Radiochemistry
Encyclopedia
Radiochemistry is the chemistry
of radioactive materials, where radioactive isotope
s of elements are used to study the properties and chemical reaction
s of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads to a substance being described as being inactive as the isotopes are stable). Much of radiochemistry deals with the use of radioactivity to study ordinary chemical reaction
s.
Radiochemistry includes the study of both natural and man-made radioisotopes.
s of elements
—undergo nuclear decay and emit some form of radiation
. The radiation emitted can be one of three types, called alpha
, beta
, or gamma radiation.
1. α (alpha) radiation - the emission of an alpha particle
(which contains 2 protons and 2 neutrons) from an atomic nucleus
. When this occurs, the atom’s atomic mass
will decrease by 4 units and atomic number
will decrease by 2.
2. β (beta) radiation - the transmutation
of a neutron
into an electron
and a proton
. After this happens, the electron is emitted from the nucleus into the electron cloud.
3. gamma radiation - the emission of electromagnetic energy (such as X-rays) from the nucleus of an atom. This usually occurs during alpha or beta radioactive decay
.
These three types of radiation can be distinguished by their difference in penetrating power.
Alpha can be stopped quite easily by a few centimetres in air or a piece of paper and is equivalent to a helium nucleus. Beta can be cut off by an aluminium sheet just a few millimetres thick and are electrons. Gamma is the most penetrating of the three and is a massless chargeless high energy photon
. Gamma radiation requires an appreciable amount of heavy metal radiation shielding (usually lead
or barium
-based) to reduce its intensity.
irradiation of objects it is possible to induce radioactivity; this activation of stable isotopes to create radioisotopes is the basis of neutron activation analysis
. One of the most interesting objects which has been studied in this way is the hair of Napoleon's head, which have been examined for their arsenic
content.
A series of different experimental methods exist, these have been designed to enable the measurement of a range of different elements in different matrices. To reduce the effect of the matrix
it is common to use the chemical extraction of the wanted element and/or to allow the radioactivity due to the matrix elements to decay before the measurement of the radioactivity. Since the matrix effect can be corrected for by observing the decay spectrum, little or no sample preparation is required for some samples, making neutron activation analysis less susceptible to contamination.
The effects of a series of different cooling times can be seen if a hypothetical sample which contains sodium, uranium and cobalt in a 100:10:1 ratio was subjected to a very short pulse of thermal neutrons. The initial radioactivity would be dominated by the 24Na activity (half-life
15 h) but with increasing time the 239Np (half-life 2.4 d after formation from parent 239U with half-life 24 min) and finally the 60Co activity (5.3 yr) would predominate.
using radioactive phosphorus
-32. In these experiments stable phosphorus is replaced by the chemical identical radioactive P-32, and the resulting radioactivity is used in analysis of the molecules and their behaviour.
Another example is the work which was done on the methylation of elements such as sulfur
, selenium
, tellurium and polonium
by living organisms. It has been shown that bacteria
can convert these elements into volatile compounds, it is thought that methylcobalamin (vitamin
B12
) alkylates these elements to create the dimethyls. It has been shown that a combination of Cobaloxime and inorganic polonium in sterile
water forms a volatile polonium compound, while a control experiment which did not contain the cobalt
compound did not form the volatile polonium compound. For the sulfur
work the isotope 35S was used, while for polonium 207Po was used. In some related work by the addition of 57Co to the bacterial culture, followed by isolation of the cobalamin from the bacteria (and the measurement of the radioactivity of the isolated cobalamin) it was shown that the bacteria convert available cobalt into methylcobalamin.
and the radioactivity in the air downwind was measured.
It is important to note that a vast number of processes are able to release radioactivity into the environment, for example the action of cosmic ray
s on the air is responsible for the formation of radioisotopes (such as 14C and 32P), the decay of 226Ra forms 222Rn which is a gas which can diffuse through rocks before entering buildings and dissolve in water and thus enter drinking water
in addition human activities such as bomb tests, accidents, and normal releases from industry have resulted in the release of radioactivity.
