Iron oxide

Iron oxide

  • CAS: 1332-37-2
  • FOB Price:1 USD/Kilogram Get Latest Price
  • Port:Shanghai
  • Minimum Order Quantity:1/Kilogram
  • Supply Ability:20 Metric Ton/Year
  • Payment Terms:T/T, L/C
  • Updatetime:Jun 26 2017
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  • Cas NO.:1332-37-2
  • EINECS:215-570-8
  • IUPAC Name: oxoiron
  • Molecular Weight:71.8444
  • H bond acceptors: 1
  • Purity:95%, 99%
  • Appearance:powder
  • Polar Surface Area: 17.07A2
  • InChI: 1S/2Fe.3O/q2*+3;3*-2

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Detailed Description

Iron oxide are a group of compounds made up of iron and oxygen linked together by chemical bonds. The rust you see on metal is an example of natural iron oxide formation. Rust forms when iron is exposed to oxygen and water, and a chemical reaction called oxidations occurs. During the rusting process, iron atoms bond with oxygen atoms to create Iron oxide that are typically red, brown or orange in color. Water is necessary for Iron oxide to form, either in the form of water or moisture from the air. Most Iron oxide are now produced synthetically under more controlled circumstances since naturally oxidized iron can contain impurities like heavy metals that aren't desirable and may be harmful.
Iron oxide abound in nature where they serve a variety of biological functions. In addition, they're used as an ingredient in household and personal care products. One way they're commonly used is to make paint pigments used by artists. They're also used to dye concrete, tiles, rubber and leather. Iron oxide form deep yellow or orange shades and various shades of red and brown, so they're ideal for creating earth-tone paints and pigments. There are also black oxides that are deep black in color. Iron oxide have been used as paint pigments since very early times to create earthy colors like umber and sienna that artistic people can use to paint realistic landscape paintings.
Iron oxide is also used in the manufacture of electronic parts and magnets and to create the magnetic strip on the back of credit cards and ATM cards. In addition, they're used in the pharmaceutical industry to add color to tablets and capsules. More recently, iron oxide nanoparticles have been used to deliver drugs and medications to specific areas of the body.
Another area were Iron oxide are useful is in the cosmetic and personal care industry, Because Iron oxide come in shades or red, orange, brown and black, cosmetic manufacturers use them to add color to cosmetic products like eye shadow, blush, face powders, lipstick and mineral makeup. Using Iron oxide as coloring agents in cosmetics has some advantages. They're resistant to moisture, don't easily bleed or smear and have "staying power" so you don't have to keep reapplying your eye shadow or blush. They also create intense pigments that have a rich color.
Iron oxide pigments work well in makeup products that remain on the surface of the skin, but they aren't ideal for permanent makeup placed beneath the skin. When they're placed into the dermis of the skin during the application of permanent makeup, the iron is gradually absorbed by blood vessels in the dermis, and the color can change or fade. Therefore, iron oxide pigments aren't truly permanent when injected subcutaneously.
Iron oxide are found in a wide array of cosmetic products from eye shadow to talcum powder - even products that are marketed as natural or organic. That's because they're safe, although the iron oxide in cosmetics is made synthetically. Iron oxide are made in a lab for safety reasons since naturally produced varieties often contain impurities. These impurities aren't an issue when Iron oxide are made under carefully controlled conditions. Cosmetic-grade Iron oxide are made from mined iron salts that are then oxidized in a laboratory and purified. Oxides formed in a natural, uncontrolled setting are often contaminated with heavy metals like arsenic, mercury and cadmium. This is an example of natural not always being safer.
Iron oxide are gentle and non-toxic in cosmetic products placed on the surface of the skin, although they aren't suitable for permanent cosmetics placed into the dermal layer of the skin since they can be absorbed by blood vessels and lead to color changes. They're usually not irritating to the skin and aren't known to allergenic. The few reports of allergic reactions to Iron oxide have turned out to be an allergy to nickel instead. Iron oxide typically don't cause problems even for people with sensitive skin. All in all, they're safe and non-irritating in the amounts found in cosmetic products.

Iron oxide Uses

Iron oxide, spent (CAS NO.1332-37-2) is used in ceramic applications, particularly in glazing. It is also widely used in the cosmetic field. It can also be used in electrochromic paints. Combined with aluminium powder, iron oxide forms thermite, which is used in demolition and bomb building.

Iron oxide Consensus Reports

Reported in EPA TSCA Inventory.

Standards and Recommendations

DOT Classification: 4.2; Label: Spontaneously Combustible

Iron oxide Specification

The Iron oxide, spent (Fe3O4/FeO) is a two-step thermochemical process used for hydrogen production. It is a flammable solid, should be kept away from sparks and flames.

Iron oxide surfaces

The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1?xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1?xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces.
The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed.
The best understood iron oxide surface at present is probably Fe3O4(100); the structure is known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Feoct–O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10?7?10?5 mbar O2 in the final stage of preparation. Such straightforward preparation of a monophase termination is generally not the case for iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch–Cohen defects in Fe1?xO. The cation deficiency results in Fe11O16 stoichiometry, which is in line with the chemical potential in ultra-high vacuum (UHV), which is close to the border between the Fe3O4 and Fe2O3 phases. The Fe3O4(111) surface is also much studied, but two different surface terminations exist close in energy and can coexist, which makes sample preparation and data interpretation somewhat tricky. Both the Fe3O4(100) and Fe3O4(111) surfaces exhibit Fe-rich terminations as the sample selvedge becomes reduced. The Fe3O4(110) surface forms a one-dimensional (1×3) reconstruction linked to nanofaceting, which exposes the more stable Fe3O4(111) surface. α-Fe2O3(0001) is the most studied haematite surface, but difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called “bi-phase” structure is formed, which eventually transforms to a Fe3O4(111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe1?xO and α-Fe2O3(0001) islands was recently challenged and a new structure based on a thin film of Fe3O4(111) on α-Fe2O3(0001) was proposed. The merits of the competing models are discussed. The α-Fe2O3(11ˉ02) “R-cut” surface is recommended as an excellent prospect for future study given its apparent ease of preparation and its prevalence in nanomaterial.
In the latter sections the literature regarding adsorption on iron oxides is reviewed. First, the adsorption of molecules (H2, H2O, CO, CO2, O2, HCOOH, CH3OH, CCl4, CH3I, C6H6, SO2, H2S, ethylbenzene, styrene, and Alq3) is discussed, and an attempt is made to relate this information to the reactions in which iron oxides are utilized as a catalyst (water–gas shift, Fischer–Tropsch, dehydrogenation of ethylbenzene to styrene) or catalyst supports (CO oxidation). The known interactions of iron oxide surfaces with metals are described, and it is shown that the behaviour is determined by whether the metal forms a stable ternary phase with the iron oxide. Those that do not, (e.g. Au, Pt, Ag, Pd) prefer to form three-dimensional particles, while the remainder (Ni, Co, Mn, Cr, V, Cu, Ti, Zr, Sn, Li, K, Na, Ca, Rb, Cs, Mg, Ca) incorporate within the oxide lattice. The incorporation temperature scales with the heat of formation of the most stable metal oxide. A particular effort is made to underline the mechanisms responsible for the extraordinary thermal stability of isolated metal adatoms on Fe3O4 surfaces, and the potential application of this model system to understand single atom catalysis and sub-nano cluster catalysis is discussed. The review ends with a brief summary, and a perspective is offered including exciting lines of future research.

Where Iron oxide Comes From

Iron is a metallic element with the chemical symbol Fe, and is one of the most prolific and commonly occurring mineral substances on Earth. Scientists estimate that is found in approximately 5% of the planet's crust, and exists in its core, too. Iron turns to iron oxide when it comes into contact with oxygen, either on its own or in combination with other elements like water. When the mineral is exposed to water and air for extended periods of time it will usually produce rust, which is a reddish-brown oxide.
Deposits of iron oxide occur in the soil, too. Experts usually believe that these were created by the precipitation of iron from seawater during the Proterozoic Eon some 1.6 billion years ago. These deposits are found in locations around the world, though the greatest concentrations tend to be in what is now the United States, India, Australia, China, Brazil, and Russia.

Iron oxide Different Types

Iron oxidizes a couple of different ways, and the results fall across a spectrum with some being mostly iron and others mostly oxygen. The ending color and technical specifications vary accordingly. There are two primary forms, known as (II) and (III), of the oxide in nature, though different elements and compounds sometimes draw from both sources. Rust, for example, is known as iron (II, III) oxide and has the chemical structure Fe2O3, though the (II, III) designation is also given to magnetite, a compound with the structure Fe3O4; a number of other compounds can also be included in this grouping. In most cases numerical designations say more about how the elemental iron and oxygen bind together than what the substance looks like.

Iron oxide Use in Electronics

Among stable, room temperature elements, there are usually only three that are naturally magnetic, namely cobalt, nickel, and iron; among these, iron is usually the most magnetic, which manufacturers often capitalize on in the production of magnets, electronic parts, audio and video cassette tapes, and bank and magnetized credit cards. In these cases a bit of powdered oxide is combined with other elements and sealants to create magnetic tapes or bands that can be used to help keep working parts charged and in place. That the oxide occurs naturally in nature helps keep costs down, too.

Iron oxide Cosmetic Applications

The cosmetics industry uses the compound to create various pigments in make-up as well. Most oxide forms are non-toxic, water repellent, and do not run or bleed, making them an ideal additive to products like mascara, liquid and powder foundation, and eye shadow. Oxides can also be found in certain types of health products such as talcum powder, facial cream, and body cream. Some sunblock products contain it as well. Its structure is often thought to help block the sun's harmful ultraviolet rays from damaging human skin.

Iron oxide Importance in Art

In the art world, iron oxide is used to create pigments such as burnt sienna and burnt umber. Colors and paints made this way tend to be permanent and long lasting. Though the precise method of coloring paints has changed somewhat over time, the basic concept has been at play since the prehistoric age; the cave paintings at Lascaux, France, are just one example of how long this compound has been used and how well paints made with iron last. Modern manufacturers rarely rely on it alone to form base colors and pigment foundations, though it is often still an important ingredient.

