Preparation Of Phosphorylated Mof-derived Carbon Materials And Their Adsorption Properties For U(Ⅵ)

Nuclear resources are important strategic resources,which are important basis for the development of nuclear industry.In recent years,as a clean and green energy,nuclear energy has been highly concerned.Compared with other traditional energy sources,it has many advantages of environmental protection and high economic performance.However,while nuclear energy brings us the feasibility to solve the energy crisis,the waste rock and tailings produced in the mining process will bring huge pollution to the environment.Therefore,the effective treatment of radioactive contamination is attracting more and more attention all over the world,which is of great significance to human health and ecological environment protection.Porous carbon-based materials are widely used in adsorption,catalysis and electrochemistry due to their high porosity,excellent chemical stability and cheap and readily available sources.In recent years,the preparation of porous carbon-based materials with high performance by using metal-organic frameworks（MOFs）as templates in an inert gas atmosphere at high temperature has become a hot topic in the research of MOFs.The materials obtained by carbonization not only inherit the structural characteristics of MOFs,but also increase their specific surface area,improve their adsorption performance and overcome the disadvantage of poor stability in water,which is particularly important for adsorption research.In addition,the adsorption performance of porous carbon can be further improved through the design of MOFs structure and the post-modification synthesis method of functional groups.Therefore,the development of porous carbon with different precursors is of great value for the application and development of phosphorylated MOFS-derived porous carbon materials.Based on the above discussion,three MOFs materials（MOF-808,ZIF-8 and ZIF-67）with different ligands and different metal central atoms were synthesized by hydrothermal method as templates.The porous carbon-based materials were carbonized at 600℃and phosphorylated to obtain Zr O₂/PC-PO₄.PC-8（Si O₂）-PO₄,Co_5.47N/PC-PO₄.The structure of the material,the physical and chemical properties of the material before and after the adsorption of uranium（Ⅵ）and the adsorption mechanism were tested by the characterization method.Through the experiment of static adsorption conditions,we have studied the The effect of three adsorbents on the adsorption performance of U（Ⅵ）.The adsorption results show that the optimum p H value of uranium adsorption for the three materials is 5.5,and the adsorption time reaches the adsorption equilibrium at 20 min,360min and 150 min,respectively.The adsorption conforms to the quasi-second-order kinetics model.The adsorption capacity increased with the increase of the initial concentration of U（Ⅵ）.The adsorption isotherm fitting showed that the adsorption was in line with Langmuir isotherm adsorption model.With the increase of temperature,the adsorption amount increases,and the adsorption process is spontaneous endothermic process.When p H=5.5 and T=298.15 K,the theoretical maximum adsorption capacity of U（Ⅵ）by the three adsorbent materials is 391.54 mg/g（Zr O₂/PC-PO₄）.682.80 mg/g（PC-8（Si O₂）-PO₄）and 630.03 mg/g(Co_5.47N/PC-PO₄).Phosphorylated MOF derived carbon-based materials have excellent physical and chemical properties,and can be used as an ideal adsorption material for the removal of U（Ⅵ）from radioactive wastewater.