phosphorus. It occupies a central position among the inorganic acids and is used in many different industries.
As phosphoric acid ester and in the form of polyphosphates, phosphoric acid also plays an elementary role in the human metabolism. Among other things, it is an important component of the energy transmitter adenosine triphosphate (ATP). Phosphoric acid is also a component of DNA, RNA and many coenzymes. Together with calcium, it forms hydroxyapatite in the body, which is what bones and teeth are made of.
Properties of phosphoric acid
In high concentrations, phosphoric acid is corrosive. It is a colourless and odourless solid. It is a weak to moderately strong, three-proton acid. The salts and esters of phosphoric acid are called phosphates, the latter are also known as organophosphates.
The chemical is strongly hygroscopic and can be mixed with water. It is usually distributed as an 83 to 90 percent aqueous solution. Phosphoric acid has good conductivity.
Phosphoric acid is produced from raw phosphate - usually the mineral apatite - and sulphuric acid, hydrochloric acid or nitric acid. Alternatively, so-called thermal phosphoric acid can be produced by burning phosphorus to form phosphorus pentoxide with subsequent hydrolysis.
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Phosphoric acid in agriculture

Industrial production of phosphoric acid focuses on the manufacture of phosphate-containing fertiliser. In addition, phosphoric acid is used as an additive and flavouring in animal feed.
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Phosphoric acid in the food industry

In the food industry, the additive phosphoric acid bears the name E338. Phosphoric acid is used in diluted form as a preservative and acidifier for beverages - for example cola - and foods such as jam, and as an acidity regulator. It also serves as an antioxidant, i.e. it prevents fats from becoming rancid or meat and sausage from discolouring.
Phosphoric acid is also used as a disinfectant in milk production, the food industry and in breweries.
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Phosphoric acid in the cosmetics industry

Phosphoric acid is used as a pH regulator in cosmetic and skin care products. It is also used in the production of shower gels and perfumes, hair care products and dyes, nail products and make-up.
Person cleaning bath

Phosphoric acid in the household

Phosphoric acid is an important ingredient in detergents and cleaning agents as well as liquid toilet cleaners. With such highly effective all-purpose cleaners, stubborn dirt, lime scale and deposits, urine scale or grease, such as soap scum, can be effectively removed from various surfaces.
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Phosphoric acid in medicine

Phosphoric acid functions as a pharmaceutical excipient, for example in the acidification or pH regulation of medicines.
Dentistry uses phosphoric acid to produce temporary dental cement as a filling for caries. In orthodontics, phosphoric acid acts as an etching solution that cleans and roughens the tooth surface before brackets, for example, are inserted. In tooth whitening solutions, phosphoric acid removes plaque.
Phosphoric acid also plays a role in anti-nausea medicines.
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Phosphoric acid in the construction industry

Phosphoric acid acts as a metal stain and corrosion inhibitor in the construction industry and is used to remove mineral deposits, concrete haze and lime stains.

Other uses of phosphoric acid

Phosphoric acid is used in the chemical industry to produce buffer solutions. It also acts as a rust remover or converter and is used to passivate iron and zinc to protect them from corrosion. In addition, phosphoric acid serves as an electrolyte in phosphoric acid fuel cells.
In microelectronics, heated phosphoric acid is used to etch silicon nitride. Mixtures of the acid are also suitable for etching aluminium. As a flux, it can simplify the soldering process. In hydroponics pH solutions, it lowers the pH value of nutrient solutions.
Another field of application for phosphoric acid is the processing of compound semiconductors, where it acts as a wet etchant. It is also used as an electrolyte in the electropolishing of copper for deburring.
Last but not least, phosphoric acid is used in the extraction of crude oil and in cases of water treatment.