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Sample records for mordenite

  1. Disilane-modified mordenite zeolites

    SciTech Connect

    Yan, Y.; Vansant, E.F. )

    1990-03-22

    The effective pore size of H-mordenite zeolite can be decreased by implantation of disilyl compounds. Chemisorption of disilane at high temperature results in denser packing of the implanted entities on the external surface. This in turn enhances the pore narrowing effect. After hydrolysis-dehydration, the external surface of the disilanated zeolite can be reactivated by partial rehydration; thus a successive modification of the zeolite surface is possible.

  2. Chemical Resistivity of Silver Mordenite and Berl Sadles

    SciTech Connect

    Holcomb, H.P.

    2001-05-17

    This report discusses results of testing to determine the chemical resistance of pellets of silver mordenite and silver mordenite, reduced form. For comparison Berl saddles were tested under similar conditions. Silver mordenite has been proposed as a replacement for the saddles that remove iodine in the off-gas treatment system from the canyon dissolvers.

  3. Recycle of iodine-loaded silver mordenite by hydrogen reduction

    SciTech Connect

    Burger, L.L.; Scheele, R.D.

    1982-11-01

    In 1977 and 1978, workers at Idaho National Engineering Laboratory (INEL) developed and tested a process for the regeneration and reuse of silver mordenite, AgZ, used to trap iodine from the dissolver off-gas stream of a nuclear fuel reprocessing plant. We were requested by the Airborne Waste Management Program Office of the Department of Energy to perform a confirmatory recycle study using repeated loadings at about 150/sup 0/C with elemental iodine, each followed by a drying step at 300/sup 0/C, then by iodine removal using elemental hydrogen at 500/sup 0/C. The results of our study show that AgZ can be recycled. There was considerable difficulty in stripping the iodine at 500/sup 0/C.; however, this step went reasonably well at 550/sup 0/C or slightly higher, with no apparent loss in the iodine-loading capacity of the AgZ. Large releases of elemental iodine occurred during the drying stage and the early part of the stripping stage. Lead zeolite, which was employed in the original design to trap the HI produced, is ineffective in removal of I/sub 2/. The process needs modification to handle the iodine. Severe corrosion of the stainless steel components of the system resulted from the HI-I/sub 2/-H/sub 2/O mixture. Monel or other halogen-resistant materials need to be examined for this application. Because of difficulty with the stripping stage and with corrosion, the experiments were terminated after 12 cycles. Thus, the maximum lifetime (cycles) of recycle AgZ has not been determined. Mechanistic studies of iodine retention by silver zeolites and of the behavior of silver atoms on the reduction stage would be of assistance in optimizing silver mordenite recycle.

  4. Iodine Loading of NO Aged Silver Exchanged Mordenite

    SciTech Connect

    Patton, K. K.; Bruffey, S. H.; Jubin, J. T.; Walker, Jr., J. F.

    2014-09-30

    In an off-gas treatment system for used nuclear fuel processing, a solid sorbent will typically be exposed to a gas stream for months at a time. This gas stream may be at elevated temperature and could contain water vapor, gaseous nitrogen oxides (NO{sub x}), nitric acid vapors, and a variety of other constituents. For this reason, it is important to evaluate the effects of long-term exposure, or aging, on proposed sorbents. Silver exchanged mordenite (AgZ) is being studied at Oak Ridge National Laboratory (ORNL) to determine its iodine sorption capacity after long term exposure to increasingly more complex chemical environments. Studies previously conducted at ORNL investigated the effects of aging reduced silver exchanged mordenite (Ag{sup 0}Z) in dry air, moist air, and NO2. This study investigated the effects of extended exposure to nitric oxide (NO) gas on the iodine capture performance of Ag{sup 0}Z. A deep bed of Ag{sup 0}Z was aged in a 1% nitric oxide (NO) air stream, and portions of the bed were removed at pre-determined intervals. After being removed from the NO stream, each sample was loaded with iodine in a thin bed configuration. These samples were analyzed by neutron activation analysis (NAA) to quantify the iodine content in the sample. Samples were removed at one week and one month. A 78% decrease in sample capacity was seen after one week of exposure, with no further decrease observed after 1 month of aging. The observed loss in capacity is larger in magnitude than previous studies exposing Ag{sup 0}Z to dry air, moist air, or NO2 gas. The aging study was terminated after one month and repeated; this successfully demonstrated the reproducibility of the results.

  5. Equilibrium, kinetic and thermodynamic study of cesium adsorption onto nanocrystalline mordenite from high-salt solution.

    PubMed

    Lee, Keun-Young; Park, Minsung; Kim, Jimin; Oh, Maengkyo; Lee, Eil-Hee; Kim, Kwang-Wook; Chung, Dong-Yong; Moon, Jei-Kwon

    2016-05-01

    In this study, the equilibrium, kinetics and thermodynamics of cesium adsorption by nanocrystalline mordenite were investigated under cesium contamination with high-salt solution, simulating the case of an operation and decommissioning of nuclear facilities or an accident during the processes. The adsorption rate constants were determined using a pseudo second-order kinetic model. The kinetic results strongly demonstrated that the cesium adsorption rate of nano mordenite is extremely fast, even in a high-salt solution, and much faster than that of micro mordenite. In the equilibrium study, the Langmuir isotherm model fit the cesium adsorption data of nano mordenite better than the Freundlich model, which suggests that cesium adsorption onto nano mordenite is a monolayer homogeneous adsorption process. The obtained thermodynamic parameters indicated that the adsorption involved a very stable chemical reaction. In particular, the combination of rapid particle dispersion and rapid cesium adsorption of the nano mordenite in the solution resulted in a rapid and effective process for cesium removal without stirring, which may offer great advantages for low energy consumption and simple operation. PMID:26683820

  6. Aging of Iodine-Loaded Silver Mordenite in NO2

    SciTech Connect

    Bruffey, Stephanie H.; Jubin, Robert Thomas; Patton, Kaara K.; Walker Jr, Joseph Franklin

    2014-04-01

    Used nuclear fuel facilities need to control and minimize radioactive emissions. Off-gas systems are designed to remove radioactive contaminants, such as 85Kr, 14C, 3H, and 129I. In an off-gas system, any capture material will be exposed to a gas stream for months at a time. This gas stream may be at elevated temperature and could contain water, NOx gas, or a variety of other constituents comprising the dissolver off-gas stream in a nuclear fuel reprocessing plant. For this reason, it is important to evaluate the effects of long-term exposure, or aging, on proposed capture materials. One material under consideration is reduced silver mordenite (Ag0Z), which is recognized for its efficient iodine capture properties. Iodine is immobilized on Ag0Z as AgI, a solid with low volatility (m.p. ≥ 500°C). The aim of this study was to determine whether extended aging at elevated temperature in a nominally 2% NO2 environment would result in a loss of immobilized iodine from this material due to either physical or chemical changes that might occur during aging. Charges of iodine-loaded reduced silver mordenite (I2-Ag0Z) were exposed to a 2% NO2 environment for 1, 2, 3, and 4 months at 150°C, then analyzed for iodine losses The aging study was completed successfully. The material did not visibly change color or form. The results demonstrate that no significant iodine loss was observed over the course of 4 months of 2% NO2 aging of I2-Ag0Z at elevated temperature within the margin of error and the variability (~10%) in the loading along the beds. This provides assurance that iodine will remain immobilized on Ag0Z during extended online use in an off-gas capture treatment system. Future tests should expose I2-Ag0Z to progressively more complex feed gases in an effort to accurately replicate the conditions expected in a reprocessing facility.

  7. Impact protection behavior of a mordenite zeolite system

    NASA Astrophysics Data System (ADS)

    Xu, J.; Hu, R.; Chen, X.; Hu, D.

    2016-05-01

    By combining zeolite with water, a novel nanocomposite may exhibit extraordinary capability of energy absorption and impact mitigation. The multiple size of zeolite may lead to simultaneous yet different infiltration behaviors of water molecules, and thus multi-staged energy mitigation characteristics (which may benefit the scope of application). In this study, we investigate the dynamic infiltration behavior of water into mordenite zeolite (MOR) using molecular dynamics (MD) simulations. Thanks to its hydrophobicity and multi pore-sized structure, the MOR system has a decent energy mitigation performance upon high impact speed. Parametric studies are carried out to investigate the effects of various parameters, including the impact speed, mass, and water/zeolite ratio, on energy mitigating characteristics. The MOR/water mixture may perform better at a higher impact energy with higher MOR zeolite-water ratio. Upon unloading, the defiltration of water molecules is faster and more complete at higher impact speed. Results may guide the design and application of the energy mitigation nanosystem.

  8. Adsorption of hexane isomers on ion-exchanged mordenite

    SciTech Connect

    Huddersman, K.

    1996-10-01

    To remove lead from petrol and thereby promote a cleaner environment, other means must be found to keep the octane number or anti-knock qualities of the petrol high. It is found that this can be accomplished by increasing the proportion of highly branched chain hydrocarbon isomers in the fuel. This in turn promotes processes for the separation of the hydrocarbon isomers and in the case of hexane, it is an easy matter to separate out n-hexane from the more substituted isomers but it is difficult to separate out the mono- from the di-branched isomers. This work addresses itself to such challenging separations using modified zeolites as the separating agent, and by studying the heats of sorption of these isomers on zeolites using gas chromatographic techniques to find a trend in the potential abilities of these modified zeolites to effect a good separation. In this work mordenite zeolite was modified by a range of double cation exchanges and the resulting modified zeolites were investigated for their ability to sorb the hexane isomers 3-methylpentane and 2,3-dimethylbutane. These two isomers are closely related in size as they both have the same kinetic diameter of 0.56 nm. In this work only heats of sorption have been investigated and measurement of the diffusion coefficients, which also affect the ability of the modified zeolites to act as good separating agents, is currently under investigation.

  9. Single-site trinuclear copper oxygen clusters in mordenite for selective conversion of methane to methanol

    PubMed Central

    Grundner, Sebastian; Markovits, Monica A.C.; Li, Guanna; Tromp, Moniek; Pidko, Evgeny A.; Hensen, Emiel J.M.; Jentys, Andreas; Sanchez-Sanchez, Maricruz; Lercher, Johannes A.

    2015-01-01

    Copper-exchanged zeolites with mordenite structure mimic the nuclearity and reactivity of active sites in particulate methane monooxygenase, which are enzymes able to selectively oxidize methane to methanol. Here we show that the mordenite micropores provide a perfect confined environment for the highly selective stabilization of trinuclear copper-oxo clusters that exhibit a high reactivity towards activation of carbon–hydrogen bonds in methane and its subsequent transformation to methanol. The similarity with the enzymatic systems is also implied from the similarity of the reversible rearrangements of the trinuclear clusters occurring during the selective transformations of methane along the reaction path towards methanol, in both the enzyme system and copper-exchanged mordenite. PMID:26109507

  10. Single-site trinuclear copper oxygen clusters in mordenite for selective conversion of methane to methanol.

    PubMed

    Grundner, Sebastian; Markovits, Monica A C; Li, Guanna; Tromp, Moniek; Pidko, Evgeny A; Hensen, Emiel J M; Jentys, Andreas; Sanchez-Sanchez, Maricruz; Lercher, Johannes A

    2015-01-01

    Copper-exchanged zeolites with mordenite structure mimic the nuclearity and reactivity of active sites in particulate methane monooxygenase, which are enzymes able to selectively oxidize methane to methanol. Here we show that the mordenite micropores provide a perfect confined environment for the highly selective stabilization of trinuclear copper-oxo clusters that exhibit a high reactivity towards activation of carbon-hydrogen bonds in methane and its subsequent transformation to methanol. The similarity with the enzymatic systems is also implied from the similarity of the reversible rearrangements of the trinuclear clusters occurring during the selective transformations of methane along the reaction path towards methanol, in both the enzyme system and copper-exchanged mordenite. PMID:26109507

  11. Ketene as a Reaction Intermediate in the Carbonylation of Dimethyl Ether to Methyl Acetate over Mordenite.

    PubMed

    Rasmussen, Dominik B; Christensen, Jakob M; Temel, Burcin; Studt, Felix; Moses, Poul Georg; Rossmeisl, Jan; Riisager, Anders; Jensen, Anker D

    2015-06-15

    Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2CO) as a reaction intermediate. The formation of ketene is predicted by detailed DFT calculations and verified experimentally by the observation of doubly deuterated acetic acid (CH2DCOOD), when D2O is introduced in the feed during the carbonylation reaction. PMID:25967363

  12. Characterization of Se-loaded molecular sieves A, X, Y, AlPO-5, and mordenite

    SciTech Connect

    Parise, J.B.; MacDougall, J.E.; Herron, N.; Farlee, R.; Sleight, A.W.; Ying Wang; Bein, T.; Moller, K.; Moroney, L.M.

    1988-01-27

    Selenium has been successfully loaded into molecular sieves A, X, Y, AlPO-5, and mordenite, and the products were characterized by using EXAFS, solid-state NMR, and diffuse-reflectance techniques. This study reveals selenium is predominantly of the trigonal (helical chains) form in all but the A sample, where only the Se/sub 8/-crown ring form is found. A mixture of allotropes and helical chains occupy the large 3D-pore and channel systems of molecular sieves X and Y; however, a single, probably fixed-pitch helical-chain allotrope occupies the more constrained 12-membered-ring channels found in mordenite and AlPO-5. The high degree of order in these last two sieves is reflected in a strong second-shell feature in the EXAFS spectra. 22 refs., 12 figs., 3 tabs.

  13. Elaboration and Characterization of High Silica ZSM-5 and Mordenite Solid Microporous Materials

    NASA Astrophysics Data System (ADS)

    Khemaissia, Sihem; Nibou, Djamel; Amokrane, Samira; Lebaili, Nemcha

    In this study, we were interested to use a hydrothermally method of elaboration of ZSM-5 and Mordenite solid microporous materials. This method is based on crystallization of amorphous gels composed of silicon and aluminium solutions. The elaborations were carried out in stainless steel Teflon lined autoclave over different operation conditions: heating temperature, contact time, pH and agitation of the reactional medium. After crystallization, samples were characterized by several techniques as X ray diffraction, scanning microscopy, infrared spectroscopy. The used method was allowed the obtaining of pure phases of solids belonging to ZSM-5 and mordenite structures respectively. The crystal growth environment during nucleation and crystallization was occurred at the liquid-gel interface in the dispersed gel-solution mixtures. The composition of these structures was found as high silica zeolites.

  14. Optimization of sintered AgI-Mordenite composites for {sup 129}I storage

    SciTech Connect

    Garino, T.J.; Nenoff, T.M.; Rodriguez, M.A.; Mowry, C.D.; Rademacher, D.X.

    2013-07-01

    The thermal processing of a proposed durable waste form for {sup 129}I was investigated. The waste form is a composite with a matrix of low-temperature sintering glass that encapsulates particles of AgI-mordenite. Ag-mordenite, an ion-exchanged zeolite, is being considered as a capture medium for gaseous {sup 129}I{sub 2} as part of a spent nuclear fuel reprocessing scheme under development by the US Department of Energy/Nuclear Energy (NE). The thermal processing of the waste form is necessary to increase the density of the glass matrix by viscous sintering so that the final waste form does not have any open porosity. Other processes that can also occur during the thermal treatment include desorption of chemisorbed I{sub 2}, volatilization of AgI and crystallization of the glass matrix. We have optimized the thermal processing to achieve the desired high density with higher AgI-mordenite loading levels and with minimal loss of iodine. Using these conditions, 625 C. degrees for 20 minutes, the matrix crystallizes to form a eulytite phase. Results of durability tests indicate that the matrix crystallization does not significantly decrease the durability in aqueous environments. (authors)

  15. Studies on the acidity of mordenite and ZSM-5. 1. Determination of Broensted acid site concentrations in mordenite and ZSM-5 by conductometric titration

    SciTech Connect

    Crocker, M.; Herold, R.H.M.; Sonnemans, M.H.W.; Emeis, C.A.; Wilson, A.E.; Moolen, J.N. van der )

    1993-01-14

    The Broensted acidity of H-mordenite and H-ZSM-5 samples of varying proton concentration has been studied using aqueous conductometric titration, IR spectroscopy, and aqueous potentiometric titration. Good agreement is observed between Broensted acid site concentrations determined by conductometric titration and IR measurements, while indirect potentiometric titration affords acid site concentrations consistently lower than those measured using the conductometric technique. This finding is rationalized on the basis that, in a conductometric titration, all the accessible Broensted acid sites are direct;y titrated, whereas in the potentiometric procedure utilized, only those protons which can be ion-exchanged out of the zeolite are titrated. After allowing for the presence of extraframework aluminum in the zeolites (determined by [sup 27]Al NMR), the measured acidity for H-mordenite is found to increase linearly with increasing Al content within the range 0-1.5 mmol Al/g but appears to reach a limiting value at higher Al concentrations. For H-ZSM-5, the experimentally determined number of Broensted acid sites is also found to be linearly dependent on the Al molar fraction within the range measured (0-1.20 mmol Al/g). For both series of zeolite samples, the measured acidity is generally found to be less than the theoretical maximum calculated on the basis of an H[sup +]/Al ratio of 1. 43 refs., 10 figs., 4 tabs.

  16. Solubility and stability of zeolites in aqueous solution: 2. Calcic clinoptilolite and mordenite

    SciTech Connect

    Benning, L.G.; Wilkin, R.T.; Barnes, H.L.

    2000-04-01

    The solubilities of Ca-exchanged clinoptilolite (Cpt-Ca) and Ca-exchanged mordenite (Mor-Ca) have been measured in aqueous solutions between 25 and 275 C and at saturated water vapor pressures. Natural zeolites were cation exchanged to close to Ca end-member composition (90% for Cpt-Ca, and 98% for Mor-Ca). The controlling dissolution reactions are reversible as shown by equilibrium constants calculated for approach from under- and supersaturation. The log K{sub sp} for Cpt-Ca increases from {minus}26.9 at 25 C to a maximum of {minus}16.9 at 275 C, whereas for Mor-Ca the equilibrium constant varies from {minus}25.3 at 25 C to {minus}17.7 at 265 C. The solubilities for both zeolites increase with increasing temperature showing a positive enthalpy for the dissolution reaction. At lower temperatures Cpt-Ca is slightly more soluble than Mor-Ca, which agrees with natural observations where mordenite and clinoptilolite commonly occur together spatially but mordenite is in general the higher-temperature phase. A comparison with other exchanged clinoptilolites indicates that Cpt-Ca is more stable than the Na, K, and Mg varieties. The results demonstrate that the exchanged cation has a large effect on the solubility behavior, and that divalently exchanged varieties are less soluble than monovalent varieties. From the solubility constants, the standard Gibbs free energies of formation for hydrous Cpt-Ca and Mor-Ca at 25 C and 1 bar were determined to be {minus}6,387 {+-} 5 kJ/mol and {minus}6,275 {+-} 7 kJ/mol, respectively. However, compared to the hydration states and the aluminosilicate structure, the effect of the cation on the Gibbs free energies of formation is small.

  17. High-resolution /sup 27/Al NMR study of the states of aluminum atoms in modified natural mordenite

    SciTech Connect

    Il'in, V.G.; Turutina, N.V.; Brei, V.V.; Voloshinets, V.G.; Onishchenko, A.D.

    1987-09-01

    High-resolution /sup 27/Al NMR has been applied to the states of aluminum in modified natural mordenite. Acid treatment of the natural mordenite and heat treatment of the ammonium form alter the coordination state of 6-8% of the aluminum atoms from tetrahedral (in the framework) to octahedral (at the inner surfaces of the zeolite cavities). In that state, the aluminum can exchange with Na/sup +/, NH/sub 4//sup +/, and other cations. This change in coordination state should have a considerable effect on the catalytic parameters of zeolites.

  18. Adsorption of iodine on hydrogen-reduced silver-exchanged mordenite: Experiments and modeling

    DOE PAGESBeta

    Nan, Yue; Tavlarides, Lawrence L.; DePaoli, David W.

    2016-08-03

    The adsorption process of iodine, a major volatile radionuclide in the off-gas streams of spent nuclear fuel reprocessing, on hydrogen-reduced silver-exchanged mordenite (Ag0Z) was studied at the micro-scale. The gas-solid mass transfer and reaction involved in the adsorption process were investigated and evaluated with appropriate models. Optimal conditions for reducing the silver-exchanged mordenite (AgZ) in a hydrogen stream were determined. Kinetic and equilibrium data of iodine adsorption on Ag0Z were obtained by performing single-layer adsorption experiments with experimental systems of high precision at 373–473 K over various iodine concentrations. Results indicate approximately 91% to 97% of the iodine adsorption wasmore » through the silver-iodine reaction. The effect of temperature on the iodine loading capacity of Ag0Z was discussed. In conclusion, the Shrinking Core model describes the data well, and the primary rate controlling mechanisms were macro-pore diffusion and silver-iodine reaction. © 2016 American Institute of Chemical Engineers AIChE J, 2016« less

  19. Mordenite and montmorillonite alteration of glass structures in a rhyolite pipe, northern Black Hills, South Dakota

    SciTech Connect

    Kirchner, J.G. )

    1991-10-01

    Green structures, 0.5 to 1.5 in. across, occur in a Tertiary rhyolite pipe in the northern Black Hills, South Dakota. The structures are of two types: angular to ellipsoidal masses and stretched or smeared structures. Thin section analysis revealed that those of the first type are massive, with no internal structure, and those of the second type are cellular and have classic flame structure characteristics. XRD indicated the composition to be a mixture of secondary mordenite (a zeolite) and montmorillonite. The first type is interpreted to be deuterically altered vitrophyre clasts and the second type to be altered vesicular structures produced by degassing of the magma in the pipe. Chemical analysis of the alteration material indicates a loss of alkalies and silica, with an increase in water, CaO, MgO and ferric iron when compared to the composition of fresh vitrophyre from the same pipe. The changes are in agreement with experimental work on the alteration of rhyolitic glass by a number of researchers. This is the first occurrence of mordenite reported for the Black Hills.

  20. Kinetic and equilibrium studies of the removal of ammonium ions from aqueous solution by rice husk ash-synthesized zeolite Y and powdered and granulated forms of mordenite.

    PubMed

    Yusof, Alias Mohd; Keat, Lee Kian; Ibrahim, Zaharah; Majid, Zaiton Abdul; Nizam, Nik Ahmad

    2010-02-15

    The removal of ammonium from aqueous solutions using zeolite NaY prepared from a local agricultural waste, rice husk ash waste was investigated and a naturally occurring zeolite mordenite in powdered and granulated forms was used as comparison. Zeolite NaY and mordenite were well characterized by powder X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis and the total cation exchange capacity (CEC). CEC of the zeolites were measured as 3.15, 1.46 and 1.34 meq g(-1) for zeolite Y, powdered mordenite and granular mordenite, respectively. Adsorption kinetics and equilibrium data for the removal of NH(4)(+) ions were examined by fitting the experimental data to various models. Kinetic studies showed that the adsorption followed a pseudo-second-order reaction. The equilibrium pattern fits well with the Langmuir isotherm compared to the other isotherms. The monolayer adsorption capacity for zeolite Y (42.37 mg/g) was found to be higher than that powdered mordenite (15.13 mg/g) and granular mordenite (14.56 mg/g). Thus, it can be concluded that the low cost and economical rice husk ash-synthesized zeolite NaY could be a better sorbent for ammonium removal due to its rapid adsorption rate and higher adsorption capacity compared to natural mordenite. PMID:19879040

  1. Pressure-induced penetration of guest molecules in high-silica zeolites: the case of mordenite.

    PubMed

    Arletti, R; Leardini, L; Vezzalini, G; Quartieri, S; Gigli, L; Santoro, M; Haines, J; Rouquette, J; Konczewicz, L

    2015-10-01

    A synthetic high-silica mordenite (HS-MOR) has been compressed in both non-penetrating (silicone oil, s.o.) and penetrating [methanol : ethanol : water (16 : 3 : 1) (m.e.w.), water : ethanol (3 : 1) (w.e.), and ethylene glycol (e.gl.)] pressure transmitting media (PTM). In situ high-pressure (HP) synchrotron X-ray powder diffraction (XRPD) experiments allowed the unit cell parameters to be followed up to 1.6, 1.8, 8.4, and 6.7 GPa in s.o., w.e., m.e.w., and e.gl., respectively. Moreover, e.gl. was also used as a PTM in in situ HP Raman and ex situ IR experiments. The structural refinement of HS-MOR compressed in e.gl. at 0.1 GPa - the lowest investigated pressure - revealed the presence of 3.5 ethylene glycol molecules per unit cell. The infrared spectrum of the recovered sample, after compression to 1 GPa, is consistent with the insertion of ethylene glycol molecules in the pores. XRPD and Raman spectroscopy experiments performed under pressure indicated the insertion of a small number of guest molecules. Ethylene glycol is partially retained inside mordenite upon pressure release. A symmetry lowering was observed in s.o. above 0.8 GPa, while above 1.6 GPa the patterns indicated a rapid loss of long range order. From ambient pressure (Pamb) to 1.6 GPa, a high cell volume contraction (ΔV = -9.5%) was determined. The patterns collected with penetrating PTM suggested the penetration of guest molecules into the porous host matrix, starting from a very low P regime. The entrapment of PTM molecules inside micropores contributes to the stiffening of the structure and, as a consequence, to the decrease of the compressibility with respect to that measured in s.o. From the structural point of view, HS-MOR reacts to compression and to the penetration of different guest species with appropriate framework deformations. Interestingly, ethylene glycol is partially retained inside mordenite upon pressure release, which is of importance for potential

  2. Radioactive iodine capture in silver-containing mordenites through nanoscale silver iodide formation.

    SciTech Connect

    Chapman, K. W.; Chupas, P. J.; Nenoff, T. M.; X-Ray Science Division; SNL

    2010-01-01

    The effective capture and storage of radiological iodine ({sup 129}I) remains a strong concern for safe nuclear waste storage and safe nuclear energy. Silver-containing mordenite (MOR) is a longstanding benchmark for iodine capture; however, the molecular level understanding of this process needed to develop more effective iodine getters has remained elusive. Here we probe the structure and distribution of iodine sorbed by silver-containing MOR using differential pair distribution function analysis. While iodine is distributed between {gamma}-AgI nanoparticles on the zeolite surface and subnanometer {alpha}-AgI clusters within the pores for reduced silver MOR, in the case of unreduced silver-exchanged MOR, iodine is exclusively confined to the pores as subnanometer {alpha}-AgI. Consequently, unreduced silver-containing zeolites may offer a more secure route for radioactive iodine capture, with the potential to more effectively trap the iodine for long-term storage.

  3. Mechanistic differences between methanol and dimethyl ether carbonylation in side pockets and large channels of mordenite.

    PubMed

    Boronat, Mercedes; Martínez, Cristina; Corma, Avelino

    2011-02-21

    The activity and selectivity towards carbonylation presented by Brønsted acid sites located inside the 8MR pockets or in the main 12MR channels of mordenite is studied by means of quantum-chemical calculations, and the mechanistic differences between methanol and DME carbonylation are investigated. The selectivity towards carbonylation is higher inside the 8MR pockets, where the competitive formation of DME and hydrocarbons that finally leads to catalyst deactivation is sterically impeded. Moreover, inclusion of dispersion interactions in the calculations leads to agreement between the calculated activation barriers for the rate determining step and the experimentally observed higher reactivity of methoxy groups located inside the 8MR channels. PMID:21249237

  4. K/AR dating of clinoptilolite, mordenite, and associated clays from Yucca Mountains, Nevada

    SciTech Connect

    WoldeGabriel, G.

    1993-07-01

    Zeolites are abundant in the geologic record in both continental and marine environments. The purpose of the present study is to evaluate the utility of K-bearing zeolites for dating by the K/Ar method to determine the time of zeolite diagenesis at Yucca Mountain, Nevada (Fig. 1). At Yucca Mountain, K-rich clinoptilolite and possibly mordenite are the only potentially K/Ar dateable secondary minerals present in the zeolite-rich tuffs except for some illite/smectites ({ge}10% illite layers) associated with these minerals. Direct dating of K-rich clinoptilolite, the most abundant zeolite in the altered tuffs, is important to delineate zeolite chronology as part of the site characterization of Yucca Mountain.

  5. Correlation of adsorption isotherms of hydrogen isotopes on mordenite adsorbents using reactive vacancy solution theory

    SciTech Connect

    Munakata, K.; Nakamura, A.; Kawamura, Y.

    2015-03-15

    The authors have applied the isotherm equations derived from the reactive vacancy solution theory (RVST) to correlation of experimental and highly non-ideal adsorption isotherms of hydrogen and deuterium on a mordenite adsorbent, and have examined the ability of the isotherm equations to match this correlation. Several isotherm equations such as Langmuir, Freundlich, Toth, Vacancy Solution Theory and so forth were also tested, but they did not work. For the Langmuir-Freundlich equation tests have indicated that its 'ability to correlate' of the adsorption isotherms is not satisfactory. For the multi-site Langmuir-Freundlich (MSLF) equation the correlation of the isotherms appears to be somewhat improved but remains unsatisfactory. The results show that the isotherm equations derived from RVST can better correlate the experimental isotherms.

  6. Direct synthesis of ethanol from dimethyl ether and syngas over combined H-Mordenite and Cu/ZnO catalysts.

    PubMed

    Li, Xingang; San, Xiaoguang; Zhang, Yi; Ichii, Takashi; Meng, Ming; Tan, Yisheng; Tsubaki, Noritatsu

    2010-10-25

    Ethanol was directly synthesized from dimethyl ether (DME) and syngas with the combined H-Mordenite and Cu/ZnO catalysts that were separately loaded in a dual-catalyst bed reactor. Methyl acetate (MA) was formed by DME carbonylation over the H-Mordenite catalyst. Thereafter, ethanol and methanol were produced by MA hydrogenation over the Cu/ZnO catalyst. With the reactant gas containing 1.0% DME, the optimized temperature for the reaction was at 493 K to reach 100% conversion. In the products, the yield of methanol and ethanol could reach 46.3% and 42.2%, respectively, with a small amount of MA, ethyl acetate, and CO(2). This process is environmentally friendly as the main byproduct methanol can be recycled to DME by a dehydration reaction. In contrast, for the physically mixed catalysts, the low conversion of DME and high selectivity of methanol were observed. PMID:20715046

  7. Ethyl tert-butyl ether (ETBE) synthesis on H-Mordenite: Gas-phase kinetics and DRIFTS studies

    SciTech Connect

    Larsen, G.; Lotero, E.; Marquez, M.

    1995-12-01

    The ethyl tert-butyl ether (ETBE) formation between 313 and 363 K over an H-mordenite catalyst was studied in a packed-bed flow catalytic reactor at atmospheric pressure. An activation energy of 82 kJ/mol and reaction orders in isobutene and ethanol of 0.8 and -0.8 were found. In situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was used to study the state of the catalyst under reaction conditions. The IR studies, coupled with the reaction kinetics information, are consistent with the idea that the stability of the H-mordenite catalyst requires the protective action of ethanol to prevent the occurrence of isobutene oligomerization products. The high ethanol concentrations found in the zeolite pores under the temperature and pressure conditions employed is also responsible for reaction inhibition. 27 refs., 13 figs., 1 tab.

  8. DEVELOPMENT OF A HYDROGEN MORDENITE SORBENT FOR THE CAPTURE OF KRYPTON FROM USED NUCLEAR FUEL REPROCESSING OFF-GAS STREAMS

    SciTech Connect

    Mitchell Greenhalgh; Troy G. Garn; Jack D. Law

    2014-04-01

    A novel new sorbent for the separation of krypton from off-gas streams resulting from the reprocessing of used nuclear fuel has been developed and evaluated. A hydrogen mordenite powder was successfully incorporated into a macroporous polymer binder and formed into spherical beads. The engineered form sorbent retained the characteristic surface area and microporosity indicative of mordenite powder. The sorbent was evaluated for krypton adsorption capacities utilizing thermal swing operations achieving capacities of 100 mmol of krypton per kilogram of sorbent at a temperature of 191 K. A krypton adsorption isotherm was also obtained at 191 K with varying krypton feed gas concentrations. Adsorption/desorption cycling effects were also evaluated with results indicating that the sorbent experienced no decrease in krypton capacity throughout testing.

  9. Use of natural mordenite to remove chromium (III) and to neutralize pH of alkaline waste waters.

    PubMed

    Córdova-Rodríguez, Valduvina; Rodríguez-Iznaga, Inocente; Acosta-Chávez, Raquel María; Chávez-Rivas, Fernando; Petranovskii, Vitalii; Pestryakov, Alexey

    2016-01-01

    The natural mordenite from Palmarito de Cauto deposit (PZ), Cuba, was studied in this work as an ion exchanger to remove Cr(3+) cations from alkaline aqueous solutions at different pH and chromium concentrations. The mordenite stability under cyclic treatment processes with alkaline solutions and its capacity to decrease the pH of the solutions was also analyzed. It was shown that PZ removes Cr(3+) ions from alkaline solutions, and it happens independently of the starting chromium concentration and the pH of the exchange solution used. This material has an important neutralizing effect on alkaline solutions, expressed in a significant pH decrease from the early stages of the treatments. For solutions with initial pH equal to 11, it decreases to a value of around seven. The stability of this material is not affected significantly after continuous cyclic treatment with NaOH solution, which shows that mordenite, in particular from Palmarito de Cauto deposit, has high stability in alkaline solutions. The results are important as they suggest that natural zeolites may be of interest in treatments of alkaline industrial waste effluents. PMID:26818904

  10. Expanded Analysis of Hot Isostatic Pressed Iodine-Loaded Silver-Exchanged Mordenite

    SciTech Connect

    Jubin, R. T.; Bruffey, S. H.; Patton, K. K.

    2014-09-30

    Reduced silver-exchanged mordenite (Ag0Z) is being evaluated as a potential material to control the release of radioactive iodine that is released during the reprocessing of used nuclear fuel into the plant off-gas streams. The purpose of this study was to determine if hot pressing could directly convert this iodine loaded sorbent into a waste form suitable for long-term disposition. The minimal pretreatment required for production of pressed pellets makes hot pressing a technically and economically desirable process. Initial scoping studies utilized hot uniaxial pressing (HUPing) to prepare samples of non-iodine-loaded reduced silver exchanged mordenite (Ag0Z). The resulting samples were very fragile due to the low pressure (~ 28 MPa) used. It was recommended that hot isostatic pressing (HIPing), performed at higher temperatures and pressures, be investigated. HIPing was carried out in two phases, with a third and final phase currently underway. Phase I evaluated the effects of pressure and temperature conditions on the manufacture of a pressed sample. The base material was an engineered form of silver zeolite. Six samples of Ag0Z and two samples of I-Ag0Z were pressed. It was found that HIPing produced a pressed pellet of high density. Analysis of each pressed pellet by scanning electron microscopy-energy dispersive spectrophotometry (SEM-EDS) and X-ray diffraction (XRD) demonstrated that under the conditions used for pressing, the majority of the material transforms into an amorphous structure. The only crystalline phase observed in the pressed Ag0Z material was SiO2. For the samples loaded with iodine (I-Ag0Z) iodine was present as AgI clusters at low temperatures, and transformed into AgIO4 at high temperatures. Surface mapping and EDS demonstrate segregation between silver iodide phases and silicon dioxide phases. Based on the results of the Phase I study, an expanded test matrix was developed to examine the effects of multiple source materials, compositional

  11. Diffusional analysis of the adsorption of methyl iodide on silver exchanged mordenite

    SciTech Connect

    Jubin, R.T.; Counce, R.M.

    1997-08-01

    The removal of organic iodides from off-gas streams is an important step in controlling the release of radioactive iodine to the environment during the treatment of radioactive wastes or the processing of some irradiated materials. Nine-well accepted mass transfer models were evaluated for their ability to adequately explain the observed CH{sub 3}I uptake behavior onto the Ag{degrees}Z. Linear and multidimensional regression techniques were used to estimate the diffusion constants and other model parameters, which then permitted the selection of an appropriate mass transfer model. Although a number of studies have been conducted to evaluate the loading of both elemental and methyl iodide on silver-exchanged mordenite, these studies focused primarily on the macro scale (deep bed) while evaluating the material under a broad range of process conditions and contaminants for total bed loading at the time of breakthrough. A few studies evaluated equilibrium or maximum loading. Thus, to date, only bulk loading data exist for the adsorption of CH{sub 3}I onto Ag{degrees}Z. Hence this is believed to be the first study to quantify the controlling mass transfer mechanisms of this process, It can be concluded from the analysis of the experimental data obtained by the {open_quotes}single-pellet{close_quotes} type experiments and for the process conditions used in this study that the overall mass transfer rate associated with the adsorption of CH{sub 3}I onto Ag{degrees}Z is affected by both micropore and macropore diffusion. The macropore diffusion rate was significantly faster than the micropore diffusion, resulting in a two-step adsorption behavior which was adequately modeled by a bimodal pore distribution model. The micropore diffusivity was determined to be on the order of 2 x 10{sup -14} cm{sup 2}/s. The system was also shown to be isothermal under all conditions of this study. 21 refs., 6 figs., 8 tabs.

