协同高效吸附低浓度放射性碘的矿物基Yolk-shell复合微球的构筑与作用机制

Radioactive iodine is one of the most dangerous fission products produced by nuclear accidents. However, high efficient and irreversible adsorption of low-level iodine (I-、I2) from solution is a technical challenge in this field. The project is intends to synthesize mineral yolk-shell composite microspheres based on ship-in-a-bottle method. Low-level iodine is enriched by the shell of microspheres because of the charge characteristics of the amine group, and then the radioactive iodine is chemically adsorbed by the core of microspheres due to the metal/metal oxide. Therefore, the dynamic and efficient adsorption of low-level iodine is obtained through the enrichment of the shell and the consumption of the core. Starting from the structural design of composite materials, the project is mostly centered on the synergy between components of composite microspheres and low-level iodide. By discussing the combined forms, distribution, desorption, transformation and the synergistic reaction mechanism of metal and metal oxides and iodine in the yolk-shell structure of composite microspheres, it will reveal the method and mechanism of control and adjustment of the synthesis of composite microspheres, and the structure-activity relationship between composite microspheres and low-level iodine, and interpret the coordination mechanism of irreversible adsorption of composite microspheres for low-level of iodine. Through the implementation of this project, a novel idea for the irreversible removal of radioactive nuclides with low concentration from effluents will be achieved, which can provide effective technical support for nuclear emergency in our country.

放射性碘是核裂变产生的最具危害性产物之一，而液相低浓度碘（I-、I2）的高效不可逆同步去除是本领域的技术瓶颈。本项目利用“壳内成核”法制备出矿物基Yolk-shell复合微球。借助微球外壳胺基的电荷特性富集低浓度碘，再利用内核金属/金属氧化物化学吸附放射性碘。通过外壳碘的富集和内核碘的消耗，实现对低浓度放射性碘的动态高效吸附。项目从复合材料的结构设计出发，重点围绕低浓度碘与复合微球各组分间的协同作用展开研究。通过探讨金属/金属氧化物、碘在复合微球Yolk-shell结构中的赋存形态、分布状态、脱附与转化行为以及组分间的协同反应机制，揭示材料的合成机理与调控方法以及复合微球微结构与其对低浓度放射性碘吸附性能之间的构效关系，诠释复合微球对低浓度放射性碘的高效吸附机理。通过本项目的实施，为废液中低浓度放射性核素污染物的高效去除提供新思路，也为我国核应急提供有效的技术支撑。

放射性碘是核裂变产生的最具危害性产物之一，吸附容量和吸附效率低、脱附率高、成本昂贵以及多种形态放射性碘（I-、I2）难以同步去除是高效去除放射性碘领域的技术瓶颈。针对上述问题，本研究选用廉价矿物材料凹凸棒石和铜、铋金属制备出多种复合材料，利用物理吸附的碘富集和化学吸附的碘消耗，实现了对低浓度放射性碘的动态高效吸附。系统研究了各复合材料中金属/金属氧化物、碘在结构中的赋存形态、分布状态、脱附及转化行为等，分析了复合材料微结构与其对放射性碘吸附性能之间的构效关系，阐述了复合材料对低浓度放射性碘的高效吸附机理。研究结果表明，纳米铜颗粒负载于凹凸棒石的层间结构中，可使材料展现出较强的抗氧化性且提升吸附后产物的稳定性，产物脱附率低于1%；凹凸棒石基聚合微球，既可借助微球胺基的电荷特性吸附碘离子，又可利用N-Nπ键吸附单质碘，实行了对多形态放射碘的同步去除，同时对10 ppm的低浓度碘吸附效率可达99%以上；分层多孔结构的Cu/Al2O3气凝胶可在宽pH值范围内（3-11）对放射性碘离子具有超高的吸附容量(最高达407.6 mg/g)和快速的吸附平衡时间(约0.5 h)；而铜纳米多孔气凝胶在10 min内可对单质碘拥有1384 mg/g的超高吸附容量，吸附效率接近100%；核壳结构的ZnO@Ag@Cu2O利用化学吸附耦合光氧化机制同步去除多形态放射性碘（I-、I2），且耐强酸碱和重复使用；核壳Bi2S3@ZIF-8纳米复合材料利用ZIF-8的物理吸附和Bi2S3对I2化学吸附生成稳定的BiI3，拥有2627.0 mg/g气态碘和786.4 mg/g液态碘的超高吸附性能。本项目的实施可为我国核应急提供有效的技术支撑。