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Selenium Suppliers list
Company Name: Henan DaKen Chemical CO.,LTD.
Tel: +86-371-55531817
Products Intro: Product Name:Selenium
Purity:99% Package:100g,500g,1kg,5kg,10kg
Company Name: Henan Tianfu Chemical Co.,Ltd.
Tel: 0371-55170693
Products Intro: CAS:7782-49-2
Purity:99% Package:500G;1KG;5KG;25KG
Company Name: Mainchem Co., Ltd.
Tel: +86-0592-6210733
Products Intro: Product Name:Selenium
Company Name: career henan chemical co
Tel: +86-371-86658258
Products Intro: Product Name:Selenium
Purity:98% Package:1KG;1000USD
Company Name: Changsha Halin Chemical Technology Co., Ltd.  Gold
Tel: 18229709969,13787155389
Products Intro: Product Name:SeleniuM
Purity:99.99% Package:10g--1kg--5kg--25kg--1000kg

Lastest Price from Selenium manufacturers

  • Selenium
  • US $1000.00 / KG
  • 2018-07-27
  • CAS:7782-49-2
  • Min. Order: 25KG
  • Purity: 98%
  • Supply Ability: 10tons
Selenium Basic information
Introduction Physical Properties Application Production Reactions Toxicity
Product Name:Selenium
Product Categories:metal or element;Inorganics;Pure ElementsChemical Synthesis;SeleniumMetal and Ceramic Science;Catalysis and Inorganic Chemistry;Electronic Chemicals;Micro/Nanoelectronics;Metal and Ceramic Science;Metals;Selenium
Mol File:7782-49-2.mol
Selenium Structure
Selenium Chemical Properties
Melting point 217 °C(lit.)
Boiling point 684.9 °C(lit.)
density 4.81 g/mL at 25 °C(lit.)
vapor pressure <1 Pa (20 °C)
storage temp. Storage temperature: no restrictions.
solubility H2O: soluble
form powder
color White to creamy white
resistivity1.2 μΩ-cm, 0°C
Water Solubility Insoluble
Merck 13,8505
Stability:Stable. Incompatible with strong acids, strong oxidizing agents and most common metals. Combustible.
CAS DataBase Reference7782-49-2(CAS DataBase Reference)
NIST Chemistry ReferenceSelenium atom(7782-49-2)
EPA Substance Registry SystemSelenium(7782-49-2)
Safety Information
Hazard Codes T
Risk Statements 36/38-53-33-23/25
Safety Statements 26-61-45-28-20/21-28A
RIDADR UN 3440 6.1/PG 3
WGK Germany 2
RTECS VS7700000
HazardClass 9
PackingGroup III
HS Code 28049090
Hazardous Substances Data7782-49-2(Hazardous Substances Data)
ToxicityLD50 orally in Rabbit: 6700 mg/kg
MSDS Information
SigmaAldrich English
ACROS English
ALFA English
Selenium Usage And Synthesis
IntroductionSelenium was discovered by Berzelius and Gahn in1817 while investigating the lead chamber process for making sulfuric acid. They initially believed that the bottom of the lead chamber generating an offensive odor was due to presence of tellurium, a sulfur group element that was discovered thirty-five years earlier. Further studies indicated a new element, the chemical properties of which were very similar to tellurium. This new element was named selenium, derived from the Greek word selene, meaning moon. The name followed tellus, the Latin word for earth given to tellurium which chemically resembled the new element. Willoughby Smith in 1873 discovered photoresistivity in this metal; i.e., as the intensity of light exposure on the metal increased, its current resistance decreased.
Selenium is a very rare element. The metal does not occur in nature in free elemental form. Its abundance in the earth’s crust is about 0.05 mg/kg. It occurs in certain copper ores and sometimes with native sulfur. Some selenium containing minerals are eucairite, CuAgSe; clausthalite, PbSe; naumannite, Ag2Se; crookesite, (CuTlAg)2Se; and zorgite, PbCuSe.
Physical PropertiesSelenium exists in several allotropic forms. Three distinct forms are (1)amorphous (2)crystalline and (3)metallic:
Amorphous forms exhibit two colors, occurring as a red powder of density 4.26g/cm3 that has a hexagonal crystal structure and a black vitreous solid of density 4.28g/cm3. The red amorphous selenium converts to the black form on standing. Amorphous selenium melts at 60 to 80°C; insoluble in water; reacts with water at 50°C when freshly precipitated; soluble in sulfuric acid, benzene and carbon disulfide.
