Discussions


The oxidation process:

  • At the beginning the Eu was 3+ (Eu III sulfate octahydrate)

  • After heating at 300 °C, the water was remove from the crystal.

  • At the beginning of the experiment we had Eu2(SO4)3 powder without water

  • In the oxidation phase the Eu2(SO4)3 powder tend to form again the hydrate sulfate and an oxide was form on the surface of the electrode and passivate the surface.

  • The current was very small in the oxidation phase => an oxide cover the surface and no PbSO4 crystals was formed on the surface (in the observation area).

The reduction process:

  • The peak in the reduction phase can be the reduction of the Eu3+ to Eu2+

  • Eu (III) has the highest standard redox potential, whitch makes possible its selective reduction [1]:


  • The chemical properties of E(II) are similar to those of the alkaline earth ions [2]

Possible candidate

The electronic configuration of Eu (63) is similar to Ba (56)

[Xe].6s2
 [Xe].4f7.6s2







  • EuSO4 is insoluble in water

  • Difficult to obtain

  • Expensive

[1]
 T. Hirato, H. Kajiyama, H. Majima, Y. Awakura, Electrolytic reduction of Eu (III) to Eu (II) in acidic chloride solutions with titanium cathode. Metall. Mater. Trans. B 26B (1995) 1175-1181.
[2]
 T. Donohue, Photochemical separation of europium from lanthanide mixtures in aqueos solutions. J. Chem. Phys. 67 (11) (1997) 5402-5404.


Conclusions