IRON OXIDE

IRON OXIDE

CAS NO.: 1332-37-2
EC/LIST NO.: 215-570-8

Iron oxides are chemical compounds composed of iron and oxygen. 
There are sixteen known iron oxides and oxyhydroxides, the best known of which is rust, a form of iron(III) oxide. 

Iron oxides and oxyhydroxides are widespread in nature and play an important role in many geological and biological processes. 
They are used as iron ores, pigments, catalysts, and in thermite, and occur in hemoglobin. 
Iron oxides are inexpensive and durable pigments in paints, coatings and colored concretes. 
Colors commonly available are in the "earthy" end of the yellow/orange/red/brown/black range. 
When used as a food coloring, it has E number E172.

Iron oxide materials yield pigments that are nontoxic, nonbleeding, weather resistant, and lightfast.   
Natural iron oxides include a combination of one or more ferrous or ferric oxides, and impurities, such as manganese, clay, or organics.   
Synthetic iron oxides can be produced in various ways, including thermal decomposition of iron salts, such as ferrous sulfate, to produce reds; precipitation to produce yellows, reds, browns, and blacks (e.g., the Penniman-Zoph process); and reduction of organic compounds by iron (e.g., nitrobenzene reduced to aniline in the presence of particular chemicals) to produce yellows and blacks.   
Reds can be produced by calcining either yellow or blacks.

 
A group of minerals and inorganic compounds made up of iron that is in +2 (ferrous) and +3 (ferric) valence states and oxygen in the –2 valence state, such as ferrous oxide, FeO, and ferric oxide, Fe2O3. 
Fe3O4 is a mixture of ferric oxide and ferrous oxide that commonly occurs in a fine-grained, magnetic crystalline form. 
Hematite, Fe2O3, the most common iron oxide, exists in several crystalline forms. 
Other forms of hematite are too abrasive to use as weighting material in drilling fluids.

Iron-oxide nodules or concretions are the most common kind of meteorwrong sent to us. 
Hematite and magnetite are two common iron-oxide minerals. 
Most iron ore deposits consist mainly of hematite, magnetite, or both. 
Iron-oxide concretions, iron-oxide nodules, and ironstones are often mistaken for meteorites because they are heavy (dense) and their unusual (frequently bizarre!) shapes catch people’s attention.

Iron Oxide is a mineral which varies in colour, from black or silver-grey to brown, reddish-brown or red. We mine our iron oxide as the main ore of Iron.

Iron oxide nanoparticles demonstrate a number of unique properties, including superparamagnetism, biocompatibility, and non-toxicity, which make them an ideal candidate for a variety of applications, as described in this book. 
Chapter One deals with the recent advances in various synthetic procedures of iron oxide-based nanocomposites, their characterization methods, and their potential applications in energy storage devices, supercapacitors, fuel cells, and more. 
Chapter Two summarizes current applications of immobilized enzymes based on iron oxide magnetic nanoparticles and discusses future growth prospects. 
Chapter Three reviews the properties and applications of enzymatic sensors in exploiting tyrosinase, glucose oxidase, and other enzymes for sensing a broad range of biomedical species. 
Chapter Four discusses magnetic magnetite and maghemite iron oxide nanoparticles from a variety of perspectives.
Chapter Five describes how nano iron oxides could be used to remove pollutants from the environment. 
Chapter Six provides a comprehensive review of the catalytic applications of iron oxide nanoparticles in organic synthesis, high temperature reactions, gas-phase processes, wastewater treatment and supercritical upgradation of heavy petroleum oils. 
Chapter Seven details the photocatalytic degradation of a class of toxic, aromatic pollutants, namely, phenols and substituted phenols using different types of photocatalysts in the nano size range for effective removal these compounds from water bodies. 
Lastly, Chapter Eight elucidates various magnetic nanomaterials-based adsorbents used in adsorption techniques for wastewater treatment.

Iron oxide, which is also called ferric oxide, is an inorganic compound having the chemical formula Fe2O3. 
Iron oxides is one of the 3 major oxides of iron, and the remaining two being iron(II) oxide (FeO), which is the rare iron (II, and III) oxide (Fe3O4), and also naturally takes place as the mineral magnetite. 
Since the mineral is referred to as hematite, Fe2O3 is iron’s primary source for the steel industry and is readily attacked by acids. 
Often, iron oxide can be referred to as rust. 
This label is useful to some extent because rust shares many properties and has the same composition. 
But, in chemistry, rust is considered an ill-defined material, which can be described as Hydrous ferric oxide.

