Iron ( or ; ) is a chemical element with the symbol Fe () and atomic number 26. It is a metal in the first transition series. It is the most common element in the whole planet Earth, forming much of Earth's outer and inner core, and it is the fourth most common element in the Earth's crust. It is produced in abundance as a result of fusion in high-mass stars, where the production of nickel-56 (which decays to iron) is the last nuclear fusion reaction that is exothermic, becoming the last element to be produced before collapse of a supernova leads to events that scatter the precursor radionuclides of iron into space.
Like other Group 8 elements, iron exists in a wide range of oxidation states, −2 to + 6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen and water. Fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give iron oxides, also known as rust. Unlike many other metals which form passivating oxide layers, iron oxides occupy more volume than iron metal, and thus iron oxides flake off and expose fresh surfaces for corrosion.
Iron metal has been used since ancient times, though lower-melting copper alloys were used first in history. Pure iron is soft (softer than aluminium), but is unobtainable by smelting. The material is significantly hardenened and strengthened by impurities from the smelting process, such as carbon. A certain proportion of carbon (between 0.2% and 2.1%) produces steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to cast iron. Further refinement with oxygen reduces the carbon content to make steel. Steels and low carbon iron alloys with other metals (alloy steels) are by far the most common metals in industrial use, due to their great range of desirable properties.
Iron chemical compounds, which include ferrous and ferric compounds, have many uses. Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. It forms binary compounds with the halogens and the chalcogens. Among its organometallic compounds, ferrocene was the first sandwich compound discovered.
Iron 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 is also the metal used at the active site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants and animals.
Characteristics
Mechanical properties
{|class="wikitable" style="float:left; text-size: 80%"
|+ Characteristic values of
tensile strength (TS) and
Brinell hardness (BH) of different forms of iron.
!Material
!TS (MPa)
!BH (
Brinell)
|-
|
Iron whiskers
|11000
|
|-
|Ausformed (hardened) steel
|2930
|850–1200
|-
|
Martensitic steel
|2070
|600
|-
|
Bainitic steel
|1380
|400
|-
|
Pearlitic steel
|1200
|350
|-
|Cold-worked iron
|690
|200
|-
|Small-grain iron
|340
|100
|-
|Carbon-containing iron
|140
|40
|-
|Pure, single-crystal iron
|10
|3
|}
Mechanical properties of iron and its alloys are evaluated using a variety of tests, such as the Brinell test, Rockwell test, or tensile strength tests, among others; the results on iron are so consistent that iron is often used to calibrate measurements or to relate the results of one test to another. Those measurements reveal that mechanical properties of iron crucially depend on purity: Purest research-purpose single crystals of iron are softer than aluminium. Addition of only 10 parts per million of carbon doubles their strength. The purest industrially produced iron (about 99.99% purity) has a hardness of 20–30 Brinell.
Phase diagram and allotropes
Iron represents an example of
allotropy in a metal. There are at least four allotropic forms of iron, known as α, γ, δ, and ε; at very high pressures, some controversial experimental evidence exists for a phase β stable at very high pressures and temperatures.
of pure iron]]
As molten iron cools down it crystallizes at 1538 °C into its δ allotrope, which has a
body-centered cubic (bcc) crystal structure. As it cools further its
crystal structure changes to
face-centered cubic (fcc) at 1394 °C, when it is known as γ-iron, or
austenite. At 912 °C the crystal structure again becomes bcc as α-iron, or
ferrite, is formed, and at 770 °C (the
Curie point, T
c) iron becomes
magnetic. As the iron 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 atoms with a particular electronic spin. In unmagnetized iron, all the electronic spins of the atoms within one domain are in the same direction; the neighboring domains point in various directions and thus cancel out. In magnetized iron, the electronic spins of all the domains are aligned, so that the magnetic effects of neighboring domains reinforce each other. Although each domain contains billions of atoms, they are very small, about 10 micrometres across.. At pressures above approximately 10 GPa and temperatures of a few hundred kelvin or less, α-iron changes into a
hexagonal close-packed (hcp) structure, which is also known as
ε-iron; the higher-temperature γ-phase also changes into ε-iron, 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; it has been thought to have an orthorhombic or a double hcp structure.