Crystalline selenium exhibits two monoclinic forms: an alpha form constituting dark red transparent crystals, density 4.50 g/cm3. The alpha form converts to a metastable beta form of hexagonal crystal structure when heated to about 170°C. Both the crystalline forms are insoluble in water; soluble in sulfuric and nitric acids; very slightly soluble in carbon disulfide. Also, both the crystalline forms convert into gray metallic modification on heating.
The gray metallic form of selenium is its most stable modification. It constitutes lustrous gray to black hexagonal crystals; density 4.18 g/cm3 at 20°; melts at 217°C; soluble in sulfuric acid and chloroform; very slightly soluble in carbon disulfide; insoluble in alcohol.
All forms of selenium vaporize at 684.8°C.
ApplicationSelenium has many industrial uses, particularly electronic and solid-state applications, which have increased phenomenally in recent years. This is attributed to its unique properties: (1) it converts light directly to electricity (photovoltaic action); (2) its electrical resistance decreases with increased illumination (photoconductivity); and (3) it is able to convert alternating current to direct current.
Selenium is used in photoelectric cells, solar cells, and as a rectifier in radio and television sets. It also was used historically in exposure meters in photography and as an ingredient of toning baths. It is used in photocopying documents. In the glass industry it is incorporated to pigments to color pink, orange, and ruby-red glass. Other applications are as a metallic base in preparing electrodes for arc light; as an additive to stainless steel; in chrome plating bath for inducing microcracks for corrosion control; in vulcanization of rubber; as a catalyst; and as a flame-proofing agent for electric switchboard cables.
Although a toxic metal, selenium in trace amounts is a nutritional element. Trace amounts added to cattle food are effective against muscular dystrophy in sheep and cattle.
ProductionSelenium is recovered from anode muds or slimes in electrolytic refining of copper. Anode mud is treated with sulfuric acid and roasted. Selenium is converted to its dioxide, which vaporizes and is collected in a wet scrubber system.
Alternatively, raw anode slimes are aerated with hot dilute sulfuric acid to remove copper. Slimes are then mixed thoroughly with sodium carbonate and roasted in the presence of sufficient air. Sodium selenate formed is leached with water. Hydrochloric acid is added to this selenate solution. Treatment with sulfur dioxide precipitates elemental selenium. Alternatively, the selenate solution is evaporated to dryness. Sodium selenate is reduced to sodium selenide by heating with carbon at high temperatures. Sodium selenide is leached with water. Air is blown over the solution. Selenide is oxidized to elemental selenium which precipitates.
In another process known as soda-niter smelting, a slight variation of the above method, after removal of copper anode slimes are mixed with sodium carbonate and silica and charged to the furnace. First, slags are removed. To the molten mass, caustic soda and potassium nitrate are added. Selenium and tellurium separate into the slags. The slags are cooled, crushed, and leached with water. Sulfuric acid is added. This precipitates tellurium as dioxide. Sulfur dioxide is then passed through the solution precipitating elemental selenium.
Selenium obtained by the above methods is about 99% pure. High purity metal may be obtained by refining this commercial grade material. Commercial grade selenium is distilled to form highly purified metal. Another refining method involves melting the crude metal and bubbling hydrogen through it. Hydrogen selenide so formed is decomposed at 1,000°C. A third method involves oxidizing selenium to its dioxide and reducing the latter with ammonia at 600 to 800°C.
Selenium was recovered earlier from flue dusts from lead and copper sulfide ores. This process is now obsolete and no longer used.
ReactionsThe chemical properties of selenium fall between sulfur and tellurium. Thus, selenium reacts with oxygen similarly to sulfur, forming two oxides, selenium dioxide, SeO2 and trioxide, SeO3. The metal combines with halogens forming their halides. With nonmetals, selenium forms binary compounds exhibiting oxidation states +4 and +6.
Selenium reacts with electropositive metals and hydrogen forming selenides, where its oxidation state is –2. Thus, it combines with sodium to form sodium selenide, Na2Se. When the metal is heated with hydrogen below 250°C, the product is hydrogen selenide, H2Se.
