The vast majority of nickel is used in alloys and more than 3,000 nickel alloys have been identified. Nickel is used to make stainless steel and other metal alloys. Nickel is commonly alloyed with iron, copper (Monel), chromium, aluminium and zinc. Alloys are used in the making of metal coins and jewellery and, in industry, for making metal items. Nickel and nickel compounds are used for nickel electroplating, to colour ceramics, to make batteries, for permanent magnet materials, and as catalysts.
Nickel acetate is used mainly as a mordant in the textile industry, and as a hydrogenation catalyst. It is also used as an intermediate in the formation of other nickel compounds, as a sealer for anodised aluminium, and in nickel electroplating.
Nickel carbonate is used as a chemical intermediate for nickel oxide, nickel powder, and nickel catalysts. It serves in electric components, such as vacuum tubes and transistor cans. It is used as a catalyst to remove organic contaminants from wastewater or potable water. It is used in the preparation of coloured glass, in the manufacture of certain nickel pigments, as a neutralising compound in nickel electroplating solution, and in the preparation of many specialty nickel compounds.
Nickel hydroxide is used in nickel-cadmium batteries and as a chemical intermediary for nickel catalysts and nickel salts. The hydrogenation of finely powdered newspaper with a nickel hydroxide catalyst produces conversion in high yields of cellulose feed materials to liquid hydrocarbon fuels.
Nickel oxide is used in fuel cell electrodes, the production of active nickel catalysts, electroplating, and colouring and decolourising glass. It is also used in the manufacture of nickel salts which can be used to make refined nickel oxide. It is used in non-metallic resistance thermometers or thermistors, which are temperature-sensitive semiconducting ceramics.
Substance name: Nickel and compounds
CASR number: 7440-02-0
Molecular formula: Ni
Synonyms: Raney alloy, Raney nickel, C.I. 77775.
Nickel compounds covered by this article include nickel acetate (CASR# 373-02-4), nickel carbonate (CASR# 3333-67-3), nickel chloride (CASR# 7718-54-9), nickel hydroxide (CAS #12054-48-7), nickel nitrate (CASR# 13138-45-9), nickel oxide (CAS #1313-99-1), and nickel sulfate (CASR# 7786-81-4). Nickel carbonyl and nickel subsulfide are treated separately in the NPI.
Nickel is a silvery-white, hard, malleable, ductile, ferromagnetic metal. It is a good conductor of electricity and heat.
Atomic Number: 28
Atomic Mass: 58.7
Melting Point: 1453°C
Boiling Point: 2732°C
Specific Gravity: 8.9
Properties vary widely depending on the particular compound. Some physical properties for selected nickel compounds follow.
Nickel acetate is a green powder that effloresces somewhat in air. It has a light acetic acid odour.
Nickel carbonate occurs as light green rhombic crystals or as a brown powder. It decomposes before it melts.
Nickel hydroxide occurs as either a fine green powder, green crystals, or an amorphous black powder. Its melting point is 230°C and its vapour density is 3.2.
Nickel oxide occurs as a green or black powder that becomes yellow when heated. Nickel oxide has a specific gravity of 6.7 and melts at 1960°C.
Nickel sulfate is a yellow-green crystalline solid. It decomposes when heated. Its specific gravity is 3.7.
Nickel metal is relatively resistant to corrosion. It dissolves in dilute mineral acids and is insoluble in concentrated nitric acid.
Water solubility of nickel compounds vary. Nickel acetate, bromide, chloride, iodide, nitrate and sulfate are soluble in water. Hydrated nickel (II) is the primary ion in aqueous solutions. Nickel oxides, hydroxides, sulfides, arsenide, chromate, carbonate, phosphate and selenide are water-insoluble nickel compounds. More properties for selected nickel compounds follow.
Nickel oxide is soluble in acids, potassium cyanide, and ammonium hydroxide. It is insoluble in both cold and hot water, and caustic solutions. The black form of nickel oxide is chemically reactive, whereas the green nickel oxide form is inert and refractory.
Nickel acetate is soluble in acetic acid and water, and insoluble in alcohol. Nickel acetate decomposes before it melts, forming nickel oxide and emitting irritating fumes.
Nickel carbonate is soluble in dilute acids and ammonia, and insoluble in hot water. It can react violently with iodine, hydrogen sulfide, or a mixture of barium oxide and air.
Nickel hydroxide is soluble in acids and ammonium hydroxide, but is practically insoluble in water. It decomposes into nickel oxide and water when heated at elevated temperatures.
The National Pollutant Inventory (NPI) holds data for all sources of nickel and compounds emissions in Australia.
This depends on how much nickel a person has been exposed to, for how long, the nature of the nickel compound(s), and current state of health. A small amount of nickel is probably essential for humans, although a lack of nickel has not been found to the health of humans. An allergic skin reaction is the most common adverse health effect in people who are sensitive to nickel. People can become sensitive to nickel when jewellery or other products containing nickel are in direct contact with the skin. Once a person is sensitised to nickel, further contact with nickel will produce a reaction, most commonly a skin rash at the site of contact (dermatitis). Less frequently, some sensitised persons may have asthma attacks following exposure to nickel. Some people may react when they eat nickel in food, drink it in water, or breathe dust containing it. People who are not sensitive to nickel must eat very large amounts of nickel to show adverse health effects.
