| Uranium is the most important element in the nuclear industry.However,uranium-containing wastewater will be generated during uranium mining and smelting,production of nuclear fuel components,and disposal of spent fuel.The negative impacts cannot be ignored.Therefore,the safe and efficient treatment of uranium-containing wastewater is an important research direction of nuclear environmental safety and sustainable development of nuclear energy.In this thesis,two kinds of UiO-66 composite materials（UiO-66-AO and Pd@UiO-66-NH2@PET）were synthesized based on UiO-66-NH2,U（VI）in solution was respectively removal by adsorption and catalytic reduction.The physical properties and chemical structure of these two materials were characterized,and the U（VI）removal ability of the two materials under different conditions was investigated.The main research content and results summarized as follows:（1）UiO-66-AO is prepared by the reaction of aza-Mike addition and amidoxime.The physical and chemical properties of the material are tested by FITR,XPS,XRD and N2adsorption-desorption.The results show that UiO-66-AO was successfully prepared.Compared with UiO-66-NH2,the UiO-66-AO crystal form maintained well,but the specific surface area was reduced to 422 m2/g.The results of batch experiments on U（VI）adsorption showed that the optimal adsorption initial solution p H of UiO-66-NH2 and UiO-66-AO are 6 and 5,In addition,UiO-66-AO has better U（VI）adsorption capacity than UiO-66-NH2.The adsorption process conforms to Langmuir model and quasi-second-order kinetics model.At 55°C and p H5,UiO-66-AO saturated adsorption capacity can reach a maximum of 232 mg/g（The initial U（VI）concentration of the solution is 250 mg/L）,the adsorption capacity can reach 85%of saturated adsorption in 1 h,the adsorption tends to equilibrium at 240 min;The adsorption efficiency of UiO-66-AO to U（VI）was as high as 95.3%in the adsorption experiments of simulated nuclear industry wastewater,which is much higher than other metal ions.（2）UiO-66-NH2@PET was obtained by co-irradiation grafting technology,ring-opening reaction and in-situ growth of MOFs,and then metal Pd was loaded on UiO-66-NH2@PET to prepare Pd@UiO-66-NH2@PET composite;Through a series of characterizations to analyze the chemical structure,surface morphology,thermal stability and elemental form of the material,The results show that PET-g-PGMA,UiO-66-NH2@PET and Pd@UiO-66-NH2@PET were successfully prepared;In the reaction system of formic acid and Pd@UiO-66-NH2@PET as reducing agent and catalyst respectively,the catalytic reduction performance of Pd@UiO-66-NH2@PET for U（VI）at different concentrations was studied.The experimental results show that both the temperature increase and the extension of the reaction time are conducive to the progress of the catalytic reduction reaction.The research on its recycling performance showed that the catalytic performance of the composite fabric was gradually lost after three cycles of use.Experiments with low concentrations of uranium showed that an increase in the solid-liquid ratio was favorable for the reduction of U（VI）.In order to study the effect of different groups on the catalytic performance of palladium,UiO-66-NH2 and diethanolamine supported palladium were used for comparison experiments.The results show that the catalytic performance of Pd@UiO-66-NH2@PET is better than that of palladium-supported PET@PET-DEA.That means UiO-66-NH2 makes the loading of metal Pd nanoparticles on the surface of PET fabrics more stable,while improving the catalytic activity of Pd. |
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