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Design Optimization And Selectivity Of Inorganic Ion Exchangers For Radioactive Waste Remediation
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Book Synopsis Design, Optimization, and Selectivity of Inorganic Ion-exchangers for Radioactive Waste Remediation by : Dmitry Gennadievich Medvedev
Download or read book Design, Optimization, and Selectivity of Inorganic Ion-exchangers for Radioactive Waste Remediation written by Dmitry Gennadievich Medvedev and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The processes of development of nuclear weapons resulted in accumulation of thousands of curies of high-level radioactive waste. Liquid waste produced in the US has been stored in carbon steel tanks in highly alkaline (1-3 M NaOH, 6 M sodium salts) media for fifty years and leakage has occurred. One of the approaches to the solution of the problem of radioactive waste is to adsorb the nuclides on highly selective ion-exchange material, solidify in a glass matrix and dispose in a geological formation. The use of the ion-exchange technology is limited by the time of the sorbent-solution contact required to reduce the activity of the streams to acceptable levels. Inorganic ion-exchangers are promising materials due to their high radiation stability, extreme selectivity, and compatibility with the glass matrix. The contact time can be reduced by improving selectivities, kinetics, and capacities of the materials towards the target ions. This can be accomplished in part through understanding of the origin of ion-exchange selectivity. Crystalline zeotypes with minerals sitinakite (ideal formula Na2Ti2O3SiO4·2H2O) and pharmacosiderite (HM3(TO)4(GeO4)[subscript]x(SiO4)3[subscript]x M = Cs, Na, K+, T=Nb5+, Ge4+, Ti4+) structures are excellent candidates for selectivity studies because of their ion-exchange properties tunable by alterations of synthetic procedures, and isomorphous framework substitution. The Nb-substitution in titanium sites reduces the framework charge, whereas Ge substitution decreases the unit cell size if in titanium sites and increases if it in silicon sites. The compounds were hydrothermally synthesized in Ti/Si, Ti/Nb/Si, Ti/Ge/Si forms and characterized by structural and ion-exchange studies. The 25% Nb substitution in titanosilicate sitinakite resulted in enhanced selectivity for cesium and additional bond formation of cesium within the channel. The selectivity for cesium in germanium substituted pharmacosiderite also was correlated with the coordination environment within the channel. In the advanced stages of this study semi-crystalline (sodium nonatitanate) and amorphous (monosodium titanate) materials also were considered because of their remarkable strontium selectivity. In situ X-ray diffraction techniques revealed that the sodium nonatitanate precedes the formation of the TS phase in hydrothermal synthesis. This knowledge allowed us to design and synthesize material for combined cesium and strontium removal.
Book Synopsis Use of Novel Highly Selective Ion Exchange Media for Minimizing the Waste Arising from Different NPP and Other Liquids by : Esko Tusa
Download or read book Use of Novel Highly Selective Ion Exchange Media for Minimizing the Waste Arising from Different NPP and Other Liquids written by Esko Tusa and published by . This book was released on 2003 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Highly selective inorganic ion exchangers give new possibilities to implement and operate new innovative treatment systems for radioactive liquids. Because of high selectivity these ion exchangers can be used even in liquids of high salt concentrations. Only selected target nuclides will be separated and inactive salts are left in the liquid, which can be released or recategorized. Thus, it is possible to reduce the volume of radioactive waste dramatically. On the other hand, only a small volume of highly selective material is required in applications, which makes it possible to design totally new types of compact treatment systems. The major benefit of selective ion exchange media comes from the very large volume reduction of radioactive waste in final disposal. It is also possible to save in investment costs, because small ion exchanger volumes can be used and handled in a very small facility. This paper describes different applications of these highly selective ion exchangers, both commercial fullscale applications and laboratory tests, to give the idea of their efficiency for different liquids.
