ウランの分離と定量

抄録

U⁶⁺ can be separated from U⁴⁺ as the latter gives precipitate with (NH₄)₂CO₃. Heretofore, the separation of U from Fe is carried out with the use of (NH₄)₂CO₃ or cupferron and this method is to precipitate out the Fe, but it is unsuitable to apply on sample containing large amount of Fe and small amount of U, on the other hand, reduction of Fe³⁺ to Fe²⁺ and U⁶⁺ to U⁴⁺ causes the precipitation of U with (NH₄)₂CO₃ and these are separated each other. In the gravimetric estimation of U by precipitation with the addition of NH₄OH, the formation of precipitate is not possible unless large quantities of NH₄Cl is added, while the formation of precipitate is not possible unless large quantities of NH₄Cl is added, while the formation of precipitate is possible without NH₄Cl when U⁶⁺ is previously reduced to U⁴⁺. Since U⁴⁺ is oxidizable on heating in the presence of air, its titration with KMnO₄ should be carried out below 25°C. Dissolving of U₃O₈ (or 2UO₃·UO₂) in a solution of NH₄VO₃ in H₂SO₄ in the presence of air causes the reduction of V⁵⁺ by U⁴⁺ to V⁴⁺ which is stable in the presence of air and titrable with KMnO₄ solution, therefore, volumetric estimation of U₃O₈ is possible.