  12. A DFT investigation of the adsorption of iodine compounds and water in H-, Na-, Ag-, and Cu- mordenite

    NASA Astrophysics Data System (ADS)

    Chibani, Siwar; Chebbi, Mouheb; Lebègue, Sébastien; Bučko, Tomáš; Badawi, Michael

    2016-06-01

    The potential use of some cation-exchanged mordenite (H+, Na+, Cu+, and Ag+) as a selective adsorbent for volatile iodine species (ICH3 and I2), which can be released during a nuclear accident together with a steam carrier gas, is investigated using density functional theory. It is found that in the case of Cu-MOR and Ag-MOR, the absolute values of interaction energies of ICH3 and I2 are higher than that of water which indicates that these forms of zeolite could be suitable for selective adsorption of iodine species. In contrast, the H-MOR and Na-MOR are found to be unsuitable for this purpose. A systematic investigation of all adsorption sites allowed us to analyze the structural effects affecting the adsorption behavior. For the Ag-MOR and Cu-MOR zeolites, the iodine compounds are adsorbed preferentially in the large channel of mordenite (main channel) while water prefers the small channel or the side pocket where it forms stronger hydrogen bonds. The factors governing the interaction energies between the cationic sites and the different molecules are analyzed and the important role of van der Waals interactions in these systems is highlighted.

  13. Development and evaluation of a silver mordenite composite sorbent for the partitioning of xenon from krypton in gas compositions

    SciTech Connect

    Garn, Troy G.; Greenhalgh, Mitchell; Law, Jack D.

    2015-12-22

    A new engineered form composite sorbent for the selective separation of xenon from krypton in simulant composition off-gas streams resulting from the reprocessing of used nuclear fuel has been developed and evaluated. A sodium mordenite powder was incorporated into a macroporous polymer binder, formed into spherical beads and successfully converted to a 9 wt.% silver form composite sorbent. The final engineered form sorbent retained the characteristic surface area indicative of sodium mordenite powder. The sorbent was evaluated for xenon adsorption potential with capacities measured as high as 30 millimoles of xenon per kilogram of sorbent achieved at ambient temperature and 460 millimoles of xenon per kilogram sorbent at 220 K. Xenon/krypton selectivity was calculated to be 22.4 with a 1020 µL/L xenon, 150 µL/L krypton in a balance of air feed gas at 220 K. Furthermore, adsorption/desorption thermal cycling effects were evaluated with results indicating sorbent performance was not significantly impacted while undergoing numerous adsorption/desorption thermal cycles.

  14. A DFT investigation of the adsorption of iodine compounds and water in H-, Na-, Ag-, and Cu- mordenite.

    PubMed

    Chibani, Siwar; Chebbi, Mouheb; Lebègue, Sébastien; Bučko, Tomáš; Badawi, Michael

    2016-06-28

    The potential use of some cation-exchanged mordenite (H(+), Na(+), Cu(+), and Ag(+)) as a selective adsorbent for volatile iodine species (ICH3 and I2), which can be released during a nuclear accident together with a steam carrier gas, is investigated using density functional theory. It is found that in the case of Cu-MOR and Ag-MOR, the absolute values of interaction energies of ICH3 and I2 are higher than that of water which indicates that these forms of zeolite could be suitable for selective adsorption of iodine species. In contrast, the H-MOR and Na-MOR are found to be unsuitable for this purpose. A systematic investigation of all adsorption sites allowed us to analyze the structural effects affecting the adsorption behavior. For the Ag-MOR and Cu-MOR zeolites, the iodine compounds are adsorbed preferentially in the large channel of mordenite (main channel) while water prefers the small channel or the side pocket where it forms stronger hydrogen bonds. The factors governing the interaction energies between the cationic sites and the different molecules are analyzed and the important role of van der Waals interactions in these systems is highlighted. PMID:27369531

  15. Development and evaluation of a silver mordenite composite sorbent for the partitioning of xenon from krypton in gas compositions

    DOE PAGESBeta

    Garn, Troy G.; Greenhalgh, Mitchell; Law, Jack D.

    2015-12-22

    A new engineered form composite sorbent for the selective separation of xenon from krypton in simulant composition off-gas streams resulting from the reprocessing of used nuclear fuel has been developed and evaluated. A sodium mordenite powder was incorporated into a macroporous polymer binder, formed into spherical beads and successfully converted to a 9 wt.% silver form composite sorbent. The final engineered form sorbent retained the characteristic surface area indicative of sodium mordenite powder. The sorbent was evaluated for xenon adsorption potential with capacities measured as high as 30 millimoles of xenon per kilogram of sorbent achieved at ambient temperature andmore » 460 millimoles of xenon per kilogram sorbent at 220 K. Xenon/krypton selectivity was calculated to be 22.4 with a 1020 µL/L xenon, 150 µL/L krypton in a balance of air feed gas at 220 K. Furthermore, adsorption/desorption thermal cycling effects were evaluated with results indicating sorbent performance was not significantly impacted while undergoing numerous adsorption/desorption thermal cycles.« less

  16. Hydrothermal convection and mordenite precipitation in the cooling Bishop Tuff, California, USA

    NASA Astrophysics Data System (ADS)

    Randolph-Flagg, N. G.; Breen, S. J.; Hernandez, A.; Self, S.; Manga, M.

    2014-12-01

    We present field observations of erosional columns in the Bishop Tuff and then use laboratory results and numerical models to argue that these columns are evidence of relict convection in a cooling ignimbrite. Many square kilometers of the Bishop Tuff have evenly-spaced, vertical to semi-vertical erosional columns, a result of hydrothermal alteration. These altered regions are more competent than the surrounding tuff, are 0.1-0.7 m in diameter, are separated by ~ 1 m, and in some cases are more than 8 m in height. JE Bailey (U. of Hawaii, dissertation, 2005) suggested that similar columns in the Bandelier Tuff were formed when slumping allowed water to pool at the surface of the still-cooling ignimbrite. As water percolated downward it boiled generating evenly spaced convection cells similar to heat pipes. We quantify this conceptual model and apply it the Bishop Tuff to understand the physics within ignimbrite-borne hydrothermal systems. We use thin sections to measure changing porosity and use scanning electron microscope (SEM) and x-ray diffraction (XRD) analyses to show that pore spaces in the columns are cemented by the mineral mordenite, a low temperature zeolite that precipitates between 120-200 oC (Bish et al., 1982), also found in the Bandelier Tuff example. We then use scaling to show 1) that water percolating into the cooling Bishop Tuff would convect and 2) that the geometry and spacing of the columns is predicted by the ignimbrite temperature and permeability. We use the computer program HYDROTHERM (Hayba and Ingebritsen, 1994; Kipp et al., 2008) to model 2-phase convection in the Bishop Tuff. By systematically changing permeability, initial temperature, and topography we can identify the pattern of flows that develop when the ignimbrite is cooled by water from above. Hydrothermally altered columns in ignimbrite are the natural product of coupled heat, mass, and chemical transport and have similarities to other geothermal systems, economic ore deposits

  17. Impact of Pretreatment and Aging on the Iodine Capture Performance of Silver-Exchanged Mordenite - 12314

    SciTech Connect

    Jubin, R.T.; Ramey, D.W.; Spencer, B.B.; Anderson, K.K.; Robinson, S.M.

    2012-07-01

    Volatile gas emissions from a nuclear fuel recycle facility in the United States are governed by several key regulations, including 10 CFR 20, 40 CFR 61, and 40 CFR 190. Under 40 CFR 190, the total quantity of iodine that may be released to the environment from the entire fuel cycle is limited to 5 millicuries of I-129 per gigawatt-year of electrical energy produced by the fuel cycle. With a reasonable engineering margin, an iodine decontamination factor (DF) of approximately 1000 will be required for the complete fuel cycle. Off-gas treatment in a fuel reprocessing plant must address several gas streams containing iodine, among a number of volatile radionuclides. Past research and developmental activities identified silver-exchanged mordenite (AgZ) as a very promising sorbent based on its acid resistance, relatively high iodine and methyl iodide capacity, and high achievable DF. Recent studies at ORNL have focused on the impacts of long-term exposure to simulated off-gas streams (aging) and pretreatment on the iodine adsorption performance of hydrogen-reduced silver-exchanged mordenite (Ag{sup 0}Z). Experiments were conducted to determine the effects of long-term exposure to both dry and moist air on the iodine sorption capacity of Ag{sup 0}Z. The data indicates that aging reduces the capacity of Ag{sup 0}Z, which must be accounted for to prevent degradation of DF. Because of its high acid resistance, a AgZ sorbent has been selected specifically for application in treating off-gas streams containing iodine. While extensive tests have been conducted in the United States on a form of this sorbent, the specific material previously tested is no longer commercially available and similar materials are currently being evaluated. As part of this evaluation, tests were conducted to determine the iodine sorption properties of this replacement media and the effects of long-term (up to 6 months) exposure to simulated off-gas streams. The ultimate goal is to develop an

  18. Enzyme-like specificity in zeolites: a unique site position in mordenite for selective carbonylation of methanol and dimethyl ether with CO.

    PubMed

    Boronat, Mercedes; Martínez-Sánchez, Cristina; Law, David; Corma, Avelino

    2008-12-01

    The mechanism of methanol carbonylation at different positions of zeolite MOR is investigated by quantum-chemical methods in order to discover which are the active sites that can selectively catalyze the desired reaction. It is shown that when methanol carbonylation competes with hydrocarbon formation, the first reaction occurs preferentially within 8MR channels. However, the unique selectivity for the carbonylation of methanol and dimethyl ether in mordenite is not only due to the size of the 8MR channel: neither process occurs equally at the two T3-O31 and T3-O33 positions. We show that only the T3-O33 positions are selective and that this selectivity is due to the unusual orientation of the methoxy group in relation to the 8MR channel (parallel to the cylinder axis). Only in this situation does the transition state for the attack of CO fit perfectly in the 8MR channel, while the reaction with methanol or DME is sterically impeded. This result explains why T3-O31, while also located in the 8MR channel of mordenite, is not as selective as the T3-O33 position and why ferrierite, although it contains 8MR channels, is less selective than mordenite. The competing effect of water is explained at the molecular level, and the molecular microkinetic reaction model has been established. PMID:18986144

  19. Fourier transform infrared spectroscopic study of the adsorption of CO and nitriles on Na-mordenite: evidence of a new interaction.

    PubMed

    Salla, Isabel; Montanari, Tania; Salagre, Pilar; Cesteros, Yolanda; Busca, Guido

    2005-01-20

    The low temperature adsorption of CO and the room temperature adsorption of acetonitrile, propionitrile, isobutyronitrile, pivalonitrile, benzonitrile, and o-toluonitrile on Na-mordenite (NaMOR) have been investigated by Fourier transform infrared (FT-IR) spectroscopy. The results have been compared with analogous experiments performed on H-mordenite, Na-X zeolite, and Na-silica-alumina. The Na distribution in NaMOR has also been investigated by X-ray diffraction and far-IR spectroscopy. The conclusions are that Na+ ion distribution is essentially random and that, together with the well-known interaction of the probes with Na+ ions in the side pockets and the main channels, a stronger additional interaction occurs in all cases. This new interaction is likely multiple, involving either more Na+ ions or Na and oxygen species. This interaction is more pronounced with the hindered nitriles, whose access at the main channels is likely forbidden. This suggests that this interaction, which is also observed on Na-X zeolites but not with Na-silica-alumina, occurs at the external mouths of the mordenite channels. PMID:16866459

  20. Effects of ceria modification of H-mordenite on the shape-selective alkylation of biphenyl and naphthalene

    SciTech Connect

    Matsuzaki, T.; Hanaoka, T.; Kim, J.H.; Nakajima, K.; Tawada, S.; Kubota, Y.; Sugi, Y.

    1999-07-01

    The effects of the modification with ceria to H-mordenite (HM, SiO{sub 2}/Al{sub 2}O{sub 3} = 128) were investigated for the shape-selective alkylation of biphenyl and naphthalene. Such a large amount as 10--50 wt% of ceria-modification was revealed to be effective for the deactivation of external acid sites of HM. In the isopropylation of biphenyl (BP), the selectivity of 4,4{prime}-diisopropylbiphenyl (4,4{prime}-DIPB) kept high over Ce-modified HM even at a high reaction temperature at which temperature the selectivity fell down to quite low over unmodified HM. The effect was due to the prevention of the isomerization of 4,4{prime}-DIPB which occurred on the HM external acid site. The selectivity of 2,6-diisopropynaphthalene (2,6-DIPN) in the isopropylation of naphthalene (NP) was enhanced by the modification without significant decrease of catalytic activity: the highest selectivity for 2,6-DIPN was achieved up to 70% over HM with 30 wt% of cerium. The enhancement of the selectivities of 2,6-DIPN and 4,4{prime}-DIPB by ceria-modification is ascribed to the decrease of external acid sites to catalyze non-regioselective alkylation and the isomerization of products.

  1. Silver-mordenite for radiologic gas capture from complex streams. Dual catalytic CH3I decomposition and I confinement

    DOE PAGESBeta

    Nenoff, Tina M.; Rodriguez, Mark A.; Soelberg, Nick R.; Chapman, Karena W.

    2014-05-09

    The selective capture of radiological iodine (129I) is a persistent concern for safe nuclear energy. In these nuclear fuel reprocessing scenarios, the gas streams to be treated are extremely complex, containing several distinct iodine-containing molecules amongst a large variety of other species. Silver-containing mordenite (MOR) is a longstanding benchmark for radioiodine capture, reacting with molecular iodine (I2) to form AgI. However the mechanisms for organoiodine capture is not well understood. Here we investigate the capture of methyl iodide from complex mixed gas streams by combining chemical analysis of the effluent gas stream with in depth characterization of the recovered sorbent.more » Tools applied include infrared spectroscopy, thermogravimetric analysis with mass spectrometry, micro X-ray fluorescence, powder X-ray diffraction analysis, and pair distribution function analysis. Moreover, the MOR zeolite catalyzes decomposition of the methyl iodide through formation of surface methoxy species (SMS), which subsequently reacts with water in the mixed gas stream to form methanol, and with methanol to form dimethyl ether, which are both detected downstream in the effluent. The liberated iodine reacts with Ag in the MOR pore to the form subnanometer AgI clusters, smaller than the MOR pores, suggesting that the iodine is both physically and chemically confined within the zeolite.« less

  2. Silver-Mordenite for Radiologic Gas Capture from Complex Streams: Dual Catalytic CH3I Decomposition and I Confinement

    SciTech Connect

    Tina M. Nenoff; Mark Rodriguez; Nick Soelberg; Karena W. Chapman

    2014-12-01

    The effective capture and storage of radiological iodine (129I) remains a strong concern for safe nuclear waste storage and safe nuclear energy. Silver-containing mordenite (MOR) is a longstanding benchmark for iodine capture. In nuclear fuel reprocessing scenarios, complex gas streams will be present and the need for high selectivity of all iodine containing compounds is of the utmost importance for safety and the environment. In particular, a molecular level understanding of the sorption of organic iodine compounds is not well understood. Here we probe the structure and distribution of methyl iodide sorbed by silver-containing MOR using a combination of crystallographic and materials characterization techniques including: infrared spectroscopy, thermogravimetric analysis with mass spectrometry, Micro-X-ray Fluorescence, powder X-ray diffraction analysis, and pair distribution function analysis. The iodine is captured inside the MOR pore in the form of AgI nanoparticles, that is consistent with the pores sizes of the MOR, indicating that the molecule is both physically and chemically captured in the Ag-MOR. The organic component is surface catalyzed by the zeolite via the formation of Surface Methoxy Species (SMS) that result in downstream organics of dimethyl ether and methanol formation.

  3. Rationalizing Inter- and Intracrystal Heterogeneities in Dealuminated Acid Mordenite Zeolites by Stimulated Raman Scattering Microscopy Correlated with Super-resolution Fluorescence Microscopy

    PubMed Central

    2014-01-01

    Dealuminated zeolites are widely used acid catalysts in research and the chemical industry. Bulk-level studies have revealed that the improved catalytic performance results from an enhanced molecular transport as well as from changes in the active sites. However, fully exploiting this information in rational catalyst design still requires insight in the intricate interplay between both. Here we introduce fluorescence and stimulated Raman scattering microscopy to quantify subcrystal reactivity as well as acid site distribution and to probe site accessibility in the set of individual mordenite zeolites. Dealumination effectively introduces significant heterogeneities between different particles and even within individual crystals. Besides enabling direct rationalization of the nanoscale catalytic performance, these observations reveal valuable information on the industrial dealumination process itself. PMID:25402756

  4. Review of the thermal stability and cation exchange properties of the zeolite minerals clinoptilolite, mordenite, and analcime; applications to radioactive waste isolation in silicic tuff

    SciTech Connect

    Smyth, J.R.; Caporuscio, F.A.

    1981-06-01

    Silicic tuffs of the southern Great Basin and basalts of the Columbia River Plateau are under investigation as potential host rocks for high- and intermediate-level radioactive wastes. Nonwelded and partially welded tuffs may contain major amounts (> 50%) of the zeolite minerals clinoptilolite, mordenite, and analcime. Densely welded tuffs and some basalt flows may contain clinoptilolite as fracture filling that limits the permeability of these rocks. The cation exchange properties of these zeolite minerals allow them to pose a formidable natural barrier to the migration of cationic species of various radionuclides in aqueous solutions. However, these minerals are unstable at elevated temperatures and at low water-vapor pressures and may break down either by reversible dehydration or by irreversible mineralogical reactions. All the breakdown reactions occurring at increased temperature involve a net volume reduction and evolution of fluids. Thus, they may provide a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere. These reactions may be avoided by keeping zeolite-bearing horizons saturated with water and below about 85{sup 0}C. This may restrict allowable gross thermal loadings in waste repositories in volcanic rocks.

  5. Silver-mordenite for radiologic gas capture from complex streams. Dual catalytic CH3I decomposition and I confinement

    SciTech Connect

    Nenoff, Tina M.; Rodriguez, Mark A.; Soelberg, Nick R.; Chapman, Karena W.

    2014-05-09

    The selective capture of radiological iodine (129I) is a persistent concern for safe nuclear energy. In these nuclear fuel reprocessing scenarios, the gas streams to be treated are extremely complex, containing several distinct iodine-containing molecules amongst a large variety of other species. Silver-containing mordenite (MOR) is a longstanding benchmark for radioiodine capture, reacting with molecular iodine (I2) to form AgI. However the mechanisms for organoiodine capture is not well understood. Here we investigate the capture of methyl iodide from complex mixed gas streams by combining chemical analysis of the effluent gas stream with in depth characterization of the recovered sorbent. Tools applied include infrared spectroscopy, thermogravimetric analysis with mass spectrometry, micro X-ray fluorescence, powder X-ray diffraction analysis, and pair distribution function analysis. Moreover, the MOR zeolite catalyzes decomposition of the methyl iodide through formation of surface methoxy species (SMS), which subsequently reacts with water in the mixed gas stream to form methanol, and with methanol to form dimethyl ether, which are both detected downstream in the effluent. The liberated iodine reacts with Ag in the MOR pore to the form subnanometer AgI clusters, smaller than the MOR pores, suggesting that the iodine is both physically and chemically confined within the zeolite.

  6. Molecular adsorption and metal-support interaction for transition-metal clusters in zeolites: NO adsorption on Pd(n) (n=1-6) clusters in mordenite.

    PubMed

    Grybos, Robert; Benco, Lubomir; Bucko, Tomas; Hafner, Jürgen

    2009-03-14

    The adsorption of NO molecules on Pd(n) clusters of varying size (n=1-6) located in the main channel of mordenite and the interaction of the metallic clusters with the zeolitic framework were investigated using ab initio density-functional calculations under periodic boundary conditions. The supported clusters are created by binding Pd(n) (2+) cations to the inner cavity of a deprotonated Al-exchanged zeolite with an Al/Si ratio of 1/11, such that a charge-neutral system is created. Compared to the highly symmetric structures of the gas-phase clusters, the clusters bound to the zeolitic framework undergo appreciable geometric distortions lowering their symmetry. The distortions are induced by strong interactions with "activated" framework oxygens located close to the charge-compensating Al/Si substitution sites, but the cluster forms also weaker bonds to "nonactivated" oxygen atoms. The interaction with the framework also affects the electronic and magnetic properties of the clusters. While in the gas phase all clusters (except the isolated Pd atom with a closed d(10) ground state) have a paramagnetic moment of 2mu(B), in the zeolite clusters with two to four atoms have zero magnetic moment, while the Pd(5) cluster has a magnetic moment of 2mu(B) and for the Pd(6) cluster, it is even enhanced to 4 mu(B) (but the magnetic energy differences relative to low-spin configurations are modest). Analysis of the magnetization densities shows that in all clusters with zero total moment (singlet ground state), there are sites with excess spin densities of opposite sign. The influence of the cluster-support interaction on the chemical properties of the clusters has been tested by the adsorption of NO molecules. The results demonstrate the interplay between the molecule-cluster and cluster-framework interactions, which can lead to an increase or decrease in the adsorption energy compared to NO on a gas-phase cluster. While on the gas-phase cluster adsorption in low

  7. Molecular adsorption and metal-support interaction for transition-metal clusters in zeolites: NO adsorption on Pdn (n=1-6) clusters in mordenite

    NASA Astrophysics Data System (ADS)

    Grybos, Robert; Benco, Lubomir; Bučko, Tomas; Hafner, Jürgen

    2009-03-01

    The adsorption of NO molecules on Pdn clusters of varying size (n =1-6) located in the main channel of mordenite and the interaction of the metallic clusters with the zeolitic framework were investigated using ab initio density-functional calculations under periodic boundary conditions. The supported clusters are created by binding Pdn2+ cations to the inner cavity of a deprotonated Al-exchanged zeolite with an Al/Si ratio of 1/11, such that a charge-neutral system is created. Compared to the highly symmetric structures of the gas-phase clusters, the clusters bound to the zeolitic framework undergo appreciable geometric distortions lowering their symmetry. The distortions are induced by strong interactions with "activated" framework oxygens located close to the charge-compensating Al/Si substitution sites, but the cluster forms also weaker bonds to "nonactivated" oxygen atoms. The interaction with the framework also affects the electronic and magnetic properties of the clusters. While in the gas phase all clusters (except the isolated Pd atom with a closed d10 ground state) have a paramagnetic moment of 2μB, in the zeolite clusters with two to four atoms have zero magnetic moment, while the Pd5 cluster has a magnetic moment of 2μB and for the Pd6 cluster, it is even enhanced to 4μB (but the magnetic energy differences relative to low-spin configurations are modest). Analysis of the magnetization densities shows that in all clusters with zero total moment (singlet ground state), there are sites with excess spin densities of opposite sign. The influence of the cluster-support interaction on the chemical properties of the clusters has been tested by the adsorption of NO molecules. The results demonstrate the interplay between the molecule-cluster and cluster-framework interactions, which can lead to an increase or decrease in the adsorption energy compared to NO on a gas-phase cluster. While on the gas-phase cluster adsorption in low-coordination sites (vertex or

  8. The growth of zeolites A, X and mordenite in space

    NASA Technical Reports Server (NTRS)

    Sacco, Albert, Jr.; Bac, N.; Coker, E. N.; Dixon, A. G.; Warzywoda, J.; Thompson, R. W.

    1994-01-01

    Zeolites are a class of crystalline aluminosilicate materials that form the backbone of the chemical process industry worldwide. They are used primarily as adsorbents and catalysts and support to a significant extent the positive balance of trade realized by the chemical industry in the United States (around $19 billion in 1991). The magnitude of their efforts can be appreciated when one realizes that since their introduction as 'cracking catalysts' in the early 1960's, they have saved the equivalent of 60 percent of the total oil production from Alaska's North Slope. Thus the performance of zeolite catalysts can have a profound effect on the U.S. economy. It is estimated that a 1 percent increase in yield of the gasoline fraction per barrel of oil would represent a savings of 22 million barrels of crude oil per year, representing a reduction of $400 million in the United States' balance of payments. Thus any activity that results in improvement in zeolite catalyst performance is of significant scientific and industrial interest. In addition, due to their 'stability,' uniformity, and, within limits, their 'engineerable' structures, zeolites are being tested as potential adsorbents to purify gases and liquids at the parts-per-billion levels needed in today's electronic, biomedical, and biotechnology industries and for the environment. Other exotic applications, such as host materials for quantum-confined semiconductor atomic arrays, are also being investigated. Because of the importance of this class of material, extensive efforts have been made to characterize their structures and to understand their nucleation and growth mechanisms, so as to be able to custom-make zeolites for a desired application. To date, both the nucleation mechanics and chemistry (such as what are the 'key' nutrients) are, as yet, still unknown for many, if not all, systems. The problem is compounded because there is usually a 'gel' phase present that is assumed to control the degree of supersaturation, and this gel undergoes a continuous 'polymerization' type reaction during nucleation and growth. Generally, for structure characterization and diffusion studies, which are useful in evaluating zeolites for improving yield in petroleum refining as well as for many of the proposed new applications (e.g., catalytic membranes, molecular electronics, chemical sensors) large zeolites (greater than 100 to 1000 times normal size) with minimum lattice defects are desired. Presently, the lack of understanding of zeolite nucleation and growth precludes the custom design of zeolites for these or other uses. It was hypothesized that the microgravity levels achieved in an orbiting spacecraft could help to isolate the possible effects of natural convection (which affects defect formation) and minimize sedimentation, which occurs since zeolites are twice as dense as the solution from which they are formed. This was expected to promote larger crystals by allowing growing crystals a longer residence time in a high-concentration nutrient field. Thus it was hypothesized that the microgravity environment of Earth orbit would allow the growth of large, more defect-free zeolite crystals in high yield.

  9. Crystal Structure of MCM-71 - a New Zeolite in the Mordenite Group

    SciTech Connect

    Dorset, D.; Roth, W; Kennedy, G; Dhingra, S

    2008-01-01

    The crystal structure of the aluminosilicate, MCM-71, was determined by a match of the powder X-ray diffraction pattern to one calculated from a theoretically predicted framework model. The unit cell contains 48 T-sites and 96 framework oxygens, where T = 41.1 Si, 6.9 Al. It crystallizes in space group Cmca, a = 7.4422(2), b = 18.5324(5), c = 19.1877(5) {angstrom}. The framework contains an elliptical 10-membered ring channel (4.3 x 6.5 {angstrom}) and an orthogonal undulating 8-membered ring channel (3.6 x 4.7 {angstrom}) to constitute a two-dimensional network of channels. Considering the aluminosilicate framework as a silicate, the crystal density is 1.77 g/cm{sup 3} and the T-site framework density is 17.8 T/1000 A{sup 3}. The structure was refined against Debye-Scherrer and Bragg-Brentano powder synchrotron data by the Rietveld procedure. While non-framework oxygen atoms, consistent with water content, could be justified by TGA measurements, it was not possible to derive an accurate extra-framework model using synchrotron data from hydrated specimens. Refinement against powder data from an anhydrous specimen subsequently detected the presence of extra-framework aluminum, identified also by solid state NMR measurements.

  10. Determination of Desorbed Species During Heating of AgI-Mordenite Provided by ORNL

    SciTech Connect

    Croes, Kenneth James; Garino, Terry J.; Mowry, Curtis D.; Nenoff, Tina M.

    2015-12-15

    This study is focused on describing the desorbed off gases due to heating of the AgIMordenite (MOR) produced at ORNL for iodine (I2) gas capture from nuclear fuel aqueous reprocessing. In particular, the interest is for the incorporation of the AgI-MOR into a waste form, which might be the Sandia developed, low temperature sintering, Bi-Si oxide based, Glass Composite Material (GCM). The GCM has been developed as a waste form for the incorporation any oxide based getter material. In the case where iodine may be released during the sintering process of the GCM, additional Ag flake is added as further insurance in total iodine capture and retention. This has been the case for the incorporated ORNL developed AgIMOR. Thermal analysis studies were carried out to determine off gasing processes of ORNL AgIMOR. Independent of sample size, ~7wt% of total water is desorbed by 225°C. This includes both bulk surface and occluded water, and are monitored as H2O and OH. Of that total, ~5.5wt% is surface water which is removed by 125°C, and 1.5wt% is occluded (in zeolite pore) water. Less than ~1 wt% total water continues to desorb, but is completely removed by 500°C. Above 300°C, the detectable remaining desorbing species observed are iodine containing compounds, including I and I2.

  11. Zeolite shape selectivity in the uptake of uranium from solutions

    SciTech Connect

    Ingram, C.W.; Szostak, R.; Cleare, K.

    1996-12-31

    Various synthetic zeolites (KL, LZY, 13X, and mordenite), as well as a natural zeolite (clinoptilolite) were evaluated for the uptake of uranium from solution. Mordenite, LZY and KL were most effective for uranium uptake. The relative effectiveness of the zeolites was a function of their pore dimensions, chemical compositions and cation concentration. Mordenite showed superior performance to a clay-soil for uranium uptake. With time, initially sorbed uranium later re-dissolve from the clay, but remained anchored in the matrix of the zeolite. Mordenite therefore demonstrated potential for use as an in situ trap for preventing uranium migration in soils.

  12. Magnetic and Mössbauer study of metal-zeolite interaction in catalysts

    NASA Astrophysics Data System (ADS)

    Pannaparayil, Thomas; Oskooie-Tabrizi, M.; Lo, C.; Mulay, L. N.; Melson, G. A.; Rao, V. U. S.

    1984-03-01

    Molecular sieve aluminosilicates, such as ZSM-5 and mordenite, when impregnated with highly dispersed Fe, yield catalysts for the selective conversion of coal-derived syngas (CO+H2) to liquid hydrocarbon fuels. Fe performs the primary Fischer-Tropsch (FT) syngas to yield light olefins which are converted by the acidic (H+) and shape-selective function of the zeolite to high octane gasoline components. The physical aspects of the Fe-mordenite interaction studied by magnetic measurements, Mössbauer, and IR spectroscopy are reported and correlations with the catalytic properties are drawn. Mordenite samples with [SiO2/Al2O3] ratio in the range 12 - 60 were impregnated with 15 wt. % Fe using Fe3(CO)12; decarbonylation yielded superparamagmetic dispersions of γ-Fe2O3, in the range 1.4-5.0 nm; the smallest particles were obtained for a ratio=17. Hydrogen chemisorption also revealed a similar trend in Fe dispersions. No samples, other than the one with a ratio=60 and containing the largest particles could be carbided under usual conditions. The acidity of the mordenite and the aromatics fraction in liquid hydrocarbons from syngas conversion also showed maxima at a ratio=17. The presence of a strong metal-support interaction between Fe and mordenite was thus influenced by the varying ratios in the mordenite in a manner that paralleled the acidity and catalytic activity.

  13. Method for treating a nuclear process off-gas stream

    DOEpatents

    Pence, Dallas T.; Chou, Chun-Chao

    1984-01-01

    Disclosed is a method for selectively removing and recovering the noble gas and other gaseous components typically emitted during nuclear process operations. The method is adaptable and useful for treating dissolver off-gas effluents released during reprocessing of spent nuclear fuels whereby to permit radioactive contaminant recovery prior to releasing the remaining off-gases to the atmosphere. Briefly, the method sequentially comprises treating the off-gas stream to preliminarily remove NO.sub.x, hydrogen and carbon-containing organic compounds, and semivolatile fission product metal oxide components therefrom; adsorbing iodine components on silver-exchanged mordenite; removing water vapor carried by said stream by means of a molecular sieve; selectively removing the carbon dioxide components of said off-gas stream by means of a molecular sieve; selectively removing xenon in gas phase by passing said stream through a molecular sieve comprising silver-exchanged mordenite; selectively separating krypton from oxygen by means of a molecular sieve comprising silver-exchanged mordenite; selectively separating krypton from the bulk nitrogen stream using a molecular sieve comprising silver-exchanged mordenite cooled to about -140.degree. to -160.degree. C.; concentrating the desorbed krypton upon a molecular sieve comprising silver-exchange mordenite cooled to about -140.degree. to -160.degree. C.; and further cryogenically concentrating, and the recovering for storage, the desorbed krypton.

  14. Constructing a polyfunctional zeolite-encaged metal catalyst for the multistage oxidation of ethanol into ethyl acetate

    SciTech Connect

    Shakhtakhtinskii, T.N.; Aliev, A.M.; Kuliev, A.R.

    1995-08-01

    To construct an efficient polyfunctional catalyst for the given multistage reaction, the authors previously studied the catalysts HNaY, clinosorb, H-clinoptilolite, and H-mordenite in the reaction of esterification of ethanol with acetic acid; CuH-clinoptilolite, Cu-clinosorb, CuH-mordenite, and CuHNaY in the reaction of oxidative dehydration of ethanol; PdH-clinoptilolite, Pd-clinosorb, PdH-mordenite, and PdHNaY in the oxidation of ethanol; and CuPdH-clinoptilolite in the oxidative transformation of ethanol into ethyl acetate. The catalytic activity of these zeolites and other Pd- and Cu-containing zeolite catalysts, which the authors synthesized by the ion-exchange technique, was studied in a flow-circulating set-up.

  15. Distribution and chemistry of fracture-lining zeolites at Yucca Mountain, Nevada

    SciTech Connect

    Carlos, B.; Chipera, S.; Bish, D.; Raymond, R.

    1993-09-01

    Yucca Mountain, a > 1.5-km thick sequence of tuffs and subordinate lavas in southwest Nevada, is being investigated as a potential high-level nuclear waste repository site. Fracture-lining minerals are possible sources of information on past transport within the tuffs, and they may act as natural barriers to radionuclide migration along the fractures. Cores from several drill holes were examined to determine the distribution and chemistry of zeolite minerals in fractures. Fracture-lining minerals in the Paintbrush Tuff are highly variable in distribution, both vertically and laterally across the mountain, with mordenite, heulandite, and stellerite widespread in fractures even though the tuff matrix is generally devitrified and not zeolitic. Where heulandite occurs as both tabular and prismatic crystals in the same fracture, the two morphologies have different compositions, suggesting multiple episodes of zeolite formation within the fractures. In contrast to the Paintbrush Tuff, fractures in the Calico Hills Formation and the Crater Flat Tuff generally contain abundant clinoptilolite and mordenite only where the matrix is zeolitic, although mordenite does occur as fracture linings in some devitrified intervals of the Crater Flat Tuff as well. The fracture-lining zeolites correlate with the degree of alteration of the zeolitic tuffs, with clinoptilolite plus mordenite in tuffs containing clinoptilolite, and analcime in fractures limited to tuff intervals containing analcime. These data suggest that fracture-lining zeolite formation may have been coincident with the original alteration of the tuffs.

  16. Milestone Report - M4FT-14OR0312022 - Co-absorption studies - Design system complete/test plan complete

    SciTech Connect

    Bruffey, Stephanie H.; Spencer, Barry B.; Jubin, Robert Thomas

    2013-12-01

    The objective of this test plan is to describe research that will determine the effectiveness of silver mordenite and molecular sieve beds to remove iodine and water (tritium) from off-gas streams arising from used nuclear fuel recycling processes, and to demonstrate that the iodine and water can be recovered separately from one another.

  17. Synthesis of single-site copper catalysts for methane partial oxidation.

    PubMed

    Grundner, S; Luo, W; Sanchez-Sanchez, M; Lercher, J A

    2016-02-11

    Cu-Exchanged zeolites are known as active materials for methane oxidation to methanol. However, understanding of the formation of Cu active species during synthesis, dehydration and activation is fragmented and rudimentary. We show here how a synthesis protocol guided by insight in the ion exchange elementary steps leads to highly uniform Cu species in mordenite (MOR). PMID:26744744

  18. Hydrocarbon cracking catalyst and process utilizing the same

    SciTech Connect

    Gladrow, E.M.; Winter, W.E.

    1980-12-30

    A hydrocarbon cracking catalyst comprises an ultrastable y-type crystalline zeolite, a small pore crystalline zeolite such as mordenite, an inorganic oxide matrix and, optionally, a porous inert component. The cracking catalyst has a high activity and selectivity for the production of high octane naphtha fractions from higher boiling point hydrocarbonaceous oils. Catalytic cracking processes utilizing the catalyst are also provided.

  19. Cracking process with catalyst of combined zeolites

    SciTech Connect

    Gladrow, E. M.; Winter, W. E.

    1981-09-01

    A hydrocarbon cracking catalyst comprises an ultrastable y-type crystalline zeolite, a small pore crystalline zeolite such as mordenite, an inorganic oxide matrix and, optionally, a porous inert component. The cracking catalyst has a high activity and selectivity for the production of high octane naphtha fractions from higher boiling point hydrocarbonaceous oils. Catalytic cracking processes utilizing the catalyst are also provided.

