ChemicalBook CAS DataBase List 7440-43-9

7440-43-9

Name	CADMIUM
CAS	7440-43-9
EINECS(EC#)	231-152-8
Molecular Formula	Cd
MDL Number	MFCD00010914
Molecular Weight	112.41
MOL File	7440-43-9.mol

Chemical Properties

Description	Cadmium is a grey-white, soft, blue-white malleable, lustrous metal. It is insoluble in cold water, hot water, methanol, diethyl ether, and n-octanol. It is stable and incompatible with strong oxidising agents, nitrates, nitric acid, selenium, and zinc, and the powdered metal may be pyrophoric and flammable. Cadmium is associated with occupations such as industrial processes, metal plating, and production of nickel– cadmium batteries, pigments, plastics, and other synthetics. Cadmium metal is produced as a by-product from the extraction, smelting, and refining of the non-ferrous metals zinc, lead, and copper. In view of the unique properties, cadmium metal and cadmium compounds are used as pigments, stabilisers, coatings, specialty alloys, and electronic compounds. less more
Definition	Metallic element of atomic number 48, group IIB of the periodic table.Valence 2. There are eight stable isotopes.
Appearance	Cadmium is a bluish-white metal.
Melting point	321 °C
Boiling point	765 °C(lit.)
density	8.65 g/mL at 25 °C(lit.)
vapor pressure	1.3 hPa (394 °C)
storage temp.	>15°C-
solubility	8.2mg/l insoluble
form	wire
color	Silvery white
Specific Gravity	8.642
Odor	Odorless
Stability:	Stable. Incompatible with strong oxidizing agents, nitrates, nitric acid, selenium, zinc. Flammable. Powdered metal may be pyrophoric.
Resistivity	7.27 μΩ-cm, 22°C
Water Solubility	insoluble H2O; reacts with dilute HNO3, slowly with hot HCl [MER06]
Merck	13,1613
BRN	8137359
Exposure limits	TLV-TWA 0.05 mg/m³ (for dusts and salts) (ACGIH), 0.2 mg/m³ (MSHA), 0.1 mg/m³ (OSHA), lowest feasible level in air (NIOSH); ceiling 0.3 mg/m³ (OSHA).
History	Cadmium was discovered by Stromeyer in 1817 from an impurity in zinc carbonate. Cadmium most often occurs in small quantities associated with zinc ores, such as sphalerite (ZnS). Greenockite (CdS) is the only mineral of any consequence bearing cadmium. Almost all cadmium is obtained as a by-product in the treatment of zinc, copper, and lead ores. Cadmium is a soft, bluish-white metal which is easily cut with a knife. It is similar in many respects to zinc. It is a component of some of the lowest melting alloys; it is used in bearing alloys with low coefficients of friction and great resistance to fatigue; it is used extensively in electroplating, which accounts for about 60% of its use. Cadmium is also used in many types of solder, for standard E.M.F. cells, for Ni-Cd batteries, and as a barrier to control atomic fission. The market for Ni- Cd batteries is expected to grow significantly. Cadmium compounds are used in black and white television phosphors and in blue and green phosphors for color TV tubes. It forms a number of salts, of which the sulfate is most common; the sulfide is used as a yellow pigment. Cadmium and solutions of its compounds are toxic. Failure to appreciate the toxic properties of cadmium may cause workers to be unwittingly exposed to dangerous fumes. Some silver solders, for example, contain cadmium and should be handled with care. Serious toxicity problems have been found from long-term exposure and work with cadmium plating baths. Cadmium is present in certain phosphate rocks. This has raised concerns that the long-term use of certain phosphate fertilizers might pose a health hazard from levels of cadmium that might enter the food chain. In 1927 the International Conference on Weights and Measures redefined the meter in terms of the wavelength of the red cadmium spectral line (i.e., 1 m = 1,553,164.13 wavelengths). This definition has been changed (see under Krypton). The current price of cadmium is about 50￠/g (99.5%). It is available in high purity form for about $550/kg. Natural cadmium is made of eight isotopes. Thirty-four other isotopes and isomers are now known and recognized.
Uses	A soft bluish metal, cadmium is extremely toxic, particularly in the compounds used for photography. It is found in zinc ores and in the mineral greenockite (CdS). less more
CAS DataBase Reference	7440-43-9(CAS DataBase Reference)
IARC	1 (Vol. 58, 100C) 2012
EPA Substance Registry System	Cadmium (7440-43-9)

