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)}
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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)}.