An electrochemical pCl-stat was devised to determine the stability constants of UO
2Cl
+ and UO
2NO
3+ ion complexes in the aqueous solutions of KNO
3 and NaNO
3-NaClO
4 containing minor amounts of Cl
- ion at 25°C.
The stability constant Kc of UO
2Cl
+ at various ionic strengths μ was estimated from the amount of UO
2Cl
+ ion obtained by the integration of the current-time curve of the pCl-stat following the additon of a given amount of uranyl salt. As previous investigators have pointed out, the stability constant at higher ionic strengths is relatively small, e.g., Kc=2.42, 1.40 and 0.89 at μ=0.54, 0.82 and 1.06, respectively. However, the thermodynamic stability constant Ka at μ=0 obtained by extrapolation of the curve of Kc against μ, resulted in the remarkably high value of 15.
The stability constants of UO
2NO
3+ were also determined by measuring the Kc values of UO
2Cl
+ as a function of compositions at constant μ in mixed solutions of NaNO
3 and NaClO
4. The observed results were 0.37, 0.20 and 0.19 at μ=0.54, 0.82 and 1.06, respectively.
抄録全体を表示