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Relevant bibliographies by topics / Crystalline silicotitanates (CST)

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Academic literature on the topic 'Crystalline silicotitanates (CST)'

Author: Grafiati

Published: 26 September 2023

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Journal articles on the topic "Crystalline silicotitanates (CST)"

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Chitra, S., R. Sudha, S. Kalavathi, A. G. S. Mani, S. V. S. Rao, and P. K. Sinha. "Optimization of Nb-substitution and Cs+/Sr+2 ion exchange in crystalline silicotitanates (CST)." Journal of Radioanalytical and Nuclear Chemistry 295, no. 1 (May 12, 2012): 607–13. http://dx.doi.org/10.1007/s10967-012-1812-0.

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Nyman, M., T. M. Nenoff, Y. Su, M. L. Balmer, A. Navrotsky, and H. Xu. "New Crystalline Silicotitanate (CST) Waste Forms: Hydrothermal Synthesis and Characterization of CS-SI-TI-O Phases." MRS Proceedings 556 (1999). http://dx.doi.org/10.1557/proc-556-71.

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AbstractThe radioactivity of the Hanford site waste tanks is primarily from 137Cs and 90Sr, of which can both be selectively removed from solution using a crystalline silicotitanate (CST) ion exchanger. We are currently seeking waste forms alternative to borosilicate glass for Cs-CSTs. In order to obtain a fundamental basis for the development of an alternative waste form, we are investigating synthesis and characterization of CST component phases, namely Cs-Si-Ti-O phases. Two novel Cs-Ti-Si-O phases (one porous, one condensed) have been hydrothermally synthesized, characterized and evaluated as waste form candidates based on chemical and thermal stability, leachability, and ion exchange capabilities.

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Nyman, May, James L. Krumhansl, Carlos Jove-Colon, Pengchu Zhang, Tina M. Nenoff, Thomas J. Headley, Yali Su, and Liyu Li. "Chemical Interactions of UOP IONSIV IE-911 (CST) with SRS Waste Simulants." MRS Proceedings 713 (2002). http://dx.doi.org/10.1557/proc-713-jj12.4.

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ABSTRACTIE-911 is a bound form of cystalline silicotitanate (CST) that was extensively tested for removing 137Cs from the Savannah River Site (SRS) tank wastes. In some simulant tests, column plugging incidents were observed, which led to thorough investigations to determine the causes and to develop protocols to avoid future plugging incidents. A related problem was the apparent decrease in Cs scavenging capability in some long-term tests. Our studies revealed that the interaction of IE-911 with the highly basic, high ionic strength, SRS average salt simulant could result in precipitation of; 1) poorly crystalline Nb-oxide, or 2) aluminosilicate zeolitic phases. The source for the Nb-oxide precipitate was determined to be a minor impurity phase that is a byproduct of CST manufacturing. The mechanisms of dissolution and re-precipitation of this phase in column pretreatment solution were investigated, and a protocol to rid IE-911 of this impurity was devised. The source material for the aluminosilicate zeolite precipitate was determined to be predominantly from the waste solution rather than the IE-911. Solubility experiments coupled with a thermodynamic analysis provided a protocol to predict when aluminosilicate precipitation will and will not occur. Finally, it was also established that aluminosilicate precipitation on the surfaces of the IE-911 granules could also account for an apparent decrease in equilibrium Kd and decrease in kinetics of Cs sorption.

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Gu, B. X., L. M. Wang, S. X. Wang, and R. C. Ewing. "Radiation Effects on Materials in the Near-Field of a Nuclear Waste Repository." MRS Proceedings 663 (2000). http://dx.doi.org/10.1557/proc-663-883.

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ABSTRACTThe long-term radiation effects on materials in the near-field of a nuclear waste repository have been evaluated using accelerated laboratory experiments with energetic electron or ion beam irradiation. The materials studied include: zeolites, layered silicates (smectite clay and mica), as well as crystalline silicotitanate (CST) which is an important ion exchange material for the chemical separation of high-level liquid radioactive wastes.In situ transmission electron microscopy (TEM) during irradiation by energetic electrons and ions has shown that all of the studied materials are susceptible to irradiation-induced amorphization. At room temperature, complete amorphization was observed after ionizing doses of 1010 ∼ 1012 Gy or displacement doses on the order of 0.1 dpa (equivalent to doses received in 400-1,000 years for a high-loading nuclear waste form). Amorphization may be preceded or accompanied by dehydration, layer spacing reduction and gas bubble formation. In the case of zeolites, CST and some layered silicates, radiation effects are significantly enhanced at higher temperatures. Our experiments have shown that amorphization or even partial amorphization will cause a dramatic reduction in ion exchange and sorption/desorption capacities for radionuclides, such as Cs and Sr. Because the near-field or chemical processing materials (e.g. zeolites or CST) will receive a substantial radiation dose after they have incorporated radionuclides, our results suggest that radiation effects may, in some cases, retard the release of sorbed or ion-exchanged radionuclides.