Book Synopsis Development of Inorganic Ion Exchangers for Nuclear Waste Remediation by :
Download or read book Development of Inorganic Ion Exchangers for Nuclear Waste Remediation written by and published by . This book was released on 2000 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: (1) Na2Ti2O3SiO4 ·2H2O(CST). This compound is the most highly selective Cs+ exchanger known and is also selective for Sr2+. The structure of this compound was solved from powder data and found to have a framework structure enclosing unidimensional tunnels. For alkali metals the exchange sites were found to vary depending upon the size of the cation. Li+ and Na+ are small enough to fit into framework sites which accommodate half the required cations. The remainder lie within the tunnels. The larger Cs+ cannot fit into the framework sites and can occupy only half the tunnel sites. Thus, only 25% of the total exchanger sites are available to Cs+. However, the Cs+ -O bonds that form are exactly equal to the sum of the radii for Cs+ and O2-. All other cations have a poorer fit and tend to be displaced by Cs+. In the presence of Na+ dual exchange occurs simultaneously as Na+ fills the framework sites and a second site inside the tunnels. As the sodium ion concentration increases the uptake of Cs+ site decreases to 0.05 - 0.1 meq/g in tank waste simulants. (2) Trisilicates: M(I)2M(IV) Si3O9 ·H2O, (M(I) = Na+, K+, M(IV) = Ti, Sn Zr, Ce). We have prepared a family of trisilicates and solved the crystal structures of three of them. These compounds have framework structures enclosing alternating large and small cavities. The cavity sizes vary with the size of the M(IV) cation. For example, the Ti phase does not take up Cs+ but the Zr phase exhibits very high Kd values for Cs+ (105 ml/g in groundwaters) and is even 1500 ml/g in 6M NaOH. The mixed phase Na2Zr0.75Sn0.25(Si3O9)·H2O shows even higher Kd values. The interchangeability of the M(IV) ion changes the size of the cavities and governs the selectivity. This is an excellent example of crystal engineering where substitutions within the framework change selectivities. (3) Pharmacosiderites: We have prepared a family of compounds based on the pharmacosiderite mineral structure, solved their structures and determined the ion siting. The titanium silicate version, K3H(TiO)4(SiO4)3 · nH2O has a structure that is similar to that of the CST compound. It exhibits a high affinity for both Cs+ and Sr2+.7 The Kd values have been considerably improved by partial substitution of Ge for Ti, another example of controlling selectivity. The structure of the Sr2+ phase is under investigation. Sodium Nonatitanate: This compound, of composition Na4Ti9O20 · nH2O is layered and the interlayer spacing varies with the water content. It is selective for Sr2+ in highly alkaline systems and the strontium is easily eluted with mild acid solutions. It works well under column flow conditions and is stable to irradiation. The main interference is Ca2+. Summary of Additional Studies: (4) We have developed a simple technique to remove Sr2+ from tank wastes that contain high levels of complexants. The scheme is to add a cation that is preferentially complexed and so releases the Sr2+ to the solution that is readily removed with our strontium selective sodium nonatitanate or CST. This really works! (5) We have prepared sodium micas and alumina and zirconia pillared clays that exhibit extremely high Kd values (>105) for Cs+ in contaminated groundwater. They are superior to zeolites for Cs+ removal and may be used as a barrier to Cs+ movement in soils. The sodium mica traps the Cs+ permanently. (6) We have prepared a sodium niobium silicate that appears to have a pyrochlore structure. It is highly selective for Sr2+ in the presence of Ca2+, Mg2+ and Na+.
Download or read book דער אדעסער פאלעסטינא-קאמיטעט written by and published by . This book was released on 1908 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of Inorganic Ion Exchangers for Nuclear Waste Remediation. 1998 Annual Progress Report by :
Download or read book Development of Inorganic Ion Exchangers for Nuclear Waste Remediation. 1998 Annual Progress Report written by and published by . This book was released on 1998 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: To expand the authors efforts to provide families of inorganic ion exchangers useful on a global scale. In carrying out this objective, they will synthesize a variety of ion exchange materials, determine their structures and where necessary alter these structures to build in the desired properties. The underlying thermodynamic, kinetic and molecular basis of ion exchange behavior will be elucidated and their suitability for nuclear waste remediation will be assessed. As of September 1, 1996, they have synthesized a number of highly selective inorganic ion exchangers, determined their crystal structures and elucidated the mechanism of exchange for a number of these exchangers.
Book Synopsis Treatment of Radioactive Waste Using Composite Ion Exchanger by : Eman El-Kady
Download or read book Treatment of Radioactive Waste Using Composite Ion Exchanger written by Eman El-Kady and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The long-lived radionuclides in radioactive waste have been considered to be dangerous pollutants, and their migration with groundwater is strongly affected by adsorption on the geologic materials. The presence of radionuclides and toxic metals in wastes is a major environmental concern. Such wastes arise from technologies producing nuclear fuels, and from laboratories working with radioactive materials. Various treatment technologies have been developed for the removal of heavy metals from water. The commonly used technologies for removing metal ions from effluents include chemical precipitation, lime coagulation, ion exchange. Synthetic organic-inorganic composite cation-exchange materials have received a great deal of attention because of their stability and reproducible analytical and electroanalytical applications. Organic polymers of composite material provide the mechanical strength and increase the surface area for more available exchangeable sites of the inorganic part. Nano composites of organic-inorganic cation-exchange materials prepared by sol-gel method are advance class of materials that are expected to provide many possibilities.
