高选择性识别Sr的大环冠醚桥联型周期性介孔有机硅(PMOs)制备及吸附行为研究

Strontium-90 is one of the highly radioactive fission products (FPs) in spent fuels. Due to the easy environmental migration and chemical similarity with calcium, strontium-90 can be accumulated in human body, which will cause fatal disease such as leukemia. Research on the adsorption materials of strontium is of great importance for environmental analysis and remediation after nuclear leakage accidents. However, so far, the reported adsorption materials were prepared by loading the extractant molecules of strontium to inert substrate via physical methods like impregnation or inclusion, which suffered from the leak of the extractant molecules during cycle use. Besides, the specific surface area of the materials was relatively small. Adsorption capacity and kinetic rate towards strontium still had large room to improve. This study is dedicated to developing novel macrocyclic ether bridged periodic mesoporous organosilicas (PMOs) for the study on the selective adsorption behavior towards strontium. The influences of the distribution of the functional groups and the steric effect on the materials' adsorption ability will be investigated.The kinetic controlling factors and adsorption mechanism will be determined. The radiolysis stability of PMOs adsorption material under γ-ray irradiation will be evaluated for the first time. Moreover, an extraction chromatographic process will be proposed for the selective separation of trace strontium in solution, which is to be applied for the treatment of simulated seawater contaminated in Fukushima nuclear accident.This study is expected to develop a new method for the preparation of adsorption materials highly-selective to strontium, and provide scientific supports for the researches on the steric effect in ordered mesoporous materials and host-guest interaction between crown ether and metals.

锶-90是一种高放射性核裂片元素，环境迁移能力极强，且同钙化学性质相似，容易在人体积累并引发白血病等疾病。研究锶的吸附材料对于环境监测分析以及核泄露事故去污修复均具有重要意义。现有的锶吸附材料的制备是将萃取剂通过浸渍、包络等物理方法负载于惰性载体材料上，萃取剂分子容易发生流失；并且材料比表面积不高，吸附容量和动力学速率均有待改善。为此，本项目拟基于可选择性识别锶的大环冠醚作为桥联基团来构建新型周期性介孔有机硅（PMOs）材料，并系统研究其吸附行为。将探索功能基团分布、空间效应对吸附性能的影响规律，确定吸附过程的动力学控制因素，阐明吸附机理；首次评估PMOs吸附材料的耐γ-射线辐照稳定性；建立一个可选择性分离微量锶的萃取色谱流程，对模拟福岛核事故锶-90超标海水进行分离。本项目预期将为锶-90选择性分离材料的制备提供新方法，为研究有序介孔材料空间效应、冠醚-金属主-客体相互作用提供科学依据。

锶-90是一种典型的放射性裂片元素，化学性质同钙相似，且迁移能力极强，严重威胁着环境安全和人类健康。研究锶的吸附材料对于环境监测分析以及核泄露事故去污修复均具有重要意义。现有的锶吸附材料的制备是将萃取剂通过浸渍、包络等物理方法负载于惰性载体材料上，萃取剂分子容易发生流失；并且材料比表面积不高，吸附容量和动力学速率均有待改善。为此，本项目基于可选择性识别锶的大环冠醚作为桥联基团来构建新型周期性介孔有机硅（PMOs）材料，并系统研究其吸附行为。. 项目的主要研究结果可归纳为下述几个方面：1）设计合成以大环冠醚顺式二环己基-18-冠-6为桥联基团的有机硅烷单体，并制备出新型的冠醚桥联型周期性介孔有机硅材料；2）考察功能单体组成、模板剂、水解缩合条件等因素对介孔材料结构、形貌及有序度的影响，优化合成方法，制备出具有高官能化程度（或接枝率）、且结构规整的冠醚桥联型周期性介孔有机硅材料，并系统表征其组成、结构、形貌、官能团含量及位置分布、比表面、孔体积、热稳定性等；3）系统研究了材料对溶液中 Sr(II)的吸附行为，考察了平衡时间、HNO3 浓度、初始离子浓度等因素对 Sr(II)吸附能力的影响，基于动力学模型拟合实验数据研究材料的吸附动力学，拟合吸附等温线，确定吸附过程的控制因素和机理，并结合材料的结构差异，探讨功能基团位置分布和空间效应对吸附行为的影响；4）加入特定干扰离子，考察材料对于 Sr(II)的选择性识别能力，并基于冠醚与金属离子主-客体化学作用、 “孔穴匹配效应”理论进行分析解释；5）基于优化的吸附材料，建立选择性分离微量 Sr(II)的萃取色谱流程，并验证其对模拟福岛核事故后的锶超标海水中Sr(II)的分离性能；6）评价了材料的耐γ-射线辐照稳定性。. 本项目研究成果已有23篇论文发表在国际SCI收录期刊上，申请国家发明专利8项。本项目为推进后续放射性裂片元素Sr(II)分离材料的研究奠定了良好的基础。