and as a result many different oxidation states can coexist at once. Some work has been done on the identification of the oxidation state and coordination number of plutonium and the other actinides under different conditions has been done.http://www.fas.org/sgp/othergov/doe/lanl/pubs/00818043.pdf This includes work on both solutions of relatively simple complexes and work on colloids Two of the key matrixes are soil
/rocks and concrete
, in these systems the chemical properties of plutonium have been studied using methods such as EXAFS and XANES
.http://www.wmsym.org/Abstracts/2002/Proceedings/6b/188.pdfhttp://www.lanl.gov/orgs/nmt/nmtdo/AQarchive/02spring/synchrotron.html
, one kilogram of soil typically contains the following amounts of the following three natural radioisotopes 370 Bq 40K (typical range 100-700 Bq), 25 Bq 226Ra (typical range 10-50 Bq), 25 Bq 238U (typical range 10-50 Bq) and 25 Bq 232Th (typical range 7-50 Bq).
can use chromium
(VI), iron
(III), cobalt
(III), manganese
(IV) and uranium(VI) as electron acceptors while acetate
, glucose
, hydrogen
, lactate
, pyruvate, succinate, and xylose
can act as electron donors for the metabolism of the bacteria. In this way the metals can be reduced to form magnetite
(Fe3O4), siderite
(FeCO3), rhodochrosite
(MnCO3), and uraninite
(UO2). Other researchers have also worked on the fixing of uranium using bacteriahttp://www.physorg.com/news67270244.htmlhttp://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.pbio.0040282http://www.pnl.gov/news/release.asp?id=175, Francis R. Livens et al. (Working at Manchester
) have suggested that the reason why Geobacter sulfurreducens can reduce UO22+ cations to uranium dioxide is that the bacteria reduce the uranyl cations to UO2+ which then undergoes disproportionation to form UO22+ and UO2. This reasoning was based (at least in part) on the observation that NpO2+ is not converted to an insoluble neptunium oxide by the bacteria.
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
of radioactive materials, where radioactive isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s of elements are used to study the properties and chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
s of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads to a substance being described as being inactive as the isotopes are stable). Much of radiochemistry deals with the use of radioactivity to study ordinary chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
s.
Radiochemistry includes the study of both natural and man-made radioisotopes.
Main decay modes
All radioisotopes are unstable isotopeIsotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s of elements
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...
—undergo nuclear decay and emit some form of radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
. The radiation emitted can be one of three types, called alpha
Alpha particle
Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus, which is classically produced in the process of alpha decay, but may be produced also in other ways and given the same name...
, beta
Beta particle
Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. The production of beta particles is termed beta decay...
, or gamma radiation.
1. α (alpha) radiation - the emission of an alpha particle
Alpha particle
Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus, which is classically produced in the process of alpha decay, but may be produced also in other ways and given the same name...
(which contains 2 protons and 2 neutrons) from an atomic nucleus
Atomic nucleus
The nucleus is the very dense region consisting of protons and neutrons at the center of an atom. It was discovered in 1911, as a result of Ernest Rutherford's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest Marsden, under the direction of Rutherford. The...
. When this occurs, the atom’s atomic mass
Atomic mass
The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
will decrease by 4 units and atomic number
Atomic number
In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
will decrease by 2.
2. β (beta) radiation - the transmutation
Nuclear transmutation
Nuclear transmutation is the conversion of one chemical element or isotope into another. In other words, atoms of one element can be changed into atoms of other element by 'transmutation'...
of a neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
into an electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
and a proton
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
. After this happens, the electron is emitted from the nucleus into the electron cloud.
3. gamma radiation - the emission of electromagnetic energy (such as X-rays) from the nucleus of an atom. This usually occurs during alpha or beta radioactive decay
Radioactive decay
Radioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
.
These three types of radiation can be distinguished by their difference in penetrating power.
Alpha can be stopped quite easily by a few centimetres in air or a piece of paper and is equivalent to a helium nucleus. Beta can be cut off by an aluminium sheet just a few millimetres thick and are electrons. Gamma is the most penetrating of the three and is a massless chargeless high energy photon
Photon
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
. Gamma radiation requires an appreciable amount of heavy metal radiation shielding (usually lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
or barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
-based) to reduce its intensity.
Activation analysis
By neutronNeutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
irradiation of objects it is possible to induce radioactivity; this activation of stable isotopes to create radioisotopes is the basis of neutron activation analysis
Neutron activation analysis
In chemistry, neutron activation analysis is a nuclear process used for determining the concentrations of elements in a vast amount of materials. NAA allows discrete sampling of elements as it disregards the chemical form of a sample, and focuses solely on its nucleus. The method is based on...