 
Iron oxide is a compound made from iron and oxygen. 
There are 16 known iron oxides and oxyhydroxides, the most famous of which is rust, a type of ferric oxide.  
Iron oxides and oxyhydroxides are widespread and play  important roles in many geological and biological processes. 
They are used in iron ore, pigments, catalysts, thermites and are contained in hemoglobin. 
Iron oxide is a cheap and permanent pigment found in paints, coatings, and colored concrete. 
Commonly available colors are on the "soil" edge of the yellow / orange / red / brown / black range. 
When used as a food coloring, the E number is E172.

Iron is an element that, in its bulk form, is used in such everyday settings as stair railings and the structural beams in cars or buildings. 
Iron is also present in water and in our bloodstream, where it helps to transport oxygen. 
Iron is one of the materials that we can use to make magnets due to the way electrons orbit each atom. 
And, as we all know, iron rusts when you combine iron and oxygen to form iron oxide. 
Iron oxides turns out that nanoparticles of both iron and iron oxide can be quite useful.

If iron is left in the rain it will rust, and rust is composed of iron oxide, a molecule that contains three atoms of iron and four atoms of oxygen. 
Like iron, iron oxide has magnetic properties. 
Iron has four unpaired electrons, whereas iron oxide has only two unpaired electrons. 
Because the unpaired electrons make a material magnetic, iron oxide is less magnetic than iron. 
Iron oxide is therefore called a paramagnetic material. 
The paramagnetic properties of iron oxide nanoparticles are not changed from the bulk material except that these tiny particles can go where larger particles never could.

The Iron Oxide (IO) ratio method is a geological index for identifying rock features that have experienced oxidation of iron-bearing sulfides using the red and blue bands. 
Iron oxides is useful in identifying iron oxide features below vegetation canopies and is used in mineral composite mapping.

The ordinary black iron oxide has been used in both copperplate and die stamping inks.
Iron oxides of iron constitute the main component of products in the pharmaceutical industry, paint industry, plastic industry, ink industry and cosmetic industry.
Used as a pigment of natural origin inclusive titanium dioxide.
Iron oxides salt are used as a flocculant in wastewater treatment the dyeing of textiles and the production of fertilizer and feed additives.
Used as a polishing material in the jewellery trade.

Magnetic iron oxide nanoparticles have attracted attention because of their idiosyncratic physicochemical characteristics and vast range of applications such as protein separations, catalysis, magnetic resonance imaging (MRI), magnetic sensors, drug delivery, and magnetic refrigeration. 
The activity of the catalyst depends on the chemical composition, particle size, morphology and also on the atomic arrangements at the surface. 
The catalytic properties of iron oxide nanoparticles can be easily altered by controlling the shape, size, morphology and surface modification of nanomaterials. 
This review is focused on the use of iron oxide as a catalyst in various organic reactions viz. oxidation, hydrogenation, C-C coupling, dihydroxylation reactions and its reusability/recoverability

Some iron oxides are widely used in ceramic applications, particularly in glazing. 
Many metal oxides provide the colors in glazes after being fired at high temperatures.

Iron oxides yield pigments (see Iron oxide pigments).
Natural iron oxides pigments are called ochers. 
Many classic paint colors, such as raw and burnt siennas and umbers, are iron-oxide pigments. 
These pigments have been used in art since the earliest prehistoric art known, the cave paintings at Lascaux and nearby sites. 
Iron (III) oxide is typically used.

Iron pigments are also widely used in the cosmetic field. 
They are considered to be nontoxic, moisture resistant, and nonbleeding. 
Iron oxides graded safe for cosmetic use are produced synthetically in order to avoid the inclusion of ferrous or ferric oxides, and impurities normally found in naturally occurring iron oxides. 
Typically, the Iron(II) oxide pigment is black, while the Iron(III) oxide is red or rust-colored. 
(Iron compounds other than oxides can be other colors.)

