Abstract
Electrolytic reduction of Tc (VII) in a nitric acid solution was examined to recover Tc as well as rare metals (Pd, Ru, and Rh) by an electrolytic extraction method, i. e. electro-reductive deposition, from a spent fuel solution for future nuclear fuel reprocessing. An absorption peak at 482 nm observed after electrolytic reduction of Tc (VII) in 3 M HNO3 at -0.3 and -1.0V vs SSE (standard silver electrode) suggests the reduction of Tc (VII) to Tc (IV). When Pd is present together with Tc in 1 M HNO3, the concentration of Tc decreased to 85% of the initial concentration by electrolysis at ±0.0 V vs. SSE for 60 min, suggesting acceleration of Tc deposition by Pd (promoter effect). The Tc concentration, however, increased returning to the initial value after further electrolysis. The Pd deposit from Tc-Pd-Ru-Rh solution redissolved more easily than that from Pd-Ru-Rh, as a consequence of a change in the oxidation-reduction property of the Pd deposit due to the presence of Tc in the solution.
