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Iron oxide brown are produced synthetically and consist essentially of anhydrous and/or hydrated iron oxides.
The range of hues includesyellows, reds, browns and blacks.
Food quality iron oxide brown are primarily distinguished from technical grades by the comparatively low levels of contamination by other metals.
CAS: 1309-37-1
MF: Fe2O3
MW: 159.69
EINECS: 215-168-2
Iron oxide brown is achieved by the selection and control of the source of iron and/or by the extent of chemical purification during the manufacturing process.
Iron oxide brown have been used to color confectionery, fillings and decorations for pastry products, cheese products, fish paste, pet foods, cosmetics and pharmaceutical products.
A high-grade red pigment used as a polishing agent for glass, jewelry, etc.
A cosmetic prepared from dried flowers of the saf- flower.
A black solid prepared by passing either steam or carbon dioxide over redhot iron.
Iron oxide brown may also be prepared by passing steam over heated iron(II) sulfide.
Iron oxide brown occurs in nature as the mineral magnetite.
Iron oxide brown is insoluble in water but will dissolve in acids to give a mixture of iron(II) and iron(III) salts in the ratio 1:2.
Generally Iron oxide brown is chemically unreactive; it is, however, a fairly good conductor of electricity.
Iron oxide brown occurs in nature as the mineral hematite.
Iron oxide brown is the principal ore of iron from which the metal and its alloys are produced.
Also, this oxide occurs in the mineral, limonite, 2Fe2O33H2O.
An important application of iron oxide brown involves producing red, orange, and yellow pigments.
Other applications are in coatings for metals, steel and rubber; in ceramics; and as a catalyst for oxidation reactions.
Iron oxide brown Chemical Properties
Melting point: 1538°C
Density: 5.24
Fp: >230 °F
Storage temp.: 2-8°C
Solubility: Iron oxide brown is soluble In Warm Hydrochloric Acid, Slightly Soluble in Sulfuric Acid.
Form: pieces
Color: black
Specific Gravity: 5.1～5.2
PH: 3.7±0.3
Water Solubility: INSOLUBLE
Merck: 14,4028
Exposure limits: ACGIH: TWA 5 mg/m3
OSHA: TWA 10 mg/m3; TWA 15 mg/m3; TWA 5 mg/m3
NIOSH: IDLH 2500 mg/m3; TWA 5 mg/m3
Stability: Stable.
CAS DataBase Reference: 1309-37-1(CAS DataBase Reference)
NIST Chemistry Reference: Iron oxide brown (1309-37-1)
IARC: 3 (Vol. 1, Sup 7) 1987
EPA Substance Registry System: Iron oxide brown (1309-37-1)
Reddish-brown hexagonal crystal; refractive index 2.91; density 5.25g/cm3; Moh’s hardness 6.0; melts at 1565°C; insoluble in water; dissolves in acids.
Iron oxide brown is a noncombustible, black to black red or brick-red mineral (iron ore) composed mainly of ferric oxide, Fe2O3.
Uses
Iron oxide brown occurs in nature as the mineral hematite.
Iron oxide brown is the principal ore of iron from which the metal and its alloys are produced.
Also, Iron oxide brown occurs in the mineral, limonite, 2Fe2O3•3H2O.
An important application of Iron oxide brown involves producing red, orange, and yellow pigments.
Other applications are in coatings for metals, steel and rubber; in ceramics; and as a catalyst for oxidation reactions.
As pigment for rubber, paints, paper, linoleum, ceramics, glass; in paint for ironwork, ship hulls; as polishing agent for glass, precious metals, diamonds; in electrical resistors and semiconductors; in magnets, magnetic tapes; as catalyst; colloidal solutions as stain for polysaccharides.
Iron oxide brown is a nutrient and dietary supplement that is a source of iron.
Iron oxide brown is an inorganic pigment of either natural or synthetic origin.
Iron oxide brown is a low chroma red with excellent durability and low cost.
Iron oxide brown is made by heating iron sulfate with quicklime in a furnace.
The second preparatory technique involves calcining iron sulfate in the presence of air at high temperatures.
Natural and oxides of iron are mined either as the mineral hematite (Fe2O3) or as hematite in Iron oxide brown's hydrated form.
Reactions
Ferric oxide decomposes to Iron oxide brown's elements when heated at elevated temperatures:
2Fe2O3 → 4Fe + 3O2
Iron oxide brown is reduced by most reducing agents.
Reaction with carbon monoxide at elevated temperatures (that occurs in the blast furnace) gives metallic iron.
The overall reaction is mildly exothermic (ΔHrxn –113.4 kcal/mol):
2 Fe2O3 + 6CO → 4Fe + 6CO2
Iron oxide brown also is reduced by powdered aluminum at elevated temperatures, forming aluminum oxide and metallic iron:
Fe2O3 + 2Al → Al2O3 + 2Fe
The reaction is highly exothermic and becomes self-sustaining after ignition.
When heated with sand in an electric furnace, Iron oxide brown forms ferrosilicon alloy.
When heated in a vacuum at 1,000°C, Iron oxide brown forms triiron tetroxide, Fe3O4.
Preparation
Iron oxide brown is prepared as a reddish-brown hydrated precipitate by treating an aqueous solution of an iron(III) salt with caustic soda:
2FeCl3 + 6NaOH → Fe2O3•3H2O + 6NaCl
Iron oxide brown also is obtained by thermal decomposition of iron(II) sulfate or the brown oxide hydroxide:
2FeSO4 → Fe2O3 + SO2 + SO3
2FeO(OH) → Fe2O3 + H2O
Iron oxide brown is prepared in industrial scale by first precipitating iron(II) hydroxide Fe(OH)2 by treating aqueous solutions of iron(II) sulfate and caustic soda.
The Fe(OH)2 is then oxidized to iron(III) hydroxide by aeration.
The latter is dehydrated by heating:
Fe2+ (aq) + OH¯ (aq) → Fe(OH)2(s) → 2Fe(OH)3 → Fe2O3 + 3H2O
Iron oxide brown also is produced by ignition of iron(III) oxalate and iron carbonyls:
2Fe2(C2O4)3 +3O2 → 2Fe2O3 + 12CO
Synonyms:
Ferric oxide(II,III), magnetic nanoparticles solution;
Ferric(III) oxide;
Iron(III) oxide, 99% trace metals basis;
Iron(III) oxide, 99.9% trace metals basis;
Iron(III) oxide, 98% trace metals basis;
Iron(III) oxide, 99.95% trace metals basis;
Iron(III) oxide, 99.99% trace metals basis;
Iron(lll) oxide
