There are more than a dozen different oxides of iron that occur naturally in various mineral deposits. Iron oxide has been used as a pigment by humans since prehistory, and was common ingredient used for cave painting. Nowadays, iron oxide can be naturally excavated or synthesised. Red iron oxide pigment is an inorganic synthetic component obtained from iron(II) sulfate using the Penniman–Zoph method, yellow and brown pigments are derived from limonite and magnetite produces a black pigment. Synthetic pigments are manufactured under previously studied conditions that improve the properties of the pigments, resulting in superior uniformity, color quality and chemical purity.
Iron oxide is a non-toxic compound that is safe to use in cosmetics, even on sensitive skin. It has been used in the cosmetic industry since the early 20th century as natural, inexpensive, and durable pigments. Modern cosmetics usually use synthetic oxides, giving the products an intense long lasting colour. Its natural resistance to moisture also prevents it from smearing easily. They can be found in a wide range of cosmetic products from eye shadow, eyeliner, and mascara; to blushes, face powder, hair dye, and lipstick.
In addition to reds, iron oxide can also be used to make green and brown glass. Its addition to glass is commonly used in beer bottles, and together with chromium, gives a richer green colour in wine bottles. The darker glass helps to reduce the transparency and therefore the degradation of the contents due to light exposure. In early glass making, a green colour was observed as the sand used often contained iron, giving it a natural green colour.
It is an abundant and undesired by-product of the steel making industry but the rust can be reused in applications that require iron oxides. Research into uniform α–Fe2O3 Nanospheres to form anodes for hybrid Ni-Fe cell devices, could prove to be a valuable and sustainable source of energy, and a possible alternative to Lithium-based batteries.
GO-Fe2O3, a graphene-oxide and iron oxide compound, has produced promising data which suggests that it may be an efficient heterogeneous catalyst of organic contaminants. In studies it has show to exhibit excellent catalytic properties for a wide pH range; the researchers hope that it can one day be used for water treatment.
Recent studies have shown promising results for the use of iron oxide nanoparticles in medical applications, including magnetic resonance imaging (MRI), magnetic hyperthermia, tissue repair, and drug delivery, namely for their superparamagnetism. Superparamagnetism is a behaviour exhibited by ferromagnetic nanoparticles; At these dimensions, the magnetisation of the particles can randomly flip direction when exposed to a change in temperature. As well as being used in MRI, iron oxides have the potential to be uses as nanoadjuvants in the manufacture of vaccines and antibodies.