| In recent years, with the continuous development of global economy, the demand for electricity in all walks of life is becoming higher and huger and the fossil energy cannot satisfy the growing demand for electricity, so countries around the world have to look at the nuclear power. The high-speed development of nuclear power eases the human demand for energy, however, at the same time it also brings more serious environmental problems. As the process of the uranium resources exploitation and utilization produces a lot of wastewater containing uranium, if discharged directly without treatment, it will bring serious damage to the ecological environment and human health, thus the separation and enrichment of uranium in uranium waste water has been an important topic in the field of nuclear power research.Surface modification of functionalized mesoporous materials in the application of uranium wastewater treatment in recent years has been drawing many researchers' attention, a large number of studies have shown that mesoporous silica surface modification group has significant effect on improving the adsorption performance of mesoporous silica for uranium. Based on the present study that most of modified groups imported by functionalized mesoporous silica materials often have onlyone single working site with uranium, this topic proposes to explore the functional groups containing multiple working sites in mesoporous silica materials, in order to further improve the adsorption performance of mesoporous materials. The main research work has the following several aspects:1.Mesoporous silica MCM-41 is prepared by sol-gel method, and the synthetic mesoporous silica materials are characterized and analyzed by Fourier infrared spectroscopy, N2 adsorption-stripping, X-ray powder diffraction, scanning electron microscope and other methods. The results show that the synthetic mesoporous silica particle size is about 200~300nm and has good particle dispersion and uniform aperture and order hole.Surface area is 1052cm2/g, mesoporous silica is modified with Tetraethylenepentamine by using after-grafting, new uranium adsorbent MCM-TEPA modified by multi-amino nitrogen ligands is obtained.2.Then the adsorption behavior of mesoporous silica MCM-TEPA modified by multi-amino nitrogen ligands to uranium in water solution is studied by static adsorption method, including the influences of the solution pH, adsorption time, adsorbent dose, solution of initial concentration on adsorption performance. The results show that the solution pH has a significant influence on adsorption performance, which adsorption rate is the highest when pH is 5.2, and 40 minutes can reach equilibrium adsorption, the adsorption rate is 99%, the maximum adsorption capacity is 454mg/g when adding adsorbent 4.5mg. Mg in the initial concentration of uranium in a solution of 120mg/g; Kinetics and thermodynamics studies for the process of MCM-TEPA adsorption of uranium find that the adsorption is in line with the secondary dynamic model.3.3-Aminopropyltrimethoxysilane is used to modify mesoporoussilica, single amino modified MCM-NH2 adsorbent was prepared.Comparing MCM-NH2 with MCM-TEPA in uranium adsorption experiments, the results show that the MCM-NH2 adsorption saturation time is about 60 minutes; maximum adsorption capacity is 156mg/g. We can see clearly that the adsorption effect of MCM-TEPA for uranium is much better than the MCM-NH2, which showing that multiple amino working sites in multi-amino nitrogen ligands modified MCM-TEPA take place multiple ligand with uranyl ion, and thus strengthen the complexing effect with uranyl ion, speed up adsorption rate for uranium, shorten the adsorption equilibrium time, improve the adsorption quantity, and enhance the adsorption performance. |
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