层状金属硫化物对放射性核素U(VI)和Sr(II)的高效选择性吸附及机理研究

With the peaceful utilization of nuclear energy and the rapid development of nuclear industry, the radioactive strontium from byproduct of uranium fission makes them harmful to human life and the environment. The selective removal of these radionuclides in the presence of high salt concentrations from industrial nuclear waste is necessary for safe storage. Numerous studies have shown that layered metal sulfides have exceptionally selective for radionuclides removal. However, the interaction mechanism is unclear. In this project, the sequestration of U(VI) and Sr(II) on previous as-prepared layered metal sulfides NaInS2 were systematically investigated using batch experiments. The family of robust layered metal sulfides contains highly mobile alkaline ions in their interlayer space, which are easily exchangeable with other radioactive cations. Based on the adsorption kinetics and thermodynamic model, the interaction mechanism of layered metal sulfides with target ions were studied by various microscopic characterization including XRD, XPS and EXAFS techniques. The result is expected to provide evidence for the development of a novel layered material and have potential application in radioactive ions contaminated wastewater remediation.

随着核能的利用和快速发展，在这个过程中产生的放射性铀以及其裂变产物锶会对人类和周围的环境产生危害。在工业核废水中，能够在高浓度盐溶液中选择性吸附这些放射性核素是安全处置过程中必不可少的。大量研究表明层状金属硫化物材料对放射性核素有着高效的吸附性能，但机理尚不明确。在本项目中，利用前期合成的层状金属硫化物NaInS2展开对放射性核素U(VI)和Sr(II)去除研究。这一类层状金属硫化合物因其层间含有大量可交换的碱金属离子而应用于放射性离子的去除。为了评估其吸附性质，我们采用批示实验系统的研究了U(VI)和Sr(II)在层状金属硫化物上的吸附行为。基于吸附动力学和热力学模型，我们利用各种微观表征技术(包括XRD，XPS和EXAFS技术)，从分子水平上探究了层状金属硫化合物与放射性目标离子的相互作用机制。本项目预期研究成果为放射性核素的有效去除提供一种新型层状材料，对放射性核素污染治理有重要应用

层状金属硫化合物因对软金属离子具有高效吸附能力和选择性吸附特性，对评估放射性核素在环境中迁移和转化的具有重要意义。本项目探索了一系列层状金属硫化物纳米材料的构筑方法，搭建层状金属硫化物的晶体结构，利用静态批示实验和先进的光谱表征技术分析了放射性离子在层状金属硫化物上的吸附形态和作用机理，采用EXAFS技术研究U(VI)在层状金属硫化物上的化学形态和微观结构，结合密度泛函(DFT)理论计算进一步得到U(VI)与层状金属硫化物的结合形式及吸附能等信息，阐明层状金属硫化物的晶体参数和表面吸附模型，研究结果对放射性核素在金属硫化物的环境行为具有重要科学指导意义。