Lanthanide fluoride coprecipitation

Eermium coprecipitates with lanthanide fluorides and hydroxides, showing it to form lanthanide-like Em + ions. These elute from cation-exchange resins slightly before Es +, whilst its chloride and thiocyanate complexes are eluted from anionic exchange resins just... 

Analytical methods based on coprecipitation techniques are used to determine the oxidation-state speciation of the light actinides, which can occur in solution in multiple oxidation states. An example of such a separation is the ability to selectively remove tri-and tetravalent actinide cations from penta- and hexavalent species by coprecipitation with lanthanide fluoride (Choppin 1985). Lanthanide fluoride eoprecipitation has been used to perform oxidation-state identification in ground-water samples (e.g., Nash et al. 1988). There are numerous other examples of the application of the coprecipitation technique to environmental samples. 

Calcium fluoride will coprecipitate most actinides and lanthanides, but few other elements. The lanthanide elements will separate with the transplutonium fraction. The concentration of the lanthanides in environmental water is at the sub-microgram per liter level (2). The mass of lanthanide elements electrodeposited from a typical sample does not interfere with alpha spectrometric energy resolution. Although rare earth... 

In the processing of nuclear materials, precipitation/coprecipitation techniques are used for the separation of the actinides from most fission products. Both fluoride and oxalate complexes of these metal ions are sufficiently insoluble to accomplish this separation (Stary 1966). Coprecipitation with bismuth phosphate has also been used for this purpose (Stary 1966). Because of their insensitivity to subtle changes induced by minor cation-radius changes, such techniques are not useful for the separation of the lanthanides from the trivalent actinide metal ions. 

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