Sample records for mordenite

  1. Acid site promotion of mordenite

    Microsoft Academic Search

    W. J. Kiovsky; J. R. Goyette; T. M. Notermann


    Ammonia adsorption isotherms for H-mordenite (10:1 silica-alumina) and partially dealuminated H-mordenite (13:1 silica-alumina) showed that dealumination generated new strong acid sites, in contrast to dealumination of Y-zeolite, which decreases first the weak and then the stronger acid sites. An IR spectroscopic study of 13:1 and 16:1 silica-alumina mordenites showed that the number of both Lewis and Broensted strong acid sites

  2. Methyl iodide sorption by reduced silver mordenite

    SciTech Connect

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


    At the Pacific Northwest Laboratory (PNL), we performed two sets of experiments to determine the effects of pertinent operational parameters and gas compositions on organic radioiodine (in particular methyl iodide (CH/sub 3/I)) capture by silver mordenite (AgZ). In the first set of experiments, we studied the effects of (1) hydrogen pretreatment of AgZ, (2) change in particle size of AgZ, and (3) the presence of water in the gas phase. In the second set of experiments we evaluated on a semi-quantitative basis the effects of nitric oxide (NO), nitrogen dioxide (NO/sub 2/), superficial face velocity, and temperature on CH/sub 3/I capture by reduced (hydrogen pretreated) silver mordenite (Ag/sup 0/Z). These studies have shown that AgZ, especially Ag/sup 0/Z, is an effective trap for CH/sub 3/I. However, its effectiveness varies with changes in operational parameters and is affected by other gases found in the process off gas of a nuclear reprocessing plant. Optimum trappig efficiency was achieved with Ag/sup 0/Z rather than AgZ, 20-40 mesh Ag/sup 0/Z rather than 0.16 cm extrudate, moisture in the gas stream, higher temperatures up to 200/sup 0/C, absence of NO, and lower superficial face velocities down to 3.75 m/min. Additionally, CH/sub 3/I can be converted to elemental iodine (I/sub 2/) in the presence of NO or NO/sub 2/ by controlling the operational parameters. Since I/sub 2/ is easier to trap than organic iodides, this should improve trapping efficiency,.

  3. Preparation of highly accessible mordenite coatings on ceramic monoliths at loadings exceeding 50% by weight.


    Ulla, M A; Miro, E; Mallada, R; Coronas, J; Santamaria, J


    A mordenite layer with a high accessibility has been synthesised on cordierite monolith supports; substantial loadings of mordenite were achieved (above 50 wt%) under the synthesis conditions used. PMID:14973591

  4. Desulfurization of FCC Gasoline Over Mordenite Modified with Al2O3

    Microsoft Academic Search

    Hong-yu Jiao; Li-na Yang; Jian Shen; Jian Li; Yu-tai Qi


    Mordenite modified with Al2O3 (Al2O3\\/mordenite) was synthesized and used for the desulfurization of FCC gasoline. The influences of operating parameters on the results were studied for the model solution composed of dibenzothiophene (DBT) and isooctane. Al2O3\\/mordenite exhibits higher sulfur capacity than other kinds of chemisorbents. The suitable composition of the chemisorbent is 30 wt% Al2O3 to 70 wt% mordenite. The

  5. Sorption of HDTMA cations on Croatian natural mordenite tuff.


    Roži?, Mirela; Miljani?, Snežana


    Sorption of the cationic surfactant, hexadecyltrimethylammonium cations (HDTMA), on the solid/liquid interface of the natural mordenite tuff (MT) was studied. The examined tuff originated from Croatia consisting of 30% of mordenite. SEM observations confirmed the crystalline nature of mordenite which can be described in terms of aggregates of many small platelets with diameters in the range of 1 ?m. Studying the porosity properties of MT, it was found that the average pore diameter (4.42 nm) between mordenite's platelets allows penetration of HDTMA cations. The measurements of zeta potential indicated that in MT samples with surfactant concentration in the range between 0.013 and 0.25 mmol/g, HDTMA cations fill the mesopores of MT. By further increase in HDTMA concentration, the surfactant sorbs on the external zeolite surface, as revealed by the SEM micrographs. Vibrational (FTIR and FT Raman) spectra showed that in the MT samples with initial HDTMA concentration from 0.013 to 0.25 mmol/g, alkyl chains adopt mainly gauche conformation, whereas in the MT samples with higher initial HDTMA concentrations trans conformers are predominant and form a highly ordered structure on the mordenite surface. PMID:20940081

  6. Catalytic polymerization of N,N-diethanol acrylamide with phthalic anhydride in the presence of H-mordenite and Fe-mordenite zeolites

    Microsoft Academic Search

    Mohamed Mokhtar Mohamed; F Abd El-Hai


    The H-mordenite zeolite catalyzes the polymerization of N,N-diethanol acrylamide (DEAA) with phthalic anhydride (PA) yielding polyesteramide (PEA) resin. The Fe modified mordenites showed lower activity than that of H-mordenite that presented high stability on multiple recycling. The formation of DEAA; the principal step in forming PEA, was occurred through the condensation reaction of diethanol amine (DEA) and acrylic acid (AA)

  7. On the influence of the mordenite acidity in the hydroconversion of linear alkanes over Pt-mordenite catalysts

    Microsoft Academic Search

    Luis Oswaldo Almanza; Thomas Narbeshuber; Paolo d'Araujo; Claude Naccache; Younès Ben Taarit


    Hydroconversion of n-octane and n-hexane was investigated on a series of platinum loaded mordenite samples with varied framework aluminium (FAl) content. In agreement with previous authors, it was observed that the rate of hydroconversion is first increased almost linearly with the number of FAl per unit cell, reached a maximum then decreased abruptly as the number of the FAl\\/unit cell

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

    SciTech Connect

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


    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.

  9. Sorption of Sulfur Dioxide on Hydrogen Form and Aluminum-Deficient Mordenites

    Microsoft Academic Search

    Suzan Kincal; Ali Çulfaz


    The SO2 sorption characteristics of a commercial H-mordenite and an aluminum-deficient mordenite with a molar SiO2\\/Al2O3 ratio of 75, prepared from the H-form, were investigated. The sorption isotherms and the reduced sorptive diffusivities were determined in the temperature range 298–358 K and at pressures up to 0.2 atm. It was found that the partially irreversible SO2 sorption on the H-form

  10. The effect of iron on the biological activities of erionite and mordenite.


    Fach, Estelle; Kristovich, Robert; Long, John F; Waldman, W James; Dutta, Prabir K; Williams, Marshall V


    Epidemiological data has demonstrated that environmental and/or occupational exposure to mineral particulates may result in the development of pulmonary fibrosis, bronchogenic carcinoma and malignant mesothelioma many years following exposure. It has been suggested that the genotoxic effects of fibrous particulates, such as asbestos, is due in part to the generation of reactive oxygen species (ROS) from iron associated with the particulates. However, the molecular mechanisms by which mineral particulates induce ROS that results in genotoxic damage remains unclear. The naturally occurring zeolites, erionite and mordenite share several physiochemical properties but they elicit very different biological responses, with erionite, a fibrous particulate, being highly toxic, and mordenite, a nonfibrous particulate, being relatively benign. We are using these natural zeolites as a model system to determine what physicochemical properties of these zeolites are responsible for their biological response(s) and to evaluate the parameters that influence these responses. The purpose of the present study was to determine the mutagenic potential of erionite and mordenite and to determine whether this mutagenic potential was modulated by iron. The results of this study using the Chinese hamster ovary cell line AS52 demonstrated that erionite was more cytotoxic than mordenite. However, the cytotoxicity of both zeolites was increased in the presence of physiological concentrations of ferrous chloride. Ferrous ions (5-20 microM) significantly (p<0.001) increased the cytotoxicity of mordenite, but only at the highest concentration (16 microg/cm(2)) of mordenite tested. Conversely, only the highest concentration (20 microM) of ferrous ion significantly (p<0.001) increased the cytotoxicity of erionite, but this enhanced cytotoxicity occurred over a wider concentration range (6-16 microg/cm(2)) of erionite. Mordenite was not mutagenic at any of the concentrations tested, and the mutagenic potential of mordenite was not enhanced by the addition of ferrous ion. Conversely, erionite was mutagenic in a dose-response manner at concentrations greater than 6 microg/cm(2) and the mutagenic potential of erionite was significantly enhanced by the addition of ferrous ions. These results suggest that while the cytotoxicity of mordenite and erionite may be related to the ability of these fibers to transport iron into a cell, the different coordination state of iron associated with the two fiber surfaces is critical for inducing genotoxic damage. PMID:12705942

  11. 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.


    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

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


    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


    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

  13. Improving the stability of H-mordenite for n-butane isomerization

    SciTech Connect

    Asuquo, R.A.; Eder-Mirth, G.; Lercher, J.A. [Catalysis Univ. of Twente, Enschede (Netherlands)] [and others] [Catalysis Univ. of Twente, Enschede (Netherlands); and others


    The conversion of n-butane over mordenite-based catalysts in the presence of hydrogen and water was investigated for reaction temperatures between 523 and 623 K. Special attention was given to the influence of Pt upon catalytic activity, selectivity, and stability. With parent mordenite the catalytic activity for n-butane conversion decreased markedly after a short time on stream. Deactivation can be minimized by hydrogen (in the presence of Pt) and water addition. Both measures are thought to reduce the concentration of intermediate olefins in the zeolite pores. The best results with respect to selective conversion of n-butane to isobutane were obtained for 0.25 wt% Pt on mordenite in the presence of hydrogen. Higher concentrations of Pt in the catalyst are shown to be detrimental for n-butane isomerization, because of increasing selectivity to hydrogenolysis. A detailed mechanistic scheme for n-butane conversion over Pt-containing mordenites is presented. n-Butane conversion is concluded to occur via a bimolecular mechanism involving a complex network of hydrogen transfer, oligomerization/cracking, isomerization, hydrogenation/dehydrogenation, and hydrogenolysis. 23 refs., 14 figs., 5 tabs.