Iron oxide In Industry

The compound in its various types and combinations has a range of different uses in industry. Pigments are frequently used to dye such things as commercial-grade paint, concrete, leather, and shoe polish, for example; products like tiles and rubber sometimes also contain it for color and stability. Iron oxide is also added to different nutrients, feeds, and medications in trace amounts, usually as a way of maintaining chemical balance between different active ingredients.

iron oxide Making Red Mud

Recovery and Recycling, and post-doctoral fellow Hyunju Lee use a magnetic separator to remove iron oxide. "We're trying to help the environment by getting rid of these ponds, which can leak and destroy surrounding ecosystems," said team leader Brajendra Mishra, director of WPI's Center for Resource Recovery and Recycling (CR3). "If our process is successful, we can produce a valuable product while also reclaiming that land." The process the WPI team has developed and extensively tested in the lab can extract a magnetic reduced iron oxide from red mud. The material can then be sold to companies that use it to make pigments for construction materials and produce a variety of agricultural applications for soil and crop growth. Depending upon its purity, the iron oxide can sell for up to several thousand dollars per ton. Since iron oxides can make up as much as 60 percent of red mud, a viable recovery method could be lucrative, Mishra says. After WPI receives the red mud, a two-step recovery process then takes place at WPI's Washburn laboratories. The mud, which looks like clay, first undergoes a gas-based carbothermic reduction process before being placed on an apparatus for separation. The team then uses a magnetic separator to remove the iron oxide from non-magnetic materials such as alumina, calcium silicate, and other elements. A valuable magnetic reduced iron oxide is extracted from red mud "We're the only ones with a process for producing the reduced iron oxide and converting it to a saleable product," said Mishra, adding that he expects patents to be placed on the process. Mishra, who joined WPI in 2015, began his red mud recovery research at the Colorado School of Mines in 1995, where he served as a professor of Corrosion and Physico-chemical Processing in Metallurgical & Materials Engineering. Mishra predicts that a commercial process to recover products from red mud will be developed within the next five years in the United States. "We can't afford to keep collecting red mud in ponds," he said. "The value in recovering materials from red mud would have a tremendous impact for the aluminum industry and for the economy."

using iron oxide pigments in paints

Iron oxide is an oxide of iron, which contains a variety of different colors, such as iron oxide blue, iron oxide brown, iron oxide red, etc., depending on the content of crystal water. Iron oxide is an important paint, so that the main method to make paint into colorful is to add different colors of iron oxide pigments. Let's take a look at how iron oxide can be used in paints:
First, the iron oxide paint for a variety of paint coloring and protective substances. Such as alkyd resins, amino alkyds, perchlorethylene resin, polyurethane, nitro, polyester paint and so on. In addition, it is also suitable for electrophoretic paint. Primer, enamel, pencil paint, blending paint, baking paint, anti-rust paint, floor paint, water paint and so on. Can also be used for water-based paints, powder coatings and plastic coatings. As well as for toy paint, decorative paint, furniture paint, house paint, garage paint, parking paint, automotive paint and so on.
Second, the use of methods: generally divided into three steps: wetting, grinding and dispersion (paint tone). Iron oxide pigments and paints, fillers in the mixing tank mix, dubbed thick paste, according to the amount of solvent added by the different viscosity and the use of different grinding equipment, such as thick paste can be three-roll thin, thin slurry can be milled using an efficient sand mill (vertical or horizontal) or a ball mill. Primer is generally about 50 microns, topcoat requirements in about 40 microns, and then in the tone paint tank, adding trees on purpose, dry materials, solvents, paint dispersion, color, adjust the viscosity, etc. Finally, Finished product packaging.
Third, the application: iron oxide pigments have good weather resistance, high purity, good thermal stability, and other components of the application system compatibility is good, can absorb ultraviolet light to prevent the degradation of base materials, coupled with low cost, can be widely used in paint. Because of strong hiding power, UV has a strong impermeability and a very small water absorption in the paint film can enhance the mechanical strength of the film, especially in the adhesion of the fine features of the other anti-rust paint such as red, zinc and other mixed use, can enhance the film stability and mechanical strength, is now widely used in a variety of outdoor paint, traffic paint, metal rust primer and topcoat. Iron oxide, iron green, mica iron oxide, transparent iron oxide products, of which a large amount of iron-red wide range of products is the product of iron oxide red, iron oxide yellow, iron oxide brown, iron oxide black, iron oxide green, iron oxide mica, transparent iron oxide products used in paint. Transparent iron is most suitable for automotive topcoat, wood coloring, can coating, medical packaging coloring and so on.

the Structure of 4D Iron Oxide

An international study group, including the Moscow State University of Russia, recently found the behavior of iron oxide Fe4O5. The organization has succeeded in describing its complex structure and providing an explanation of its unusual characteristics. This article was published in the latest issue of the journal Nature Chemistry. Scientists have found that when iron oxides of Fe4O5 are cooled to temperatures below 150 K, they undergo a "four-dimensional" crystal structure through the transformation of a specific phase transition associated with charge density waves. Artem Abakumov, one of the authors of the paper, says that the study of this material will help to understand the interconnections between magnetic and crystal structures.
The origins of this study can be traced back to 1939 when the German physicist E. J. W. Verwey first discovered the familiar magnetic iron ore (Fe3O4) strange phase transition. Normally, magnetite is a relatively good electrical conductor, but when the cooling below 120K, its conductivity decreased significantly, almost become an insulator. Scientists have found that below 120K, the iron atoms are arranged in an ordered structure. In this structure, electrons are not free to move, nor can they act as carriers, and even this oxide becomes a ferroelectric. But scientists can not explain what changed in the structure, physicists spend a lot of time to study. The researchers speculate that this phenomenon is related to the existence of iron atoms in two different oxidation states (divalent, trivalent), they can form an ordered structure.
The answer to this question was not discovered until 2012, and a team led by Professor Paul Attfield of Cambridge University synthesized high-quality magnetite crystals and explained their structure. The researchers say, as has already been suggested earlier, the so-called structural order occurs with trivalent and trivalent iron atoms arranged in three clusters of changes, which are called trimers. The authors of this paper decided to look at the different iron oxides - Fe4O5 (which was only recently discovered by an American research team). This is an unusual oxide that can only form at very high temperatures and pressures, which means that it can not be found on the surface of the earth, even in other oxides containing higher oxygen, now that it exists in the depth of several hundred kilometers below the Earth's surface.

Where do you live with traces iron oxide?

It is available in iron oxide pigments. It uses beyond count, can relate to every aspect of our lives, from the building to the basic necessities of life are iron oxide pigment useless, you can say it is a show of pigment in our life.
1. Iron oxide pigment is suitable for the coloring of plastic products, such as thermosetting plastics and thermoplastics, and rubber products, such as the inner tube of cars, the inner tube of a plane, the inner tube of a bicycle, etc..
2, iron oxide red is widely used in construction, rubber, plastic, paint and other industries, especially iron red primer with antirust function, can replace the expensive red lead paint, saving non-ferrous metals. High precision grinding materials, used in sophisticated hardware instruments, optical glass polishing. High purity is the main base of powder metallurgy, used for smelting various magnetic alloys and other advanced alloy steel. Made from ferrous sulfate or iron oxide yellow or inferior iron mixed by high temperature calcination or directly from liquid medium.
3, iron oxide red pigment in all kinds of concrete prefabricated parts and building materials as pigments or colorants, directly transferred to cement applications. Color concrete surface inside and outside, such as walls, floors, ceilings, pillars, porch, road, parking lot, ladder and station; a variety of architectural ceramics and glass ceramics, such as tiles, floor tiles, tiles, panels, terrazzo, mosaic tiles, artificial marble.
4, the red color in the building materials industry is mainly used for cement, cement color tile, color cement tile, imitation glazed tile, concrete brick, mortar, terrazzo, color color asphalt, mosaic tiles, artificial marble and stucco walls; in the industry is mainly used to produce all kinds of paint, paint, ink, paint. In other industries, such as ceramics, rubber, plastics, leather, wipes, etc., used as colorants and fillers.
5. Used in paint, rubber, plastics, building, etc., in addition, iron oxide pigment can also be used for various cosmetics, paper, leather coloring.
6, applicable to all kinds of iron oxide pigment coloring and coating protection material, including water and wall paint, such as powder coatings; can also be used in paint, alkyd, including epoxy primer and finish all kinds of amino; can also be used in toy paint, decoration paint, furniture paint, paint and enamel.

The market trend of iron oxide pigment is obvious

According to market research institutions latest analysis report shows that in 2017 the global iron oxide pigment market size of about 1 billion 830 million U. S. dollars. The growing demand for construction, coatings and plastics is driving the growth of iron oxide pigment manufacturers in this area.
Growth in the Asia Pacific and Middle East construction industry is expected to continue to drive the growth of the iron oxide pigment industry over the next 8 years. Favorable government regulations will further promote environmentally friendly products and technological advances, and will have a positive impact on the growth of iron oxide pigment market. LANXESS, BASF and other major global chemicals producer is through pigment products continue to improve technology and manufacturing of high quality, in order to meet regulatory standards, will also be on the R & D of different colors of synthetic and natural products have a positive impact.
Raw materials used in the production of synthetic iron oxide pigments include nitrobenzene and cast iron. Among them, increasing the scope of application of nitrobenzene in other industries is expected to raise its price, such as an intermediate product in the polishing agent, solvents, pesticides, dyes, deodorant, lubricant, synthetic rubber and other products have been used, so the expected factors will enhance the production cost of iron oxide pigment.
Synthetic iron oxide pigment is the most important species The iron oxide pigment industry includes natural products and synthetic products, and has a wide range of applications, such as construction, plastics, coatings, ceramics, inks, rubber, cosmetics and so on.
The synthetic iron oxide pigment is the most important market in 2017 due to its excellent purity and quality. Natural products are expected to grow more rapidly over the next 8 years because of their low price and ample availability.
There are a variety of synthetic iron oxide pigment production process, such as precipitation, calcination, Loucks (Laux) and Penniman (Penniman), the progress of technology and the increase of demand for environmentally friendly products, is expected to continue to drive the continuous improvement of production process.
Pigment is the focus of development
Iron oxide pigment has a variety of colors, such as red, yellow, black, orange, brown, etc.. Red iron oxide pigment is the most widely used and has the greatest demand compared with other color varieties.
Loucks process is technical path of producing iron Confidante material is the most important, but the technology also need to continuously improve, so enterprises can rely on the production of some well-known leading technology market.
Applications in the coatings industry will grow fastest Iron oxide pigments are used in many industrial products, including construction, plastics, coatings, paints, paper and so on.
In the plastics industry, iron oxide pigments give colour to products, including food packaging, vinyl plates, home computers, automotive components, fenders, soda bottles, and toys. Building materials are the largest market for iron oxide pigments in 2017, and their products are of high demand, especially in the field of concrete.
In addition, iron oxide pigment used in paints and coatings market is expected to be the fastest growth rate, in the field of paint application, also need to keep the paint film of iron oxide pigment strength and optimize coloring effect.
The Asia Pacific region maintains a leading position in the global market
The Asia Pacific region is leading the global market for iron oxide pigments, accounting for 41.7% of global consumption in 2017, due to growing infrastructure and rapid industrialization, especially in China and India.
Due to the reduction of infrastructure construction activities, the growth rate of iron oxide pigments in Europe is expected to be relatively stable over the next 8 years. The iron oxide pigment industry in the Middle East and Africa is expected to grow at a remarkable rate, especially in Nigeria, Saudi Arabia and qatar.

How to deal with the waste residue of iron oxide red production?

At present there are many methods to produce iron oxide red, but many methods in use, there will be some impurity processing deal, but these so-called waste can be used in different ways such as the production of iron oxide red waste sulfuric acid slag, slag composition produced after production in containing many insoluble in acid substances not with acid hydrolysis, mainly iron ore, which is basically the same to write impurities at home and abroad, is used in the filter processing, can only reach 98% of titanium liquid recovery. Here's a brief introduction to the process

The acid sludge into the storage tank in dedicated, diluted after delivery pump into the filter, and then through the settlement process, the last remaining impurities is not available, then the artificial will be transported to the reasonable place for deep buried or unified stacking.

