高效快速去除环境中放射性核素铀(U)和锝(Tc)的机理研究

Environmental radioactive contamination is one of the most important problems that must be solved for applications of nuclear technology. Uranium (U) and technetium(Tc) are multivalent radioactive elements and can easily migrate in the aquaticenvironment, resulting in serious environmental damages. Nano zero-valent iron(nZVI) has attracted much attention in pollution control and environmenta lremediation due to its excellent surface sorptive capacity and chemical reactivity. Using the plasma sputtering technology, this project aims to construct novel reactive composite materials that are capable of effectivelysequester and reduce radioactive contaminants from the solution by adjustingthe parameters of the sputtering process, optimizing the surface loading of nZVI on clay minerals, and achieving performance stability of composite materials. U (VI)and Tc (VII) are selected as target radioactive elements. Batch experiments,surface characterization, and computational calculations will be carried out to further elucidate the synergistic reaction mechanism between clay mineral and nZVI in sorption and reduction of multivalent radioactive contaminants. To evaluate the feasibility of our proposed method inreducing radioactive contamination, we propose to use alpha and beta particle detectors to quantify the changes of radiation in experimental samples before and after the treatment. The results of this study will provide a novel technology to effectively remediate environmental radioactive contamination with theoretical support on a molecular level.

环境放射性污染是核利用中必须解决的重要问题之一。铀(U)和锝(Tc)是多价态的放射性元素，易在水环境中迁移造成严重的环境危害。固体负载纳米零价铁表现出良好的表面吸附能力和化学反应活性，在污染治理和修复中引起了极大的关注。本项目以 U(VI) 和Tc(VII)为放射性目标元素，采用等离子体溅射技术，通过调节溅射工艺参数，在粘土矿物表面上负载纳米零价铁，可控构筑性能稳定的粘土矿物/纳米零价铁复合材料，研究该复合材料在溶液条件下对多价态放射性元素吸附与还原去除的强化效果；采用静态批实验、微观表征和理论计算相结合，阐述该复合材料对多价态放射性元素吸附与还原的协同去除机理。拟利用α和β粒子探测器，检测实验样品被处理前后的放射性变化，验证上述物理化学方法的可行性；研究结果将为放射性核素的有效去除提供一种新技术，为环境放射性污染治理提供理论支撑

放射性核素现已广泛应用于能源、农业、科研、医学、国防等多个领域。在巨大的利益面前，如何治理伴随而来的放射性废水来保障放射性核素的安全使用也越来越受到人们的重视。铀和锝是两个多价态放射性元素，其去除机理有别于其它放射性元素，需要特别关注。本项目采用等离子体溅射和化学原位还原沉积法可控构筑了粘土矿物/纳米零价铁复合材料，既解决了纳米零价铁容易团聚的问题，又利用了黏土矿物对放射性核素良好的吸附能力，实现了优势互补。采用宏观批实验和微观表征相结合的方法，研究了不同实验条件对粘土矿物/纳米零价铁复合材料吸附和还原铀和锝的影响，揭示了该复合材料对铀和锝吸附与还原的协同去除机理。为了提高载体的性能，进一步开发了氨基化生物炭/尖晶石、纤维素纳米纤维和金属有机框架等新型功能材料；为了提高还原能力，制备了新型光催化剂，并评估了其光电性能。研究表明粘土矿物/纳米零价铁复合材料对铀和锝有良好的吸附、还原协同去除能力，在多价态放射性核素污染水体的治理中有良好的应用前景。