Кадмия окись

Химические свойства

Cadmium oxide forms brownish-red crystals or a yellow to dark brown amorphous powder.

Физические свойства

Occurs in two forms, alpha form—a colorless amorphous powder, and beta form—a reddish-brown crystal; density 6.95 g/cm³ (alpha form) and 8.15 g/cm³ (beta form); decomposes on rapid heating at 900°C; sublimation temperature 1,559°C; insoluble in water and alkalis; dissolves in mineral acids.

Использование

Cadmium oxide is used as an electroplating chemical, catalyst, component of semiconductors, and starting material for PCV heat stabilizers; in glass and ceramic glazes; for production of cadmium electrodes in storage batteries; and in other applications.

Методы производства

Cadmium oxide is manufactured commercially by distilling cadmium metal from graphite retort and allowing vapor to react with air.

Подготовка

Cadmium oxide is prepared by the reaction of cadmium vapor with oxygen. The metal is first melted in a steel retort and transported into a heated chamber where it is vaporized. The vapor is reacted with air, and the cadmium oxide formed is collected in a bag house. The particle size of the product depends on the ratio of air to cadmium vapor. The oxide may be further purified and particles of uniform size may be obtained by calcination at low red heat.
Cadmium oxide also may be prepared by several other routes starting with various cadmium salts. The compound can be made by thermal decomposition of cadmium carbonate or cadmium hydroxide:
CdCO₃ → CdO + CO₂
Cd(OH)₂ → CdO + H₂O
Similar thermal decomposition of cadmium nitrate or sulfate would yield the oxide.
he oxide. Cadmium oxide also may be made by high temperature oxidation of cadmium sulfide:
2CdS + 3O₂ → 2CdO + 2SO₂
Finely divided oxide may be obtained by pyrolysis of cadmium salts of carboxylic acids, such as cadmium formate or oxalate.
(COOH)₂Cd → CdO + H₂O + 2CO
(COO)₂Cd → CdO + CO₂ + CO

Общее описание

Brown crystals or brown amorphous powder. Used as an electroplating chemical and in the manufacture of cadmium electrodes. Is a component of silver alloys, phosphors, semiconductors, glass and ceramic glazes. Formerly used by veterinarians to kill worms and parasites.

Реакции воздуха и воды

Insoluble in water.

Профиль реактивности

Cadmium oxide reacts violently with magnesium.

Опасность

Inhalation of vapor or fume may be fatal. A confirmed carcinogen.

Угроза здоровью

The lethal inhalation dose of Cadmium oxide in humans is 2,500 mg/m3 for a 1 minute exposure. Lethal exposure has been established at 50 mg (cadmium)/m3 for 1 hour for Cadmium oxide dust and 1/2 hour for the fume. These concentrations may be inhaled without sufficient discomfort to warn worker of exposure. Inhalation may cause acute tracheobronchitis, pneumonitis, and pulmonary edema. Exposure can cause kidney and lung damage. Acute exposure by inhalation may cause death by anoxia. The lowest human toxic inhalation concentration is 8.630 mg/m3/5 hours for the fume. Persons with respiratory disorders should be excluded from contact with Cadmium oxide.

Пожароопасность

When heated to decomposition, Cadmium oxide emits toxic fumes of cadmium. (Non-Specific -- Cadmium Compounds) Fire may produce irritating or poisonous gases. Runoff from fire control or dilution water may cause pollution. Oxides of cadmium react explosively with magnesium when heated.

Профиль безопасности

Confirmed human carcinogen with experimental neoplastigenic data. Poison by ingestion, inhalation, and intraperitoneal routes. An experimental teratogen. Other experimental reproductive effects. Human systemic effects by inhalation include: change in the sense of smell, change in heart rate, blood pressure increase, an excess of protein in the urine, and other kidney or bladder changes. Mixtures with magnesium explode when heated. When heated to decomposition it emits toxic fumes of Cd. See also CADMIUM COMPOUNDS.

Возможный контакт

Cadmium oxide is used as an electroplating chemical and in the manufacture of semiconductors and cadmium electrodes; synthesis of other cadmium salts; a component of silver alloys, phosphorus, glass and ceramic glazes, semiconductors, and batteries. Used as a vermicide

Перевозки

UN2570 Cadmium compounds, Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required.

Несовместимости

Oxides of cadmium react explosively with magnesium, especially when heated. Heat above 700C causes slow decomposition. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); light metals: contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, hydrogen sulfide, hydrazine nitrate. May ignite combustibles, such as wood, paper, oil, etc

Утилизация отходов

Form nitrate with HNO3, precipitate with H2S, filter, package and return to supplier.