Safety Data

Hazard Codes	T,N,T+,F,Xi
Risk Statements	R45:May cause cancer. R50/53:Very Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment . R68:Possible risk of irreversible effects. R63:Possible risk of harm to the unborn child. R62:Possible risk of impaired fertility. R48/23/25:Toxic: danger of serious damage to health by prolonged exposure through inhalation and if swallowed . R26:Very Toxic by inhalation. R17:Spontaneously flammable in air. R36/38:Irritating to eyes and skin . R20/21/22:Harmful by inhalation, in contact with skin and if swallowed . less more
Safety Statements	S53:Avoid exposure-obtain special instruction before use . S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) . S61:Avoid release to the environment. Refer to special instructions safety data sheet . S60:This material and/or its container must be disposed of as hazardous waste . S43:In case of fire, use ... (indicate in the space the precise type of fire-fighting equipment. If water increases the risk add-Never use water) . S7/8:Keep container tightly closed and dry . S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice . less more
RIDADR	UN 3082 9/PG 3
WGK Germany	3
RTECS	EU9800000
TSCA	Yes
HS Code	8107 20 00
HazardClass	8
PackingGroup	III
storage	Cadmium should be kept stored in a tightly closed container in a cool place. It should be kept stored in a separate locked safety storage cabinet
Precautions	On exposures to cadmium, wash the skin immediately with plenty of water and a nonabrasive soap. Workers should cover the exposed skin with an emollient.
Safety Profile	Confirmed human carcinogen with experimental carcinogenic, tumorigenic, and neoplastigenic data. A human poison by inhalation and possibly other routes. Poison experimentally by ingestion, inhalation, intraperitoneal, less more
Hazardous Substances Data	7440-43-9(Hazardous Substances Data)
Toxicity	A metal that is used for electroplating and in batteries, as a color pigment for paints and as a stabilizer in plastics. The oral LD50 in rats is about 0.88 mg/kg and the LC50 in fathead minnows is about 3.06 mg/L. Cadmium is a nephrotoxicant and hepatotoxicant, probably acting by displacement and substitution of essential metals in proteins and enzymes. In humans acute poisoning can cause nausea and vomiting, diarrhea, headache, muscular aches, salivation, abdominal pain, and shock. In acute poisoning, unabsorbed cadmium is removed by catharsis. less more
IDLA	9 mg Cd/m3

Raw materials And Preparation Products

Hazard Information

Chemical Properties

Cadmium is a gray-white, soft, malleable, lustrous metal or a grayish-white powder. It is insoluble in cold water, hot water, methanol, diethyl ether, and n-octanol. It is stable, incompatible with strong oxidizing agents, nitrates, nitric acid, selenium, zinc, and the powdered metal may be pyrophoric and flammable. Cadmium is associated with occupations such as industrial processes, metal plating, production of nickel-cadmium batteries, pigments, plastics, and other synthetics. Cadmium metal is produced as a by-product from the extraction, smelting, and refi ning of the non-ferrous metals zinc, lead, and copper. In view of its unique properties, cadmium metal and cadmium compounds are used as pigments, stabilizers, coatings, specialty alloys, and as electronic compounds.

General Description

Silver-white blue tinged lustrous metallic solid.

Reactivity Profile

A violent explosion occurred 30 minutes after placement of a CADMIUM rod into hydrazoic acid [Mellor 8 Supp. 2:50 1967]. Fused ammonium nitrate with powdered metal often produces a violent explosive reaction. Reactivity similar to zinc. May be incompatible with oxidants.

Air & Water Reactions

The finely divided metal is pyrophoric. Slowly oxidized by moist air to form CADMIUM(7440-43-9) oxide. Insoluble in water.

