Iron(II,III) oxide
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IUPAC name
iron(II) iron(III) oxide
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Other names
ferrous ferric oxide, ferrosoferric oxide, iron(II,III) oxide, magnetite, black iron oxide, lodestone, rust, iron(II) diiron(III) oxide
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100.013.889 |
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Properties | |
Fe3O4 FeO.Fe2O3 | |
Molar mass | 231.533 g/mol |
Appearance | solid black powder |
Density | 5 g/cm3 |
Melting point | 1,597 °C (2,907 °F; 1,870 K) |
Boiling point | 2,623[1] °C (4,753 °F; 2,896 K) |
Refractive index (nD)
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2.42[2] |
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NFPA 704 (fire diamond) | |
Thermochemistry | |
Std enthalpy of (ΔfH⦵298)formation |
-1120.89 kJ·mol−1[3] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Iron(II,III) oxide, or black iron oxide, is the chemical compound with formula Fe3O4. It occurs in nature as the mineral
Preparation
Heated iron metal interacts with steam to form iron oxide and hydrogen gas.
Under anaerobic conditions, ferrous hydroxide (Fe(OH)2) can be oxidized by water to form magnetite and molecular hydrogen. This process is described by the Schikorr reaction:
This works because crystalline magnetite (Fe3O4) is thermodynamically more stable than amorphous ferrous hydroxide (Fe(OH)2 ).[6]
The Massart method of preparation of magnetite as a ferrofluid, is convenient in the laboratory: mix iron(II) chloride and iron(III) chloride in the presence of sodium hydroxide.[7]
A more efficient method of preparing magnetite without troublesome residues of sodium, is to use ammonia to promote chemical co-precipitation from the iron chlorides: first mix solutions of 0.1 M FeCl3·6H2O and FeCl2·4H2O with vigorous stirring at about 2000 rpm. The molar ratio of the FeCl3:FeCl2 should be about 2:1. Heat the mix to 70 °C, then raise the speed of stirring to about 7500 rpm and quickly add a solution of NH4OH (10 volume %). A dark precipitate of nanoparticles of magnetite forms immediately.[8]
In both methods, the precipitation reaction relies on rapid transformation of acidic iron ions into the spinel iron oxide structure at pH 10 or higher.
Controlling the formation of magnetite nanoparticles presents challenges: the reactions and phase transformations necessary for the creation of the magnetite spinel structure are complex.
Pigment quality Fe3O4, so called synthetic magnetite, can be prepared using processes that use industrial wastes, scrap iron or solutions containing iron salts (e.g. those produced as by-products in industrial processes such as the acid vat treatment (pickling) of steel):
- Oxidation of Fe metal in the Laux process where nitrobenzene is treated with iron metal using FeCl2 as a catalyst to produce aniline:[5]
- C6H5NO2 + 3 Fe + 2 H2O → C6H5NH2 + Fe3O4
- Oxidation of FeII compounds, e.g. the precipitation of iron(II) salts as hydroxides followed by oxidation by aeration where careful control of the pH determines the oxide produced.[5]
Reduction of Fe2O3 with hydrogen:[13][14]
- 3Fe2O3 + H2 → 2Fe3O4 +H2O
Reduction of Fe2O3 with CO:[15]
- 3Fe2O3 + CO → 2Fe3O4 + CO2
Production of nano-particles can be performed chemically by taking for example mixtures of FeII and FeIII salts and mixing them with alkali to precipitate colloidal Fe3O4. The reaction conditions are critical to the process and determine the particle size.[16]
Iron(II) carbonate can also be thermally decomposed into Iron(II,III):[17]
- 3FeCO3 → Fe3O4 + 2CO2 + CO
Reactions
Reduction of magnetite ore by CO in a blast furnace is used to produce iron as part of steel production process:[4]
Controlled oxidation of Fe3O4 is used to produce brown pigment quality γ-Fe2O3 (maghemite):[18]
More vigorous calcining (roasting in air) gives red pigment quality α-Fe2O3 (hematite):[18]
Structure
Fe3O4 has a cubic inverse spinel group structure which consists of a cubic close packed array of oxide ions where all of the Fe2+ ions occupy half of the octahedral sites and the Fe3+ are split evenly across the remaining octahedral sites and the tetrahedral sites.
