| Identification | More | [Name]
Manganese | [CAS]
7439-96-5 | [Synonyms]
Dienol
Mangan
cutaval
Magnacat
MN000200
MN000150
MN000160
MN000301
MN000300
MN000110
MN000130
MN000170
MN007905
MN000050
MN000180
MN000120
MN000080
MN007920
MN000190
MN000070
MN000090
MN000140
MN000060
MN007910
MN000100
Tronamang
ASTM A601
MANGANESE
MN STANDARD
TRONAMANG(R)
Manganese-55
manganese(0)
MANGANESEFUME
MANGANESEDUST
manganese atom
mangan(polish)
Manganese chips
ManganesechipsN
Manganese, 99+%
MANGANESE METAL
Manganese, flake
Manganese pieces
Manganese powder
Manganese, 99.5%
Manganes Solution
mangannitridovany
Manganes standard
Manganese ,99.99%
Manganese granules
colloidalmanganese
Mangan nitridovany
manganese，metallic
MANGANESE STANDARD
Manganesepowdermesh
Colloidal manganese
High pure Manganese
manganeseelementaire
manganesemonohydride
ManganesepowderNmesh
Manganese respirable
MANGANESE, FLAKE, 99.
MANGANESE AA STANDARD
MANGANESE(II) NITRATE
GOLD 1,000PPM FOR ICP
GOLD 10,000PPM FOR ICP
Manganese(Metal)Flakes
MetallicManganeseFlake
MANGANESE ICP STANDARD
MANGANESE ELECTROLYTIC
Manganese powder,(99%)
MANGANESE METAL POWDER
Electrolytic manganese
Manganesepowder(99.5%)
MANGANESE METAL, 99.98%
MANGANESE: 99.99%, LUMP
Manganese chips (99.9%)
Tripart liquid manganese
ManganesePowder(Lab)99.8%
manganesecompoundsandfume
MANGANESE, POWDER, 99.99%
MANGANESE POWDER 99+ 250 G
MANGANESE ICP/DCP STANDARD
Electrolyticmanganesemetal
MANGANESE CHIPS: 99.9%, 3N
Manganese, Powder 325 Mesh
Manganese(Metal)Powder(Lab)
Manganese Rod/Φ3x50mm/99.8%
Manganese Rod/Φ6x50mm/99.8%
GERMANIUM 10,000PPM FOR ICP
MANGANESE STANDARD SOLUTION
Manganese solution 1000 ppm
MANGANESE SCALES EXTRA PURE
MANGANESE ELECTROLYTIC 99.9%
Manganese, Pieces, Irregular
Manganese standard for AAS
Manganese ISO 9001：2015 REACH
Manganese standard for ICP
Manganese solution 10 000 ppm
MANGANESE, ANALYTICAL STANDARD
manganesecompoundsandfume(asmn)
Manganese Fumes (also see metal)
Manganese,99+%,powder, -325 mesh
MANGANESE, AAS STANDARD SOLUTION
Manganese Electronic Metal Flake
Manganese Sheet/1x10x10mm/99.95%
Manganese Sheet/1x25x25mm/99.95%
Manganese Sheet/2x10x10mm/99.95%
Manganese Sheet/2x25x25mm/99.95%
manganese coating quality balzers
MANGANESE SINGLE ELEMENT STANDARD
Electrolyticalgrademanganesechips
Manganese, Powder 325 Mesh 99.95%
Manganese, 99+%, powder, -40 Mesh
MANGANESE PLASMA EMISSION STANDARD
MANGANESE, POWDER, -325 MESH, 99+%
MANGANESE, POWDER, -50 MESH, 99.9%
MANGANESE METALLO-ORGANIC STANDARD
MANGANESE, CHIP, <1.5MM THICK, 99%
MANGANESE, POWDER, SYNTHESIS GRADE
MANGANESE, PLASMA STANDARD SOLUTION
Manganese, Pieces, Irregular 99.99%
Manganese and its compounds (as Mn)
MANGANESE AA SINGLE ELEMENT STANDARD
MANGANESE ATOMIC ABSORPTION STANDARD
Manganese, powder, 50-325 mesh, 99+%
Manganese Metal, 50-325 Mesh, Powder
Manganese standard for water analysis
MANGANESE, CHIP, <1.5MM THICK, 99.98%
MANGANESE ATOMIC SPECTROSCOPY STANDARD
Manganese AA Standard,1000 ppm in HNO3
MANGANESE, OIL BASED STANDARD SOLUTION
INDOL ORNITINE MOTILITY MEDIUM 120X9ML
Tronamang electrolytic manganese metal
MANGANESE, POWDER, 99.99% METALS BASIS
Manganese, 99+%, powder, -40 Mesh 250GR
MANGANESE ICP STANDARD TRACEABLE TO SRM
MANGANESE STANDARD 1000 MG MN (MNCL2 IN
MANGANESE STANDARD SOLUTION TRACEABLE TO