Hazard

Flammable in powder form. Toxic by inhalation of dust or fume. A carcinogen. Cad- mium plating of food and beverage containers has resulted in a number of outbreaks of gastroenteritis (food poisoning). Soluble compounds of cadmium are highly toxic; however, ingestion usually induces a strong emetic action that minimizes the risk of fatal poisoning. Use as fungicide may be restricted. Kidney damage. Confirmed carcinogen.

Health Hazard

Cadmium is hazardous in case of ingestion and inhalation, slightly hazardous in case of skin contact, causing allergic reactions, irritant to the skin and eyes, and a sensitizer. Human exposures to cadmium cause nausea, vomiting, abdominal cramping, diarrhea, increased salivation, hemorrhagic gastroenteritis, headache, dizziness, cough, dyspnea, chills (metal fume fever), alopecia, anemia, arthritis, cirrhosis of the liver, renal cortical necrosis, and cardiomyopathy. Acute inhalation of cadmium causes nasopharyngeal irritation, chest pain, enlarged heart, pulmonary edema, pulmonary fi brosis, emphysema, bronchiolitis, alveolitis, and renal cortical necrosis, particularly proximal tubule cell necrosis. Prolonged period of exposure to high concentrations of cadmium causes adverse effects to the skeletal system, arthritis, cardiovascular system/hypertension, and severe over-exposure can result in death

Potential Exposure

Cadmium is a highly corrosion resistant and is used as a protective coating for iron, steel, and copper; it is generally applied by electroplating, but hot dipping and spraying are possible. Cadmium may be alloyed with copper, nickel, gold, silver, bismuth, and aluminum to form easily fusible compounds. These alloys may be used as coatings for other materials; welding electrodes, solders, etc. It is also utilized in electrodes of alkaline storage batteries, as a neutron absorber in nuclear reactors, a stabilizer for polyvinyl chloride plastics, a deoxidizer in nickel plating; an amalgam in dentistry; in the manufacture of fluorescent lamps, semiconductors,photocells, and jewelry, in process engraving, in the automobile and aircraft industries; and to charge Jones reductors. Various cadmium compounds find use as fungicides, insecticides, nematocides, polymerization catalysts, pigments, paints, and glass; they are used in the photographic industry and in glazes. Cadmium is also a contaminant of superphosphate fertilizers. Human exposure to cadmium and certain cadmium compounds occurs through inhalation and ingestion. The entire population is exposed to low levels of cadmium in the diet because of the entry of cadmium into the food chain as a result of its natural occurrence. Tobacco smokers are exposed to an estimated 17 μg/cigarette. Cadmium is present in relatively low amounts in the earth’s crust; as a component of zinc ores, cadmium may be released into the environment around smelters

Fire Hazard

Flammable in powder form. Combustible.

First aid

Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin. Keep victim warm and quiet. Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy.

Shipping

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

Incompatibilities

Air exposure with cadmium powder may cause self-ignition. Moist air slowly oxidizes cadmium forming cadmium oxide. Cadmium dust is incompatible with strong oxidizers, ammonium nitrate; elemental sulfur; hydrazoic acid; selenium, zinc, tellurium. Contact with acids cause a violent reaction, forming flammable hydrogen gas.

Waste Disposal

With cadmium compounds in general, precipitation from solution as sulfides, drying and return of the material to suppliers for recovery is recommended. Cadmium may be recovered from battery scrap as an alternative to disposal. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Must be disposed properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office.

Physical properties

Cadmium is a soft, blue-white metal that is malleable and ductile although it becomesbrittle at about 80°C. It is also found as a grayish-white powder. It is considered rare and isseldom found by itself as an ore. Its melting point at 320.9°C is considered low. Its boilingpoint is 765°C, and its density is 8.65 g/cm³. Certain alloys of cadmium have extremely lowmelting points at about 70°C.

Isotopes

There are 52 isotopes of cadmium. Forty-four are radioactive and artificiallyproduced, ranging from Cd-96 to Cd-131. Of these 52 isotopes, there are five stableisotopes plus three naturally occurring radioactive isotopes with extremely long half-livesthat are considered as contributing to the element’s natural occurrence in the Earth’scrust. The three naturally radioactive isotopes (Cd-106, Cd-113, and Cd-116) are thelongest known beta emitters. They are two million years older than when the solar systemwas formed about 4.5 billion years ago. The five stable isotopes and their proportionalcontributions to the element’s existence on Earth are as follows: Cd-108 = 0.89%,Cd-110 = 12.49%, Cd-111= 12.80%, Cd-112 = 24.13%, and Cd-114 = 28.73%.

