Eigencolloid is a term derived from the German language (eigen: own) and used to designatecolloids made of pure phases, also known asintrinsic colloids.
Eigencolloids are metal oxyhydroxidecolloids 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 industrialcatalysts.[1]
Many such colloids are formed by thehydrolysis ofheavy metalscations orradionuclides, such as, for example,Tc(OH)4,Th(OH)4,U(OH)4,Pu(OH)4, orAm(OH)3.
The term 'eigencolloid' or 'intrinsic colloid', is often used in distinction to apseudocolloid. A pseudocolloid is one in which elements (colloids orcations) become adsorbed onto pre-existinggroundwater colloids due to their affinity to these colloids or to thehydrophobic properties of the dispersing medium.[2]
Inenvironmental chemistry, enhanced migration of heavy metal and radioactive metal contaminants in ground and surface waters is often facilitated by eigencolloid formation.
Eigencolloid formation occurs readily ingroundwater upon storage ofradioactive waste.Colloid-facilitated transport is a mechanism responsible for the mobilisation ofradionuclides into the widerenvironment, causing radioactive contamination. This is apublic health concern since elevated radioactivity in the environment ismutagenic and can lead tocancer.
Eigencolloids have been implicated in the long-range transport ofplutonium on theNevada Test Site.