Exposure to nickel salts can cause 'nickel itch', which causes burning and itching sensations in the hands, followed by abnormal redness of the skin and nodular eruption on the web of fingers, wrists and forearms. Nickel salts act as emetics when swallowed. Workers who accidentally drank water containing very high levels of nickel (100,000 times more than in normal drinking water) had stomach aches, and blood and kidney disorders. Nickel dust is irritating to the eyes, nose and throat. Lung effects, including chronic bronchitis, reduced lung function, and lung cancer, as well as nasal effects, including rhinitis, nasal sinusitis, nasal mucosal injury and sinus cancer, have been observed in workers who breathed high levels of nickel while working in nickel refineries or nickel processing plants. Nickel platers exposed to nickel sulfate and welders exposed to nickel oxides have been linked with asthma. Evidence for the carcinogenicity of nickel metal and other compounds is relatively weak or inconclusive, but insoluble dusts of nickel oxides, and soluble aerosols of nickel sulfate, nitrate, and chloride, have been implicated as potential carcinogens.
Entering the body
Nickel and compounds can be inhaled or ingested.
Major sources of exposure for most people are by eating food and drinking water which contain natural amounts of nickel. Breathing cigarette smoke or smoking tobacco is another way of being exposed to nickel. Skin contact with nickel can occur when handling coins, touching other nickel containing metals, or wearing nickel jewellery. Elevated levels of nickel may be encountered near industries using nickel and/or nickel compounds. Occupational exposure can occur in industries using nickel in various forms.
Workplace exposure standards
Safe Work Australia sets the workplace exposure standards for lead and compounds through the workplace exposure standards for airborne contaminants. These standards are only appropriate for use in workplaces and are not limited to any specific industry or operation. Make sure you understand how to interpret the standards before you use them.
- Maximum eight hour time weighted average (TWA): 1 mg/m3
- Maximum eight hour time weighted average (TWA): 1 mg/m3
- Maximum eight hour time weighted average (TWA): 0.1 mg/m3
Drinking water guidelines
The Australian Drinking Water Guidelines include the following guidelines for acceptable water quality:
- Maximum of 0.02 milligrams per litre of water for health purposes
Very small amounts of nickel have been shown to be essential for normal growth and reproduction in some species of animals. Nickel and its compounds can have high acute and chronic toxicity to aquatic life. Nickel toxicity to aquatic organisms is determined by water hardness - the softer the water, the higher the toxicity. Insufficient data are available to evaluate or predict the short term and the long term effects of nickel and its compounds to plants, birds, or land animals. Nickel does not appear to collect in fish, plants, or animals used for food.
Entering the environment
Nickel can be transported as particles released into the atmosphere or as dissolved compounds in natural waters.
Where it ends up
Finely divided particles of nickel and nickel compounds are mainly carried by air. Contributions to the atmosphere come from both natural sources and human activity, with input from both stationary and mobile sources. Various dry and wet precipitation processes remove particulate matter as wash out or fallout from the atmosphere with transfer to soils and waters. Soil borne nickel may enter waters by surface run off or by percolation into ground water.
Nickel occurs naturally in surface waters from the weathering of minerals and rocks. Once nickel is in surface and ground water systems, physical and chemical interactions (complexation, precipitation/dissolution, adsorption/desorption, and oxidation/reduction) will determine its fate. Under normal conditions, nickel is overwhelmingly associated with abundant iron and manganese particles which precipitate and absorb free nickel ions. Much of the nickel in the environment is therefore found in soils and sediments. Organic material in polluted environments will keep nickel soluble.
Australian Water Quality Guidelines for Fresh and Marine Waters: (ANZECC, 1992):
Maximum of 0.015 milligram/L (i.e. 0.000015 g/L) to 0.15 milligram/L (i.e. 0.00015 g/L) in fresh waters (depending on water hardness) and 0.015 milligram/L (i.e. 0.000015 g/L) in marine waters respectively.
Combustion of coal and other fossil fuels leads to release of nickel to the atmosphere. Other sources of atmospheric nickel include emissions from mining and refining operations, steel production, nickel alloy production, electroplating, and municipal waste incineration. Sources of nickel in water and soil include wastewater from municipal sewage treatment plants. Nickel oxide has been identified in residual fuel oil and in atmospheric emissions from nickel refineries.
Diffuse sources, and industry sources included in diffuse emissions data
A minor source of atmospheric nickel is windblown dust. Sources of nickel in water and soil include stormwater run off, soil contaminated with municipal sewage sludge, and ground water near landfill sites.
Nickel is an abundant element. It is naturally found in soils, waters, and foods, and is emitted from volcanoes. It mainly occurs in combination with arsenic, antimony and sulfur in the environment. A large resource of nickel lies in the seabed. Pure nickel is found alloyed with iron in many meteors and the earth's core is believed to contain substantial quantities. Commercially important nickel ores are garnierite, pyrrhotite and millerite.
Vehicles running on petrol and diesel fuel can contribute to nickel emissions to the atmosphere.
Coins, jewellery, nickel-cadmium batteries, some paints and ceramics, magnetic tapes, computer components, goods containing stainless steel (sinks, cooking utensils, cutlery).
Sources used in preparing this information
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