MANGANESE SINGLE ELEMENT PLASMA STANDARD
MANGANESE FLAKES SMALLER THAN 4 MM 99.8%
Manganese pieces, 10mm and down, ultrapure
MANGANESE AA/ICP CALIBRATION/CHECK STANDARD
Manganese powder, >=99.9% trace metals basis
MANGANESE ATOMIC ABSORPTION STANDARD SOLUTION
MANGANESE PLASMA EMISSION SPECTROSCOPY STANDARD
Manganese, plasma standard solution, Mn 10μg/mL
Manganese powder, -100 mesh, 99% (metals basis)
Manganese rod, 50mm, diameter 4.0mm, cast, 99.5%
MANGANESE PIECES, IRREGULAR, 99.99% (METALS BASIS)
Manganese Oil based standard solution, Mn 1000μg/g
Manganese standard solution, 1 mg/ml Mn in 2% HNO3
Manganese plasma standard solution, Mn 10,000μg/mL
MANGANESE ATOMIC ABSORPTION SINGLE ELEMENT STANDARD
Manganese, Oil based standard solution, Mn 5000μg/g
Manganese powder, -325 mesh, 99% trace metals basis
Manganese pieces, ≤10mm, 99.9995% trace metals basis
Manganese, Reference Standard Solution, 1000ppm ± 1%
Standard solution for the determination of manganese
Manganese pieces, irregular, 99.9% trace metals basis
Manganese pieces, irregular, 99.95% trace metals basis
Manganese powder, -325 mesh, 99.95% trace metals basis
Manganese powder, APS <10 micron, 99.6% (metals basis)
Manganese granules, 0.8-10mm, 99.98% trace metals basis
Manganese nanopowder, APS 30-50nm, 99.9% (metals basis)
Manganese, plasma standard solution, Specpure, Mn 10g/ml
Manganese, AAS standard solution, Specpure(R), Mn 1000μg/ml
MANGANESE GRANULES, 0.8-3MM (0.03-0.12IN), 99.99% (METALS BA
Manganese, plasma standard solution, Specpure(R), Mn 1000μg/ml
MANGANESE, METAL, 99%MANGANESE, METAL, 99%MANGANESE, METAL, 99%
Manganese, Oil based standard solution, Specpure(R), Mn 5000μg/g
Manganese, Oil based standard solution, Specpure(R), Mn 1000μg/g
Manganese, plasma standard solution, Specpure(R), Mn 10,000μg/ml
Manganese pieces, 10mm & down, ultrapure, 99.9998% (metals basis)
Manganese granules, 0.8-10mm (0.03-0.40in), 99.98% (metals basis)
Internal Standard - Manganese@0.0500 % w/w in Xylenes:Mineral oil (50:50)
Manganese nanopowder, 99.9%, particle size: 80 - 100 nm, SSA: 20 - 35 m2/g
Manganese sputtering target, 76.2mm (3.0 in.) dia. x 3.18mm (0.125 in.) thick
Manganese sputtering target, 76.2mm (3.0 in.) dia. x 6.35mm (0.250 in.) thick
Manganese sputtering target, 50.8mm (2.0 in.) dia. x 6.35mm (0.250 in.) thick
Manganese sputtering target, 50.8mm (2.0 in.) dia. x 3.18mm (0.125 in.) thick
Manganese, ultrapure, 99.9998% (Metals basis), pieces 10MM and down, aMpouled
MANGANESE, METAL, 99.98%MANGANESE, METAL, 99.98%MANGANESE, METAL, 99.98%MANGANESE, METAL, 99.98% | [EINECS(EC#)]
231-869-6 | [Molecular Formula]
Mn | [MDL Number]
MFCD00011111 | [Molecular Weight]
54.94 | [MOL File]
7439-96-5.mol |
| Chemical Properties | Back Directory | [Definition]
Metallic element of atomic
number 25, group VIIB of periodic table, aw
64.9380, valences = 2, 3, 4, 6, 7; no stable isotopes;
four artificial radioisotopes. | [Appearance]
Manganese is a combustible, lustrous, brittle,
silvery soft metal. It may be found in chunks, powder, or
flakes. The most important ore containing manganese is
pyrolusite. Manganese may also be produced from ferrous
scrap used in the production of electric and open-hearth
steel. | [Melting point ]
1244 °C (lit.) | [Boiling point ]
1962 °C (lit.) | [density ]
7.3 g/mL at 25 °C(lit.)