Above 912 °C and up to 1400 °C α-iron undergoes a phase transition from bcc to the fcc configuration of γ-iron, also called austenite. This 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 is used in the type of stainless steel used for making cutlery, and hospital and food-service equipment.
Isotopes
Naturally occurring iron consists of four stable isotopes: 5.845% of 54Fe, 91.754% of 56Fe, 2.119% of 57Fe and 0.282% of 58Fe. The nuclide 54Fe is predicted to undergo double beta decay, but this process had never been observed experimentally for these nuclei, and only the lower limit on the half-life was established: t1/2>3.1×1022 years. 60Fe is an extinct radionuclide of long half-life (2.6 million years).
Much of the past work on measuring the isotopic composition of Fe has focused on determining 60Fe variations due to processes accompanying nucleosynthesis (i.e., meteorite studies) and ore formation. In the last decade however, advances in mass spectrometry technology have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of iron. Much of this work has been driven by the Earth and planetary science communities, although applications to biological and industrial systems are beginning to emerge.
The most abundant iron isotope 56Fe is of particular interest to nuclear scientists as it represents the most common endpoint of nucleosynthesis. It is often cited, falsely, as the isotope of highest binding energy, a distinction which actually belongs to Nickel-62. Since 56Ni is easily produced from lighter nuclei in the alpha process in nuclear reactions in supernovae (see silicon burning process), nickel-56 (14 alpha particles) is the endpoint of fusion chains inside extremely massive stars, since addition of another alpha particle would result in zinc-60, which requires a great deal more energy. This nickel-56, which has a half-life of about 6 days, is therefore made in quantity in these stars, but soon decays by two successive positron emissions within supernova decay products in the supernova remnant gas cloud, to first radioactive cobalt-56, and then stable iron-56. This last nuclide is therefore common in the universe, relative to other stable metals of approximately the same atomic weight.
In phases of the meteorites Semarkona and Chervony Kut a correlation between the concentration of 60Ni, the daughter product of 60Fe, and the abundance of the stable iron isotopes could be found which is evidence for the existence of 60Fe at the time of formation of the solar system. Possibly the energy released by the decay of 60Fe contributed, together with the energy released by decay of the radionuclide 26Al, to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of 60Ni present in material may also provide further insight into the origin of the solar system and its early history.
Of the stable isotopes, only 57Fe has a nuclear spin (−1/2).
Nuclei of iron atoms have some of the highest binding energies per nucleon, surpassed only by the nickel isotope 62Ni. This is formed by nuclear fusion in stars. Although a further tiny energy gain could be extracted by synthesizing 62Ni, conditions in stars are unsuitable for this process to be favored. Elemental distribution on Earth greatly favors iron over nickel, and also presumably in supernova element production.
Iron-56 is the heaviest stable isotope produced by the alpha process in stellar nucleosynthesis; elements heavier than iron and nickel require a supernova for their formation. Iron is the most abundant element in the core of red giants, and is the most abundant metal in iron meteorites and in the dense metal cores of planets such as Earth.
Nucleosynthesis
Iron is created by extremely large, extremely hot (over 2.5 billion kelvin) stars, through a process called the
silicon burning process. It is the heaviest stable element to be produced in this manner. The process starts with the second largest stable nucleus created by silicon burning: calcium. One stable nucleus of calcium fuses with one helium nucleus, creating unstable titanium. Before the titanium decays, it can fuse with another helium nucleus, creating unstable chromium. Before the chromium decays, it can fuse with another helium nucleus, creating unstable iron. Before the iron decays, it can fuse with another helium nucleus, creating unstable nickel-56. Any further fusion of nickel-56 consumes energy instead of producing energy, so after the production of nickel-56, the star does not produce the energy necessary to keep the core from collapsing. Eventually, the nickel-56 decays to unstable cobalt-56 which, in turn decays to stable
iron-56
When the core of the star collapses, it creates a
Supernova. Supernovas also create additional forms of stable iron via the
r-process.