Both
The ferrimagnetism of Fe3O4 arises because the electron spins of the FeII and FeIII ions in the octahedral sites are coupled and the spins of the FeIII ions in the tetrahedral sites are coupled but anti-parallel to the former. The net effect is that the magnetic contributions of both sets are not balanced and there is a permanent magnetism.[4]
In the molten state, experimentally constrained models show that the iron ions are coordinated to 5 oxygen ions on average.[19] There is a distribution of coordination sites in the liquid state, with the majority of both FeII and FeIII being 5-coordinated to oxygen and minority populations of both 4- and 6-fold coordinated iron.
Properties
Fe3O4 is
While it has much higher
Uses
Clinical data | |
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Trade names | Feraheme, Rienso |
AHFS/Drugs.com | Monograph |
MedlinePlus | a614023 |
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Fe3O4 is used as a black pigment and is known as C.I pigment black 11 (C.I. No.77499) or Mars Black.[18]
Fe3O4 is used as a catalyst in the
Bluing is a passivation process that produces a layer of Fe3O4 on the surface of steel to protect it from rust. Along with sulfur and aluminium, it is an ingredient in steel-cutting thermite.[citation needed]
Medical uses
Nano particles of Fe3O4 are used as contrast agents in MRI scanning.[27]
Ferumoxytol, sold under the brand names Feraheme and Rienso, is an
Biological occurrence
Magnetite has been found as nano-crystals in magnetotactic bacteria (42–45 nm)[5] and in the beak tissue of homing pigeons.[30]
References
- ^ Magnetite (Fe3O4): Properties, Synthesis, and Applications Lee Blaney, Lehigh Review 15, 33-81 (2007). See Appendix A, p.77
- ISBN 0-07-049439-8
- ^ Chase MW (1998). "NIST-JANAF Themochemical Tables". NIST (Fourth ed.): 1–1951.
- ^ ISBN 978-0-08-037941-8.
- ^ ISBN 978-3-527-60644-3.
- PMID 23294626.
- .
- S2CID 35129018.
- PMID 14973569.
- .
- .
- S2CID 34153665.
- ^ US 2596954, Heath TD, "Process for reduction of iron ore to magnetite", issued 13 May 1952, assigned to Dorr Company
- .
- S2CID 94274056.
- ISBN 0-8247-0796-6
- ^ "FeCO3 = Fe3O4 + CO2 + CO | The thermal decomposition of iron(II) carbonate". chemiday.com. Retrieved 2022-10-14.
- ^ ISBN 3-527-30363-4
- S2CID 226248368.
- S2CID 41925681.
- S2CID 250773238.
- .
- ^ a b c "Feraheme- ferumoxytol injection". DailyMed. 9 July 2020. Retrieved 14 September 2020.
- ^ a b "Rienso EPAR". European Medicines Agency. 17 September 2018. Retrieved 14 September 2020.
- ^ "Ferumoxytol (Feraheme) Use During Pregnancy". Drugs.com. 15 May 2020. Retrieved 14 September 2020.
- ^ ISBN 0-8247-5563-4
- PMID 10092379.
- S2CID 7748714.
- ^ a b "Drug Approval Package: Feraheme (Ferumoxytol) Injection NDA #022180". U.S. Food and Drug Administration (FDA). Retrieved 14 September 2020.
Rieves D (June 23, 2009). "Application Number: 22-180" (PDF) (Summary Review). Center for Drug Evaluation and Research. - S2CID 39216462.
External links
- "Ferumoxytol". Drug Information Portal. U.S. National Library of Medicine.