Speciation of Tracer Amount Metals at Solid-Liquid Interface by use of Quantum Beam

有证据表明，释放到地圈中的许多放射性核素以胶体粒子的形式存在，这些粒子可能会保持悬浮状态，从溶液中沉淀出来，然后随着条件的变化而固化。本文研究了铀(VI)在银和金胶体颗粒上的吸附。铀酰物种在核废物库中的化学行为是人们非常感兴趣的，因为在直接处置乏燃料的情况下，铀是主要成分，它控制着乏燃料本身的长期释放。我们测量了U(VI)离子负载的银和金胶体粒子在水悬浮液的大pH范围内的拉曼光谱。观察到UO_2~(2+)&Lt；~(2+)&Gt~(2+)离子吸附到银胶粒子上后，其拉曼活性对称伸缩频率向较小的波数移动，且这种移动与悬浮液的pH有关。这一观察结果否认了U(VI)在银胶粒子上吸附后全部释放的情况，但在金胶粒子的实验中，拉曼光谱并没有扩展到pH依赖性，从而证实了U(VI)在金胶粒上的吸附后所有配体都被释放的观点。

There is an evidence that much of the radionuclides released into the geosphere exist as colloidal particles that may remain suspended, settle out of solution, and solidify with changes in condition. This report focuses on the adsorption of uranium (VI) on silver and gold colloidal particles. The chemical behavior of uranyl species in a nuclear waste repository is of considerable interest because in the case of direct disposal of the spent fuel, uranium is the main component and it governs the long-term release of radionuclides from spent fuel itself.We made measurements of Raman spectra of U (VI) ions loaded silver and gold colloidal particles for wide range of pH of the aqueous suspension. It was observed that Raman active symmetric stretching frequency of UO_2^<2+> ion shifts to smaller wavenumber when adsorbed onto silver colloidal particle, and that the shift depends on the pH of the suspension. This observation discounts the case that all U (VI) ligands are released following the adsorption onto silver colloidal particle.However, the Raman spectra did not extend pH dependency in the experiments of gold colloidal particles, thus the idea that all ligands are released following the adsorption was confirmed for U (VI) adsorption onto gold colloids.