Studies On The Enrichment And Detection Process Of Several Inorganic Ions In Low Concentration

Uranium hexafluoride is an important intermediate in the process of nuclear material production. And it is the unique uranium compounds can be used for extracting 235U through gas centrifugal separation. It would inevitably produce fumes containing a small amount of uranium hexafluoride and hydrogen fluoride during the process of uranium hexafluoride production, storage, transportation or centrifugal separation of 235U. It is a technical problem how to directly recycle the low concentration of uranium in the alkaline solution, and make the solution to achieve discharge standard after the recycling in China National Nuclear Corporation. In addition, the uranium usually accreted with iron, aluminum, zinc, fluoride and other inorganic ions. Also U-Al alloy are usually used as the uranium fuel rods in a nuclear reactor. Therefore, it is also a difficult problem how to fast and conveniently detect the trace components in the nuclear industry.This thesis focuses on enrichment and recycle problem of low concentration of uranium from the sodium carbonate absorption liquid of uranium hexafluoride. And on the basis of the separation and recovery of uranium, we have developed and set up the method for detection of several common inorganic ions by fluorescent technology. Specific contents are as follows:Chapter 1. The introduction part mainly described common properties of uranium compounds and methods how to enrich uranium and how to detect other related ions. Based on the theoretical researches, we put forward our own points to resolve the problems.Chapter 2. We designed two new cheap and green polymer resins PSMA/CHA and PSMA/OPDA based on the poly(styrene-co-maleic anhydride). The optimum conditions for enriching uranium were obtained by investigating the effect of pH, temperature, time and content of resins. Next, we applied the PSMA/CHA resin in recovering uranium under the weak-acid condition. In addition, we have studied the coordination condition between the 1-nitroso-2-naphthol and uranium as well as enrichment of uranium from the effluent of UF6. All the data proved that our researches are meaningful and valuable since the amount of uranium could reach the national standard.Chapter 3. On the basis of enrichment of uranium, we have developed two fluoride fluorescent probes (L1H, L2H) based on HBT. We discovered that HBT-based fluorophore (L’H) containing hydroxyl group was easily synthesized and was found to be facilitated in monitoring fluoride and shown ratiometric fluorescence changes. It was worth noting that an aldehyde group in conjugation with HBT-based fluorophore core at the adjacent position of hydroxyl group (L2H) would elevate the sensitivity towards fluoride tremendously. Spectroscopic studies indicated that L1H and L2H interacted with fluoride anion and involved a two-step reaction:hydrogen bond formation and deprotonation. The mechanism of L2H binding with fluoride was confirmed by 1H NMR titration experiments and DFT computational calculations.Chapter 4. A novel Schiff base L3 which was easily synthesized by the condensation reaction of 2-aminophenol and L2H and could be used for detection of aluminum in ethanol as well as in aqueous solution. Among the detected metal ions, only Al3+ ion can induce a significant enhancement in fluorescence intensity. In addition, the binding details of L3-Al3+ complex were investigated by means of 1H NMR titration, infrared spectra and DFT computational studies.Chapter 5. A Zn2+ fluorescent probe L4 was synthesized with high sensitivity and selectivity. On the basis of previous results that fluorescent Al3+ probe L3 suffer from slight interferent with Zn2+, the probe L4 could selective recognize Zn2+ though modification of the structure by using aminobenzene instead of aminophenol. The coordination mode was identified by spectral studies and DFT computational studies.Chapter 6. A novel fluorescent Fe3+ probe L5 based on 2-(2-hydroxyphenyl)benzothiazole has been synthesized and characterized. Both UV-vis and fluorescence spectroscopic studies demonstrated that L5 displayed highly sensitive and selective towards Fe3+ over other metal ions in acetonitrile. The coordination mode of L5-Fe3+ complex was confirmed by the 1H NMR titration and IR spectra.