| [vapor pressure ]
0-0Pa at 20℃ | [Fp ]
450℃ | [storage temp. ]
2-8°C
| [solubility ]
H2O: soluble
| [form ]
Powder | [color ]
Gray-brown to brown-black | [Specific Gravity]
7.2 | [PH]
<1 (H2O, 20°C) | [Stability:]
Stable. Incompatible with water, strong oxidizing agents, strong acids, phosphorus. | [Resistivity]
185 μΩ-cm, 20°C | [Water Solubility ]
Soluble in diluted acids. Insoluble in water. | [Merck ]
13,5745 | [Exposure limits]
Ceiling: 5 mg(Mn)/m3 (ACGIH and OSHA)
TWA: 1 mg(Mn)/m3 (NIOSH). | [InChIKey]
PWHULOQIROXLJO-UHFFFAOYSA-N | [History]
Recognized by Scheele, Bergman, and others as an element and isolated by Gahn in 1774 by reduction of the dioxide with carbon. Manganese minerals are widely distributed; oxides, silicates, and carbonates are the most common. The discovery of large quantities of manganese nodules on the floor of the oceans holds promise as a source of manganese. These nodules contain about 24% manganese together with many other elements in lesser abundance. Most manganese today is obtained from ores found in Ukraine, Brazil, Australia, Republic of So. Africa, Gabon, China, and India. Pyrolusite (MnO2) and rhodochrosite (MnCO3) are among the most common manganese minerals. The metal is obtained by reduction of the oxide with sodium, magnesium, aluminum, or by electrolysis. It is gray-white, resembling iron, but is harder and very brittle. The metal is reactive chemically, and decomposes in cold water slowly. Manganese is used to form many important alloys. In steel, manganese improves the rolling and forging qualities, strength, toughness, stiffness, wear resistance, hardness, and hardenability. With aluminum and antimony, especially with small amounts of copper, it forms highly ferromagnetic alloys. Manganese metal is ferromagnetic only after special treatment. The pure metal exists in four allotropic forms. The alpha form is stable at ordinary temperature; gamma manganese, which changes to alpha at ordinary temperatures, is soft, easily cut, and capable of being bent. The dioxide (pyrolusite) is used as a depolarizer in dry cells, and is used to “decolorize” glass that is colored green by impurities of iron. Manganese by itself colors glass an amethyst color, and is responsible for the color of true amethyst. The dioxide is also used in the preparation of oxygen and chlorine, and in drying black paints. The permanganate is a powerful oxidizing agent and is used in quantitative analysis and in medicine. Manganese is widely distributed throughout the animal kingdom. It is an important trace element and may be essential for utilization of vitamin B1. Twenty-seven isotopes and isomers are known. Manganese metal (99.95%) is priced at about $800/kg. Metal of 99.6% purity is priced at about $80/kg. | [Uses]
Manganese is a metallic element that functions as a nutrient and
dietary supplement. it is necessary for normal bone and tendon
structure, central nervous system functionality, and glucose utiliza-
tion. sources include manganese carbonate, chloride, oxides, and
sulfates. these sources differ in solubility. | [CAS DataBase Reference]
7439-96-5(CAS DataBase Reference) | [NIST Chemistry Reference]
Manganese(7439-96-5) | [EPA Substance Registry System]
7439-96-5(EPA Substance) |
| Safety Data | Back Directory | [Hazard Codes ]
F,Xi,T | [Risk Statements ]
R36/38:Irritating to eyes and skin .
R15:Contact with water liberates extremely flammable gases.
R11:Highly Flammable.
R34:Causes burns.
R23/24/25:Toxic by inhalation, in contact with skin and if swallowed . | [Safety Statements ]
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .
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) .
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice .
S36:Wear suitable protective clothing .
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection .
S27:Take off immediately all contaminated clothing . | [RIDADR ]
UN 3264 8/PG 3
| [WGK Germany ]
2
| [RTECS ]
OO9625000
| [TSCA ]
Yes | [HazardClass ]
8 | [PackingGroup ]
III | [HS Code ]
81110090 | [Safety Profile]
Human systemic effects
by inhalation: degenerative brain changes,
change in motor activity, muscle weakness.
A skin and eye irritant. Questionable
carcinogen with experimental tumorigenic
data. Flammable and moderately explosive
in the form of dust or powder when
exposed to flame. The dust ma)' be
pyrophoric in air and may explode when
heated in carbon dioxide. Murtures of
aluminum dust and manganese dust may
explode in air. mxtures with ammonium
nitrate may explode when heated. The
powdered metal igmtes on contact with
fluorine, chlorine + heat, hydrogen
peroxide, bromine pentafluoride, sulfur
dioxide + heat. Violent reaction with NO2
and oxidants. Incandescent reaction with
phosphorus, nitryl fluoride, nitric acid. Wdl
react with water or steam to produce
hydrogen; can react with oxidizing materials.
To fight fire, use special dry chemical. See
also MANGANESE COMPOUNDS. | [Hazardous Substances Data]
7439-96-5(Hazardous Substances Data) | [IDLA]
500 mg Mn/m3 |
| Hazard Information | Back Directory | [General Description]
A lustrous brittle silvery solid. | [Reactivity Profile]
Manganese dust(finely divided) has been known to be pyrophoric. Powdered manganese ignites in chlorine and burns brilliantly; with fluorine the reaction takes place with incandescence [Mellor 12:185, 344. 1946-47]. Concentrated nitric acid reacts with manganese with incandescence and a feeble explosion [Mellor 12:188. 1946-47]. Manganese or potassium ignites in nitrogen dioxide [Ann. Chim. et Phys.(2) 2:317]. Manganese burns with a brilliant flame when heated in sulfur dioxide vapor [Mellor 12:187. 1946-47]. Contact with conc. hydrogen peroxide causes violent decomposition and/or ignition. | [Air & Water Reactions]
During a fire in an industrial bag filter, a mixture of aluminum and MANGANESE(7439-96-5) dusts was released and an explosion resulted [Occ. Haz. 28:185-7. 1946-47]. | [Hazard]
Dust or powder is flammable. Use dry
chemical to extinguish. Toxic. Central nervous system impairment. Questionable carcinogen. | [Potential Exposure]
Manganese is used in the production
of steel; and in the manufacture of welding rod coatings
and fluxes; in the iron and steel industry in steel alloys,
e.g., ferro-manganese, silico-manganese, manganin, spiegeleisen; and as an agent to reduce oxygen and sulfur content of molten steel. Other alloys may be formed with
copper, zinc, and aluminum. Manganese and its compounds
are utilized in the manufacture of dry cell batteries (MnO2),
paints, varnishes, inks, dyes, matches, and firework; as a
fertilizer, disinfectant, bleaching agent; laboratory reagent;
drier for oils; an oxidizing agent in the chemical industry
particularly in the synthesis of potassium permanganate;
and as a decolorizer and coloring agent in the glass and
ceramics industry. Exposure may occur during the mining,
smelting, and refining of manganese; in the production
of various materials; and in welding operations with
manganese-coated rods. Manganese normally is ingested
as a trace nutrient in food. The average human intake is
approximately 10 mg/day | [First aid]
If 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, including 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 medical attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit.
The symptoms of metal fume fever may be delayed
for 412 hours following exposure: it may last less than
36 hours. Medical observation is recommended | [Shipping]
UN3089 Metal powders, flammable, n.o.s.,
Hazard Class: 4.1; Labels: 4.1-Flammable solid. UN3077Environmentally hazardous substances, solid, n.o.s., Hazard
class: 9; Labels: 9-Miscellaneous hazardous material,
Technical Name Required | [Incompatibilities]
Dust, powder, or finely divided material
has been known to be pyrophoric or explosive in air.
Compact, solid metallic magnesium is nonflammable.