Origin of Name

The word cadmium is from the Latin word cadmia or the Greek word kadmeia, meaning the zinc oxide ore “calamine” that contains the element cadmium.

Occurrence

Cadmium is considered a rare element even though it is widely distributed over the Earth’scrust. Its estimated abundance in the Earth’s crust is 1.10^-1 milligrams per kilogram. It is consideredthe 65th most abundant element, but it does not occur as a free metal in nature. It isusually found in relationship with other metallic ores. Its abundance is only about 1/1000ththat of zinc. It is found in an ore called greenockite, which is cadmium sulfite (CdS). This oredoes not have a high enough concentration of cadmium to be mined profitably. Cadmiumis found along with zinc, lead, and copper ores. Today, most cadmium is obtained as a byproductfrom the processing and refining of zinc ores. In addition, dust and fumes from roastingzinc ores are collected by an electrostatic precipitator and mixed with carbon (coke) andsodium or zinc chloride. This residue is then treated to recover the cadmium. Other refiningprocesses can obtain up to 40% recovery of cadmium from zinc ores.
Greenockite ore, as well as zinc and other ores, which produce cadmium as a by-product,are found in many countries, including Australia, Mexico, Peru, Zaire, Canada, Korea, andBelgium-Luxembourg and in the central and western United States.

Characteristics

Although cadmium is not considered a transition element in some periodic tables, it is thecentral element of the triad with zinc and mercury. Zinc is just above it and mercury is below itin group 12 of the periodic table. Cadmium’s chemical and physical properties are similar to itsgroup 12 mates. Their electronegativity is very similar: Zn = 1.6, Cd = 1.7, and Hg = 1.9.
Cadmium is resistant to alkalis, but is soluble in acids, mainly nitric acid. Although it isused to electroplate steel to prevent corrosion, it will tarnish in moist air.

Preparation

Cadmium often produces together with Zinc (Zn). The first output part is gathered at the distillation, using the lower boiling point of Cd than that of Zn. Redistillation purifies the material. The Czochralski and horizontal Stockbarger methods are used to grow a single crystal, after melting has taken place.
Thin films are deposited by vacuum evaporation using direct heating in a conical, basket-type heater made of chromel, Nb, Ta, W, Ni, or Fe, or in a Mo or Ta boat. External heating of an alumina crucible with a W heater is also possible. It is also possible to heat an iron crucible externally using a nichrome heater. The evaporation rate at 264 ℃ (sublimation) is 2.67×10^-4 g/cm² s.

Production Methods

Two major processes are used for producing cadmium: (1) pyro-hydro-metallurgical and (2) electrolytic. Zinc blende is roasted to eliminate sulfur and to produce a zinc oxide calcine. The latter is the starting material for both processes. In the pyro-hydro-metallurgical process, the zinc oxide calcine is mixed with coal, pelletized, and sintered. This procedure removes volatile elements such as lead, arsenic, and the desired cadmium. From 92 94% of the cadmium is removed in this manner, the vapors being condensed and collected in an electrostatic precipitator. The fumes are leached in H2SO4 to which iron sulfate is added to control the arsenic content. The slurry then is oxidized, normally with sodium chlorate, after which it is neutralized with zinc oxide and filtered. The cake goes to a lead smelter, while the filtrate is charged with highpurity zinc dust to form zinc sulfate or zinc carbonate and cadmium sponge. The latter is briquetted to remove excess H2O and melted under caustic to remove any zinc. The molten metal then is treated with zinc ammonium chloride to remove thallium, after which it is cast into various cadmium metal shapes. The process just described is known as the melting under caustic process. In a distillation process, regular rather than high-purity zinc is used to make the sponge. Then, after washing and centrifuging to remove excess H2O, the sponge is charged to a retort. The heating and distillation process is under a reducing atmosphere. Lead and zinc present in the vapors contaminate about the last 15% of the distillate. Thus, a redistillation is required. The cadmium vapors produced are collected and handled as previously described.