The metal is not attacked by hydrochloric acid, nor does it react with dilute nitric and sulfuric acids. High purity selenium reacts slowly with concentrated nitric acid. The crude metal, however, dissolves in cold concentrated nitric acid.
When fused with caustic soda or caustic potash, sodium selenate, or potassium selenate, Na2SeO4, or K2SeO4 is obtained.
Molten selenium combines with most metals forming selenides. Such metal selenides include Ag2Se, Cu2Se, HgSe, ZnSe, CdSe, PbSe, FeSe, FeSe2, and Sb2Se3.
Selenium dissolves in sulfur and tellurium in all proportions.
ToxicityAlthough an essential nutrient metal at trace concentrations, selenium is highly toxic at moderate concentrations. Some of its compounds, such as hydrogen selenide, are very toxic. Exposure to Se metal fumes can cause severe irritation of eyes, nose and throat. The metal is listed by the US EPA as one of the priority pollutant metals in the environment.
Chemical PropertiesSelenium exists in three forms: a red amor- phous powder, a gray form, and red crystals. Occurs as an impurity in most sulfide ores. Selenium, along with tellu- rium, is found in the sludges and sediments from electro- lytic copper refining. It may also be recovered in flue dust from burning pyrites in sulfuric acid manufacture.
Chemical Propertiesdark grey to dark red powder or crystals
Chemical PropertiesJewelers most frequently encounter selenium in the form of brass-black and gun-bluing compounds. Selenium print toner used by photographers is sometimes used by jewelers as a metal-coloring solution. These coloring mixtures usually contain selenic acid. Selenic acid can release hydrogen selenide gas that can cause illness, and used daily, it might enlarge the liver and spleen. Tellurium is sometimes used in association with selenium.
HistoryDiscovered by Berzelius in 1817, who found it associated with tellurium, named for the Earth. Selenium is found in a few rare minerals, such as crooksite and clausthalite. In years past it has been obtained from flue dusts remaining from processing copper sulfide ores, but the anode muds from electrolytic copper refineries now provide the source of most of the world’s selenium. Selenium is recovered by roasting the muds with soda or sulfuric acid, or by smelting them with soda and niter. Selenium exists in several allotropic forms. Three are generally recognized, but as many as six have been claimed. Selenium can be prepared with either an amorphous or crystalline structure. The color of amorphous selenium is either red, in powder form, or black, in vitreous form. Crystalline monoclinic selenium is a deep red; crystalline hexagonal selenium, the most stable variety, is a metallic gray. Natural selenium contains six stable isotopes. Twentynine other isotopes and isomers have been characterized. The element is a member of the sulfur family and resembles sulfur both in its various forms and in its compounds. Selenium exhibits both photovoltaic action, where light is converted directly into electricity, and photoconductive action, where the electrical resistance decreases with increased illumination. These properties make selenium useful in the production of photocells and exposure meters for photographic use, as well as solar cells. Selenium is also able to convert a.c. electricity to d.c., and is extensively used in rectifiers. Below its melting point, selenium is a p-type semiconductor and is finding many uses in electronic and solid-state applications. It is used in xerography for reproducing and copying documents, letters, etc., but recently its use in this application has been decreasing in favor of certain organic compounds. It is used by the glass industry to decolorize glass and to make rubycolored glasses and enamels. It is also used as a photographic toner, and as an additive to stainless steel. Elemental selenium has been said to be practically nontoxic and is considered to be an essential trace element; however, hydrogen selenide and other selenium compounds are extremely toxic, and resemble arsenic in their physiological reactions. Hydrogen selenide in a concentration of 1.5 ppm is intolerable to man. Selenium occurs in some soils in amounts sufficient to produce serious effects on animals feeding on plants, such as locoweed, grown in such soils. Selenium (99.5%) is priced at about $250/kg. It is also available in high-purity form at a cost of about $350/kg (99.999%).
Usesselenium is a trace mineral used for years in topical preparations for its anti-fungal properties. Selenium has been shown to have other protective effects such as repairing DnA, reducing the DnA-binding of carcinogens, and suppressing gene mutations. In laboratory studies, skin lotions containing selenium compounds have been shown to decrease uV-induced skin damage such as inflammation, blistering, and pigmentation.
