ИСТИНА

Electrochemical methods in radiochemistry have great potential for practical and fundamental applications. They allow minimizing the generation of new or additional radioactive wastes and in most cases do not require new reagents [1]. Electrochemical behavior of Тс and Mo compounds in alkaline and neutral media was studied [2, 3]. The process of reduction of these metals to metallic state is still not evident. In the process of electrolysis of solutions, dense layers of oxides Mo (IV) and Tc (IV) are formed on the cathode. In [4], it was shown that the reduction of molybdenum compounds in the presence of high concentrations of the acetate anion leads to the formation of precipitates containing metallic molybdenum on the cathode. Apparently, complexation allows to inhibit the processes of disproportionation and the formation of insoluble precipitates. Polarographic studies of molybdenum compounds showed a stepwise reduction mechanism according to the Mo (VI) → Mo (V) → Mo (III) scheme; the last wave of reduction of the formed Mo (III) compounds to the metal is not fixed on the polarograms, which is explained by the occurrence of a parallel hydrogen evolution reaction. The similarity of the electrochemical behavior of the compounds Mo (VI) and Tc (VII) suggested that in the process of electrolysis of an electrolyte containing high concentrations of ligands (acetates, citrates) it is possible to detect a metallic phase at the cathode. Polarographic studies of solutions containing ammonium pertechnetate and high concentrations of acetate anions showed a stepwise reduction of Tc (VII) → Tc (V) → Tc (IV) → Tc (0); the last wave is fixed at Е1 / 2 > -1250 mV (vs SSE). The obtained X-ray amorphous coatings were examined using EXAFSXANES spectroscopy. A predominantly metallic phase is present in the sediments and a small amount of Tc (IV) oxide. The designed electrodeposition method applying the new electrolytes with pH ≈ 7 allowed us to electroplate thin layers of Tc-containing films on aluminum substrate surface that was earlier considered impossible. The elaborated electrochemical method was characterized with the precise current densities and chemical composition of new electrolyte type. Its application allows the electrochemical separation and concentration of molybdenum and technetium separately or in its mixture. The results presented in [4] show that electrochemical deposition from the proposed electrolyte is possible only for the highest degree of oxidation of molybdenum. For technetium, the same pattern