  20. Infrared spectroscopy study of the sorption of selenium(IV) on natural zeolites

    NASA Astrophysics Data System (ADS)

    Zonkhoeva, E. L.; Sanzhanova, S. S.

    2011-07-01

    The sorption of selenium(IV) ions on single crystals of natural shabazite, analcime, mesolite, stilbite, and on clinoptilolite- and mordenite-containing tuffs in dependence on the concentration and pH of a solution of sodium selenite was studied by infrared spectroscopy. It was assumed that sorption on clinoptilolite and mordenite tuffs from a 0.1 M solution of sodium selenite with pH 9 occurs in the form of selenite and pyroselenite anions forming a hydrogen bond with the zeolite water molecules. It was established that water molecules in analcime, unlike stilbite, shabazite and mesolite, also form hydrogen bonds with the selenite ion in an alkaline medium. No hydrogen bonds are formed in diluted solutions or an acid medium. The partial desilylation and dealumination of zeolites in alkaline and acid media respectively, were observed.

  1. AuPt Alloy on TiO2: A Selective and Durable Catalyst for L-Sorbose Oxidation to 2-Keto-Gulonic Acid.

    PubMed

    Chan-Thaw, Carine E; Chinchilla, Lidia E; Campisi, Sebastian; Botton, Gianluigi A; Prati, Laura; Dimitratos, Nikolaos; Villa, Alberto

    2015-12-21

    Pt nanoparticles were prepared by a sol immobilization route, deposited on supports with different acid/base properties (MgO, activated carbon, TiO2 , Al2O3, H-Mordenite), and tested in the selective oxidation of sorbose to 2-keto-gulonic acid (2-KGUA), an important precursor for vitamin C. In general, as the basicity of the support increased, a higher catalytic activity occurred. However, in most cases, a strong deactivation was observed. The best selectivity to 2-KGUA was observed with acidic supports (TiO2 and H-Mordenite) that were able to minimize the formation of C1/C2 products. We also demonstrated that, by alloying Pt to Au, it is possible to enhance significantly the selectivity of Pt-based catalysts. Moreover, the AuPt catalyst, unlike monometallic Pt, showed good stability in recycling because of the prevention of metal leaching during the reaction. PMID:26611807

  2. Thermal stability of zeolitic tuff from Yucca Mountain, Nevada

    SciTech Connect

    Bish, D.L.

    1990-04-01

    Thermal models of the proposed repository at Yucca Mountain, Nevada, suggest that rocks near the proposed host rock will experience elevated temperatures for at least 1000 yrs. In order to assess the effects of elevated temperatures on zeolites clinoptilolite and mordenite were investigated using a combination of high-temperature X-ray powder diffraction, thermogravimetric and differential scanning calorimetric analysis, and long-term heating experiments. 13 refs., 7 figs.

  3. Oxygen and hydrogen isotope geochemistry of zeolites

    NASA Technical Reports Server (NTRS)

    Karlsson, Haraldur R.; Clayton, Robert N.

    1990-01-01

    Oxygen and hydrogen isotope ratios for natural samples of the zeolites analcime, chabazite, clinoptilolite, laumontite, mordenite, and natrolite have been obtained. The zeolite samples were classified into sedimentary, hydrothermal, and igneous groups. The ratios for each species of zeolite are reported. The results are used to discuss the origin of channel water, the role of zeolites in water-rock interaction, and the possibility that a calibrated zeolite could be used as a low-temperature geothermometer.

  4. Dehydration of cyclohexanol as a test reaction for zeolite acidity

    SciTech Connect

    Karge, H.G.; Kosters, H.; Wada, Y.

    1984-01-01

    Dehydration of cyclohexanol was investigated using a fixed-bed continuous flow reactor with acidic mordenite-type, clinoptilolite-type, and faujasite-type (Y) zeolites as catalysts. The surface acidity of the catalysts employed was studied by IR using pyridine or 2,6-di-tert. butylpyridine as probe molecules. A correlation between the acidity and the rates of dehydration was clearly shown.

  5. Direct observation of DME carbonylation in the different channels of H-MOR zeolite by continuous-flow solid-state NMR spectroscopy.

    PubMed

    He, Ting; Ren, Pengju; Liu, Xianchun; Xu, Shutao; Han, Xiuwen; Bao, Xinhe

    2015-12-01

    The dynamic evolution of acetyl intermediates in the two different channels of H-mordenite (H-MOR) zeolite during dimethyl ether (DME) carbonylation is tracked by using in situ solid-state NMR spectroscopy under continuous-flow conditions. Thus, the reaction path via methyl acetate produced over active sites in 8 member ring (MR) channels, followed by diffusion into 12 MR channels, is proposed. PMID:26451500

  6. Selective oxidation of glycerol under acidic conditions using gold catalysts

    SciTech Connect

    Villa, Alberto; Veith, Gabriel M; Prati, Laura

    2010-01-01

    H-mordenite-supported PtAu nanoparticles are highly active and selective in the oxidation of glycerol under acidic conditions, which allows the direct preparation of free acids (see picture). The high selectivity for C{sub 3} compounds results from the negligible formation of H{sub 2}O{sub 2}, in contrast to PtAu nanoparticles supported on activated carbon.

  7. An electron paramagnetic resonance spectroscopy investigation of the retention mechanisms of Mn and Cu in the nanopore channels of three zeolite minerals

    SciTech Connect

    Ferreira, Daniel R.; Schulthess, Cristian P.; Amonette, James E.; Walter, Eric D.

    2012-12-01

    The adsorption mechanisms of divalent cations in zeolite nanopore channels can vary as a function of their pore dimensions. The nanopore inner-sphere enhancement (NISE) theory predicts that ions may dehydrate inside small nanopore channels in order to adsorb more closely to the mineral surface if the nanopore channel is sufficiently small. The results of an electron paramagnetic resonance (EPR) spectroscopy study of Mn and Cu adsorption on the zeolite minerals zeolite Y (large nanopores), ZSM-5 (intermediate nanopores), and mordenite (small nanopores) are presented. The Cu and Mn cations both adsorbed via an outer-sphere mechanism on zeolite Y based on the similarity between the adsorbed spectra and the aqueous spectra. Conversely, Mn and Cu adsorbed via an inner-sphere mechanism on mordenite based on spectrum asymmetry and peak broadening of the adsorbed spectra. However, Mn adsorbed via an outer-sphere mechanism on ZSM-5, whereas Cu adsorbed on ZSM-5 shows a high degree of surface interaction that indicates that it is adsorbed closer to the mineral surface. Evidence of dehydration and immobility was more readily evident in the spectrum of mordenite than ZSM-5, indicating that Cu was not as close to the surface on ZSM-5 as it was when adsorbed on mordenite. Divalent Mn cations are strongly hydrated and are held strongly only in zeolites with small nanopore channels. Divalent Cu cations are also strongly hydrated, but can dehydrate more easily, presumably due to the Jahn-Teller effect, and are held strongly in zeolites with medium sized nanopore channels or smaller.

  8. Summary of FY 2010 Iodine Capture Studies at the INL

    SciTech Connect

    Daryl R. Haefner; Tony L. Watson; Michael G. Jones

    2010-08-01

    Three breakthrough runs using silver mordenite sorbents were conducted and a dynamic sorption capacity estimated based on MeI analysis from a 2" bed. However, it is now believed the data for the first 2 runs is incomplete because the contributions from elemental iodine were not included. Although the only source of iodine was MeI, elemental iodine was generated within the sorbent bed, presumably from a recombination reaction likely catalyzed by silver mordenite. On-line effluent analysis with a GC was only capable of analyzing MeI, not I2. Scrub samples drawn during Run #3, which are specific for I2, show significant levels of I2 being emitted from a partially spent Ag-mordenite bed. By combining MeI and I2 analyses, a well defined total iodine breakthrough curve can be generated for Run #3. At the conclusion of Run #3 (IONEX Ag-900 was the sorbent) the effluent level from Bed 2 was approaching 70% of the feed concentration. The leading bed (Bed 1) had an estimated average loading of 66 mg I/g sorbent, Bed 2's was 52 mg I/g. The corresponding silver utilizations (assuming formation of AgI) were about 59% and 46%, respectively. The spent sorbents are being sent to Sandia National Laboratories for confirmatory analysis of iodine and silver utilization as well as source material for waste form development.

  9. Heterogeneous catalysts for the direct, Halide-free carbonylation of methanol

    SciTech Connect

    Ellis, B.; Smith, W.J.; Howard, M.J.

    1996-12-31

    Copper containing mordenite catalysts (Cu-MOR) have been shown to be active and selective for the carbonylation of methanol under moderate conditions in the vapour phase and in the absence of any halide promoter. This paper describes the preparation, performance and in particular the characterization of this class of catalyst, comparing its performance with H-mordenite, which is also shown to be active in the carbonylation reaction. Initially both Cu-MOR and H-MOR catalyst methanol to gasoline (MTG) chemistry, but after about 6 hours on stream under typical conditions, (T = 623 K, p = 10 bar, CO: methanol ratio ca 10:1) acetic acid becomes the main product over Cu-MOR. Selectivity to acetyls (acetic acid + methyl acetate) remains at > 70% for ca 12 hours but gradually declines, giving way to the formation of dimethyl ether. H-MOR shows similar trends, but the period when MTG chemistry is observed is longer and that where acetyls are formed is shorter. Initially Cu(II) ions are distributed throughout the mordenite pore structure, but by the time activity to acetyls is observed the pore structure has largely become blocked by polymethyl benzenes, and much of the copper has become aggregated into large metal particles (d > 120 {Angstrom}). However FTIR studies using carbon monoxide as a probe molecule show that some non-zerovalent copper ions are still accessible. Structure - function relationships for these interesting materials are discussed briefly.

  10. Distribution of potentially hazardous phases in the subsurface at Yucca Mountain, Nevada

    SciTech Connect

    Guthrie, G.D. Jr.; Bish, D.L.; Chipera, S.J.; Raymond, R. Jr.

    1995-05-01

    Drilling, trenching, excavation of the Exploratory Studies Facility, and other surface and underground-distributing activities have the potential to release minerals into the environment from tuffs at Yucca Mountain, Nevada. Some of these minerals may be potential respiratory health hazards. Therefore, an understanding of the distribution of the minerals that may potentially be liberated during site-characterization and operation of the potential repository is crucial to ensuring worker and public safety. Analysis of previously reported mineralogy of Yucca Mountain tuffs using data and criteria from the International Agency for Research on Cancer (IARC) suggests that the following minerals are of potential concern: quartz, cristobalite, tridymite, opal-CT, erionite, mordenite, and palygorskite. The authors have re-evaluated the three-dimensional mineral distribution at Yucca Mountain above the static water level both in bulk-rock samples and in fractures, using quantitative X-ray powder diffraction analysis. Erionite, mordenite, and palygorskite occur primarily in fractures; the crystalline-silica minerals, quartz, cristobalite, and tridymite are major bulk-rock phases. Erionite occurs in the altered zone just above the lower Topopah Spring Member vitrophyre, and an occurrence below the vitrophyre but above the Calico Hills has recently been identified. In this latter occurrence, erionite is present in the matrix at levels up to 35 wt%. Mordenite and palygorskite occur throughout the vadose zone nearly to the surface. Opal-CT is limited to zeolitic horizons.

  11. Catalytic degradation of high-density polyethylene over different zeolitic structures

    SciTech Connect

    Manos, G.; Garforth, A.; Dwyer, J.

    2000-05-01

    The catalytic degradation of high-density polyethylene to hydrocarbons was studied over different zeolites. The product range was typically between C{sub 3} and C{sub 15} hydrocarbons. Distinctive patterns of product distribution were found with different zeolitic structures. Over large-pore ultrastable Y, Y, and {beta} zeolites, alkanes were the main products with less alkenes and aromatics and only very small amounts of cycloalkanes and cycloalkenes. Medium-pore mordenite and ZSM-5 gave significantly more olefins. In the medium-pore zeolites secondary bimolecular reactions were sterically hindered, resulting in higher amounts of alkenes as primary products. The hydrocarbons formed with medium-pore zeolites were lighter than those formed with large-pore zeolites. The following order was found regarding the carbon number distribution: (lighter products) ZSM-5 < mordenite < {beta} < Y < US-Y (heavier products). A similar order was found regarding the bond saturation: (more alkenes) ZSM-5 < mordenite < {beta} < Y < US-Y (more alkanes). Dependent upon the chosen zeolite, a variety of products was obtained with high values as fuel, confirming catalytic degradation of polymers as a promising method of waste plastic recycling.

  12. Deactivation behaviors of zeolite and silica-alumina catalysts in the degradation of polyethylene

    SciTech Connect

    Uemichi, Yoshio; Hattori, Masahiko; Itoh, Toshihiro; Nakamura, Junko; Sugioka, Masatoshi

    1998-03-01

    For chemical recycling of waste plastics, HZSM-5, HY, and H-mordenite zeolites and silica-alumina were examined as catalysts for the degradation of polyethylene in a fixed-bed flow reactor system, and their activities and deactivation behaviors caused by coke deposition were studied. HZSM-5 catalyst was fond to be very effective for the production of gasoline-range fuel oils mainly consisting of isoparaffins and aromatics and showed no deactivation due to a very low yield of coke deposited on the catalyst surface, whereas in the degradation of polystyrene a marked deactivation was observed. Silica-alumina gradually deactivated as time on stream increased, but the degree of deactivation was less than expected from the deposition of a significant amount of coke, probably because the coke deposition in the large pores of the catalyst caused no marked influence on the diffusion of the decomposed fragments involved in the reaction. On the other hand, deactivations of HY and H-mordenite were striking; the latter was most abruptly deactivated, resulting in a marked decrease in the liquid yield. From the surface area measurements of the used catalysts, it was suggested that the pores of HY were sufficiently filled out with coke, while pore blocking by coke occurred in the unidimensional channels of H-mordenite.

  13. New catalysts for the indirect liquefaction of coal. Second annual technical report, August 1, 1981-July 31, 1982

    SciTech Connect

    Melson, G.A.

    1982-01-01

    Series of zeolite-supported iron-containing catalysts with weight percent iron (% Fe) varying from approx. 1 to approx. 17% Fe have been prepared from Fe/sub 3/(CO)/sub 12/ and the synthetic zeolites ZSM-5, mordenite and 13X by an extraction technique. The zeolites ZSM-5 and mordenite were used in the acid form, 13X in the sodium form. The catalysts were characterized by a variety of techniques including infrared spectroscopy, X-ray powder diffractometry, X-ray photoelectron spectroscopy, ion-scattering spectrometry and Mossbauer spectroscopy. All catalysts contain highly dispersed, small particle-sized ..gamma..-Fe/sub 2/O/sub 3/ with a small amount of the iron (0.6 to 1.5% Fe depending on the support) located in the pores of the support. Evaluation of the catalytic ability of some of these materials for synthesis gas conversion was conducted at 280/sup 0/C and 300/sup 0/C by using a fixed-bed continuous flow microreactor. All catalysts evaluated produce significant quantities of hydrocarbons. The distribution of hydrocarbons varies, depending upon the support used, for catalysts with similar weight percent iron. For the liquid hydrocarbons, Fe/ZSM-5 produces the highest percentage of aromatics, Fe/mordenite produces the highest percentage of olefins, and Fe/13X produces the highest percentage of saturates. The effect of support acidity and pore structure on hydrocarbon product distribution is discussed.

  14. Interactions of backfill materials with cesium in a bittern brine under repository conditions

    SciTech Connect

    Komarneni, S.; Roy, R.

    1982-03-01

    The following potential backfill materials have been studied: phillipsite, clinoptilolite, mordenite, montmorillonites, vermiculites, chlorite, kaolinite, labradorite, and shales. Each of these was hydrothermally reacted with Cs/sub 2/MoO/sub 4/, a possible cesium phase in spent fuel elements, in the presence of a bittern brine at 200/sup 0/C for two months under a confining pressure of 300 bars. Analyses of the product solutions indicated that montmorillonites, vermiculites, and zeolites fixed (as determined by resistance to K+ washing) the greatest fractions of the added cesium while other minerals, labradorite, and shales fixed only about 10% of the added cesium. For example, montmorillonite from Arizona and phillipsite from California fixed 47 and 50%, respectively, of the cesium added. X-ray diffraction analysis of the solid products revealed that cesium was fixed in the interlayers of montmorillonite as indicated by the collapse of the c-spacing from 15.5 to 12.1 A. Cesium interaction with clinoptilolite and mordenite zeolites did not result in their alteration or in any new cesium minerals as observed by x-ray diffraction. The cesium aluminosilicate mineral, pollucite, was detected only with phillipsite-cesium interactions in brine unlike in the hydrothermal interaction of these materials with Cs/sub 2/MoO/sub 4/ in deionized water where the presence of pollucite was found earlier to be pervasive. Powellite, CaMoO/sub 4/, was the only new phase found in all these interactions by x-ray diffraction which resulted from the combination of calcium from brine with molybdenum from Cs/sub 2/MoO/sub 4/. Montmorillonites among clay minerals and zeolites such as clinoptilolite and mordenite seem to be the best backfill materials in salt.

  15. Electron transfers in a TiO2-containing MOR zeolite: synthesis of the nanoassemblies and application using a probe chromophore molecule.

    PubMed

    Legrand, A; Moissette, A; Hureau, M; Casale, S; Massiani, P; Vezin, H; Mamede, A S; Batonneau-Gener, I

    2014-07-14

    New assemblies constituted by a microporous matrix of mordenite (MOR) zeolite on which TiO2 nanoclusters are deposited were synthesized using ionic oxalate complexes and TiCl3 titanium precursors. The samples were used to investigate the transfer of electrons produced by spontaneous or photo-induced ionization of a guest molecule (t-stilbene, t-St) occluded in the porous volume towards the conduction band of a conductive material placed nearby, in the pores or at least close to their entrance. The reaction mechanisms were compared in these Ti-rich solids and in a Ti-free mordenite sample. The characterization by XRD, N2 physisorption, TEM, XPS and DRIFT spectroscopy of the supramolecular TiO2/MOR systems before t-St adsorption showed the preservation of the crystalline structure after Ti addition and thermal activation treatments. They also revealed that titanium is mainly located at the external surface of the zeolite grains, in the form of highly dispersed and/or aggregated anatase. After incorporation of the guest molecule in the new assemblies, diffuse reflectance UV-visible and EPR spectroscopies indicate that the electron transfer processes are similar with and without TiO2 but strongly stabilized t-St˙(+) radicals are detected in the TiO2-MOR samples whereas such species were never detected earlier in TiO2-free mordenite using these techniques. The stabilization process is found to be more efficient in the sample prepared with TiCl3 as the precursor than with titanium oxalates. It is proposed that the proximity of TiO2 with the formed t-St˙(+) radicals provokes the stabilization of the radical through capture of the ejected electron by the semi-conductor and that confinement effects can also play a role. PMID:24866869

  16. Aluminum-phosphate binder formation in zeolites as probed with X-ray absorption microscopy.

    PubMed

    van der Bij, Hendrik E; Cicmil, Dimitrije; Wang, Jian; Meirer, Florian; de Groot, Frank M F; Weckhuysen, Bert M

    2014-12-24

    In this work, three industrially relevant zeolites with framework topologies of MOR, FAU and FER have been explored on their ability to form an AlPO4 phase by reaction of a phosphate precursor with expelled framework aluminum. A detailed study was performed on zeolite H-mordenite, using in situ STXM and soft X-ray absorption tomography, complemented with (27)Al and (31)P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, XRD, FT-IR spectroscopy, and N2 physisorption. Extraframework aluminum was extracted from steam-dealuminated H-mordenite and shown to dominantly consist of amorphous AlO(OH). It was found that phosphoric acid readily reacts with the AlO(OH) phase in dealuminated H-mordenite and forms an extraframework amorphous AlPO4 phase. It was found that while AlPO4 crystallizes outside of the zeolitic channel system forming AlPO4 islands, AlPO4 that remains inside tends to stay more amorphous. In the case of ultrastable zeolite Y the FAU framework collapsed during phosphatation, due to extraction of framework aluminum from the lattice. However, using milder phosphatation conditions an extraframework AlPO4 α-cristobalite/tridymite phase could also be produced within the FAU framework. Finally, in steamed zeolite ferrierite with FER topology the extraframework aluminum species were trapped and therefore not accessible for phosphoric acid; hence, no AlPO4 phase could be formed within the structure. Therefore, the parameters to be taken into account in AlPO4 synthesis are the framework Si/Al ratio, stability of framework aluminum, pore dimensionality and accessibility of extraframework aluminum species. PMID:25415849

  17. Removal of radionuclides using zeolites

    SciTech Connect

    Reddy, R.G.; Cai, Z.

    1996-10-01

    Adsorption of uranium(VI) from aqueous solutions on natural zeolites, i.e., chabazite, clinoptilolite, erionite and mordenite, was investigated. The influence of time and pH of the solution were studied. The results showed that uranium(VI) species are strongly adsorbed on the zeolites between pH 6 to 9. The amount of uranium adsorption is strongly dependent on pH and, to some extent, on the type of zeolites. For pH {ge} 6 and at 25 C, more than 92% of uranium from solution was removed in 10 minutes. Adsorption mechanism of uranium is discussed.

  18. SNL Sigma Off-Gas Team Contribution to the FY15 DOE/NE-MRWFD Campaign Accomplishments Report.

    SciTech Connect

    Nenoff, Tina M.

    2015-08-21

    This program at Sandia is focused on Iodine waste form development for Fuel Cycle R&D needs. Our research has a general theme of “Capture and Storage of Iodine Fission Gas “ in which we are focused on silver loaded zeolite waste forms, evaluation of iodine loaded getter materials (eg., mordenite zeolite), and the development of low temperature glass waste forms that successfully incorporate iodine loaded getter materials from I2, organic iodide, etc. containing off-gas streams.

  19. Zeolite crystal growth in space - What has been learned

    NASA Technical Reports Server (NTRS)

    Sacco, A., Jr.; Thompson, R. W.; Dixon, A. G.

    1993-01-01

    Three zeolite crystal growth experiments developed at WPI have been performed in space in last twelve months. One experiment, GAS-1, illustrated that to grow large, crystallographically uniform crystals in space, the precursor solutions should be mixed in microgravity. Another experiment evaluated the optimum mixing protocol for solutions that chemically interact ('gel') on contact. These results were utilized in setting the protocol for mixing nineteen zeolite solutions that were then processed and yielded zeolites A, X and mordenite. All solutions in which the nucleation event was influenced produced larger, more 'uniform' crystals than did identical solutions processed on earth.

  20. Zeolite catalysis: technology

    SciTech Connect

    Heinemann, H.

    1980-07-01

    Zeolites have been used as catalysts in industry since the early nineteen sixties. The great majority of commercial applications employ one of three zeolite types: zeolite Y; Mordenite; ZSM-5. By far the largest use of zeolites is in catalytic cracking, and to a lesser extent in hydrocracking. This paper reviews the rapid development of zeolite catalysis and its application in industries such as: the production of gasoline by catalytic cracking of petroleum; isomerization of C/sub 5/ and C/sub 6/ paraffin hydrocarbons; alkylation of aromatics with olefins; xylene isomerization; and conversion of methanol to gasoline.

  1. Pulsed laser deposition of zeolitic membranes

    SciTech Connect

    Peachey, N.M.; Dye, R.C.; Ries, P.D.

    1995-02-01

    The pulsed laser deposition of zeolites to form zeolitic thin films is described. Films were grown using both mordenite and faujasite targets and were deposited on various substrates. The optimal films were obtained when the target and substrate were separated by 5 cm. These films are comprised of small crystallites embedded in an amorphous matrix. Transmission electron microscopy reveals that the amorphous material is largely porous and that the pores appear to be close to the same size as the parent zeolite. Zeolotic thin films are of interest for sensor, gas separation, and catalytic applications.

  2. Catalytic degradation of high density polyethylene using zeolites.

    PubMed

    Zaggout, F R; al Mughari, A R; Garforth, A

    2001-01-01

    Plastic wastes, which cause a serious environmental problem in urban areas, can serve as sources of energy. Catalytic treatment of High Density Polyethylene (HDPE) has shown that the degradation of HDPE resulted in the production of a stream of gaseous hydrocarbons varied in the range C1-C8. The degradation was carried out using diluted forms of zeolites ZSM-5, USY and Mordenite (MORD) using a fluidized bed reactor (FBR). Effect of coke formation on the activity of the catalysts was screened by thermogravimetric (TGA). ZSM-5 showed a significant resistance to deactivation because of the nature of its small pore size compared with USY and MORD. PMID:11382018

  3. Equilibrium modeling of the formation of zeolites in fractures at Yucca Mountain, Nevada

    SciTech Connect

    Chipera, S.J.; Bish, D.L.; Carlos, B.A.

    1993-08-01

    Yucca Mountain, in southern Nevada, is currently being investigated to determine its suitability to host the first US high-level nuclear waste repository. One of the reasons that Yucca Mountain was chosen for study is the presence of thick sequences of zeolite-rich horizons. In as much as fractures may serve as potential pathways for aqueous transport, the minerals that line fractures are of particular interest. Zeolites are common in fractures at Yucca Mountain and consist mainly of clinoptilolite/heulandite and mordenite although sporadic occurrences of chabazite, erionite, phillipsite, and stellrite have been identified using X-ray powder diffraction. To understand better the conditions under which the observed zeolite species were formed, thermodynamic data were estimated and calculations of log a((K{sup +}){sup 2}/Ca{sup ++}) versus log a((Na{sup +}){sup 2}/Ca{sup ++}) were conducted at various temperatures and silica activities. Using present-day Yucca Mountain water chemistries as a lower constraint on silica activity, clinoptilolite/heulandite and mordenite are still the zeolite species that would form under present conditions.

  4. Diagenesis of basalts from the Pasco Basin, Washington. I. Distribution and composition of secondary mineral phases

    SciTech Connect

    Benson, L.V.; Teague, L.S.

    1982-01-01

    The principal components of secondary mineral assemblages found in Pasco Basin basalts are iron-rich smectite (nontronite), clinoptilolite, and silica. Silica occurs as quartz, cristobalite, tridymite, and opal-CT. Extractable iron within the nontronite suggests the presence of an iron-bearing oxyhydroxide phase intercalated with the nontronite. Other components present in minor or trace amounts are mordenite, celadonite, apatite, pyrite, phillipsite, gypsum, crionite, and chabazite. The generalized precipitation sequence with time and/or depth was found to be clay (usually nontronite) ..-->.. clinoptilolite ..-->.. silica and/or clay. Nontronite, the first phase to form, is present at nearly all sampled depths. Clinoptilolite is apparently restricted to depths below about 350 m. Quartz is ubiquitous whereas opal and cristobalite appear to be abundant only below 600 m. Mordenite occurs only at depths below about 900 m, which correlates roughly with the first occurrence of dissolution-etched clinoptilolite. These observations as well as comparisons with data on secondary minearl assemblages from other basaltic and felsic systems suggest that the geochemical evolution of Pasco Basin basalts probably occurred under conditions similar to those existing today.

  5. Removal of metal cations from water using zeolites

    SciTech Connect

    Zamzow, M.J.; Murphy, J.E. )

    1992-11-01

    Zeolites from abundant natural deposits were investigated by the Bureau of Mines for efficiently cleaning up mining industry wastewaters. Twenty-four zeolite samples were analyzed by x-ray diffraction and inductively coupled plasma. These included clinoptilolite, mordenite, chabazite, erionite, and phillipsite. Bulk densities of a sized fraction ([minus]40, +65 mesh) varied from 0.48 to 0.93 g/ml. Attrition losses ranged from 1 to 18% during an hour-long shake test. The 24 zeolites and an ion-exchange resin were tested for the uptake of Cd, Cu, and Zn. Of the natural zeolites, phillipsite proved to be the most efficient, while the mordenites had the lowest uptakes. Sodium was the most effective exchangeable ion for exchange of heavy metals. Wastewater from an abandoned copper mine in Nevada was used to test the effectiveness of clinoptilolite for treating a multi-ion wastewater. The metal ions Fe[sup 3+], Cu[sup 2+], and Zn[sup 2+] in the copper mine wastewater were removed to below drinking water standards, but Mn[sup 2+] and Ni[sup 2+] were not. Calcium and NH[sub 4][sup +] interfered with the uptake of heavy metals. Adsorbed heavy metals were eluted from zeolites with a 3% NaCl solution. Heavy metals were concentrated in the eluates up to 30-fold relative to the waste solution. Anions were not adsorbed by the zeolites.

  6. Advanced fire-resistant forms of activated carbon and methods of adsorbing and separating gases using same

    SciTech Connect

    Xiong, Yongliang; Wang, Yifeng

    2015-02-03

    Advanced, fire-resistant activated carbon compositions useful in adsorbing gases; and having vastly improved fire resistance are provided, and methods for synthesizing the compositions are also provided. The advanced compositions have high gas adsorption capacities and rapid adsorption kinetics (comparable to commercially-available activated carbon), without having any intrinsic fire hazard. They also have superior performance to Mordenites in both adsorption capacities and kinetics. In addition, the advanced compositions do not pose the fibrous inhalation hazard that exists with use of Mordenites. The fire-resistant compositions combine activated carbon mixed with one or more hydrated and/or carbonate-containing minerals that release H.sub.2O and/or CO.sub.2 when heated. This effect raises the spontaneous ignition temperature to over 500.degree. C. in most examples, and over 800.degree. C. in some examples. Also provided are methods for removing and/or separating target gases, such as Krypton or Argon, from a gas stream by using such advanced activated carbons.

  7. Encapsulation of lead sulfide molecular clusters into solid matrices. Structural analysis with x-ray absorption spectroscopy

    SciTech Connect

    Moller, K.; Bein, T. ); Herron, N.; Mahler, W.; Wang, Ying )

    1989-07-26

    Molecular-size PbS species have been stabilized in the open-pore structure of zeolite Y and mordenite via ion exchange with Pb(II) and subsequent treatment with H{sub 2}S at 295 K. Detailed analysis of synchrotron x-ray absorption data of the Pb L{sub III}-edge shows that intrazeolite PbO{sub 2}(O{sub z} = zeolite oxygen) species in zeolite Y react with H{sub 2}S to form monomolecular S{sub 2}Pb(I{sub z}){sub 3} species that are still anchored to the zeolite framework. The intrazeolite PbS phase appears to be more ordered at high loading levels of lead in zeolite Y than at low loading levels. The coordination of Pb(II) and the structure of PbS in the mordenite host is less ordered but basically very similar to that of the monomolecular species in Y. Optical absorption data for these samples agree very well with the structural EXAFS results. Larger PbS clusters have been stabilized in 85% ethylene-15% methacrylic acid copolymer films by a similar preparation procedure. EXAFS data indicate that the reaction forms PbS clusters with several Pb coordination shells and that the conversion of PbS is a function of Pb(II) loading levels. 23 refs., 9 figs., 3 tabs.

  8. Aluminum coordination and active sites on aluminas, Y zeolites and pillared silicates. Progress report, January 31, 1992--January 31, 1993

    SciTech Connect

    Fripiat, J.J.

    1992-12-31

    Effort was continued to characterize the nature of the Al species responsible for Lewis acidity in zeolites and in aluminas by NMR. While numerous techniques have been successful for scaling the acid strength of Broensted sites, the situation is not satisfactory for the Lewis acid sites. Initial rate of dehydrochlorination of 1,1,1-trichloroethane is sensitive to strength of Lewis acid sites. N-Butene isomerization has been extended to the new aluminas obtained from nano-sized precursors. O-Xylene isomerization was carried out in a recirculation reactor on H-mordenite samples containing Lewis or Broensted acid sites; effects of H{sub 2} and NO were also investigated. Cracking of methylcyclohexane and 3-methylpentane was investigated by EPR on H-mordenite. Sepiolite, a Mg silicate with zeolitic channels, had Al substituted for Si; the negative charge is balanced by, say, VO{sup 2+}. Transformation of ethanol into butadiene on this dual-function catalyst appears to result from a Prins reaction between acetaldeyde formed on the redox sites and ethylene resulting from dehydration of ethanol on Lewis sites.

  9. Paramagnetic complexes of 9,10-anthraquinone on zeolite surfaces and their thermal transformations

    NASA Astrophysics Data System (ADS)

    Fionov, A. V.; Nekhaev, A. I.; Shchapin, I. Yu.; Maksimov, A. L.; Lunin, V. V.

    2013-12-01

    The concentration of one-electron transfer sites on the surface of H-ZSM-5, H-Y, H-mordenite, and H-β zeolites was measured by EPR using 9,10-antrhraquinone as a probe. It has been found that the hyperfine structure from four protons typical for one-centered complexes of anthraquinone with one acidic site was observed in the EPR spectra after anthraquinone interaction with a zeolite surface in the temperature range of 373 to 423 K. It has been established that an elevated temperature of 473 K promoted the decomposition of the adsorbed anthraquinone and the disappearance of the hyperfine structure. It has been shown that the thermal instability of anthraquinone adsorbed on zeolites changed in the series H-β > H-Y > H-ZSM-5 ˜ H-mordenite; the coke-forming ability of zeolites with regard to n-decane at 443 K changed in a similar manner. It has been established that the presence of air promoted coke-forming processes upon interaction between n-decane and zeolites.

  10. Calibration analysis of zeolites by laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Horňáčková, M.; Grolmusová, Z.; Horňáček, M.; Rakovský, J.; Hudec, P.; Veis, P.

    2012-08-01

    Laser induced breakdown spectroscopy was used for calibration analysis of different types of microporous crystalline aluminosilicates with exactly ordered structure — zeolites. The LIBS plasma was generated using a Q-switched Nd:YAG laser operating at the wavelength of 532 nm and providing laser pulses of 4 ns duration. Plasma emission was analysed by echelle type emission spectrometer, providing wide spectral range 200-950 nm. The spectrometer was equipped with intensified CCD camera providing rapid spectral acquisition (gating time from 5 ns). The optimum experimental conditions (time delay, gate width and laser pulse energy) have been determined for reliable use of LIBS for quantitative analysis. Samples of different molar ratios of Si/Al were used to create the calibration curves. Calibration curves for different types of zeolites (mordenite, type Y and ZSM-5) were constructed. Molar ratios of Si/Al for samples used for calibration were determined by classical wet chemical analysis and were in the range 5.3-51.8 for mordenite, 2.3-12.8 for type Y and 14-600 for ZSM-5. Zeolites with these molar ratios of Si/Al are usually used as catalysts in alkylation reactions. Laser induced breakdown spectroscopy is a suitable method for analysis of molar ratio Si/Al in zeolites, because it is simple, fast, and does not require sample preparation compared with classical wet chemical analysis which are time consuming, require difficult sample preparation and manipulation with strong acids and bases.

  11. Radioactive iodine separations and waste forms development.

    SciTech Connect

    Krumhansl, James Lee; Nenoff, Tina Maria; Garino, Terry J.; Rademacher, David

    2010-04-01

    Reprocessing nuclear fuel releases gaseous radio-iodine containing compounds which must be captured and stored for prolonged periods. Ag-loaded mordenites are the leading candidate for scavenging both organic and inorganic radioiodine containing compounds directly from reprocessing off gases. Alternately, the principal off-gas contaminant, I2, and I-containing acids HI, HIO3, etc. may be scavenged using caustic soda solutions, which are then treated with bismuth to put the iodine into an insoluble form. Our program is focused on using state-of-the-art materials science technologies to develop materials with high loadings of iodine, plus high long-term mechanical and thermal stability. In particular, we present results from research into two materials areas: (1) zeolite-based separations and glass encapsulation, and (2) in-situ precipitation of Bi-I-O waste forms. Ag-loaded mordenite is either commercially available or can be prepared via a simple Ag+ ion exchange process. Research using an Ag+-loaded Mordenite zeolite (MOR, LZM-5 supplied by UOP Corp.) has revealed that I2 is scavenged in one of three forms, as micron-sized AgI particles, as molecular (AgI)x clusters in the zeolite pores and as elemental I2 vapor. It was found that only a portion of the sorbed iodine is retained after heating at 95o C for three months. Furthermore, we show that even when the Ag-MOR is saturated with I2 vapor only roughly half of the silver reacted to form stable AgI compounds. However, the Iodine can be further retained if the AgI-MOR is then encapsulated into a low temperature glass binder. Follow-on studies are now focused on the sorption and waste form development of Iodine from more complex streams including organo-iodine compounds (CH3I). Bismuth-Iodate layered phases have been prepared from caustic waste stream simulant solutions. They serve as a low cost alternative to ceramics waste forms. Novel compounds have been synthesized and solubility studies have been completed

  12. Radium-thorium disequilibrium and zeolite-water ion exchange in a Yellowstone hydrothermal environment

    NASA Astrophysics Data System (ADS)

    Sturchio, N. C.; Bohlke, J. K.; Binz, C. M.