The impurity treatment production has been reasonable in all the concerns of the enterprise, and it is our positive research into the direction, believe that through the efforts of researchers, factory waste will be less and less.

The application and characteristics of iron oxide red

The chemical substances in black iron oxide is a relatively common, at present, the domestic sales of red iron oxide is mainly used in some coloring process, other applications are more, because iron oxide red possesses good tinting strength, in addition to the red iron oxide in lower prices, is a kind of high quality and inexpensive products, so by the vast number of consumers, in the end it's application in how to reflect the performance?

In general use as a colorant, can be directly mixed with various concrete, depending on the product has good compatibility, can also be used in some water paint field or paint, can be used in various indoor and outdoor concrete or water mud material colorant. In glass ceramics will often use iron oxide red, mainly painted on the wall surface, all kinds of brick surface, floor tiles, pavement and other fields.

The reason why there are so many applications, because it has good chemical resistance, can be resistant to high alkali environment; secondly can withstand different temperature change, not with the temperature change on the performance change; heat resistance of final products can be used in high temperature environment.

Environmental protection prospect of iron oxide coatings

Inorganic paint is a very environmentally friendly dyes, in general, his basic materials are taken from nature, not only rich in resources, but also green dye, loved by people. Iron oxide paint has entered the construction, painting and other industries in an inorganic coating way, and has won the unanimous praise of the masses. Green is the biggest advantage of iron oxide, creating opportunities for his bright future.

According to a survey in recent years, China's ecological environment has been seriously damaged, green environmental protection has become the country attaches great importance to the issue, at the same time on all walks of life also put forward the requirements of environmental protection, but also the direction of development of the paint industry, iron oxide coatings as the inorganic coating, a bright future development. Organic coatings have good decorative and diverse characteristics, and the characteristics of iron oxide coatings have become an important factor for their extensive use. Developed countries in all aspects of the building coating requirements are very high, attaches great importance to research and application properties of inorganic coatings, although our country in this field started relatively late, but with the development of science and technology, I believe that in the near future will be very high achievement.

Iron oxide coating has good anti pollution performance and excellent environmental performance, with these two points on environmental issues, he established a variety of advantages, but also has the basic properties of the coating, which makes him have a stable position in the paint industry. At the same time, many kinds of iron oxide paint, such as iron oxide red, iron oxide blue, iron oxide red paint, iron oxide red function is complete, in the market has become the highest demand paint. On environmental protection, iron oxide paint has a very good prospect, it can be an example of other coatings, with the development of science and technology, iron oxide paint will lead the new trend of environmental protection in the future.

Action and field of iron oxide red

As we all know, iron oxide pigment has a wide range of applications, and the role is very large, and the best selling in the paint market is iron oxide pigment. Among them, the role of iron oxide red is also very large, and its application areas include many aspects, the following by small make up for everyone to explain.

With the development of the construction industry, the construction industry has a relationship with the gradually integrated into the development direction, the iron oxide Confidante material is one of them, we all know that Confidante material is iron oxide as a pigment or colorant into cement, cement into the application of iron oxide red in various fields, many color mud concrete is added to the cement to form bright colors, like the ceiling, pillar, porch, road, parking lot, ladder has disappeared. With the development of coating industry, all kinds of pigments, the demand is very big, very suitable for various kinds of paint coloring, such as powder coating, in addition, by virtue of its pigment coloring is very good, has been well received in the paint industry, whether it is or is a primer coat as iron oxide red pigment. The wide range of applications. In our society there is a material food color, it is very hot plastic, along with the development of society and scrap industry, its application scope and recyclable products, so favored by the vast number of consumers, so that in the plastics industry is also very popular, iron oxide red is harmless, no any damage to the human body, so can be used in all walks of life. With the advantage of harmless to the human body, iron oxide red in cosmetics industry also has a certain position, I believe that with the development of science and technology, iron oxide red will be applied in all walks of life.

Iron Oxide and Iron

Iron Oxide is a chemical element with symbol Fe (from Latin: ferrum) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars, where it is the last element to be produced with release of energy before the violent collapse of a supernova, which scatters the Iron Oxide into space.

Like the other group 8 elements, ruthenium and osmium, Iron Oxide exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental Iron Oxide occurs in meteoroids and other low oxygen envIron Oxidements, but is reactive to oxygen and water. Fresh Iron Oxide surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated Iron Oxide oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, Iron Oxide oxides occupy more volume than the metal and thus flake off, exposing fresh surfaces for corrosion.

Iron Oxide metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure Iron Oxide is relatively soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon, from the smelting process. A certain proportion of carbon (between 0.002% and 2.1%) produces steel, which may be up to 1000 times harder than pure Iron Oxide. Crude Iron Oxide metal is produced in blast furnaces, where ore is reduced by coke to pig Iron Oxide, which has a high carbon content. Further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and Iron Oxide alloys formed with other metals (alloy steels) are by far the most common industrial metals because they have a great range of desirable properties and Iron Oxide-bearing rock is abundant.

Iron Oxide chemical compounds have many uses. Iron Oxide oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron Oxide forms binary compounds with the halogens and the chalcogens. Among its organometallic compounds is ferrocene, the first sandwich compound discovered.

Iron Oxide plays an important role in biology, forming complexes with molecular oxygen in hemoglobin and myoglobin; these two compounds are common oxygen transport proteins in vertebrates. Iron Oxide is also the metal at the active site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants and animals. A human male of average height has about 4 grams of Iron Oxide in his body, a female about 3.5 grams. This Iron Oxide is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma.


Mechanical properties

The mechanical properties of Iron Oxide and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test and the Vickers hardness test. The data on Iron Oxide is so consistent that it is often used to calibrate measurements or to compare tests. However, the mechanical properties of Iron Oxide are significantly affected by the sample's purity: pure, single crystals of Iron Oxide are actually softer than aluminium, and the purest industrially produced Iron Oxide (99.99%) has a hardness of 20–30 Brinell.An increase in the carbon content will cause a significant increase in the hardness and tensile strength of Iron Oxide. Maximum hardness of 65 Rc is achieved with a 0.6% carbon content, although the alloy has low tensile strength. Because of the softness of Iron Oxide, it is much easier to work with than its heavier congeners ruthenium and osmium.

Molar volume vs. pressure for α Iron Oxide at room temperature

Because of its significance for planetary cores, the physical properties of Iron Oxide at high pressures and temperatures have also been studied extensively. The form of Iron Oxide that is stable under standard conditions can be subjected to pressures up to ca. 15 GPa before transforming into a high-pressure form, as described in the next section.

Phase diagram and allotropes

Iron Oxide represents an example of allotropy in a metal. There are at least four allotropic forms of Iron Oxide, known as α, γ, δ, and ε; at very high pressures and temperatures, some controversial experimental evidence exists for a stable β phase.

As molten Iron Oxide cools past its freezing point of 1538 °C, it crystallizes into its δ allotrope, which has a body-centered cubic (bcc) crystal structure. As it cools further to 1394 °C, it changes to its γ-Iron Oxide allotrope, a face-centered cubic (fcc) crystal structure, or austenite. At 912 °C and below, the crystal structure again becomes the bcc α-Iron Oxide allotrope, or ferrite. Finally, at 770 °C (the Curie point, Tc) Iron Oxide's magnetic ordering changes from paramagnetic to ferromagnetic. As the Iron Oxide passes through the Curie temperature there is no change in crystalline structure, but there is a change in "domain structure", where each domain contains Iron Oxide atoms with a particular electronic spin. In unmagnetized Iron Oxide, all the electronic spins of the atoms within one domain have the same axis orientation; however, the electrons of neighboring domains have other orientations with the result of mutual cancellation and no magnetic field. In magnetized Iron Oxide, the electronic spins of the domains are aligned and the magnetic effects are reinforced. Although each domain contains billions of atoms, they are very small, about 10 micrometres across. This happens because the two unpaired electrons on each Iron Oxide atom are in the dz2 and dx2 − y2 orbitals, which do not point directly at the nearest neighbors in the body-centered cubic lattice and therefore do not participate in metallic bonding; thus, they can interact magnetically with each other so that their spins align.

At pressures above approximately 10 GPa and temperatures of a few hundred kelvin or less, α-Iron Oxide changes into a hexagonal close-packed (hcp) structure, which is also known as ε-Iron Oxide; the higher-temperature γ-phase also changes into ε-Iron Oxide, but does so at higher pressure. The β-phase, if it exists, would appear at pressures of at least 50 GPa and temperatures of at least 1500 K and have an orthorhombic or a double hcp structure.[11] These high-pressure phases of Iron Oxide are important as endmember models for the solid parts of planetary cores. The inner core of the Earth is generally presumed to be an Iron Oxide-nickel alloy with ε (or β) structure.[14] Somewhat confusingly, the term "β-Iron Oxide" is sometimes also used to refer to α-Iron Oxide above its Curie point, when it changes from being ferromagnetic to paramagnetic, even though its crystal structure has not changed.

The melting point of Iron Oxide is experimentally well defined for pressures less than 50 GPa. For greater pressures, studies put the γ-ε-liquid triple point at pressures that differ by tens of gigapascals and 1000 K in the melting point. Generally speaking, molecular dynamics computer simulations of Iron Oxide melting and shock wave experiments suggest higher melting points and a much steeper slope of the melting curve than static experiments carried out in diamond anvil cells.[15] The melting and boiling points of Iron Oxide, along with its enthalpy of atomization, are lower than those of the earlier 3d elements from scandium to chromium, showing the lessened contribution of the 3d electrons to metallic bonding as they are attracted more and more into the inert core by the nucleus;[16] however, they are higher than the values for the previous element manganese because that element has a half-filled 3d subshell and consequently its d-electrons are not easily delocalized. This same trend appears for ruthenium but not osmium.


Naturally occurring Iron Oxide consists of four stable isotopes: 5.845% of 54Fe, 91.754% of 56Fe, 2.119% of 57Fe and 0.282% of 58Fe. Of these stable isotopes, only 57Fe has a nuclear spin (− 1⁄2). The nuclide 54Fe theoretically can undergo double electron capture to 54Cr, but the process has never been observed and only a lower limit on the half-life of 3.1×1022 years has been established.

60Fe is an extinct radionuclide of long half-life (2.6 million years). It is not found on Earth, but its ultimate decay product is its granddaughter, the stable nuclide 60Ni.[17] Much of the past work on isotopic composition of Iron Oxide has focused on the nucleosynthesis of 60Fe through studies of meteorites and ore formation. In the last decade, advances in mass spectrometry have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of Iron Oxide. Much of this work is driven by the Earth and planetary science communities, although applications to biological and industrial systems are emerging.