Under conditions favoring iron reduction, the process of iron oxide reduction can replace at least 80% of methane production occurring by methanogenesis.
This phenomenon occurs in a nitrogen-containing (N2) environment with low sulfate concentrations. 
Methanogenesis, an Archaean driven process, is typically the predominant form of carbon mineralization in sediments at the bottom of the ocean. 
Methanogenesis completes the decomposition of organic matter to methane (CH4).
The specific electron donor for iron oxide reduction in this situation is still under debate, but the two potential candidates include either titanium (III) or compounds present in yeast. 
The predicted reactions with titanium (III) serving as the electron donor and phenazine-1-carboxylate (PCA) serving as an electron shuttle is as follows:

Ti(III)-cit + CO2 + 8H+ → CH4 + 2H2O + Ti(IV) + cit                           
ΔE = –240 + 300 mV
Ti(III)-cit + PCA (oxidized) → PCA (reduced) + Ti(IV) + cit                
ΔE = –116 + 300 mV
PCA (reduced) + Fe(OH)3 → Fe2+ + PCA (oxidized)                         
ΔE = –50 + 116 mV  
Note: cit = citrate.

Titanium (III) is oxidized to titanium (IV) while PCA is reduced. 
The reduced form of PCA can then reduce the iron hydroxide (Fe(OH)3).

On the other hand when airborne, iron oxides have been shown to harm the lung tissues of living organisms by the formation of hydroxyl radicals, leading to the creation of alkyl radicals. 
The following reactions occur when Fe2O3 and FeO, hereafter represented as Fe3+ and Fe2+ respectively, iron oxide particulates accumulate in the lungs. 

O2 + e− → O2• −[13]

The formation of the superoxide anion (O2• −) is catalyzed by a transmembrane enzyme called NADPH oxidase. 
The enzyme facilitates the transport of an electron across the plasma membrane from cytosolic NADPH to extracellular oxygen (O2) to produce O2• −. 
NADPH and FAD are bound to cytoplasmic binding sites on the enzyme. 
Two electrons from NADPH are transported to FAD which reduces it to FADH2. 
Then, one electron moves to one of two heme groups in the enzyme within the plane of the membrane. 
The second electron pushes the first electron to the second heme group so that it can associate with the first heme group.
 For the transfer to occur, the second heme must be bound to extracellular oxygen which is the acceptor of the electron. 
This enzyme can also be located within the membranes of intracellular organelles allowing the formation of O2• − to occur within organelles. 

2O2• − + 2 H+ → H2O2 + O2 [13][15]

The formation of hydrogen peroxide (H2O2) can occur spontaneously when the environment has a lower pH especially at pH 7.4.
The enzyme superoxide dismutase can also catalyze this reaction. 
Once H2O2 has been synthesized, it can diffuse through membranes to travel within and outside the cell due to its nonpolar nature.

Fe2+ + H2O2 → Fe3+ + HO• +  OH−Fe3+ + H2O2 → Fe2+ + O2• − + 2H+H2O2 + O2• − → HO• + OH− + O2  

Fe2+ is oxidized to Fe3+ when it donates an electron to H2O2, thus, reducing H2O2 and forming a hydroxyl radical (HO•) in the process. 
H2O2 can then reduce Fe3+ to Fe2+ by donating an electron to it to create O2• −. 
O2• − can then be used to make more H2O2 by the process previously shown perpetuating the cycle, or it can react with H2O2 to form more hydroxyl radicals. 
Hydroxyl radicals have been shown to increase cellular oxidative stress and attack cell membranes as well as the cell genomes. 

HO• + RH → R• + H2O  

The HO• radical produced from the above reactions with iron can abstract a hydrogen atom (H) from molecules containing an R-H bond where the R is a group attached to the rest of the molecule, in this case H, at a carbon (C). 

IUPAC NAME:

Amorphous aluminum silicate
 
diiron trioxide
 
iron (II) oxide
 
iron (III) oxide
 
iron (iii) oxide
 
IRON OXIDE

SYNONYMS:

Eisenhydrat (1:1) [German] [ACD/IUPAC Name]
Fer, hydrate (1:1) [French] [ACD/IUPAC Name]
ferrous oxide
Iron hydrate (1:1) [ACD/IUPAC Name]
12315-09-2 [RN]
1332-37-2 [RN]
1345-25-1 [RN]
15092-05-4 [RN]
Eisenhydrat