  14. Hydrothermally synthesized high silica mordenite as an efficient catalyst in alkylation reaction under liquid phase condition

    Microsoft Academic Search

    Sujit Samanta; Nawal Kishor Mal; Prashant Kumar; Asim Bhaumik


    High silica mordenite (HSM) samples have been synthesized hydrothermally by using low aluminum contents (Si\\/Al molar ratios 40 and 60) with the synthesis gel in the presence of orthophosphoric acid as promoter at 443K. Sodium silicate and aluminum sulfate were used as Si and Al precursors, respectively. Solid yield and particle size of these materials have been improved considerably over

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


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


    Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2 CO) 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 (CH2 DCOOD), when D2 O is introduced in the feed during the carbonylation reaction. PMID:25967363

  16. Optimization of lead adsorption of mordenite by response surface methodology: characterization and modification

    PubMed Central


    Background In order to remove heavy metals, water treatment by adsorption of zeolite is gaining momentum due to low cost and good performance. In this research, the natural mordenite was used as an adsorbent to remove lead ions in an aqueous solution. Methods The effects of adsorption temperature, time and initial concentration of lead on the adsorption yield were investigated. Response surface methodology based on Box-Behnken design was applied for optimization. Adsorption data were analyzed by isotherm models. The process was investigated by batch experiments; kinetic and thermodynamic studies were carried out. Adsorption yields of natural and hexadecyltrimethylammonium-bromide-modified mordenite were compared. Results The optimum conditions of maximum adsorption (nearly 84 percent) were found as follows: adsorption time of 85-90 min, adsorption temperature of 50°C, and initial lead concentration of 10 mg/L. At the same optimum conditions, modification of mordenite produced 97 percent adsorption yield. The most appropriate isotherm for the process was the Freundlich. Adsorption rate was found as 4.4. Thermodynamic calculations showed that the adsorption was a spontaneous and an exothermic process. Conclusions Quadratic model and reduced cubic model were developed to correlate the variables with the adsorption yield of mordenite. From the analysis of variance, the most influential factor was identified as initial lead concentration. At the optimum conditions modification increased the adsorption yield up to nearly 100 percent. Mordenite was found an applicable adsorbent for lead ions especially in dilute solutions and may also be applicable in more concentrated ones with lower yields. PMID:24393442

  17. Coke deactivation of Pd\\/H-mordenite catalysts used for C 5\\/C 6 hydroisomerization

    Microsoft Academic Search

    C. L. Li; O. Novaro; E. Muñoz; J. L. Boldú; X. Bokhimi; J. A. Wang; T. López; R. Gómez


    Coke formation in C5\\/C6 alkane isomerization on a Pd\\/H-Mordenite catalyst discharged from a pilot reactor was studied. Experimental techniques like XRD, EPR, MAS-NMR, FTIR, TGA and TPO, were applied for the characterization of coke and coked catalysts. It was shown that coke content, chemical composition, its structure and nature depended upon time-on-stream and section of the catalyst bed. The coke

  18. Adsorption Characteristics of Natural Erionite, Clinoptilolite and Mordenite Zeolites from Mexico

    Microsoft Academic Search

    M. A. Hernáandez; L. Corona; F. Rojas


    Nitrogen sorption properties inherent to some natural zeolites from Mexico, such as erionites, clinoptilolites and mordenites, are determined and compared with corresponding sorption properties of homologous synthetic or acid modified forms. The mineralogies of natural zeolites are determined by X-ray analysis. N2 low-pressure hysteresis loops are displayed by some substrata while are absent in others; key factors for this phenomenon

  19. 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. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185-1411 (United States)


    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)

  20. Interaction of mordenite with an aromatic hydrocarbon: An embedded ONIOM study

    Microsoft Academic Search

    Bavornpon Jansang; Tanin Nanok; Jumras Limtrakul


    The structure of mordenite (MOR) and its interaction with benzene has been investigated within the framework of our-own-N-layered integrated molecular orbital+molecular mechanics (ONIOM) approach utilizing the two-layer ONIOM scheme (B3LYP\\/6-31G(d,p):UFF). The effect of the long range interactions is also included via optimized point charges added to the ONIOM2(B3LYP\\/6-31G(d,p):UFF), embedded ONIOM. Inclusion of the extended zeolitic framework covering the nanocavity has

  1. Removal of free fatty acid in Azadirachta indica (Neem) seed oil using phosphoric acid modified mordenite for biodiesel production.


    SathyaSelvabala, Vasanthakumar; Varathachary, Thiruvengadaravi Kadathur; Selvaraj, Dinesh Kirupha; Ponnusamy, Vijayalakshmi; Subramanian, Sivanesan


    In this study free fatty acids present in Azadirachta indica (Neem) oil were esterified with our synthesized phosphoric acid modified catalyst. During the esterification, the acid value was reduced from 24.4 to 1.8 mg KOH/g oil. Synthesized catalyst was characterized by NH(3) TPD, XRD, SEM, FTIR and TGA analysis. During phosphoric acid modification hydrophobic character and weak acid sites of the mordenite were increased, which lead to better esterification when compared to H-mordenite. A kinetic study demonstrates that the esterification reaction followed pseudo-first order kinetics. Thermodynamic studies were also done based on the Arrhenius model. PMID:20346652

  2. Binary adsorption of very low concentration ethylene and water vapor on mordenites and desorption by microwave heating

    Microsoft Academic Search

    Seong-Ick Kim; Takashi Aida; Hiroo Niiyama


    Microwave heating can be applied to regeneration of an adsorbent in the removal of volatile organic compounds in very low concentration. In this study, binary adsorption of ethylene and water vapor on mordenites (MORs) was carried out for very low concentration of ethylene. Microwave was irradiated to the adsorbent bed and the effect of adsorbed water on the heating of

  3. A study involving mordenite, titanate nanotubes, perfluoroalkoxy polymers, and ammonia borane

    NASA Astrophysics Data System (ADS)

    Nosheen, Shaneela

    Zeolites and molecular sieves are finding applications in many areas of catalysis due to appreciable acid activity, shape selectivity, and ion-exchange capacity, as they possess an unbalanced framework charge. For catalytic applications, zeolites become more valuable as the ratio of SiO2/Al2O 3 increases. Acid resistance and thermal stability of zeolite are both improved with increasing SiO2/Al2O3. This part of the thesis deals with the control of morphology focused on decreasing the crystal diameter of mordenite zeolite and to increase the SiO2/Al 2O3 ratio by changing synthesis conditions. A high SiO 2/Al2O3 ratio (SAR15) of mordenite was prepared in a very short reaction time. We studied the role of hydroxide in the crystallization of the mordenite as a structure director, nucleation time modifier, and crystallite aggregate enhancer. The formation of nano-aggregates of mordenites was greatly enhanced using a combination of alcohol additives and conventional heating. Mordenite nucleation was also increased without using alcohols when microwave heating was employed, but the alcohols further accelerated the nucleation process. The different heating techniques affected the morphology; microwave heating produced crystallites of ˜40 nm, while the conventional hydrothermal method formed larger size crystallites of ˜88 nm. We controlled the size and shape of the mordenite crystals because they have important implications in hydrocarbon conversion and separation processes. Mordenite synthesized showed jellyfish, acicular, flower, and wheat grain like structures. In the second part of this thesis, a phase transition was successfully achieved from TiO2 particles to titanate nanotubes by the breakage of Ti-O bonds and the creation of oxygen vacancies without using expensive precursors, high temperatures, high chemical concentrations of alkaline solutions, and long synthesis times. A combination of anatase nano-particles/titanate nano-tubes was synthesized using TiO2 (anatase) and a temperature of only 100°C. When TiO2 (P-25) was used with the same concentration of alkaline solution (1 molar NaOH), the same processing time of 12 hours, and a higher temperature at 110°C, only titanate nano-tubes were observed. The linkages of 'Ti-O' play a very important role in the structural features of different phases. Two crystalline phases (tetragonal and monoclinic) were synthesized as products in the case of TiO 2 (anatase) and one crystalline phase (monoclinic) for products of TiO 2 (P-25). The third part of the thesis concerns surface modification of hydrophobic fluoropolymers that have low surface energies and are very difficult to metallize. Surface modification was done to enhance surface roughness and hence to boost surface energy for metallization processes. We used low impact, environmentally friendly non-thermal plasmas at atmospheric pressure to strip off F - ions and replace them with reactive unsaturated hydrocarbon functionalities such as CH=CH2 on the surface of a polymer. As these hydrocarbon functionalities are reactive with metals, they form composites that have good adhesion between layers of polymer. Due to surface modification, polymeric chains were broken by the loss of fluorine atoms (F/C = 0.33) and the gain of oxygen atoms (O/C = 0.17) using methane/argon plasmas. Methane/hydrogen/argon plasmas on the other hand produced extensive loss of fluorine atoms (F/C = 0.07-0.33) and gain of oxygen atoms (O/C = 0.08-0.16) that was far better than pristine PFA. The surface of PFA was modified by defluorination and oxidation. Further enhancement of COF and COO groups revealed that the surface was modified to a hydrophilic membrane that can further be easily hydrolyzed to COOH in the presence of atmospheric humidity. The last part of the thesis deals with ammonia borane which was studied as a potential source of hydrogen for fuel cells. We analyzed the viability of ammonia borane as a hydrogen carrier compound for fuel cell applications using a thermolysis method. Ammonia borane is an attractive source for hydrogen productio

  4. 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


    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.