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Campbell, Emily L., Amy M. Westesen, and Reid A. Peterson. "Investigation into Na and Cs activity coefficients in high salt solutions to support Cs removal in Hanford tank waste." Radiochimica Acta, September 8, 2023. http://dx.doi.org/10.1515/ract-2023-0134.

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Abstract The treatment of Hanford tank waste is one of the most technically challenging environmental cleanup activities for the U.S. Department of Energy to date. To expedite the processing of liquid waste stored in underground tanks in southeastern Washington state, it is necessary to remove the significant dose contributor, 137Cs. Toward this effort, ion exchange with crystalline silicotitanate (CST) has been employed as part of the Tank Side Cesium Removal system. The model used to predict Cs exchange onto CST was developed using activity coefficients calculated from the Bromley equation. A series of batch contact tests that varied in [Na] were conducted to look at the impact of Na concentration on Cs distribution. Experimental distribution ratios (K d) were compared to the distribution ratios predicted using three different activity coefficient models: (1) commercially available HSC software, (2) the Bromley equation, and (3) a simplified approach adapted from Marcos-Arroyo et al. Ultimately, the Bromley method underpredicted the effect of ionic strength on the Na activity coefficient (γ Na+), HSC overestimated the impact of ionic strength on the expected performance due to the Cs activity coefficient (γ Cs+), but the simplified approach predicted the experimental K d values quite well in a binary matrix. Expansion of this approach in complex matrices is necessary for application to Hanford tank waste.

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Dissertations / Theses on the topic "Crystalline silicotitanates (CST)"

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Milcent, Théo. "Mise en place d'une nouvelle méthodologie d'évaluation d'un échangeur d'ions minéral du point de vue de sa sélectivité : Cas particulier de l'optimisation structurale et microstructurale d'un silicotitanate cristallin (CST), appliqué à la décontamination d'effluents simultanément contaminés en Sr2+ et Cs+." Electronic Thesis or Diss., Montpellier, Ecole nationale supérieure de chimie, 2022. http://www.theses.fr/2022ENCM0010.

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Les alumino, titano et zircono-silicates zéolithiques sont des matériaux présentant des propriétés intéressantes pour de nombreuses applications dans la pétrochimie, l'agriculture, le médical, le stockage d'énergie ainsi que la décontamination d'effluents. Dans le domaine du traitement des effluents radioactifs, leurs propriété d'échange d'ions font de ces matériaux des extractants de radionucléides efficaces avec de bonnes sélectivités (e.g. césium ou strontium). Leurs compositions (le ratio Al/Si, Ti/Si, Zr/Si… ; la nature et la charge des métaux ; la nature, la charge, la concentration et la taille de l'ion échangeable) ainsi que la structure cristalline (amorphe, 2D lamellaire, 3D cage ou tunnel) vont avoir des effets sur les mécanismes d'échange ionique (cinétique, spécificité, stabilité). Ces paramètres vont aussi influencer la capacité de sorption ainsi que la sélectivité que le matériau a pour un ion. Lors de cette thèse, les relations structure/propriété de différents silicates seront étudiées dans le but d'appréhender les mécanismes de sorption. A cette fin, les synthèses de plusieurs silicates seront menées et optimisées. Par la suite, différentes techniques de caractérisation seront misent en place afin d'analyser les propriétés structurales, morphologiques et la composition des silicates. Enfin, ces matériaux seront mis en œuvre pour le traitement d'effluents modèles et d'effluents réels simulés, afin d'évaluer leurs performances et les mettre en lien avec leurs caractéristiques structurales et texturales
Alumino, titano and zircono-silicates zeolitic materials exhibit good performances in applications such as catalysis, gas separation and confinement. In addition, these kind of materials has been successfully used in different fields like petrochemistry, agriculture, medical, energy storage and nuclear decontamination. Their ion exchange properties make them very selective for radionuclides extraction (e.g. cesium or strontium) from wastewater treatment. Their composition (Al/Si, Ti/Si, Zr/Si ratio; “metal” nature and charge; labile ion nature, charge, size and concentration) and their framework structure (amorphous, 3D cage or tunnel) affect the ion exchange mechanism (i.e. kinetics, specificity, stability). These parameters may also modify the sorption capacity and the ion selectivity. In the present PhD, the relationship between structure and properties of several silicates will be studied in order to better understand their sorption mechanisms. To this end, the synthesis of different silicates will be performed and optimized. Then, their structures, morphologies and compositions will be analyzed by the application of different characterization techniques. Finally, this materials will be implemented to effluent treatments (i.e. model effluent and simulate real effluent) to evaluate their performances and find the connection between the structural and textural properties

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Kim, Sung Hyun. "Ion exchange kinetics of cesium for various reaction designs using crystalline silicotitanate, UOP IONSIV IE-911." Texas A&M University, 2003. http://hdl.handle.net/1969.1/282.