In phases of the meteorites Semarkona and Chervony Kut, a correlation between the concentration of 60Ni, the granddaughter of 60Fe, and the abundance of the stable Iron Oxide isotopes provided evidence for the existence of 60Fe at the time of formation of the Solar System. Possibly the energy released by the decay of 60Fe, along with that released by 26Al, contributed to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of 60Ni present in extraterrestrial material may bring further insight into the origin and early history of the Solar System.

The most abundant Iron Oxide isotope 56Fe is of particular interest to nuclear scientists because it represents the most common endpoint of nucleosynthesis. Since 56Ni (14 alpha particles) is easily produced from lighter nuclei in the alpha process in nuclear reactions in supernovae (see silicon burning process), it is the endpoint of fusion chains inside extremely massive stars, since addition of another alpha particle, resulting in 60Zn, requires a great deal more energy. This 56Ni, which has a half-life of about 6 days, is created in quantity in these stars, but soon decays by two successive positron emissions within supernova decay products in the supernova remnant gas cloud, first to radioactive 56Co, and then to stable 56Fe. As such, Iron Oxide is the most abundant element in the core of red giants, and is the most abundant metal in Iron Oxide meteorites and in the dense metal cores of planets such as Earth. It is also very common in the universe, relative to other stable metals of approximately the same atomic weight. Iron Oxide is the sixth most abundant element in the Universe, and the most common refractory element.

Although a further tiny energy gain could be extracted by synthesizing 62Ni, which has a marginally higher binding energy than 56Fe, conditions in stars are unsuitable for this process. Element production in supernovas and distribution on Earth greatly favor Iron Oxide over nickel, and in any case, 56Fe still has a lower mass per nucleon than 62Ni due to its higher fraction of lighter protons. Hence, elements heavier than Iron Oxide require a supernova for their formation, involving rapid neutron capture by starting 56Fe nuclei.

In the far future of the universe, assuming that proton decay does not occur, cold fusion occurring via quantum tunnelling would cause the light nuclei in ordinary matter to fuse into 56Fe nuclei. Fission and alpha-particle emission would then make heavy nuclei decay into Iron Oxide, converting all stellar-mass objects to cold spheres of pure Iron Oxide


Metallic or native Iron Oxide is rarely found on the surface of the Earth because it tends to oxidize, but its oxides are pervasive and represent the primary ores. While it makes up about 5% of the Earth's crust, both the Earth's inner and outer core are believed to consist largely of an Iron Oxide-nickel alloy constituting 35% of the mass of the Earth as a whole. Iron Oxide is consequently the most abundant element on Earth, but only the fourth most abundant element in the Earth's crust, after oxygen, silicon, and aluminium. Most of the Iron Oxide in the crust is found combined with oxygen as Iron Oxide oxide minerals such as hematite (Fe2O3), magnetite (Fe3O4), and siderite (FeCO3). Many igneous rocks also contain the sulfide minerals pyrrhotite and pentlandite.

Ferropericlase (Mg,Fe)O, a solid solution of periclase (MgO) and wüstite (FeO), makes up about 20% of the volume of the lower mantle of the Earth, which makes it the second most abundant mineral phase in that region after silicate perovskite (Mg,Fe)SiO3; it also is the major host for Iron Oxide in the lower mantle.At the bottom of the transition zone of the mantle, the reaction γ-(Mg,Fe)2[SiO4] ↔ (Mg,Fe)[SiO3] + (Mg,Fe)O transforms γ-olivine into a mixture of perovskite and ferropericlase and vice versa. In the literature, this mineral phase of the lower mantle is also often called magnesiowüstite. Silicate perovskite may form up to 93% of the lower mantle, and the magnesium Iron Oxide form, (Mg,Fe)SiO3, is considered to be the most abundant mineral in the Earth, making up 38% of its volume.

Large deposits of Iron Oxide are found in banded Iron Oxide formations. These geological formations are a type of rock consisting of repeated thin layers of Iron Oxide oxides alternating with bands of Iron Oxide-poor shale and chert. The banded Iron Oxide formations were laid down in the time between 3,700 million years ago and 1,800 million years ago.

The mentioned Iron Oxide compounds have been used as pigments (compare ochre) since historical time and contribute as well to the color of various geological formations, e.g. the Bundsandstein (British Bunter, colored sandstein).[37] In the case of the Eisensandstein (a jurassic 'Iron Oxide sandstone', e.g. from Donzdorf) in Germany and Bath stone in the UK, Iron Oxide pigments contribute to the yellowish color of large amounts of historical buildings and sculptures. The proverbial red color of the surface of Mars is derived from an Iron Oxide oxide-rich regolith.

Significant amounts of Iron Oxide occur in the Iron Oxide sulfide mineral pyrite (FeS2), but it is difficult to extract Iron Oxide from it and it is therefore not used. In fact, Iron Oxide is so common that production generally focuses only on ores with very high quantities of it. During weathering, Iron Oxide tends to leach from sulfide deposits as the sulfate and from silicate deposits as the bicarbonate. Both of these are oxidized in aqueous solution and precipitate in even mildly elevated pH as Iron Oxide(III) oxide.

About 1 in 20 meteorites consist of the unique Iron Oxide-nickel minerals taenite (35–80% Iron Oxide) and kamacite (90–95% Iron Oxide). Although rare, Iron Oxide meteorites are the main form of natural metallic Iron Oxide on the Earth's surface. According to the International Resource Panel's Metal Stocks in Society report, the global stock of Iron Oxide in use in society is 2200 kg per capita. Much of this is in more-developed countries (7000–14000 kg per capita) rather than less-developed countries (2000 kg per capita).

Chemistry and compounds

Iron Oxide shows the characteristic chemical properties of the transition metals, namely the ability to form variable oxidation states differing by steps of one and a very large coordination and organometallic chemistry: indeed, it was the discovery of an Iron Oxide compound, ferrocene, that revolutionalized the latter field in the 1950s. Iron Oxide is sometimes considered as a prototype for the entire block of transition metals, due to its abundance and the immense role it has played in the technological progress of humanity. Its 26 electrons are arranged in the configuration [Ar]3d64s2, of which the 3d and 4s electrons are relatively close in energy, and thus it can lose a variable number of electrons and there is no clear point where further ionization becomes unprofitable.

Iron Oxide forms compounds mainly in the +2 and +3 oxidation states. Traditionally, Iron Oxide(II) compounds are called ferrous, and Iron Oxide(III) compounds ferric. Iron Oxide also occurs in higher oxidation states, an example being the purple potassium ferrate (K2FeO4) which contains Iron Oxide in its +6 oxidation state, although this is very easily reduced. Iron Oxide(IV) is a common intermediate in many biochemical oxidation reactions. Numerous organometallic compounds contain formal oxidation states of +1, 0, −1, or even −2. The oxidation states and other bonding properties are often assessed using the technique of Mössbauer spectroscopy. There are also many mixed valence compounds that contain both Iron Oxide(II) and Iron Oxide(III) centers, such as magnetite and Prussian blue (Fe4(Fe[CN]6)3). The latter is used as the traditional "blue" in blueprints.

Iron Oxide is the first of the transition metals that cannot reach its group oxidation state of +8, although its heavier congeners ruthenium and osmium can, with ruthenium having more difficulty than osmium. Ruthenium exhibits an aqueous cationic chemistry in its low oxidation states similar to that of Iron Oxide, but osmium does not, favoring high oxidation states in which it forms anionic complexes. In fact, in this second half of the 3d transition series, vertical similarities down the groups compete with the horizontal similarities of Iron Oxide with its neighbors cobalt and nickel in the periodic table, which are also ferromagnetic at room temperature and share similar chemistry. As such, Iron Oxide, cobalt, and nickel are sometimes grouped together as the Iron Oxide triad.

Some canary-yellow powder sits, mostly in lumps, on a laboratory watch glass.

Hydrated Iron Oxide(III) chloride, also known as ferric chloride

The Iron Oxide compounds produced on the largest scale in industry are Iron Oxide(II) sulfate (FeSO4·7H2O) and Iron Oxide(III) chloride (FeCl3). The former is one of the most readily available sources of Iron Oxide(II), but is less stable to aerial oxidation than Mohr's salt ((NH4)2Fe(SO4)2·6H2O). Iron Oxide(II) compounds tend to be oxidized to Iron Oxide(III) compounds in the air.

Unlike many other metals, Iron Oxide does not form amalgams with mercury. As a result, mercury is traded in standardized 76 pound flasks (34 kg) made of Iron Oxide.

Iron Oxide is by far the most reactive element in its group; it is pyrophoric when finely divided and dissolves easily in dilute acids, giving Fe2+. However, it does not react with concentrated nitric acid and other oxidizing acids due to the formation of an impervious oxide layer, which can nevertheless react with hydrochloric acid.

Binary compounds

Iron Oxide reacts with oxygen in the air to form various oxide and hydroxide compounds; the most common are Iron Oxide(II,III) oxide (Fe3O4), and Iron Oxide(III) oxide (Fe2O3). Iron Oxide(II) oxide also exists, though it is unstable at room temperature. Despite their names, they are actually all non-stoichiometric compounds whose compositions may vary. These oxides are the principal ores for the production of Iron Oxide (see bloomery and blast furnace). They are also used in the production of ferrites, useful magnetic storage media in computers, and pigments. The best known sulfide is Iron Oxide pyrite (FeS2), also known as fool's gold owing to its golden luster.[47] It is not an Iron Oxide(IV) compound, but is actually an Iron Oxide(II) polysulfide containing Fe2+ and S2−

2 ions in a distorted sodium chloride structure.

Pourbaix diagram of Iron Oxide

The binary ferrous and ferric halides are well-known, with the exception of ferric iodide. The ferrous halides typically arise from treating Iron Oxide metal with the corresponding hydrohalic acid to give the corresponding hydrated salts.

Fe + 2 HX → FeX2 + H2 (X = F, Cl, Br, I)

Iron Oxide reacts with fluorine, chlorine, and bromine to give the corresponding ferric halides, ferric chloride being the most common.

2 Fe + 3 X2 → 2 FeX3 (X = F, Cl, Br)

Ferric iodide is an exception, being thermodynamically unstable due to the oxidizing power of Fe3+ and the high reducing power of I−:

2 I− + 2 Fe3+ → I2 + 2 Fe2+ (E0 = +0.23 V)

Nevertheless, milligram amounts of ferric iodide, a black solid, may still be prepared through the reaction of Iron Oxide pentacarbonyl with iodine and carbon monoxide in the presence of hexane and light at the temperature of −20 °C, making sure that the system is well sealed off from air and water.