Purification Methods

Any oxide contaminant is removed by filtering the molten metal, under vacuum, through quartz wool. Its solubility in Hg is 5.2% (18o), and it is soluble in mineral acids. [Wagenknecht & Juza in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1092 1965.]

Industrial uses

Cadmium (symbol Cd) is a silvery-white crystallinemetal that has a specific gravity of 8.6,is very ductile, and can be rolled or beaten intothin sheets. It resembles tin and gives the samecharacteristic cry when bent, but is harder thantin. A small addition of zinc makes it very brittle.It melts at 320°C and boils at 765°C. Cadmiumis employed as an alloying element insoft solders and in fusible alloys, for hardeningcopper, as a white corrosion-resistant platingmetal, and in its compounds for pigments andchemicals. It is also used for Ni–Cd batteriesand to shield against neutrons in atomic equipment;but gamma rays are emitted when theneutrons are absorbed, and these rays requirean additional shielding of lead.
Most of the consumption of cadmium is forelectroplating. For a corrosion-resistant coatingfor iron or steel a cadmium plate of 0.008 mmis equal in effect to a zinc coat of 0.025 mm.The plated metal has a silvery-white color witha bluish tinge, is denser than zinc, and harderthan tin, but electroplated coatings are subjectto H2 embrittlement, and aircraft parts are usuallycoated by the vacuum process. Cadmiumplating is not normally used on copper or brasssince copper is electronegative to it, but whenthese metals are employed next to cadmium-plated steel a plate of cadmium may beused on the copper to lessen deterioration.

Carcinogenicity

Cadmium and cadmium compounds are known to be human carcinogens based on sufficient evidence of carcinogenicity from studies in humans, including epidemiological and mechanistic studies. Cadmium and cadmium compounds were first listed as reasonably anticipated to be human carcinogens in the First Annual Report on Carcinogens in 1980, based on sufficient evidence of carcinogenicity from studies in experimental animals. The listing was revised to known to be human carcinogens in the Ninth Report on Carcinogens in 2000.

Environmental Fate

Cadmium inhibits plasma membrane calcium channels and Ca2t-ATPases. It also inhibits repair of DNA damaged by various chemicals, an effect which is believed to be associated with the induction of tumors. Although cadmium forms a metallothionein, the preformed cadmium metallothionein is nephrotoxic (toxic to the kidneys); it is suggested that effects occur when, at some stage in the kidney, the cadmium is dissociated from the metallothionein. In Itai-Itai disease (see Human under Chronic Toxicity section), patients were found to have chromosome abnormalities.
Cadmium has an affinity for sulfhydryl groups, and hence can inhibit enzymes; however, cells treated with cadmium showed proliferation of peroxisomes, which contain catalase, an enzyme. It appears that cadmium at first inhibits catalase activity and then, after a time, enhances that activity. In addition, cadmium inhibits enzymes involved in gluconeogenesis (the generation of glycogen for energy production from noncarbohydrate precursors). It also inhibits oxidative phosphorylation (energy production) and depresses trypsin inhibitor capacity.

Structure and conformation

The space lattice of Cadmium belongs to the hexagonal system, and its closely-packed hexagonal lattice has lattice constants of a=0.2973 nm and c=0.5607 nm.

Toxicity evaluation

As indicated in the Exposure and Exposure Monitoring section, cadmium is widely distributed in the environment from a variety of natural and anthropogenic sources. Cadmium emitted into the air is often found bound to small particulates and can travel with these particulates over long distances. As a result, cadmium can remain in the atmosphere for long periods of time until it is deposited by gravitational settling or in rain and snow. Cadmium tends to be more mobile in water than other heavy metals although it will complex with humic substances and can precipitate out under certain conditions. Cadmium can bioaccumulate in aquatic organisms; the degree of accumulation is associated with the pH and humic content of the water. It can also bioaccumulate in plants and in the animals that feed on these plants; for example, cattle and wildlife. However, terrestrial bioaccumulation is much lower than that in water and cadmium concentrations at the top of the terrestrial food chain are not much higher than those at the lower end of the chain.

Material Safety Data Sheet(MSDS)

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