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


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


    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


    SciTech Connect

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


    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.

  7. Stability of silver clusters in mordenites with different SiO 2\\/Al 2O 3 molar ratio

    Microsoft Academic Search

    Nina E Bogdanchikova; Vitalii P. Petranovskii; Roberto Machorro M; Yoshihiro Sugi; Victor M Soto G; Sergio Fuentes M


    The stability and decay of silver clusters characterized by absorption bands 320 and 285 nm incorporated in mordenites with different SiO2\\/Al2O3 molar ratios were studied under ambient conditions. Significantly different rates of disappearance of these two bands were the basis for assigning them to different silver species. Oxidation converts the clusters peaking at 320 and 285 nm into other silver

  8. An Explanation for the Enhanced Activity for Light Alkane Conversion in Mildly Steam Dealuminated Mordenite: The Dominant Role of Adsorption

    Microsoft Academic Search

    J. A. van Bokhoven; M. Tromp; D. C. Koningsberger; J. T. Miller; J. A. Z. Pieterse; J. A. Lercher; B. A. Williams; H. H. Kungx


    This paper presents a catalytic, spectroscopic, calorimetric study of mildly steam-dealuminated mordenite (H-MOR). With increasing steam partial pressures at 673 K there is increasing dealumination, the loss of Brønsted acid sites and the presence of extra-framework Al (AlEF) likely in the zeolite pores. Additionally, the number of Lewis sites increases with increasing AlEF. As observed in previous studies, the catalytic

  9. Catalytic properties of Fe ion-exchanged mordenite toward the ethanol transformation: influence of the methods of preparation

    Microsoft Academic Search

    Mohamed Mokhtar Mohamed


    The transformation of ethanol on Fe ion-exchanged mordenite was compared in the temperature range of 200–400°C for samples prepared in the solution and solid states. Ethane and methane were found as rather major products, compared to acetaldehyde and acetone. Diethyl ether was also detected as a dehydration product. The conversion was found to increase monotonically (to 96%) with increasing the

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

    SciTech Connect

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


    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 variations, and an expanded temperature range. Each sample was analyzed with the approach used in Phase I. In all cases, there is nothing in the SEM or XRD analyses that indicates creation of any AgI-containing silicon phase, with the samples being found to be largely amorphous. Phase III of this study has been initiated and is the final phase of scoping tests. It will expand upon the test matrix completed in Phase II and will examine the durability of the pressed pellets through product consistency testing (PCT) studies. Transformation of the component material into a well-characterized iodine-containing mineral phase would be desirable. This would limit the additional experimental testing and modeling required to determine the long-term stability of the pressed pellet, as much of that information has already been learned for several common iodine-containing minerals. However, this is not an absolute requirement, especially if pellets produced by hot isostatic pressing can be demonstrated through initial PCT studies to retain iodine well despite their amorphous composition.

  11. Methanol conversion on acidic ZSM-5, offretite, and mordenite zeolites: a comparative study of the formation and stability of coke deposits

    Microsoft Academic Search

    P. Dejaifve; A. Auroux; P. C. Gravelle; J. C. Vedrine; Z. Gabelica; E. G. Derouane


    The deposition of carbonaceous residues, leading to aging and modifications in the acidic properties of three zeolite samples differing by the size and shape of their interconnecting channel networks (ZSM-5, offretite, and mordenite), has been investigated during the conversion reaction of methanol to hydrocarbons. Catalytic tests, thermogravimetry, and microcalorimetry are used as complementary techniques. For zeolite ZSM-5, it is observed

  12. Hydrocarbon synthesis from methanol on erionite and mordenite catalysts synthesized in the presence of B 3+ , Ga 3+ or Fe 3+

    Microsoft Academic Search

    N. V. Klyueva; Nguen Duc Tien; K. G. Ione


    Selectivity of erionite and mordenite type aluminosilicates synthesized in the presence of B3+, Ga3+ or Fe3+ has been studied in methanol conversion to hydrocarbons. The olefin to paraffin ratio in the product is proportional to the Al2O3 content of the zeolites.

  13. Cerium impregnated H-mordenite as a catalyst for shape-selective isopropylation of naphthalene. Selective deactivation of acid sites on the external surface

    Microsoft Academic Search

    J.-H. Kim; Y. Sugi; T. Matsuzaki; T. Hanaoka; Y. Kubota; X. Tu; M. Matsumoto; S. Nakata; A. Kato; G. Seo; C. Pak


    The impregnation of cerium is the effective method for the deactivation of external acid sites of H-mordenite. The selectivity of 2,6-DIPN in the isopropylation of naphthalene was enhanced by the impregnation with such a large amount as 30–50 wt.-% of cerium without significant decrease of catalytic activity. The highest selectivity of 2,6-DIPN was achieved up to 70% over a highly

  14. Rationalizing inter- and intracrystal heterogeneities in dealuminated acid mordenite zeolites by stimulated Raman scattering microscopy correlated with super-resolution fluorescence microscopy.


    Liu, Kuan-Lin; Kubarev, Alexey V; Van Loon, Jordi; Uji-i, Hiroshi; De Vos, Dirk E; Hofkens, Johan; Roeffaers, Maarten B J


    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

  15. Adsorption capacity of hydrogen isotopes on mordenite

    Microsoft Academic Search

    Yoshinori Kawamura; Yoshihiro Onishi; Kenji Okuno; Toshihiko Yamanishi


    In a fusion reactor system, a monitoring of hydrogen isotopes including tritium is necessary for the safety of system control and operation. A gas chromatography using a cryogenic separation column is one of the methods for hydrogen isotope analysis. Synthesis zeolite such as molecular sieve 5A (CaA) is a candidate material of the separation column, and its property varies by

  16. The effect of iron on the biological activities of erionite and mordenite

    Microsoft Academic Search

    Estelle Fach; Robert Kristovich; John F. Long; W. James Waldman; Prabir K. Dutta; Marshall V. Williams


    Epidemiological data has demonstrated that environmental and\\/or occupational exposure to mineral particulates may result in the development of pulmonary fibrosis, bronchogenic carcinoma and malignant mesothelioma many years following exposure. It has been suggested that the genotoxic effects of fibrous particulates, such as asbestos, is due in part to the generation of reactive oxygen species (ROS) from iron associated with the

  17. Utilization of natural chabazite and mordenite as a reactive barrier for immobilization of hazardous heavy metals

    Microsoft Academic Search

    Ayman F. Seliman; Emad H. Borai

    Introduction  Understanding the sorption process in natural geomedia is necessary for effective utilization of these materials as low-cost\\u000a adsorbents and consequently as controlled release hazardous elements. This research was oriented to investigate the affinity\\u000a of two natural zeolite minerals towards cobalt, zinc, and nickel mixture as an important industrial and radioactive waste.\\u000a \\u000a \\u000a \\u000a \\u000a Method  The uptake of metal ions as a function of

  18. Removal of free fatty acid in Azadirachta indica (Neem) seed oil using phosphoric acid modified mordenite for biodiesel production

    Microsoft Academic Search

    Vasanthakumar SathyaSelvabala; Thiruvengadaravi Kadathur Varathachary; Dinesh Kirupha Selvaraj; Vijayalakshmi Ponnusamy; Sivanesan Subramanian


    In this study free fatty acids present in Azadirachta indica (Neem) oil were esterified with our synthesized phosphoric acid modified catalyst. During the esterification, the acid value was reduced from 24.4 to 1.8mg KOH\\/g oil. Synthesized catalyst was characterized by NH3 TPD, XRD, SEM, FTIR and TGA analysis. During phosphoric acid modification hydrophobic character and weak acid sites of the

  19. Structural investigations of zeolites ERS-7, mordenite, and sodalite using a combination of powder diffraction and computer simulation techniques

    Microsoft Academic Search

    Branton J. Campbell


    The framework structure of dehydrated template-free ERS-7 was determined by a combination of synchrotron X-ray powder diffraction and the simulated annealing approach of Deem and Newsam. The orthorhombic unit cell ( a = 9.79976(4) A, b = 12.41163(6) A, c = 22.86063(11) A) contains 6 tetrahedral framework atoms (Si\\/Al = 8.4), all on general positions, and 14 bridging oxygens. It

  20. Interaction between zeolites and cluster compounds. Part 1.?Adsorption of iron pentacarbonyl on zeolites

    Microsoft Academic Search

    Thomas Bein; Peter A. Jacobs


    Received 1 1 th November, 1982 The adsorption isotherms of Fe(CO), on Nay, HY and Linde L zeolites obtained in McBain balances show micropore adsorption, whereas additional capillary condensation is found with zeolite omega and Na-mordenite. The pores and\\/or cages of the zeolites studied are completely filled with the complex upon saturation, with the exception of Na-mordenite. Their behaviour is

  1. 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.


    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 ?-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.

