Ion-exchange behavior of Zr and Hf as homologues of element 104, Rf, in H2SO4 and H2SO4/HClO4 mixed solutions

The ion-exchange behavior of Zr and Hf in H2SO4 and H2SO4/HClO4 mixed solutions has been studied by a batch method using the carrier-free radiotracers 88Zr and 175Hf. It is found that the ion-exchange behavior of Zr and Hf is basically similar to each other, and that Zr and Hf are adsorbed on the cation-exchange resin as well as on an anion-exchange one in H2SO4. In 0.11-0.99 M H2SO4, the logarithmic values of distribution coefficients (Kd) of Zr and Hf on the cation- and anion-exchange resins linearly decrease with log[H+]eq and log[HSO4-]eq, respectively, indicating that M44 and M(SO4)32- (M=Zr and Hf) are the predominant cationic and anionic species adsorbed on the resins, respectively. The Kd values of Zr and Hf on the cation-exchange resin in H2SO4/HClO4 at [H+]eq = 1.0 M also decrease with an increase of [HSO4-]eq, reflecting successive formation of sulfate complexes. The slope analysis demonstrates that Zr and Hf are coordinated by one SO42- ion at 0.011 and 0.020 M [HSO4-]eq, respectively, and by two SO42- ions at 0.079 and 0.20 M [HSO4-]eq, respectively. (orig.)