    1989-05-01

    Whole rock samples of hydrothermally altered Biscuit Basin rhyolite from Yellowstone drill cores Y-7 and Y-8 were analyzed for 226Ra and 230Th to determine the extent of radioactive disequilibrium and its relation to the rates and mechanisms of element transport in the shallow portion of an active hydrothermal system. The ( 226Ra/230Th) activity ratios range from 0.73 to 1.46 and are generally correlated with Th-normalized Ba concentrations (Ba N). Values of ( 226Ra/230Th) and Ba N > 1 were found in samples containing large modal fractions of clinoptilolite; whereas values of ( 226Ra/230Th) and Ba N < 1 were found in samples containing large modal fractions of mordenite. Composition clinoptilolite and mordenite in these samples are consistent with ion exchange equilibrium between zeolites and coexisting thermal waters. Average K d mineral-waterBa values are 1.0·10 5 mL/g for clinoptilolite and 1.4·10 4 mL/g for mordenite. Apparent diffustvities through matrix porosity estimated for Ra and Ba range from ˜10 -12 to ˜10 -10 cm 2s -1 in thoroughly zeolitic rhyolite; these rates of diffusion are too low to account for the observed distance scale of ( 226Ra/230Th) disequilibrium. The correlated values of ( 226Ra /230Th) disequilibrium and Ba N represent zeolite-water ion exchange equilibrium that is caused by porous flow of water through the rock matrix and by the relatively rapid diffusion of cations within the zeolite lattices. A water flux of at least ˜2.5 ( cm water3/cm rock3) yr -1 is required to produce measurable ( 226Ra/230Th) disequilibrium, whereas at least ˜23 ( cm water3/cm rock3) yr -1 is r for the sample exhibiting the most extreme ( 226Ra/230Th) disequilibrium; these fluxes are much higher than those that can be inferred from net mass transfers of stable species. The zeolite-water ion exchange process appears to have been operating for at least 8000 yr in the environment of the Y-7 and Y-8 drill holes.

  13. Milestone Report - M4FT-15OR0312026 - Complete NO and NO2 aging of AgZ

    SciTech Connect

    Bruffey, Stephanie H.; Patton, Kaara K.; Walker, Jr, Joseph Franklin; Jubin, Robert Thomas

    2015-03-31

    In an off-gas system within a nuclear fuel reprocessing plant, any capture material will be exposed to a gas stream for months at a time. This gas stream may be at elevated temperature and could contain water, NOx gas, or a variety of other constituents that comprise the off-gas stream. For this reason, it is important to understand the effects of long-term exposure, or aging, on proposed capture materials. One material under consideration is silver-exchanged mordenite (AgZ). The aim of this study was to determine the effect of extended exposure at 150°C to an air stream containing NO on the iodine capture capacity of the hydrogen reduced form of AgZ designated as Ag0Z. The study was originally also intended to expand on the static NO2 aging studies by exposing Ag0Z to a flowing stream of NO2 for an extended period of time, but those tests were delayed due to NO2 production schedules by the gas vendor. Unreduced silver mordenite has a loading capacity of approximately 25 mg I/g AgZ and that capacity is increased to 100 mg I/g Ag0Z upon reduction. It appears that extended exposure of AgZ to 1% NO at 150°C may not only neutralize the increased capacity gained by reduction, but perhaps degrade the sorbent even further. Loss of 80% of sorbent capacity and surface area was observed after 8 weeks of exposure to a 1% NO stream at 150°C. Investigations continue into the effects of aging by off-gas components on iodine sorbents. Future work will age silver mordenite with streams containing NO2. As the simulated off-gas streams become more complex and more corrosive, the ability of AgZ to withstand conditions present in off-gas streams will be more fully known.

  14. Upgrading of coal-derived liquids. 1. Catalytic activities of zeolite catalysts and commercial HDS catalysts

    SciTech Connect

    Yoshida, R.; Hara, S.; Yoshida, T.; Yokoyama, S.; Nakata, Y.; Goto, Y.; Maekawa, Y.

    1983-01-01

    The applicability of various zeolite catalysts and commercial hydrodesulfurization (HDS) catalysts to the secondary hydrotreatment of coal-derived liquids was examined in relation to the chemical structure of upgraded liquids. The catalytic activities of zeolite catalysts for HI conversion is lower than are the activities of Ni-Mo, Ni-Co-Mo, Co-Mo and Ni-W catalysts. However, as regards hydrogenation and the removal of nitrogen, zeolite catalysts such as natural clinoptilolite and mordenite have almost the same activity as do Co-Mo and Ni-W catalysts. As to the removal of oxygen, it was proved that zeolite catalysts had a functionality to remove oxygen as CO/sub x/ gas, and HDS catalysts had a high activity for hydrodeoxygenation. 10 references, 3 figures, 4 tables.

  15. Experimental and simulated propene isotherms on porous solids

    NASA Astrophysics Data System (ADS)

    Navarro, M. V.; Puértolas, B.; García, T.; Murillo, R.; Mastral, A. M.; Varela-Gandía, F. J.; Lozano-Castelló, D.; Cazorla-Amorós, D.; Bueno-López, A.

    2010-06-01

    The lack of treatment capacity of hydrocarbons by three-way catalysts during the "cold start" period creates an important environmental problem. During this period, the temperature of the three-way catalyst is too low for effective operation and cannot convert the hydrocarbons in the exhaust. 50-80% of the total hydrocarbon emissions are produced in this phase that accomplishes the first 60-120 s of the engine operation. In this study, the technology chosen to treat these emissions is the use of HC-traps, and molecular simulations are tested as a tool to reproduce the experimental adsorption behaviour of porous solids. Therefore, experimental and simulated adsorption isotherms of propene (model hydrocarbon) have been obtained for four different crystalline materials with distinctive framework structures (3D and 1D) and a variety of Si/Al ratios and cations (three zeolites: ZSM-5, BETA and Mordenite; and a silicoaluminophosphate molecular sieve: SAPO-5).

  16. Solvent effects in acid-catalyzed biomass conversion reactions.

    PubMed

    Mellmer, Max A; Sener, Canan; Gallo, Jean Marcel R; Luterbacher, Jeremy S; Alonso, David Martin; Dumesic, James A

    2014-10-27

    Reaction kinetics were studied to quantify the effects of polar aprotic organic solvents on the acid-catalyzed conversion of xylose into furfural. A solvent of particular importance is γ-valerolactone (GVL), which leads to significant increases in reaction rates compared to water in addition to increased product selectivity. GVL has similar effects on the kinetics for the dehydration of 1,2-propanediol to propanal and for the hydrolysis of cellobiose to glucose. Based on results obtained for homogeneous Brønsted acid catalysts that span a range of pKa values, we suggest that an aprotic organic solvent affects the reaction kinetics by changing the stabilization of the acidic proton relative to the protonated transition state. This same behavior is displayed by strong solid Brønsted acid catalysts, such as H-mordenite and H-beta. PMID:25214063

  17. Zeolite thermodynamics and kinetics. Final report for June 15, 1996 to June 15, 2000 to the U.S. Department of Energy, Geosciences Research Program, Office of Basic Energy Sciences on Grant No. DE-FG02-96ER14634

    SciTech Connect

    Barnes, H.L.; Wilkin, R.T.; Benning, L.G.

    2000-06-15

    This report summarizes results obtained on the thermodynamic and kinetic properties of zeolites. DOE funding supported the development of techniques of material preparation as well as experimental strategies and methods for measuring solubilities, hydration states, and rates of zeolite dissolution, precipitation, and nucleation. The hydrothermal experiments provided temperature-dependent solubility products, hydration states, and a set of standard free energies of formation for end-member Na-, K-, and Ca-clinoptilolite, mordenite, and analcime. Flow-through experimental methods were used to measure the rates of Na-clinoptilolite and analcime dissolution and precipitation as a function of reaction affinity to 250C. Finally, the experimental system was modified so that the clinoptilolite-to-analcime transformation was monitored, and its rates and mechanisms were evaluated.

  18. Fracture-lining minerals in the lower Topopah Spring Tuff at Yucca Mountain

    SciTech Connect

    Carlos, B.A.; Bish, D.L.; Chipera, S.J.

    1991-01-01

    Fracture-lining minerals in the lower Topopah Spring Member of the Paintbrush Tuff at Yucca Mountain, Nevada, are being examined to characterize potential flow paths within and away from the candidate repository horizon. Fracture coatings within this interval can be divided into five categories based on rock matrix and type of fracture. Fracture coatings in the densely welded tuff above the basal vitrophyre, near the candidate repository horizon, include (1) those related to lithophysal cavities; (2) mordenite and manganese oxides on nearly planar fractures; (3) later fracture coatings consisting of zeolites, smectite, and calcite. Fracture-coating minerals in the vitrophyre are fine-grained and consist of smectite and a variety of zeolites. The non- to partially-welded vitric and/or zeolitic stuff below the vitrophyre contains fractures mostly lined by cristobalite and clinoptilolite. 13 refs., 2 figs., 1 tab.

  19. First-Principles Calculation Study of Mechanism of Cation Adsorption Selectivity of Zeolites: A Guideline for Effective Removal of Radioactive Cesium

    NASA Astrophysics Data System (ADS)

    Nakamura, Hiroki; Okumura, Masahiko; Machida, Masahiko

    2013-02-01

    Zeolites have attracted attention in the reprocessing of radioactive nuclear waste because of their high selective affinity for radioisotopes of Cs. Very recently, their useful properties have been widely utilized in decontamination after the accident at the Fukushima Daiichi Nuclear Power Plants. In this study, we study the high selectivity in the Cs adsorption of zeolites using first-principles calculations and clarify the mechanism of the cation selectivity of zeolites. We obtain energy surfaces on all capture locations for Cs/Na ions inside the micropores of a zeolite, ``mordenite'', and find three crucial conditions for the highly ion-selective exchange of Na for Cs: i) micropores with a radius of ˜3 Å, ii) a moderate Al/Si ratio, and iii) a uniform distribution of Al atoms around each micropore. These insights suggest a guideline for developing zeolites with high Cs selectivity and for enhancing the cation selectivity in more general situations.

  20. The zeolite deposits of Greece

    USGS Publications Warehouse

    Stamatakis, M.G.; Hall, A.; Hein, J.R.

    1996-01-01

    Zeolites are present in altered pyroclastic rocks at many localities in Greece, and large deposits of potential economic interest are present in three areas: (1) the Evros region of the province of Thrace in the north-eastern part of the Greek mainland; (2) the islands of Kimolos and Poliegos in the western Aegean; and (3) the island of Samos in the eastern Aegean Sea. The deposits in Thrace are of Eocene-Oligocene age and are rich in heulandite and/or clinoptilolite. Those of Kimolos and Poliegos are mainly Quaternary and are rich in mordenite. Those of Samos are Miocene, and are rich in clinoptilolite and/or analcime. The deposits in Thrace are believed to have formed in an open hydrological system by the action of meteoric water, and those of the western Aegean islands in a similar way but under conditions of high heat flow, whereas the deposits in Samos were formed in a saline-alkaline lake.

  1. Changes in the Vibrational Spectra of Zeolites Due to Sorption of Heavy Metal Cations

    NASA Astrophysics Data System (ADS)

    Król, M.; Mozgawa, W.; Barczyk, K.; Bajda, T.; Kozanecki, M.

    2013-11-01

    This work presents the results of spectroscopic (MIR and Raman) studies of zeolite structures after immobilization of heavy metal cations from aqueous solutions. The sorption of Ag+, Cu2+, Cd2+, Pb2+, Zn2+, and Cr3+ ions has been conducted on zeolites belonging to different structural groups, i.e., sodium forms of natural chabazite, mordenite, ferrierite, and clinoptilolite, as well as on synthetic zeolite Y. Systematic changes in intensities and positions of the bands corresponding to the characteristic ring vibrations have been observed in the measured spectra. The most visible changes are observed in the FT-IR spectra of the samples in the range of 850-450 cm-1, and in the Raman spectra in the range of 600-250 cm-1. Depending on the zeolite structure, the bands, which can be regarded as a kind of indicator of ion exchange, were indentifi ed. For example, in the case of IR spectra, these bands are at 766, 703, 648, 578, and 506 cm-1 for zeolite Y, at 733 and 560 cm-1 for mordenite, at 675 cm-1 for clinoptilolite, etc. The degree of changes depends on both the type of cation and its concentration in the initial solution. This is connected with the way of binding of metal ions to the zeolite aluminosilicate framework, i.e., a proportion of the ion exchange and chemisorption in the process. Cations mainly undergoing ion exchange, such as Cd2+ or Pb2+, have the greatest impact on the character of the spectra. On the other hand, Cr3+ ions practically do not modify the spectra of zeolites. Results of IR and Raman spectroscopic studies have been compared with those obtained by atomic absorption spectroscopy (AAS), from which the proportion of ion exchange to chemisorption in the process and the effective cation exchange capacity of the individual samples have been estimated.

  2. Summary of the mineralogy-petrology of tuffs of Yucca Mountain and the secondary-phase thermal stability in tuffs

    SciTech Connect

    Bish, D.L.; Vaniman, D.T.; Byers, F.M. Jr.; Broxton, D.E.

    1982-11-01

    Yucca Mountain is composed of a thick sequence of silicic tuffs that are quite variable in degree of welding, alteration, and zeolitization. Tuff units above the water table are commonly devitrified or still vitric, with the exception of the zeolitized Pah Canyon Member in USW-G2. The devitrified tuffs above the water table commonly contain alkali feldspar, quartz, tridymite, and cristobalite, with minor smectite. The vitric tuffs are partly to wholly altered to sodium-calcium-saturated smectite. Below the water table are generally densely welded nonzeolitized tuffs and less densely welded zeolite-containing tuffs. The specific mineral assemblage present in Yucca Mountain tuffs has important implications in choosing a repository. The secondary phases clinoptilolite, mordenite, and smectite are very important because of their large cation sorption capacities. However, whereas densely welded tuffs containing no zeolite or glass are resistant to heating and do not dehydrate significantly, zeolitized, vitric, and smectite-containing horizons are very sensitive to minor increases in temperature. Smectites are particularly sensitive to changes in water vapor pressure and temperature, and temperature increases can lead to water evolution and large volume reductions. Similarly, clinoptilolite and mordenite begin to dehydrate below 100{sup 0}C, resulting in volume decreases. The exact effect of temperature on vitric tuffs is unclear. Under hydrothermal conditions the smectites gradually transform to nonexpanding, low sorption capacity illites, and there is evidence that this reaction has occurred in the deeper portions of USW-G2. Clinoptilolite transforms under hydrothermal conditions to analcime plus quartz with a concomitant volume decrease and water evolution. Again, there is evidence of this reaction occurring in Yucca Mountain tuffs at 80 to 100{sup 0}C.

  3. Development of Stable Solidification Method for Insoluble Ferrocyanides-13170

    SciTech Connect

    Ikarashi, Yuki; Masud, Rana Syed; Mimura, Hitoshi; Ishizaki, Eiji; Matsukura, Minoru

    2013-07-01

    The development of stable solidification method of insoluble ferrocyanides sludge is an important subject for the safety decontamination in Fukushima NPP-1. By using the excellent immobilizing properties of zeolites such as gas trapping ability and self-sintering properties, the stable solidification of insoluble ferrocyanides was accomplished. The immobilization ratio of Cs for K{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O saturated with Cs{sup +} ions (Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O) was estimated to be less than 0.1% above 1,000 deg. C; the adsorbed Cs{sup +} ions are completely volatilized. In contrast, the novel stable solid form was produced by the press-sintering of the mixture of Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O and zeolites at higher temperature of 1,000 deg. C and 1,100 deg. C; Cs volatilization and cyanide release were completely depressed. The immobilization ratio of Cs, under the mixing conditions of Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O:CP= 1:1 and calcining temperature: 1,000 deg. C, was estimated to be nearly 100%. As for the kinds of zeolites, natural mordenite (NM), clinoptilolite (CP) and Chabazite tended to have higher immobilization ratio compared to zeolite A. This may be due to the difference in the phase transformation between natural zeolites and synthetic zeolite A. In the case of the composites (K{sub 2-X}Ni{sub X/2}[NiFe(CN){sub 6}].nH{sub 2}O loaded natural mordenite), relatively high immobilization ratio of Cs was also obtained. This method using zeolite matrices can be applied to the stable solidification of the solid wastes of insoluble ferrocyanides sludge. (authors)

  4. Studies of anions sorption on natural zeolites.

    PubMed

    Barczyk, K; Mozgawa, W; Król, M

    2014-12-10

    This work presents results of FT-IR spectroscopic studies of anions-chromate, phosphate and arsenate - sorbed from aqueous solutions (different concentrations of anions) on zeolites. The sorption has been conducted on natural zeolites from different structural groups, i.e. chabazite, mordenite, ferrierite and clinoptilolite. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA(+)) and organo-zeolites were obtained. External cation exchange capacities (ECEC) of organo-zeolites were measured. Their values are 17mmol/100g for chabazite, 4mmol/100g for mordenite and ferrierite and 10mmol/100g for clinoptilolite. The used initial inputs of HDTMA correspond to 100% and 200% ECEC of the minerals. Organo-modificated sorbents were subsequently used for immobilization of mentioned anions. It was proven that aforementioned anions' sorption causes changes in IR spectra of the HDTMA-zeolites. These alterations are dependent on the kind of anions that were sorbed. In all cases, variations are due to bands corresponding to the characteristic Si-O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolites). Alkylammonium surfactant vibrations have also been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO4(2-), AsO4(3-) and PO4(3-) ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of anions were determined by spectrophotometric method. PMID:25002191

  5. Evenly-spaced columns in the Bishop Tuff as relicts of hydrothermal convection

    NASA Astrophysics Data System (ADS)

    Randolph-Flagg, N. G.; Breen, S. J.; Hernandez, A.; Self, S.; Manga, M.

    2015-12-01

    A few square km of the Bishop Tuff in eastern California, USA have evenly spaced erosional columns. These columns are more resistant to erosion due to the precipitation of the low-temperature zeolite (120-200 ºC), mordenite, which is not found in the surrounding tuff. Similar features observed in the Bandelier Tuff were hypothesized to form when cold water from above infiltrated into the still-hot tuff interior. This water would become gravitationally unstable and produced convection with steam upwellings and liquid water downwellings. These downwellings became cemented with mordenite while the upwellings were too dry for chemical reactions. We use two methods to quantitatively assess this hypothesis. First, scaling that ignores the effects of latent heat and mineral precipitation suggests the Rayleigh number (Ra, a measure of convective vigor) for this system is ~103 well above the critical Ra of 4π2. Second, to account for the effect of multiphase flow and latent heat, we use two-dimensional numerical models in the finite difference code HYDROTHERM. We find that the geometry of flow is consistent with field observations and confirm that geometry is sensitive to permeability and topography. These tests suggest a few things about low-pressure hydrothermal systems. 1) The geometry of at least some convection appears to be broadly captured by linear stability theory that ignores reactive transport, heterogeneity of host rock, and the effects of latent heat. 2) Topographic flow sets the wavelength of convection meaning that these columns formed somewhere without topography—probably a lake. Finally, these observations imply a wet paleoclimate in the Eastern Sierra namely that, in the aftermath of the Long Valley eruption, either rain or snow was able to pool in the caldera before the tuff cooled on the order of a hundred years after the eruption.

  6. Environmental effect and genetic influence: a regional cancer predisposition survey in the Zonguldak region of Northwest Turkey

    NASA Astrophysics Data System (ADS)

    Kadir, Selahattin; Önen-Hall, A. Piril; Aydin, S. Nihal; Yakicier, Cengiz; Akarsu, Nurten; Tuncer, Murat

    2008-03-01

    The Cretaceous-Eocene volcano-sedimentary units of the Zonguldak region of the western Black Sea consist of subalkaline andesite and tuff, and sandstone dominated by smectite, kaolinite, accessory chlorite, illite, mordenite, and analcime associated with feldspar, quartz, opal-CT, amphibole, and calcite. Kaolinization, chloritization, sericitization, albitization, Fe-Ti-oxidation, and the presence of zeolite, epidote, and illite in andesitic rocks and tuffaceous materials developed as a result of the degradation of a glass shards matrix, enclosed feldspar, and clinopyroxene-type phenocrysts, due to alteration processes. The association of feldspar and glass with smectite and kaolinite, and the suborientation of feldspar-edged, subparallel kaolinite plates to fracture axes may exhibit an authigenic smectite or kaolinite. Increased alteration degree upward in which Al, Fe, and Ti are gained, and Si, Na, K, and Ca are depleted, is due to the alteration following possible diagenesis and hydrothermal activities. Micromorphologically, fibrous mordenite in the altered units and the presence of needle-type chrysotile in the residential buildings in which cancer cases lived were detected. In addition, the segregation pattern of cancer susceptibility in the region strongly suggested an environmental effect and a genetic influence on the increased cancer incidence in the region. The most likely diagnosis was Li-Fraumeni syndrome, which is one of the hereditary cancer predisposition syndromes; however, no mutations were observed in the p53 gene, which is the major cause of Li-Fraumeni syndrome. The micromorphology observed in the altered units in which cancer cases were detected may have a role in the expression of an unidentified gene, but does not explain alone the occurrence of cancer as a primary cause in the region.

  7. Preparation for kinetic measurements on the silicates of the Yucca Mountain potential repository. [Final report], June 15, 1993--September 30, 1993

    SciTech Connect

    1993-12-31

    Part 1, ``The Preparation of Clinoptilolite, Mordenite and Analcime,`` summarized progress made during the contract period on preparing Na-end member clinoptilolite, mordenite, and analcime. The objective is to use the prepared zeolites to determine rates of dissolution and precipitation in laboratory flow-through systems in both this lab to 350 C and by the geochemists at Yale University to about 80 C. Because clinoptilolite represents the most complicated phase of these three zeolites and it is most abundant at Yucca Mountain, the authors have concentrated most of their efforts on its preparation. They have collected, high-concentration natural clinoptilolite samples. A hindered settling technique that takes advantage of the relatively low specific gravity of clinoptilolite coupled with ultrasonic cleaning in deionized water has been employed. This material is now a mixed Na-K zeolite which must then be converted to the pure Na-end member composition. In Part 2, ``Draft Manuscript on the Heterogeneous Kinetics of Cristobalite,`` experiments on the rates of reactions of dissolution and precipitation of cristobalite were carried at 150--300 C. Results show that cristobalite may precipitate from hydrothermal solution if the concentration of Si(OH){sub 4} exceeds that at quartz saturation and is less than that of amorphous silica saturation and if there are cristobalite nuclei present. Such nuclei may occur where there has been devitrification of volcanic glasses, for example. Cristobalite has refused to crystallize in the absence of such nuclei. Steady state concentrations were reached experimentally after starting at 150 {degree} with initially supersaturated solutions and at 200 C starting with either supersaturated or undersaturated solutions. From the steady state conditions, equilibrium constants can be derived.

  8. Hydrothermal alteration in research drill hole Y-3, Lower Geyser Basin, Yellowstone National Park, Wyoming

    USGS Publications Warehouse

    Bargar, Keith E.; Beeson, Melvin H.

    1985-01-01

    Y-3, a U.S. Geological Survey research diamond-drill hole in Lower Geyser Basin, Yellowstone National Park, Wyoming, reached a depth of 156.7 m. The recovered drill core consists of 42.2 m of surficial (mostly glacial) sediments and two rhyolite flows (Nez Perce Creek flow and an older, unnamed rhyolite flow) of the Central Plateau Member of the Pleistocene Plateau Rhyolite. Hydrothermal alteration is fairly extensive in most of the drill core. The surficial deposits are largely cemented by silica and zeolite minerals; and the two rhyolite flows are, in part, bleached by thermal water that deposited numerous hydrothermal minerals in cavities and fractures. Hydrothermal minerals containing sodium as a dominant cation (analcime, clinoptilolite, mordenite, Na-smectite, and aegirine) are more abundant than calcium-bearing minerals (calcite, fluorite, Ca-smectite, and pectolite) in the sedimentary section of the drill core. In the volcanic section of drill core Y-3, calcium-rich minerals (dachiardite, laumontite, yugawaralite, calcite, fluorite, Ca-smectite, pectolite, and truscottite) are predominant over sodium-bearing minerals (aegirine, mordenite, and Na-smectite). Hydrothermal minerals that contain significant amounts of potassium (alunite and lepidolite in the sediments and illitesmectite in the rhyolite flows) are found in the two drill-core intervals. Drill core y:.3 also contains hydrothermal silica minerals (opal, [3-cristobalite, chalcedony, and quartz), other clay minerals (allophane, halloysite, kaolinite, and chlorite), gypsum, pyrite, and hematite. The dominance of calcium-bearing hydrothermal minerals in the lower rhyolitic section of the y:.3 drill core appears to be due to loss of calcium, along with potassium, during adiabatic cooling of an ascending boiling water.

  9. Mineralogic summary of Yucca Mountain, Nevada

    SciTech Connect

    Bish, D.L.; Vaniman, D.T.

    1985-10-01

    Quantitative x-ray powder diffraction analysis of tuffs and silicic lavas, using matrix-flushing techniques, has been used to obtain a model of three-dimensional mineral distributions at Yucca Mountain, Nevada. This method of analysis is especially useful in tuff, where the most abundant phases are commonly too fine grained for optical determination. The three-dimensional distributions of primary glass and of tridymite are particularly well constrained. Vitric nonwelded glasses occur above and below the welded devitrified Topopah Spring Member, but the glass in the lower nonwelded vitric zone is progressively altered to zeolites to the east where the zone is closer to the static water level. The zeolites clinoptilolite, mordenite, heulandite, and erionite have all been found at Yucca Mountain, but only mordenite and clinoptilolite are abundant and can be mapped between many drill holes and at many depths. Heulandite distribution is also mappable, but only below the densely welded devitrified part of the Topopah Storing Member. Erionite has been confirmed only once, as a fracture coating. There is a fairly continuous smectite-rich interval immediately above the basal vitrophyre of the Topopah Spring Member, but no evidence suggests that the smectites can provide information on the paleogroundwater table. There are at least four mappable zeolitized zones in Yucca Mountain, and the thicker zones tend to coincide with intervals that retained glass following early tuff devitrification. Problems in extrapolation occur where zones of welding pinch out. No phillipsite has been found, and some samples previously reported to contain phillipsite or erionite were reexamined with negative results. The deeper alteration to albite and analcime was not sampled in every drill hole, and the distribution of these phases is difficult to map.

  10. Revised mineralogic summary of Yucca Mountain, Nevada

    SciTech Connect

    Bish, D.L.; Chipera, S.J.

    1989-03-01

    We have evaluated three-dimensional mineral distribution at Yucca Mountain, Nevada, using quantitative x-ray powder diffraction analysis. All data were obtained on core cuttings, or sidewall samples obtained from drill holes at and around Yucca Mountain. Previously published data are included with corrections, together with new data for several drill holes. The new data presented in this report used the internal standard method of quantitative analysis, which yields results of high precision for the phases commonly found in Yucca Mountain tuffs including opal-CT and glass. Mineralogical trends with depth previously noted are clearly shown by these new data. Glass occurrence is restricted almost without exception to above the present-day static water level (SWL), although glass has been identified below the SWL in partially zeolitized tuffs. Silica phases undergo well-defined transitions with depth, with tridymite and cristobalite occurring only above the SWL, opal-CT occurring with clinoptilolite-mordenite tuffs, and quartz most abundant below the SWL. Smectite occurs in small amounts in most samples but is enriched in two distinct zones. These zones are at the top of the vitric nonwelded base of the Tiva Canyon Member and at the top of the basal vitrophyre of the Topopah Spring Member. Our data support the presence of several zones of mordenite and clinoptilolite-heulandite as shown previously. New data on several deep clinoptililite-heulandite samples coexisting with analcime show that they are heulandite. Phillipsite has not been found in any Yucca Mountain samples, but erionite and chabazite have been found once in fractures. 21 refs., 17 figs.

  11. Analysis of the biological and chemical reactivity of zeolite-based aluminosilicate fibers and particulates.

    PubMed Central

    Fach, Estelle; Waldman, W James; Williams, Marshall; Long, John; Meister, Richard K; Dutta, Prabir K

    2002-01-01

    Environmental and/or occupational exposure to minerals, metals, and fibers can cause lung diseases that may develop years after exposure to the agents. The presence of toxic fibers such as asbestos in the environment plus the continuing development of new mineral or vitreous fibers requires a better understanding of the specific physical and chemical features of fibers/particles responsible for bioactivity. Toward that goal, we have tested aluminosilicate zeolites to establish biological and chemical structure-function correlations. Zeolites have known crystal structure, are subject to experimental manipulation, and can be synthesized and controlled to produce particles of selected size and shape. Naturally occurring zeolites include forms whose biological activity is reported to range from highly pathogenic (erionite) to essentially benign (mordenite). Thus, we used naturally occurring erionite and mordenite as well as an extensively studied synthetic zeolite based on faujasite (zeolite Y). Bioactivity was evaluated using lung macrophages of rat origin (cell line NR8383). Our objective was to quantitatively determine the biological response upon interaction of the test particulates/fibers with lung macrophages and to evaluate the efficacy of surface iron on the zeolites to promote the Fenton reaction. The biological assessment included measurement of the reactive oxygen species by flow cytometry and chemiluminescence techniques upon phagocytosis of the minerals. The chemical assessment included measuring the hydroxyl radicals generated from hydrogen peroxide by iron bound to the zeolite particles and fibers (Fenton reaction). Chromatography as well as absorption spectroscopy were used to quantitate the hydroxyl radicals. We found that upon exposure to the same mass of a specific type of particulate, the oxidative burst increased with decreasing particle size, but remained relatively independent of zeolite composition. On the other hand, the Fenton reaction

  12. Studies on transition metals and alloy Fischer-Tropsch catalysts, their electronic and bulk properties. (I: Fe/MnO; II: Fe/TiO/sub 2/; III: Fe/Mord. ). Final report, July 1, 1982-September 30, 1983

    SciTech Connect

    Mulay, L.N.

    1983-11-01

    The objectives were: (1) to characterize samples D1, 10% FeO/90% MnO, and D2, 48% FeO/52% MnO, under varying conditions of reduction (at 250/sup 0/C or 350/sup 0/C in H/sub 2/) and of syngas reaction 1:1 of CO:H/sub 2/ at 290/sup 0/C) and in some cases use CO only for reduction and to identify species by Moessbauer Spectroscopy and Magnetization (sigma/sub s) measurement; (2) similarly, to see if there is any metal (oxide)/support (Mordenite) interaction by the same techniques. The characterization was carried out with above techniques and the kinetic results for syngas were obtained on the above systems mostly at PETC. During reduction of Fe-oxide/Mn-oxide an intermediate Mn-ferrite phase was detected. After reduction, species such as Fe/sup 0/+Fe/sup 3 +/+Fe/sup 2 +/ in varying total proportions (45% at 290/sup 0/C and Fe/sup 0/+Fe/sup 2 +/ 75% were found at 350/sup 0/C). Syngas conversion showed Fe-carbides (Fe/sub 2/C/sub 2/+Fe/sub 3/C) depending on the reaction conditions, and the composition of D/sub 1/ and D/sub 2/. With the fresh ..gamma..-Fe/sub 2/O/sub 3/ (identified by Moessbauer) on Mordenites with varying ratios of SiO/sub 2//Al/sub 2/O/sub 3/, a decrease in (sigma/sub s/) was found with lowering of the ratios from 60 to 17. At 17% ratio (sigma/sub s/) was smallest and the change in the isomer shift was maximum, which established an interaction with the Broensted cities. 24 figures.

  13. The interactions of methyl tert-butyl ether on high silica zeolites: a combined experimental and computational study.

    PubMed

    Sacchetto, V; Gatti, G; Paul, G; Braschi, I; Berlier, G; Cossi, M; Marchese, L; Bagatin, R; Bisio, C

    2013-08-28

    In this work, the interactions of methyl tert-butyl ether (MTBE) on different dealuminated high silica zeolites were studied by means of both experimental and computational approaches. Zeolites with different textural and surface features were selected as adsorbents and the effect of their physico-chemical properties (i.e. pore size architecture and type and amount of surface OH sites) on sorption capacity were studied. High silica mordenite (MOR) and Y zeolites (both with a SiO2/Al2O3 ratio of 200) and ZSM-5 solid (SiO2/Al2O3 ratio of 500) were selected as model sorbents. By combining FTIR and SS-NMR (both (1)H and (13)C CPMAS NMR) spectroscopy it was possible to follow accurately the MTBE adsorption process on highly defective MOR characterized by a high concentration of surface SiOH groups. The adsorption process is found to occur in different steps and to involve isolated silanol sites, weakly interacting silanols, and the siloxane network of the zeolite, respectively. H-bonding and van der Waals interactions occurring between the mordenite surface and MTBE molecules were modeled by DFT calculations using a large cluster of the MOR structure where two adjacent side-pockets were fused in a large micropore to simulate a dealumination process leading to silanol groups. This is the locus where MTBE molecules are more strongly bound and stabilized. FTIR spectroscopy and gravimetric measurements allowed determination of the interaction strength and sorption capacities of all three zeolites. In the case of both Y and MOR zeolites, medium-weak H-bonding with isolated silanols (both on internal and external zeolite surfaces) and van der Waals interactions are responsible for MTBE adsorption, whereas ZSM-5, in which a negligible amount of surface silanol species is present, displays a much lower amount of adsorbed MTBE retained mainly through van der Waals interactions with zeolite siloxane network. PMID:23860729

  14. Minerals in fractures of the unsaturated zone from drill core USW G-4, Yucca Mountain, Nye County, Nevada

    SciTech Connect

    Carlos, B.A.

    1985-05-01

    The mineralogy of fractures in drill core USW G-4, from a depth of nearly 800 ft to the static water level (SWL) at 1770 ft, was examined to determine the sequence of deposition and the identity of minerals that might be natural barriers to radionuclide migration from a nuclear waste repository. Mordenite was found to be present, though not abundant, at the top of the interval sampled (the top of the lower lithophysal zone of the Topopah Spring Member of the Paintbrush Tuff). Heulandite occurs from about 1245 to 1378 ft; below 1378 ft, clinoptilolite rather than heulandite occurs alone or with mordenite. Smectite in fractures is abundant only in the vitrophyre of the Topopah Spring Member of the Paintbrush Tuff and at the top of the Prow Pass member of the Crater Flat Tuff. The unsaturated zone below 800 ft can be divided into three rock types: devitrified, glassy, and zeolitized host rock. Fracture-lining zeolites for each of these three rock types differ in mineralogy and morphology. Similarities, between fracture mineralogy and host-rock alteration in the nonwelded zeolitic units of the Topopah Spring Member suggest that this zone was once below the water table. The difference between microcrystalline ({ge}.01 mm) fracture coatings in the vitric zone and the mostly cryptocrystalline (<<0.01 mm) fracture coatings in the zeolitic zone also suggests that the conditions under which these two types of linings formed were different. Nonwelded glass shards preserved in the host rock above the zeolite-mineral transition in the fractures indicate that the water table was never higher than the lithic-rich base of the Topopah Spring Member in the vicinity of USW G-4. Fracture linings in the zeolitic Topopah Spring Member are clinoptilolite, but the crystal size (0.01 to 0.02 mm) is closer to that of heulandite in fractures of the vitric zone above it than to clinoptilolite in the Tuff of Calico Hills below. 21 refs., 48 figs., 2 tabs.

  15. Complete Phase I Tests As Described in the Multi-lab Test Plan for the Evaluation of CH3I Adsorption on AgZ

    SciTech Connect

    Bruffey, S. H.; Jubin, R. T.

    2014-09-30

    Silver-exchanged mordenite (AgZ) has been identified as a potential sorbent for iodine present in the off-gas streams of a used nuclear fuel reprocessing facility. In such a facility, both elemental and organic forms of iodine are released from the dissolver in gaseous form. These species of iodine must be captured with high efficiency for a facility to avoid radioactive iodine release above regulatory limits in the gaseous effluent of the plant. Studies completed at Idaho National Laboratory (INL) examined the adsorption of organic iodine in the form of CH3I by AgZ. Upon breakthrough of the feed gas through the sorbent bed, elemental iodine was observed in the effluent stream, despite the fact that the only source of iodine in the system was the CH3I in the feed gas.1 This behavior does not appear to have been reported previously nor has it been independently confirmed. Thus, as a result of these prior studies, multiple knowledge gaps relating to the adsorption of CH3I by AgZ were identified, and a multi-lab test plan, including Oak Ridge National Laboratory (ORNL), INL, Pacific Northwest National Laboratory (PNNL), and Sandia National Laboratories, was formulated to address each in a systematic way.2 For this report, the scope of work for ORNL was further narrowed to three thin-bed experiments that would characterize CH3I adsorption onto AgZ in the presence of water, NO, and NO2. Completion of these three-thin bed experiments demonstrated that organic iodine in the form of CH3I was adsorbed by reduced silver mordenite (Ag0Z) to a 50% higher loading than that of I2 when adsorbed from a dry air stream. Adsorption curves suggest different adsorption mechanisms for I2 and CH3I. In the presence of NO and NO2 gas, the loading of CH3I onto Ag0Z is suppressed and may be reversible. Further, the presence of NO and NO2 gas appears to oxidize CH3I to I2; this is indicated by an adsorption curve similar to that of I2 on Ag0Z. Finally, the loss of organic iodine loading

  16. Probing zeolite syntheses to determine natural occurances of zeolites

    NASA Astrophysics Data System (ADS)

    Chen, H.; Song, S.; Fang, J.

