X射线吸收精细结构技术在放射性核素界面反应中的应用

Application of XAFS Technique in Interface Interaction Study of Radionuclides in Environment

X射线吸收精细结构（X-ray absorption fine structure,XAFS）技术是同步辐射应用的一个最重要方向之一,XAFS技术可以原位探测中心原子的2—3个邻近配位壳层,获得中心原子的电子结构和微观化学结构信息,已成为微观领域最重要的结构分析工具。在环境科学领域,XAFS技术可以在分子水平上研究污染物尤其是金属离子在天然颗粒物、土壤、沉积物、植物组织以及生物体等环境界面反应的微观结构和反应机制,揭示金属离子在环境界面发生物理化学反应的价态变化规律、电子结构变化规律以及化学形态变化规律等重要科学问题,丰富我们对元素的重要化学性质和反应过程的认识。本文简要介绍了XAFS的基本原理,重点综述了应用XAFS技术探讨矿物、腐殖质、植物组织和微生物等对放射性核素界面反应机理的主要研究进展,并对XAFS技术在多相体系对放射性核素的界面反应、生物体对放射性核素的耐毒机理等方面的可能应用进行了展望,以期为放射性核素环境污染的修复和治理提供技术帮助和支持。

X-ray absorption fine structure（XAFS） technique is one of the most important methods for the application of synchrotron radiation technique,and it can be used to study the interaction mechanisms of radionuclides or heavy metal ions and their microscopic structures at molecular level on natural particles,soils,sediments and organisms,providing experimental evidences for elucidating the binding mechanisms of radionuclides or heavy metal ions on solid surfaces.It has also been demonstrated that X-ray absorption fine structure（XAFS） technique can be used to distinguish different sorption mechanisms on surfaces when they are occurring simultaneously.In this paper,the advances in the application of X-ray absorption fine structure（XAFS） technique on the interaction mechanism investigations of radionuclides on minerals,humic substances（such as humic acid（HA） and fulvic acid（FA））,plant tissues and microorganisms are reviewed,and the potential applications of X-ray absorption fine structure（XAFS） technique in the studies on the interfacial interactions of radionuclides in heterogeneous systems and the mechanisms of biological tolerance to heavy metals are also discussed,so as to provide the fundamental data for the treatment and remediation of toxic metal-polluted environments.The information presented in this study will also allow scientists and engineers to develop better models that predict the interaction of radionuclides or heavy metal ions with solid surfaces.