Photochemical techniques are used for the mutual separation of lanthanide elements. By emitting tight from an ultrahigh-pressure mercury lamp to a nitric acid solution that contains fourfold mixtures of lanthanide elements (neodymium, samarium, europium, and gadolinium), (NH4)(2)SO4, and isopropyl formate, neodymium, samarium, and europium are photoreduced and form Ln(2+) sulfates, while gadolinium is not photoreduced and does not coprecipitate. When lanthanum is introduced instead of gadolinium, lanthanum coprecipitates along with neodymium, samarium, and europium. These results are explained by photolyzing Nd-Gd and Nd-La systems for comparison, and the difference in precipitation behaviors between these two systems is explained by the differences in ion size of these elements. Photolysis is also performed for a Nd-Am system. Am3(+) is carried along with neodymium and coprecipitated. As a way to decrease the amount of americium carried along with neodymium, americium is photochemically oxidized by emitting light from a deuterium lamp as well as from a mercury lamp. The fraction of americium carried with neodymium decreases with the use of this technique. This result is also explained by the differences in ion size of these elements. References: 12
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