    2003-12-01

    In this study, zeolites were synthesized from different glasses to probe the occurrence of zeolites in nature. The experiments were carried out with synthetic glass systems of Na2O.Al2O3.nSiO2, CaO.Al2O3.nSiO2, xNa2O.(1-x)CaO.Al2O3.nSiO2 and xNa2O.(1-x)K2O.Al2O3.6SiO2 in alkaline solutions of NaOH, KOH, Na2CO3, NH4OH, NaOH (+) NaCl and NaOH (+) KOH at temperatures ranging from 110›J to 210›J and with autogeneous pressures in the autoclaves. Synthetic products were examined by an X-ray powder diffractometer, a scanning electron microscopy with an energy dispersive spectrometer, and an electron microprobe. The minerals synthesized included zeolites, i.e., thomsonite, gismondine, amicite, garronite, gobbinsite, analcime, phillipsite, merlinoite, chabazite and mordenite; artificial synthetic zeolites, and feldspars. Chemical analyses indicated that the composition of synthetic zeolites is profoundly influenced by the composition of the initial glasses, especially the SiO2/Al2O3 ratios and cations. On the other hand, the influence of Na+ and K+ have over the formation of zeolites in solution, other ions, such as CO32- were involved in the preventing of the formation of Ca-zeolites. Comparing the experimental results with natural occurrences suggests that thomsonite, gismondine and amicite are usually found in ultrabasic and basic rocks; garronite and gobbinsite in basic to intermediate rocks; analcime, phillipsite, and chabazite in basic to acid rocks; merlinoite in high-potassium rocks; and mordenite in acid rocks. In addition, Ca-zeolites including thomsonite, gismondine and garronite are favored in fresh water environments, and alkali zeolites including gobbinsite, phillipsite, and analcime are most abundant in saline lake and deep sea conditions.

  17. Hydrothermal alteration of a rhyolitic hyaloclastite from Ponza Island, Italy

    NASA Astrophysics Data System (ADS)

    Ylagan, Robert F.; Altaner, Stephen P.; Pozzuoli, Antonio

    1996-12-01

    A rhyolitic hyaloclastite from Ponza island, Italy, has been hydrothermally altered producing four distinct alteration zones based on XRD and field textures: (1) non-pervasive argillic zone; (2) propylitic zone; (3) silicic zone; and (4) sericitic zone. The unaltered hyaloclastite is a volcanic breccia with clasts of vesiculated obsidian in a matrix of predominantly pumice lapilli. Incomplete alteration of the hyaloclastite resulted in the non pervasive argillic zone, characterized by smectite and disordered opal-CT. Obsidian clasts, some pumice lapilli, and pyrogenic plagioclase and biotite are unaltered. Smectite has an irregular flakey morphology, although euhedral particles are occasionally observed. The propylitic zone is characterized by mixed-layer illite/smectite (I/S) with 10 to 85% illite (I), mordenite, opal-C and authigenic K-feldspar (akspar). The matrix of the hyaloclastite is completely altered and obsidian clasts are silicified; however, plagioclase and biotite phenocrysts remain unaltered. Flakey I/S replaces pumice, and mordenite, akspar and silica line and fill pores. I/S particles are composed predominantly of subequant plates and euhedral laths. The silicic zone is characterized by highly illitic I/S with ≥ 90% I, quartz, akspar and occasional albite. In this zone the matrix and clasts are completely altered, and pyrogenic plagioclase shows significant alteration. Illitic I/S has a euhedral lath-like morphology. In the sericitic zone the hyaloclastite altered primarily to illitic I/S with ≥ 66% I, quartz, and minor akspar and pyrite. Clay minerals completely replace pyrogenic feldspars and little evidence remains of the original hyaloclastite texture. Unlike other zones, illitic I/S is fibrous and pure illite samples are composed of euhedral laths and hexagonal plates. The temperatures of hydrothermal alteration likely ranged from 30 to 90 °C for the argillic zone, from 110 to 160 °C for the propylitic zone, from 160 to 270 °C for the

  18. Radium-thorium disequilibrium and zeolite-water ion exchange in a Yellowstone hydrothermal environment

    SciTech Connect

    Sturchio, N.C.; Bohlke, J.K. ); Binz, C.M. )

    1989-05-01

    Whole rock samples of hydrothermally altered Biscuit Basin rhyolite from Yellowstone drill cores Y-7 and Y-8 were analyzed for {sup 226}Ra and {sup 230}Th to determine the extent of radioactive disequilibrium and its relation to the rates and mechanisms of element transport in the shallow portion of an active hydrothermal system. The ({sup 226}Ra/{sup 230}Th) activity ratios range from 0.73 to 1.46 and are generally correlated with Th-normalized Ba concentrations (Ba{sub N}). Compositions of clinoptilolite and mordenite in these samples are consistent with ion exchange equilibrium between zeolites and coexisting thermal waters. Average K{sup Ba}{sub d mineral-water} values are 1.0 {center dot} 10{sup 5} mL/g for clinoptilolite and 1.4 {center dot} 10{sup 4} mL/g for mordenite. Apparent diffusivities through matrix porosity estimated for R and Ba range from {approximately}10{sup {minus}12} to {approximately}10{sup {minus}10} cm{sup 2} s{sup {minus}1} in thoroughly zeolitic rhyolite; these rates of diffusion are too low to account for the observed distance scale of ({sup 226}Ra/{sup 230}Th) disequilibrium. The correlated values of ({sup 226}Ra/{sup 230}Th) disequilibrium and Ba{sub N} represent zeolite-water ion exchange equilibrium that is caused by porous flow of water through the rock matrix and by the relatively rapid diffusion of cations within the zeolite lattices. A water flux of at least {approximately}2.5 (cm{sup 3}{sub water}/cm{sup 3}{sub rock}) yr{sup {minus}1} is required to produce measurable ({sup 226}Ra/{sup 230}Th) disequilibrium, whereas at least {approximately}23 (cm{sup 3}{sub water}/cm{sup 3}{sub rock}) yr{sup {minus}1} is required for the sample exhibiting the most extreme ({sup 226}Ra/{sup 230}Th) disequilibrium; these fluxes are much higher than those that can be inferred from net mass transfers of stable species.

  19. Comparison of silver sorbents for application to radioiodine control at the PUREX process facility modification. [Iodine 129

    SciTech Connect

    Scheele, R.D.; Burger, L.L.; Halko, B.T.

    1988-09-01

    In continued support of the design of the gaseous radioiodine control system for the PUREX Process Facility Modification (PFM), the Pacific Northwest Laboratory (PNL) conducted laboratory-scale measurements of the performance of four state-of-the-art sorbents for radioiodine in the dissolver offgas (DOG) of a nuclear reprocessing plant. The PFM is a new head-end treatment plant being designed by Westinghouse Hanford Company (WHC) for the PUREX Plant at the Hanford Site. The experiments performed measured the iodine effluent concentration from Norton silver mordenite (NAgZ), Linde silver mordenite (LAgZ), Linde silver faujasite (AgX), and silver nitrate-impregnated silicic acid (AgNO/sub 3/Si) during simulated normal operating conditions in the PFM after three shutdown/startup cycles, and during standby. At normal operating conditions the input gas is expected to have a dew point of 35/degree/C to 40/degree/C and contain 0.1 ..mu..mol I/L, 1 vol% NO, and 1 vol% NO /sub 2/. The sorbent bed would be at 150/degree/C. A shutdown/startup cycle consisted of eliminating iodine and NO/sub x/ from the input gas, cooling the bed to room temperature, stopping gas flow, and restarting the system. During standby conditions the input gas contained no iodine or NO/sub x/, the dew point was at 30/degree/C to 35/degree/C, and the bed temperature remained at 150/degree/C. This experimental study showed that 20 cm beds of NAgZ, LAgZ, and 18 wt% silver AgX could load up to 0.25 mmol I/g sorbent and routinely reduce the iodine concentration in a simulated PFM DOG from 0.1 ..mu..mol I/L to less than the target level of 10/sup /minus/5/ ..mu..mol I/L. In contrast, the AgNO/sub 3/Si unexpectedly failed to achieve this required level of performance, reducing the concentration on a routine basis only to 10/sup /minus/4/ to 10/sup /minus/2/ ..mu..mol I/L. 5 refs., 14 figs., 6 tabs.

  20. Investigation on NOx adsorption in [M‧]-MAPO-5 (M = Si, Ti; M‧ = Ag, Cu) by density functional theory calculation

    NASA Astrophysics Data System (ADS)

    Liu, Jiexiang; Zhang, Xiaoguang

    2013-01-01

    NO, N2O and NO2 adsorption in [M‧]-MAPO-5 (M = Si, Ti; M‧ = Ag, Cu) models of the modified aluminophosphate molecular sieves was investigated by density functional theory (DFT) method. The equilibrium structural parameters and adsorption energies were obtained and compared. The structural parameters of NO and NO2 in the adsorbed state had a distinct change than that of N2O compared to their free gas state. [M‧]-MAPO-5 was more effective for the activation of NOx molecule compared to [M‧]-AlMOR (M‧ = Ag, Cu) models of the modified mordenite in our previous studies. The adsorption energies data indicated that adsorption strength of NOx followed the decreasing order of NO2 > NO > N2O. And adsorption complexes in η1-N mode were much stabler than that in η1-O mode, which was similar to that in [M‧]-AlMOR. [Cu]-MAPO-5 had a much stronger adsorption for NOx than [Ag]-MAPO-5. And [M‧]-SiMOR had a little stronger adsorption for NOx than [M‧]-TiMOR. Furthermore, the resistance capabilities of [M‧]-MAPO-5 to SO2, H2O and O2 were studied and analyzed. The interaction mechanism of NOx adsorption in [M‧]-MAPO-5 was also discussed by natural bond orbital (NBO) analysis, which was in reasonable agreement with the adsorption interaction strengths.

  1. Fixed-bed adsorption of toluene on high silica zeolites: experiments and mathematical modelling using LDF approximation and a multisite model.

    PubMed

    Brodu, Nicolas; Sochard, Sabine; Andriantsiferana, Caroline; Pic, Jean-Stéphane; Manero, Marie-Hélène

    2015-01-01

    The adsorption of toluene (TOL) as a target volatile organic compound has been studied experimentally and modelled on various hydrophobic zeolites: Faujasite (FAU), ZSM-5 (Z) and Mordenite (MOR). The influence of the nature of the compensating cation (H+ or Na+) has also been investigated for ZSM-5 zeolite, which is known to possess three kinds of adsorption sites (sinusoidal channels, straight channels and intersections). Type I isotherms observed on FAU, Na-Z and MOR fitted well with the Langmuir model. A deviation from a type I isotherm was observed for H-Z, because of the structure of this zeolite. The Successive Langmuir Model was more successful to fit the 'bump' of the experimental curve than the Double Langmuir. Classical shapes were found for MOR, FAU and Na-Z breakthrough curves that were fitted with good accuracy using the Linear Driving Force (LDF) approximation. In the case of H-Z, a change of profile was observed during the dynamic adsorption and the differences seen between the Na-Z and H-Z behaviours were explained by the strong interactions between Na+ and adsorbed TOL at the intersection sites. The Na+ cations prevented reorientation of TOL molecules at the intersection and thereby avoided the filling of the sinusoidal channel segments. Thus, a specific model was developed for fitting the breakthrough curve of H-Z. The model developed took into account these two types of adsorption sites with the overall uptake for each site being given by an LDF approximation. PMID:25624172

  2. Mineral precipitation on modern siliciclastic tidal flats colonized by microbial mats

    NASA Astrophysics Data System (ADS)

    Cuadrado, Diana G.; Carmona, Noelia B.; Bournod, Constanza N.

    2012-10-01

    The preservation and cementation of sedimentary structures under the influence of microorganisms in siliciclastic environments have been poorly studied in contrast to carbonatic settings, where they have been extensively investigated. Whereas in carbonatic environments, microbial mat-induced precipitation of calcium carbonate results in a cementation process producing a quick lithification, in siliciclastic environments other minerals would act as cement. The focus of this paper is to document the presence of authigenic minerals within a biosedimentary fabrics and the possible link of these minerals with the extensive microbial mats that colonize the tidal flat of the temperate Bahía Blanca estuary. "Anoxic" minerals (e.g. pyrite) and authigenic zeolites such as analcime, clinoptilolite, mordenite, phillipsite and chabazite were recognized through SEM and EDX analyses. These minerals were most likely formed by alteration of volcanic ash, which is present in this tidal flat and also silica may result from dissolution of frustules of benthic diatoms. Minerals precipitated in this setting are significant as they would act as early cement in the eogenesis, enhancing the preservation of sedimentary and biogenic structures.

  3. Kinetics of the adsorption of radionuclides on tuff from Yucca Mountain

    SciTech Connect

    Rundberg, R.S.

    1984-12-31

    The sorption of simple cations in tuff is dominated by adsorption on aluminosilicates that have charged surfaces, such as zeolites and clays. The most significant sorbing minerals present in Nevada tuff are clinoptilolite, heulandite, mordenite, and montmorillonite. The kinetics of sorption on tuffs containing the minerals clinoptilolite and montmorillonite has been determined by studying the uptake of strontium, cesium, and barium on thin tuff wafers. The rate constants for uptake of these elements on tuff are consistent with a model of sorption that is diffusion limited but where diffusion occurs in two stages. First the cations diffuse into the rock through the water-filled pore space. Next, the cations must diffuse into the much narrower channels within the aluminosilicate crystals. After they are within the zeolite framework or between the clay planes, the cations may rapidly sorb on the negatively charged surfaces. The actinide elements have a time constant for the apparent sorption that is inconsistent with this model and may have a radically different mechanism of removal from solution. 12 references, 4 tables.

  4. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: the influence of zeolite chemical surface characteristics.

    PubMed

    Alejandro, Serguei; Valdés, Héctor; Manéro, Marie-Hélène; Zaror, Claudio A

    2014-06-15

    In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity. PMID:24794812

  5. Zeolite stability constraints on radioactive waste isolation in zeolite-bearing volcanic rocks

    SciTech Connect

    Smyth, J.R.

    1982-12-31

    Silicic tuffs of the southern Great Basin and basalts of the Columbia River Plateau are under investigation as potential host rocks for high- and intermediate-level radioactive wastes. Non-welded and partially welded tuffs may contain major amounts (> 50%) of the zeolite minerals: clinoptilolite, mordenite, and analcime. Densely welded tuffs and some basalt flows may contain clinoptilolite as fracture filling which limits permeability of these rocks. The cation exchange properties of these zeolite minerals allow them to pose a natural barrier to the migration of cationic species of various radionuclides in aqueous solutions. However, these minerals are unstable at elevated temperatures and at low water vapor pressures, and they may break down either by reversible dehydration or by irreversible mineralogical reactions. All of the breakdown reactions occurring with increased temperature involve a net volume reduction and evolution of fluids. Thus, they may provide both a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere. These reactions may be avoided by keeping zeolite-bearing horizons saturated with water and below about 85{sup 0}C. This may restrict allowable gross thermal loadings in radioactive waste repositories in zeolite-bearing volcanic rocks. 3 figures.

  6. Characterization of Binary Ag-Cu Ion Mixtures in Zeolites: Their Reduction Products and Stability to Air Oxidation

    SciTech Connect

    Fiddy, Steven; Petranovskii, Vitalii; Ogden, Steve; Iznaga, Inocente Rodriguez

    2007-02-02

    A series of Ag+-Cu2+ binary mixtures with different Ag/Cu ratios were supported on mordenite with different Si/Al ratios and were subsequently reduced under hydrogen in the temperature range 323K - 473K. Ag and Cu K-edge X-ray Absorption Spectroscopy (XAS) was conducted on these systems in-situ to monitor the reduction species formed and the kinetics of their reduction. In-situ XANES clearly demonstrates that the formation of silver particles is severely impeded by the addition of copper and that the copper is converted from Cu(II) to Cu(I) during reduction and completely reverts back to Cu(II) during cooling. There are no indications at any stage of the formation of bimetallic Ag-Cu clusters. Interestingly, the Ag/Cu ratio appears to have no influence of the reduction kinetics and reduction products formed with only the highest Si/Al ratio (MR = 128) investigated during this study having an influence on the reduction and stability to air oxidation.

  7. Lithology, mineralogy, and paleontology of Quaternary lake deposits in Long Valley Caldera, California

    USGS Publications Warehouse

    Fournier, R.B.

    1989-01-01

    Drill cores and cuttings from two drill holes, about 3 km apart, in Long Valley caldera, Mono County, California, were studied using x-ray diffraction and optical methods. A thick sequence of tuffs and lake sediments was encountered in LVCH-1 (1,000 ft deep) and Republic well 66-29 (6,920 ft deep), drilled in the southeast part of the Long Valley caldera. Ostracods, diatoms, and isotopic data indicate that the sediments and tuffs were deposited in a shallow caldera lake which changed in salinity over time. Conditions ranged from very saline in the older lake to fresh in the youngest. The sequence of secondary minerals from top to bottom is: clinoptilolite, mordenite, analcime, K-feldspar (and albite). In some geothermal systems, this sequence of secondary minerals is a function of temperature; however, the paleontological and isotopic data indicate that the change in secondary minerals with increasing depth is due to the older strata being deposited in a more saline environment. No mineralogical evidence of hydrothermal alteration is present, although the high lithium content of some clays and feldspars and the isotopic composition of some sulfate (gypsum) seems to require a hydrothermal source. (Lantz-PTT)

  8. Specificity of sites within eight-membered ring zeolite channels for carbonylation of methyls to acetyls.

    PubMed

    Bhan, Aditya; Allian, Ayman D; Sunley, Glenn J; Law, David J; Iglesia, Enrique

    2007-04-25

    The acid-catalyzed formation of carbon-carbon bonds from C1 precursors via CO insertion into chemisorbed methyl groups occurs selectively within eight-membered ring (8-MR) zeolite channels. This elementary step controls catalytic carbonylation rates of dimethyl ether (DME) to methyl acetate. The number of O-H groups within 8-MR channels was measured by rigorous deconvolution of the infrared bands for O-H groups in cation-exchanged and acid forms of mordenite (M,H-MOR) and ferrierite (H-FER) after adsorption of basic probe molecules of varying size. DME carbonylation rates are proportional to the number of O-H groups within 8-MR channels. Na+ cations selectively replaced protons within 8-MR channels and led to a disproportionate decrease in carbonylation turnover rates (per total H+). These conclusions are consistent with the low or undetectable rates of carbonylation on zeolites without 8-MR channels (H-BEA, H-FAU, H-MFI). Such specificity of methyl reactivity upon confinement within small channels appears to be unprecedented in catalysis by microporous solids, which typically select reactions by size exclusion of bulkier transition states. PMID:17397162

  9. Xylose isomerization with zeolites in a two-step alcohol-water process.

    PubMed

    Paniagua, Marta; Saravanamurugan, Shunmugavel; Melian-Rodriguez, Mayra; Melero, Juan A; Riisager, Anders

    2015-03-01

    Isomerization of xylose to xylulose was efficiently catalyzed by large-pore zeolites in a two-step methanol-water process that enhanced the product yield significantly. The reaction pathway involves xylose isomerization to xylulose, which, in part, subsequently reacts with methanol to form methyl xyluloside (step 1) followed by hydrolysis after water addition to form additional xylulose (step 2). NMR spectroscopy studies performed with (13) C-labeled xylose confirmed the proposed reaction pathway. The most active catalyst examined was zeolite Y, which proved more active than zeolite beta, ZSM-5, and mordenite. The yield of xylulose obtained over H-USY (Si/Al=6) after 1 h of reaction at 100 °C was 39%. After water hydrolysis in the second reaction step, the yield increased to 47%. Results obtained from pyridine adsorption studies confirm that H-USY (6) is a catalyst that combines Brønsted and Lewis acid sites, and isomerizes xylose in alcohol media to form xylulose at low temperature. The applied zeolites are commercially available; do not contain any auxiliary tetravalent metals, for example, tin, titanium, or zirconium; isomerize xylose efficiently; are easy to regenerate; and are prone to recycling. PMID:25703506

  10. Surface-Energetic Heterogeneity of Nanoporous Solids for CO2 and CO Adsorption: The Key to an Adsorption Capacity and Selectivity at Low Pressures.

    PubMed

    Kim, Moon Hyeon; Cho, Il Hum; Choi, Sang Ok; Lee, In Soo

    2016-05-01

    This study has been focused on surface energetic heterogeneity of zeolite (H-mordenite, "HM"), activated carbon ("RB2") and metal-organic framework family ("Z1200") materials and their isotherm features in adsorption of CO2 and CO at 25 degrees C and low pressures ≤ 850 Torr. The nanoporous solids showed not only distinctive shape of adsorption isotherms for CO2 with relatively high polarizability and quadrupole moment but also different capacities in the CO2 adsorption. These differences between the adsorbents could be well correlated with their surface nonuniformity. The most heterogeneous surfaces were found with the HM that gave the highest CO2 uptake at all pressures allowed, while the Z1200 consisted of completely homogeneous surfaces and even CO2 adsorption linearly increased with pressure. An intermediate character was indicated on the surface of RB2 and thus this sorbent possessed isotherm features between the HM and Z1200 in CO2 adsorption. Such different surface energetics was fairly consistent with changes in CO2/CO selectivity on the nanoporous adsorbents up to equilibrated pressures near 850 Torr. PMID:27483776

  11. Adsorption and photocatalytic degradation of pharmaceuticals and pesticides by carbon doped-TiO2 coated on zeolites under solar light irradiation.

    PubMed

    An, Ye; de Ridder, David Johannes; Zhao, Chun; Schoutteten, Klaas; Bussche, Julie Vanden; Zheng, Huaili; Chen, Gang; Vanhaecke, Lynn

    2016-01-01

    To evaluate the performance of zeolite-supported carbon-doped TiO(2) composite catalysts toward target pollutants under solar light irradiation, the adsorption and photocatalytic degradation of 18 pharmaceuticals and pesticides with distinguishing features (molecular size and volume, and photolysis) were investigated using mordenite zeolites with SiO(2)/Al(2)O(3) ratios of 18 and 240. Different quantities of carbon-doped TiO(2) were coated on the zeolites, and then the finished composite catalysts were tested in demineralized, surface, and hospital wastewater samples, respectively. The composite photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, and surface area and porosity analyses. Results showed that a dispersed layer of carbon-doped TiO(2) is formed on the zeolite surface; this layer blocks the micropores of zeolites and reduces their surface area. However, these reductions did not significantly affect adsorption onto the zeolites. Our results demonstrated that zeolite-supported carbon-doped TiO(2) systems can effectively degrade 18 pharmaceuticals and pesticides in demineralized water under natural and simulated solar light irradiation. In surface and hospital wastewaters, zeolite-supported carbon-doped TiO(2) systems present excellent anti-interference capability against radical scavengers and competitive organics for pollutants removal, and higher pollutants adsorption on zeolites evidently enhances the removal rate of target pollutants in surface and hospital wastewater samples with a complicated matrix. PMID:27332831

  12. Biomass-derived chemicals: synthesis of biodegradable surfactant ether molecules from hydroxymethylfurfural.

    PubMed

    Arias, Karen S; Climent, Maria J; Corma, Avelino; Iborra, Sara

    2014-01-01

    A new class of biodegradable anionic surfactants with structures based on 5-alkoxymethylfuroate was prepared starting from 5-hydroxymethylfurfural (HMF), through a one-pot-two-steps process which involves the selective etherification of HMF with fatty alcohols using heterogeneous solid acid, followed by a highly selective oxidation of the formyl group with a gold catalyst. The etherification step was optimized using aluminosilicates as acid catalysts with different pore topologies (H-Beta, HY, Mordenite, ZSM-5, ITQ-2, and MCM-41), different active sites (Bronsted or Lewis) and different adsorption properties. It was shown that highly hydrophobic defect-free H-Beta zeolites with Si/Al ratios higher than 25 are excellent acid catalysts to perform the selective etherification of HMF with fatty alcohols, avoiding the competitive self-etherification of HMF. Moreover, the 5-alkoxymethylfurfural derivatives obtained can be selectively oxidized to the corresponding furoic salts in excellent yield using Au/CeO2 as catalyst and air as oxidant, at moderated temperatures. Both H-Beta zeolite and Au/CeO2 could be reused several times without loss of activity. PMID:24106062

  13. Savannah River Laboratory monthly report

    SciTech Connect

    Not Available

    1986-02-01

    Brief summaries are given in the areas of defense waste and laboratory operations, nuclear reactors and scientific computation, and chemical processes and environmental technology. The performance of waste glass samples has been tested. A prototype Pu-238 waste incinerator is being tested. A monitor system is being developed to allow unattended computer system operation. A program to review and update the Reactor Technical Standards and Specifications is in progress. Analysis of a medium LOCA in a reactor D/sub 2/O coolant system is reported. Preliminary results are given for alternative degreasers. Modernization of a JOSHUA computer system is reported. The safety of a fuel tube fabrication building is discussed. The program to evaluate reactor materials is summarized. A design has been developed for a silver-mordenite packed bed reactor to remove radioactive iodine from uranium fuel dissolver off-gas. Automated online analyzers were developed. Ground-penetrating radar has been evaluated. The safety of two space probes powered by plutonium dioxide thermal generators was evaluated. (LEW)

  14. Novel Sorbent Development and Evaluation for the Capture of Krypton and Xenon from Nuclear Fuel Reprocessing Off-Gas Streams

    SciTech Connect

    Troy G. Garn; Mitchell R. Greenhalgh; Jack D. Law

    2013-10-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, INL sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up.

  15. Novel Sorbent Development and Evaluation for the Capture of Krypton and Xenon from Nuclear Fuel Reprocessing Off-Gas Streams

    SciTech Connect

    Troy G. Garn; Mitchell R. Greenhalgh; Jack D. Law

    2013-09-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, INL sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up.

  16. Novel sorbent development and evaluation for the capture of krypton and xenon from nuclear fuel reprocessing off-gas stream

    SciTech Connect

    Garn, T.G.; Greenhalgh, M.R.; Law, J.D.

    2013-07-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, Idaho National Laboratory sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up. (authors)

  17. Petrology and hydrothermal mineralogy of U. S. Geological Survey Newberry 2 drill core from Newberry caldera, Oregon

    SciTech Connect

    Keith, T.E.C.; Bargar, K.E.

    1988-09-10

    U.S. Geological Survey Newberry 2 was drilled to a depth of 932 m within Newberry caldera. The bottom-hole temperature of 265/sup 0/C is the highest reported temperature of any drill hole in the Cascades region of the United States. The upper part of the stratigraphic section pentrated by Newberry 2 consists of caldera fill below which are increasingly more mafic lavas ranging from rhyodacite at 501 m to basalt at 932 m. Measured temperatures shallower than 300 m are less than 35/sup 0/C, and rock alteration consists of hydration of glass and local palagonitization of basaltic tuffs. Incipient zeolitization and partial smectite replacement of ash and pumice occurred throughout the pumiceous lithic tuffs from 300 to 500 m. Higher-temperature alteration of the tuffs to chlorite and mordenite occurs adjacent to a rhyodacite sill at 460--470 m; alteration minerals within the sill consist of pyrrhotite, pyrite, quartz, calcite, and siderite. Below 697 m the rocks are progressively more altered with depth mainly because of increased temperature along a conductive gradient from 100/sup 0/C at 697 m to 265/sup 0/C at 930 m. Fluid inclusions in quartz and calcite indicate that temperature in the past have been higher than at present, most likely due to local confining pressures between impermeable lava flows.

  18. Evaluation of dust-related health hazards associated with air coring at G-Tunnel, Nevada Test Site

    SciTech Connect

    Skaggs, B.J.; Ortiz, L.W.; Burton, D.J.; Isom, B.L.; Vigil, E.A.

    1991-03-01

    The Yucca Mountain Project was established to evaluate the potential for storing high-level radioactive wastes in geologic formations. Hydrologists recommended that drilling or coring in support of characterization tests be performed dry. Dry drilling, or air coring, presents a concern about health protection for the drilling personnel. The rock generally has a high silica content, and natural zeolites are abundant. Some zeolites are fibrous, leading to concerns that inhalation may result in asbestos-like lung diseases. An industrial hygiene study (IH) was conducted as part of an air coring technical feasibility test. The IH study found the potential for exposures to airborne silica and nuisance dusts to be within regulatory requirements and determined the commercial dust control equipment monitored to be effective when used in conjunction with a good area ventilation system and sound IH practices. Fibrous zeolites were not detected. Recommendations for the Yucca Mountain studies are (1) dust collection and control equipment equivalent or superior to that monitored must be used for any dry drilling activity and must be used with good general dilution ventilation and local exhaust ventilation provided on major emission sources; (2) good industrial hygiene work practices must be implemented, including monitoring any area where zeolitic fibers are suspect; and (3) a study should be conducted to determine the biological effects of the fibrous zeolite, mordenite. 25 refs., 17 figs., 14 tabs.

  19. Low sintering temperature glass waste forms for sequestering radioactive iodine

    DOEpatents

    Nenoff, Tina M.; Krumhansl, James L.; Garino, Terry J.; Ockwig, Nathan W.

    2012-09-11

    Materials and methods of making low-sintering-temperature glass waste forms that sequester radioactive iodine in a strong and durable structure. First, the iodine is captured by an adsorbant, which forms an iodine-loaded material, e.g., AgI, AgI-zeolite, AgI-mordenite, Ag-silica aerogel, ZnI.sub.2, CuI, or Bi.sub.5O.sub.7I. Next, particles of the iodine-loaded material are mixed with powdered frits of low-sintering-temperature glasses (comprising various oxides of Si, B, Bi, Pb, and Zn), and then sintered at a relatively low temperature, ranging from 425.degree. C. to 550.degree. C. The sintering converts the mixed powders into a solid block of a glassy waste form, having low iodine leaching rates. The vitrified glassy waste form can contain as much as 60 wt % AgI. A preferred glass, having a sintering temperature of 500.degree. C. (below the silver iodide sublimation temperature of 500.degree. C.) was identified that contains oxides of boron, bismuth, and zinc, while containing essentially no lead or silicon.

  20. Removal efficiency of water purifier and adsorbent for iodine, cesium, strontium, barium and zirconium in drinking water.

    PubMed

    Sato, Itaru; Kudo, Hiroaki; Tsuda, Shuji

    2011-01-01

    The severe incident of Fukushima Daiichi Nuclear Power Station has caused radioactive contamination of environment including drinking water. Radioactive iodine, cesium, strontium, barium and zirconium are hazardous fission products because of the high yield and/or relatively long half-life. In the present study, 4 pot-type water purifiers and several adsorbents were examined for the removal effects on these elements from drinking water. Iodide, iodate, cesium and barium were removed by all water purifiers with efficiencies about 85%, 40%, 75-90% and higher than 85%, respectively. These efficiencies lasted for 200 l, which is near the recommended limits for use of filter cartridges, without decay. Strontium was removed with initial efficiencies from 70% to 100%, but the efficiencies were slightly decreased by use. Zirconium was removed by two models, but hardly removed by the other models. Synthetic zeolite A4 efficiently removed cesium, strontium and barium, but had no effect on iodine and zirconium. Natural zeolite, mordenite, removed cesium with an efficiency as high as zeolite A4, but the removal efficiencies for strontium and barium were far less than those of zeolite A4. Activated carbon had little removal effects on these elements. In case of radioactive contamination of tap water, water purifiers may be available for convenient decontamination of drinking water in the home. PMID:22129747

  1. Association of Indigo with Zeolites for Improved Color Stabilization

    NASA Astrophysics Data System (ADS)

    Dejoie, Catherine; Martinetto, Pauline; Dooryhée, Eric; van Elslande, Elsa; Blanc, Sylvie; Bordat, Patrice; Brown, Ross; Porcher, Florence; Anne, Michel

    2010-10-01

    The durability of an organic colour and its resistance against external chemical agents and exposure to light can be significantly enhanced by hybridizing the natural dye with a mineral. In search for stable natural pigments, the present work focuses on the association of indigo blue with several zeolitic matrices (LTA zeolite, mordenite, MFI zeolite). The manufacturing of the hybrid pigment is tested under varying oxidising conditions, using Raman and UV-visible spectrometric techniques. Blending indigo with MFI is shown to yield the most stable composite in all of our artificial indigo pigments. In absence of defects and substituted cations such as aluminum in the framework of the MFI zeolite matrix, we show that matching the pore size with the dimensions of the guest indigo molecule is the key factor. The evidence for the high colour stability of indigo@MFI opens a new path for modeling the stability of indigo in various alumino-silicate substrates such as in the historical Maya Blue pigment.

  2. Probing the structure of complex solids using a distributed computing approach-Applications in zeolite science

    SciTech Connect

    French, Samuel A.; Coates, Rosie; Lewis, Dewi W.; Catlow, C. Richard A.

    2011-06-15

    We demonstrate the viability of distributed computing techniques employing idle desktop computers in investigating complex structural problems in solids. Through the use of a combined Monte Carlo and energy minimisation method, we show how a large parameter space can be effectively scanned. By controlling the generation and running of different configurations through a database engine, we are able to not only analyse the data 'on the fly' but also direct the running of jobs and the algorithms for generating further structures. As an exemplar case, we probe the distribution of Al and extra-framework cations in the structure of the zeolite Mordenite. We compare our computed unit cells with experiment and find that whilst there is excellent correlation between computed and experimentally derived unit cell volumes, cation positioning and short-range Al ordering (i.e. near neighbour environment), there remains some discrepancy in the distribution of Al throughout the framework. We also show that stability-structure correlations only become apparent once a sufficiently large sample is used. - Graphical Abstract: Aluminium distributions in zeolites are determined using e-science methods. Highlights: > Use of e-science methods to search configurationally space. > Automated control of space searching. > Identify key structural features conveying stability. > Improved correlation of computed structures with experimental data.

  3. Removal of water and iodine by solid sorbents: adsorption isotherms and kinetics

    SciTech Connect

    Lin, R.; Tavlarides, L.L.

    2013-07-01

    Tritium and iodine-129 are two major radioactive elements that are present in off-gases from spent fuel reprocessing plants. Adsorption by solid sorbents is the state-of-the-art technique for removal of these species from off-gases. Modeling and simulating adsorption processes require accurate adsorption equilibrium and kinetic data to permit reasonable estimates of process parameters. We have developed a continuous flow single-pellet adsorption system to gather accurate adsorption equilibrium and kinetic data for adsorption of water by molecular sieve 3A and for adsorption of iodine by silver exchanged mordenite. In this paper, the design of the water and iodine adsorption experimental systems are briefly described and results of water adsorption experiments are presented and discussed. Water uptake curves are fitted with the linear-driving force (LDF) model and the shrinking-core model to determine kinetic parameters. It is shown that the kinetics of water adsorption on zeolite 3A under current experimental conditions is controlled by both the external film resistance and the macro-pore diffusion and can be predicted by both the LDF model and the shrinking-core model with the former one performing slightly better. Preliminary results from iodine adsorption experiments will be presented in the conference.

  4. Initial Effects of NOx on Idodine and Methyl Iodine Loading of AgZ and Aerogels

    SciTech Connect

    Bruffey, Stephanie H.; Jubin, Robert Thomas

    2015-03-31

    This initial evaluation provides insight into the effect of NO on the adsorption of both I2 and CH3I onto reduced silver-exchanged mordenite (Ag0Z). It was determined that adsorption of CH3I onto Ag0Z occurs at approximately 50% of the rate of I2 adsorption onto Ag0Z, although total iodine capacities are comparable. Addition of 1% NO to the simulated off-gas stream results in very similar loading behaviors and iodine capacities for both iodine species. This is most likely an effect of CH3I oxidation to I2 by NO prior to contact with the sorbent bed. Completion of tests including NO2 in the simulated off-gas stream was delayed due to vendor NO2 production schedules. A statistically designed test matrix is partially completed, and upon conclusion of the suggested experiments, the effects of temperature, NO, NO2, and water vapor on the sorption of CH3I and I2 onto Ag0Z will be able to be statistically resolved. This work represents progress towards that aim.

