Железа (III) оксид

Описание

Iron 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.

Химические свойства

Hematite is a noncombustible, black to black red or brick-red mineral (iron ore) composed mainly of ferric oxide, Fe2O3. Ferric oxide

Вхождение

Iron(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, 2Fe₂O₃?3H₂O. 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.

Использование

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

Подготовка

Iron(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 → Fe₂O₃?3H₂O + 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
.

Определение

A high-grade red pigment used as a polishing agent for glass, jewelry, etc. (2) A cosmetic prepared from dried flowers of the saf- flower.

Опасность

Pneumoconiosis. Questionable carcinogen.

Возможный контакт

Hematite; as an iron ore composed mainly of ferric oxide, is a major source of iron and is used as a pigment for rubber, paints, paper, linoleum, ceramics, dental restoratives; and as a polishing agent for glass and pre cious metals. It is also used in electrical resistors, semiconduc tors, magnets, and as a catalyst. Human exposure to hematite from underground hematite mining is principally through inhalation and/or ingestion of dusts. No estimates are available concerning the number of underground miners exposed.

Канцерогенность

Welders are typically exposed to a complex mixture of dust and fume of metallic oxides, as well as irritant gases, and are subject to mixeddust pneumoconiosis with possible loss of pulmonary function; this should not be confused with benign pneumoconiosis caused by iron oxide.1 Although an increased incidence of lung cancer has been observed among hematite miners exposed to iron oxide, presumably owing to concomitant radon gas exposure, there is no evidence that iron oxide alone is carcinogenic to man or animals.6

Несовместимости

Contact with hydrogen peroxide, ethyl ene oxide, calcium hypochlorite will cause explosion. Violent reaction with powdered aluminum; hydrazine, hydrogen trisulfide.