Occurrence
Planetary occurrence
s of similar composition of Earth's inner and outer core]]
Iron is the sixth most
abundant element in the
Universe, formed as the final step of
nucleosynthesis, by
silicon fusing in massive stars. Metallic iron 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-
nickel alloy constituting 35% of the mass of the Earth as a whole. Iron is consequently the most abundant element on Earth, but only the fourth most abundant element in the Earth's crust. Most of the iron in the crust is found combined with oxygen as
iron oxide minerals such as
hematite and
magnetite. Large deposits of iron are found in
banded iron formations. These geological formations are a type of rock consisting of repeated thin layers of
iron oxides, either
magnetite (Fe
3O
4) or
hematite (Fe
2O
3), alternating with bands of iron-poor
shale and
chert. The banded iron formations are common in the time between and
About 1 in 20 meteorites consist of the unique iron-nickel minerals taenite (35–80% iron) and kamacite (90–95% iron). Although rare, iron meteorites are the main form of natural metallic iron on the Earth's surface. It was proven by Mössbauer spectroscopy that the red color of the surface of Mars is derived from an iron oxide-rich regolith.
Chemistry and compounds
Iron forms compounds mainly in the +2 and +3 oxidation states. Traditionally, iron(II) compounds are called ferrous, and iron(III) compounds ferric. Iron also occurs in higher oxidation states, an example being the purple potassium ferrate (K2FeO4) which contains iron in its +6 oxidation state. Iron(IV) is a common intermediate in many in 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(II) and iron(III) centers, such as magnetite and Prussian blue (Fe4(Fe[CN]6)3).
, also known as ferric chloride]]
The iron compounds produced on the largest scale in industry are iron(II) sulfate (FeSO4·7H2O) and iron(III) chloride (FeCl3). The former is one of the most readily available sources of iron(II), but is less stable to aerial oxidation than Mohr's salt ((NH4)2Fe(SO4)2·6H2O). Iron(II) compounds tend to be oxidized to iron(III) compounds in the air.
Binary compounds
Iron reacts with oxygen in the air to form various
oxide and hydroxide compounds; the most common are
iron(II,III) oxide (Fe
3O
4), and
iron(III) oxide (Fe
2O
3).
Iron(II) oxide also exists, though it is unstable at room temperature. These oxides are the principal ores for the production of iron (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 pyrite (FeS
2), also known as fool's gold owing to its golden luster. Prussian blue can be used in laundry bluing to correct the yellowish tint left by ferrous salts in water.
Several carbonyl compounds of iron are known. The premier iron(0) compound is iron pentacarbonyl, Fe(CO)5, which is used to produce carbonyl iron powder, a highly reactive form of metallic iron. Thermolysis of iron pentacarbonyl gives the trinuclear cluster, triiron dodecacarbonyl. Collman's reagent, disodium tetracarbonylferrate, is a useful reagent for organic chemistry; it contains iron in the −2 oxidation state. Cyclopentadienyliron dicarbonyl dimer contains iron in the rare +1 oxidation state.
Ferrocene is an extremely stable complex. The first sandwich compound, it contains an iron(II) center with two cyclopentadienyl ligands bonded through all ten carbon atoms. This arrangement was a shocking novelty when it was first discovered, but the discovery of ferrocene has led to a new branch of organometallic chemistry. Ferrocene itself can be used as the backbone of a ligand, e.g. dppf. Ferrocene can itself be oxidized to the ferrocenium cation (Fc+); the ferrocene/ferrocenium couple is often used as a reference in electrochemistry.
History
Wrought iron
is an example of the iron extraction and processing methodologies of India. The iron pillar at Delhi has withstood corrosion for the last 1600 years.]]
Iron objects of great age are much rarer than objects made of gold or silver due to the ease of corrosion of iron. Beads made of
meteoric iron in 3500 B.C. 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 found in the Earth's crust has very little to no nickel content. Meteoric iron was highly regarded due to its origin in the heavens and was often used to forge weapons and tools or whole specimens placed in churches. Items that were likely made of iron by Egyptians date from 2500 to 3000 BC. Iron had a distinct advantage over bronze in warfare implements. It was much harder and more durable than bronze, although susceptible to rust. However, this is contested.
