高性能功能化凝胶材料的合成及其对裂变产物锝的分离行为研究

Technetium is one of the fission products of spent fuel which has a high-yield and long half-life. Technetium has strong entironment migration tendency during geological disposal of high-level waste solidification. Based on the need of the long-lived fission product separation-transmutation from HLLW , we aim to prepare a high performance quaternary ammonium type adsorption material which has excellent acid resistance, radiation resistance, good selectivity and high adsorption capacity for the separation of technetium in nuclear fuel reprocessing, The adsorption behavior and mechanism will be investigated. The adsorption and separation performance will be studied in simulated radioactive waste water. The high performance quaternary ammonium type organic/inorganic hybrid gel materials based on dimethylaminoethyl methacrylate quaternized with different 1-bromoalkanes were synthesized in the nano-inorganic dispersion by radiation-induced polymerization and crosslinking. FTIR, XPS, NMR and other methods will be used to study the synthetic process and mechanism. The mechanical properties and the physical /chemical stability in strong acid and strong radiation condition will be studied. Secondly, the adsorption capacity, partition coefficient, the adsorption mechanism will be investigated by studying on the adsorption and separation of technetium and rhenium under different system parameters. Finally, the adsorption and separation behavior of technetium will be further verified by comparing with the adsorption parameters of simulated radioactive waste. This work will pave the way to provide a new method for the separation of Tc from radioactive waste.

锝是乏燃料中产额高、寿命长的裂变产物之一，在高放废液固化体地质处置中具有环境迁移性强等特点。基于放射性废液中长寿命裂变产物的分离-嬗变科学需求，本项目拟根据后处理流程特点和锝在不同溶液体系的化学形态，制备高强度、耐酸、耐辐照、选择性好、吸附容量大的高性能季铵型凝胶吸附材料，研究其对锝的吸附行为和机理，并通过模拟放射性废液进行验证实验，考察其分离吸附性能。申请者将通过辐射技术和有机无机杂化手段，在无机纳米分散体系中辐射聚合与交联甲基丙烯酰氧乙基二甲基烷基溴化铵等单体，制备新型高性能季铵型凝胶材料，利用FTIR、XPS、NMR等方法对合成的材料进行表征，研究提高其性能的策略；然后，研究该材料在不同体系中对锝及铼的吸附与分离，测定吸附容量、分配系数等参数，提出该材料对锝的吸附机理；最后，通过放射性废液进行验证实验，获取净化系数及操作条件等关键参数，提出从乏燃料后处理流程中分离提取锝的新方法

锝是乏燃料中产额高、寿命长的裂变产物之一，在高放废液固化体地质处置中具有环境迁移性强等特点。基于放射性废液中长寿命裂变产物的分离—嬗变科学需求，本项目拟根据后处理流程特点和锝在不同溶液体系的化学形态，制备高强度、耐酸、耐辐照、选择性好、吸附容量大的高性能季铵型硅胶吸附材料，研究其对锝的吸附行为和机理，并通过模拟放射性废液进行验证实验，考察其分离吸附性能。本文基于硅胶具有良好的化学和耐辐照稳定性、热稳定性和强的机械性等特点，以多孔硅胶为基体，采用γ-辐射接枝技术进行表面功能化修饰，考察了硅胶表面结构、烷基化单体、γ-辐射辐照剂量及功能单体等条件对硅基表面接枝率的影响规律，利用 FTIR、XPS、NMR 等方法对合成的材料进行表征，研究提高其性能的策略；然后，研究该材料在不同体系中对锝及铼的吸附与分离，测定吸附容量、分配系数等参数，提出该材料对锝的吸附机理；最后，依据我国规划的商用乏燃料燃耗和后处理流程特点，开展模拟放射性废液中高性能季铵型凝胶分离材料分离提取锝的验证研究，提出从乏燃料后处理流程中锝分离提取的新方法。研究结果表明，采用三甲基氯硅烷进行硅胶烷基化，然后在40kGy的γ-辐射剂量下，以4.0 mol·L-1的4-乙烯基吡啶为功能单体进行辐射接枝，接枝率可达到21%，理论饱和吸附容量可达到71.08mg·g-1。在溶液硝酸为0. 5mol/L、[Tc(Ⅶ)]为10mg/L的条件下，硅基吡啶功能化材料对Tc(Ⅶ)的分配系数可达370，静态吸附平衡时间为35min。