Description
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Gadolinium is a lanthanide that has a bright, reflective, silvery white appearance in its natural solid state. It is stable in dry air but will tarnish in moist air; it also reacts slowly with water. Gadolinium has an atomic weight of 157.25, a melting point of 2394 °F, and a boiling point of 5923 °F. Some common uses of gadolinium include: as a component in microwaves, as a burnable poison in nuclear marine propulsion, to improve the workability of some metals, and in MRI and x-ray imaging.
Isolation
Gadolinium does not occur free in nature, but is found in most minerals which also contain other lanthanides. Extraction processes can be used to isolate gadolinium from these minerals.
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The extraction and isolation processes of gadolinium are very complex. Gadolinium occurs in minerals such as monazite and bastnasite with other lanthanides that have similar chemical characteristics. The complex steps that must be used to separate these lanthanides is never performed on a small scale laboratory basis as it is just too difficult.
The isolation process of gadolinium involves treating the minerals it occurs in with sulfuric acid, hydrochloric acid, and sodium hydroxide. This process separates out the lanthanides from the minerals in their salt forms. Repeated solvent extractions and ion exchange chromatography are used to further separate the lanthanides from each other. Once gadolinium is reduced to its fluoride form, it can be reduced further by reacting it with pure calcium metal under heated conditions. Excess calcium that remains with the gadolinium is removed through vacuum processes yielding pure gadolinium. Gadolinium, like most lanthanides, has slightly toxic traits and should be handled with caution.