Reacts with water (slowly), steam, or acid producing flammable hydrogen gas. Reacts violently with concentrated hydrogen peroxide. Incompatible with nitrogen
gas above 200C. Oxidizers, nitric acid; nitrogen, finely
divided aluminum and other metals; sulfur dioxide; carbon
dioxide 1 heat may cause fire and explosions | [Description]
Manganese occurs as a free element in nature and is ubiquitous
in the environment. The origin and uses of this black mineral
date back to the Greek golden period. Manganese was known
as pyrolusite or manganese dioxide. A Swedish chemist, Carl
Wilhelm Scheele, used pyrolusite to produce chlorine in the
mid-eighteenth century. But not until 1774 was manganese
isolated and purified as a metal by Johan Gottlieb Gahn by
reducing the dioxide with carbon. Manganese is an essential
element for humans and animals. | [Chemical Properties]
Manganese is a combustible, lustrous, brittle,
silvery soft metal. It may be found in chunks, powder, or
flakes. The most important ore containing manganese is
pyrolusite. Manganese may also be produced from ferrous
scrap used in the production of electric and open-hearth
steel. | [Waste Disposal]
Generators of waste (equal to
or greater than 100 kg/mo) containing this contaminant,
EPA hazardous waste number N450, must conform to
USEPA regulations for storage, transportation, treatment,
and disposal of waste. Dispose of waste material as hazardous waste using a licensed disposal contractor to an
approved landfill. Dispose of contents and container to an
approved waste disposal plant. Containers must be disposed
of properly by following package label directions or by
contacting your local or federal environmental control
agency, or by contacting your regional EPA office. All
federal, state, and local environmental regulations must
be observed. Do not discharge into drains or sewers.
Manganese metal-sanitary landfill. Manganese chloride or
sulfate-chemical conversion to the oxide followed by land
filling, or conversion to the sulfate for use in fertilizer.
Consult with environmental regulatory agencies for guidance on acceptable disposal practices. | [Isotopes]
There are 30 isotopes of manganese, ranging from Mn-44 to Mn-69, with onlyone being stable: Mn-55 makes up 100% of the element in the Earth’s crust. All theother isotopes are artificially radioactive with half-lives ranging from 70 nanoseconds to3.7×106 years. Artificial radioisotopes are produced in nuclear reactors, and becausemost radioactive isotopes are not natural, they do not contribute to the element’s naturalexistence on Earth. | [Origin of Name]
The name manganese is derived from the mineral magnesite (or dolomite, a compound of magnesium carbonate), which was mined in the region of Magnesia of ancient Greece. | [Occurrence]
Manganese minerals are widely distributed across the Earth as oxides, silicates, and carbonates. Manganese is the 11th most abundant element found in the Earth’s crust, and manganeseoxide minerals are the 10th most abundant compounds in the Earth’s crust. Pure manganeseis found in meteorites that land on Earth’s surface. Its minerals psilomelane, pyrolusite, rhodichrosite, and manganite (manganese ore) are found in most countries. It is also found inlow-grade iron ores and in slag as a by-product of iron smelting. Manganese ores are foundin India, Brazil, the Republic of South Africa, Gabon, Australia, and Russia, as well as in thestate of Montana in the United States.Huge amounts (i.e., more than 1012 tons) of manganese cover vast regions of the oceanbeds, and more than 107 tons are newly deposited each year. When recovered nodules (lumps)are removed and dried, they contain between 15% and 35% Mn, which is below the requirement for commercial mining. In addition, smaller amounts of cobalt, nickel, and copper arefound in these manganese “nodules.” Proposals to mine the nodules have been suggested, butno large quantities have been recovered. Mining of the ocean floors for manganese will probably not occur until the sources on Earth become more scarce and expensive to exploit, whichis not likely to happen any time soon. Meanwhile, these nodule deposits serve as a reserve forseveral important metals.In addition to reduction of its ores in furnaces, manganese can be produced by electrolysis. The electrolyte is manganese sulfate that is produced by treating ore with sulfuric acid,(2MnO2 + 2H2SO4 → 2MnSO4 + O2 + 2H2O). The anode is lead alloy, and the cathode ismade of a steel alloy. Pure (about 99%) manganese metal collects at the cathode, and in theprocess, the manganese sulfate is converted back to sulfuric acid, which can be reused to reactwith more MnO2 ore. | [Characteristics]
There are four allotropic forms of manganese, which means each of its allotropes has a different crystal form and molecular structure. Therefore, each allotrope exhibits different chemical and physical properties (see the forms of carbon—diamond, carbon black, and graphite).The alpha (α) allotrope is stable at room temperature whereas the gamma (γ) form is soft,bendable, and easy to cut. The delta ? allotrope exists only at temperatures above 1,100°C. Asa pure metal, it cannot be worked into different shapes because it is too brittle. Manganese isresponsible for the color in amethyst crystals and is used to make amethyst-colored glass. | [Production Methods]
World manganese ore production was estimated to be
13.3 million ton (as manganese) in 2008. Top five
manganese-producing countries were South Africa,
Australia, China, Gabon, and Brazil. World manganese
ferroalloy production in 2008 was 13.2 million ton (MT)
(10). Metallurgical applications account for most manganese
consumption. In the United States, 85–90% of this is for
steelmaking. Manganese is essential in iron and steel
production because of its sulfur-fixing, deoxidizing, and
alloying properties. As an alloying agent in finished steel,
manganese contributes increased strength, hardness, and
corrosion resistance. Practically all steels contain manganese;
low-carbon steels contain 0.15–0.8% manganese,
whereas high-strength steels contain over 1% manganese.
