Cadmium oxide

Description

Cadmium oxide forms brownish-red crystalsor a yellow to dark brown amorphous powder. Molecularweight=128.4; Freezing/Melting point=900℃ (slowdecomposition begins at 700℃); Sublimation point 51559℃. Hazard Identification (based on NFPA-704 MRating System): Health 3, Flammability 0, Reactivity 0.Very slightly soluble in water.

Chemical properties

dark brown powder or crystals

Chemical properties

Cadmium fume (as Cd) is fi nely divided solid particles dispersed in air.

Chemical properties

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

Physical properties

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.

The Uses of Cadmium oxide

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.

The Uses of Cadmium oxide

In phosphors, semiconductors; manufacture of silver alloys, glass; in storage battery electrodes; as nematocide; as catalyst for organic reactions, in cadmium electroplating; in ceramic glazes.

The Uses of Cadmium oxide

This is used for cadmium plating baths, electrodes for batteries (cells), ceramic glazes, and insecticides. CdO is a deadly poison and carcinogen.

Production Methods

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

Preparation

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

General Description

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.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Cadmium oxide reacts violently with magnesium.

Hazard

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

Health Hazard

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.

Health Hazard

Exposure to cadmium fume causes adverse health effects among occupational workers. The symptoms of toxicity and poisoning include, but are not limited to, pulmonary edemadyspnea, coughing, tight chest, substernal pain, headaches, chills, muscle aches, nausea, vomiting, diarrhea, emphysema, proteinuria, anosmia, and mild anemia. Exposures also cause kidney and lung damage

Fire Hazard

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.

Safety Profile

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.

Potential Exposure

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

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.Medical observation is recommended for 24-48 h afterbreathing overexposure, as pulmonary edema may bedelayed. As first aid for pulmonary edema, a doctor orauthorized paramedic may consider administering a corticosteroid spray.Note to Physician: In case of fume inhalation, treat pulmonary edema. Give prednisone or other corticosteroid orallyto reduce tissue response to fume. Positive-pressure ventilation may be necessary. Treat metal fume fever with bedrest, analgesics, and antipyretics. The symptoms of metalfume fever may be delayed for 4-12 h following exposure:it may last less than 36 h.Note to physician: For severe poisoning do not useBAL [British Anti-Lewisite, dimercaprol, dithiopropanol(C3H8OS2)] as it is contraindicated or ineffective inpoisoning from cadmium.

storage

Color Code—Blue: Health Hazard: Store in asecure poison location. Prior to working with cadmiumoxide you should be trained on its proper handling and storage. Store in tightly closed containers in a cool,well-ventilated area, away from magnesium, oxidizers,combustible materials, heat, moisture, and acids. Where thischemical is used, handled, manufactured, or stored, useexplosion-proof electrical equipment and fittings. A regulated, marked area should be established where this chemical is handled, used, or stored in compliance with OSHAStandard 1910.1045.

Shipping

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

Incompatibilities

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

Waste Disposal

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