Yu Rui-Li, Li Qian-Fan, Li Zhen-Le, Wang Xiao-Yu, Xia Liang-Zhi
Department of Chemical Engineering, Dalian University of Technology, Dalian 116024, China.
ACS Appl Mater Interfaces. 2023 Jul 26;15(29):35082-35091. doi: 10.1021/acsami.3c07032. Epub 2023 Jul 17.
This study aimed to develop effective adsorbents for capturing radioactive iodine in nuclear power waste gas. Two zinc metal-organic frameworks (Zn-MOFs) were synthesized and found to have favorable properties such as a large surface area, thermal stability, surface rich in π-electron-containing nitrogen, and redox potential. Adsorption experiments revealed maximum capacities of 1.25 and 1.96 g g for the MOFs at 75 °C, with the pseudo-second-order kinetic model fitting the data well. The Langmuir equation provided a better fit in cyclohexane, with maximum adsorption amounts of 249 and 358 mg g for Zn-MOF-1 and Zn-MOF-2, respectively. The MOFs were also stable during six cycles of adsorption and desorption. Furthermore, electron transfer occurred due to the synergistic adsorption of Zn, N, and O atoms, resulting in the conversion of some iodine to polyiodide. Zn-MOF-2 exhibited better chemisorption than Zn-MOF-1 due to a smaller highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap. Notably, it was discovered that N-containing radicals had stronger interactions with iodine compared to radicals without N. These findings provide valuable insights into MOF synthesis and environmental protection.
本研究旨在开发用于捕获核电废气中放射性碘的有效吸附剂。合成了两种锌金属有机框架材料（Zn-MOFs），发现它们具有诸如大表面积、热稳定性、富含含π电子氮的表面以及氧化还原电位等良好特性。吸附实验表明，在75°C下，这些MOFs的最大吸附容量分别为1.25 g/g和1.96 g/g，伪二级动力学模型能很好地拟合数据。在环己烷中，朗缪尔方程拟合效果更好，Zn-MOF-1和Zn-MOF-2的最大吸附量分别为249 mg/g和358 mg/g。这些MOFs在六个吸附和解吸循环中也很稳定。此外，由于Zn、N和O原子的协同吸附发生了电子转移，导致一些碘转化为多碘化物。由于最高占据分子轨道（HOMO）-最低未占据分子轨道（LUMO）间隙较小，Zn-MOF-2比Zn-MOF-1表现出更好的化学吸附性能。值得注意的是，发现含N自由基与碘的相互作用比不含N的自由基更强。这些发现为MOF合成和环境保护提供了有价值的见解。
