Cadmium A chemical element, chemical symbol Cd, atomic number 48, atomic weight 112.411, belonging to the periodic system IIB. In 1817, F. Strommel of Germany discovered cadmium from zinc carbonate. KSL Herman and JCH Rolf also found cadmium in zinc oxide. The English name is derived from Latin cadmia, which means rivite. Cadmium content in the crust of 2 × 10-5%, are present as compounds in nature, mainly mineral ore cadmium sulfur (CdS), zinc and lead zinc, copper, lead-zinc symbiosis, flotation Most of the time it enters the zinc concentrate and is enriched in the soot during the roasting process. In wet zinc smelting, cadmium is present in the copper cadmium slag. Cadmium is a silver-white metallic luster, melting point 320.9 deg.] C, a boiling point of 765 deg.] C, a relative density of 8.642. Resilience and ductility. Cadmium slowly oxidizes in humid air and loses its metallic luster, which forms a brown oxide layer on heating. At high temperatures, cadmium reacts strongly with halogen to form cadmium halide. It can also be directly combined with sulfur to form cadmium sulfide. Cadmium is soluble in acid but insoluble in alkali. The oxidation state of cadmium is +1, +2. Cadmium oxide and cadmium hydroxide have very low solubility, they are soluble in acid, but insoluble in alkali. Cadmium can form a variety of complex ions, such as Cd (NH3), Cd (CN), CdCl and the like. Cadmium is highly toxic, and air and food contaminated with cadmium are seriously harmful to humans. In Japan, cadmium poisoning has been "painful."
Metal cadmium can be obtained from cadmium-containing soot or cadmium slag (such as coal or carbon reduction or sulfuric acid leaching and zinc powder replacement) in a variety of ways. Further purification can be carried out by electrolytic refining and vacuum distillation. Cadmium is mainly used for electroplating of steel, iron , copper, brass and other metals, and has strong corrosion resistance to alkaline substances. Cadmium can be used to make batteries that are small in size and large in capacity. Cadmium compounds are also used in large quantities for the production of pigments and phosphors. Cadmium sulfide, cadmium selenide, and cadmium telluride are used in the manufacture of photovoltaic cells.
Cadmium poisoning
The toxic effects produced by cadmium and its compounds entering the body through food, water and air. There are acute and chronic poisoning points. Inhalation of large amounts of cadmium oxide fumes in industrial production can cause acute poisoning. Early manifestations include sore throat, cough, chest tightness, shortness of breath, dizziness, nausea, body aches, weakness, fever, etc. In severe cases, toxic pulmonary edema or chemical pneumonia may occur. The poisoned person has high difficulty in breathing, and a large amount of foamy bloody sputum. Life-threatening due to acute respiratory failure. Use cadmium-plated utensils to prepare or store acidic foods or beverages. Foods and beverages may contain cadmium, which can cause poisoning after eating. The incubation period is short, usually after 10 to 20 minutes, gastrointestinal symptoms such as nausea, vomiting, abdominal pain, and diarrhea can occur. In severe cases, there may be dizziness, sweating, prostration, numbness of the limbs, and convulsions. Long-term exposure to cadmium and its compounds can cause chronic poisoning and cause kidney damage. The main manifestation is that the urine contains a lot of low molecular weight proteins. Although the glomerular filtration function is normal, the renal tubular absorption function is reduced, and urinary cadmium is reduced. The discharge increases.
Inhalation of acute poisoning caused by oxidized cadmium, the key to treatment is to prevent pulmonary edema. Early evacuation of toxic sites, bed rest, oxygen, keep the airway open, inhalation of antifoam (dimethicone) to eliminate foam; adrenal cortex hormones can reduce capillary permeability, should be used in early enough; limit liquid intake amount, given antibiotics to prevent secondary infection; acute cadmium poisoning ingestion mainly symptomatic treatment; administering a lot of fluid, atropine is used antiemetic and eliminate pain; chronic cadmium intoxication renal impairment, dietary calcium and phosphorous acid should be added Salt intake, supplying sufficient zinc and protein.
Cadmium poisoning can deform the intramuscular atrophy joint, bone pain is unbearable, can not fall asleep, pathological fracture, resulting in death. The main source of cadmium is the cadmium-containing wastewater discharged from the factory into the riverbed, irrigated rice fields, absorbed by plants and accumulated in rice. If long-term consumption of cadmium-containing rice, or drinking cadmium-containing sewage, it is easy to cause "bone pain."
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