7440-43-9 Usage
Uses
Used in Electronics and Optics:
Cadmium is used as a component in low-melting-point alloys to make solders, which are used to join electrical junctions and other specialized metallic components. Precautions are required since it is a toxic substance.
Used in Automotive and Manufacturing Industry:
Cadmium is used as a component in long-wearing bearings and as a thin coating for steel to prevent corrosion.
Used in Nuclear Industry:
Cadmium is a neutron absorber, making it useful as control rods in nuclear reactors. The rods are raised to activate the reactor and then lowered into the reactor to absorb neutrons that halt the fission reaction.
Used in Battery Industry:
Cadmium, along with nickel, forms a nickel-cadmium alloy used to manufacture "nicad" batteries that are shaped the same as regular small dry-cell batteries.
Used in Electroplating:
Cadmium is used in electroplating, providing a corrosion-resistant coating for iron or steel. A cadmium plate of 0.008 mm is equal in effect to a zinc coat of 0.025 mm.
Used in Pigments and Chemicals:
Cadmium compounds have numerous applications, including dyeing and printing textiles, as TV phosphors, as pigments and enamels, and in semiconductors and solar cells.
Used in Alloys:
Cadmium is used in the production of various alloys, such as Lichtenberg's, Abel's, Lipowitz', Newton's, and Wood's metal, which have extremely low melting points and are used in soft solder and solder for aluminum.
Used in Photography:
Cadmium is used in photography, particularly in the compounds used for this application, although it is highly toxic in this context.
Used in Catalysts:
Cadmium is used as a hardener for copper and as a catalyst in various industrial processes.
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.
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.
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.
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.
Air & Water Reactions
The finely divided metal is pyrophoric. Slowly oxidized by moist air to form CADMIUM oxide. Insoluble in water.
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.
Hazard
Cadmium powder, dust, and fumes are all flammable and toxic if inhaled or ingested.Cadmium and many of its compounds are carcinogenic.Severe illness and death can occur from exposure to many cadmium compounds. It isabsorbed in the gastrointestinal tract. However, it can be eliminated in the urine and fecesin young, healthy people.
Health Hazard
There are several reports of cadmium poisoningand human death. Cadmium can enterthe body by inhalation of its dusts or fumes,or by ingestion. In humans the acute toxicsymptoms are nausea, vomiting, diarrhea,headache, abdominal pain, muscular ache,salivation, and shock. In addition, inhalationof its fumes or dusts can cause cough,tightness of chest, respiratory distress, congestionin lungs, and bronchopneumonia. A30-minute exposure to about 50 mg/m3 of itsfumes or dusts can be fatal to humans. Theoral LD50 value in rats is within the range of250 mg/kg.Cadmium is a poison that is accumulatedin the liver and kidneys. Thus, chronicpoisoning leads to liver and kidney damage.It is very slowly excreted. Its biologicalhalf-life in humans is estimated atabout 20–30 years (Manahan 1989). Cadmiumlevel in the kidney at 200 μg/g,can damage proximal tubules, resulting intheir inability to reabsorb small-moleculeproteins, such as β2-microglobulin (Luand Kacey 2003). Cigarette smoking andcalcium-deficient diet enhance its toxicity.Renal toxicity may occur in human subjectsas a result of chronic ingestion of low-leveldietary Cd. The absorption of this metal,however, through the GI tract is low. Cadmiumis also known to produce the so-calleditai-itai disease, which is a chronic renaldisease, producing bone deformity and kidneymalfunction. Cadmium, similar to otherheavy meals, binds to the sulfhydryl (-SH)groups in enzymes, thus inhibiting enzymaticacitivity. Intramuscular administrationof cadmium produced tumors in the lungs and blood in rats. There is sufficient evidenceof its carcinogenicity in animals.Data on accumulation of Cd in human kidneyand liver have been reviewed by Sataruget al. (2000). Epidemiological and autopsystudies have shown a relationship betweenthe tubular dysfunction and kidney Cd burden.A maximum tolerable level of kidneyCd has been suggested as 50 μg/g (wetweight) corresponding to a urinary excretionof 2 μg Cd per day. Safe daily levels of Cdintake in humans have been recommended tobe kept below 30 μg per day.
Fire Hazard
Flammable in powder form. Combustible.
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,
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
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.
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
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.]
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.
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.
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.
Check Digit Verification of cas no
The CAS Registry Mumber 7440-43-9 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,4,4 and 0 respectively; the second part has 2 digits, 4 and 3 respectively.
