U(Ⅵ)电还原反萃动力学研究——Ⅱ.U(Ⅵ)反萃和U(Ⅳ)萃取动力学

本文在带有阴阳极的恒界面池中研究了HNO_3-N_2H_5NO_3(H_2O)/UO_2(NO_3)_2-HNO_3(30％TBP-煤油)体系在U(Ⅵ)电解还原过程中的U(Ⅵ)反萃和U(Ⅳ)萃取动力学。这是U(Ⅵ)电还原反萃动力学研究的第二步。根据实验结果和数据处理,得到U(Ⅵ)反萃和U(Ⅳ)萃取过程的表观活化能分别为36.02kJ/mol和21.13kJ/mol;U(Ⅵ)反萃和U(Ⅳ)萃取速率随两相搅拌速率的增大而增大;U(Ⅵ)反萃和U(Ⅳ)萃取过程均由扩散控制。随着阴极电位的降低,U(Ⅵ)反萃和U(Ⅳ)萃取速率均增大。

STUDIES ON THE KINETICS OF URANIUM ( VI ) ELECTRO- REDUCTION AND REEXTRACTION I . KINETICS OF U( VI ) REEXTRACTION AND U( IV ) EXTRACTION

The kinetics of U( VI ) reextraction and U( IV ) extraction in the process of U( VI ) electro-reduction with the system of HNO3-N2H5NO3(H2O)/UO2(NO3)2-HNO3(30% TBP-OK) is investigated with a constant interfacial area cell (Lewis cell) with cathode and anode in it. According to the experimental results and data processing, the apparent activation energy of the U( VI ) reextraction process is 36. 02 kJ/mol. The U( VI ) reextraction rate increases when the stirring speed of two phases increases. This process is mainly diffusion controlled. For the U (IV ) extraction process, the apparent activation energy is 21.13 kJ/mol. The U( IV ) extraction rate also increases when the stirring speed of two phases increases. This process is mainly diffusion controlled. The lower the potential of cathode is, the higher are the rates of U( VI) reextraction and U( IV ) extraction.