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Zinc Oxide

Zinc oxide is an inorganic compound and white powder that is insoluble in water. Although it occurs naturally as the mineral zincite, most zinc oxide is produced synthetically.

Synonyms
Zinc white, oxozinc
Chemical Formula
ZnO
CAS Number
1314-13-2

Characteristics

Molar Weight
81.4 g/mol
Melting Point
1,975°C (decomposes)
Flash Point
1,436°C
Density
5.606 g/cm³
Forms
Powder, White

Uses and Applications

Key applications

  • Flux
  • Fungicide
  • Nutritional supplements
  • Antibacterial
  • UV protection
  • Animal feed
  • Binding agent

Zinc oxide

Zinc oxide is a chemical compound of zinc and oxygen. In nature, zinc oxide occurs in the form of the coarse-grained mineral zincite (red zinc ore).

Properties of zinc oxide

Zinc oxide has the chemical formula ZnO. It forms colourless, hexagonal crystals and - due to the refraction of light in very small crystals - a loose, white powder.

Zinc oxide can be obtained by burning zinc. In the laboratory, zinc oxide can be produced by precipitation from zinc salt solutions. The resulting zinc carbonate or zinc hydroxide can be converted into zinc oxide by annealing.
In the industrial extraction of zinc oxide using the so-called “American process”, the zinc ores are roasted, reduced to zinc with coal and then immediately oxidised again. In the "French process", pure zinc vapour is burnt with air; this produces the zinc white known as "painter's pigment". Depending on the area of application, zinc oxide can be produced in different qualities by varying the reaction conditions.

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Zinc oxide in the paint and varnish industry

Zinc oxide is used as a white colourant in paints, which is where the name "zinc white" comes from. In contrast to lead white paints, zinc oxide is resistant to hydrogen sulphide and light. In paints, it absorbs UV light and thus significantly reduces the ageing process in paint coatings.

Zinc oxide is also used in binders due to its antibacterial properties - it inhibits the growth of microorganisms on surfaces, which is particularly relevant for use in humid environments. Zinc white is used in anti-rust coatings to protect metallic surfaces from corrosion. In paints and varnishes, zinc oxide helps to improve texture.
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Zinc oxide in the construction industry

In the construction industry, zinc oxide is added as an additive to various building materials such as concrete, mortar, plaster and cement. It helps to improve strength, durability and corrosion resistance. Due to its flame-retardant properties, zinc oxide increases fire safety in building materials and coatings.
It is also used in building materials such as paints, coatings and sealants to inhibit the growth of mould and bacteria. Zinc oxide is also used in anti-corrosion coatings for steel structures. In thermally insulating building materials and insulation materials, zinc oxide improves the thermal insulation properties. Zinc oxide is also used in the electronics and welding industries.
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Zinc oxide in medicine

Zinc oxide is also important in the pharmaceutical industry. Zinc ointments, zinc pastes or zinc dressings for skin and wound treatment often contain zinc oxide due to its antiseptic effect. Zinc oxide is used in dentistry; in food supplements it serves as a source of zinc.
Plastics colored objects and small pieces colored in white

Zinc oxide in the polymer industry

Similar to paints and varnishes, zinc oxide is used in polymers as a UV stabiliser. It protects plastics from the harmful effects of ultraviolet radiation, which can lead to premature ageing, embrittlement and colour changes.
The antibacterial properties of zinc oxide are also utilised in polymers to inhibit the growth of microorganisms on the surface. This is particularly important in plastic applications for medical devices or food packaging.
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Zinc oxide in the cleaning industry

As zinc oxide absorbs and neutralises odours, it is used in the cleaning industry in air fresheners, for example. Thanks to its antibacterial and antimicrobial properties, zinc oxide inhibits the growth of bacteria and microorganisms on surfaces in bathroom and kitchen cleaners. Zinc oxide also acts as UV protection for textiles.
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Zinc oxide in agriculture

In the agricultural industry, zinc oxide is added to fertilisers and pesticides to promote plant growth and inhibit disease infestation. In animal nutrition, zinc oxide is often used as a source of zinc in feed for farm animals.