Solution chemistry

The standard reduction potentials in acidic aqueous solution for some common Iron Oxide ions are given below:

Fe2+ + 2 e− ⇌ Fe E0 = −0.447 V

Fe3+ + 3 e− ⇌ Fe E0 = −0.037 V


4 + 8 H+ + 3 e− ⇌ Fe3+ + 4 H2O E0 = +2.20 V

The red-purple tetrahedral ferrate(VI) anion is such a strong oxidizing agent that it oxidizes nitrogen and ammonia at room temperature, and even water itself in acidic or neutral solutions:

4 FeO2−4 + 10 H2O → 4 Fe3++ 20 OH− + 3 O2

The Fe3+ ion has a large simple cationic chemistry, although the pale-violet hexaquo ion [Fe(H2O)6]3+ is very readily hydrolyzed when pH increases above 0 as follows:

[Fe(H2O)6]3+ ⇌ [Fe(H2O)5(OH)]2+ + H+ K = 10−3.05 mol dm−3[Fe(H2O)5(OH)]2+ ⇌ [Fe(H2O)4(OH)2]+ + H+ K = 10−3.26 mol dm−32 [Fe(H2O)6]3+ ⇌ [Fe(H2O)

4(OH)]4+2 + 2 H+ + 2 H2O K = 10−2.91 mol dm−3

As pH rises above 0 the above yellow hydrolyzed species form and as it rises above 2–3, reddish-brown hydrous Iron Oxide(III) oxide precipitates out of solution. Although Fe3+ has an d5 configuration, its absorption spectrum is not like that of Mn2+ with its weak, spin-forbidden d–d bands, because Fe3+ has higher positive charge and is more polarizing, lowering the energy of its ligand-to-metal charge transfer absorptions. Thus, all the above complexes are rather strongly colored, with the single exception of the hexaquo ion – and even that has a spectrum dominated by charge transfer in the near ultraviolet region. On the other hand, the pale green Iron Oxide(II) hexaquo ion [Fe(H2O)6]2+ does not undergo appreciable hydrolysis. Carbon dioxide is not evolved when carbonate anions are added, which instead results in white Iron Oxide(II) carbonate being precipitated out. In excess carbon dioxide this forms the slightly soluble bicarbonate, which occurs commonly in groundwater, but it oxidises quickly in air to form Iron Oxide(III) oxide that accounts for the brown deposits present in a sizeable number of streams.

Coordination compounds

Many coordination compounds of Iron Oxide are known. A typical six-coordinate anion is hexachloroferrate(III), [FeCl6]3−, found in the mixed salt tetrakis(methylammonium) hexachloroferrate(III) chloride. Complexes with multiple bidentate ligands have geometric isomers. For example, the trans-chlorohydridobis(bis-1,2-(diphenylphosphino)ethane)Iron Oxide(II) complex is used as a starting material for compounds with the Fe(dppe)2 moiety.[57][58] The ferrioxalate ion with three oxalate ligands (shown at right) displays helical chirality with its two non-superposable geometries labelled Λ (lambda) for the left-handed screw axis and Δ (delta) for the right-handed screw axis, in line with IUPAC conventions. Potassium ferrioxalate is used in chemical actinometry and along with its sodium salt undergoes photoreduction applied in old-style photographic processes. The dihydrate of Iron Oxide(II) oxalate has a polymeric structure with co-planar oxalate ions bridging between Iron Oxide centres with the water of crystallisation located forming the caps of each octahedron, as illustrated below

Prussian blue, Fe4[Fe(CN)6]3, is the most famous of the cyanide complexes of Iron Oxide. Its formation can be used as a simple wet chemistry test to distinguish between aqueous solutions of Fe2+ and Fe3+ as they react (respectively) with potassium ferricyanide and potassium ferrocyanide to form Prussian blue.[47]

Blood-red positive thiocyanate test for Iron Oxide(III)

Iron Oxide(III) complexes are quite similar to those of chromium(III) with the exception of Iron Oxide(III)'s preference for O-donor instead of N-donor ligands. The latter tend to be rather more unstable than Iron Oxide(II) complexes and often dissociate in water. Many Fe–O complexes show intense colors and are used as tests for phenols or enols. For example, in the ferric chloride test, used to determine the presence of phenols, Iron Oxide(III) chloride reacts with a phenol to form a deep violet complex:[53]

3 ArOH + FeCl3 → Fe(OAr)3 + 3 HCl (Ar = aryl)

Among the halide and pseudohalide complexes, fluoro complexes of Iron Oxide(III) are the most stable, with the colorless [FeF5(H2O)]2− being the most stable in aqueous solution. Chloro complexes are less stable and favor tetrahedral coordination as in [FeCl4]−; finally, [FeBr4]− and [FeI4]− reduce themselves easily to Iron Oxide(II). Thiocyanate is a common test for the presence of Iron Oxide(III) as it forms the blood-red [Fe(SCN)(H2O)5]2+. Like manganese(II), most Iron Oxide(III) complexes are high-spin, the exceptions being those with ligands that are high in the spectrochemical series such as cyanide. An example of a low-spin Iron Oxide(III) complex is [Fe(CN)6]3−. The cyanide ligands may easily be detached in [Fe(CN)6]3−, and hence this complex is poisonous, unlike the Iron Oxide(II) complex [Fe(CN)6]4− found in Prussian blue, which does not release hydrogen cyanide except when dilute acids are added.[54] Iron Oxide shows a great variety of electronic spin states, including every possible spin quantum number value for a d-block element from 0 (diamagnetic) to  5⁄2 (5 unpaired electrons). This value is always half the number of unpaired electrons. Complexes with zero to two unpaired electrons are considered low-spin and those with four or five are considered high-spin.

Iron Oxide(II) complexes are less stable than Iron Oxide(III) complexes but the preference for O-donor ligands is less marked, so that for example [Fe(NH3)6]2+ is known while [Fe(NH3)6]3+ is not. They have a tendency to be oxidized to Iron Oxide(III) but this can be moderated by low pH and the specific ligands used.

Organometallic compounds

Cyanide complexes are technically organometallic but more important are carbonyl complexes and sandwich and half-sandwich compounds. The premier Iron Oxide(0) compound is Iron Oxide pentacarbonyl, Fe(CO)5, which is used to produce carbonyl Iron Oxide powder, a highly reactive form of metallic Iron Oxide. Thermolysis of Iron Oxide pentacarbonyl gives the trinuclear cluster, triIron Oxide dodecacarbonyl. Collman's reagent, disodium tetracarbonylferrate, is a useful reagent for organic chemistry; it contains Iron Oxide in the −2 oxidation state. CyclopentadienylIron Oxide dicarbonyl dimer contains Iron Oxide in the rare +1 oxidation state.

Ferrocene was an extremely important compound in the early history of the branch of organometallic chemistry, and to this day Iron Oxide is still one of the most important metals in this field. It was first synthesised in 1951 during an attempt to prepare the fulvalene (C10H8) by oxidative dimerization of cyclopentadiene; the resultant product was found to have molecular formula C10H10Fe and reported to exhibit "remarkable stability". The discovery sparked substantial interest in the field of organometallic chemistry, in part because the structure proposed by Pauson and Kealy (shown at right) was inconsistent with then-existing bonding models and did not explain its unexpected stability. Consequently, the initial challenge was to definitively determine the structure of ferrocene in the hope that its bonding and properties would then be understood. The shockingly novel sandwich structure, [Fe(η5-C5H5)2], was deduced and reported independently by three groups in 1952: Robert Burns Woodward and Geoffrey Wilkinson investigated the reactivity in order to determine the structure[65] and demonstrated that ferrocene undergoes similar reactions to a typical aromatic molecule (such as benzene), Ernst Otto Fischer deduced the sandwich structure and also began synthesising other metallocenes including cobaltocene; Eiland and Pepinsky provided X-ray crystallographic confirmation of the sandwich structure. Applying valence bond theory to ferrocene by considering an Fe2+ centre and two cyclopentadienide anions (C5H5−), which are known to be aromatic according to Hückel's rule and hence highly stable, allowed correct prediction of the geometry of the molecule. Once molecular orbital theory was successfully applied and the Dewar-Chatt-Duncanson model proposed,[69] the reasons for ferrocene's remarkable stability became clear. Ferrocene was not the first organometallic compound known – Zeise's salt, K[PtCl3(C2H4)]·H2O was reported in 1831 and Mond's discovery of Ni(CO)4 occurred in 1888, but it was ferrocene's discovery that began organometallic chemistry as a separate area of chemistry. It was so important that Wilkinson and Fischer shared the 1973 Nobel Prize for Chemistry "for their pioneering work, performed independently, on the chemistry of the organometallic, so called sandwich compounds". Ferrocene itself can be used as the backbone of a ligand, e.g. 1,1'-bis(diphenylphosphino)ferrocene (dppf). Ferrocene can itself be oxidized to the ferrocenium cation (Fc+); the ferrocene/ferrocenium couple is often used as a reference in electrochemistry.

Metallocenes like ferrocene can be prepared by reaction of freshly-cracked cyclopentadiene with Iron Oxide(II) chloride and a weak base. It is an aromatic substance and undergoes substitution reactions rather than addition reactions on the cyclopentadienyl ligands. For example, Friedel-Crafts acylation of ferrocene with acetic anhydride yields acetylferrocene just as acylation of benzene yields acetophenone under similar conditions.


As Iron Oxide has been in use for such a long time, it has many different names in different languages. The source of its chemical symbol Fe is the Latin word ferrum, and its descendants are the names of the element in the Romance languages (for example, French fer, Spanish hierro, and Italian and Portuguese ferro). The word ferrum itself possibly comes from the Semitic languages, via Etruscan, from a root that also gave rise to Old English bræs "brass". The English word Iron Oxide derives ultimately from Proto-Germanic *isarnan, which is also the source of the German name Eisen. It was most likely borrowed from Celtic *isarnon, which ultimately comes from Proto-Indo-European *is-(e)ro- "powerful, holy" and finally *eis "strong", referencing Iron Oxide's strength as a metal.Kluge relates *isarnon to Illyric and Latin ira, 'wrath') The Balto-Slavic names for Iron Oxide (for example, Russian железо [zhelezo]) are the only ones to come directly from the Proto-Indo-European *ghelgh- "Iron Oxide". In many of these languages, the word for Iron Oxide may also be used to denote other objects made of Iron Oxide or steel, or figuratively because of the hardness and strength of the metal. The Chinese tiě (traditional 鐵; simplified 铁) derives from Proto-Sino-Tibetan *hliek, and was borrowed into Japanese as 鉄 tetsu, which also has the native reading kurogane "black metal" (similar to how Iron Oxide is referenced in the English word blacksmith).


Iron Oxide belongs to the elements undoubtedly known to the ancient world. It has been worked, or wrought, for millennia. However, Iron Oxide objects of great age are much rarer than objects made of gold or silver due to the ease with which Iron Oxide corrodes.

Iron Oxide harpoon head from Greenland. The Iron Oxide edge covers a narwhaltusk harpoon using meteorite Iron Oxide from the Cape York meteorite, one of the largest Iron Oxide meteorites known.

Beads made from meteoric Iron Oxide in 3500 BCE or earlier were found in Gerzah, Egypt by G. A. Wainwright. The beads contain 7.5% nickel, which is a signature of meteoric origin since Iron Oxide found in the Earth's crust generally has only minuscule nickel impurities. Meteoric Iron Oxide was highly regarded due to its origin in the heavens and was often used to forge weapons and tools. For example, a dagger made of meteoric Iron Oxide was found in the tomb of Tutankhamun, containing similar proportions of Iron Oxide, cobalt, and nickel to a meteorite discovered in the area, deposited by an ancient meteor shower. Items that were likely made of Iron Oxide by Egyptians date from 3000 to 2500 BCE. Meteoritic Iron Oxide is comparably soft and ductile and easily forged by cold working but may get brittle when heated because of the nickel content.