. One of the most interesting objects which has been studied in this way is the hair of Napoleon's head, which have been examined for their arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
content.
A series of different experimental methods exist, these have been designed to enable the measurement of a range of different elements in different matrices. To reduce the effect of the matrix
Matrix (chemical analysis)
In chemical analysis, matrix refers to the components of a sample other than the analyte. The matrix can have a considerable effect on the way the analysis is conducted and the quality of the results obtained; such effects are called matrix effects. For example, the ionic strength of the solution...
it is common to use the chemical extraction of the wanted element and/or to allow the radioactivity due to the matrix elements to decay before the measurement of the radioactivity. Since the matrix effect can be corrected for by observing the decay spectrum, little or no sample preparation is required for some samples, making neutron activation analysis less susceptible to contamination.
The effects of a series of different cooling times can be seen if a hypothetical sample which contains sodium, uranium and cobalt in a 100:10:1 ratio was subjected to a very short pulse of thermal neutrons. The initial radioactivity would be dominated by the 24Na activity (half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
15 h) but with increasing time the 239Np (half-life 2.4 d after formation from parent 239U with half-life 24 min) and finally the 60Co activity (5.3 yr) would predominate.
Biochemical uses
One biological application is the study of DNADNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
using radioactive phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
-32. In these experiments stable phosphorus is replaced by the chemical identical radioactive P-32, and the resulting radioactivity is used in analysis of the molecules and their behaviour.
Another example is the work which was done on the methylation of elements such as sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
, selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
, tellurium and polonium
Polonium
Polonium is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie Skłodowska-Curie and Pierre Curie. A rare and highly radioactive element, polonium is chemically similar to bismuth and tellurium, and it occurs in uranium ores. Polonium has been studied for...
by living organisms. It has been shown that bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
can convert these elements into volatile compounds, it is thought that methylcobalamin (vitamin
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...
B12
Vitamin B12
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...
) alkylates these elements to create the dimethyls. It has been shown that a combination of Cobaloxime and inorganic polonium in sterile
Asepsis
Asepsis is the state of being free from disease-causing contaminants or, preventing contact with microorganisms. The term asepsis often refers to those practices used to promote or induce asepsis in an operative field in surgery or medicine to prevent infection...
water forms a volatile polonium compound, while a control experiment which did not contain the cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
compound did not form the volatile polonium compound. For the sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
work the isotope 35S was used, while for polonium 207Po was used. In some related work by the addition of 57Co to the bacterial culture, followed by isolation of the cobalamin from the bacteria (and the measurement of the radioactivity of the isolated cobalamin) it was shown that the bacteria convert available cobalt into methylcobalamin.
Environmental
Radiochemistry also includes the study of the behaviour of radioisotopes in the environment; for instance, a forest or grass fire can make radioisotopes become mobile again. In these experiments, fires were started in the exclusion zone around ChernobylChernobyl
Chernobyl or Chornobyl is an abandoned city in northern Ukraine, in Kiev Oblast, near the border with Belarus. The city had been the administrative centre of the Chernobyl Raion since 1932....
and the radioactivity in the air downwind was measured.
It is important to note that a vast number of processes are able to release radioactivity into the environment, for example the action of cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...
s on the air is responsible for the formation of radioisotopes (such as 14C and 32P), the decay of 226Ra forms 222Rn which is a gas which can diffuse through rocks before entering buildings and dissolve in water and thus enter drinking water
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
in addition human activities such as bomb tests, accidents, and normal releases from industry have resulted in the release of radioactivity.
Chemical form of the actinides
The environmental chemistry of some radioactive elements such as plutonium is complicated by the fact that solutions of this element can undergo disproportionationDisproportionation
Disproportionation, also known as dismutation is used to describe a specific type of redox reaction in which a species is simultaneously reduced and oxidized so as to form two different products....
and as a result many different oxidation states can coexist at once. Some work has been done on the identification of the oxidation state and coordination number of plutonium and the other actinides under different conditions has been done.http://www.fas.org/sgp/othergov/doe/lanl/pubs/00818043.pdf This includes work on both solutions of relatively simple complexes and work on colloids Two of the key matrixes are soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
/rocks and concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
, in these systems the chemical properties of plutonium have been studied using methods such as EXAFS and XANES
XANES
X-ray Absorption Near Edge Structure , also known as Near edge X-ray absorption fine structure is a type of absorption spectroscopy. NEXAFS also at times used the abbreviation EXAFS....