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Through collaborative efforts at Texas A&M University and Sandia National Laboratories, a crystalline silicotitanate (CST), which shows extremely high selectivity for radioactive cesium removal in highly concentrated sodium solutions, was synthesized. The effect of hydrogen peroxide on a CST under cesium ion exchange conditions has been investigated. The experimental results with hydrogen peroxide showed that the distribution coefficient of cesium decreased and the tetragonal phase, the major component of CST, slowly dissolved at hydrogen peroxide concentrations greater than 1 M. A simple and novel experimental apparatus for a single-layer ion exchange column was developed to generate experimental data for estimation of the intraparticle effective diffusivity. A mathematical model is presented for estimation of effective diffusivities for a single-layer column of CST granules. The intraparticle effective diffusivity for Cs was estimated as a parameter in the analytical solution. By using the least square method, the effective diffusivities of 1.56 ± 0.14 x 10-11 m2/s and 0.68 ± 0.09x 10-11 m2/s, respectively, were obtained. The difference in the two values was due to the different viscosities of the solutions. A good fit of the experimental data was obtained which supports the use of the homogeneous model for this system. A counter-current ion exchange (CCIX) process was designed to treat nuclear waste at the Savannah River Site. A numerical method based on the orthogonal collocation method was used to simulate the concentration profile of cesium in the CCIX loaded with CST granules. To maximize cesium loading onto the CST and minimize the volume of CST, two design cases of a moving bed, where the fresh CST is pulsed into the column at certain periods or at certain concentration of cesium, were investigated. Simulation results showed that cesium removal behavior in the pilot-scale test of CCIX experiment, where the column length is 22 ft and the CST is pulsed 1 ft in every 24 hours, was well predicted by using the values of the effective diffusivities of 1.0 to 6.0 × 10-11 m2/s.

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Book chapters on the topic "Crystalline silicotitanates (CST)"

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Miller, James E., Norman E. Brown, James L. Krumhansl, Daniel E. Trudell, Rayford G. Anthony, and C. V. Philip. "Development and Properties of Cesium Selective Crystalline Silicotitanate (CST) Ion Exchangers for Radioactive Waste Applications." In Science and Technology for Disposal of Radioactive Tank Wastes, 269–86. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4899-1543-6_21.

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Conference papers on the topic "Crystalline silicotitanates (CST)"

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Mimura, Hitoshi, Minoru Matsukura, Tomoya Kitagawa, Fumio Kurosaki, Akira Kirishima, Daisuke Akiyama, and Nobuaki Sato. "Evaluation of Adsorption Properties of U(VI) for Various Inorganic Adsorbents." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81338.