  2. Fenten chemistry of Fe(III)-exchanged zeolitic minerals treated with antioxidants.


    Ruda, Toni A; Dutta, Prabir K


    Respirable mineral fibers, such as asbestos, are known to cause pleural mesothelioma, pulmonary fibrosis, and bronchial carcinoma, often years after exposure. Erionite and mordenite, two mineral aluminosilicates (zeolites) with different toxicities, can be used as models to help understand asbestos toxicity. Erionite is carcinogenic, while mordenite is relatively benign. No iron is typically present in erionite or mordenite, but because of their ion-exchange properties they can acquire iron after inhalation. The iron is typically in the Fe(III) form and will need to be reduced prior to any Fenton activity. Lung lining fluid contains antioxidants, such as glutathione (GSH) and ascorbic acid (AA), which can reduce Fe(III) to Fe(II). In this study, we have compared the Fenton reactivity of Fe(III)-exchanged erionite and mordenite after treatment with antioxidants. The Fenton assay involved the reaction of hydroxyl radicals with dimethyl sulfoxide. Fenton reactivity was most marked with AA followed by GSH, and hydrogen peroxide also exhibited minor reactivity. Erionite generated an order of magnitude greater hydroxyl radicals than mordenite, normalized to the surface iron content, providing support for the hypothesis that the iron coordination at the mineral surface plays a significant role in bioactivity. PMID:16173575

  3. Photodegradation of an azo dye using immobilized nanoparticles of TiO2 supported by natural porous mineral.


    Li, Fangfei; Sun, Shenmei; Jiang, Yinshan; Xia, Maosheng; Sun, Mengmeng; Xue, Bing


    Natural mordenite, replacing the synthetic zeolites, has been employed as the support of TiO2, and its photocatalytic activity has been examined in methyl orange (MO) aqueous under UV light. AFM, TEM, XRD, FTIR and fluorescence spectra have been used to reveal the loading effects of TiO2 on mordenite. The results show that the photocatalytic degradation (PCD) reaction rates are sharply increased by natural zeolite supports. Since mordenite is photo-inert, the PCD-enhancement is mostly caused by the bonding effects of Ti-O-Si and Ti-O-Al. Moreover, another two distinct natural zeolites have been employed as the supports of TiO2, in order to check the universality of PCD-enhancement effect of natural zeolites on TiO2. And the factors of PCD reaction on TiO2-zeolite, such as pH and catalyst dose, have been investigated. PMID:17869418

  4. Heats of adsorption of CO/sub 2/ and NH/sub 3/ on synthetic zeolites. communication 5. Adsorption of carbon dioxide on calcium zeolites

    SciTech Connect

    Zuerev, A.V.; Khvoshchev, S.S.


    The authors study the changes in adsorption heat of CO/sub 2/ upon the substitution of Na/sup +/ by Ca/sup 2 +/ in faujasite, chabazite, mordenite, erionite, and L zeolites. The substitution of sodium ions by calcuium ions in the crystal lattices of faujasites, chabazites, mordenites, and erionites leads to an increase in the heats of adsorption of carbon dioxide at relatively low occupancies. The extent of the occupancy ranges, for which enhanced heats of adsorption are found, correlate in general with the amounts of calcium cations which may directly interact with the adsorbed molecules.

  5. Characterization of Lewis acid sites on the ,,100... surface of -AlF3: Ab initio calculations of NH3 adsorption

    E-print Network

    . © 2008 American Institute of Physics. DOI: 10.1063/1.2933523 I. INTRODUCTION Strong Lewis acid catalysts is a heterogeneous catalyst and is therefore a promising alternative to SbF5 for use as an indus- trial catalyst.2 is commonly used to quantify the strength of a Lewis acid.14­16 DFT calculations on the zeolite, mordenite,14

  6. 40 The Electrochemical Society Interface Winter 2003 ne quickly realizes that a polymer electrolyte membrane fuel cell

    E-print Network

    Sethuraman, Vijay A.

    catalyst layers, two gas diffusion layers (GDLs), and two sets of sealing gaskets, as shown in Fig. 1. Each with mordenite, a proton conducting, methanol impermeable zeolite. Even in these new membranes, however consists of a proton exchange membrane, three-phase anode and cath- ode catalyst layers, two gas diffusion

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

    SciTech Connect

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


    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.

  8. Fenton Chemistry of FeIII Zeolitic Minerals Treated with

    E-print Network

    Dutta, Prabir K.

    Fenton Chemistry of FeIII -Exchanged Zeolitic Minerals Treated with Antioxidants T O N I A . R U D Fenton activity. Lung lining fluid contains antioxidants, such as glutathione (GSH) and ascorbic acid (AAIII- exchanged erionite and mordenite after treatment with antioxidants. The Fenton assay involved the reaction

  9. American Mineralogist, Volume 85, pages 495508, 2000 0003-004X/00/0304495$05.00 495

    E-print Network

    Benning, Liane G.

    ; Pabalan 1994; Carey Solubility and stability of zeolites in aqueous solution: II. Calcic clinoptilolite-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

  10. Comparative study of n-butane transformation over Pt sulfated zirconia and Pt zeolites

    Microsoft Academic Search

    Hung-chung Wu; Li-jen Leu; Claude Naccache; Kuei-jung Chao


    The hydroconversion of n-butane catalyzed by sulfated zirconium oxide (SZ), H-beta (HBEA) and H-mordenite (HMOR) zeolites of different SiAl ratios with the promotion of platinum has been studied at temperature ranges of 240–340°C and at 1–27.2 atm. The results indicate that, with increased pressure and with an increased SiAl ratio of zeolites the cracking as well as the hydrogenolysis enhance

  11. Supported metal carbonyls: new catalysts for the indirect liquefaction of coal. Final report for period to December 31, 1980

    Microsoft Academic Search



    The synthesis of two series of supported metal catalysts has been achieved. The first series consisted of iron on the oxide supports, MgO, ZnO, TiOâ, AlâOâ, SiOâ and ThOâ; the second comprised iron, cobalt and iron\\/cobalt mixtures on the zeolite supports ZSM-5, NU-1, mordenite and 13X. All potentially active catalytic materials were prepared by techniques developed in our laboratory during

  12. Spectroscopic studies of the zeolite materials: interaction of extra-framework aluminum with acetylacetone and hydroxyl groups

    Microsoft Academic Search

    M. A. Zanjanchi; E. Mohabbati


    Diffuse reflectance spectroscopy has been used to investigate structural modification of different acidic and neutralized zeolites subjected to acetylacetone treatments. Extra-framework aluminum species, produced upon expulsion of aluminum atoms from the framework of the zeolite Y, mordenite, mazzite and ZSM-5 form complexes with acetylacetone. A distinct well-defined 285–290nm band produced is due to the transformation of aluminum atoms to structures

  13. Direct electron crystallographic determination of zeolite zonal structures

    Microsoft Academic Search

    Douglas L. Dorset; Christopher J. Gilmore; Jose Luis Jorda; Stavros Nicolopoulos


    The prospect for improving the success of ab initio zeolite structure investigations with electron diffraction data is evaluated. First of all, the quality of intensities obtained by precession electron diffraction at small hollow cone illumination angles is evaluated for seven representative materials: ITQ-1, ITQ-7, ITQ-29, ZSM-5, ZSM-10, mordenite, and MCM-68. It is clear that, for most examples, an appreciable fraction

  14. Carcinogenic and fibrogenic effects of zeolites: preliminary observations

    SciTech Connect

    Suzuki, Y.


    Two natural zeolite minerals, erionite, a fibrous form, and mordenite, a mixture of fibrous and granular types, were injected intraperitoneally into 45 Swiss albino male mice with a single administration of 10 or 30 mg of zeolite suspended in 1 cc of saline solution. The erionite was 0.4-24 in length (1 average, 95% shorter than 8 and 0.01-2.5 in width (0.1 average, 94.4% smaller than 1 The granular mordenite was 0.33-5.7 in the long axis and 0.27-1.67 in the short axis. The fibrous mordenite was 0.4-6 in length and 0.05-0.67 in width. Thirteen untreated mice and five mice treated with 10 mg chrysotile (Calidria, 90% shorter than 1 were used as controls. Six of ten mice treated with 10 mg of erionite developed malignant peritoneal tumors between 8 and 22 months after the single administration. The neoplasms in four of the six animals were consistent with malignant mesothelioma. Two of four chrysotile-treated controls also developed malignant peritonel mesotheliomas between 9 and 16 months. A fibrogenic effect was noted in both the erionite- and mordenite-treated mice, the effect being more pronounced in the former. Fibrotic lesions induced by these mineral fibers commonly presented in the primary site of these induced peritioneal tumors. Findings suggest that the carcinogenic and fibrogenic effects of the fibrous erionite are similar to those of asbestos.

  15. Determination of relative acid strength and acid amount of solid acids by Ar adsorption

    Microsoft Academic Search

    Hiromi Matsuhashi; Ayumi Futamura


    Relative acid strength and acid amount of solid acids (alumina, silica-alumina, sulfated zirconia, mordenite, ZSM-5, beta, Y, and reduced MoO3) are determined by argon adsorption technique. To obtain the heat of Ar adsorption and saturated adsorption amount, the adsorption isotherm is analyzed using the theory reported by Cremer and Flügge. The obtained heats of Ar adsorption and saturated adsorption amounts

  16. Adsorption of SO 2 from Wet Mixtures on Hydrophobic Zeolites

    Microsoft Academic Search

    Sabina A. Rouf; Mladen Ei?


    Breakthrough curve measurements of SO2 and water vapor were carried out on a number of selected mordenite and pentasil zeolites from their binary and ternary mixtures with CO2 at 50 and 100°C. SO2 capacities of these samples were found to be significantly reduced by the presence of water. Competitive adsorption led to unusually high overshoot peaks of SO2 breakthrough curves.

