Dieisentrioxid

BeschreibungIron oxides 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 oxides are primarily distinguished from technical grades by the comparatively low levels of contamination by other metals. This 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 oxides have been used to color confectionery, fillings and decorations for pastry products, cheese products, fish paste, pet foods, cosmetics and pharmaceutical products.

OccurrenceIron(III) oxide occurs in nature as the mineral hematite. It 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 this compound 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.

VerwendenFerric Oxide is a nutrient and dietary supplement that is a source of iron.

synthetischeIron(III) oxide is prepared as a reddish-brown hydrated precipitate by treating an aqueous solution of an iron(III) salt with caustic soda: 2FeCl3 + 6NaOH → Fe2O33H2O + 6NaCl It also is obtained by thermal decomposition of iron(II) sulfate or the brown oxide hydroxide: 2FeSO4 → Fe2O3 + SO2 + SO3 2FeO(OH) → Fe2O3 + H2O The oxide 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) + OHˉ (aq) → Fe(OH)2(s) → 2Fe(OH)3 → Fe2O3 + 3H2O It also is produced by ignition of iron(III) oxalate and iron carbonyls: 2Fe2(C2O4)3 +3O2 → 2Fe2O3 + 12CO.