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Large amounts of highly contaminated water over 800,000 m3 accumulated in the reactor, turbine building and the trench in the facility were generated from the nuclear accident of Fukushima NPS (BWR) caused by the Great East Japan Earthquake. At present, the cold shutdown is completed stably by the circulating injection cooling system (SARRY, KURION) for the decontamination of radioactive nuclides such as 134Cs and 137Cs using zeolites and crystalline silicotitanate (CST). Further, the Advanced Liquid Processing System (ALPS) is under operation for the decontamination of 62 nuclides such as 90Sr, 129I and 60Co, etc. However, the adsorption behaviors of actinoids through the decontamination systems are complicated, and especially their adsorption properties for zeolites and CST, major inorganic adsorbents, are not yet clarified. In near future, the decontamination of actinoids leached from the crushed fuel debris will be an important subject. In this study, the practical adsorption properties of U(VI) for various inorganic adsorbents were evaluated under different solution conditions. The adsorption properties (distribution behaviors and adsorption kinetics) were evaluated by batch adsorption method; 19 kinds of inorganic adsorbents including zeolites and CST (crystalline silicotitanate) were contacted with U(VI)) solutions. The conditions of 5 kinds of U(VI) solutions were as follows; Solution 1: [U(VI)] = 50 ppm, initial pH = 0.5 ∼ 5.5 Solution 2: [U(VI)] = 50 ppm, [NaCl] = 0.1 M, initial pH = 4.0 Solution 3: [U(VI)] = 50 ppm, [CaCl2] = 0.1 M, initial pH = 4.0 Solution 4: [U(VI)] = 4.84 mM, [NaCl] = 0.1 M, initial pH = 3.18 Solution 5: [U(VI)] = 4.86 mM, 2,994 ppm boric acid/30% seawater, initial pH = 4.25 The uptake (%) and distribution coefficient (Kd. cm3/g) were estimated by counting the radioactivity using NaI(Tl) scintillation counter and liquid scintillation counter. In the simple Solution 1, the Kd values for zeolites increased linearly with equilibrium pH up to pH 7. The Kd value for tin hydroxide had a maximum profile around pH 7 and a relatively large Kd value above 104 cm3/g was obtained. In the presence of NaCl and CaCl2 (Solution 2 and 3), relatively large Kd values above 102 cm3/g were obtained, other than mordenite and clinoptilolite, and the effect of [Ca2+] on U(VI) uptake was larger than that of [Na+]. In Solution 4 containing high concentration of U(VI), the uptake(%) was considerably lowered, while that for zeolite A, X and Y was estimated over 20%. Similar tendency was observed in Solution 5, and, in the case of granulated potassium titanate, yellow precipitate was observed on the surface due to the increase of equilibrium pH up to 5.25. The adsorption behavior of U(VI) on inorganic adsorbents is mainly governed by three steps; ion exchange, surface precipitation of hydrolysis species and sedimentation depending on equilibrium pH, and hence it should be noted the change of U(VI) chemical species. These basic adsorption data are useful for the selection of inorganic adsorbents in the Fukushima NPS decontamination process.

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Denton, Mark S., and Mercouri G. Kanatzidis. "Innovative Highly Selective Removal of Cesium and Strontium Utilizing a Newly Developed Class of Inorganic Ion Specific Media." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16221.

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Highly selective removal of Cesium and Strontium is critical for waste treatment and environmental remediation. Cesium-137 is a beta-gamma emitter and Strontium-90 is a beta emitter with respective half-lives of 30 and 29 years. Both elements are present at many nuclear sites. Cesium and Strontium can be found in wastewaters at Washington State’s Hanford Site, as well as in wastestreams of many Magnox reactor sites. Cesium and Strontium are found in the Reactor Coolant System of light water reactors at nuclear power plants. Both elements are also found in spent nuclear fuel and in high-level waste (HLW) at DOE sites. Cesium and Strontium are further major contributors to the activity and the heat load. Therefore, technologies to extract Cesium and Strontium are critical for environmental remediation waste treatment and dose minimization. Radionuclides such as Cesium-137 and Strontium-90 are key drivers of liquid waste classification at light water reactors and within the DOE tank farm complexes. The treatment, storage, and disposal of these wastes represents a major cost for nuclear power plant operators, and comprises one of the most challenging technology-driven projects for the DOE Environmental Management (EM) program. Extraction technologies to remove Cesium and Strontium have been an active field of research. Four notable extraction technologies have been developed so far for HLW: solvent extraction, prussian blue, crystalline silicotitanate (CST) and organic ion-exchangers (e.g., resorcinol formaldehyde and SuperLig). The use of one technology over another depends on the specific application. For example, the waste treatment plant (WTP) at Hanford is planning on using a highly-selective organic ion-exchange resin to remove Cesium and Strontium. Such organic ion-exchangers use molecular recognition to selectively bind to Cesium and Strontium. However, these organic ion-exchangers are synthesized using multi-step organic synthesis. The associated cost to synthesize organic ion-exchangers is prohibitive and seriously limits the scope of applications for organic ion-exchangers. Further issues include resin swelling, potential hydrogen generation and precluding final disposal by vitrification without further issues. An alternative to these issues of organic ion-exchangers is emerging. Inorganic ion-exchangers offer a superior chemical, thermal and radiation stability which is simply not achievable with organic compounds. They can be used to remove both Cesium as well as Strontium with a high level of selectivity under a broad pH range. Inorganic ion-exchangers can operate at acidic pH where protons inhibit ion exchange in alternative technologies such as CST. They can also be used at high pH which is typically found in conditions present in many nuclear waste types. For example, inorganic ion-exchangers have shown significant Strontium uptake from pH 1.9 to 14. In contrast to organic ion-exchangers, inorganic ion-exchangers are not synthesized via complex multi-step organic synthesis. Therefore, inorganic ion-exchangers are substantially more cost-effective when compared to organic ion-exchangers as well as CST. Selective removal of specified isotopes through ion exchange is a common and proven treatment method for liquid waste, yet various aspects of existing technologies leave room for improvement with respect to both cost and effectiveness. We demonstrate a novel class of inorganic ion-exchangers for the selective removal of cesium and strontium (with future work planned for uranium removal), the first of a growing family of patent-pending, potentially elutable, and paramagnetic ion-exchange materials [1]. These highly selective inorganic ion-exchangers display strong chemical, thermal and radiation stability, and can be readily synthesized from low-cost materials, making them a promising alternative to organic ion-exchange resins and crystalline silicotitanate (CST). By nature, these inorganic media lend themselves more readily to volume reduction (VR) by vitrification without the issues faced with organic resins. In fact, with a simple melting of the KMS-1 media at 650–670 deg. C (i.e., well below the volatilization temperature of Cs, Sr, Mn, Fe, Sb, etc.), a VR of 4:1 was achieved. With true pyrolysis at higher temperatures or by vitrification, this VR would be much higher. The introduction of this new family of highly specific ion-exchange agents has potential to both reduce the cost of waste processing, and enable improved waste-classification management in both nuclear power plants (for the separation of Class A from B/C wastes) and DOE tank farms [for the separation of low level waste (LLW) from high level waste (HLW)]. In conclusion, we demonstrate for the first time a novel inorganic ion-exchanger for the selective removal of Cesium and Strontium. These inorganic ion-exchangers are chemical, thermal and radiation stable. These inorganic ion-exchangers can be synthesized in a cost-effective way which makes them significantly more effective than organic ion-exchange resin and CST. Finally, new thermal options are afforded for their final volume reduction, storage and disposal.

