Pu(OH)4(am)与碳酸根的配位行为研究

为了解在惰气环境Pu(OH)_4(am)与碳酸盐溶液中HCO^-₃，CO^2-₃的配位行为，考察了放置时间对Pu总浓度的影响；同时也考察了pH值、碳酸根总浓度变化对碳酸盐溶液中Pu的主要存在形态及溶解总浓度的影响。实验结果表明，HCO^-₃离子与Pu(OH)_4(am)生成Pu(OH)₄(HCO₃)₂]^2-（lg K=-2.61±0.18, lgβ=54.25±0.18）或Pu(OH)₂(CO₃)₂]^2-（lgK=-2.61±0.18, lgβ=46.91±0.18）；CO^2-₃离子与Pu(OH)_4(am）生成Pu(OH)₄(CO₃)₂]^4-（lgK=-3.52±0.11, lgβ=53.33±0.11）。可能的配位反应方程式为： Pu(OH)_4(am)+2HCO^-₃ = Pu(OH)₄(HCO₃)₂]^2-, Pu(OH)_4(am)+2HCO^-₃ =Pu(OH)₂(CO₃)₂]^2-+2H₂O, Pu(OH)_4(am)+2CO^2-₃=Pu(OH)₄(CO₃)₂]^4-。

Complex Formation of Pu(OH) 4(am) With Carbonate

The complex formation of Pu(OH)_4(am) with carbonate is studied with the variation of pH(8.92~13.08), and the total carbonate concentration range of 10^-4~10^-2 mol/L. The effect of pH value and total carbonate concentration on the dissolved total concentration of Pu(OH)_4(am) and species of Pu in solution are discussed. All experiments were performed in a anaerobic glove box which contained high purity Ar(99.99%), with an oxygen content of less than 5×10^-6mol/mol. The experimental results show that 1∶2 complex of Pu(OH)_4(am) with bicarbonate is obtained and the complex formation constants determined in the experiments. Pu(OH)_4(am)+2HCO^-₃=Pu(OH)₄(HCO₃)₂]^2-， K=10^{(-2.61±0.18)} Pu(OH)_4(am)+2HCO^-₃=Pu(OH)₂(CO₃)₂]^2-+2H₂O， K=10^{(-2.61±0.18)}  At high pHs （10.28~13.08） where carbonate ion is dominant, 1∶2 complex of Pu(OH)_4(am) with carbonate ion is obtained: Pu(OH)_4(am)+2CO^2-₃=Pu(OH)₄(CO₃)₂]^4-， K=10^{(-3.52±0.11)}.