Dissertation > Excellent graduate degree dissertation topics show

Porous SiO_2 gel on radioactive liquid waste actinide separation , curing characteristics

Author: SuWei
Tutor: ZuoTianJun
School: Chinese Academy of Engineering Physics
Course: Radiation protection and environmental protection
Keywords: Porous silica gel Cerium Uranium Adsorption property High silica glass-ceramic
CLC: TL941.11
Type: Master's thesis
Year: 2011
Downloads: 101
Quote: 0
Read: Download Dissertation

Abstract


Sol-Gel technology was applied to synthesize porous silica gel by phase separation and supercritical drying. The structure property of synthesized porous silica gel were characterized by means of TG-DTA, SEM, FT-IR, Press Mercury Analyzer, Gas Adsorption Analyzer and so on. Discontinous process was applied to study the adsoptive property of porous silica gel to cerium ions, while the adsorptive property to uranium was studied using discontinuous process and dynamic adsorption test. High silica glass-ceramic solidification forms wraping the simulating element cerium are synthesized by sintering porous silica gel at lower temperature, which was analyzed by TG-DTA, XRD, SEM, leaching test and so on. Research results are as follows:Porous silica gel could be successfully fabricated by phase separation and supercritical drying. That one fabricated by phase seperation is a kind of light porous material which has the structure of contimous pore and network with high porosity, high skelen density, low apparent density, the pore size distribution of main mesopore and micropore, the basic structure unit of Si-O-Si and surface of a large number of hydroxyl groups and organic groups. Porous silica gel synthesized by phase separation has good thermal stability as the basic structure features are not changed significantly after heat-treatment at high temperature, while porous silica gel prepared by supercritical drying has sponge-like network structure and poor thermal stability. In summary, porous silica gel synthesized by phase separation has better performance than that synthesized by supercritical drying, so that our works were focoused on the adsorption-separation properties and solidification-enbeding properties of porous silica gel fabricated by phase separation in the studing of the separation-solidification of simulative High Radioactive Level of Liquid Waste.Porous silica gel synthesized by phase separation has fine adsorptive capacity to cerium and uranium, while a longer equilibrium adsorptive time to cerium was obtained. The adsorptive properties of porous silica gel to cerium and uranium are affected by sorbents’ quantity for a given initial concentration of cerium and uranium. Adsorptive mechanism of cerium and uranium on porous silica gel was more physic adsorption than chemical adsorption, and the main adsorption mechanism are different in different stage of the adsorptive reaction. The adsorptive properties of porous silica gel to uranium are affected by the pH value in solution, which are better in neutral and weak acid solution, while poorer in strong acid solution at pH<5.0. The adsorptive property parameters of porous silica gel to uranium are different when the initial concentration of uranium in solution is changed. The equilibrium adsorptive capacity increase with increasing the initial concentration of uranium in solution, while the equilibrium adsorptive rate and ratios decrease. When the species and states of other ions in solution are different, the adsorptive capacity of porous silica gel are also changed. Trivalent ions have greater influence on the adsorptive capacity of porous silica gel, while divalent and monovalent ions no influence. It keeps to Langmuir equation orderliness and quasi-Second order kinetic equation that porous silica gel adsorbed uranium. Therefore, uranium in the surface of porous silica gel is monolayer adsorption, and adsorption reaction is not a simple surface reaction process but the combination of a variety of reactions, which not only occurs on the surface of porous silica gel but also occurs in the grains. Dynamic adsorptive property are greatly influenced by the flow rate of solution.The dynamic equilibrium adsorptive capacity increases with decreasing the flow rate, while the migration rate of uranium is gradually reduced.High silica glass-ceramic solidification forms immobilizing cerium could be successfully synthesized by sintering in lower temperature not melting at higher temperature. Appearance character, compaction and density of solidification forms relate with the sintering temperature. Solidification forms are conducive to being sintered and the optimum sintering temperature is about 1150℃～1250℃. Cerium in the form of CeO2 crystals uniformly distribute in the high silica glass matrix. The results of leaching test show that high silica glass synthesized by sintering porous silica gel at the lower temperature has a good immobilizing performance. The normalized leaching rate of elements is significantly less than that of the current borosilicate glass solidification forms which have been applied to industry now.

Related Dissertations

  1. Study on Activated Carbon Supported Cerium Catalytic Ozone Oxidation of Chloramphenicol,X703
  2. Effect of Cerium on Photosynthesis of Maize Seedlings under Magnesium Deficiency,S513
  3. Cerium salt catalyzed 1,3 - dicarbonyl compounds and propargyl -Pot Synthesis of Substituted Furans research,O626.11
  4. Preparation and Performance Evaluation of Chitosan-based Composite Films,TB383.2
  5. La, Ce doped iron oxide nanoparticles and surface adsorption phase transition behavior of,TB383.1
  6. Two-step steam reforming and syngas properties of cerium -based oxygen carriers,TQ116.2
  7. Hydrothermal and Ion-exchange Synthesis of High-purity Micro/nano-CeO2,O614.332
  8. Preparation and Characterization of Ru/CeO2 Catalysts for Ammonia Synthesis,O643.36
  9. Experimental Research of Catalytic Combustion of Gasified Biomass Over Alumina Supported Pd and Ni Catalysts,TK16
  10. PVD technology to prepare platinum - doped cerium film its structure,O484.1
  11. Studies on Syntheses and Adsorption Properties for Heavy Metal Ions of Coal-Based Chelated Humic Resin,X703
  12. Effect of Rare Earth Ce on Microstructure，corrosion Resistance and Antibacterial Property of 1Cr17 Stainless Steel,TG142.13
  13. Research on Cutting Properties of Diamond Saw Blades and Falling Dust Design of Cutter,TG717
  14. Catalytic Combustion of Formaldehyde Over Cu-doped Mn-Ce-O Solid Solution Catalysts,O643.36
  15. Catalystic Combustion of 1,2-dichloroethane on Transition Metal Oxides,O643.3
  16. Rare Earth and the Corrosion Environment Impact on Electronic Aluminum Foil Corrosion,TM535
  17. Prepararation of Chelated Electrodes and by which Absorb and Disabsorb Uranium from Seawater Controllably and Naturally,TL21
  18. Geochemistry Characteristics of Migmatite Rocks and the Relationship with Uranium Mineralization in the 505 Area, Panzhihua District, Southwestern China,P619.14
  19. Preparation of Amidoxime Functionalized Mesoporous Silica and Its Adsorption Property of Uranium,P744
  20. Study on the Application of Resin of Chitosan Cerium Complex Microshperes (RCCM) to Clarify Beer,TS262.5
  21. Preparation and Property Research of the Copper-based Three-way Catalyst Doped with Nickel,O643.36

CLC: > Industrial Technology > Nuclear technology > Radioactive waste management and comprehensive utilization > Radioactive waste and its processing > Liquid radioactive waste processing > Curing
© 2012 www.DissertationTopic.Net  Mobile