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Reports on the topic "Crystalline silicotitanates (CST)"

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Andrews, M. K., and J. R. Harbour. Glass formulation requirements for Hanford coupled operations using crystalline silicotitanates (CST). Office of Scientific and Technical Information (OSTI), May 1997. http://dx.doi.org/10.2172/554132.

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DARREL, WALKER. Digestion of Crystalline Silicotitanate (CST). Office of Scientific and Technical Information (OSTI), November 2004. http://dx.doi.org/10.2172/837905.

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Jacobs, R. A. Powdered Crystalline Silicotitanate (CST) Isotherms for SRS Wastes. Office of Scientific and Technical Information (OSTI), February 1999. http://dx.doi.org/10.2172/4821.

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Gauglitz, Phillip A., Courtney LH Bottenus, Gregory K. Boeringa, Carolyn AM Burns, and Philip P. Schonewill. Drying of Crystalline Silicotitanate (CST) Beds by Air Flow. Office of Scientific and Technical Information (OSTI), July 2019. http://dx.doi.org/10.2172/1545578.

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Andrews, M., T. Fellinger, D. Ferrara, J. Harbour, and D. Herman. Vitrification of cesium-loaded crystalline silicotitanate (CST) in the shielded cells melter. Office of Scientific and Technical Information (OSTI), September 1997. http://dx.doi.org/10.2172/352918.

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Miller, J. E., and N. E. Brown. Development and properties of crystalline silicotitanate (CST) ion exchangers for radioactive waste applications. Office of Scientific and Technical Information (OSTI), April 1997. http://dx.doi.org/10.2172/469131.

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WILLIAM, WILMARTH. Reactivity of Crystalline Silicotitanate (CST) and Hazardous Metal/Actinide Loading During Low Curie Salt Use. Office of Scientific and Technical Information (OSTI), November 2004. http://dx.doi.org/10.2172/837909.

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HANG, THONG, and DANIEL MCCABE. CRYSTALLINE SILICOTITANATE (CST) ION EXCHANGE MEDIA PERFORMANCE EVALUATIONS TO SUPPORT TSCR DSA IX MEDIA EQUILIBRIUM CONTACTS. Office of Scientific and Technical Information (OSTI), September 2021. http://dx.doi.org/10.2172/1822676.

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Andrews, M. K., and P. J. Workman. Glass formulation development and testing for the vitrification of DWPF HLW sludge coupled with crystalline silicotitanate (CST). Office of Scientific and Technical Information (OSTI), September 1997. http://dx.doi.org/10.2172/564994.

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Taylor-Pashow, K. M. L., T. B. Edwards, and C. A. Nash. Pretreatment of Crystalline Silicotitanate (CST) and development of a digestion standard to support Tank Closure Cesium Removal (TCCR). Office of Scientific and Technical Information (OSTI), March 2019. http://dx.doi.org/10.2172/1501827.

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