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，它们可能会随着环境的变化而保持悬浮状态，沉淀出溶液并固化。本文主要研究了铀（VI）在银和金胶体颗粒上的吸附。核废料储存库中铀基物种的化学行为引起相当大的兴趣，因为在直接处置乏燃料的情况下，铀是主要成分，它支配着乏燃料本身的放射性核素的长期释放。在不同pH值的水溶液悬浮液中，对U （VI）离子负载银和金胶体粒子的拉曼光谱进行了测量。观察到UO_2^<2+ b>离子吸附在银胶体颗粒上时，拉曼主动对称拉伸频率向较小的波数偏移，且偏移与悬浮液的pH值有关。这一观察否定了所有U （VI）配体在吸附到银胶体颗粒上后释放的情况。然而，在金胶体颗粒的实验中，拉曼光谱并没有扩展pH依赖性，从而证实了吸附U （VI）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.