Stainless steels typically contain about 1% manganese, but
there are manganese-stainless steels (200 series stainless
steels) where nickel is replaced partly or entirely by manganese,
resulting in manganese content of 4–16%. | [Health Hazard]
Couper in 1837 observed that manganesedust produced a neurological syndrome similarto those of Parkinson’s disease. Thesymptoms were muscle weakness, tremor,bent posture, excess salivation and whisperedspeech. Excess manganese can accumulatein brain tissue to cause such neurodegenerativedisorder known as manganism, a diseasewith Parkinson-like symptoms, evokingsevere psychiatric and extrapyramidal motorfunction. The clinical manifestation of suchtoxicity arises from the focal injury to basalganglia, a region characterized by intenseconsumption of oxygen and high dopaminecontent. Chronic manganese exposure probablyincurs mitochondrial dysfunction, depletionof levels of enzymes peroxidase andcatalase, as well as, biochemical imbalancesof catecholamine in this brain region. Suchexposures may eventually produce cytotoxiclevels of free radicals causing cellular damage.The mechanism of neurodegenerativedamage, however, is not clearly understood.Disturbances in iron homeostasis and valencestate of manganese have been cited as keyfactors in contributing to manganese toxicity(Crossgrove and Zheng 2004). Oxidativebasis of manganese neurotoxicity andprogression of manganism is well reviewed(HaMai and Bondy 2004; Dobson et al.2004; Levy and Nassetta 2003).
Yang et al (2005) have proposed an alternatepathway of manganese induced neurotoxicitythat involved eukaryotic ACDP(ancient conserved domain protein) familyprotein in metal homoeostasis. These authorsemployed the baker’s yeast Saccharomycescerevisiae as a model system to identifygenes that contributed to manganese-relateddamage.
The treatment against Mn toxicity includechelation therapy with EDTA and supplementationwith levodopa.
| [Flammability and Explosibility]
Notclassified | [Agricultural Uses]
Manganese (Mn) is a transition element with atomic number 25 and atomic weight 54.93. It belongs to Group 7 of the Periodic Table and is anessential plant nutrient which plays an important role in plant biochemical processes. It is absorbed by plants in the form of manganese ions (Mn2+) or as an organic complex. In green plants, manganese influences the light-dependent water splitting reaction (Hill reaction) and oxygen evolution during photosynthesis. Manganese provides oxygen to poorly ventilated interior soil pores, where iron in the form of ferrous ion (Fe2+) and complex organic molecules would otherwise remain nonoxidized.
Manganese is associated with several enzyme systems and electron transport. It exists as manganese ion (Mn2+) in plant cells in many complex forms. It can form metalloproteins and is tightly bound in chloroplast with its average concentration of 100 ppm in the plant cell.
Manganese serves as a co-factor or a prosthetic group of enzymes involved in reactions concerned with oxidation-reduction, carboxylation, decarboxylation, photophosphorylation and hydrolysis. It affects respiration, amino acid synthesis, lignin biosynthesis and hormone levels in plants. It regulates the metabolism of carbohydrates, proteins, nucleic acids, secondary metabolites, ascorbic acid and citric acid cycles. With other metals, it works in the activation of enzymes such as arginase, cysteine desulphydrase, deoxyribonuclease and yeast phosphatase. Manganese is a specific activator of the enzyme, namely, prolidase and glutamyl transferase.
| [Environmental Fate]
Higher levels of environmental exposures to manganese are
most likely to occur in or near a factory or a waste site that
releases manganese dust into air. Manganese is also released
into air by combustion of unleaded gasoline that contains
manganese as an antiknock ingredient. Some manganese
compounds are readily soluble, so significant exposures can
also occur by ingestion of contaminated drinking water.