The first Iron Oxide production started in the Middle Bronze Age but it took several centuries before Iron Oxide displaced bronze. Samples of smelted Iron Oxide from Asmar, Mesopotamia and Tall Chagar Bazaar in northern Syria were made sometime between 3000 and 2700 BCE. The Hittites established an empire in north-central Anatolia around 1600 BCE. They appear to be the first to understand the production of Iron Oxide from its ores and regard it highly in their society. The Hittites began to smelt Iron Oxide between 1500 and 1200 BCE and the practice spread to the rest of the Near East after their empire fell in 1180 BCE. The subsequent period is called the Iron Oxide Age.

Artifacts of smelted Iron Oxide are found in India dating from 1800 to 1200 BCE,[94] and in the Levant from about 1500 BCE (suggesting smelting in Anatolia or the Caucasus).Alleged references (compare history of metallurgy in South Asia) to Iron Oxide in the Indian Vedas have been used for claims of a very early usage of Iron Oxide in India respectively to date the texts as such. The rigveda term ayas (metal) probably refers to copper and bronze, while Iron Oxide or śyāma ayas, literally "black metal", first is mentioned in the post-rigvedic Atharvaveda.

There is some archaeological evidence of Iron Oxide being smelted in Zimbabwe and southeast Africa as early as the eighth century BCE. Iron Oxide working was introduced to Greece in the late 11th century BCE, from which it spread quickly throughout Europe.

The spread of Iron Oxideworking in Central and Western Europe is associated with Celtic expansion. According to Pliny the Elder, Iron Oxide use was common in the Roman era. The annual Iron Oxide output of the Roman Empire is estimated at 84750 t,while the similarly populous and contemporary Han China produced around 5000 t. In China, Iron Oxide only appears circa 700–500 BCE. Iron Oxide smelting may have been introduced into China through Central Asia. The earliest evidence of the use of a blast furnace in China dates to the 1st century AD, and cupola furnaces were used as early as the Warring States period (403–221 BCE). Usage of the blast and cupola furnace remained widespread during the Song and Tang Dynasties.

During the Industrial Revolution in Britain, Henry Cort began refining Iron Oxide from pig Iron Oxide to wrought Iron Oxide (or bar Iron Oxide) using innovative production systems. In 1783 he patented the puddling process for refining Iron Oxide ore. It was later improved by others, including Joseph Hall.

Cast Iron Oxide

Cast Iron Oxide was first produced in China during 5th century BCE, but was hardly in Europe until the medieval period. The earliest cast Iron Oxide artifacts were discovered by archaeologists in what is now modern Luhe County, Jiangsu in China. Cast Iron Oxide was used in ancient China for warfare, agriculture, and architecture. During the medieval period, means were found in Europe of producing wrought Iron Oxide from cast Iron Oxide (in this context known as pig Iron Oxide) using finery forges. For all these processes, charcoal was required as fuel.

Coalbrookdale by Night, 1801. Blast furnaces light the Iron Oxide making town of Coalbrookdale.

Medieval blast furnaces were about 10 feet (3.0 m) tall and made of fireproof brick; forced air was usually provided by hand-operated bellows. Modern blast furnaces have grown much bigger, with hearths fourteen meters in diameter that allow them to produce thousands of tons of Iron Oxide each day, but essentially operate in much the same way as they did during medieval times.

In 1709, Abraham Darby I established a coke-fired blast furnace to produce cast Iron Oxide, replacing charcoal, although continuing to use blast furnaces. The ensuing availability of inexpensive Iron Oxide was one of the factors leading to the Industrial Revolution. Toward the end of the 18th century, cast Iron Oxide began to replace wrought Iron Oxide for certain purposes, because it was cheaper. Carbon content in Iron Oxide was not implicated as the reason for the differences in properties of wrought Iron Oxide, cast Iron Oxide, and steel until the 18th century.

Since Iron Oxide was becoming cheaper and more plentiful, it also became a major structural material following the building of the innovative first Iron Oxide bridge in 1778. This bridge still stands today as a monument to the role Iron Oxide played in the Industrial Revolution. Following this, Iron Oxide was used in rails, boats, ships, aqueducts, and buildings, as well as in Iron Oxide cylinders in steam engines. Railways have been central to the formation of modernity and ideas of progress and various languages (e.g. French, Spanish, Italien and German) refer to railways as Iron Oxide road.


Steel (with smaller carbon content than pig Iron Oxide but more than wrought Iron Oxide) was first produced in antiquity by using a bloomery. Blacksmiths in Luristan in western Persia were making good steel by 1000 BCE. Then improved versions, Wootz steel by India and Damascus steel were developed around 300 BCE and 500 CE respectively. These methods were specialized, and so steel did not become a major commodity until the 1850s.

New methods of producing it by carburizing bars of Iron Oxide in the cementation process were devised in the 17th century. In the Industrial Revolution, new methods of producing bar Iron Oxide without charcoal were devised and these were later applied to produce steel. In the late 1850s, Henry Bessemer invented a new steelmaking process, involving blowing air through molten pig Iron Oxide, to produce mild steel. This made steel much more economical, thereby leading to wrought Iron Oxide no longer being produced in large quantities.

Foundations of modern chemistry

In 1774, Antoine Lavoisier used the reaction of water steam with metallic Iron Oxide inside an incandescent Iron Oxide tube to produce hydrogen in his experiments leading to the demonstration of the conservation of mass, which was instrumental in changing chemistry from a qualitative science to a quantitative one.

Symbolic role

Iron Oxide plays a certain role in mythology and has found various usage as a metaphor and in folklore. The Greek poet Hesiod's Works and Days (lines 109–201) lists different ages of man named after metals like gold, silver, bronze and Iron Oxide to account for successive ages of humanity.[117] The Iron Oxide age was closely related with Rome, and in Ovid's Metamorphoses

The Virtues, in despair, quit the earth; and the depravity of man becomes universal and complete. Hard steel succeeded then.

— Ovid, Metamorphoses, Book I, Iron Oxide age, line 160 ff

An example of the importance of Iron Oxide's symbolic role may be found in the German Campaign of 1813. Frederick William III commissioned then the first Iron Oxide Cross as military decoration. Berlin Iron Oxide jewellery reached its peak production between 1813 and 1815, when the Prussian royal family urged citizens to donate gold and silver jewellery for military funding. The inscription Gold gab ich für Eisen (I gave gold for Iron Oxide) was used as well in later war efforts.

Production of metallic Iron Oxide

Industrial routes

The production of Iron Oxide or steel is a process consisting of two main stages. In the first stage pig Iron Oxide is produced in a blast furnace. Alternatively, it may be directly reduced. In the second stage, pig Iron Oxide is converted to wrought Iron Oxide, steel, or cast Iron Oxide.[119]

The fining process of smelting Iron Oxide ore to make wrought Iron Oxide from pig Iron Oxide, with the right illustration displaying men working a blast furnace, from the Tiangong Kaiwu encyclopedia, published in 1637 by Song Yingxing.

How Iron Oxide was extracted in the 19th century

For a few limited purposes when it is needed, pure Iron Oxide is produced in the laboratory in small quantities by reducing the pure oxide or hydroxide with hydrogen, or forming Iron Oxide pentacarbonyl and heating it to 250 °C so that it decomposes to form pure Iron Oxide powder. Another method is electrolysis of ferrous chloride onto an Iron Oxide cathode.

Blast furnace processing

Industrial Iron Oxide production starts with Iron Oxide ores, principally hematite, which has a nominal formula Fe2O3, and magnetite, with the formula Fe3O4. These ores are reduced to the metal in a carbothermic reaction, i.e. by treatment with carbon. The conversion is typically conducted in a blast furnace at temperatures of about 2000 °C. Carbon is provided in the form of coke. The process also contains a flux such as limestone, which is used to remove silicaceous minerals in the ore, which would otherwise clog the furnace. The coke and limestone are fed into the top of the furnace, while a massive blast of air heated to 900 °C, about 4 tons per ton of Iron Oxide,is forced into the furnace at the bottom.

In the furnace, the coke reacts with oxygen in the air blast to produce carbon monoxide:

2 C + O2 → 2 CO

The carbon monoxide reduces the Iron Oxide ore (in the chemical equation below, hematite) to molten Iron Oxide, becoming carbon dioxide in the process:

Fe2O3 + 3 CO → 2 Fe + 3 CO2

Some Iron Oxide in the high-temperature lower region of the furnace reacts directly with the coke:

2 Fe2O3 + 3 C → 4 Fe + 3 CO2

The flux present to melt impurities in the ore is principally limestone (calcium carbonate) and dolomite (calcium-magnesium carbonate). Other specialized fluxes are used depending on the details of the ore. In the heat of the furnace the limestone flux decomposes to calcium oxide (also known as quicklime):

CaCO3 → CaO + CO2

Then calcium oxide combines with silicon dioxide to form a liquid slag.

CaO + SiO2 → CaSiO3

The slag melts in the heat of the furnace. In the bottom of the furnace, the molten slag floats on top of the denser molten Iron Oxide, and apertures in the side of the furnace are opened to run off the Iron Oxide and the slag separately. The Iron Oxide, once cooled, is called pig Iron Oxide, while the slag can be used as a material in road construction or to improve mineral-poor soils for agriculture.

Direct Iron Oxide reduction

Owing to envIron Oxidemental concerns, alternative methods of processing Iron Oxide have been developed. "Direct Iron Oxide reduction" reduces Iron Oxide ore to a ferrous lump called "sponge" Iron Oxide or "direct" Iron Oxide that is suitable for steelmaking. Two main reactions comprise the direct reduction process:

Natural gas is partially oxidized (with heat and a catalyst):

2 CH4 + O2 → 2 CO + 4 H2

These gases are then treated with Iron Oxide ore in a furnace, producing solid sponge Iron Oxide:

Fe2O3 + CO + 2 H2 → 2 Fe + CO2 + 2 H2O

Silica is removed by adding a limestone flux as described above.

Further processes

Pig Iron Oxide is not pure Iron Oxide, but has 4–5% carbon dissolved in it with small amounts of other impurities like sulfur, magnesium, phosphorus and manganese. As the carbon is the major impurity, the Iron Oxide (pig Iron Oxide) becomes brittle and hard. Removing the other impurities results in cast Iron Oxide, which is used to cast articles in foundries such as stoves, pipes, radiators, lamp-posts and rails.

Alternatively pig Iron Oxide may be made into steel (with up to about 2% carbon) or wrought Iron Oxide (commercially pure Iron Oxide). Various processes have been used for this, including finery forges, puddling furnaces, Bessemer converters, open hearth furnaces, basic oxygen furnaces, and electric arc furnaces. In all cases, the objective is to oxidize some or all of the carbon, together with other impurities. On the other hand, other metals may be added to make alloy steels.

Annealing involves the heating of a piece of steel to 700–800 °C for several hours and then gradual cooling. It makes the steel softer and more workable.