.http://www.wmsym.org/Abstracts/2002/Proceedings/6b/188.pdfhttp://www.lanl.gov/orgs/nmt/nmtdo/AQarchive/02spring/synchrotron.html
Movement of colloids
While binding of a metal to the surfaces of the soil particles can prevent its movement through a layer of soil, it is possible for the particles of soil which bear the radioactive metal can migrate as colloidal particles through soil. This has been shown to occur using soil particles labeled with 134Cs, these have been shown to be able to move through cracks in the soil.Normal background
Radioactivity is present everywhere (and has been since the formation of the earth). According to the International Atomic Energy AgencyInternational Atomic Energy Agency
The International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy, and to inhibit its use for any military purpose, including nuclear weapons. The IAEA was established as an autonomous organization on 29 July 1957...
, one kilogram of soil typically contains the following amounts of the following three natural radioisotopes 370 Bq 40K (typical range 100-700 Bq), 25 Bq 226Ra (typical range 10-50 Bq), 25 Bq 238U (typical range 10-50 Bq) and 25 Bq 232Th (typical range 7-50 Bq).
Action of microorganisms
The action of micro-organisms can fix uranium; ThermoanaerobacterThermoanaerobacter
Thermoanaerobacter is a genus in the phylum Firmicutes . Members of this genus are thermophilic and anaerobic, several of them were previously described as Clostridium species and members of the now obsolete genera Acetogenium and Thermobacteroides-Etymology:The name Thermoanaerobacter derives...
can use chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
(VI), iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
(III), cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
(III), manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
(IV) and uranium(VI) as electron acceptors while acetate
Acetate
An acetate is a derivative of acetic acid. This term includes salts and esters, as well as the anion found in solution. Most of the approximately 5 billion kilograms of acetic acid produced annually in industry are used in the production of acetates, which usually take the form of polymers. In...
, glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
, hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
, lactate
Lactic acid
Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Lactic acid is a carboxylic acid with the chemical formula C3H6O3...
, pyruvate, succinate, and xylose
Xylose
Xylose is a sugar first isolated from wood, and named for it. Xylose is classified as a monosaccharide of the aldopentose type, which means that it contains five carbon atoms and includes an aldehyde functional group. It is the precursor to hemicellulose, one of the main constituents of biomass...
can act as electron donors for the metabolism of the bacteria. In this way the metals can be reduced to form magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
(Fe3O4), siderite
Siderite
Siderite is a mineral composed of iron carbonate FeCO3. It takes its name from the Greek word σίδηρος sideros, “iron”. It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus...
(FeCO3), rhodochrosite
Rhodochrosite
Rhodochrosite is a manganese carbonate mineral with chemical composition MnCO3. In its pure form, it is typically a rose-red color, but impure specimens can be shades of pink to pale brown. The streak is white. Its Mohs hardness varies between 3.5 and 4. Its specific gravity is 3.5 to 3.7. It...
(MnCO3), and uraninite
Uraninite
Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2, but also contains UO3 and oxides of lead, thorium, and rare earth elements...
(UO2). Other researchers have also worked on the fixing of uranium using bacteriahttp://www.physorg.com/news67270244.htmlhttp://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.pbio.0040282http://www.pnl.gov/news/release.asp?id=175, Francis R. Livens et al. (Working at Manchester
Manchester
Manchester is a city and metropolitan borough in Greater Manchester, England. According to the Office for National Statistics, the 2010 mid-year population estimate for Manchester was 498,800. Manchester lies within one of the UK's largest metropolitan areas, the metropolitan county of Greater...
) have suggested that the reason why Geobacter sulfurreducens can reduce UO22+ cations to uranium dioxide is that the bacteria reduce the uranyl cations to UO2+ which then undergoes disproportionation to form UO22+ and UO2. This reasoning was based (at least in part) on the observation that NpO2+ is not converted to an insoluble neptunium oxide by the bacteria.