Study On The Preparation And Uranium Adsorption Properties Of Zirconium-Based Metal Organic Framework Materials

With the continuous development of human society and industry,the issue of energy supply and demand has become increasing serious.As a clean and mature energy source,nuclear energy is recognized as the best energy source for replacing fossil energy.Uranium is the most important fuel in nuclear fission reactors.However,China’s uranium reserve is not enough for demand,and the supplyment of uranium resource heaviliy depend on imports.The uranium resource in the ocean is abundant.Therefore,it is necessary to develop uranium extraction technology from seawater is conducive to the long-term stable development of China’s nuclear power industry.In this paper,the zirconium-based metal organic framework adsorbent materials,such as MOF-808,the hierarchical porous UiO-66（HP-UiO-66）,HP-UiO-66-NH₂ and HP-UiO-66/dopamine（HP-UiO-66-DA）,were studied.The structure and properties of the adsorbent materials were characterized by various characterization methods and uranium adsorption experiments were carried out to research the effects of different factors on the uranium adsorption performance of the adsorbent materials.The adsorption mechanisms of the adsorbents were analyzed.MOF-808 material was prepared by solvothermal method.The uranium adsorption experiments showed that the optimum pH of MOF-808 material is 8.0.The kinetic adsorption experimental data showed that MOF-808 material has fast uranium adsorption capacity and can reach adsorption equilibrium within 1 hour.The maximum saturated adsorption capacity can reach 499 mg/g and the adsorption efficiency of low concentration uranium reaches 76%in the simulated seawater environment.After 3 cycles of adsorption and desorption,the adsorption efficiency of MOF-808 is always above 70%.HP-UiO-66 material was prepared by defect-induced solvothermal method.The prepared HP-UiO-66 has a specific surface area of 780 m²/g.In the uranium adsorption experiment,HP-UiO-66 material reached adsorption equilibrium in 5 minutes;the maximum adsorption capacity could reach 1217 mg/g;the adsorption efficiency of low concentration uranium reached 87%in the simulated seawater experiment.According to the results of XPS tests,the adsorption mechanism of uranyl ions on HP-UiO-66 is that the metal-oxygen bond in the metal organic framework material combines with the hydrolysis product of uranyl ion to form a metal-oxygen-uranium bond.HP-UiO-66-NH₂ and HP-UiO-66-DA materials were prepared by solvothermal method.The saturated adsorption capacities of the two materials were 1397 mg/g and 429 mg/g,respectively,and both reached adsorption equilibrium within 1 hour.In the simulated seawater and ion competition experiments,HP-UiO-66-NH₂ has a uranyl adsorption rate of 99%.The adsorption mechanism of HP-UiO-66-NH₂ on uranyl ions was obtained by XPS tests.The metal-oxygen bond in the metal organic framework material was combined with the hydrolysis product of uranyl ion to form metal-oxygen-uranium bond and the amino group on the body forms a nitrogen-oxygen-uranium bond with the uranyl ion.