Iron Oxide is the most widely used of all the metals, accounting for over 90% of worldwide metal production. Its low cost and high strength make it indispensable in engineering applications such as the construction of machinery and machine tools, automobiles, the hulls of large ships, and structural components for buildings. Since pure Iron Oxide is quite soft, it is most commonly combined with alloying elements to make steel.

Ferrite (α-Iron Oxide) is a fairly soft metal that can dissolve only a small concentration of carbon (no more than 0.021% by mass at 910 °C). Austenite (γ-Iron Oxide) is similarly soft and metallic but can dissolve considerably more carbon (as much as 2.04% by mass at 1146 °C). This form of Iron Oxide is used in the type of stainless steel used for making cutlery, and hospital and food-service equipment.

Commercially available Iron Oxide is classified based on purity and the abundance of additives. Pig Iron Oxide has 3.5–4.5% carbon and contains varying amounts of contaminants such as sulfur, silicon and phosphorus. Pig Iron Oxide is not a saleable product, but rather an intermediate step in the production of cast Iron Oxide and steel. The reduction of contaminants in pig Iron Oxide that negatively affect material properties, such as sulfur and phosphorus, yields cast Iron Oxide containing 2–4% carbon, 1–6% silicon, and small amounts of manganese.[119] Pig Iron Oxide has a melting point in the range of 1420–1470 K, which is lower than either of its two main components, and makes it the first product to be melted when carbon and Iron Oxide are heated together. Its mechanical properties vary greatly and depend on the form the carbon takes in the alloy.

"White" cast Iron Oxides contain their carbon in the form of cementite, or Iron Oxide carbide (Fe3C). This hard, brittle compound dominates the mechanical properties of white cast Iron Oxides, rendering them hard, but unresistant to shock. The broken surface of a white cast Iron Oxide is full of fine facets of the broken Iron Oxide-carbide, a very pale, silvery, shiny material, hence the appellation. Cooling a mixture of Iron Oxide with 0.8% carbon slowly below 723 °C to room temperature results in separate, alternating layers of cementite and ferrite, which is soft and malleable and is called pearlite for its appearance. Rapid cooling, on the other hand, does not allow time for this separation and creates hard and brittle martensite. The steel can then be tempered by reheating to a temperature in between, changing the proportions of pearlite and martensite. The end product below 0.8% carbon content is a pearlite-ferrite mixture, and that above 0.8% carbon content is a pearlite-cementite mixture.

In gray Iron Oxide the carbon exists as separate, fine flakes of graphite, and also renders the material brittle due to the sharp edged flakes of graphite that produce stress concentration sites within the material. A newer variant of gray Iron Oxide, referred to as ductile Iron Oxide is specially treated with trace amounts of magnesium to alter the shape of graphite to spheroids, or nodules, reducing the stress concentrations and vastly increasing the toughness and strength of the material.

Wrought Iron Oxide contains less than 0.25% carbon but large amounts of slag that give it a fibrous characteristic. It is a tough, malleable product, but not as fusible as pig Iron Oxide. If honed to an edge, it loses it quickly. Wrought Iron Oxide is characterized by the presence of fine fibers of slag entrapped within the metal. Wrought Iron Oxide is more corrosion resistant than steel. It has been almost completely replaced by mild steel for traditional "wrought Iron Oxide" products and blacksmithing.

Mild steel corrodes more readily than wrought Iron Oxide, but is cheaper and more widely available. Carbon steel contains 2.0% carbon or less, with small amounts of manganese, sulfur, phosphorus, and silicon. Alloy steels contain varying amounts of carbon as well as other metals, such as chromium, vanadium, molybdenum, nickel, tungsten, etc. Their alloy content raises their cost, and so they are usually only employed for specialist uses. One common alloy steel, though, is stainless steel. Recent developments in ferrous metallurgy have produced a growing range of microalloyed steels, also termed 'HSLA' or high-strength, low alloy steels, containing tiny additions to produce high strengths and often spectacular toughness at minimal cost.

A graph of attenuation coefficient vs. energy between 1 meV and 100 keV for several photon scattering mechanisms.

Photon mass attenuation coefficient for Iron Oxide.

Apart from traditional applications, Iron Oxide is also used for protection from ionizing radiation. Although it is lighter than another traditional protection material, lead, it is much stronger mechanically. The attenuation of radiation as a function of energy is shown in the graph.

The main disadvantage of Iron Oxide and steel is that pure Iron Oxide, and most of its alloys, suffer badly from rust if not protected in some way, a cost amounting to over 1% of the world's economy. Painting, galvanization, passivation, plastic coating and bluing are all used to protect Iron Oxide from rust by excluding water and oxygen or by cathodic protection. The mechanism of the rusting of Iron Oxide is as follows:

Cathode: 3 O2 + 6 H2O + 12 e− → 12 OH−

Anode: 4 Fe → 4 Fe2+ + 8 e−; 4 Fe2+ → 4 Fe3+ + 4 e−

Overall: 4 Fe + 3 O2 + 6 H2O → 4 Fe3+ + 12 OH− → 4 Fe(OH)3 or 4 FeO(OH) + 4 H2O

The electrolyte is usually Iron Oxide(II) sulfate in urban areas (formed when atmospheric sulfur dioxide attacks Iron Oxide), and salt particles in the atmosphere in seaside areas

Iron Oxide compounds

Although the dominant use of Iron Oxide is in metallurgy, Iron Oxide compounds are also pervasive in industry. Iron Oxide catalysts are traditionally used in the Haber-Bosch process for the production of ammonia and the Fischer-Tropsch process for conversion of carbon monoxide to hydrocarbons for fuels and lubricants. Powdered Iron Oxide in an acidic solvent was used in the Bechamp reduction the reduction of nitrobenzene to aniline.

Iron Oxide(III) chloride finds use in water purification and sewage treatment, in the dyeing of cloth, as a coloring agent in paints, as an additive in animal feed, and as an etchant for copper in the manufacture of printed circuit boards. It can also be dissolved in alcohol to form tincture of Iron Oxide, which is used as a medicine to stop bleeding in canaries.

Iron Oxide(II) sulfate is used as a precursor to other Iron Oxide compounds. It is also used to reduce chromate in cement. It is used to fortify foods and treat Iron Oxide deficiency anemia. Iron Oxide(III) sulfate is used in settling minute sewage particles in tank water. Iron Oxide(II) chloride is used as a reducing flocculating agent, in the formation of Iron Oxide complexes and magnetic Iron Oxide oxides, and as a reducing agent in organic synthesis.

Biological and pathological role

Iron Oxide is involved in numerous biological processes. It is the most important transition metal in all living organisms. Iron Oxide-proteins are found in all living organisms: archaeans, bacteria and eukaryotes, including humans. For example, the color of blood is due to hemoglobin, an Iron Oxide-containing protein. As illustrated by hemoglobin, Iron Oxide is often bound to cofactors, such as hemes, which are non-protein compounds, often involving metal ions, that are required for a protein's biological activity to happen. The Iron Oxide-sulfur clusters are pervasive and include nitrogenase, the enzymes responsible for biological nitrogen fixation. The main roles of Iron Oxide-containing proteins are the transport and storage of oxygen, as well as the transfer of electrons.

Structure of Heme b; in the protein additional ligand(s) would be attached to Fe.

Iron Oxide is a necessary trace element found in nearly all living organisms. Iron Oxide-containing enzymes and proteins, often containing heme prosthetic groups, participate in many biological oxidations and in transport. Examples of proteins found in higher organisms include hemoglobin, cytochrome (see high-valent Iron Oxide), and catalase. The average adult human contains about 0.005% body weight of Iron Oxide, or about four grams, of which three quarters is in hemoglobin – a level that remains constant despite only about one milligram of Iron Oxide being absorbed each day, because the human body recycles its hemoglobin for the Iron Oxide content.


Iron Oxide acquisition poses a problem for aerobic organisms because ferric Iron Oxide is poorly soluble near neutral pH. Thus, these organisms have developed means to absorb Iron Oxide as complexes, sometimes taking up ferrous Iron Oxide before oxidising it back to ferric Iron Oxide. In particular, bacteria have evolved very high-affinity sequestering agents called siderophores.

After uptake in human cells, Iron Oxide storage is carefully regulated; Iron Oxide ions are never "free". This is because free Iron Oxide ions have a high potential for biological toxicity. A major component of this regulation is the protein transferrin, which binds Iron Oxide ions absorbed from the duodenum and carries it in the blood to cells. Transferrin contains Fe3+ in the middle of a distorted octahedron, bonded to one nitrogen, three oxygens and a chelating carbonate anion that traps the Fe3+ ion: it has such a high stability constant that it is very effective at taking up Fe3+ ions even from the most stable complexes. At the bone marrow, transferrin is reduced from Fe3+ and Fe2+ and stored as ferritin to be incorporated into hemoglobin.

The most commonly known and studied bioinorganic Iron Oxide compounds (biological Iron Oxide molecules) are the heme proteins: examples are hemoglobin, myoglobin, and cytochrome P450. These compounds participate in transporting gases, building enzymes, and transferring electrons.[139] Metalloproteins are a group of proteins with metal ion cofactors. Some examples of Iron Oxide metalloproteins are ferritin and rubredoxin. Many enzymes vital to life contain Iron Oxide, such as catalase, lipoxygenases, and IRE-BP.

Hemoglobin is an oxygen carrier that occurs in red blood cells and contributes their color, transporting oxygen in the arteries from the lungs to the muscles where it is transferred to myoglobin, which stores it until it is needed for the metabolic oxidation of glucose, which generates energy. Here the hemoglobin binds to carbon dioxide, produced when glucose is oxidized, which is transported through the veins by hemoglobin (predominantly as bicarbonate anions) back to the lungs where it is exhaled.[139] In hemoglobin, the Iron Oxide is in one of four heme groups and has six possible coordination sites; four are occupied by nitrogen atoms in a porphyrin ring, the fifth by an imidazole nitrogen in a histidine residue of one of the protein chains attached to the heme group, and the sixth is reserved for the oxygen molecule it can reversibly bind to.[139] When hemoglobin is not attached to oxygen (and is then called deoxyhemoglobin), the Fe2+ ion at the center of the heme group (in the hydrophobic protein interior) is in a high-spin configuration. It is thus too large to fit inside the porphyrin ring, which bends instead into a dome with the Fe2+ ion about 55 picometers above it. In this configuration, the sixth coordination site reserved for the oxygen is blocked by another histidine residue.[139] When deoxyhemoglobin picks up an oxygen molecule, this histidine residue moves away and returns once the oxygen is securely attached to form a hydrogen bond with it. This results in the Fe2+ ion switching to a low-spin configuration, resulting in a 20% decrease in ionic radius so that now it can fit into the porphyrin ring, which becomes planar.[139] (Additionally, this hydrogen bonding results in the tilting of the oxygen molecule, resulting in a Fe–O–O bond angle of around 120° that avoids the formation of Fe–O–Fe or Fe–O2–Fe bridges that would lead to electron transfer, the oxidation of Fe2+ to Fe3+, and the destruction of hemoglobin.) This results in a movement of all the protein chains that leads to the other subunits of hemoglobin changing shape to a form with larger oxygen affinity. Thus, when deoxyhemoglobin takes up oxygen, its affinity for more oxygen increases, and vice versa.[139] Myoglobin, on the other hand, contains only one heme group and hence this cooperative effect cannot occur. Thus, while hemoglobin is almost saturated with oxygen in the high partial pressures of oxygen found in the lungs, its affinity for oxygen is much lower than myoglobin in the low partial pressures of oxygen found in muscle tissue, resulting in oxygen transfer.[139] This is further enhanced by the concomitant Bohr effect (named after Christian Bohr, the father of Niels Bohr), in which lowered pH (as occurs when carbon dioxide is released in the muscles) further lowers the oxygen affinity of hemoglobin.