  5. Determine Minimum Silver Flake Addition to GCM for Iodine Loaded AgZ

    SciTech Connect

    Garino, Terry J.; Nenoff, Tina M.; Rodriguez, Mark A.

    2014-04-01

    The minimum amount of silver flake required to prevent loss of I{sub 2} during sintering in air for a SNL Glass Composite Material (GCM) Waste Form containing AgI-MOR (ORNL, 8.7 wt%) was determined to be 1.1 wt% Ag. The final GCM composition prior to sintering was 20 wt% AgI-MOR, 1.1 wt% Ag, and 80 wt% Bi-Si oxide glass. The amount of silver flake needed to suppress iodine loss was determined using thermo gravimetric analysis with mass spectroscopic off-gas analysis. These studies found that the ratio of silver to AgI-MOR required is lower in the presence of the glass than without it. Therefore an additional benefit of the GCM is that it serves to inhibit some iodine loss during processing. Alternatively, heating the AgI-MOR in inert atmosphere instead of air allowed for densified GCM formation without I{sub 2} loss, and no necessity for the addition of Ag. The cause of this behavior is found to be related to the oxidation of the metallic Ag to Ag{sup +} when heated to above ~300{degrees}C in air. Heating rate, iodine loading levels and atmosphere are the important variables that determine AgI migration and results suggest that AgI may be completely incorporated into the mordenite structure by the 550{degrees}C sintering temperature.

  6. Radionuclide Leaching from Organic Ion Exchange Resin

    SciTech Connect

    Delegard, C.H.; Rinehart, D.E.

    1999-04-02

    Laboratory tests were performed to examine the efficacy of leach treatments for decontaminating organic ion exchange resins (OIER), which have been found in a number of samples retrieved from K East Basin sludge. Based on process records, the OIER found in the K Basins is a mixed-bet strong acid/strong base material marketed as Purolite{trademark} NRW-037. Radionuclides sorbed or associated with the OIER can restrict its disposal to the Environmental Restoration Disposal Facility (ERDF). The need for testing to support development of a treatment process for K Basin sludge has been described in Section 4.2 of ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process'' (Flament 1998). To help understand the effects of anticipated OIER elutriation and washing, tests were performed with well-rinsed OIER material from K East Basin floor sludge (sample H-08 BEAD G) and with well-rinsed OIER having approximately 5% added K East canister composite sludge (sample KECOMP). The rinsed resin-bearing material also contained the inorganic ion exchanger Zeolon-900{trademark}, a zeolite primarily composed of the mineral mordenite. The zeolite was estimated to comprise 27 weight percent of the dry H-08 BEAD G material.

  7. Design and cost estimate for the SRL integrated hot off gas facility using selective adsorption

    SciTech Connect

    Pence, D T; Kirstein, B E

    1981-07-01

    Based on the results of an engineering-scale demonstration program, a design and cost estimate were performed for a 25-m/sup 3//h (15-ft/sup 3//min) capacity pilot plant demonstration system using selective adsorption technology for installation at the Integrated Hot Off Gas Facility at the Savannah River Plant. The design includes provisions for the destruction of NO/sub x/ and the concentration and removal of radioisotopes of ruthenium, iodine-129, tritiated water vapor, carbon-14 contaminated carbon dioxide, and krypton-85. The nobel gases are separated by the use of selective adsorption on mordenite-type zeolites. The theory of noble gas adsorption on zeolites is essentially the same as that for the adsorption of noble gases on activated charcoals. Considerable detail is provided regarding the application of the theory to adsorbent bed designs and operation. The design is based on a comprehensive material balance and appropriate heat transfer calculations. Details are provided on techniques and procedures used for heating, cooling, and desorbing the adsorbent columns. Analyses are also given regarding component and arrangement selection and includes discussions on alternative arrangements. The estimated equipment costs for the described treatment system is about $1,400,000. The cost estimate includes a detailed equipment list of all the major component items in the design. Related technical issues and estimated system performance are also discussed.

  8. Kinetics of silica-phase transitions

    SciTech Connect

    Duffy, C.J.

    1993-07-01

    In addition to the stable silica polymorph quartz, several metastable silica phases are present in Yucca Mountain. The conversion of these phases to quartz is accompanied by volume reduction and a decrease in the aqueous silica activity, which may destabilize clinoptilolite and mordenite. The primary reaction sequence for the silica phases is from opal or glass to disordered opal-CT, followed by ordering of the opal-CT and finally by the crystallization of quartz. The ordering of opal-CT takes place in the solid state, whereas the conversion of opal-CT takes place through dissolution-reprecipitation involving the aqueous phase. It is proposed that the rate of conversion of opal-CT to quartz is controlled by diffusion of defects out of a disordered surface layer formed on the crystallizing quartz. The reaction rates are observed to be dependent on temperature, pressure, degree of supersaturation, and pH. Rate equations selected from the literature appear to be consistent with observations at Yucca Mountain.

  9. EU-12: A Small-Pore, High-Silica Zeolite Containing Sinusoidal Eight-Ring Channels.

    PubMed

    Bae, Juna; Cho, Jung; Lee, Jeong Hwan; Seo, Sung Man; Hong, Suk Bong

    2016-06-20

    Zeolite EU-12, the framework structure of which has remained unsolved during the past 30 years, is synthesized at a specific SiO2 /Al2 O3 ratio using choline as an organic structure-directing agent, with both Na(+) and Rb(+) ions present. Synchrotron powder X-ray diffraction and Rietveld analyses reveal that the EU-12 structure has a two-dimensional 8-ring channel system. Among the two distinct 8-ring (4.6×2.8 and 5.0×2.7 Å) channels along c axis, the smaller one interconnects with the sinusoidal 8-ring (4.8×3.3 Å) channel along a axis. The other large one is simply linked up with the sinusoidal channel by sharing 8-rings (4.8×2.6 Å) in the ac plane. The proton form of EU-12 was found to show a considerably higher ethene selectivity in the low-temperature dehydration of ethanol than H-mordenite, the best catalyst for this reaction. PMID:27174769

  10. Ion exchange in a zeolite-molten chloride system

    SciTech Connect

    Woodman, R.H.; Pereira, C.

    1997-07-01

    Electrometallurgical treatment of spent nuclear fuel results in a secondary waste stream of radioactive fission products dissolved in chloride salt. Disposal plans include a waste form that can incorporate chloride forms featuring one or more zeolites consolidated with sintered glass. A candidate method for incorporating fission products in the zeolites is passing the contaminated salt over a zeolite column for ion exchange. To date, the molten chloride ion-exchange properties of four zeolites have been investigated for this process: zeolite A, IE95{reg_sign}, clinoptilolite, and mordenite. Of these, zeolite A has been the most promising. Treating zeolite 4A, the sodium form of zeolite A , with the solvent salt for the waste stream-lithium-potassium chloride of eutectic melting composition, is expected to provide a material with favorable ion-exchange properties for the treatment of the waste salt. The authors constructed a pilot-plant system for the ion-exchange column. Initial results indicate that there is a direct relationship between the two operating variable of interest, temperature, and initial sodium concentration. Also, the mass ratio has been about 3--5 to bring the sodium concentration of the effluent below 1 mol%.

  11. Petrology, sedimentology, and diagenesis of hemipelagic limestone and tuffaceous turbidities in the Aksitero Formation, central Luzon, Philippines

    USGS Publications Warehouse

    Garrison, Robert E.; Espiritu, E.; Horan, L.J.; Mack, L.E.

    1979-01-01

    The Aksitero Formation of central Luzon is an upper Eocene and lower Oligocene sequence of evenly bedded hemipelagic limestone with a few thin interlayers of tuffaceous turbidites. The limestone consists chiefly of planktonic foraminifers and calcareous nannofossils, with up to 30 percent of noncarbonate components, chiefly volcaniclastic debris. The tuff layers are graded beds. Composed mainly of glass shards, pumice fragments, crystals, and fine-grained volcanic rock fragments. Hydrocarbons migrated into the pores of the tuffaceous layers early during diagenesis but they were subsequently flushed out and only bitumen remains, chiefly as thin coatings on grains and wthin pumice vesicles. Later during diagenesis, zeolites (mordenite and c1inoptilolite) and secondary calcite preferentially replaced glass shards and pumice fragments. Deposition of the Aksitero Formation probably occurred at depths of at least 1,000 meters within a subsiding basin adjacent to an active island arc system. Submarine ash eruptions of silicic composition caused volcaniclastic turbidity currents that occasionally reached the basin floor. The more proximal facies of these volcaniclastic deposits may be prospective for hydrocarbons.

  12. Comparison between leached metakaolin and leached diatomaceous earth as raw materials for the synthesis of ZSM-5.

    PubMed

    Aguilar-Mamani, Wilson; García, Gustavo; Hedlund, Jonas; Mouzon, Johanne

    2014-01-01

    Inexpensive raw materials have been used to prepare ZSM-5 zeolites with SiO2/Al2O3 molar ratios in the range 20 - 40. Kaolin or Bolivian diatomaceous earth was used as aluminosilicate raw materials and sodium hydroxide and n-butylamine were used as mineralizing agents and template. Dealumination of the raw materials by acid leaching made it possible to reach appropriate SiO2/Al2O3 ratios and to reduce the amount of iron and other impurities. After mixing the components and aging, hydrothermal treatment was carried out and the products were recovered The results clearly show for the first time that well-crystallized ZSM-5 can be directly prepared from leached metakaolin or leached diatomaceous earth using sodium hydroxide and n-butylamine as mineralizing agents and template under appropriate synthesis conditions. A longer induction time prior to crystallization was observed for reaction mixtures prepared from leached diatomaceous earth, probably due to slower digestion of the fossilized diatom skeletons as compared with that for microporous leached metakaolin. The use of leached diatomaceous earth allowed higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of Mordenite formed, which was related to the high calcium content of diatomaceous earth. Another considerable advantage of diatomaceous earth over kaolin is that diatomaceous earth does not require heat treatment at high temperature for metakaolinization. PMID:25019042

  13. Reaction-path calculations of groundwater chemistry and mineral formation at Rainier Mesa, Nevada

    SciTech Connect

    Kerrisk, J F

    1983-12-01

    Reaction-patch calculations of groundwater chemistry and mineral formation at Rainier Mesa, Nevada, have been done using a model of volcanic-glass dissolution by water that is initially saturated with CO{sub 2}. In the reaction-path calculation, rate processes control the availability of species through dissolution of volcanic glass, and equilibrium processes distribute the species between the aqueous phase and mineral phases in equilibrium at each step in the reaction path. The EQ3/6 chemical-equilibrium programs were used for the calculation. Formation constants were estimated for three zeolites (clinoptilolite, mordenite, and heulandite), so they could be considered as possible mineral precipitates. The first stage of mineral evolution, from volcanic glass to a cristobalite, smectite clay, and zeolite mixture, was modeled quite well. Predicted aqueous-phase compositions and precipitates agree with observations at Rainier Mesa and other Nevada Test Site areas. Further mineral evolution, to quartz, clay, analcime, and albite mixtures, was also modeled. Decreasing aqueous silica activity from the first stage, where cristobalite precipitates, to later stages, where quartz is present, was the controlling variable in the mineral evolution. 30 references, 20 figures, 4 tables.

  14. Aging and iodine loading of silver-functionalized aerogels

    SciTech Connect

    Bruffey, S.H.; Jubin, R.T.; Anderson, K.K.; Walker, J.F.

    2013-07-01

    Engineered silver-functionalized silica aerogels are being investigated for their potential application in off-gas treatment at a used nuclear fuel reprocessing facility. Reprocessing will release several key volatile radionuclides, including iodine-129. To achieve regulatory compliance, iodine-129 must be removed from any off-gas stream prior to environmental discharge. Ag{sup 0}-functionalized aerogels have been demonstrated to have high iodine-capture capacity, high porosity, and potential for conversion into a waste form. Capture materials used in off-gas treatment may be exposed to a heated, high-humidity, acidic gas stream for months. Extended exposure to this stream could affect sorbent performance. It was the aim of this study to evaluate what impacts might be observed when Ag{sup 0}-functionalized aerogels prepared at Pacific Northwest National Laboratory were contacted with a dry air stream for up to 6 months and then used to adsorb iodine from a synthetic off-gas stream. Results demonstrate that there is some loss of iodine-capture capacity caused by aging, but that this loss is not as marked as for aging of more traditional iodine sorbents, such as silver-impregnated mordenite. Specifically, aging silver-functionalized aerogel under a dry air stream for up to 6 months can decrease its iodine capacity from 41 wt% to 32 wt%. (authors)

  15. AGING AND IODINE LOADING OF SILVER-FUNCTIONALIZED AEROGELS

    SciTech Connect

    Bruffey, Stephanie H; Jubin, Robert Thomas; Anderson, Kaara K; Walker Jr, Joseph Franklin

    2013-01-01

    Engineered silver-functionalized silica aerogels are being investigated for their application in off-gas treatment at a used nuclear fuel reprocessing facility. Reprocessing will release several key volatile radionuclides, including iodine-129. To achieve regulatory compliance, iodine-129 must be removed from any off-gas stream prior to environmental discharge. Silver-functionalized aerogels have been demonstrated to have high iodine capture capacity, high porosity and potential for conversion into a waste form. Capture materials used in off-gas treatment may be exposed to a heated, high humidity, acidic gas stream for months. Extended exposure to this stream could affect sorbent performance. It was the aim of this study to evaluate what impacts might be observed when Ag0-functionalized aerogels prepared at Pacific Northwest National Laboratory were contacted with a dry air stream for up to 6 months and then used to adsorb iodine from a synthetic off-gas stream. Results demonstrate that there is some loss of iodine capture capacity caused by aging, but that this loss is not as marked as for aging of more traditional iodine sorbents, such as silver-impregnated mordenite. Specifically, aging silver-functionalized aerogel under a dry air stream for up to 6 months can decrease its iodine capacity from 41wt% to 32wt%.

  16. Status of radioiodine control for nuclear fuel reprocessing plants

    SciTech Connect

    Burger, L.L.; Scheele, R.D.

    1983-07-01

    This report summarizes the status of radioiodine control in a nuclear fuel reprocessing plant with respect to capture, fixation, and disposal. Where possible, we refer the reader to a number of survey documents which have been published in the last four years. We provide updates where necessary. Also discussed are factors which must be considered in developing criteria for iodine control. For capture from gas streams, silver mordenite and a silver nitrate impregnated silica (AC-6120) are considered state-of-the-art and are recommended. Three aqueous scrubbing processes have been demonstrated: Caustic scrubbing is simple but probably will not give an adequate iodine retention by itself. Mercurex (mercuric nitrate-nitric acid scrubbing) has a number of disadvantages including the use of toxic mercury. Iodox (hyperazeotropic nitric acid scrubbing) is effective but employs a very corrosive and hazardous material. Other technologies have been tested but require extensive development. The waste forms recommended for long-term storage or disposal are silver iodide, the iodates of barium, strontium, or calcium, and silver loaded sorbents, all fixed in cement. Copper iodide in bitumen (asphalt) is a possibility but requires testing. The selection of a specific form will be influenced by the capture process used.

  17. Determination of Si/Al molar ratios in microporous zeolites using calibration-free laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Horňáčková, M.; Horňáček, M.; Rakovský, J.; Hudec, P.; Veis, P.

    2013-10-01

    In this paper, the potential application of a calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method for the determination of the silicon-to-aluminum molar ratio in microporous zeolites (with both intermediate and high silica contents) is discussed. Three different zeolite types, i.e., mordenite and zeolites type Y and ZSM-5, were analyzed in this study and were shown to have Si/Al molar ratios in the range between 2.3 and 51.8. Many ionic and neutral atomic spectral lines of silicon and aluminum were detected in the measured LIBS spectra in the spectral range 200-1000 nm, but not all of the observed spectral lines are convenient for a CF-LIBS analysis. To increase the accuracy of the results, only lines with no or low self-absorption probability were selected. A systematic method is proposed to select spectral lines based on three main parameters: the transition probability (Einstein coefficient), the lower level energy of the observed transition and the number density ratio between singly ionized and neutral species (as calculated for Si and Al for the measured electron density and electron temperature). The calculated Si/Al molar ratios were close to that determined by wet chemical analysis with an average relative standard deviation of approximately 5% (maximum less than 15%). Our results point to the possibility of using CF-LIBS for analysis of these types of materials and for determination of Si/Al molar ratios.

  18. AGATE as an indicator of impact structures: an example from Saaksjarvi, Finland

    NASA Astrophysics Data System (ADS)

    Kinnunen, Kari A.; Lindqvist, Kristian

    1998-01-01

    Mineralogical, petrographical and chemical determinations were made for 743 agate (banded variety of chalcedonic quartz) nodules (diameters from 5 mm to 5 cm) formed during post-impact, low-temperature hydrothermal activity as vesicle fillings in the melt rocks of the Saaksjarvi meteorite impact structure (diameter 5 km) in SW-Finland. Other hydrothermal vesicle fillings in the impact melt rocks include chlorite, mordenite, smectite and kaolinite. The agates were classified into two types, whose mineralogical properties and chemical compositions fall within the range of volcanic agates (basaltic and rhyolitic host rocks). The relatively high age (about 510 Ma) of the Saaksjarvi impact melt rocks, however, is reflected by the presence of recrystallization textures, which are rare in younger volcanic agates. The Saaksjarvi structure was initially located after following the fortuitous discovery of agate "path-finders" in the glacial overburden. It is recommended that wherever volcanic type agates are found as float in Precambrian shield areas devoid of younger volcanic rocks, the possible presence of impact (or volcanic) craters in the vicinity should be considered.

  19. Gold nanoparticles as efficient antimicrobial agents for Escherichia coli and Salmonella typhi

    PubMed Central

    2013-01-01

    Background It is imperative to eliminate bacteria present in water in order to avoid problems in healthy. Escherichia coli and Salmonella typhi bacteria are two common pollutants and they are developing resistance to some of the most used bactericide. Therefore new biocide materials are being tested. Thus, gold nanoparticles are proposed to inhibit the growth of these two microorganisms. Results Gold nanoparticles were supported onto clinoptilolite, mordenite and faujasite zeolites. Content of gold in materials varied between 2.3 and 2.8 wt%. The size, dispersion and roughness of gold nanoparticles were highly dependent of the zeolite support. The faujasite support was the support where the 5 nm nanoparticles were highly dispersed. The efficiency of gold-zeolites as bactericides of Escherichia coli and Salmonella typhi was determined by the zeolite support. Conclusions Gold nanoparticles dispersed on zeolites eliminate Escherichia coli and Salmonella typhi at short times. The biocidal properties of gold nanoparticles are influenced by the type of support which, indeed, drives key parameters as the size and roughness of nanoparticles. The more actives materials were pointed out Au-faujasite. These materials contained particles sized 5 nm at surface and eliminate 90–95% of Escherichia coli and Salmonella typhi colonies. PMID:23331621

  20. Thermodynamic modeling of natural zeolite stability

    SciTech Connect

    Chipera, S.J.; Bish, D.L.

    1997-06-01

    Zeolites occur in a variety of geologic environments and are used in numerous agricultural, commercial, and environmental applications. It is desirable to understand their stability both to predict future stability and to evaluate the geochemical conditions resulting in their formation. The use of estimated thermodynamic data for measured zeolite compositions allows thermodynamic modeling of stability relationships among zeolites in different geologic environments (diagenetic, saline and alkaline lakes, acid rock hydrothermal, basic rock, deep sea sediments). This modeling shows that the relative cation abundances in both the aqueous and solid phases, the aqueous silica activity, and temperature are important factors in determining the stable zeolite species. Siliceous zeolites (e.g., clinoptilolite, mordenite, erionite) present in saline and alkaline lakes or diagenetic deposits formed at elevated silica activities. Aluminous zeolites (e.g., natrolite, mesolite/scolecite, thomsonite) formed in basic rocks in association with reduced silica activities. Likewise, phillipsite formation is favored by reduced aqueous silica activities. The presence of erionite, chabazite, and phillipsite are indicative of environments with elevated potassium concentrations. Elevated temperature, calcic water conditions, and reduced silica activity help to enhance the laumontite and wairakite stability fields. Analcime stability increases with increased temperature and aqueous Na concentration, and/or with decreased silica activity.

  1. Growth of Megaspherulites In a Rhyolitic Vitrophyre

    NASA Technical Reports Server (NTRS)

    Smith, Robert K.; Tremallo, Robin L.; Lofgren, Gary E.

    2000-01-01

    Megaspherulites occur in the middle zone of a thick sequence of rhyolitic vitrophyre that occupies a small, late Eocene to early Oligocene volcanic-tectonic basin near Silver Cliff, Custer County, Colorado. Diameters of the megaspherulites range from 0.3 m to over 3.66 m, including a clay envelope. The megaspherulites are compound spherulites. consisting of an extremely large number (3.8 x 10(exp 9) to 9.9 x 10(exp 9)) of individual growth cones averaging 3 mm long by 1.25 mm wide at their termination. They are holocrystalline, very fine- to fine-grained, composed of disordered to ordered sanidine (orthoclase) and quartz, and surrounded by a thin K-feldspar, quartz rich rind, an inner clay layer with mordenite, and an outer clay layer composed wholly of 15 A montmorillonite. Whole rock analyses of the megaspherulites show a restricted composition from their core to their outer edge, with an average analyses of 76.3% SiO2, 0.34% CaO, 2.17% Na2O, 6.92% K2O, 0.83% H2O+ compared to the rhyolitic vitrophyre from which they crystallize with 71.07% SiO2, 0.57% CaO, 4.06% Na2O,4.l0% K2O, and 6.40% H2O+. The remaining oxides of Fe2O3 (total Fe), A12O3, MnO,MgO, TiO2, P2O5, Cr2O3, and trace elements show uniform distribution between the megaspherulites and the rhyolitic vitrophyre. Megaspherulite crystallization began soon after the rhyolitic lava ceased to flow as the result of sparse heterogeneous nucleation, under nonequilibrium conditions, due to a high degree of undercooling, delta T. The crystals grow with a fibrous habit which is favored by a large delta T ranging between 245 C and 295 C, despite lowered viscosity, and enhanced diffusion due to the high H2O content, ranging between 5% and 7%. Therefore, megaspherulite growth proceeded in a diffusion controlled manner, where the diffusion, rate lags behind the crystal growth rate at the crystal-liquid interface, restricting fibril lengths and diameters to the 10 micron to 15 micron and 3 micron and 8 micron ranges

  2. Sorption of cesium and strontium by zeolite single crystals

    SciTech Connect

    Burns, R.G.; Wood, V.M.; Morgenstein, M.E.

    1992-08-01

    The aspect ratios of crystals of platey clinoptilolite and fibrous mordenite observed in mineral assemblages coating fractures through tuffs at Yucca Mountain, Nevada, influence the sorption properties of these two zeolites. The crystallographic dependencies of cation exchange reactions have been demonstrated in clinoptilolite by reacting CsCl with oriented single crystals mounted on (100), (010), (001) and (101) faces. Competing cation exchange reactions involving Cs{sup +}, Sr{sup 2+} and Ba{sup 2+}, as well as Cs{sup +} in NaCl or NaHCO{sub 3} solutions, were performed on the oriented zeolite crystals. Reactions were carried out at 60{degrees}C for 1 to 8 weeks in a shaking water bath with dissolved metal chloride solutions ranging in concentrations from 1M to 10{sup {minus}4}M. Electron microprobe analyses were performed on the surfaces of the reacted zeolite crystals. In clinoptilolite, cation exchange is initially retarded on (010) faces which are nominal to the one direction (parallel to the b-axis) along which channels do not exist in the clinoptilolite structure. This orientation effect was particularly severe for Sr, concentrations of which on (010) faces remained 90% lower than values measured on other crystal faces even when reaction times exceeded 2 months. In competition with Sr and Ba, the uptake of Cs into clinoptilolite was lowered significantly (and vice versa for Ba and Sr), particularly in the presence of Ba. The addition of 1M NaCl did not significantly affect the relative concentrations of these competing cations in reacted zeolite crystals. In NaHCO{sub 3} solutions, however, the Cs uptake was lowered significantly. Although clinoptilolite has a very high selectivity for Cs{sup +} compared to other cations, competition with Sr{sup 2+} and Ba{sup 2+} reduces the concentration of Cs{sup +} exchanged into this zeolite. 31 refs., 11 figs.

  3. Petrology of samples from drill holes USW H-3, H-4, and H-5, Yucca Mountain, Nevada

    SciTech Connect

    Levy, S.S.

    1984-06-01

    Hydrology drill holes USW H-3, H-4, and H-5, on the crest and eastern flank of southern Yucca Mountain, Nevada, penetrated a sequence of altered Tertiary pyroclastic rocks consisting of the Paintbrush Tuff, tuff of Calico Hills, and Crater Flat Tuff, in order of increasing age and depth. Multiple episodes of zeolitization are tentatively recognized in the upper Crater Flat Tuff and overlying units from petrologic study of drill bit cuttings and sidewall samples and from studies of samples from other drill holes. The earliest recognized episode was shallow burial diagenesis of Crater Flat Tuff and possibly tuff of Calico Hills before emplacement of the overlying Paintbrush Tuff. Heulandite-clinoptilolite and opal are the main alteration products. A second episode involved crystallization of heulandite and smectite during late-stage devitrification of vitrophyre in the Topopah Spring Member of the Paintbrush Tuff. A third episode of zeolitization, perhaps in part contemporaneous with the second, occurred approximately while the Paintbrush Tuff and older units were being displaced by tilting. Alteration products from this episode of burial diagenesis are clinoptilolite and minor smectite. Mordenite is an additional alteration product in some intervals. A nonlithophysal interval in the lower Topopah Spring tuff is under consideration for placement of a high-level nuclear waste repository. Heulandite and smectite in the altered vitrophyre directly beneath this interval could be the first highly sorptive minerals encountered by contaminated fluid escaping from a repository. Therefore, sorptive properties and thermochemical stability of these specific minerals should be further investigated. 50 references, 16 figures, 1 table.

  4. Physical and chemical properties of zeolite minerals occurring at the Yucca Mountain Site

    SciTech Connect

    Smyth, J.R.

    1988-08-01

    Silica tuffs at Yucca Mountain, Nevada, are under investigation as potential host rocks for isolation of high and intermediate level radioactive wastes from commercial nuclear power generation. Non- welded and partially welded tuffs at this site may contain major amounts (up to 90%) of the zeolite minerals clinoptilolite, mordenite, and analcime. Densely welded tuffs which form the proposed repository horizon and some of the minor basaltic dikes at the site contain clinoptilolite or heulandite as fracture filling which limits the permeability of these rocks. The cation exchange properties of these zeolites allow them to form a natural sorptive barrier to the migration of radionuclides that may move as soluble cationic species in ground water. However, these zeolites are unstable at elevated temperatures and may breakdown either by dehydration at low water-vapor pressures or by mineralogical reaction to more stable phases at higher water-vapor pressures and at relatively low temperatures (80--100{degree}C). All the breakdown reactions occurring with increasing temperature result in significant volume reductions and evolution of fluids. Thus they may provide a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere if heat-generating wastes are emplaced in zeolite-rich horizons. The breakdown reactions and the sorptive properties both vary strongly with zeolite crystal chemistry, and for any given structure, with the exchangeable cations present in that structure. Thus an improved knowledge of the crystal chemistry of these zeolites, particularly clinoptilolite which has not been thoroughly studied due to a scarcity of adequate crystals, will allow improved models of radionuclide migration and a better evaluation of any potential hazards posed by breakdown of these highly temperature-sensitive minerals at the Yucca Mountain site. 38 refs., 5 figs., 2 tabs.

  5. Further description of the petrology of the Topopah Spring member of the paintbrush tuff in drill holes UE25A-1 and USW-G1 and of the lithic-rich tuff in USW-G1, Yucca Mountain, Nevada

    SciTech Connect

    Carroll, P.I.; Caporuscio, F.A.; Bish, D.L.

    1981-11-01

    The Topopah Spring Member of the Paintbrush Tuff and the Lithic-rich tuff and two Tertiary volcanic units that occur in cores from drill holes UE25a-1 and USW-G1 at Yucca Mountain, Nevada. Recently they have been suggested as possibly suitable for the permanent storage of high-level radioactive waste. Earlier petrologic characterization of these units is augmented here. The Topopah Spring Member (approximately 350 m thick) has two compound cooling units. The upper, thinner unit is densely welded to vitrophyric. The lower unit ranges from nonwelded to vitrophyric, and its nonwelded base is extensively zeolitized to clinoptilolite and mordenite. Heulandite occurs as fracture fill in the overlying vitrophyric part, but zeolites are absent above that vitrophyre. Here primary devitrification plus vapor-phase crystallization dominate the mineralogy. Vapor-phase effects are especially prominent between the two vitrophyres in both cores and include numerous large lithophysal cavities throughout most of this moderately to densely welded tuff. The Lithic-rich tuff extends from 1203 to 1506 m in the USW-G1 drill core. It is nonwelded to partly welded but is well indurated due to pervasive intergrowths of authigenic minerals. These phases are analcime, albite, alkali feldspar, sericite, chlorite and quartz. The transition from analcime to secondary albite corresponds to Iijima`s zeolite Zone IV boundary, and this boundary appears in USW-G1 at 1326 m. However, analcime remains as a prominent phase through most of the Lithic-rich tuff. Further work is necessary to assess the suitability of either of these horizons for a waste repository. In the Topopah Spring Member, both mechanical and hydrologic properties of thick lithophysal zone must be studied, as well as the complete sequence of fracture fill. For both units, zeolite and clay mineral stabilities need to be investigated.

  6. Fracture coatings in Topopah Spring Tuff along drill hole wash

    SciTech Connect

    Carlos, B.A.; Chipera, S.J.; Bish, D.L.

    1994-12-01

    Fracture-lining minerals are being studied as part of site characterization to determine the suitability of Yucca Mountain, Nevada as a potential high level nuclear waste repository. Fracture coatings in the Paintbrush Group provide information on potential flow paths above the water table both toward and away from the potential repository and provide information on the distribution of fracture-lining minerals needed to model thermal effects of waste emplacement. Fracture coatings within the predominantly non-zeolitic Paintbrush Group vary both with depth and laterally across Yucca Mountain, whereas fracture coatings in tuffs below the Paintbrush Group are related to the mineralogy of the tuffs and follow a consistent pattern of distribution with predominantly quartz, calcite, and manganese oxides in the devitrified intervals and mordenite and clinoptilolite in the zeolitic intervals. The zeolites stellerite and heulandite are more abundant in fractures in the Topopah Spring Tuff in drill holes USW G-1 and UE-25 a{number_sign}l, located along Drill Hole Wash (at the northern end of Yucca Mountain) than in core from other parts of Yucca Mountain. Buesch et al. (2) present evidence for a complex fault system along Drill Hole Wash. To investigate the possibility that the abundant fracture-lining zeolites in USW G-1 and UE-25 a{number_sign} 1 are related to the Drill Hole Wash fault, the Topopah Spring Tuff was examined in drill cores from USW UZ-14, USW G-1, USW NRG-7/7a, and UE-25 a{number_sign}l.

  7. Stratigraphy, structure, and some petrographic features of Tertiary volcanic rocks at the USW G-2 drill hole, Yucca Mountain, Nye County, Nevada

    SciTech Connect

    Maldonado, F.; Koether, S.L.

    1983-12-31

    A continuously cored drill hole penetrated 1830.6 m of Tertiary volcanic strata comprised of the following in descending order: Paintbrush Tuff, tuffaceous beds of Calico Hills, Crater Flat Tuff, lava and flow breccia (rhyodacitic), tuff of Lithic Ridge, bedded and ash-flow tuff, lava and flow breccia bedded tuff, conglomerate and ash-flow tuff, and older tuffs of USW G-2. Comparison of unit thicknesses at USW G-2 to unit thicknesses at previously drilled holes at Yucca Mountain indicate: (1) thickening of the Paintbrush Tuff members and tuffaceous beds of Calico Hills toward the northern part of Yucca Mountain; (2) thickening of the Prow Pass Member but thinning of the Bullfrog Member and Tram unit; (3) thinning of the tuff of Lithic Ridge; (4) presence of about 280 m of lava and flow breccia not previously penetrated by any drill hole; and (5) presence of an ash-flow tuff unit at the bottom of the drill hole not previously intersected, apparently the oldest unit penetrated at Yucca Mountain to date. Petrographic features of some of the units include: (1) decrease in quartz and K-feldspar and increases in biotite and plagioclase with depth in the tuffaceous beds of Calico Hills; (2) an increase in quartz phenocrysts from the top to the bottom members of the Crater Flat Tuff; (3) a low quartz content in the tuff of Lithic Ridge, suggesting tapping of the magma chamber at quartz-poor levels; (4) a change in zeolitic alteration from heulandite to clinoptilolite to mordenite with increasing depth; (5) lavas characterized by a rhyolitic top and dacitic base, suggesting reverse compositional zoning; and (6) presence of hydrothermal mineralization in the lavas that could be related to an itrusive under Yucca Mountain or to volcanism associated with the Timber Mountain-Claim Canyon caldera complex. A fracture analysis of the core resulted in tabulation of 7848 fractures, predominately open and high angle.

  8. Electron transfer reactions in microporous solids. Progress report, June 1991--May 1992

    SciTech Connect

    Mallouk, T.E.

    1992-05-01

    We have studied electron transfer quenching of the excited state of Ru(bpy){sub 3}{sup 2+} in aqueous suspensions of zeolites Y, L, and mordenite. The internal pore network of the zeolite is ion-exchanged with methylviologen cations, which quench the excited state of the surface-bound sensitizer. A detailed study of the quenching and charge recombination kinetics, using time-resolved luminescence quenching and transient diffuse reflectance spectroscopies, shows to remarkable effects: first, the excited state quenching is entirely dynamic is large-pore zeolites (L and Y), even when they are prepared as apparently ``dry`` powders (which still contain significant amounts of internally sited water). Second, a lower limit for the diffusion coefficient of the MV{sup 2+} ion in these zeolites, determined by this technique, is 10{sup {minus}7} cm{sup 2}sec, i.e., only about one order of magnitude slower than a typical ion in liquid water, and 2--3 orders of magnitude faster than charge transfer diffusion of cations in polyelectrolyte films or membranes such as Nafion. Surface sensitization of internally platinized layered oxide semiconductors such as K{sub 4-x}H{sub x}Nb{sub 6}O{sub 17}{center_dot}nH{sub 2}O (x {approx} 2.5) yields photocatalysts for the production of H{sub 2} and I{sub 3{minus}} in aqueous iodide solutions. Layered alkali niobates and titanates form a class of zeolitic wide-bandap semiconductors, and are the first examples of photocatalysts that evolve hydrogen from an electrochemically reversible (i.e., non-sacrificial) electron donor with visible light excitation.

  9. Electron transfer reactions in microporous solids

    SciTech Connect

    Mallouk, T.E.

    1992-05-01

    We have studied electron transfer quenching of the excited state of Ru(bpy){sub 3}{sup 2+} in aqueous suspensions of zeolites Y, L, and mordenite. The internal pore network of the zeolite is ion-exchanged with methylviologen cations, which quench the excited state of the surface-bound sensitizer. A detailed study of the quenching and charge recombination kinetics, using time-resolved luminescence quenching and transient diffuse reflectance spectroscopies, shows to remarkable effects: first, the excited state quenching is entirely dynamic is large-pore zeolites (L and Y), even when they are prepared as apparently dry'' powders (which still contain significant amounts of internally sited water). Second, a lower limit for the diffusion coefficient of the MV{sup 2+} ion in these zeolites, determined by this technique, is 10{sup {minus}7} cm{sup 2}sec, i.e., only about one order of magnitude slower than a typical ion in liquid water, and 2--3 orders of magnitude faster than charge transfer diffusion of cations in polyelectrolyte films or membranes such as Nafion. Surface sensitization of internally platinized layered oxide semiconductors such as K{sub 4-x}H{sub x}Nb{sub 6}O{sub 17}{center dot}nH{sub 2}O (x {approx} 2.5) yields photocatalysts for the production of H{sub 2} and I{sub 3{minus}} in aqueous iodide solutions. Layered alkali niobates and titanates form a class of zeolitic wide-bandap semiconductors, and are the first examples of photocatalysts that evolve hydrogen from an electrochemically reversible (i.e., non-sacrificial) electron donor with visible light excitation.

  10. Hydrothermal alteration in research drill hole Y-2, Lower Geyser Basin, Yellowstone National Park, Wyoming

    SciTech Connect

    Bargar, K.E.; Beeson, M.H.