General DescriptionSelenium is a reddish colored powder that may become black upon exposure to air. Selenium is toxic by ingestion. Selenium is used to manufacture electronic components and rubber.
Air & Water ReactionsInsoluble in water.
Reactivity ProfileSELENIUM, silicon, or sulfur ignites in fluorine gas at ordinary temperatures [Mellor 2:11-13 1946-47]. A mixture of barium carbide and selenium heated to 150° C becomes incandescence [Mellor 5:862 1946-47]. Calcium carbide and selenium vapor react with incandescence [Mellor 5:862 1946-47]. A moist mixture of selenium and chlorates, except the alkali chlorates, becomes incandescent. Selenium reacts violently with chromium trioxide [Mellor 11:233 1946-47]. Reaction of selenium and silver bromate (also potassium bromate) is violently explosive [Mellor 2, Supp1:763 1956]. Freshly reduced selenium reacts vigorously with nitric acid. Trace amounts of organic matter probably influenced the reaction [J. Chem. Soc. 1938 p.391]. The reaction between zinc and selenium or tellurium is accompanied by incandescence [Mellor 4:476-480 1946-47].
Health HazardHighly toxic, may be fatal if inhaled, swallowed or absorbed through skin. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
Health HazardExposures to selenium cause adverse health effects. selenium dioxide is a by-product of copper and nickel melting, or of heating alloys containing selenium. The dusts are very irritating to the mucous membranes and the lungs. Contact can cause dermatitis.
Fire HazardCombustible material: may burn but does not ignite readily. Containers may explode when heated. Runoff may pollute waterways. Substance may be transported in a molten form.
Safety ProfilePoison by intravenous route. When heated to decomposition it emits toxic fumes of Se. See also SELENIUM and SELENIUM COMPOUNDS
Potential ExposureMost of the selenium produced is used in the manufacture of selenium rectifiers. It is also utilized as a pigment for ruby glass, paints, and dyes; as a vulcaniz- ing agent for rubber; a decolorizing agent for green glass; a chemical catalyst in the Kjeldahl test; as an insecticide; in the manufacture of electrodes, selenium photocells, sele- nium cells, and semiconductor fusion mixtures; in photo- graphic toning bathes; and for dehydrogenation of organic compounds. It is also used in veterinary medicine and in antidandruff shampoos. Se is used in radioactive scanning for the pancreas and for photostatic and X-ray xerography. It may be alloyed with stainless steel; copper, and cast steel. Selenium is a contaminant in most sulfide ores of copper, gold, nickel, and silver; and exposure may occur while removing selenium from these ores.
First aidIf this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, includ- ing resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medi- cal attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pneumonitis or pulmonary edema, a doctor or authorized paramedic may consider administer- ing a drug or other inhalation therapy.
ShippingUN3283 Selenium compound, solid, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous material, Technical Name Required.
Purification MethodsDissolve selenium in small portions in hot conc HNO3 (2mL/g), filter and evaporate to dryness to give selenious acid which is then dissolved in conc HCl. Pass SO2 gas through the solution whereby selenium (but not tellurium) precipitates. It is filtered off and washed with conc HCl. This purification process is repeated. The selenium is then converted twice to the selenocyanate by treating with a 10% excess of 3M aqueous KCN (CARE), heated for half an hour on a sand-bath and filtered. Add an equal weight of crushed ice to the cold solution, followed by an excess of cold, conc HCl, with stirring (in an efficient fume cupboard as HCN is evolved) which precipitates selenium powder. This is washed with water until colourless, and then with MeOH and is heated in an oven at 105o. Finally it is fused for 2hours in vacuo. It is cooled, crushed and stored in a desiccator [Tideswell & McCullough J Am Chem Soc 78 3036 1956].
IncompatibilitiesReacts violently with strong acids and strong oxidizers, chromium trioxide; potassium bromate;cadmium. Reacts with incandescence on gentle heating with phosphorous and metals, such as nickel, zinc, sodium, potassium, platinum. Reacts with water @ 50 ? C forming flammable hydrogen and selenious acids.
Waste DisposalPowdered selenium: dispose in a chemical waste landfill. When possible, recover selenium and return to suppliers
PrecautionsDuring use and handling of selenium, occupational workers should be careful to avoid contact with the skin. Selenium compounds are considered very damaging to the liver, and hazardous.
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