Eigencolloid is a term derived from the German language (''eigen'': own) and used to designate

colloid A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others exte ...

s made of pure phases, also known as intrinsic colloids. Eigencolloids are metal oxyhydroxide

s on the nanometer scale formed by aggregation of hydrolyzed metal ions. They are characterized by a very large specific surface area (up to 2000 m²/g) and a high reactivity. They hold promise for the development of new industrial

catalysts Catalysis () is the increase in reaction rate, rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst ...

. Many such colloids are formed by the

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

heavy metals upright=1.2, Crystals of lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals is a controversial and ambiguous term for metallic elements with relatively h ...

cations An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

s, such as, for example, Tc(OH)₄, Th(OH)₄, U(OH)₄, Pu(OH)₄, or Am(OH)₃. The term 'eigencolloid' or 'intrinsic colloid', is often used in distinction to a pseudocolloid. A pseudocolloid is one in which elements (

s or

) become adsorbed onto pre-existing

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

colloids due to their affinity to these colloids or to the

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

properties of the dispersing medium. In

environmental chemistry Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It should not be confused with green chemistry, which seeks to reduce potential pollution at its source. It can be defined as ...

, enhanced migration of heavy metal and radioactive metal contaminants in ground and surface waters is often facilitated by eigencolloid formation.

Actinide eigencolloids

Eigencolloid formation occurs readily in

upon storage of

radioactive waste Radioactive waste is a type of hazardous waste that contains radioactive material. It is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear ...

. Colloid-facilitated transport is a mechanism responsible for the mobilisation of

s into the wider environment, causing radioactive contamination. This is a

public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the de ...

concern since elevated radioactivity in the environment is

mutagenic In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer in ...

and can lead to

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

. Eigencolloids have been implicated in the long-range transport of

plutonium Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four ...

on the

Nevada Test Site The Nevada National Security Sites (N2S2 or NNSS), popularized as the Nevada Test Site (NTS) until 2010, is a reservation of the United States Department of Energy located in the southeastern portion of Nye County, Nevada, about northwest of ...

References

* * * Breynaert E. (2008). PhD Thesis. Catholic University of Leuven
Formation, stability and applications of eigencolloids of technetium.
* * {{cite journal , year = 2007 , title = Solubility of plutonium hydroxides/hydrous oxides under reducing conditions and in the presence of oxygen , journal = Comptes Rendus Chimie , volume = 10 , issue = 10–11 , pages = 959–977 , author1=Neck, V. , author2=Altmaier, M. , author3=Fanghänel, T. , doi = 10.1016/j.crci.2007.02.011 , url = https://comptes-rendus.academie-sciences.fr/chimie/articles/10.1016/j.crci.2007.02.011/ , url-access= subscription Actinides Colloids Colloidal chemistry

Actinide eigencolloids

See also

References