新型石墨炔对酸性溶液中铀的捕获机理研究

Uranium is now the most commonly used nuclear fuel in the nuclear industry, which is also the one of the most common radioactive waste that has potential risks for the human survival environment and health directly. To overcome the difficulty of the low adsorption capacity and selectivity bottlenecks of the traditional solid phase extractant and enhance uranium recovery rate from radioactive wastewater, an excellent and new solid phase extractant is needed which is of either scientific significance or practical application for protecting environment and recycling uranium resource. Graphdiyne (GDY) is an artificial synthetic carbon material which features acetylene linkages and uniformly distributed pores that has been widely applications in catalysis, Li storage, solar cells, and field emission devices. However, GDY has not been reported previously in the literature being a solid phase extractant for the treatment of radioactive wastewater. This project will focus on the synthesis of graphdiyne that its aggregation structure can be adjusted by controlling the template agent and catalyst and used it as a solid phase extractant for the removal of U(VI) from acidic radioactive wastewater. The influence of environmental factors on the capture capability and the adsorption efficiency of U(VI) are studied in detail by the batch adsorption method and column adsorption experiment. On the basis of models fitting analysis and the characterization of microstructure, the capture mechanism of U(VI) in graphdiyne is proposed. The aim of this project is to synthesize graphdiyne based solid phase extractant with high U(VI) adsorption and separation performance, to summarize the correlation mechanism of the aggregation structure of graphdiyne and the reaction conditions, to reveal the interaction mechanism between U(VI) and adsorbing sites of graphdiyne. These results will lay some theory foundation for its actual application in the treatment of uranium-bearing radioactive wastewater. In addition, it will also provide valuable technical support for the improvement of the technology level of related technological process in nuclear fuel cycle of our country.

铀是目前核工业中最常用的核燃料，也是最常见的污染放射性废物之一，它对人类的生存环境和健康具有潜在的危害。寻找优秀的铀固相萃取剂为解决传统吸附材料吸附容量低、选择性差等瓶颈问题，提高放射性废水中铀的回收率，不仅具有科学意义，而且对于保护环境和回收铀资源也将具有重要的应用价值。针对石墨炔在废水处理领域的研究成果较少的问题。本项目拟以聚集态结构可调控的石墨炔为研究对象，系统研究其在酸性溶液条件下对铀的吸附分离性能，分析环境因素对铀捕获能力和吸附效率的影响规律，采用模型分析和微观结构表征方法，确定石墨炔对铀的捕获机理。通过本项目的实施，制备出对铀具有高吸附性能的石墨炔固相萃取剂。总结石墨炔聚集态结构与制备反应条件之间的关联机制，揭示石墨炔吸附位点结构与铀的微观作用机制，为其在含铀放射性废水的处理领域的实际应用奠定一定的理论基础，也为提升我国在核燃料循环中相关工艺过程的技术水平提供有价值的技术支撑。

含铀放射性废水的有效处理是放射性废物处理领域的重要难题之一，铀作为主要的核燃料其在核燃料循环各个工艺过程中随处可见。碳质固相萃取剂因具有优异的化学稳定性、比表面积大和能够完全燃烧等优点吸引了众多学者的目光。开展含铀放射性废水处理新材料的研究对实现核安全与环境保护、铀资源的回收再利用具有重要的可持续发展的综合经济效益。本项目采用改进的界面法宏量制备石墨炔，并提出石墨炔的制备能在周围环境条件下进行，无需保护气氛且通过增加反应容器的数目增大石墨炔的产量。在此基础上，对石墨炔作氧化处理成功获得具有明显羧基官能团缺陷的新型石墨炔，并成功用于酸性水溶液中铀的有效截留。同时，为了寻找对铀具有良好作用的功能基并以放射化学学科发展为方向，进行了混合价铁基和植酸功能基固相萃取剂的设计、制备和铀捕获机理的研究。此外，基于高放废液处理与处置的要求，开展了模拟高放废液硼硅酸盐玻璃固化体配方的设计相关研究工作。在本项目执行期间，采用多种光谱学分析方法对所制备的产物的结构、形貌、组成、材料形成过程等进行了多角度的分析与联合探讨。通过批次静态吸附法、动态柱吸附法、膜分离截留实验等方法，分别获取了不同固相萃取剂材料对铀的静态最大吸附容量、动态饱和吸附容量、吸附选择性等吸附性能与宏观行为。通过数学模型分析吸附数据结合吸附铀后材料的微观结构变化，探讨了相关材料对铀的捕获机理。本项目对深入认识石墨炔的结构以及其在放射化学领域的应用提供了有价值的数据支撑，为保持和加强我国在石墨炔材料研究方面的国际领先地位具有重大的影响，为石墨炔基碳质材料、亚铁基材料、植酸功能基材料在核燃料循环各个工艺过程中达到铀的清洁解控与回收的目的积累了丰富的吸附数据和设计方案。本项目也为实现石墨炔基材料在多个领域的实际应用和设计、制备新型高效核素固相萃取剂提供相应的材料化学合成方法学，以满足我国复杂含铀放射性废水的高效处理材料的需求。