  17. Hydrogen purification for fuel cells: selective oxidation of carbon monoxide on Pt–Fe\\/zeolite catalysts

    Microsoft Academic Search

    Masahiro Watanabe; Hiroyuki Uchida; Kyoko Ohkubo; Hiroshi Igarashi


    A preferential oxidation of CO remaining in reformed H2 fuels (PROX) is one of the processes to avoid a serious poisoning of anode-catalysts in fuel cells. The crucial requirement for the PROX catalyst is high CO oxidation rate with high selectivity at low-temperatures of ?200°C. We propose new Pt–Fe\\/mordenite catalysts for the PROX, which is extremely superior to conventional Pt\\/Al2O3

  18. Environmental Applications of Natural Zeolitic Materials Based on Their Ion Exchange Properties

    Microsoft Academic Search

    C. Colella; Piazza Ie; V. Tecchio

    \\u000a Present and potential use of natural zeolites as cation exchangers in environmental protection is reviewed. Siliceous zeolites,\\u000a such as chabazite, clinoptilolite, mordenite and phillipsite, exhibit good selectivities for cations with low charge density,\\u000a e.g., Cs+ and NH4\\u000a +, and for cations with low hydration energy, such as Pb2+. Zeolitised tuffs, containing the mentioned zeolites, may therefore be utilised for removing

  19. Transalkylation of toluene and 1,2,4-trimethylbenzene over large pore zeolites

    Microsoft Academic Search

    Yong-Kul Lee; Se-Ho Park; Hyun-Ku Rhee


    Large pore zeolites, H-beta, H-mordenite (H-MOR) and H-omega, were dealuminated by steam treatment followed by acid leaching and were applied for transalkylation of toluene and 1,2,4-trimethylbenzene. The acidic properties of catalysts were examined by using TPD of ammonia and in situ FT-IR spectroscopy in the OH stretching region as well as pyridine adsorbed catalysts. XRD, mid-infrared spectroscopy and 29Si and

  20. Catalytic Dewaxing for Lube Oil Production

    Microsoft Academic Search

    M. F. Menoufy; A. E. Nadia; H. S. Ahmed


    The selective cracking of long-chain normal paraffin's of medium neutral raffinate, derived from a lube oil-phenol extraction unit, by the catalytic dewaxing technique over H-ZSM-5 and NiMo-H-mordenite catalysts was studied. The runs were conducted to produce lube oils with acceptable cold flow properties. The influences of zeolite types, metals loading, and operating reactor temperatures (290°C–475°C) can have a great effect

  1. Magnetic and Moessbauer characterization of iron/zeolite catalysts and syngas conversion studies

    SciTech Connect

    Oskooie-Tabrizi, M.M.


    Bifunctional catalysts containing the medium pore (0.6 nm) zeolite and Group VIII metals, such as Fe or (Fe + Co), are of considerable interest for the conversion of syngas (synthesis gas; H/sub 2/ + CO) to gasoline range (C/sub 5/ - C/sub 11/) hydrocarbons. Various synthetic zeolites used in this study consisted of acidic zeolites, such as H-ZSM-5 and H-mordenite, and a non-acidic zeolite, namely, Silicalite. This investigation was undertaken to: 1) study the effect of the nitrate and carbonyl impregnated methods on the dispersions of Fe; 2) see if the above combinations have any marked effect on the syngas conversion; and explore if there is any metal-support interaction between the Fe clusters and the varying number of acid sites in zeolites, especially with respect to the mordenites. Iron was chosen in this study for a variety of reasons, such as its technological relevance in the commercial Fischer-Tropsch synthesis and its lower cost, as compared with the cost of other transition metals. The Fe/zeolite catalysts were characterized by in-situ magnetization, and Moessbauer techniques. IR spectroscopy was also used in investigating H-mordenites. These catalysts were also tested for their Fischer-Tropsch activity, that is, for the syngas conversion to gasoline range hydrocarbons.

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

    SciTech Connect

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


    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.

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


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


    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

  4. Catalytic degradation of high density polyethylene using zeolites.


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


    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

  5. Non-oxidative removal of hydrogen sulfide from gaseous, petrochemical, and other streams

    SciTech Connect

    Bricker, J.C.; Imai, T.


    This patent describes a method of reducing the hydrogen sulfide level in streams containing hydrogen sulfide at concentrations from about 2 ppm up to about 1,000 ppm. It comprises reacting the hydrogen sulfide with an unsaturated hydrocarbon in the presence of an acidic solid catalyst selected from the group consisting of polymeric sulfonic acid resins, solid polyphosphoric acid, supported sulfuric acid, supported boric acid, silica-aluminas, clays, faujasite, mordenite, and L, omega, X or Y zeolites at mercaptan-forming concentrations, and recovering a stream having a reduced hydrogen sulfide concentration and containing no more than 5 ppm hydrogen sulfide.

  6. Removal of radionuclides using zeolites

    SciTech Connect

    Reddy, R.G.; Cai, Z. [Univ. of Nevada, Reno, NV (United States)


    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.

  7. Syntheses of hydrocarbons from compounds containing one carbon atom using bifunctional zeolite catalysts

    SciTech Connect

    Ione, K.G.; Romannikov, V.N.; Shepelev, S.E.; Stepanov, V.G.


    The laws of the transformations of methanol, the compounds CH/sub 3/X (where X = C1, Br, etc.), CH/sub 4/ + X (X = C1/sub 2/, Br/sub 2/, O/sub 2/, N/SUB x/ O/SUB y/), and CO + H/sub 2/ in the presence of catalytic systems based on type Y zeolites, erionite, mordenite, and silicarich zeolites (VKTs) are considered. A model of the centers catalytically active in hydrocarbon-forming reactions on zeolites is proposed on the basis of results of /sup 27/A1 and /sup 29/Si NMR.

  8. Investigation of structural charge transfer in zeolites by ultraviolet spectroscopy

    SciTech Connect

    Garbowski, E.D.; Mirodatos, C.


    Charge-transfer processes in various zeolites (faujasite, mordenite, ZSM5, erionite, and offretite) are evidenced by means of UV spectroscopy. UV bands at 240 and 320 nm are assigned to two different Al-O units. The band at 240 nm, present whatever the zeolite and whatever the chemical or thermal treatment, is related to framework Al-O units which are ''inert'' toward catalysis and easily removed by dealumination or dehydroxylation. The band at 320 nm, more stable toward dealumination and dehydroxylation, is specifically detected or significantly enhanced for catalytically active samples (methanol conversion, hydrocarbon cracking, and disproportionation). This band could be related to oxoaluminum structures inside the zeolite matrix.

  9. [Effect of chrysotile-asbestos and zeolites dust on generations of reactive oxygen species by alveolar macrophages and granulocytes].


    Gusev, V A; Lomonosova, O S; Velichkovskií, B T


    Different characteristics of the influence of dusts of chrysotile--asbestos, mordenite, erionite and klinoptilolite on the total generation of the active forms of oxygen by the alveolar macrophages and the generation of O2- and H2O2 by the granulocytes give the possibility to connect some of these characteristics with the peculiarity of biological action these dusts. It is discovered the most strong activating properties has the dust of chrysotile--asbestos, and the most cytotoxic effect has the dust of klinoptilolite. PMID:9273777

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

    SciTech Connect

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


    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.

  11. Hexane isomerization and cracking activity and intrinsic acidity of H-zeolites and sulfated zirconia-titania.


    Lónyi, Ferenc; Kovács, Anita; Valyon, József


    Adsorption of N2 was studied on zeolite H-Y, ultrastabilized H-Y (H-USY), H-mordenite, H-ZSM-5, H-beta, and on sulfated zirconia-titania (SZT) mixed oxide by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) at 298 K and at N2 pressures up to 9 bar. The adsorption-induced DeltanuOH red-shift of the nuOH bands was used as a measure of the intrinsic acid strength of the Brnønsted acid sites. The intrinsic acid strength of the solids follows the order of H-ZSM-5 approximately H-mordenite approximately H-beta > H-USY > SZT approximately H-Y. The solids were characterized by their hexane conversion activities at 553 K and 6.1 kPa hexane partial pressure. The reaction was shown to proceed predominantly by a bimolecular mechanism, while the reaction was first order in hexane and zero order in alkenes. The site-specific apparent rate constant of the bimolecular hexane conversion was shown to parallel the intrinsic acid strength of the samples, suggesting that the ratio of the apparent and the intrinsic activity, that is, the KA' equilibrium constant of alkane adsorption on the hydrocarbon-covered sorption sites, is hardly dependent on the catalyst structure. PMID:16471737

  12. 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.


    The concentration of one-electron transfer sites on the surface of H-ZSM-5, H-Y, H-mordenite, and H-? 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-? > 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.

  13. Fourier self-deconvolution of the IR spectra as a tool for investigation of distinct functional groups in porous materials: Brønsted acid sites in zeolites.