Hittitologist Trevor Bryce argues that before advanced iron-working techniques were developed in
Europe and
India,
cast-iron weapons used by early
Mesopotamian armies had a tendency to shatter in combat, due to their high carbon content.
The first iron production started in the Middle Bronze Age but it took several centuries before iron displaced bronze. Samples of smelted iron from Asmar, Mesopotamia and Tall Chagar Bazaar in northern Syria were made sometime between 2700 and 3000 BC. The Hittites appear to be the first to understand the production of iron from its ores and regard it highly in their society. and in the Levant from about 1500 BC (suggesting smelting in Anatolia or the Caucasus).
The Book of Genesis, fourth chapter, verse 22 contains the first mention of iron in the Old Testament of the Bible; "Tubal-cain, an instructor of every artificer in brass and iron." Other verses allude to iron mining (Job 28:2), iron used as a stylus (Job 19:24), furnace (Deuteronomy 4:20), chariots (Joshua 17:16), nails (I Chron. 22:3), saws and axes (II Sam. 12:31), and cooking utensils (Ezekiel 4:3). The metal is also mentioned in the New Testament, for example in Acts chapter 12 verse 10, "[Peter passed through] the iron gate that leadeth unto the city" of Antioch. The Quran referred to Iron 1400 years ago.
Iron working was introduced to Greece in the late 11th century BC. The spread of ironworking in Central and Western Europe is associated with Celtic expansion. According to Pliny the Elder, iron use was common in the Roman era. The annual iron output of the Roman Empire is estimated at 84,750 t, while the similarly populous Han China produced around 5,000 t.
During the Industrial Revolution in Britain, Henry Cort began refining iron from pig iron to wrought iron (or bar iron) using innovative production systems. In 1783 he patented the puddling process for refining iron ore. It was later improved by others including Joseph Hall.
Cast iron
Cast iron was first produced in
China about 550 BC, but was hardly in Europe until the medieval period. During the
medieval period, means were found in Europe of producing wrought iron from cast iron (in this context known as
pig iron) using
finery forges. For all these processes,
charcoal was required as fuel.
, 1801. Blast furnaces light the iron making town of
Coalbrookdale.]]
Medieval
blast furnaces were about tall and made of fireproof brick; forced air was usually provided by hand-operated bellows.
New methods of producing it by carburizing bars of iron in the cementation process were devised in the 17th century AD. In the Industrial Revolution, new methods of producing bar iron 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, to produce mild steel. This made steel much more economical, thereby leading to wrought iron no longer being produced.
Foundations of modern chemistry
Antoine Lavoisier used the reaction of water steam with metallic iron inside an incandescent iron tube to produce
hydrogen in his experiments leading to the demonstration of the mass conservation. Anaerobic oxidation of iron at high temperature can be schematically represented by the following reactions:
: Fe + H2O → FeO + H2
:2 Fe + 3 H2O → Fe2O3 + 3 H2
:3 Fe + 4 H2O → Fe3O4 + 4 H2
Recent discoveries
discovery of Mossbauer effect is best for iron
many enzymes use iron in the catalytic center
iron-56 is the end product of nuclear fusion; the most stable atomic nucleus of all elements
superconductivity?
magnetic effect
ferrocene
Industrial production
The production of iron or steel is a process containing two main stages, unless the desired product is cast iron. The first stage is to produce pig iron in a blast furnace. Alternatively, it may be directly reduced. The second is to make wrought iron or steel from pig iron by a further process.
to make wrought iron from pig iron, with the right illustration displaying men working a blast furnace, from the
Tiangong Kaiwu encyclopedia, published in 1637 by
Song Yingxing.]]
