Maybe the adsorption performance of minor actinides(MAs)is similar to that of REEs, because of the similar chemical properties between these elements.Therefore, it is not necessary to consider the adsorption amounts of MAs.These results suggest that Al ferrocyanide has the selective adsorption performance of PGMs and Mo.Table 2 Composition of simulated HLLW(26 elements)Before AdsorptionAfter AdsorptionConcentration of simulated FP metals |mol/L]Fig.4 Adsorption of simulated HLLW(26 elements)into Al ferrocyanide.SEPARATION OF PGMS AND MOLYBDENUM BY SOLVENT EXTRACTIONIn the former section, we confirmed that the simultaneous adsorption of PGMs and Mo from HLLW was accomplished by Al ferrocyanide.The Al ferrocyanide adsorbing PGMs and Mo is decomposed thermally in air.The residue is washed by HNO3 solution and PGMs and Mo are leached to the HNO3 solution.The separation of PGMs and Mo in the leachate was tested by solvent extraction technique.The practical separation of Mo has already been studied by a typical acidic phosphorus compound, D2EHPA(di-2-ethylheylphosphorus acid).Morita et al. tested the extraction separation of Mo from Zr, Y, Pd and Nd and succeeded the separation of Mo and Zr from other metals(7).However, a new process study is required for the separation of PGMs in HNO3 solution.We selected some extractants containing nitrogen donors and sulfur donors, DOA(Di-n-octylamine), TMOEAA(Tris(N-methyl-N- octylethylamide)amine), MOTDGA(N,N’-dimethyl-N,N’- di-n-octylthiodiglycolamide)and DHS(Di-n-hexylsulfide), which promise to extract PGMs effectively.Fig.5 shows the chemical structures of used extractants.DHS Di-n-hexyl-sulfideDOA Di-n-octyl-amineTMOEAA Tris(N-methyl-IM-octyl-ethylamide)amineMOTDGA N,N'-dimethyl-W,A/’-di-n-octyl-thiodiglycolamideFig.5 Chemical structures of used extractants.Palladium nitrate, Rhodium nitrate and Ruthenium nitrosyl nitrate were dissolved in 1mol/L HNO3 solution.The concentration of HNO3 was adjusted in the range of 1 to 7 M and the concentrations of Pd, Rh and Ru to 100 μg/g(about 10-3 mol/L), respectively.After the pre- equilibrium using HNO3 solution, CCl3H solutions dissolving these extractants(0.5 mol/L)were in contact with the PGM solution in a vial, which was shaken at room temperature for 60 min. A small amount of the aqueous solution was sampled and the concentrations of PGMs were measured by ICP.Fig.6 shows the extraction of PGMs with DOA.DOA extracted Pd in low HNO3 concentration range; however did not extract Ru and Rh.MOTDGA and TMOEAA extracted Pd completely.However, Ru was not extracted effectively and Rh was not extracted at all.Rh ion in HNO3 solution does not form anion complexes even in high concentration range of HNO3.Cation complexes such as Rh(H2O)63+, Rh(H2O)5(NO3)2+, may be formed.