Chemical study on the separation and purification of promethium-147
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A chemical process for the separation of147Nd/147Pm from fission products of synthetic radioactive waste solution has been developed. The process includes: (1) denitration, (2) removal of high concentration of uranium by 30% TBP/kerosene extraction, (3) removal of95Nb,103Ru,137Cs and part of90Sr by 50% TBP/dodecane extraction, (4) separation of147Nd/147Pm from part of90Sr and95Zr by oxalic acid precipitation, and (5) removal of144Ce by mixture of 0.4M D2EHPA and 0.2M TBP extraction. Experimental results indicate that the recovery of147Nd/147Pm in the final separated solution is about 90%. The purification of147Nd and147Pm from some other rare earth elements, viz.153Sm,154Eu and144Ce was further investigated by using a Dowex 50W×8 ion-exchanger. Parameters of flow rate, eluent concentration and pH were examined. The results show that the recovery and radionuclide purity of147Nd plus147Pm under the present separation conditions are 77.8% and 98.6% for diethylenetriaminepentaacetic acid (DTPA) and 87.3% and 99.5% for nitrilotriacetic acid (NTA), respectively.
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