Morphology Control Of ZIFs Materials And Their Application In Adsorption Of Iodine

Environment pollution and the shortage of clean energy have attracted great attention with the rapid development of industry and energy demand.Nuclear energy,as an efficient and environmentally friendly clean energy,is currently one of the main sources of electricity.However,how to effectively manage and deal with nuclear waste has become the main problem in nuclear energy production while developing nuclear energy.At present,the most mainstream methods are solvent washing method and solid-phase adsorption method.However,these methods also have some disadvantages,such as high price,environmental pollution,and low adsorption efficiency.Therefore,it is very necessary to develop efficient and green iodine adsorbents.The regulation of zeolite imidazole ester framework materials（ZIFs）has unlimited possibilities.In this paper,imidazole compounds with different functional groups were used as modification ligands to participate in the synthesis of ZIF-67 materials through in-situ synthesis modification and post synthesis modification,to control the surface morphology of zif-67 and optimize its pore structure.Two new composite materials ZIF-67（A）and ZIF-67（PSM A）were obtained,and their iodine adsorption properties were investigated to prepare efficient iodine adsorption materials.In this paper,the ZIF-67（A）with mixed coordination of 2-methylimidazole and imidazole compounds was synthesized for the first time using 2-methylimidazole as the main ligand and imidazole compounds as the modifying ligand.The composite retains the calcite crystal structure of ZIF-67and has a high degree of crystallinity.The pore structure of the material is modified while regulating the crystal surface morphology of ZIF-67（A）,and the specific surface area and pore volume of the material are increased based on retaining the microporous characteristics.The specific surface area increased from 1164 m²/g to 1436 m²/g（an increase of 23%）,and the pore volume increased from 0.64 cm³/g to 0.91 cm³/g（an increase of 42%）,reflecting the optimization of the material structure by the modified ligand.The addition of some in-situ modified ligands slightly affects the thermal stability of the material,but the main skeleton structure of ZIF-67（A）material remains stable at 300℃,which provides a solid foundation for the practical application of iodine adsorption.The composite maintains the calcite crystal structure of ZIF-67 while maintaining high crystallinity.The addition of post modified ligands also optimized the pore structure of the material and significantly increased its specific surface area and pore volume.The specific surface area increased form1164 m²/g to 1436 m^2/g compared with of ZIF-67（an increase of 21%）,and the pore volume increased from 0.64 cm³/g to 0.87 cm³/g（an increase of 36%）.The composite can maintain the stability of its skeleton structure at a high temperature of 330°C,reflecting the excellent thermal stability of the material.The liquid-phase and gas-phase iodine adsorption experiments were carried out on the two materials respectively.The experimental results showed that the materials modified with ligands containing more amino functional groups performed very well in both liquid phase and gas phase iodine adsorption experiments,which is much higher than that of ZIF-67.Moreover,the composite has large specific surface area and pore volume,but the materials modified with imidazole ligands without amino functional groups also have high specific surface area and large pore volume,and the iodine adsorption performance of the materials has not been greatly improved,indicating that the increase of specific surface area and pore volume is not necessarily related to the improvement of iodine adsorption performance.The ligands with more electron-donating amino functional groups also provide more adsorption active sites for the materials,which provides inspiration for the purposeful introduction of ligands with functional groups into MOF materials to improve the iodine adsorption performance of the materials in the future.