    1981-05-01

    Y-2, a US Geological Survey research diamond-drill hole in Lower Geyser Basin, Yellowstone National Park, was drilled to a depth of 157.4 meters. The hole penetrated interbedded siliceous sinter and travertine to 10.2 m, glacial sediments of the Pinedale Glaciation interlayered with pumiceous tuff from 10.2 to 31.7 m, and rhyolitic lavas of the Elephant Back flow of the Central Plateau Member and the Mallard Lake Member of the Pleistocene Plateau Rhyolite from 31.7 to 157.4 m. Hydrothermal alteration is pervasive in most of the nearly continuous drill core. Rhyolitic glass has been extensively altered to clay and zeolite minerals (intermediate heulandite, clinoptilolite, mordenite, montmorillonite, mixed-layer illite-montmorillonite, and illite) in addition to quartz and adularia. Numerous veins, vugs, and fractures in the core contain these and other minerals: silica minerals (opal, ..beta..-cristobalite, ..cap alpha..-cristobalite, and chalcedony), zeolites (analcime, wairakite, dachiardite, laumontite, and yugawaralite), carbonates (calcite and siderite), clay (kaolinite and chlorite), oxides (hematite, goethite, manganite, cryptomelane, pyrolusite, and groutite), and sulfides (pyrhotite and pyrite) along with minor aegirine, fluorite, truscottite, and portlandite. Interbedded travertine and siliceous sinter in the upper part of the drill core indicate that two distinct types of thermal water are responsible for precipitation of the surficial deposits, and further that the water regime has alternated between the two thermal waters more than once since the end of the Pinedale Glaciation (approx. 10,000 years B.P.). Alternation of zones of calcium-rich and sodium- and potassium-rich hydrothermal minerals also suggests that the calcium-rich and sodium- and potassium-rich hydrothermal minerals also suggests that the water chemistry in this drill hole varies with depth.

  11. Methane to acetic acid over Cu-exchanged zeolites: mechanistic insights from a site-specific carbonylation reaction.

    PubMed

    Narsimhan, Karthik; Michaelis, Vladimir K; Mathies, Guinevere; Gunther, William R; Griffin, Robert G; Román-Leshkov, Yuriy

    2015-02-11

    The selective low temperature oxidation of methane is an attractive yet challenging pathway to convert abundant natural gas into value added chemicals. Copper-exchanged ZSM-5 and mordenite (MOR) zeolites have received attention due to their ability to oxidize methane into methanol using molecular oxygen. In this work, the conversion of methane into acetic acid is demonstrated using Cu-MOR by coupling oxidation with carbonylation reactions. The carbonylation reaction, known to occur predominantly in the 8-membered ring (8MR) pockets of MOR, is used as a site-specific probe to gain insight into important mechanistic differences existing between Cu-MOR and Cu-ZSM-5 during methane oxidation. For the tandem reaction sequence, Cu-MOR generated drastically higher amounts of acetic acid when compared to Cu-ZSM-5 (22 vs 4 μmol/g). Preferential titration with sodium showed a direct correlation between the number of acid sites in the 8MR pockets in MOR and acetic acid yield, indicating that methoxy species present in the MOR side pockets undergo carbonylation. Coupled spectroscopic and reactivity measurements were used to identify the genesis of the oxidation sites and to validate the migration of methoxy species from the oxidation site to the carbonylation site. Our results indicate that the Cu(II)-O-Cu(II) sites previously associated with methane oxidation in both Cu-MOR and Cu-ZSM-5 are oxidation active but carbonylation inactive. In turn, combined UV-vis and EPR spectroscopic studies showed that a novel Cu(2+) site is formed at Cu/Al <0.2 in MOR. These sites oxidize methane and promote the migration of the product to a Brønsted acid site in the 8MR to undergo carbonylation. PMID:25562431

  12. Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada

    SciTech Connect

    Waters, A.C.; Carroll, P.R.

    1981-11-01

    Tuffs of the Nevada Test Site are currently under investigation to determine their potential for long-term storage of radioactive waste. As part of this program, hole USW-G1 was drilled to a depth of 6000 ft below the surface, in the central part of the Yucca Mountain area, Nevada Test Site, Nevada. Petrographic study of the USW-G1 core is presented in this report and shows the tuffs (which generally were variably welded ash flows) are partly recrystallized to a variety of secondary minerals. The important alteration products are zeolites (heulandite, clinoptilolite, mordenite and analcime), smectite clays with minor interstratified illite, albite, micas, potassium feldspar, and various forms of silica. Iijima`s zeolite zones I through IV of burial metamorphism can be recognized in the core. Zeolites are first observed at about the 1300-ft depth, and the high-temperature boundary of zeolite stability in this core occurs at about 4350 ft. Analcime persists, either metastably or as a retrograde mineral, deeper in the core. The oxidation state of Fe-Ti oxide minerals, through most of the core, increases as the degree of welding decreases, but towards the bottom of the hole, reducing conditions generally prevail. Four stratigraphic units transected by the core may be potentially favorable sites for a waste repository. These four units, in order of increasing depth in the core, are (1) the lower cooling unit of the Topopah Spring Member, (2) cooling unit II of the Bullfrog Member, (3) the upper part of the Tram tuff, and (4) the Lithic-rich tuff.

  13. Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel

    SciTech Connect

    Matyas, Josef; Engler, Robert K.

    2013-09-01

    The U.S. Department of Energy is currently investigating alternative sorbents for the removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents, Ag0-functionalized silica aerogels, shows great promise as a potential replacement for Ag-bearing mordenites because of its high selectivity and sorption capacity for iodine. Moreover, a feasible consolidation of iodine-loaded Ag0-functionalized silica aerogels to a durable SiO2-based waste form makes this aerogel an attractive choice for sequestering radioiodine. This report provides a preliminary assessment of the methods that can be used to consolidate iodine-loaded Ag0-functionalized silica aerogels into a final waste form. In particular, it focuses on experimental investigation of densification of as prepared Ag0-functionalized silica aerogels powders, with or without organic moiety and with or without sintering additive (colloidal silica), with three commercially available techniques: 1) hot uniaxial pressing (HUP), 2) hot isostatic pressing (HIP), and 3) spark plasma sintering (SPS). The densified products were evaluated with helium gas pycnometer for apparent density, with the Archimedes method for apparent density and open porosity, and with high-resolution scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) for the extent of densification and distribution of individual elements. The preliminary investigation of HUP, HIP, and SPS showed that these sintering methods can effectively consolidate powders of Ag0-functionalized silica aerogel into products of near-theoretical density. Also, removal of organic moiety and adding 5.6 mass% of colloidal silica to Ag0-functionalized silica aerogel powders before processing provided denser products. Furthermore, the ram travel data for SPS indicated that rapid consolidation of powders can be performed at temperatures below 950°C.

  14. Adsorption Model for Off-Gas Separation

    SciTech Connect

    Veronica J. Rutledge

    2011-03-01

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior and feedback loops. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes will provide substantial cost savings and many technical benefits. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed in gPROMS software. Inputs include gas stream constituents, sorbent, and column properties, equilibrium and kinetic data, and inlet conditions. It models dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions for a multiple component gas stream. The simulation outputs component concentrations along the column length as a function of time from which the breakthrough data is obtained. It also outputs temperature along the column length as a function of time and pressure drop along the column length. Experimental data will be input into the adsorption model to develop a model specific for iodine adsorption on silver mordenite as well as model(s) specific for krypton and xenon adsorption. The model will be validated with experimental breakthrough curves. Another future off-gas modeling goal is to develop a model for the unit operation absorption. The off-gas models will be made available via the server or web for evaluation by customers.

  15. Demonstrate Scale-up Procedure for Glass Composite Material (GCM) for Incorporation of Iodine Loaded AgZ.

    SciTech Connect

    Nenoff, Tina M.; Garino, Terry J.; Croes, Kenneth James; Rodriguez, Mark A.

    2015-07-01

    Two large size Glass Composite Material (GCM) waste forms containing AgI-MOR were fabricated. One contained methyl iodide-loaded AgI-MOR that was received from Idaho National Laboratory (INL, Test 5, Beds 1 – 3) and the other contained iodine vapor loaded AgIMOR that was received from Oak Ridge National Laboratory (ORNL, SHB 2/9/15 ). The composition for each GCM was 20 wt% AgI-MOR and 80 wt% Ferro EG2922 low sintering temperature glass along with enough added silver flake to prevent any I2 loss during the firing process. The silver flake amounts were 1.2 wt% for the GCM with the INL AgI-MOR and 3 wt% for the GCM contained the ORNL AgI-MOR. The GCMs, nominally 100 g, were first uniaxially pressed to 6.35 cm (2.5 inch) diameter disks then cold isostatically pressed, before firing in air to 550°C for 1hr. They were cooled slowly (1°C/min) from the firing temperature to avoid any cracking due to temperature gradients. The final GCMs were ~5 cm in diameter (~2 inches) and non-porous with densities of ~4.2 g/cm³. X-ray diffraction indicated that they consisted of the amorphous glass phase with small amounts of mordenite and AgI. Furthermore, the presence of the AgI was confirmed by X-ray fluorescence. Methodology for the scaled up production of GCMs to 6 inch diameter or larger is also presented.

  16. Test results from the GA technologies engineering-scale off-gas treatment system

    SciTech Connect

    Jensen, D.D.; Olguin, L.J.; Wilbourn, R.G.

    1984-06-01

    One method for reducing the volume of HTGR fuel prior to reprocessing or spent fuel storage is to crush and burn the graphite fuel elements. The burner off-gas (BOG) contains radioactive components, principally H-3, C-14, Kr-85, I-129, and Rn-220, as well as chemical forms such as CO/sub 2/, CO, O/sub 2/, and SO/sub 2/. The BOG system employs components designed to remove these constitutents. Test results are reported for the iodine and SO/sub 2/ adsorbers and the CO/HT oxidizer. Silver-based iodine adsorbents were found to catalyze the premature conversion of CO to CO/sub 2/. Subsequent tests showed that iodine removal could not be performed downstream of the CO/HT oxidizer since iodine in the BOG system rapidly deactivated the Pt-coated alumina CO catalyst. Lead-exchanged zeolite (PbX) was found to be an acceptable alternative for removing iodine from BOG without CO conversion. Intermittent and steady-state tests of the pilot-plant SO/sub 2/ removal unit containing sodium-exchanged zeolite (NaX) demonstrated that decontamination factors greater than or equal to 100 could be maintained for up to 50 h. In a reprocessing flowsheet, the solid product from the burners is dissolved in nitric or Thorex acid. The dissolver off-gas (DOG) contains radioactive components H-3, Kr-85, I-129, Rn-220 plus chemical forms such as nitrogen oxides (NO/sub x/). In the pilot-scale system at GA, iodine is removed from the DOG by adsorption. Tests of iodine removal have been conducted using either silver-exchanged mordenite (AgZ) or AgNO/sub 3/-impregnated silica gel (AC-6120). Although each sorbent performed well in the presence of NO/sub x/, the silica gel adsorbent proved more efficient in silver utilization and, thus, more cost effective.

  17. Metal immobilization in soils using synthetic zeolites.

    PubMed

    Oste, Leonard A; Lexmond, Theo M; Van Riemsdijk, Willem H

    2002-01-01

    In situ immobilization of heavy metals in contaminated soils is a technique to improve soil quality. Synthetic zeolites are potentially useful additives to bind heavy metals. This study selected the most effective zeolite in cadmium and zinc binding out of six synthetic zeolites (mordenite-type, faujasite-type, zeolite X, zeolite P, and two zeolites A) and one natural zeolite (clinoptilolite). Zeolite A appeared to have the highest binding capacity between pH 5 and 6.5 and was stable above pH 5.5. The second objective of this study was to investigate the effects of zeolite addition on the dissolved organic matter (DOM) concentration. Since zeolites increase soil pH and bind Ca, their application might lead to dispersion of organic matter. In a batch experiment, the DOM concentration increased by a factor of 5 when the pH increased from 6 to 8 as a result of zeolite A addition. A strong increase in DOM was also found in the leachate of soil columns, particularly in the beginning of the experiment. This resulted in higher metal leaching caused by metal-DOM complexes. In contrast, the free ionic concentration of Cd and Zn strongly decreased after the addition of zeolites, which might explain the reduction in metal uptake observed in plant growth experiments. Pretreatment of zeolites with acid (to prevent a pH increase) or Ca (to coagulate organic matter) suppressed the dispersion of organic matter, but also decreased the metal binding capacity of the zeolites due to competition of protons or Ca. PMID:12026084

  18. Argon Collection And Purification For Proliferation Detection

    SciTech Connect

    Achey, R.; Hunter, D.

    2015-10-09

    In order to determine whether a seismic event was a declared/undeclared underground nuclear weapon test, environmental samples must be taken and analyzed for signatures that are unique to a nuclear explosion. These signatures are either particles or gases. Particle samples are routinely taken and analyzed under the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) verification regime as well as by individual countries. Gas samples are analyzed for signature gases, especially radioactive xenon. Underground nuclear tests also produce radioactive argon, but that signature is not well monitored. A radioactive argon signature, along with other signatures, can more conclusively determine whether an event was a nuclear test. This project has developed capabilities for collecting and purifying argon samples for ultra-low-background proportional counting. SRNL has developed a continuous gas enrichment system that produces an output stream containing 97% argon from whole air using adsorbent separation technology (the flow diagram for the system is shown in the figure). The vacuum swing adsorption (VSA) enrichment system is easily scalable to produce ten liters or more of 97% argon within twelve hours. A gas chromatographic separation using a column of modified hydrogen mordenite molecular sieve has been developed that can further purify the sample to better than 99% purity after separation from the helium carrier gas. The combination of these concentration and purification systems has the capability of being used for a field-deployable system for collecting argon samples suitable for ultra-low-background proportional counting for detecting nuclear detonations under the On-Site Inspection program of the CTBTO verification regime. The technology also has applications for the bulk argon separation from air for industrial purposes such as the semi-conductor industry.

  19. Xe/Kr Selectivity Measurements using AgZ-PAN at Various Temperatures

    SciTech Connect

    Garn, Troy Gerry; Greenhalgh, Mitchell Randy; Watson, Tony Leroy

    2015-05-01

    In preparation for planned FY-15 Xe/Kr multi-column testing, a series of experiments were performed to determine the selectivity of Xe over Kr using the silver converted mordenite-polyacrylonitrile (AgZ-PAN) sorbent. Results from these experiments will be used for parameter selection guidelines to define test conditions for Kr gas capture purity evaluations later this year. The currently configured experimental test bed was modified by installing a new cooling apparatus to permit future multi-column testing with independent column temperature control. The modified test bed will allow for multi-column testing to facilitate a Xe separation followed by a Kr separation using engineered form sorbents. Selectivity experiments were run at temperatures of 295, 250 and 220 K. Two feed gas compositions of 1000 ppmv Xe, 150 ppmv Kr in either a He or an air balance were used. AgZ-PAN sorbent selectivity was calculated using Xe and Kr capacity determinations. AgZ-PAN sorbent selectivities for Xe over Kr of 72 were calculated at room temperature (295 K) using the feed gas with a He balance and 34 using the feed gas with an air balance. As the test temperatures were decreased the selectivity of Xe over Kr also decreased due to an increase in both Xe and Kr capacities. At 220 K, the sorbent selectivities for Xe over Kr were 22 using the feed gas with a He balance and 28 using the feed gas with an air balance. The selectivity results indicate that AgZ-PAN used in the first column of a multi-column configuration will provide adequate partitioning of Xe from Kr in the tested temperature range to produce a more pure Kr end product for collection.

  20. Zeolite-supported metal complexes of rhodium and of ruthenium: a general synthesis method influenced by molecular sieving effects.

    PubMed

    Ogino, Isao; Chen, Cong-Yan; Gates, Bruce C

    2010-09-28

    A general method for synthesis of supported metal complexes having a high degree of uniformity is presented, whereby organometallic precursors incorporating acetylacetonate (C(5)H(7)O(2)(-), acac) ligands react with zeolites incorporating OH groups near Al sites. The method is illustrated by the reactions of Rh(acac)(CO)(2) and of cis-Ru(acac)(2)(eta(2)-C(2)H(4))(2) with zeolites slurried in n-pentane at room temperature. The zeolites were H-Beta, H-SSZ-42, H-Mordenite, and HZSM-5. Infrared (IR) and extended X-ray absorption fine structure spectra of the zeolites incorporating rhodium complexes indicate the formation of Rh(CO)(2)(+) bonded near Al sites; similar results have been reported for the formation of zeolite-supported Rh(eta(2)-C(2)H(4))(2)(+) from Rh(acac)(eta(2)-C(2)H(4))(2). IR spectra of the supported rhodium gem-dicarbonyls include sharp, well-resolved nu(CO) bands, demonstrating that the sites surrounding each metal complex are nearly equivalent. The frequencies of the nu(CO) bands show how the composition of the zeolite influences the bonding of the supported species, demonstrating subtle differences in the roles of the zeolite as ligands. When the zeolite has pore openings larger than the critical diameter of the precursor organometallic compound, the latter undergoes facile transport into the interior of the zeolite, so that a uniform distribution of the supported species results, but when the precursors barely fit through the zeolite apertures, the mass transport resistance is significant and the supported metal complexes are concentrated near the pore mouths. PMID:20454735

  1. Malignant mesothelioma induced by asbestos and zeolite in the mouse peritonenal cavity

    SciTech Connect

    Suzuki, Y.; Kohyama, N.

    1984-10-01

    The carcinogenicity of asbestos (amosite and chrysotile) and zeolite (fibrous erionite, mordenite, and synthetic zeolite 4A) were studied in the peritoneum of 586 BALB/C male mice after a single intraperitoneal or intraabdominal wall injection. Tumors developed in 93 of 394 animals (23.6%) treated with asbestos or fibrous erionite 7 months or more after administration. All of the induced peritoneal tumors were intimately associated with marked peritoneal fibrosis, in which asbestos or erionite fibers were regularly detected. Histopathologically, 83 of 93 were consistent with malignant mesotheliomas. Other tumors consisted of 6 plasmacytomas, 1 histiocytoma, 1 liposarcoma, 1 osteosarcoma, and 1 adenocarcinoma of the pancreas. Two of the cases of mesotheliomas were associated with plasmacytoma. In many instances, the primary site of the mesotheliomas seemed to be multiple, the favorite sites being the omentum, mesentery, serosae of the gastrointestinal and genital organs, the diaphragm, the capsule of the liver and spleen, and the abdominal wall peritoneum. In addition to the 93 peritoneal tumors, 3 extraperitoneal tumors (1 fibrosarcoma and 2 rhabdomyosarcomas) were induced by amosite which was probably accidentally injected into the extraperitoneal connective tissue and the striated muscle tissue of the abdominal wall, respectively. These three tumors were also intimately associated with focal fibrosis in which amosite fibers were detected. Among the three different types of zeolite, only fibrous erionite showed striking carcinogenicity and marked fibrogenicity. The erionite-induced mesotheliomas were similar to those induced by asbestos in exhibiting long latency, in gross appearance, in histology, and in close association with fibrosis.

  2. Ion exchange and dehydration experimental studies of clinoptilolite: Implications to zeolite dating

    SciTech Connect

    WoldeGabriel, G.

    1995-02-01

    Variable effects were noted on the argon (Ar) and potassium (K) contents of clinoptilolite fractions used in ion-exchange and dehydration experiments. The K contents of clinoptilolite fractions were differently affected during cation exchange with Ca-, Cs-, K-, and Na-chloride solutions. Ar was generally less affected during these experiments, except for a Na-clinoptitolite fraction exchanged for five days. Loss of Ar during organic heavy-liquid treatment and cleaning using acetone and deionized water does occur, as indicated by comparing the amounts of radiogenic Ar of treated and untreated fractions. Moreover, a regular decrease in radiogenic Ar contents was noted in clinoptilolite fractions during dehydration experiments at different temperatures for 16 hours. Comparable losses do not occur from saturated samples that were heated in 100 C for more than five months. Water appears to play a vital role in stabilizing the clinoptilolite framework structure and in the retention of Ar. The radiogenic Ar depletion pattern noted in clinoptilolite fractions dehydrated in unsaturated environment at different temperatures is similar to variations in the amount of radiogenic Ar observed in clinoptilolite samples from the unsaturated zone of an altered tuff. These results can be used to evaluate the extent of zeolitic water (and hence Ar) retention in unsaturated geologic settings. The utility of alkali zeolites (e.g., phillipsite, clinoptilolite, and mordenite) from low-temperature, open-hydrologic alteration as potential dateable minerals was evaluated using the K/Ar method as part of the Yucca Mountain Site Characterization Project, which is evaluating Yucca Mountain, Nevada, as a potential high-level radioactive waste repository site.

  3. Electron transfer reactions in microporous solids

    NASA Astrophysics Data System (ADS)

    Mallouk, T. E.

    1992-05-01

    We have studied electron transfer quenching of the excited state of Ru3(2+) in aqueous suspensions of zeolites Y, L, and mordenite. The internal pore network of the zeolite is ion-exchanged with methylviologen cations, which quench the excited state of the surface-bound sensitizer. A detailed study of the quenching and charge recombination kinetics, using time-resolved luminescence quenching and transient diffuse reflectance spectroscopies, shows two remarkable effects: first, the excited state quenching is entirely dynamic is large-pore zeolites (L and Y), even when they are prepared as apparently 'dry' powders (which still contain significant amounts of internally sited water). Second, a lower limit for the diffusion coefficient of the MV(2+) ion in these zeolites, determined by this technique, is 10(exp -7) sq cm sec, i.e., only about one order of magnitude slower than a typical ion in liquid water, and 2 to 3 orders of magnitude faster than charge transfer diffusion of cations in polyelectrolyte films or membranes such as Nafion. Surface sensitization of internally platinized layered oxide semiconductors such as K(4-x)H(x)Nb6O17 - nH2O(x approx. = 2.5) yields photocatalysts for the production of H2 and I3(-) in aqueous iodide solutions. Layered alkali niobates and titanates form a class of zeolitic wide-bandap semiconductors, and are the first examples of photocatalysts that evolve hydrogen from an electrochemically reversible (i.e., non-sacrificial) electron donor with visible light excitation.

  4. Distribution of Components in Ion Exchange Materials Taken from the K East Basin and Leaching of Ion Exchange Materials by Nitric/Hydrofluoric Acid and Nitric/Oxalic Acid

    SciTech Connect

    Delegard, C.H.; Rinehart, D.E.; Hoopes, F.V.

    1999-04-02

    Laboratory tests were performed to examine the efficacy of mixed nitric/hydrofluoric acid followed by mixed nitric/oxalic acid leach treatments to decontaminate ion exchange materials that have been found in a number of samples retrieved from K East (KE)Basin sludge. The ion exchange materials contain organic ion exchange resins and zeolite inorganic ion exchange material. Based on process records, the ion exchange resins found in the K Basins is a mixed-bed, strong acid/strong base material marketed as Purolite NRW-037. The zeolite material is Zeolon-900, a granular material composed of the mineral mordenite. Radionuclides sorbed or associated with the ion exchange material can restrict its disposal to the Environmental Restoration Disposal Facility (ERDF). The need for testing to support development of a treatment process for K Basin sludge has been described in Section 4.2 of ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process'' (Flament 1998). Elutriation and washing steps are designed to remove the organic resins from the K Basin sludge. To help understand the effects of the anticipated separation steps, tests were performed with well-rinsed ion exchange (IX) material from KE Basin floor sludge (sample H-08 BEAD G) and with well-rinsed IX having small quantities of added KE canister composite sludge (sample KECOMP). Tests also were performed to determine the relative quantities of organic and inorganic IX materials present in the H-08 K Basin sludge material. Based on chemical analyses of the separated fractions, the rinsed and dry IX material H-08 BEAD G was found to contain 36 weight percent inorganic material (primarily zeolite). The as-received (unrinsed) and dried H-08 material was estimated to contain 45 weight percent inorganic material.

  5. Distribution and chemistry of fracture-lining minerals at Yucca Mountain, Nevada

    SciTech Connect

    Carlos, B.A.; Chipera, S.J.; Bish, D.L.

    1995-12-01

    Yucca Mountain, a >1.5-km-thick sequence of tuffs and subordinate lavas in southwest Nevada, is being investigated as a potential high-level nuclear waste repository site. Fracture-lining minerals have been studied because they may provide information on past fluid transport and because they may act as natural barriers to radionuclide migration within the fractures. Cores from seven drill holes have been studied to determine the distribution and chemistry of minerals lining fractures at Yucca Mountain. Fracture-lining minerals in tuffs of the Paintbrush Group, which is above the static water level at Yucca Mountain, are highly variable in distribution, both vertically and laterally across the mountain, with the zeolites mordenite, heulandite, and stellerite widespread in fractures even though the tuff matrix is generally devitrified and nonzeolitic. Where heulandite occurs as both tabular and prismatic crystals in the same fracture, the two morphologies have different compositions, suggesting multiple episodes of zeolite formation within the fractures. Manganese-oxide minerals within the Paintbrush Group are rancieite and lithiophorite. The silica polymorphs (quartz, tridymite, and cristobalite) generally exist in fractures where they exist in the matrix, suggesting that they formed in the fractures at the same time they formed in the matrix. Fluorite, calcite, and opal occur over tridymite in some lithophysal cavities. Calcite also occurs over zeolites in fractures unrelated to lithophysal cavities and is often the youngest mineral in a given fracture. The clays smectite, palygorskite, and sepiolite are common in fractures in the Paintbrush Group in drill core USW GU-3; smectite is an abundant fracture-coating mineral in all drill cores at Yucca Mountain.

  6. Neutron Scattering Studies of Fundamental Processes in Earth Materials, Final Report

    SciTech Connect

    McCall, K. R.

    2007-06-11

    The aim of this work was to use neutron scattering techniques to explore the dynamics and structure of water in rock samples. The dynamics of water in rock at low (residual) saturation are directly related to the transport properties of fluids within the host rock. The structure of water in rock may be related to the elastic behavior of the rock, which in many cases is nonlinear and hysteretic. Neutron scattering techniques allow us to study water in intact rock samples at both the molecular and microstructural scales. Our samples were Berea sandstone, Calico Hills and Prow Pass tuffs from Yucca Mountain, NV, and pure samples of the tuff constituents, specifically mordenite and clinoptilolite. We chose Berea sandstone because its macroscopic elastic behavior is known to be highly unusual, and the microscopic mechanisms producing this behavior are not understood. We chose Yucca Mountain tuff, because the fluid transport properties of the geologic structure at Yucca Mountain, Nevada could be relevant to the performance of a high level nuclear waste repository at that site. Neutron scattering methods have a number of properties that are extremely useful for the study of earth materials. In contrast to X-rays, neutrons have very low absorption cross-sections for most elements so that entire bulk samples of considerable size can be 'illuminated' by the neutron beam. Similarly, samples that are optically opaque can be readily investigated by inelastic neutron scattering techniques. Neutrons are equally sensitive to light atoms as to heavy atoms, and can, for example, readily distinguish between Al and Si, neighboring atoms in the periodic table that are difficult to tell apart by X-ray diffraction. Finally, neutrons are particularly sensitive to hydrogen and thus can be used to study the motions, both vibrational and diffusive, of H-containing molecules in rocks, most notably of course, water. Our studies were primarily studies of guest molecules (in our case, water) in

  7. Spectroscopic study of the dehydration and/or dehydroxylation of phyllosilicate and zeolite minerals

    NASA Astrophysics Data System (ADS)

    Che, Congcong; Glotch, Timothy D.; Bish, David L.; Michalski, Joseph R.; Xu, Wenqian

    2011-05-01

    at ˜900 cm-1 upon heating to 800°C. Compared with phyllosilicates, spectral features of two natural zeolites, clinoptilolite and mordenite, are less affected by thermal treatments. Even after heating to 900°C, the IR spectral features attributed to Si (Al)-O stretching and bending vibration modes do not show significant differences from those of unheated zeolites.

  8. Structure-property relationship of metal-organic frameworks (MOFs) and physisorbed off-gas radionuclides.

    SciTech Connect

    Nenoff, Tina Maria; Chupas, Peter J.; Garino, Terry J.; Rodriguez, Mark Andrew; Chapman, Karena W.; Sava, Dorina Florentina

    2010-11-01

    We report on the host-guest interactions between metal-organic frameworks (MOFs) with various profiles and highly polarizable molecules (iodine), with emphasis on identifying preferential sorption sites in these systems. Radioactive iodine 129I, along with other volatile radionuclides (3H, 14C, Xe and Kr), represents a relevant component in the off-gas resulted during nuclear fuel reprocessing. Due to its very long half-life, 15.7 x 106 years, and potential health risks in humans, its efficient capture and long-term storage is of great importance. The leading iodine capture technology to date is based on trapping iodine in silver-exchanged mordenite. Our interests are directed towards improving existent capturing technologies, along with developing novel materials and alternative waste forms. Herein we report the first study that systematically monitors iodine loading onto MOFs, an emerging new class of porous solid-state materials. In this context, MOFs are of particular interest as: (i) they serve as ideal high capacity storage media, (ii) they hold potential for the selective adsorption from complex streams, due to their high versatility and tunability. This work highlights studies on both newly developed in our lab, and known highly porous MOFs that all possess distinct characteristics (specific surface area, pore volume, pore size, and dimension of the window access to the pore). The materials were loaded to saturation, where elemental iodine was introduced from solution, as well as from vapor phase. Uptakes in the range of {approx}125-150 wt% I2 sorbed were achieved, indicating that these materials outperform all other solid adsorbents to date in terms of overall capacity. Additionally, the loaded materials can be efficiently encapsulated in stable waste forms, including as low temperature sintering glasses. Ongoing studies are focused on gathering qualitative information with respect to localizing the physisorbed iodine molecules within the frameworks: X

  9. A call to expand regulation to all carcinogenic fibrous minerals

    NASA Astrophysics Data System (ADS)

    Baumann, F.; Steele, I.; Ambrosi, J.; Carbone, M.

    2013-05-01

    The regulatory term "asbestos" groups only the six fibrous minerals that were commercially used among approximately 400. The carcinogenicity of these six regulated minerals has been largely demonstrated and is related to fiber structure, fiber length/diameter ratio, and bio-persistence. From a public perception, the generic term "asbestos" refers to the fibrous minerals that cause asbestosis, mesothelioma and other cancers. However, other non-regulated fibrous minerals are potentially as dangerous as the regulatory asbestos because they share similar physical and chemical properties, epidemiological studies have demonstrated their relationship with asbestos-related diseases, and both in vitro and in vivo experiments have established the toxicity of these minerals. For example, the non-regulated asbestiform winchite and richterite minerals that contaminated the vermiculite mined from Libby, Montana, (USA) were associated with mesothelioma, lung cancer and asbestosis observed among the area's residents and miners. Many other examples of non-regulated carcinogenic fibrous minerals include, but are not limited to, antigorite, arfvedsonite, balangeroite, carlosturanite, erionite, fluoro-edenite, hornblende, mordenite, palygorskite, and sepiolite. To propose a regulatory definition that would provide protection from all carcinogenic fibers, we have conducted an interdisciplinary literature review to compare the characteristics of "asbestos" and of non-regulated mineral fibers that relate to carcinogenicity. We specifically studied two non-regulated fibrous minerals that are associated with asbestos-related diseases: the serpentine antigorite and the zeolite erionite. Both examples underscore the problem of regulation based on commercial, rather than scientific principles: 1) the occurrence of fibrous antigorite in materials used to pave roads has been correlated with high mesothelioma rates in New Caledonia. Antigorite was also the cause of asbestosis in Poland, and in

  10. Adsorption of Amino Acids (Ala, Cys, His, Met) on Zeolites: Fourier Transform Infrared and Raman Spectroscopy Investigations

    NASA Astrophysics Data System (ADS)

    Carneiro, Cristine E. A.; de Santana, Henrique; Casado, Clara; Coronas, Joaquin; Zaia, Dimas A. M.

    2011-06-01

    Minerals adsorb more amino acids with charged R-groups than amino acids with uncharged R-groups. Thus, the peptides that form from the condensation of amino acids on the surface of minerals should be composed of amino acid residues that are more charged than uncharged. However, most of the amino acids (74%) in today's proteins have an uncharged R-group. One mechanism with which to solve this paradox is the use of organophilic minerals such as zeolites. Over the range of pH (pH 2.66-4.50) used in these experiments, the R-group of histidine (His) is positively charged and neutral for alanine (Ala), cysteine (Cys), and methionine (Met). In acidic hydrothermal environments, the pH could be even lower than those used in this study. For the pH range studied, the zeolites were negatively charged, and the overall charge of all amino acids was positive. The conditions used here approximate those of prebiotic Earth. The most important finding of this work is that the relative concentrations of each amino acid (X=His, Met, Cys) to alanine (X/Ala) are close to 1.00. This is an important result with regard to prebiotic chemistry because it could be a solution for the paradox stated above. Pore size did not affect the adsorption of Cys and Met on zeolites, and the Si/Al ratio did not affect the adsorption of Cys, His, and Met. ZSM-5 could be used for the purification of Cys from other amino acids (Student-Newman-Keuls test, p<0.05), and mordenite could be used for separation of amino acids from each other (Student-Newman-Keuls test, p<0.05). As shown by Fourier transform infrared (FT-IR) spectra, Ala interacts with zeolites through the group, and methionine-zeolite interactions involve the COO, , and CH3 groups. FT-IR spectra show that the interaction between the zeolites and His is weak. Cys showed higher adsorption on all zeolites; however, the hydrophobic Van der Waals interaction between zeolites and Cys is too weak to produce any structural changes in the Cys groups (amine

  11. Quantification of unsaturated-zone alteration and cation exchange in zeolitized tuffs at Yucca Mountain, Nevada, USA

    NASA Astrophysics Data System (ADS)

    Vaniman, David T.; Chipera, Steve J.; Bish, David L.; Carey, J. William; Levy, Schön S.

    2001-10-01

    Zeolitized horizons in the unsaturated zone (UZ) at Yucca Mountain, Nevada, USA, are an important component in concepts for a high-level nuclear waste repository at this site. The use of combined quantitative X-ray diffraction and geochemical analysis allows measurement of the chemical changes that accompanied open-system zeolitization at Yucca Mountain. This approach also provides measures of the extent of chemical migration that has occurred in these horizons as a result of subsequent cation exchange. Mass-balance analysis of zeolitized horizons with extensive cation exchange (drill hole UZ-16) and with only minimal cation exchange (drill hole SD-9) shows that Al is essentially immobile. Although zeolitization occurred in an open system, the mass transfer of constituents other than water is relatively small in initial zeolitization, in contrast to the larger scales of cation exchange that can occur after zeolites have formed. Cation exchange in the clinoptilolite ± mordenite zeolitized horizons is seen in downward-diminishing concentration gradients of Ca, Mg, and Sr exchanged for Na and (to lesser extent) K. Comparison with data from drill hole SD-7, which has multiple zeolitized horizons above the water table, shows that the upper horizons accumulate Ca, Mg, and Sr to such an extent that transport of these elements to the deepest UZ zeolitized horizon can be blocked. Quantitative analysis of zeolite formation yields insight into processes that are implied from laboratory studies and modeling efforts but are otherwise unverified at the site. Such analysis also yields information not provided by or contradicted by some models of flow and transport. The results include the following: (1) evidence of effective downward flow through zeolitic horizons despite the low permeability of these horizons, (2) evidence that alkaline-earth elements accumulated by zeolites are mostly derived from eolian materials in surface soils, (3) validation of the very effective

  12. Geology of the Mid-Miocene Rooster Comb Caldera and Lake Owyhee Volcanic Field, eastern Oregon: Silicic volcanism associated with Grande Ronde flood basalt

    NASA Astrophysics Data System (ADS)

    Benson, Thomas R.; Mahood, Gail A.

    2016-01-01

    The Lake Owyhee Volcanic Field (LOVF) of eastern Oregon consists of rhyolitic caldera centers and lava fields contemporaneous with and spatially related to Mid-Miocene Columbia River flood basalt volcanism. Previous studies delineated two calderas in the southeastern part of LOVF near Owyhee Reservoir, the result of eruptions of two ignimbrites, the Tuff of Leslie Gulch and the Tuff of Spring Creek. Our new interpretation is that these two map units are differentially altered parts of a single ignimbrite produced in a major phreatomagmatic eruption at ~ 15.8 Ma. Areas previously mapped as Tuff of Spring Creek are locations where the ignimbrite contains abundant clinoptilolite ± mordenite, which made it susceptible to erosion. The resistant intracaldera Tuff of Leslie Gulch has an alteration assemblage of albite ± quartz, indicative of low-temperature hydrothermal alteration. Our new mapping of caldera lake sediments and pre- and post-caldera rhyolitic lavas and intrusions that are chemically similar to intracaldera Tuff of Leslie Gulch point to a single ~ 20 × 25 km caldera, which we name the Rooster Comb Caldera. Erosion of the resurgently uplifted southern half of the caldera created dramatic exposures of intracaldera Tuff of Leslie Gulch cut by post-caldera rhyolite dikes and intrusions that are the deeper-level equivalents of lava domes and flows that erupted into the caldera lake preserved in exposures to the northeast. The Rooster Comb Caldera has features in common with more southerly Mid-Miocene calderas of the McDermitt Volcanic Field and High Rock Caldera Complex, including formation in a basinal setting shortly after flood basalt eruptions ceased in the region, and forming on eruption of peralkaline ignimbrite. The volcanism at Rooster Comb Caldera postdates the main activity at McDermitt and High Rock, but, like it, begins ~ 300 ky after flood basalt volcanism begins in the area, and while flood basalts don't erupt through the silicic focus, are

  13. Long-term product consistency test of simulated 90-19/Nd HLW glass

    NASA Astrophysics Data System (ADS)

    Gan, X. Y.; Zhang, Z. T.; Yuan, W. Y.; Wang, L.; Bai, Y.; Ma, H.

