- Zinc oxide (ZnO) is an inorganic compound composed of zinc and oxygen, typically appearing as a fine, white powder that is insoluble in water but soluble in acids and bases. It naturally occurs as the mineral zincite but is more commonly produced synthetically for industrial and pharmaceutical applications. Zinc oxide possesses a unique combination of chemical, optical, and antimicrobial properties, making it a highly versatile material used across a broad range of industries, including cosmetics, medicine, electronics, and rubber manufacturing.
- One of the most familiar uses of zinc oxide is in skin care and personal care products, particularly in sunscreens, diaper rash creams, calamine lotions, and anti-dandruff shampoos. As a physical (mineral) UV filter, ZnO provides broad-spectrum protection against both UVA and UVB rays by reflecting and scattering ultraviolet light. It is considered safe and non-irritating, even for sensitive skin, which is why it is widely used in formulations for infants and people with skin disorders. Its soothing and mildly antiseptic properties also make it effective in treating minor skin irritations, burns, and wounds.
- Zinc oxide is also a crucial component in rubber and tire manufacturing, where it functions as an activator in the vulcanization process. It helps improve the durability, elasticity, and resistance of rubber products. In the ceramics industry, ZnO is used in glazes and frits to enhance brightness and hardness. In paints and coatings, it acts as a pigment and mildew-resistant agent.
- In electronics and materials science, ZnO exhibits semiconducting, piezoelectric, and photocatalytic properties, which make it useful in the fabrication of sensors, varistors, transistors, LEDs, and solar cells. Its wide band gap and high exciton binding energy make it suitable for optoelectronic applications, especially in the development of transparent thin films and nanomaterials.
- Zinc oxide also has notable antibacterial and antifungal properties, which contribute to its use in medical applications such as wound dressings and dental materials. It helps create a hostile environment for microbial growth, which can prevent infection and promote healing.
- Although zinc oxide is generally regarded as safe when used externally, inhalation of ZnO fumes, such as those generated during welding or industrial processes, can lead to a condition known as metal fume fever, a temporary illness characterized by flu-like symptoms. In nanoparticle form, zinc oxide has raised concerns about toxicity and environmental impact, particularly in aquatic ecosystems, prompting ongoing research and regulatory scrutiny.
