| Uranium hexafluoride was used to separate the isotope 235 U and 238 U. Therefore, it is recognized as the most important chemical intermediates in nuclear fuel production process. In the process of producing/storing uranium hexafluoride, and separating 235 U, a small amount of uranium hexafluoride and hydrogen fluoride tend to be produced. Traditionally, uranium hexafluoride was reducted to uranium dioxide for nuclear power plants or nuclear weapons. However, in the process of application and processing, releasing redundant uranium hexafluoride into the environment can cause the key ecological problems.This paper aims at enriching and recycling uranium which is from the sodium carbonate absorption liquid of uranium hexafluoride. Based on this purpose, we put forward the more economic, environment friendly and efficient processing methods, and made a thorough research. The main point is divided into the following three parts:Chapter1. The introduction part discribed the main physical and chemical properties of uranium, and widespread use in modern industry. It also discussed how to process, enrich, separate and precipitate uranium. The traditional traditional processes methods of uranium mainly included: selective precipitation, solvent extraction, ion exchange adsorption, adsorption method and so on. And we discussed the characteristics and defects of those processes methods.Chapter2. In this work, we studied on the treatment process for uranium hexafluoride adsorption solution with isomers of Nitroso-Naphthol to recover uranium efficiently and to simplify the traditional alkalic disposal process, which possess definite advantages such as high efficiency, reasonable price and manageability. We optimized the adsorption condition deeply though pH, temperature, time and amount of adsorbents. The adsorption percentage was up to the maximum in a broad pH range and the residual uranium would meet the national discharge standard at the optimal conditions. Meanwhile, we hammer at the studies of adsorption mechanisms and structural characteristics. Adsorption equilibrium was mathematically described by Langmuir and Freundlich adsorption models. The pseudo-first-order and pseudo-second-order kinetic models were also investigated. In addition, the crystal structures together with elemental analysis, infrared spectra and 1H NMR were carried out to give the solid evidence that 1-NN and 2-NN were coordinated with uranium in the most stable form of η2 mode via the N-O bond at the same side. The ultimate results explained that 1-NN(1-Nitroso-2-naphthol) and 2-NN(2-Nitroso-1-naphthol) could recover uranium in low concentrations with favorable achievement.Chapter3. In this work, we choosed cheap polyvinyl chloride(PVC) particles and imidazole and its derivatives as raw material, through grafting reaction synthesized polymer imidazole ionic liquids [PVC-im]Cl and [PVC-amim]Cl with high efficiency. At the same time, by using common characterization methods, such as elemental analysis, Fourier Transform infrared spectroscopy(FT-IR) and scanning electron microscopy, we preliminarily determined the structure of these polymer imidazole ionic liquids. In the treatment of low concentration of uranium solution, further study in the process of enrichment on temperature, pH of the solution, concentration, reaction time, the dosage of polymer ionic liquids, the interference ions(Ni2 +, Mn2 +, Zn2 + and Cd2 +, Ca2 +, Cr3 +) were made. According to the experimental results, [PVC-im]Cl and [PVC-amim]Cl can enrich uranyl in partial neutral environment, and the adsorption can achieve balance in 3h. Through the comparative study of imidazole and 5-amino-4-formamide imidazole on the properties of the enrichment of uranium, we provided the basis for the later functionalization of polymer ionic liquid. |
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