硝酸铀酰-硝酸-磷酸三丁酯体系的反萃取动力学研究

Kinetic Studies on the Stripping of Uranyl Nitrate in TBP-HNO_3 System

本文采用恒界面池法和上升单液滴法研究了UO_2(NO_3)_2/HNO_3/TBP-环己烷体系的反萃取动力学。得出扩散控制下的反萃速率方程为R=k_1[U]_(O)[TBP]_(O)^(-1.17)[HNO_3]^(-1.70;在恒定硝酸浓度下化学反应控制的反萃速率方程为R=k_2[U]_(O)[TBP]_(O)~0,并对二种速控类型下的反萃机制进行了讨论。

The kinetics of the stripping of UO2(NO3)2 in tri-n-butyl phosphate(TBP)-cyclohex-ane with nitric acid solution has been investigated by using constant-interface cell and single drop technique. Under the conditions of the constant-interface cell method, the rate of stripping of uranium (VI) increased steadily with the stirring speed and was nearly independent of temperature. The rate equation was R = k1[U](o)[TBP](o)-1.17[HNO3]-1.70. The rate of stripping might be controlled by the diffusion process of complex UO2(NO3)2· 2TBP from the organic, phase to the interface. In the case of single drop method, the rate of stripping of uranium ( VI ) increased with increasing temperature and the apparent activation energy was found to be 27. 8 kJ/mol. The rate equation was R = k2[U](o)[TBP](o) in 3 mol/L HNO3. It is suggested that the rate-controlling step might be the dissociation reaction of the complex UO2(NO3)2 · 2TBP at the interface.