Zhang Guangtao, Chong Ran, Zhou Xiaoyuan, Yang Junpu, Bai Yaoyao, Zhang Zhi-Hui, Lin Jian
School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an 710049, P. R. China.
Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Changzhou 213164, P. R. China.
Inorg Chem. 2024 Nov 18;63(46):22288-22296. doi: 10.1021/acs.inorgchem.4c04012. Epub 2024 Nov 6.
Porous metal-organic frameworks (MOFs) have shown great potential as adsorbents for capturing radioiodine, a major fission product generated during the reprocessing of nuclear fuel. However, studies exploring the correlation between the structure of MOFs and iodine uptake capacity remain notably rare. In this study, we introduce a new strategy for enhancing the iodine adsorption efficiency of MOFs by strategically varying the position of functional groups on the organic linkers. Employing ligand-functionalized UiO-67 MOFs, our findings reveal that -amino substitution of UiO-67--NH, proximal to the node of the dicarboxylate linker, markedly accelerates adsorption kinetics of iodine vapor in comparison to -amino substitution of UiO-67--NH, where the amino groups are oriented away from the node. In contrast, UiO-67--NH exhibits a higher adsorption capacity of 2.19 g/g, compared to 1.91 g/g for UiO-67--NH, attributable to its higher porosity. Furthermore, a competitive I/HO vapor adsorption study demonstrated that UiO-67--NH exhibits faster adsorption kinetics and higher selectivity for iodine in the presence of water vapor compared to UiO-67--NH. Additionally, the crucial influence of positional isomerism on enhancing iodine adsorption has been corroborated through Raman spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. These analyses reveal that the nitrogen atom positioned at the site demonstrates a stronger affinity for iodine molecules compared to the nitrogen atom at the site, thereby improving adsorption kinetics.
多孔金属有机框架材料（MOFs）作为捕获放射性碘的吸附剂已显示出巨大潜力，放射性碘是核燃料后处理过程中产生的主要裂变产物。然而，探索MOFs结构与碘吸附能力之间相关性的研究仍然非常罕见。在本研究中，我们引入了一种新策略，通过有策略地改变有机连接体上官能团的位置来提高MOFs对碘的吸附效率。使用配体功能化的UiO - 67 MOFs，我们的研究结果表明，与UiO - 67 - -NH中氨基远离节点的情况相比，在二羧酸连接体节点附近的UiO - 67 - -NH进行 - 氨基取代显著加速了碘蒸气的吸附动力学。相比之下，UiO - 67 - -NH的吸附容量为2.19 g/g，高于UiO - 67 - -NH的1.91 g/g，这归因于其更高的孔隙率。此外，一项竞争性的I₂/H₂O蒸气吸附研究表明，与UiO - 67 - -NH相比，UiO - 67 - -NH在水蒸气存在下对碘表现出更快的吸附动力学和更高的选择性。此外，通过拉曼光谱、X射线光电子能谱和密度泛函理论计算证实了位置异构对增强碘吸附的关键影响。这些分析表明，位于 位点的氮原子对碘分子的亲和力比 位点的氮原子更强，从而改善了吸附动力学。
