Isocratic anion exchange separations of Group V elements

Procedures for Db chemical characterization in off-line experiments

“…The procedure used for isolation of niobium and tantalum from the irradiated Hf foil was based on the results reported in Ref. [18]. Figure 2 shows that in the 6 M HF/4 M HCl medium isocratic separation of Hf, Re, and Nb was successfully achieved and was in good agreement with the data reported in Refs.…”

“…In order to obtain a large total efficiency for an experiment the separation factor between Group IV and V elements must be as high as possible while minimizing the volume of each fraction in order to facilitate the fast preparation of a counting sample. Based on reported data of distribution coefficients (K d ) [18,22] for the elements mentioned above in HF/HNO 3 media, the 11 M HF/7.7 M HNO 3 matrix was chosen to achieve the goal of separating the Group IV elements from a combined Nb and Ta fraction. Under these conditions the K d values of Nb and Ta are relatively small and close to each other, which allows them to be eluted together in a small fractional volume.…”

Discovery of the elements with atomic numbers Z = 113, 115 and 117 (IUPAC Technical Report)

“…Wilk et al [35] sought to improve the separation scheme employed by Stoyer et al [26] and encountered Nb and Ta both evincing two behaviors which could not be explained although the authors did suspect that this was evidence for different speciation of both the Nb and Ta in the solutions employed. The existence of a variety of halide, oxyhalide, and hydroxyhalide forms for the heavy Group 5 elements has been acknowledged as a complicating factor in their chemistries [36][37][38]. The chemistry employed in the Z = 115 studies seeking to prove the identity of dubnium did not employ the same steps as in the definitive studies on the short-lived 113 from the 2n evaporation channel and subsequently a total of four inclusive chains from the 2n evaporation channel were found in 2013 [21].…”