    Vazhnova, Tanya; Lukyanov, Dmitry B


    For many decades, IR and FT-IR spectroscopy has generated valuable information about different functional groups in zeolites, metal-organic frameworks (MOFs), and other porous materials. However, this technique cannot distinguish between functional groups in different local environments. Our study demonstrates that this limitation could be overcome by using Fourier self-deconvolution of infrared spectra (FSD-IR). We apply this method to study three acidic mordenite zeolites and show (i) that these zeolites contain six distinct Brønsted acid sites (BAS) as opposed to 2-4 different BAS previously considered in literature and (ii) that the relative amounts of these BAS are different in the three zeolites examined. We then analyze possible locations of six BAS in the mordenite structure and explain a number of conflicting results in literature. On this basis, we conclude that the FSD-IR method allows direct visualization and examination of distributions of distinct BAS in zeolites, thus providing a unique research opportunity, which no other method can provide. Given the similarities in the IR analysis of different functional groups in solids, we expect that the FSD-IR method will be also instrumental in the research into other porous materials, such as solid oxides and MOFs. The latter point is illustrated by FSD of the IR spectrum of hydroxyl groups in a sample of ?-alumina. PMID:24219854

  14. Comparative investigation of the catalytic properties of crystalline aluminosilicates of different types. 2. Selectivity in the cracking of n-octane

    SciTech Connect

    Stepanov, V.G.; Mastikhin, V.M.; Ione, K.G.


    This investigation examines the dependence of the rate and selectivity of the cracking of n-octane over zeolites of the above-mentioned types on the state of the aluminum atoms present. To ensure the correctness of the comparative determinations of the catalytic properties of the zeolites, the contact times were varied over a range of three to four orders of magnitude. Results indicated that the cracking of paraffins over decationized type Y zeolites, mordenites, erionite, and high-silica zeolites (HSZ) occurs by the same route: paraffins ..-->.. unsaturated fragments ..-->.. paraffinic fragments and monoaromatic hydrocarbons ..-->.. polyalkylaromatic (nondesorbed) compounds. The extent of conversion of the intermediate products, and hence the selectivity of cracking, was determined for erionite by the geometrical parameters of the pore structure, and for type Y zeolites, mordenites, and HSZ, by the concentration of groups which include aluminum atoms in cationic positions. Results also indicated that on type Y zeolites with the greatest concentration of aluminum atoms in cationic positions, conversion of the hydrocarbons proceeds as far as the formation of nondesorbed compounds, and on HSZ with the lowest concentration of such sites, it proceeds as far as the formation of monaromatic compounds.

  15. Significance of mass and number of fibers in the correlation of V79 cytoxicity with tumorigenic potential of mineral fibers

    SciTech Connect

    Palekar, L.D.; Most, B.M.; Coffin, D.L.


    The cytotoxicity of four tumorigenic minerals: erionite(w), erionite(c), UICC crocidolite, UICC chrysotile and nontumorigenic mordenite was compared in Chinese hamster lung V79 cells. The results indicate that the tumorigenic minerals were toxic by showing more than 50% toxicity for at least one dose between 10 and 100/sup +/g/ml. Mordenite was nontoxic. Higher potency of erionite, however, was not evident in this system when the dose considered was expressed in mass units. On the other hand, when the degree of cytotoxicity was considered per number of mineral fibers, it was clear that fewer erionite fibers of all three dimensions (A greater than or equal to 3; L greater than or equal to 8.0, W less than or equal to 0.25; and L less than or equal to 5.0, W less than or equal to 0.1 than those of UICC crocidolite and UICC chrysotile were needed to produce similar toxicity. This suggests that the dose in number of fibers may be a better parameter than the total mass dose as a correlate of tumorigenic potential.

  16. A comparative investigation of the catalytic properties of crystalline aluminosilicates of different types. 2. Selectivity in the cracking of n-octane

    SciTech Connect

    Stepanov, V.G.; Mastikhin, V.M.; Ione, K.G.


    This investigation examines the dependence of the rate and selectivity of the cracking of n-octane over zeolites on the state of the aluminum atoms present. To ensure the correctness of the comparative determinations of the catalytic properties of the zeolites, the contact times were varied over a range of three to four orders of magnitude. The cracking of paraffins over decationized type Y zeolites, mordenites, erionite, and high-silica zeolites (HSZ) occurs by the same route: paraffins ..-->.. unsaturated fragments ..-->.. paraffinic fragments and monoaromatic hydrocarbons ..-->.. polyalkylaromatic (nondesorbed) compounds. The extent of conversion of the intermediate products, and hence the selectivity of cracking, is determined for erionite by the geometrical parameters of the pore structure, and for type Y zeolites, mordenites, and HSZ, by the concentration of groups which include aluminum atoms in cationic positions. On type Y zeolites with greatest concentration of aluminum atoms in cationic positions, conversion of the hydrocarbons proceeds as far as the formation of nondesorbed compounds, and on HSZ with the lowest concentration of such sites, it proceeds as far as the formation of monoaromatic compounds.

  17. Removal of metal cations from water using zeolites

    SciTech Connect

    Zamzow, M.J.; Murphy, J.E. (U.S. Bureau of Mines, Reno, NV (United States))


    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.

  18. Hydrodewaxing with mixed zeolite catalysts

    SciTech Connect

    Chester, A.W.; McHale, W.D.; Yen, J.H.


    A process is described for catalytically dewaxing a hydrocarbon lubricating oil feedstock comprising contacting the feedstock with a dewaxing catalyst, the dewaxing catalyst comprising, in combination: (a) a zeolite catalyst having a Constraint Index not less than 1, (b) an acidic catalytic material selected from the group consisting of Mordenite, TEA Mordenite, Dealuminized Y, Ultrastable Y, Rare Earth Y, amorphous silica-alumina chlorinated alumina, ZSM-4 and ZSM-20, and (c) a hydrogenation component, and recovering a dewaxed product. A process is also described for catalytically dewaxing a hydrocarbon lubricating oil feedstock comprising contacting the feedstock with a dewaxing catalyst, the dewaxing catalyst comprising, in combinations: (a) a first zeolite catalyst selected from the group consisting of ZSM-5, ZMS-11, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, TMA Offretite and Erionite, (b) a second catalyst selected from the group consisting of ZSM-12, ZSM-22, ZSM-38 and ZSM-48, the second zeolite catalyst being different from the first zeolite catalyst, and (c) a hydrogenation component, and recovering a dewaxed product.

  19. Calibration analysis of zeolites by laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Hor?á?ková, M.; Grolmusová, Z.; Hor?á?ek, M.; Rakovský, J.; Hudec, P.; Veis, P.


    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.

  20. [In vitro research on the interaction of natural zeolites with diploid cells from the human embryonic lung].


    Nikolova, S; Vinarova, M; Kirov, G; Bradvarova, I


    A study of the biological effect of the natural zeolites, clinoptilolite, mordenite and erionite on monostratum cellular culture of human embryonic lung is performed. The number of pyknotic cells, morphological changes in the cells, and monostratum, mitotic activity and changes in the cellular culture are reported during a continuous experiment. As positive control is used standard quartz dust DQ-12 and for negative dust of TiO2. It is already established that the dust particles of natural zeolites with dimensions under 5 micron display biological aggressiveness. With most strongly expressed effect is the clinoptilolite dust, which related to identical active surface, is comparable to that of quartz DQ-12. The mordenite is with moderate cytotoxic effect, proportional to the time and concentration, while erionite is with slight and very delayed effect. There are differences concerning the effect on the miotic activity of the cells. The biologic aggressiveness of the zeolites is discussed in relation to their strong active surface, their ionometabolic properties and their capacity to generate hydrogen at moistering. PMID:2831534

  1. Radioactive iodine separations and waste forms development.

    SciTech Connect

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


    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 using competing groundwater anions (HCO3-, Cl- and SO42-). Distinct variations in solubility were found that related to the structures of the materials.

  2. Reactions of bicyclo(2,2. 1)hepta-2,5-diene in the presence of zeolites

    SciTech Connect

    Azbel', B.I.; Gol'dshleger, N.F.; Isakov, Ya.I.; Epel'baum, E.T.; Yampol'skii, Yu.Yu.; Minachev, Kh.M.


    In the interaction of bicyclo(2.2.1)hepta-2,5-diene with decationized and rare-earth zeolites (H-TsVM, H-Ultrasil, H-mordenite, NaNdY), including the dealuminized NdNaY', wide-pore aluminosilicates and filled zeolite (AShNTs), activated under conditions such that sorbed water remains in (or is added to) the catalyst, alcohols are formed - 3-hydroxynortricyclane and 3-dehydronorborneol - together with ethers 3-(tricyclo( 2,6/)-3'-heptyloxy)-bicyclo(2.2.1)hept-5-ene and 3,3'-oxydinortricyclane. With aromatic compounds in the presence of wide-pore REE-Y zeolites and also AShNTs, activated at 500/sup 0/C, norbornadiene forms alkylated products such as endo-5-phenyl-2-norbornene from benzene.

  3. 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


    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.

  4. Use of SZM-57 in catalytic cracking for gasoline octane improvement and co-production of light olefins

    SciTech Connect

    Chitnis, G.K.; Herbst, J.A.; Valyocsik, E.W.


    This patent describes a catalytic cracking process. it comprises: catalytically cracking a hydrocarbon feed with a cracking catalyst composition comprising, as a first component, a large pore crystalline molecular sieve and, as a second component, ZSM-57, wherein the second component comprises from about 0.01 to about 25 wt. % of the total cracking catalyst composition, and wherein the first component is selected from the group consisting of zeolite X, Y, USY, dealuminated X, dealuminated USY, Dealuminated-silicon-enriched zeolite X, dealuminated-silicon-enriched zeolite Y, dealuminated-silicon-enriched USY, Zeolite Omega, ZSM-20 mordenite, Zeolite Beta, Zeolite L, MCM-9, SAPO-5, SAPO-37, SAPO-31, SAPO-40, SAPO-41, AlPO{sub 4{minus}5}, AlPO{sub 4{minus}8}, VPI-5, and mixtures thereof.

