Adsorption Behavior of ~(95)Nb and ~(179)Ta as Homologues of Element 105, Db, on Cation Exchanger in HF/HNO_3 Solution

摘要

Adsorption behavior of the group-5 elements, ~(95)Nb and ~(179)Ta, on cation-exchange resin was studied in mixed solution of HF and HNO_3 (HF/HNO_3) as a model experiment of their heavier homologue, element 105 (dubnium, Db). Chemical reactions of these elements in the cation exchange rapidly reached the equilibrium. It was found that distribution coefficients of Nb and Ta decrease with increasing the fluoride ion concentration in the studied range of 10~(-7)-10~(-5) M. Clear difference between Nb and Ta was observed in the variations of the distribution coefficients against the fluoride ion concentration. This would originate from their different chemical species of fluoride complexes. We propose the cation-exchange experiment of Db based on the present experimental results to understand its fluoride complex formation.