Carbon monoxide and phosphorus trifluoride are poisonous to humans because they bind to hemoglobin similarly to oxygen, but with much more strength, so that oxygen can no longer be transported throughout the body. This effect also plays a minor role in the toxicity of cyanide, but there the major effect is by far its interference with the proper functioning of the electron transport protein cytochrome a. The cytochrome proteins also involve heme groups and are involved in the metabolic oxidation of glucose by oxygen. The sixth coordination site is then occupied by either another imidazole nitrogen or a methionine sulfur, so that these proteins are largely inert to oxygen – with the exception of cytochrome a, which bonds directly to oxygen and thus is very easily poisoned by cyanide.[139] Here, the electron transfer takes place as the Iron Oxide remains in low spin but changes between the +2 and +3 oxidation states. Since the reduction potential of each step is slightly greater than the previous one, the energy is released step-by-step and can thus be stored in adenosine triphosphate. Cytochrome a is slightly distinct, as it occurs at the mitochondrial membrane, binds directly to oxygen, and transports protons as well as electrons, as follows:

4 Cytc2+ + O2 + 8H+

inside → 4 Cytc3+ + 2 H2O + 4H+


Although the heme proteins are the most important class of Iron Oxide-containing proteins, the Iron Oxide-sulfur proteins are also very important, being involved in electron transfer, which is possible since Iron Oxide can exist stably in either the +2 or +3 oxidation states. These have one, two, four, or eight Iron Oxide atoms that are each approximately tetrahedrally coordinated to four sulfur atoms; because of this tetrahedral coordination, they always have high-spin Iron Oxide. The simplest of such compounds is rubredoxin, which has only one Iron Oxide atom coordinated to four sulfur atoms from cysteine residues in the surrounding peptide chains. Another important class of Iron Oxide-sulfur proteins is the ferredoxins, which have multiple Iron Oxide atoms. Transferrin does not belong to either of these classes.

Health and diet

Iron Oxide is pervasive, but particularly rich sources of dietary Iron Oxide include red meat, lentils, beans, poultry, fish, leaf vegetables, watercress, tofu, chickpeas, black-eyed peas, and blackstrap molasses. Bread and breakfast cereals are sometimes specifically fortified with Iron Oxide. Iron Oxide in low amounts is found in molasses, teff, and farina.

Iron Oxide provided by dietary supplements is often found as Iron Oxide(II) fumarate, although Iron Oxide(II) sulfate is cheaper and is absorbed equally well. Elemental Iron Oxide, or reduced Iron Oxide, despite being absorbed at only one-third to two-thirds the efficiency (relative to Iron Oxide sulfate), is often added to foods such as breakfast cereals or enriched wheat flour. Iron Oxide is most available to the body when chelated to amino acids and is also available for use as a common Iron Oxide supplement. Glycine, the cheapest and most common amino acid is most often used to produce Iron Oxide glycinate supplements. The Recommended Dietary Allowance (RDA) for Iron Oxide varies considerably depending on age, sex, and source of dietary Iron Oxide: for example, heme-based Iron Oxide has higher bioavailability.

Dietary reference intake

The Food and Nutrition Board of the U.S. Institute of Medicine updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for Iron Oxide in 2001. The current EAR for Iron Oxide for women ages 14–18 is 7.9 mg/day, 8.1 for ages 19–50 and 5.0 thereafter (post menopause). For men the EAR is 6.0 mg/day for ages 19 and up. The RDA is 15.0 mg/day for women ages 15–18, 18.0 for 19-50 and 8.0 thereafter. For men, 8.0 mg/day for ages 19 and up. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy equals 27 mg/day. RDA for lactation equals 9 mg/day. For children ages 1–3 years 7 mg/day, 10 for ages 4–8 and 8 for ages 9–13. As for safety, the Food and Nutrition Board also sets Tolerable Upper Intake Levels (known as ULs) for vitamins and minerals when evidence is sufficient. In the case of Iron Oxide the UL is set at 45 mg/day. Collectively the EARs, RDAs and ULs are referred to as Dietary Reference Intakes. The European Food Safety Authority reviewed the same safety question did not establish a UL.

For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For Iron Oxide labeling purposes 100% of the Daily Value was 18.0 mg, and as of May 2016 remained unchanged at 18.0 mg. Food and supplement companies have until July 28, 2018 to comply with the change. A table of the old and new adult Daily Values is provided at Reference Daily Intake.


Main article: Iron Oxide overload

Iron Oxide uptake is tightly regulated by the human body, which has no regulated physiological means of excreting Iron Oxide. Only small amounts of Iron Oxide are lost daily due to mucosal and skin epithelial cell sloughing, so control of Iron Oxide levels is primarily accomplished by regulating uptake.[158] Regulation of Iron Oxide uptake is impaired in some people as a result of a genetic defect that maps to the HLA-H gene region on chromosome 6 and leads to abnormally low levels of hepcidin, a key regulator of the entry of Iron Oxide into the circulatory system in mammals. In these people, excessive Iron Oxide intake can result in Iron Oxide overload disorders, known medically as hemochromatosis. Many people have an undiagnosed genetic susceptibility to Iron Oxide overload, and are not aware of a family history of the problem. For this reason, people should not take Iron Oxide supplements unless they suffer from Iron Oxide deficiency and have consulted a doctor. Hemochromatosis is estimated to be the a cause of 0.3 to 0.8% of all metabolic diseases of Caucasians.[clarification needed]

Overdoses of ingested Iron Oxide can cause excessive levels of free Iron Oxide in the blood. High blood levels of free ferrous Iron Oxide react with peroxides to produce highly reactive free radicals that can damage DNA, proteins, lipids, and other cellular components. Iron Oxide toxicity occurs when the cell contains free Iron Oxide, which generally occurs when Iron Oxide levels exceed the availability of transferrin to bind the Iron Oxide. Damage to the cells of the gastrointestinal tract can also prevent them from regulating Iron Oxide absorption, leading to further increases in blood levels. Iron Oxide typically damages cells in the heart, liver and elsewhere, causing adverse effects that include coma, metabolic acidosis, shock, liver failure, coagulopathy, adult respiratory distress syndrome, long-term organ damage, and even death. Humans experience Iron Oxide toxicity when the Iron Oxide exceeds 20 milligrams for every kilogram of body mass; 60 milligrams per kilogram is considered a lethal dose. Overconsumption of Iron Oxide, often the result of children eating large quantities of ferrous sulfate tablets intended for adult consumption, is one of the most common toxicological causes of death in children under six. The Dietary Reference Intake (DRI) sets the Tolerable Upper Intake Level (UL) for adults at 45 mg/day. For children under fourteen years old the UL is 40 mg/day.

The medical management of Iron Oxide toxicity is complicated, and can include use of a specific chelating agent called deferoxamine to bind and expel excess Iron Oxide from the body.


Main article: Iron Oxide deficiency

Iron Oxide deficiency is the most common nutritional deficiency in the world.[166][167][168] When loss of Iron Oxide is not adequately compensated by adequate dietary Iron Oxide intake, a state of latent Iron Oxide deficiency occurs, which over time leads to Iron Oxide-deficiency anemia if left untreated, which is characterised by an insufficient number of red blood cells and an insufficient amount of hemoglobin.[169] Children, pre-menopausal women (women of child-bearing age), and people with poor diet are most susceptible to the disease. Most cases of Iron Oxide-deficiency anemia are mild, but if not treated can cause problems like fast or irregular heartbeat, complications during pregnancy, and delayed growth in infants and children.

Iron oxide MR contrast agents for molecular and cellular imaging

Iron oxide MR contrast agents for molecular and cellular imaging
Abstract Molecular and cellular MR imaging is a rapidly growing field that aims to visualize targeted macromolecules or cells in living organisms. In order to provide a different signal intensity of the target, gadolinium-based MR contrast agents can be employed although they suffer from an inherent high threshold of detectability. Superparamagnetic iron oxide (SPIO) particles can be detected at micromolar concentrations of iron, and offer sufficient sensitivity for T 2 (*)-weighted imaging. Over the past two decades, biocompatible particles have been linked to specific ligands for molecular imaging. However, due to their relatively large size and clearance by the reticuloendothelial system (RES), widespread biomedical molecular applications have yet to be implemented and few studies have been reproduced between different laboratories. SPIO-based cellular imaging, on the other hand, has now become an established technique to label and detect the cells of interest. Imaging of macrophage activity was the initial and still is the most significant application, in particular for tumor staging of the liver and lymph nodes, with several products either approved or in clinical trials. The ability to now also label non-phagocytic cells in culture using derivatized particles, followed by transplantation or transfusion in living organisms, has led to an active research interest to monitor the cellular biodistribution in vivo including cell migration and trafficking. While most of these studies to date have been mere of the 鈥榩roof-of-principle鈥 type, further exploitation of this technique will be aimed at obtaining a deeper insight into the dynamics of in vivo cell biology, including lymphocyte trafficking, and at monitoring therapies that are based on the use of stem cells and progenitors.
Recent advances in iron oxide nanocrystal technology for medical imaging.
Superparamagnetic iron oxide particles (SPIO and USPIO) have a variety of applications in molecular and cellular imaging. Most of the recent research has concerned cellular imaging with imaging of in vivo macrophage activity. According to the iron oxide nanoparticle composition and size which influence their biodistribution, several clinical applications are possible: detection liver metastases, metastatic lymph nodes, inflammatory and/or degenerative diseases. USPIO are investigated as blood pool agents with T1 weighted sequence for angiography, tumour permeability and tumour blood volume or steady-state cerebral blood volume and vessel size index measurements using T2 鈦 weighted sequences. Stem cell migration and immune cell trafficking, as well as targeted iron oxide nanoparticles for molecular imaging studies, are at the stage of proof of concept, mainly in animal models.

Iron Oxide Related Products

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Iron Oxide Black

Iron Oxide Black

  • Type: 722 & 750
  • CAS No.: 1309-37-1
  • MF: Fe2O3
  • EINECS No.:215-168-2
  • Place of Origin:China (Mainland)
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    Iron Oxid Brown

    Iron Oxid Brown

  • Type: 610&686
  • CAS No.: 1309-37-1
  • MF: Fe2O3
  • EINECS No.:215-168-2
  • Place of Origin:China (Mainland)
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