Calculate Digit Verification of CAS Registry Number 7440-43:
(6*7)+(5*4)+(4*4)+(3*0)+(2*4)+(1*3)=89
89 % 10 = 9
So 7440-43-9 is a valid CAS Registry Number.
InChI:InChI=1/Cd/q+2
7440-43-9Relevant articles and documents
Synthesis and characterisation of zinc gallyl complexes: First structural elucidations of Zn-Ga bonds
Jones, Cameron,Rose, Richard P.,Stasch, Andreas
, p. 2997 - 2999 (2007)
Reactions of the anionic gallium(i) heterocycle, [:Ga{[N(Ar)C(H)] 2}]- (Ar = C6H3Pri 2-2,6), with two N,N-chelated zinc chloride complexes have yielded the compounds, [{Pri2
Synthesis, characterization and photoelectrochemical properties of poly(3,4-dioctyloxythiophene)-CdS hybrid electrodes
Refczynska, Monika,Mieczkowski, Józef,Skompska, Magdalena
, p. 2984 - 2993 (2008)
CdS-poly(3,4-dioctyloxythiophene) (CdS-PDOT) hybrid electrode has been prepared by electrosynthesis of PDOT on Au substrate followed by electrodeposition of Cd and its chemical transformation into CdS. The polymer and semiconductor obtained by this method form hemispherical structures dispersed on the substrate. The synthesized composites were characterized by UV-vis absorption spectra and energy dispersive X-ray spectra (EDS). The AFM images of the electrodes covered with different amounts of each component were correlated with photoactivity of the hybrid electrodes. Photoresponses of Au/PDOT-CdS electrodes under illumination in aqueous solution of Na2S were also compared with those of CdS without polymer. Enhancement of the photocurrent achieved for some polymer-to-semiconductor ratio is discussed in terms of the hybrid electrode morphology and hole-mediating properties of PDOT. The power conversion efficiency of the device based on CdS-PDOT hybrid electrode was determined from photocurrent-potential behavior of two electrode system, Au/CdS-PDOT/0.1 M Na2S/Pt with a variable resistance in series in the external circuit.
Synthesis of cadmium complex sulfides nanoparticles by thermal decomposition
Dumbrava,Ciupina,Jurca,Prodan,Segal,Brezeanu
, p. 399 - 405 (2005)
The paper presents the conditions of synthesis and results in the characterization (chemical analysis, thermal analysis, kinetic of decomposition) for two complex compounds of cadmium: [Cd(S2O 3)phen]×H2O and [Cd(S2/
Synthesis and thermal analysis of cadmium complexes of imidazole and its derivatives
Olczak-Kobza
, p. 129 - 134 (2001)
Mixed complexes of the type: Cd(Sal)(HIm)2, Cd(Sal)(HIm)4·H2O, Cd(Sal)(4-MHIm)4, Cd(Im)2(HIm) and Cd(Salox)(4-MHIm)2 (where Sal = OC6H4COO2-, Salox = OCsub
Electrodeposition of cadmium from a sulfate electrolyte in the presence of a fixative
Medvedev,Makrushin
, p. 62 - 64 (2010)
Electrodeposition of cadmium from a sulfate electrolyte containing CdSO4 · 8/3H2O, H2SO4, and a fixative was studied.
Synthesis, structural characterization and thermal analysis of a high nitrogen-contented cadmium (II) coordination polymer based on 1,5-diaminotetrazole
Tang, Zhan,Zhang, Jian-Guo,Liu, Zhen-Hua,Zhang, Tong-Lai,Yang, Li,Qiao, Xiao-Jing
, p. 8 - 12 (2011)
A high nitrogen-contented cadmium (II) coordination polymer [Cd(DAT) 2(N3)2]n (DAT = 1,5- diaminotetrazole) has been synthesized and characterized by elemental analysis and FT-IR spectrum. The crystal structure was determined by using single crystal X-ray diffraction analysis with monoclinic cell: P21/n space group. Each Cd(II) cation is coordinated by two trans 1,5-diaminotetrazole ligands and four trans μ-1, 3 azido bridged ligands to form an octahedral configuration. The molecule structure is novel in that two zigzag chains linked by azido ligands which are vertical to each other and thus 2D layer networks are formed. The weak hydrogen-bonds between different layers assemble the complex to 3D supramolecular structure. Under nitrogen atmosphere with a heating rate of 10 °C/min, the DSC plot of the complex shows one endothermic process and three successive exothermic processes from 50 °C to 600 °C, and the final decomposed residue at 600 °C is Cd and few condensed products.