  5. Xenon NMR studies of dynamics and exchange in zeolites

    SciTech Connect

    Moudrakovski, I.L.; Ratcliffe, C.I.; Ripmeester, J.A. [Steacie Institute for Molecular Sciences, Ottawa, Ontario (Canada)


    We have found, despite earlier reports to the contrary, that for many microporous solids with one-dimensional channels (ZSM-12, ALPO-5, VPI-5, SSZ-24) the chemical shift has an anisotropic component. For ALPO-11, a detailed model has been developed which accounts for the loading-dependent chemical shift in terms of intraparticle exchange of statistical distributions of xenon atoms with 0, 1 or 2 nearest neighbors. A similar model can be applied to ZSM-12 up to moderate loadings. At higher loading levels 2D exchange methods show that interparticle exchange occurs as well. The same approach was used to study interparticle exchange in X and Y zeolite mixtures, exchange amongst zeolite clusters of up to 8 xenon atoms in the supercages of AgA zeolite, and main channel - side pocket exchange in mordenite. The parameters derived are directly relevant to the understanding of sorption and diffusion processes in zeolites.

  6. Cone-angle Dependence of Ab-initio Structure Solutions Using Precession Electron Diffraction

    NASA Astrophysics Data System (ADS)

    Ciston, James; Own, Christopher S.; Marks, Laurence D.


    Precession electron diffraction (PED) is a technique which is gaining increasing interest due to its ease of use and reduction of the dynamical scattering problem in electron diffraction, leading to more direct structure solutions. We have performed a systematic study of the effect of precession angle for the mineral andalusite on kinematical extinctions and direct methods solutions where the semiangle was varied from 6.5 to 32 mrad in five discrete steps. We show that the intensities of kinematically forbidden reflections decay exponentially as the precession semiangle (?) is increased and that the amount of information provided by direct methods increases monotonically but non-systematically as ? increases. We have also investigated the zeolite-framework mineral mordenite with PED and have found a direct methods solution where the 12-ring is clearly resolved for the first time.

  7. Deuterium solid-state NMR study of the dynamics of molecules sorbed by zeolites

    SciTech Connect

    Eckman, R.R.; Vega, A.J.


    The dynamics of small organic molecules sorbed by zeolite molecular sieves has been investigated by using solid-state deuterium NMR. The systems studied include methanol, benzene, toluene, and p-xylene sorbed by zeolites ZSM-5, mordenite, Y, and erionite. The dynamics of uptake or filling of the zeolite void volume has been observed. Intracrystalline molecular motion has been observed and used to characterize the molecular sieve effect. For example, a preferred diffusion of p-xylene in the straight channels of ZSM-5 has been observed, which tends to support the theory of molecular traffic control. The physical state of physisorbed species is described in the light of the deuterium NMR results. The behavior of sorbed molecules is characterized as that of surface-adsorbed species. The effects of site-selective adsorption and diffusion on the state of sorbed species is described.

  8. Comparative investigation of the catalytic properties of crystalline aluminosilicates of various types. Communication 3. Selectivity of the conversion of methanol on zeolites of various types

    SciTech Connect

    Stepanov, V.G.; Gonyshev, A.P.; Ione, K.G.


    Zeolites of types A, X, and Y are used as catalysts for the dehydration of alochols to olefins. In view of the interest in the synthesis of fuel from nonpetroleum raw material, the process of high-temperature conversion of alcohol is considered as a promising method for obtaining gasolines. In particular, a method has been developed for obtaining high-octane fuels from methanol using silica-rich zeolites of the ZSM type. In the present investigation a comparative study has been made of the selectivity of the action of zeolites of the type of mordenite and erionite and of silica-rich zeolites (TsVK) in reactions of methanol at various contact times.

  9. Biological effects of minerals

    SciTech Connect

    Guthrie, G.D. Jr.


    In general, clay materials exhibit a range of biological activities, from apparently inactive or slightly active, such as hematite, to highly fibrogenic and carcinogenic, such as fibrous brucite (nemalite). The zeolites also exhibit such as range, with some mordenite being slightly active and erionite being highly active; however, erionite is the only zeolite that has been studied extensively. The diversity of mineral species holds great potential for probing these mechanisms, especially when mineralogical data are integrated with biological data. Unfortunately, many of the studies reporting data on the biological effects of clays and zeolites fail to report detailed mineralogical information; hence, it is difficult at present to interpret the biological activities of minerals in terms of their physical and chemical properties. Important mineralogical data that are only rarely considered in biological research include exact mineralogy of the specimen (i.e., identification and abundance of contaminants), physical and chemical properties of minerals, and surface properties of minerals. 141 refs., 1 fig., 8 tabs.

  10. Supercritical fluid removal of hydrocarbons adsorbed on wide pore zeolite catalysts

    SciTech Connect

    Lucia M. Petkovic; Daniel M. Ginosar; Kyle C. Burch


    The effect of zeolite pore structure on coke removal by supercritical fluid regeneration (SFR) was studied on a series of wide pore zeolite catalysts, which included acidic Y, beta, L, and mordenite zeolites. Catalyst samples were deactivated under liquid phase isobutane/butene alkylation reaction conditions and treated under flowing supercritical isobutane for 60 min. The chemical nature of the species remaining on the catalyst surface before and after SFR was analyzed by temperature-programmed oxidation (TPO), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and ultraviolet-visible (UV-Vis) spectroscopy. Zeolite pore structure played an important role not only in hydrocarbon deposition during alkylation but also in hydrocarbon transformation and removal during SFR. During SFR, the formation of unsaturated cyclic or polycyclic compounds, which likely affects catalyst long-term activity after cyclic alkylation/SFR treatments, was hindered on beta zeolites and favored on catalysts containing periodic expansions or cages, such as Y and L zeolites.

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

    SciTech Connect

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


    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.

  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.


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

    SciTech Connect



    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.

  14. Studies of anions sorption on natural zeolites.


    Barczyk, K; Mozgawa, W; Król, M


    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

  15. Direct electron crystallographic determination of zeolite zonal structures.


    Dorset, Douglas L; Gilmore, Christopher J; Jorda, Jose Luis; Nicolopoulos, Stavros


    The prospect for improving the success of ab initio zeolite structure investigations with electron diffraction data is evaluated. First of all, the quality of intensities obtained by precession electron diffraction at small hollow cone illumination angles is evaluated for seven representative materials: ITQ-1, ITQ-7, ITQ-29, ZSM-5, ZSM-10, mordenite, and MCM-68. It is clear that, for most examples, an appreciable fraction of a secondary scattering perturbation is removed by precession at small angles. In one case, ZSM-10, it can also be argued that precession diffraction produces a dramatically improved 'kinematical' data set. There seems to no real support for application of a Lorentz correction to these data and there is no reason to expect for any of these samples that a two-beam dynamical scattering relationship between structure factor amplitude and observed intensity should be valid. Removal of secondary scattering by the precession mode appears to facilitate ab initio structure analysis. Most zeolite structures investigated could be solved by maximum entropy and likelihood phasing via error-correcting codes when precession data were used. Examples include the projected structure of mordenite that could not be determined from selected area data alone. One anomaly is the case of ZSM-5, where the best structure determination in projection is made from selected area diffraction data. In a control study, the zonal structure of SSZ-48 could be determined from selected area diffraction data by either maximum entropy and likelihood or traditional direct methods. While the maximum entropy and likelihood approach enjoys some advantages over traditional direct methods (non-dependence on predicted phase invariant sums), some effort must be made to improve the figures of merit used to identify potential structure solutions. PMID:17240069

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


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


    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 depended on the type of zeolite, suggesting that the surface structure of the zeolite plays an important role. PMID:12417479

  17. Fracture-coating minerals in the Topopah Spring Member and upper tuff of Calico Hills from drill hole J-13

    SciTech Connect

    Carlos, B.


    Fracture-lining minerals from drill core in the Topopah Spring Member of the Paintbrush Tuff and the tuff of Calico Hills from water well J-13 were studied to identify the differences between these minerals and those seen in drill core USW G-4. In USW G-4 the static water level (SWL) occurs below the tuff of Calico Hills, but in J-13 the water table is fairly high in the Topopah Spring Member. There are some significant differences in fracture minerals between these two holes. In USW G-4 mordenite is a common fracture-lining mineral in the Topopah Spring Member, increasing in abundance with depth. Euhedral heulandite >0.1 mm in length occurs in fractures for about 20 m above the lower vitrophyre. In J-13, where the same stratigraphic intervals are below the water table, mordenite is uncommon and euhedral heulandite is not seen. The most abundant fracture coating in the Topopah Spring Member in J-13 is drusy quartz, which is totally absent in this interval in USW G-4. Though similar in appearance, the coatings in the vitrophyre have different mineralogy in the two holes. In USW G-4 the coatings are extremely fine grained heulandite and smectite. In J-13 the coatings are fine-grained heulandite, chabazite, and alkali feldspar. Chabazite has not been identified from any other hole in the Yucca Mountain area. Fractures in the tuff of Calico Hills have similar coatings in core from both holes. In J-13, as in USW G-4, the tuff matrix of the Topopah Spring Member is welded and devitrified and that of the tuff of Calico Hills is zeolitic. 11 refs., 10 figs., 5 tabs.