Book Synopsis High-capacity, Selective Solid Sequestrants for Innovative Chemical Separation by :
Download or read book High-capacity, Selective Solid Sequestrants for Innovative Chemical Separation written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The approach of this task is to develop high-capacity, selective solid inorganic ion exchangers for the recovery of cesium and strontium from nuclear alkaline and acid wastes. To achieve this goal, Pacific Northwest Laboratories (PNL) is collaborating with industry and university participants to develop high capacity, selective, solid ion exchangers for the removal of specific contaminants from nuclear waste streams.
Book Synopsis Treatment of Radioactive Waste with Ion Exchange Membrane Electrodialyzer by : Masukuni Ito
Download or read book Treatment of Radioactive Waste with Ion Exchange Membrane Electrodialyzer written by Masukuni Ito and published by . This book was released on 1962 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 848 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Operation and Control of Ion-exchange Processes for Treatment of Radioactive Wastes by : International Atomic Energy Agency
Download or read book Operation and Control of Ion-exchange Processes for Treatment of Radioactive Wastes written by International Atomic Energy Agency and published by . This book was released on 1967 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Nuclear Waste Treatment Using Novel Inorganic Ion Exchange Materials by : Lina Al-Hindi Al-Attar
Download or read book Nuclear Waste Treatment Using Novel Inorganic Ion Exchange Materials written by Lina Al-Hindi Al-Attar and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Application of Ion Exchange Processes for the Treatment of Radioactive Waste and Management of Spent Ion Exchangers by :
Download or read book Application of Ion Exchange Processes for the Treatment of Radioactive Waste and Management of Spent Ion Exchangers written by and published by . This book was released on 2002 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ion exchange is one of the most common and effective treatment methods for liquid radioactive waste. This book reviews the current literature on the subject and reports on the existing state of the art of the application of ion exchange processes for liquid radioactive waste treatments and of the management of spent ion exchange media.
Book Synopsis Sol - Gel Inorganic Ion Exchangers for Conditioning of Medium Level Radioactive Waste by :
Download or read book Sol - Gel Inorganic Ion Exchangers for Conditioning of Medium Level Radioactive Waste written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Origin of Selectivity in Tunnel Type Inorganic Ion Exchangers by :
Download or read book Origin of Selectivity in Tunnel Type Inorganic Ion Exchangers written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The removal of highly radioactive species 137Cs and 90Sr from Weapon's Grade Tank Waste is a daunting task. The tanks normally are 5-7M in Na+, 1-3M in NaOH but only (almost equal to)10-5M in the targeted species. Nevertheless several sorbents and ion exchangers have been found that are sufficiently selective to be considered for remediation purposes. We are involved in a collaborative study, joint with personnel at the Westinghouse Research Center, Sandia National Laboratory and University of Notre Dame to uncover the origins of this selectivity in these compounds. The presentation will be concerned with the framework of titanium silicates with the sitinikite and pharmacosiderite structures. Both compounds have been synthesized as pure titanium silicates or as Nb and Ge substituted forms. Their structures in the sodium and proton forms as well as the Cs+ and Sr2+ ion forms will be described together with insight into the exchange mechanism as determined by in situ X-ray studies of Cs+ exchange utilizing synchrotron radiation.
Book Synopsis THE PURIFICATION OF RADIOACTIVE WASTE SOLUTIONS WITH NATURAL INORGANIC ION EXCHANGERS: 3RD COMMUNICATION; THE EXCHANGE ABSORPTION OF CERIUM, RUTHENIUM AND ZIRCONIUM COMPLEXES ON RADGENDORF CLAY. by :
Download or read book THE PURIFICATION OF RADIOACTIVE WASTE SOLUTIONS WITH NATURAL INORGANIC ION EXCHANGERS: 3RD COMMUNICATION; THE EXCHANGE ABSORPTION OF CERIUM, RUTHENIUM AND ZIRCONIUM COMPLEXES ON RADGENDORF CLAY. written by and published by . This book was released on 1962 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Strategic Design and Optimization of Inorganic Sorbents for Cesium, Strontium and Actinides by :
Download or read book Strategic Design and Optimization of Inorganic Sorbents for Cesium, Strontium and Actinides written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The basic science goal in this project identifies structure/affinity relationships for selected radionuclides and existing sorbents. The task will apply this knowledge to the design and synthesis of new sorbents that will exhibit increased cesium, strontium and actinide removal. The target problem focuses on the treatment of high-level nuclear wastes. The general approach can likewise be applied to non-radioactive separations. The project involves a collaboration among four organizations, with each focused on a different aspect of the problem. This document is the final report on the three years of activities conducted at the University of Notre Dame, where the research focus was on the use of molecular modeling to understand ion exchange selectivity in titanosilicates and polyoxoniobate materials.