For a few limited purposes like electromagnet cores, pure iron is produced by electrolysis of a ferrous sulfate solution and contains varying amounts of contaminants such as sulfur, silicon and phosphorus. Pig iron is not a saleable product, but rather an intermediate step in the production of cast iron and steel from iron ore. Cast iron contains 2–4% carbon, 1–6% silicon, and small amounts of manganese. Contaminants present in pig iron that negatively affect material properties, such as sulfur and phosphorus, have been reduced to an acceptable level. It 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 are heated together. Its mechanical properties vary greatly, dependent upon the form carbon takes in the alloy.
"White" cast irons contain their carbon in the form of cementite, or iron carbide. This hard, brittle compound dominates the mechanical properties of white cast irons, rendering them hard, but unresistant to shock. The broken surface of a white cast iron is full of fine facets of the broken carbide, a very pale, silvery, shiny material, hence the appellation.
In gray iron the carbon exists free as fine flakes of graphite, and also renders the material brittle due to the stress-raising nature of the sharp edged flakes of graphite. A newer variant of gray iron, referred to as ductile iron is specially treated with trace amounts of magnesium to alter the shape of graphite to spheroids, or nodules, vastly increasing the toughness and strength of the material.
Wrought iron contains less than 0.25% carbon. 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.
Apart from traditional applications, iron 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 and steel is that pure iron, and most of its alloys, suffer badly from rust if not protected in some way. Painting, galvanization, passivation, plastic coating and bluing are all used to protect iron from rust by excluding water and oxygen or by cathodic protection.
Of compounds
Although its metallurgical role is dominant in terms of amounts, iron compounds are pervasive in industry as well being used in many niche uses. Iron 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 in an acidic solvent was used in the
Bechamp reduction the reduction of
nitrobenzene to
aniline.
Iron(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. In animals, plants, and fungi, iron is often the metal ion incorporated into the heme complex. Heme is an essential component of cytochrome proteins, which mediate redox reactions, and of oxygen carrier proteins such as hemoglobin, myoglobin, and leghemoglobin. Inorganic iron also contributes to redox reactions in the iron-sulfur clusters of many enzymes, such as nitrogenase (involved in the synthesis of ammonia from nitrogen and hydrogen) and hydrogenase. Non-heme iron proteins include the enzymes methane monooxygenase (oxidizes methane to methanol), ribonucleotide reductase (reduces ribose to deoxyribose; DNA biosynthesis), hemerythrins (oxygen transport and fixation in Marine invertebrates) and purple acid phosphatase (hydrolysis of phosphate esters).
Iron distribution is heavily regulated in mammals, partly because iron ions have a high potential for biological toxicity.
Iron acquisition poses a problem for aerobic organisms because ferric iron is poorly soluble near neutral pH. Thus, bacteria have evolved high-affinity ing agents called siderophores.
Biological role
Iron is abundant in biology. Iron-proteins are found in all living organisms, ranging from the evolutionarily primitive
archaea to humans. The color of blood is due to the hemoglobin, an iron-containing protein. As illustrated by hemoglobin, iron often is bound to
cofactors, e.g. in
hemes. The
iron-sulfur clusters are pervasive and include
nitrogenase, the enzymes responsible for biological
nitrogen fixation.(see
#Biological role). Influential theories of evolution have invoked a role for iron sulfides,
iron-sulfur world theory.
, in the protein additional
ligand(s) would be attached to Fe.]]
Iron is a necessary
trace element found in nearly all living organisms. Iron-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), and
catalase.
Bioinorganic compounds
The most famous bioinorganic compounds of iron are
heme proteins:
hemoglobin,
myoglobin, and
cytochrome P450. These compounds can transport gases, build
enzymes ,and be used in transferring
electrons.
Metalloproteins are a group of proteins with metal ion
cofactors. Some examples of iron metalloproteins are
ferritin and
rubredoxin. Many enzymes vital to life contain iron, such as
catalase,
lipoxygenases,and
IRE-BP.