    2011-01-01

    Chemical durability of 90-19/Nd glass, a simulated high-level waste (HLW) glass in contact with the groundwater was investigated with a long-term product consistency test (PCT). Generally, it is difficult to observe the long term property of HLW glass due to the slow corrosion rate in a mild condition. In order to overcome this problem, increased contacting surface ( S/ V = 6000 m -1) and elevated temperature (150 °C) were employed to accelerate the glass corrosion evolution. The micro-morphological characteristics of the glass surface and the secondary minerals formed after the glass alteration were analyzed by SEM-EDS and XRD, and concentrations of elements in the leaching solution were determined by ICP-AES. In our experiments, two types of minerals, which have great impact on glass dissolution, were found to form on 90-19/Nd HLW glass surface when it was subjected to a long-term leaching in the groundwater. One is Mg-Fe-rich phyllosilicates with honeycomb structure; the other is aluminosilicates (zeolites). Mg and Fe in the leaching solution participated in the formation of phyllosilicates. The main components of phyllosilicates in alteration products of 90-19/Nd HLW glass are nontronite (Na 0.3Fe 2Si 4O 10(OH) 2·4H 2O) and montmorillonite (Ca 0.2(Al,Mg) 2Si 4O 10(OH) 2·4H 2O), and those of aluminosilicates are mordenite ((Na 2,K 2,Ca)Al 2Si 10O 24·7H 2O)) and clinoptilolite ((Na,K,Ca) 5Al 6Si 30O 72·18H 2O). Minerals like Ca(Mg)SO 4 and CaCO 3 with low solubility limits are prone to form precipitant on the glass surface. Appearance of the phyllosilicates and aluminosilicates result in the dissolution rate of 90-19/Nd HLW glass resumed, which is increased by several times over the stable rate. As further dissolution of the glass, both B and Na in the glass were found to leach out in borax form.

  14. Geological, mineralogical and geochemical characteristics of zeolite deposits associated with borates in the Bigadiç, Emet and Kirka Neogene lacustrine basins, western Turkey

    NASA Astrophysics Data System (ADS)

    Gündogdu, M. N.; Yalçin, H.; Temel, A.; Clauer, N.

    1996-09-01

    place during the diagenetic transformation of rhyolitic glasses to dioctahedral smectites or clinoptilolite. The absence of sodic zeolites such as mordenite, erionite, chabazite and silica-rich phillipsite is mainly due to the very high K/Na ratio of the starting materials rather than initial alkaline conditions or high Na content in lake waters.

  15. Minerals produced during cooling and hydrothermal alteration of ash flow tuff from Yellowstone drill hole Y-5

    USGS Publications Warehouse

    Keith, T.E.C.; Muffler, L.J.P.

    1978-01-01

    A rhyolitic ash-flow tuff in a hydrothermally active area within the Yellowstone caldera was drilled in 1967, and cores were studied to determine the nature and distribution of primary and secondary mineral phases. The rocks have undergone a complex history of crystallization and hydrothermal alteration since their emplacement 600,000 years ago. During cooling from magmatic temperatures, the glassy groundmass underwent either devitrification to alkali feldspar + ??-cristobalite ?? tridymite or granophyric crystallization to alkali feldspar + quartz. Associated with the zones of granophyric crystallization are prismatic quartz crystals in cavities similar to those termed miarolitic in plutonic rocks. Vapor-phase alkali feldspar, tridymite, magnetite, and sporadic ??-cristobalite were deposited in cavities and in void spaces of pumice fragments. Subsequently, some of the vapor-phase alkali feldspar crystals were replaced by microcrystalline quartz, and the vapor-phase minerals were frosted by a coating of saccharoidal quartz. Hydrothermal minerals occur primarily as linings and fillings of cavities and fractures and as altered mafic phenocrysts. Chalcedony is the dominant mineral related to the present hydrothermal regime and occurs as microcrystalline material mixed with various amounts of hematite and goethite. The chalcedony displays intricate layering and was apparently deposited as opal from silica-rich water. Hematite and goethite also replace both mafic phenocrysts and vapor-phase magnetite. Other conspicuous hydrothermal minerals include montmorillonite, pyrite, mordenite, calcite, and fluorite. Clinoptilolite, erionite, illite, kaolinite, and manganese oxides are sporadic. The hydrothermal minerals show little correlation with temperature, but bladed calcite is restricted to a zone of boiling in the tuff and clearly was deposited when CO2 was lost during boiling. Fractures and breccias filled with chalcedony are common throughout Y-5 and may have been

  16. Airborne waste management technology applicable for use in reprocessing plants for control of iodine and other off-gas constituents

    SciTech Connect

    Jubin, R.T.

    1988-02-01

    Extensive work in the area of iodine removal from reprocessing plant off-gas streams using various types of solid sorbent materials has been conducted worldwide over the past two decades. This work has focused on the use of carbon filters, primarily for power plant applications. More recently, the use of silver-containing sorbents has been the subject of considerable research. The most recent work in the United States has addressed the use of silver-exchanged faujasites and mordenites. The chemical reactions of iodine with silver on the sorbent are not well defined, but it is generally believed that chemisorbed iodides and iodates are formed. The process for iodine recovery generally involves passage of the iodine-laden gas stream through a packed bed of the adsorbent material preheated to a temperature of about 150/degree/C. Most iodine removal system designs utilizing silver-containing solid sorbents assume only a 30 to 50% silver utilization. Based on laboratory tests, potentially 60 to 70% of the silver contained in the sorbents can be reacted with iodine. To overcome the high cost of silver associated with these materials, various approaches have been explored. Among these are the regeneration of the silver-containing sorbent by stripping the iodine and trapping the iodine on a sorbent that has undergone only partial silver exchange and is capable of attaining a much higher silver utilization. This summary report describes the US work in regeneration of iodine-loaded solid sorbent material. In addition, the report discusses the broader subject of plant off-gas treatment including system design. The off-gas technologies to recovery No/sub x/ and to recover and dispose of Kr, /sup 14/C, and I are described as to their impacts on the design of an integrated off-gas system. The effect of ventilation philosophy for the reprocessing plant is discussed as an integral part of the overall treatment philosophy of the plant off-gas. 103 refs., 5 figs., 8 tabs.

  17. Petrology and hydrothermal mineralogy of U.S. geological survey Newberry: 2. Drill core from Newberry Caldera, Oregon

    NASA Astrophysics Data System (ADS)

    Keith, Terry E. C.; Bargar, Keith E.

    1988-09-01

    U.S. Geological Survey Newberry 2 was drilled to a depth of 932 m within Newberry caldera. The bottom-hole temperature of 265°C is the highest reported temperature of any drill hole in the Cascades region of the United States. The upper part of the stratigraphic section penetrated by Newberry 2 consists of caldera fill below which are increasingly more mafic lavas ranging from rhyodacite at 501 m to basalt at 932 m. Measured temperatures shallower than 300 m are less than 35°C, and rock alteration consists of hydration of glass and local palagonitization of basaltic tuffs. Incipient zeolitization and partial smectite replacement of ash and pumice occurred throughout the pumiceous lithic tuffs from 300 to 500 m. Higher-temperature alteration of the tuffs to chlorite and mordenite occurs adjacent to a rhyodacite sill at 460-470 m; alteration minerals within the sill consist of pyrrhotite, pyrite, quartz, calcite, and siderite. Below 697 m the rocks are progressively more altered with depth mainly because of increased temperature along a conductive gradient from 100°C at 697 m to 265°C at 930 m. Fluid inclusions in quartz and calcite indicate that temperatures in the past have been higher than at present, most likely due to local confining pressures between impermeable lava flows. Flow breccias are more altered than the adjacent dense massive lava flows, regardless of composition, because of their much higher permeability. Hydrothermal minerals in this zone are mainly mixed-layer chlorite-smectite, quartz, calcite, and pyrite. Chlorite becomes more abundant than mixed-layer clays near the bottom of the hole. In the lowest two lava flows, epidote, anhydrite, and scarce hematite occur locally. Alteration and leaching in the basal 2 m are unique and have led to the postulation of a localized two-phase fluid zone consisting mainly of steam and CO2. The hydrothermal system of Newberry 2 is a simple evolving system associated with the evolution of Newberry Volcano. Only

  18. FINAL REPORT REGULATORY OFF GAS EMISSIONS TESTING ON THE DM1200 MELTER SYSTEM USING HLW AND LAW SIMULANTS VSL-05R5830-1 REV 0 10/31/05

    SciTech Connect

    KRUGER AA; MATLACK KS; GONG W; BARDAKCI T; D'ANGELO NA; BRANDYS M; KOT WK; PEGG IL

    2011-12-29

    The operational requirements for the River Protection Project - Waste Treatment Plant (RPP-WTP) Low Activity Waste (LAW) and High Level Waste (HLW) melter systems, together with the feed constituents, impose a number of challenges to the off-gas treatment system. The system must be robust from the standpoints of operational reliability and minimization of maintenance. The system must effectively control and remove a wide range of solid particulate matter, acid mists and gases, and organic constituents (including those arising from products of incomplete combustion of sugar and organics in the feed) to concentration levels below those imposed by regulatory requirements. The baseline design for the RPP-WTP LAW primary off-gas system includes a submerged bed scrubber (SBS), a wet electrostatic precipitator (WESP), and a high efficiency particulate air (HEPA) filter. The secondary off-gas system includes a sulfur-impregnated activated carbon bed (AC-S), a thermal catalytic oxidizer (TCO), a single-stage selective catalytic reduction NOx treatment system (SCR), and a packed-bed caustic scrubber (PBS). The baseline design for the RPP-WTP HLW primary off-gas system includes an SBS, a WESP, a high efficiency mist eliminator (HEME), and a HEPA filter. The HLW secondary off-gas system includes a sulfur-impregnated activated carbon bed, a silver mordenite bed, a TCO, and a single-stage SCR. The one-third scale HLW DM1200 Pilot Melter installed at the Vitreous State Laboratory (VSL) was equipped with a prototypical off-gas train to meet the needs for testing and confirmation of the performance of the baseline off-gas system design. Various modifications have been made to the DM1200 system as the details of the WTP design have evolved, including the installation of a silver mordenite column and an AC-S column for testing on a slipstream of the off-gas flow; the installation of a full-flow AC-S bed for the present tests was completed prior to initiation of testing. The DM1200

  19. Stratigraphy, structure, and some petrographic features of Tertiary volcanic rocks in the USW G-2 drill hole, Yucca Mountain, Nye County, Nevada

    USGS Publications Warehouse

    Maldonado, Florian; Koether, S.L.

    1983-01-01

    A continuously cored drill hole designated as USW G-2, located at Yucca Mountain in southwestern Nevada, penetrated 1830.6 m of Tertiary volcanic strata composed of abundant silicic ash-flow tuffs, minor lava and flow breccias, and subordinate volcaniclastic rocks. The volcanic strata penetrated are comprised of the following in descending order: Paintbrush Tuff (Tiva Canyon Member, Yucca Mountain Member, bedded tuff, Pah Canyon Member, and Topopah Spring Member), tuffaceous beds of Calico Hills, Crater Flat Tuff (Prow Pass Member, Bullfrog Member, and Tram unit), lava and flow breccia (rhyodacitic), tuff of Lithic Ridge, bedded and ash-flow tuff, lava and flow breccia (rhyolitic, quartz latitic, and dacitic), bedded tuff, conglomerate and ash-flow tuff, and older tuffs of USW G-2. Comparison of unit thicknesses at USW G-2 to unit thicknesses at previously drilled holes at Yucca Mountain indicate the following: (1) thickening of the Paintbrush Tuff members and tuffaceous beds of Calico Hills toward the northern part of Yucca Mountain; (2) thickening of the Prow Pass Member but thinning of the Bullfrog Member and Tram unit; (3) thinning of the tuff of Lithic Ridge; (4) presence of approximately 280 m of lava and flow breccia not previously penetrated by any drill hole; and (5) presence of an ash-flow tuff unit at the bottom of the drill hole not previously intersected, apparently the oldest unit penetrated at Yucca Mountain to date. Petrographic features of some of the units include: (1) decrease in quartz and K-feldspar and increases in biotite and plagioclase with depth in the tuffaceous beds of Calico Hills; (2) an increase in quartz phenocrysts from the top to the bottom members of the Crater Flat Tuff; (3) a low quartz content in the tuff of Lithic Ridge, suggesting tapping of the magma chamber at quartz-poor levels; (4) a change in zeolitic alteration from heulandite to clinoptilolite to mordenite with increasing depth; (5) lavas characterized by a rhyolitic

  20. Colloid-Facilitated Transport of Low-Solubility Radionuclides: A Field, Experimental, and Modeling Investigation

    SciTech Connect

    Kersting, A B; Reimus, P W; Abdel-Fattah, A; Allen, P G; Anghel, I; Benedict, F C; Esser, B K; Lu, N; Kung, K S; Nelson, J; Neu, M P; Reilly, S D; Smith, D K; Sylwester, E R; Wang, L; Ware, S D; Warren, RG; Williams, R W; Zavarin, M; Zhao, P

    2003-02-01

    For the last several years, the Underground Test Area (UGTA) program has funded a series of studies carried out by scientists to investigate the role of colloids in facilitating the transport of low-solubility radionuclides in groundwater, specifically plutonium (Pu). Although the studies were carried out independently, the overarching goals of these studies has been to determine if colloids in groundwater at the NTS can and will transport low-solubility radionuclides such as Pu, define the geochemical mechanisms under which this may or may not occur, determine the hydrologic parameters that may or may not enhance transport through fractures and provide recommendations for incorporating this information into future modeling efforts. The initial motivation for this work came from the observation in 1997 and 1998 by scientists from Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL) that low levels of Pu originally from the Benham underground nuclear test were detected in groundwater from two different aquifers collected from wells 1.3 km downgradient (Kersting et al., 1999). Greater than 90% of the Pu and other radionuclides were associated with the naturally occurring colloidal fraction (< 1 micron particles) in the groundwater. The colloids consisted mainly of zeolite (mordenite, clinoptilolite/heulandite), clays (illite, smectite) and cristobalite (SiO{sub 2}). These minerals were also identified as alteration mineral components in the host rock aquifer, a rhyolitic tuff. The observation that Pu can and has migrated in the subsurface at the NTS has forced a rethinking of our basic assumptions regarding the mechanical and geochemical transport pathways of low-solubility radionuclides. If colloid-facilitated transport is the primary mechanism for transporting low-solubility radionuclides in the subsurface, then current transport models based solely on solubility arguments and retardation estimates may underestimate the flux and

  1. Tephra Deposits in Lake Mead Miocene Sediments: Characteristics, Chronology, and Sources

    NASA Astrophysics Data System (ADS)

    Dunbar, N. W.; McIntosh, W. C.; Umhoefer, P. J.; Lamb, M. A.; Hickson, T.

    2013-12-01

    The Lake Mead extensional domain, in the east central Basin and Range Province, contains Miocene basin sediments that have undergone complex faulting and deformation. A rich tephra record in the basin sediments provides a chronological and correlation framework that can help understand the depositional and deformational processes during Miocene and post-Miocene time. The tephra layers, up to 10s of cm thick, range from white deposits containing glassy shards to bright green layers in which all original glass has been altered to the zeolite mordenite. The tephra layers range from aphyric to extremely crystal rich. Many appear to be primary ashfall deposits based on depositional geometry, uniform crystal size, and good preservation of glass or relict glass shard structures. However, some layers show evidence of reworking as evidenced by variable crystal size, and the presence of plutonic feldspar and rock fragments. Electron microprobe analyses of preserved glass reveal that compositions of almost all of the tephra layers are high silica rhyolite, typically with FeO and CaO contents of 1wt% or lower. Where present, the glass in the tephra layers is invariably hydrated, consistent with their age, but although the alkali concentrations in the glass are likely to have been modified by the hydration process, other elements, particularly Fe, Ca, Ti, and Cl appear to yield robust concentrations. The compositions of individual layers with respect to these elements are very homogeneous, based on analysis of 20-30 glass shards per sample, and can be used to correlate individual tephra layers between different parts of the sedimentary basin, although a number of layers have very similar compositions. Some higher Fe rhyolites/dacites (up to 4 wt.% FeO) are also observed. Crystal-bearing tephra layers contain some combination of quartz, one or two feldspars (typically a chemically uniform sanidine and a range of plagioclase compositions), biotite, amphibole, and magnetite

  2. Geothermometry, geochronology, and mass transfer associated with hydrothermal alteration of a rhyolitic hyaloclastite from Ponza Island, Italy

    NASA Astrophysics Data System (ADS)

    Altaner, Stephen P.; Ylagan, Robert F.; Savin, Samuel M.; Aronson, James L.; Belkin, Harvey E.; Pozzuoli, Antonio

    2003-01-01

    A rhyolitic hyaloclastite from Ponza Island, Italy, was hydrothermally altered, producing four distinct alteration zones based on X-ray diffraction mineralogy and field textures: (1) nonpervasive argillic zone; (2) propylitic zone; (3) silicic zone; and (4) sericitic zone. The unaltered hyaloclastite is volcanic breccia with clasts of vesiculated obsidian in a matrix of predominantly pumice lapilli. Incomplete alteration of the hyaloclastite resulted in the nonpervasive argillic zone, characterized by smectite and disordered opal-CT. The other three zones exhibit more complete alteration of the hyaloclastite. The propylitic zone is characterized by mixed-layer illite-smectite (I-S) with 10 to 85% I, mordenite, opal-C, and authigenic K-feldspar (akspar). The silicic zone is characterized by I-S with ≥90% I, pure illite, quartz, akspar, and occasional albite. The sericitic zone consists primarily of I-S with ≥66% I, pure illite, quartz, and minor akspar and pyrite. K/Ar dates of I-S indicate hydrothermal alteration occurred at 3.38 ± 0.08 Ma. Oxygen isotope compositions of I-S systematically decrease from zones 1 to 4. In the argillic zone, smectite has δ 18O values of 21.7 to 22.0‰ and I-S from the propylitic, silicic, and sericitic zones ranges from 14.5 to 16.3‰, 12.5 to 14.0‰, and 8.6 to 11.9‰, respectively. δ 18O values for quartz from the silicic and sericitic zones range from 12.6 to 15.9‰. By use of isotope fractionation equations and data from authigenic quartz-hosted primary fluid inclusions, alteration temperatures ranged from 50 to 65°C for the argillic zone, 85 to 125°C for the propylitic zone, 110 to 210°C for the silicic zone, and 145 to 225°C for the sericitic zone. Fluid inclusion data and calculated δ 18O water values indicate that hydrothermal fluids were seawater dominated. Mass-transfer calculations indicate that hydrothermal alteration proceeded in a relatively open chemical system and alteration in the sericitic zone

  3. Identification of Some Zeolite Group Minerals by Application of Artificial Neural Network and Decision Tree Algorithm Based on SEM-EDS Data

    NASA Astrophysics Data System (ADS)

    Akkaş, Efe; Evren Çubukçu, H.; Akin, Lutfiye; Erkut, Volkan; Yurdakul, Yasin; Karayigit, Ali Ihsan

    2016-04-01

    Identification of zeolite group minerals is complicated due to their similar chemical formulas and habits. Although the morphologies of various zeolite crystals can be recognized under Scanning Electron Microscope (SEM), it is relatively more challenging and problematic process to identify zeolites using their mineral chemical data. SEMs integrated with energy dispersive X-ray spectrometers (EDS) provide fast and reliable chemical data of minerals. However, considering elemental similarities of characteristic chemical formulae of zeolite species (e.g. Clinoptilolite ((Na,K,Ca)2 ‑3Al3(Al,Si)2Si13O3612H2O) and Erionite ((Na2,K2,Ca)2Al4Si14O36ṡ15H2O)) EDS data alone does not seem to be sufficient for correct identification. Furthermore, the physical properties of the specimen (e.g. roughness, electrical conductivity) and the applied analytical conditions (e.g. accelerating voltage, beam current, spot size) of the SEM-EDS should be uniform in order to obtain reliable elemental results of minerals having high alkali (Na, K) and H2O (approx. %14-18) contents. This study which was funded by The Scientific and Technological Research Council of Turkey (TUBITAK Project No: 113Y439), aims to construct a database as large as possible for various zeolite minerals and to develop a general prediction model for the identification of zeolite minerals using SEM-EDS data. For this purpose, an artificial neural network and rule based decision tree algorithm were employed. Throughout the analyses, a total of 1850 chemical data were collected from four distinct zeolite species, (Clinoptilolite-Heulandite, Erionite, Analcime and Mordenite) observed in various rocks (e.g. coals, pyroclastics). In order to obtain a representative training data set for each minerals, a selection procedure for reference mineral analyses was applied. During the selection procedure, SEM based crystal morphology data, XRD spectra and re-calculated cationic distribution, obtained by EDS have been used for

  4. Closed Fuel Cycle Waste Treatment Strategy

    SciTech Connect

    Vienna, J. D.; Collins, E. D.; Crum, J. V.; Ebert, W. L.; Frank, S. M.; Garn, T. G.; Gombert, D.; Jones, R.; Jubin, R. T.; Maio, V. C.; Marra, J. C.; Matyas, J.; Nenoff, T. M.; Riley, B. J.; Sevigny, G. J.; Soelberg, N. R.; Strachan, D. M.; Thallapally, P. K.; Westsik, J. H.

    2015-02-01

    This study is aimed at evaluating the existing waste management approaches for nuclear fuel cycle facilities in comparison to the objectives of implementing an advanced fuel cycle in the U.S. under current legal, regulatory, and logistical constructs. The study begins with the Global Nuclear Energy Partnership (GNEP) Integrated Waste Management Strategy (IWMS) (Gombert et al. 2008) as a general strategy and associated Waste Treatment Baseline Study (WTBS) (Gombert et al. 2007). The tenets of the IWMS are equally valid to the current waste management study. However, the flowsheet details have changed significantly from those considered under GNEP. In addition, significant additional waste management technology development has occurred since the GNEP waste management studies were performed. This study updates the information found in the WTBS, summarizes the results of more recent technology development efforts, and describes waste management approaches as they apply to a representative full recycle reprocessing flowsheet. Many of the waste management technologies discussed also apply to other potential flowsheets that involve reprocessing. These applications are occasionally discussed where the data are more readily available. The report summarizes the waste arising from aqueous reprocessing of a typical light-water reactor (LWR) fuel to separate actinides for use in fabricating metal sodium fast reactor (SFR) fuel and from electrochemical reprocessing of the metal SFR fuel to separate actinides for recycle back into the SFR in the form of metal fuel. The primary streams considered and the recommended waste forms include; Tritium in low-water cement in high integrity containers (HICs); Iodine-129: As a reference case, a glass composite material (GCM) formed by the encapsulation of the silver Mordenite (AgZ) getter material in a low-temperature glass is assumed. A number of alternatives with distinct advantages are also considered including a fused silica waste form

  5. Erionite and other fibrous zeolites in volcanic environments: the need for a risk assessment in Italy

    NASA Astrophysics Data System (ADS)

    Cavallo, A.; Rimoldi, B.

    2012-04-01

    In many European countries in the '90s there was a significant increase in mortality linked to mesothelioma, a cancer of the lung, involving pleural, pericardial and peritoneal mesothelial cells, which unfortunately has no cure at present. Though most of these cases have been attributed to t asbestos, in Italy at least 17% of cases of mesothelioma is still not fully explained. In the years between 1990 and 2000, it was discovered that the inhalation of erionite fibers (a zeolite group mineral, that can be found in altered volcanic rocks) was the cause of a regional epidemic of mesothelioma in some villages of Cappadocia (Turkey). Erionite, in fact, was recently included in Class 1 (highly carcinogenic) by the World Health Organization, up to 800 times more carcinogenic than asbestos; on the other hand, little is known about the toxicity of other fibrous zeolites, commonly intergrown with erionite, such as offretite and mordenite. Erionite was reported in different regions of Italy; nevertheless, a systematic mapping of its distribution, the quantification of its presence in rocks and data about airborne fibers are still missing. We carried out first preliminary sampling in Veneto, in Tertiary volcanic rocks, mainly hydrothermally altered basalts. The first mineralogical investigations by means of XRPD, SEM-EDS and OM confirmed the presence of small amounts of erionite and abundant fibrous offretite, in vugs of basaltic rocks. Intergrowths and overgrowths with other fibrous minerals are quite common, and the morphological-chemical similarities among these zeolites pose a special analytical problem, with the need of combining different techniques. Our first findings, combined with the fact that zeolites are important industrial minerals, emphasize the need of a risk assessment in Italy and Europe, because there are no systematic studies on the distribution of erionite or similar fibrous zeolites in the environment. The knowledge of the epidemiology of mesothelioma

  6. Internal load management in eutrophic, anoxic environments. The role of natural zeolite.

    NASA Astrophysics Data System (ADS)

    Gianni, Areti; Zacharias, Ierotheos

    2015-04-01

    During the last decades, the increase of the nutrient and organic load inflows in the coastal zone increased the number of the anoxic environments. Inputs' control constitutes one of the basic practices for the eutrophic/anoxic aquatic ecosystems management. However, the induced changes at the ecosystem characteristics resulting from the trophic state alteration, and anoxic conditions prevalence, render the ecosystem's restoration difficult if not impossible. Bottom water anoxia accelerates PO43-, NH4+ and S2- recycling and accumulation from organic matter decomposition. This, toxic layer is a permanent menace for the balance of the entire ecosystem, as it can supply PO43-, NH4+ and S2- to the surface layers altering their qualitative character and threatening the welfare of fishes and other aquatic organisms. Having as objective the water basins' internal load control and based on practices are used in eutrophic environments' restoration, this study is referred to the role of the natural zeolite in eutrophic/anoxic ecosystems management. For the first time are presented, results from S2- removal experiments using the zeolitic mineral mordenite, [(Na2, Ca, K2)4 (H2O)28] [Al8Si40O96]. Four different sets of experiments were conducted, in order to examine zeolite's removal capacity of S2- in aquatic solutions, under a wide range of physicochemical parameters. More specific: a) the effect of initial pH on the removal process, b) the removal process kinetics, c) the removal process isotherms and d) the effect of salinity on the removal process were studied. Natural zeolite has the ability to neutralize the pH of aqueous solutions, thus all the experiments were practically performed at pH 7. Initially sulfides concentration range from 1 to 10mg/l. Zeolite's removal capability appeared to be directly depended on the S2- initial concentration. For initial concentration of 1mg/l, the removal rate reached up to 90% after 24h. The maximum zeolite removal capacity was

  7. Milestone Report - M3FT-15OR03120211 - Complete Iodine Loading of NO Aged Ag0-functionalized Aerogel

    SciTech Connect

    Bruffey, Stephanie H.; Patton, Kaara K.; Jubin, Robert Thomas

    2015-05-29

    In off-gas treatment systems within a nuclear fuel reprocessing plant, capture materials will be exposed to a gas stream for extended periods during their lifetime. This gas stream may be at elevated temperature and could contain water, NOx gas, or a variety of other constituents. For this reason, it is important to understand the effects of long-term exposure, or aging, on proposed capture materials. One material under consideration for iodine sequestration is silver-functionalized silica aerogel (Ag0-aerogel). The aim of this study was to determine the effect of extended exposure at 150°C to an air stream containing NO on the iodine capture capacity of Ag0-aerogel. Ag0-aerogel was provided by the Pacific Northwest National Laboratory (PNNL), which manufactures the material at a lab scale. Prior to aging, the material has an iodine loading capacity of approximately 290 mg I/g Ag0-aerogel. Previous studies have aged the material in a dry air stream or in a moist air stream for up to 6 months. Both tests resulted in a 22% loss in iodine capacity. Aging the material in a static 2% NO2 environment for up to 2 months results in a 15% loss of iodine capacity.3 In this study, exposure of Ag0-aerogel to 1% NO at 150°C for 2 months produced a loss of 43% in iodine loading capacity. This is largest loss observed for aerogel aging studies to date. The performance of Ag0-aerogel in this study was compared to the performance of reduced silver mordenite (Ag0Z) in similar studies. Ag0Z is a zeolite mineral considered to be the current standard technology for iodine removal from off-gas streams of a potential US used fuel processing plant. In an aging study exposing Ag0Z to 1% NO for 2 months, an iodine capacity loss of over 80% was observed. This corresponds to a silver utilization of 13.5% for 2 month NO-aged Ag0Z, compared to 57% silver utilization for 2

  8. Hanford Site Secondary Waste Roadmap

    SciTech Connect

    Westsik, Joseph H.

    2009-01-29

    Summary The U.S. Department of Energy (DOE) is making plans to dispose of 54 million gallons of radioactive tank wastes at the Hanford Site near Richland, Washington. The high-level wastes and low-activity wastes will be vitrified and placed in permanent disposal sites. Processing of the tank wastes will generate secondary wastes, including routine solid wastes and liquid process effluents, and these need to be processed and disposed of also. The Department of Energy Office of Waste Processing sponsored a meeting to develop a roadmap to outline the steps necessary to design the secondary waste forms. Representatives from DOE, the U.S. Environmental Protection Agency, the Washington State Department of Ecology, the Oregon Department of Energy, Nuclear Regulatory Commission, technical experts from the DOE national laboratories, academia, and private consultants convened in Richland, Washington, during the week of July 21-23, 2008, to participate in a workshop to identify the risks and uncertainties associated with the treatment and disposal of the secondary wastes and to develop a roadmap for addressing those risks and uncertainties. This report describes the results of the roadmap meeting in Richland. Processing of the tank wastes will generate secondary wastes, including routine solid wastes and liquid process effluents. The secondary waste roadmap workshop focused on the waste streams that contained the largest fractions of the 129I and 99Tc that the Integrated Disposal Facility risk assessment analyses were showing to have the largest contribution to the estimated IDF disposal impacts to groundwater. Thus, the roadmapping effort was to focus on the scrubber/off-gas treatment liquids with 99Tc to be sent to the Effluent Treatment Facility for treatment and solidification and the silver mordenite and carbon beds with the captured 129I to be packaged and sent to the IDF. At the highest level, the secondary waste roadmap includes elements addressing regulatory and

  9. Impact Materials of Takamatsu Crater in Japan

    NASA Astrophysics Data System (ADS)

    Miura, Y.; Okamoto, M.; Fukuchi, T.

    1995-09-01

    Shocked quartz materials have been found in Japanese K.T boundary (Hokkaido) and mountains of middle main-islands of Japan, though there are few direct evidence of "natural circular structure" on the surface in Japan. However circular structure has been recently found as a buried crater(up to 150m deep) [1] which is ca. 4km in diameter with -10 mgal of Bouguer gravity anomaly from surrounding Rhyoke granitic region of the southern part of Takamatsu City, Kagawa Prefecture, northeast Shikoku, Japan [1,2,3]. Two boring cores of 300m deep near small mountains inside the crater could not reach the bottom of the crater so far. From model calculation of the negative gravity anomaly, the Takamatsu crater shows deep basin structure up to 1.4km. If the Takamatsu crater is considered to be only impact crater, it is difficult to discuss only surface materials on the crater. But anomalous minerals are found only around small volcanic intrusions inside the crater, which the mixed minerals are clearly different with those of other volcanic intrusions of the Yashima and Goshikidai outside the crater [1,2,3]. The small volcanic intrusions are not origin of large Takamatsu crater, because the small volcanic intrusions are found on whole areas of Kagawa Prefecture. Major different activity of the small intrusions inside the crater is to bring the brecciated materials of the interior (esp. crater sediments). The xenolith materials around only volcanic intrusion of andesite are divided into the following four major mineral materials:(a) round pebble fragments from the Rhyoke granitic basement (Sampling No.15), (b) rock fragments from intruded biotite andesites (Nos. 2,15), (c) impact-induced fragments of shocked Quartz grains (Nos. 2,3,6,15), diaplectic feldspars (Nos. 2,3,6,15), silica glasses (Nos. 2,15) and small Fe-Ni metallic grains (No.15), and (d) small sedimentary fragments of halite and mordenite, as listed in Table 1. Table I, showing the characterization of surface samples

  10. Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite.

    PubMed

    Elmore, Amy R

    2003-01-01

    This report reviews the safety of Aluminum, Calcium, Lithium Magnesium, Lithium Magnesium Sodium, Magnesium Aluminum, Magnesium, Sodium Magnesium, and Zirconium Silicates, Magnesium Trisilicate, Attapulgite, Bentonite, Fuller's Earth, Hectorite, Kaolin, Montmorillonite, Pyrophyllite, and Zeolite as used in cosmetic formulations. The common aspect of all these claylike ingredients is that they contain silicon, oxygen, and one or more metals. Many silicates occur naturally and are mined; yet others are produced synthetically. Typical cosmetic uses of silicates include abrasive, opacifying agent, viscosity-increasing agent, anticaking agent, emulsion stabilizer, binder, and suspending agent. Clay silicates (silicates containing water in their structure) primarily function as adsorbents, opacifiers, and viscosity-increasing agents. Pyrophyllite is also used as a colorant. The International Agency for Research on Cancer has ruled Attapulgite fibers >5 microm as possibly carcinogenic to humans, but fibers <5 microm were not classified as to their carcinogenicity to humans. Likewise, Clinoptilolite, Phillipsite, Mordenite, Nonfibrous Japanese Zeolite, and synthetic Zeolites were not classified as to their carcinogenicity to humans. These ingredients are not significantly toxic in oral acute or short-term oral or parenteral toxicity studies in animals. Inhalation toxicity, however, is readily demonstrated in animals. Particle size, fibrogenicity, concentration, and mineral composition had the greatest effect on toxicity. Larger particle size and longer and wider fibers cause more adverse effects. Magnesium Aluminum Silicate was a weak primary skin irritant in rabbits and had no cumulative skin irritation in guinea pigs. No gross effects were reported in any of these studies. Sodium Magnesium Silicate had no primary skin irritation in rabbits and had no cumulative skin irritation in guinea pigs. Hectorite was nonirritating to the skin of rabbits in a Draize primary skin

  11. Impact Materials of Takamatsu Crater in Japan

    NASA Astrophysics Data System (ADS)

    Miura, Y.; Okamoto, M.; Fukuchi, T.

    1995-09-01

    Shocked quartz materials have been found in Japanese K.T boundary (Hokkaido) and mountains of middle main-islands of Japan, though there are few direct evidence of "natural circular structure" on the surface in Japan. However circular structure has been recently found as a buried crater(up to 150m deep) [1] which is ca. 4km in diameter with -10 mgal of Bouguer gravity anomaly from surrounding Rhyoke granitic region of the southern part of Takamatsu City, Kagawa Prefecture, northeast Shikoku, Japan [1,2,3]. Two boring cores of 300m deep near small mountains inside the crater could not reach the bottom of the crater so far. From model calculation of the negative gravity anomaly, the Takamatsu crater shows deep basin structure up to 1.4km. If the Takamatsu crater is considered to be only impact crater, it is difficult to discuss only surface materials on the crater. But anomalous minerals are found only around small volcanic intrusions inside the crater, which the mixed minerals are clearly different with those of other volcanic intrusions of the Yashima and Goshikidai outside the crater [1,2,3]. The small volcanic intrusions are not origin of large Takamatsu crater, because the small volcanic intrusions are found on whole areas of Kagawa Prefecture. Major different activity of the small intrusions inside the crater is to bring the brecciated materials of the interior (esp. crater sediments). The xenolith materials around only volcanic intrusion of andesite are divided into the following four major mineral materials:(a) round pebble fragments from the Rhyoke granitic basement (Sampling No.15), (b) rock fragments from intruded biotite andesites (Nos. 2,15), (c) impact-induced fragments of shocked Quartz grains (Nos. 2,3,6,15), diaplectic feldspars (Nos. 2,3,6,15), silica glasses (Nos. 2,15) and small Fe-Ni metallic grains (No.15), and (d) small sedimentary fragments of halite and mordenite, as listed in Table 1. Table I, showing the characterization of surface samples