However, manganese in surface water may oxidize or adsorb to
sediment particles and settle out. Manganese in soil can migrate
as particulate matter to air or water, or soluble compounds may
be dissolved by water and leached from the soil. Elemental
manganese and inorganic manganese compounds have negligible
vapor pressures, but may exist in air as suspended
particulate matter derived from industrial emissions or the
erosion of soils. The half-life of airborne particles is usually on
the order of days, depending on the size of the particle and
atmospheric conditions.
The transport and partitioning of manganese in water are
controlled by the solubility of the specific chemical form present,
which in turn is determined by pH, Eh (oxidation–reduction
potential), and the characteristics of available anions. The
metal may exist in water in any of four oxidation states (2+,
3+, 4+, or 7+). Divalent manganese (Mn2+) predominates in
most waters (pH 4–7), but may become oxidized at pH
greater than 8 or 9. The principal anion associated with Mn2+
in water is usually carbonate (CO3
2), and the concentration
of manganese is limited by the relatively low solubility
(65 mg l-1) of MnCO2. In relatively oxidized water, the
solubility of Mn2+ may be controlled by manganese oxide
equilibria, with manganese being converted to the (3+) or
(4+) valence state. In extremely reduced water, the fate of
manganese tends to be controlled by the formation of the
poorly soluble sulfide.
Manganese in water may be significantly bioconcentrated at
lower trophic levels.
Manganese is a natural component ofmost foods. The highest
manganese concentrations (up to 40 ppm) are found in nuts and
grains, with lower levels (up to 4 ppm) found in milk products,
meats, fish, and eggs. Concentrations of manganese in infant
formulas range from 34 to 1000 ppb, compared to concentrations
of 10 ppb in human milk and 30 ppb in cow’s milk. | [storage]
Color Code—Green: General storage may be used. Prior to working with this chemical you should be trained on its proper handling and storage. Manganese must be stored to avoid contact with water and steam since flammable hydrogen gas is produced. Store in tightly closed containers in a cool, well-ventilated area away from oxidizers (such as perchlorates, peroxides, permanganates, chlorates and nitrates). Protect storage against physical damage. | [Toxicity evaluation]
Manganese [7439-96-5] is an integral part of the
superoxide dismutase and of the electron donor complex
of photosystem II. Manganese may activate enzymes in
the same way as Mg2+ by bridging the phosphate group
with the enzyme or the substrate. Deficiency of Mn2+
leads to the breakdown of chloroplasts. Characteristic
deficiency symptoms are smaller yellow spots on the
leaves and interveinal chlorosis. Manganese toxicity may
occur, especially on flooded soils, because of the reduction
and thus solubilization of manganese oxides. Toxicity
symptoms are generally characterized by brown spots
of MnO2 in the older leaves surrounded by chlorotic
areas (29). |
| Questions And Answer | Back Directory | [History, Occurrence, and Uses]
Manganese was recognized as an element by Scheele, Bergman and others in 1774 and isolated by Gahn in the same year. Gahn obtained the metal by thermal reduction of pyrolusite with carbon. The element derived its name from the Latin word, magnes which means magnet, referring to the magnetic properties of its ore pyrolusite.
Manganese is distributed widely in nature, mostly as oxide, silicate, and carbonate ores. Manganese ores often are found in association with iron ores in small quantities. The element, however, does not occur naturally in native form. Manganese is the twelfth most abundant element in the earth’s crust. Its concentration in the earth’s crust is estimated to be 0.095%. Its average concentration in seawater is 2μg/L. Manganese also is found in large quantities in deep-sea nodules over the ocean floor at depths of 2.5 to 4 miles.
Manganese is used widely in industry: the most important use is in ferrous metallurgy. It also is used in chemical, electrochemical, food and pharmaceutical applications. Ferromanganese alloys are used in steel manufacturing.
Manganese serves as a deoxidizer of molten steel and controls its sulfur content. Manganese metal also enhances strength and hardness of the alloy, and its resistance to corrosion. Manganese is used in high-temperature steels, stainless steels, manganese steel and various nickel-chromium and manganesealuminum alloys. Practically all aluminum and magnesium alloys contain manganese.