Health and diet
Iron is pervasive, but particularly rich sources of dietary iron include
red meat,
lentils,
beans,
poultry,
fish,
leaf vegetables,
tofu,
chickpeas,
black-eyed peas,
blackstrap molasses, fortified bread, and fortified
breakfast cereals. Iron in low amounts is found in
molasses,
teff and
farina. Iron in meat (
heme iron) is more easily absorbed than iron in vegetables. Although most studies suggest that heme/hemoglobin from red meat has effects which may increase the likelihood of
colorectal cancer, there is still some controversy, and even a few studies suggesting that there is not enough evidence to support such claims.
Iron provided by dietary supplements is often found as iron(II) fumarate, although iron sulfate is cheaper and is absorbed equally well. Elemental iron, or reduced iron, despite being absorbed at only one third to two thirds the efficiency (relative to iron sulfate), is often added to foods such as breakfast cereals or enriched wheat flour. Iron is most available to the body when chelated to amino acids and is also available for use as a common iron supplement. Often the amino acid chosen for this purpose is the cheapest and most common amino acid, glycine, leading to "iron glycinate" supplements. The Recommended Dietary Allowance (RDA) for iron varies considerably based on age, gender, and source of dietary iron (heme-based iron has higher bioavailability). Infants may require iron supplements if they are bottle-fed cow's milk. Blood donors and pregnant women are at special risk of low iron levels and are often advised to supplement their iron intake.
Regulation of uptake
Iron uptake is tightly regulated by the human body, which has no regulated physiological means of excreting iron. Only small amounts of iron are lost daily due to mucosal and skin epithelial cell sloughing, so control of iron levels is mostly by regulating uptake.
Regulation of iron uptake is impaired in some people as a result of a genetic defect that maps to the HLA-H gene region on chromosome 6. In these people, excessive iron intake can result in iron overload disorders, such as hemochromatosis. Many people have a genetic susceptibility to iron overload without realizing it or being aware of a family history of the problem. For this reason, it is advised that people do not take iron supplements unless they suffer from iron deficiency and have consulted a doctor. Hemochromatosis is estimated to cause disease in between 0.3 and 0.8% of Caucasians.
MRI finds that iron accumulates in the hippocampus of the brains of those with Alzheimer's disease and in the substantia nigra of those with Parkinson disease.
Permeable reactive barriers
Zero-valent iron is the main reactive material for
permeable reactive barriers.
Precautions
Large amounts of ingested iron can cause excessive levels of iron in the blood. High blood levels of free ferrous iron react with peroxides to produce free radicals, which are highly reactive and can damage DNA, proteins, lipids, and other cellular components. Thus, iron toxicity occurs when there is free iron in the cell, which generally occurs when iron levels exceed the capacity of transferrin to bind the iron. Damage to the cells of the gastrointestinal tract can also prevent them from regulating iron absorption leading to further increases in blood levels. Iron typically damages cells in the heart, liver and elsewhere, which can cause significant adverse effects, including coma, metabolic acidosis, shock, liver failure, coagulopathy, adult respiratory distress syndrome, long-term organ damage, and even death. Overconsumption of iron, 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.
See also
El Mutún in Bolivia, where 20% of the world's accessible iron is located.
Iron fertilization – proposed fertilization of oceans to stimulate phytoplankton growth.
Iron (metaphor)
Iron in folklore
List of countries by iron production
Pelletising – process of creation of iron ore pellets.
Rustproof iron
References
Books
H. R. Schubert, History of the British Iron and Steel Industry ... to 1775 AD (Routledge, London, 1957)
R. F. Tylecote, History of Metallurgy (Institute of Materials, London 1992).
R. F. Tylecote, 'Iron in the Industrial Revolution' in J. Day and R. F. Tylecote, The Industrial Revolution in Metals (Institute of Materials 1991), 200–60.
External links
WebElements.com – Iron
It's Elemental – Iron
The Most Tightly Bound Nuclei
Crystal structure of iron
Chemistry in its element podcast (MP3) from the Royal Society of Chemistry's Chemistry World: Iron
The periodic table of videos: Iron
Category:Biology and pharmacology of chemical elements
Category:Dietary minerals
Iron
Category:Transition metals
Category:Ferromagnetic materials
Category:Building materials
Category:Pyrotechnic fuels
Category:Cubic minerals
