| 摘要 |
In removing impurities from acid solutions containing actinides, e.g. U and Th, a complexing agent is added which forms a water soluble complex with the impurities and the difference in molecular size of the ions so produced is utilized to achieve the separation of the impurities and the actinides. For example, the impurities are removed by molecular sieves or electrodialysis. The complexing agents used preferably contain polar group, e.g. hydroxy, ether, ester, keto or carboxy groups and are exemplified by ethylene glycol, 1,3-propane diol, 1,4-butane diol, 1,2,6-hexane triol, polyethylene glycols, ketones of the type R1.CO.R2 wherein R1 and R2 are oxygenated hydrocarbon chains, and nitrogenous derivatives, e.g. hydroxylamine, carbamide triethanol amine, and nitrilo tri-acetic acid. The molecular sieves used are made of acid resistant micro-porous material having a pore size of half the magnitude of the diameter of the complexed actinide molecules but 3-4 times the diameter of the impurity ions, e.g. a siliceous material having a pore diameter between 6 and 12</>rA. Compounds of the type UO2(MO3)n.Lm are produced wherein L is the organic ligand, n is an integer either 1 or 2, and m is an integer either 1 or 2. U.S.A. Specifications 2,717,696 and 2,796,424 are referred to.ALSO:Electrodialysis is used to remove impurities, e.g. fission products, from acid solutions containing actinides, e.g. U, Th and Pu. A complexing agent is added which forms watersoluble complexes with the actinides but not with the impurities. The complexed solution is then placed in the anode compartment of a dialysis cell having a microporous diaphragm with a pore diameter of 6-12</>rA. The fission products migrate to the cathode because of their positive charge, the complex actinide was being retained by the diaphragm because of their larger molecular size. A suitable diaphragm is specified as being prepared from sintered titanium or porous polyethylene. If the complexing of the actinides is carried so far as to produce neutral complexes then a standard diaphragm may be used, or if negative complexes are formed then they are concentrated in the anode space. Suitable complexing agents contain polar groups, e.g. hydroxy, ether, ester, keto, or carboxy groups and many examples are given in the Specification. U.S.A. Specifications 2,717,696 and 2,796,424 are referred to. |