Manganese is an essential element for plants and animals. Its shortage in soil can cause chlorosis or lack of chlorophyll in plants—manifested by the appearance of yellow or grey streaks on the leaves or mottling. It activates certain plant enzymes, such as oxalosuccinic decacarboxylase in the oxidation of carbohydrates. Manganese deficiency can cause deformity of bones in animals. In chemical industries, manganese is used to prepare several compounds.
| [Physical Properties]
Reddish-gray metal; exists in four allotropic modifications: alpha-, beta-, gammaand delta forms. Alpha form has cubic crystal structure; 58 atoms per unit cell; density 7.43 g/cm3; brittle; transforms to beta form at 720°C. Betamanganese is brittle and has a cubic lattice structure; containing 20 atoms per unit cube; transforms to gamma form at 1,100°C or back to alpha form on cooling; density 7.29 g/cm3. The gamma form exists as face-centered cubic crystal containing 4 atoms per unit cell; density 7.18 g/cm3; converts to delta form at 1,136°C. Delta-manganese consists of body-centered cubic crystals containing 2 atoms per unit cube; density 6.30 g/cm3; stable up to 1,244°C above which it melts to liquid.
Manganese vaporizes at 2,097°C; vapor pressure 0.9 torr at 1,244°C; hardness 5.0 (Mohs scale); magnetic susceptibility 9.9 cgs units at 18°C; electrical resistivities 185, 44, and 60 microhm–cm at 20°C for alpha-, betaand gamma allotropes respectively; thermal neutron absorption 13.2 barns.
| [Production]
Manganese is recovered primarily from its oxide ores, the most important being pyrolusite, MnO2. The basic method of producing the metal has not changed much since Gahn first isolated it by reducing manganese dioxide with carbon. Several processes to produce manganese meet its high demand in ferrous metallurgy. The oxides are reduced thermally in an electric furnace or a blast furnace. The ore is smelted at high temperatures in the presence of carbon, which reduces higher oxides of manganese, MnO2, Mn2O3, and Mn3O4 into MnO, and then forms metallic manganese which has a relatively high vapor pressure:
Selection of the process depends on the requirement of the product, such as high-carbon or low-carbon ferromanganese or silicomanganese of varying carbon contents. Usually coke is used as a reducing agent for high-carbon ferromanganese for the steel industry. Low-carbon ferromanganese, silicomanganese, or refined ferromanganese that has low carbon content ranging from 0.1 to 1.5% maximum carbon, may be obtained by using silicon as a reducing agent:
MnO2 + Si → Mn + SiO2
Mn3O4 + 2Si → 3Mn + SiO2
2MnO + Si → 2Mn + SiO2
Often, the manganese ores contain several other naturally occurring metal oxides such as alumina, silica, magnesia, and lime. Some of these oxides may be blended into manganese ore as fluxes to the furnace charge.
Manganese may be produced by electrolytic processes. Aqueous solutions of manganese(II) sulfate are used as the electrolyte. Mn ore is roasted and reduced with carbon or silicon to convert the higher oxides of manganese into MnO. The products are then leached with dilute sulfuric acid at pH 3. MnO dissolves in the acid forming manganese(II) sulfate. The solution is filtered and separated from insoluble residues. It then is neturalized with ammonia to pH 6–7.
Iron and aluminum precipitate out when treated with ammonia and are removed by filtration. Other metals, such as copper, zinc, lead and arsenic are precipitated and removed as sulfides upon passing hydrogen sufide through the solution. Colloidal particles of metallic sulfides and sulfur are removed by treatment with iron(II) sulfide. The purified solution of manganese(II) sulfate is then electrolyzed in an electrolytic cell using lead anode and Hastelloy or Type 316 stainless steel cathode, both of which are resistant to acid. Manganese is deposited on the cathode as a thin film.
Manganese also is produced by electrolysis of fused salt. In one such process, the reduced MnO is blended to molten calcium fluoride and lime. The latter is used to neutralize silica in the ore. The fused composition of these salts is electrolyzed at 1,300°C in an electrolytic cell made up of high temperature ceramic material, using a carbon anode and a cathode consisting of iron bars internally cooled by water.
| [Toxicity]
Although trace amounts of manganese are essential for animals, in large quantities the metal can cause acute and chronic poisoning. Chronic inhalation of metal dust or fumes can cause manganism, a nonfatal disease affecting the central nervous system. The symptoms are mental disorder and disturbance in speech.
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