痕量单一价态钚溶液的制备

Preparation of Trace Single Oxidation State Plutonium Solutions

摘要: 建立了痕量Pu(Ⅳ)、Pu(Ⅴ)、Pu(Ⅵ)溶液的制备方法，并跟踪了各价态钚溶液的稳定性。采用TTA选择性萃取Pu(Ⅳ)、HDEHP萃取Pu(Ⅳ+Ⅵ)的方法分析了溶液中钚价态的分布。结果表明，将浓度为10^-11mol/L量级的钚溶液在1 mol/L HNO₃体系中反复蒸干可制得Pu(Ⅳ)溶液；Pu(Ⅳ)在0.5~1 mol/L HNO₃ 0.1 mmol/L KMnO₄溶液体系中反应24h，可获得Pu(Ⅵ)溶液；Pu(Ⅵ)避光保存5d后，可得到Pu(Ⅴ)溶液，各单一价态钚溶液的纯度均大于90%。在pH=3.0、0.01 mol/L NaCl体系中，各价态均不能稳定存在，因此，所需单一价态钚溶液应新鲜制备。

Abstract: The trace levels of single oxidation state plutonium(Pu(Ⅳ,Ⅴ,Ⅵ)) solution was prepared, and the stability was monitored over time. The oxidation state distribution of the solution was analyzed by solvent extraction methods, in which Pu(Ⅳ) was extracted with TTA and Pu(Ⅳ+Ⅵ) was separated by HDEHP. The Pu(Ⅳ) solution is prepared by heating the solution until dryness in 1 mol/L HNO₃ repeatedly, and Pu(Ⅵ) solution is obtained by keeping Pu(Ⅳ) in 0.5-1 mol/L HNO₃-0.1 mmol/L KMnO₄ system for 24 h. Pu(Ⅵ) is reduced automatically to Pu(Ⅴ) in the dark for 5 d. All of these single plutonium solutions could not keep steady in pH=3.0, 0.01 mol/L NaCl system. Consequently, single oxidation state plutonium solutions need to be prepared freshly for each experiment.