Recovery of cadmium and change in properties of a fibrous carbon electrode in electrolytic processing of ammonia washing solutions formed in cadmium plating
Varentsova,Varentsov
, p. 241 - 247 (2007)
The possibility of recovering cadmium deposited on fibrous carbon electrodes from ammonium washing solutions formed in cadmium plating via operation of a short-circuited electrochemical system or anodic dissolution was examined. A polarization study of electrode processes that occur on a renewable graphite microelectrode in ammonium solutions of varied composition was carried out. The change in the properties of fibrous carbon electrodes in their cyclic use in electrodeposition-recovery of cadmium and the possibility of their repeated use were analyzed.
Radiation Electrochemistry of the Colloidal Cadmium Microelectrode. Catalysis of Hydrogen Formation by Organic Free Radicals
Henglein, A.,Lilie, J.
, p. 1246 - 1251 (1981)
Cadmium sols with a mean particle size of 11 nm or less were obtained in the radiolytic reduction of Cd2+ ions in the presence of 1E-4 - 1E-3 base-M sodium polyvinyl sulfate.These sols which contained small concentrations of residual Cd2+ were found to catalyze the formation of hydrogen by 1-hydroxy-1-methylethyl radicals, (CH3)2COH, as efficiently as the sols of the previously studied noble metals.The organic radicals transfer electrons to the colloidal particles at a practically diffusion-controlled rate.The cathodically charged colloidal particles first reduce and deposit residual cadmium ions and then store excess electrons.Both the stored electrons and the deposited cadmium atoms are able to produce H2 from water.The reduction of water by deposited cadmium atoms is explained by a two-step mechanism: (1) dissolution of an atom as Cd2+ to leave negative charges on the colloidal particle and (2) transfer of these charges to water.The mechanism of catalysis is also described in terms of an equivalent electrical circuit, in which the colloidal microelectrode appears as a capacitance for the storage of reduction equivalents.A 3E-4 M cadmium solution (containing ca. 3E-5 M residual Cd2+ ions) was found to have a capacity of 0.98 F/L for the storage of excess electrons.
Simple thermal evaporation route to synthesize Zn and Cd metal nanowires
Kar, Soumitra,Ghoshal, Tandra,Chaudhuri, Subhadra
, p. 174 - 178 (2006)
Metallic Zn and Cd nanowires were produced by a simple thermal evaporation process using their respective sulfide powders as the precursors. Metallic nanowires were found to be of pure phase without the presence of any sulfide or oxide phases. These nanowires were single crystalline. Diameters of both the Zn and Cd nanowires varied within 100-150 nm and their lengths were approximately a few micrometers. Crystal structure, phase and chemical purity of the nanowires were characterized by XRD and EDAX. The morphology and crystallinity of the products were revealed by SEM and TEM studies.
Synthesis, structural characterization, and spectroscopy of the cadmium-cadmium bonded molecular species Ar′CdCdAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-Pr i2)2)
Zhu, Zhongliang,Fischer, Roland C.,Fettinger, James C.,Rivard, Eric,Brynda, Marcin,Power, Philip P.
, p. 15068 - 15069 (2006)
The synthesis and first structural characterization of a cadmium-cadmium bonded molecular compound Ar-CdCdAr- (Ar- = C6H3-2,6-(C6H3-2,6-Pri2)2) are reported. The existence of the Cd-Cd bond was established by 113Cd NMR spectroscopy and X-ray diffraction (Cd-Cd = 2.6257(5) A). Like its group 12 analogue Ar-ZnZnAr-, DFT calculations showed that Ar-CdCdAr- had significant p-character in the Cd-Cd σ-bonding HOMO. Copyright
![6Hg(2+)*4As(2-)*CdBr6(4-)=[Hg6As4][CdBr6]](http://file1.lookchem.com/cas/reactions/2021/08/20/16684518.svg+xml_ms)
![6Hg(2+)*4Sb(2-)*CdI6(4-)*0.6Hg=[Hg6Sb4][CdI6]Hg0.6](http://file1.lookchem.com/cas/reactions/2021/08/20/18017943.svg+xml_ms)
2]](http://file1.lookchem.com/cas/reactions/2021/08/20/18147823.svg+xml_ms)
![[Cd(C5H3N(C(CH3)NC6H4NSO2C6H4CH3)2)(H2O)]*H2O](http://file1.lookchem.com/cas/reactions/2021/08/20/17764806.svg+xml_ms)
