Development of an automated batch-type solid-liquid extraction apparatus and extraction of Zr, Hf, and Th by triisooctylamine from HCl solutions for chemistry of element 104, Rf

Abstract

Solid-liquid extraction of the group 4 elements Zr and Hf, which are homologues of Rf ( = 104), and Th, a pseudo homologue, by triisooctylamine (TIOA) from HCl solutions was performed by batch method. After examining the time required to reach extraction equilibrium for these elements in various concentrations of TIOA and HCl, we investigated in detail variations in the distribution coefficients ( d ) with TIOA and HCl concentrations. The d values of Zr and Hf increased with increasing the HCl and TIOA concentrations, suggesting an increase in the abundance of the anionic chloride complexes of Zr and Hf. On the other hand, the d values of Th were low in all the HCl concentrations studied, implying that Th does not form anionic species dominantly. We developed a new automated batch-type solid-liquid extraction apparatus for repetitive experiments on transactinide elements. Using this apparatus, we performed solid-liquid extraction employing the radioactive nuclides 89m Zr and 175 Hf produced by nuclear reactions and transported continuously from the nuclear reaction chamber by the He/KCl gas-jet system. It was found that the distribution behaviors in 7-11 M HCl are almost constant in the time range 10-120 s, and the d values are consistent with those obtained in the above manual experiment. This result suggests that the chemical reactions in the extraction process reach equilibrium within 10 s for Zr and Hf under the present experimental conditions. It took about 35 s for the extraction using the apparatus. These results indicate the applicability of the present extraction using the developed apparatus to 261 Rf ( 1/2 = 68 s) experiments.

Development of new methods for aqueous chemistry on element 104, rutherfordium: Batchtype solid-liquid extraction and coprecipitation

“…The chemical reactions were found to be fast in the TIOA/HCl extraction when using TIOA resins with weight concentrations above 30 wt%. 4 The dependences of the K d values of Zr, Hf, and Th on the HCl concentration are shown in Figure 1 together with the results obtained in the online experiment. The results indicate that the abundances of the anionic chloride complexes of Zr and Hf increase with higher HCl concentrations, and that these complexes assemble with protonated TIOA ions as (R 3 NH) 2 [MCl 6 ] to be extracted into the solid phase, 26 while the species of the pseudo homologue Th dominantly exist in HCl solutions.…”

“…Schematic diagram of the online extraction experiment using the batch-type solid-liquid extraction apparatus AMBER. 4 The nuclear reaction products are continuously transported to the dissolution equipment in AMBER located in chemistry room. Eluate from the dissolution equipment goes through two passage valves and a slider-type valve into a chemical reaction container.…”

“…Thus, it is difficult to clarify various chemical properties of SHEs. In this paper, two types of newly developed experimental methods to study chemical properties of SHEs are presented; one is the method to study time dependence of the solid-liquid extraction behavior (observation of the equilibrium of the chemical reactions) for SHEs, 4 and the other is that to study coprecipitation behaviors of SHEs with Sm hydroxide. 5,6 In solution chemistry for SHEs, extraction behaviors to solid phase or organic solution have been mainly investigated on the lightest transactinide elements, rutherfordium (Rf, Z = 104) and dubnium (Db, Z = 105).…”

“…The K d values of Zr (circles) and Hf (squares) obtained by online experiment with AMBER as a function of HCl concentration at 31 wt% of the TIOA resin and those obtained in offline batch experiments with 10-min shaking (double circles and squares) together with the K d values of Th (double triangles) 4. …”

Solvent Extraction of Zirconium and Hafnium as Homologues of Rutherfordium by Triisooctylamine from HCl Solutions

“…After the production, the product nuclides were purified by anion-exchange method. The procedures in these production and purification are described in the literature [15]. The purified Zr and Hf tracers were mixed and stored in 6 M HCl solutions in a polypropylene (PP) tube.…”