  18. Compositional and kinetic studies on the crystallization of zeolite beta using cost-efficient TEABr without seed under static and stirred conditions

    NASA Astrophysics Data System (ADS)

    Lee, Young Jong; Kim, Shin Dong; Byun, Soon Churl; Park, Jun Woo; Jeong, Yeon Jun; Kwon, Yoon Jung; Song, Hee Oeul; Kim, Wha Jung


    Zeolite beta was successively synthesized in the presence of TEABr as organic template within 36 h under static and stirred conditions at 423 K. In order to clearly demonstrate the effects of individual component and interaction between components on the crystallization of zeolite beta using TEABr, a ternary compositional diagram for TEABr, Al 2O 3 and Na 2O was drawn at constant SiO 2 and H 2O contents. There are mainly three compositional zones in which zeolites, beta, ZSM-5 and mordenite are formed. The results suggest that Na + cation should have acted as structure-directing agent as well as charge balancing for AlO 2-, leading the crystallization toward the formation of mordenite or ZSM-5 depending on its content. The results clearly show that the crystallization toward pure zeolite beta becomes favorable at lower Al 2O 3 content. In addition, it is interesting to notice that Na 2O and Al 2O 3 contents would play key roles simultaneously in the crystallization toward the formation of pure zeolite beta. The results of thermal analysis show that TEA + ion also partially acts as charge-balancing agent depending on Al content, that is, it is more likely to interact with Si-O - rather than with Al-O - at lower Al content, thus resulting in the more decomposition of TEA + ions interacting with Si-O - at lower Al content in temperature range between 473 and 623 K. The kinetic study based on 3Na 2O-18TEABr-0.8Al 2O 3-25SiO 2-440H 2O was conducted at 413, 418 and 423 K, respectively, and the results suggest that as long as a correct crystallization temperature is applied to the synthesis of zeolite beta, the crystallization of zeolite beta does not seem to be so sensitive to temperature.

  19. 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. [ORNL; Jubin, R. T. [ORNL


    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 capacity by Ag0Z in the presence of NOx is unaffected by the addition of water vapor to the gas stream; no marked additional loss in capacity or retention was observed.

  20. Ice-like H2O in hemimorphite, Zn4Si2O7(OH)2H2O: Cp and entropy behavior of confined H2O in microporous silicates

    NASA Astrophysics Data System (ADS)

    Geiger, C. A.; Dachs, E.


    The H2O molecule plays a key role in many planetary processes and, thus, it is necessary to investigate how it interacts with a variety of natural materials. In this regard the role of hydrogen bonding is of central importance, but it has received relatively little study. Certain micro/nanoporous silicates offer the possibility for one to investigate the nature of confined H2O and hydrogen bonding at a relatively simple, yet fundamental level. Hemimorphite, Zn4Si2O7(OH)2.H2O, and its dehydrated analog Zn4Si2O7(OH)2 were studied by low-temperature relaxation microcalorimetry and their heat capacity determined to analyze the behavior of the confined H2O between 5 and 300 K. An analysis of the data, which are corrected for the presence of a phase transition, shows that the Cp of H2O in hemimorphite behaves more similar to the Cp of ice than to liquid water or steam. The H2O molecule, with its four planar hydrogen bonds in hemimorphite, as well as its tetrahedral coordination in ice, is more rigidly hydrogen bonded in both than in liquid water. This is reflected in their respective Cp behavior. The heat capacity and entropy for the dehydration reaction at 298 K are ?Cprxn = -2.1 ± 3.6 J/molK and ?Srxn = 134.7 ± 4.0 J/molK. Cp behavior at 0 K < T < 300 K and entropy values at 298 K for confined H2O in various microporous silicates were analyzed. The entropy for confined H2O in hemimorphite, and the two zeolites analcime, and mordenite is approximately 54 J/molK at 298 K, while that for cordierite is considerably larger. The strength of the interactions (e.g., H bonding) between a H2O molecule and its surroundings increases approximately from steam > cordierite > analcime > hemimorphite ? mordenite > heulandite > natrolite ? scolecite > liquid H2O > ice and, in the case of microporous silicates, is inversely proportional to the S of the confined H2O.

  1. A computational investigation of ring-shift isomerization of sym-octahydrophenanthrene to sym-octahydroanthracene catalyzed by acidic zeolites.


    Nie, Xiaowa; Janik, Michael J; Guo, Xinwen; Song, Chunshan


    The ring-shift isomerization of sym-octahydrophenanthrene (sym-OHP) to sym-octahydroanthracene (sym-OHA) catalyzed by acidic zeolites (Mordenite (MOR) and Faujasite (FAU)) was investigated by the ONIOM(DFT:UFF) and DFT approaches. A "five-membered ring" mechanism through carbocation rearrangement via 1-2 migration was proved to be kinetically favored over a "six-membered ring" mechanism through Friedel-Crafts reactions. Computational studies based on the "five-membered ring" mechanism demonstrate that a decreasing Brønsted acid site strength from Al-H-MOR to Ga-H-MOR to B-H-MOR reduces the catalytic activity. The catalyst acid site strength would thereby impact the yield of sym-OHA. The isomerization barrier increases when using an Al-H-FAU catalyst that has a similar Brønsted acid site strength as Al-H-MOR but considerably bigger cages, indicating that apart from the desired density and strength of acid sites, optimal zeolite catalysts should have a pore size that better fits the intermediates and transition states. DFT calculations on Gibbs free energy were performed to evaluate the equilibrium ratios of sym-OHA to sym-OHP at specific reaction temperatures from 175 to 325 °C. The results indicate that reaction temperature has a moderate impact on the equilibrium yield of sym-OHA, whose formation is relatively favorable at a lower temperature under experimental conditions. PMID:23015038

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

    SciTech Connect

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


    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.

  3. 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.


    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.

  4. NO decomposition in non-reducing atmospheres. Technical progress report, June 1995--August 1995

    SciTech Connect

    Klier, K.; Herman, R.G.; Dedecek, J.


    Samples of Mn(II) Nafion, MN(II)-A zeolite, and various Co(II)-ZSM-5 zeolites were prepared by aqueous ion exchange techniques. Co(II)- and Mn(II)-containing ZSM-5, erionite, and mordenite were obtained from other sources. Co(II)-containing samples were studied by diffuse reflectance spectroscopy in the dehydrated state and after exposure to NO atmosphere. In addition, the magnetic susceptibilities of these samples were determined. It was shown that two NO molecules were adsorbed onto each Co(II) ion in ZSM-5 and erionite. The visible spectrum of these materials was complex and contained absorption bands corresponding to Co(II) ions in different coordination states. NO desorbed from Co(II) high silica zeolites at temperatures under 190{degrees}C, while it completely desorbed from Co(II) Nafion below 160{degrees}C. The catalytic activity of Co, Cu, and Mn Nafion samples for NO decomposition was probed, but no activity was observed. Optical absorption and luminescence studies are being initiated with Mn(II)-containing samples.

  5. Zeolites for fixation of cesium and strontium from radwastes by thermal and hydrothermal treatments

    SciTech Connect

    Komarneni, S.; Roy, R.


    Several zeolites were heated in air up to 100/degree/C for 4 h or heated hydrothermally at 300/degree/C for 4 weeks under a confining pressure of 300 bar after loading with Cs or Sr to determine the extent and nature of Cs and Sr fixation. Cs-loaded zeolites leached with 0.1 N KCl solution indicated that clinoptilolite, chabazite, erionite, and mordenite fixed only 7% to 26% of their Cs after heat treatment up to 800/degree/C. However, analcite and phillipsite fixed 84% and 81% of their Cs by heat treatments to only 200 and 500/degree/C, respectively. The fixation in analcite may be attributed to its dehydration, while in phillipsite the fixation is attributed to its transformation to cesium aluminosilicate minerals. Analcite and phillipsite were also very effective in Sr fixation just as they were in Cs fixation. Analcite and phillipsite fixed 86% and 91% of their Sr by heat treatment to 420 and 600/degree/C, respectively. Phillipsite may be ideally suited for radioactive waste decontamination followed by thermal or hydrothermal treatment to fix the sorbed Cs and Sr. 17 refs.

  6. Activity of zeolite-containing catalysts in the pyrolysis of low-quality gasolines

    SciTech Connect

    Tagiev, D.B.; Sharifova, E.B.; Zeinalova, F.A.; Zul'fugarov, Z.G.; Minachev, Kh.M.


    The effect of the composition and structure of the zeolite component on the activity of zeolite-containing catalysts in the production of small olefins by the pyrolysis of low-quality gasoline. The experiments were carried out in a laboratory flow system with a fixed catalyst bed. The catalysts had a magnesium silicate carrier containing different cationic forms of y-type synthetic zeolites, chabazite, erionite, and mordenite, as well as a natural clinoptilolite zeolite obtained from the Aidag deposit in the Azerbaidzhan SSR. The hydrocarbon raw material was a low-quality Karachukhur gasoline with an octane rating of 42. The experiments were carried out in the range 550/sup 0/ to 650/sup 0/C and volumetric flow rate of the liquid raw material of from 1 to 5 h/sup -1/. The gaseous reaction products were analyzed chromatographically. The major factors affecting olefin formation in the presence of zeolite-containing catalysts are the temperature of the pyrolysis of the liquid hydrocarbons and volumetric flow rate of the raw material. 2 figures, 1 table. (DP)

  7. Cracking of n-decane on zeolite catalysts: Enhancement of light hydrocarbon formation by the zeolite field gradient

    SciTech Connect

    Mirodatos, C. (Institut de Recherches sur la Catalyse, Villeurbanne (France)); Barthomeuf, D. (Universite Paris (France))


    The selectivity in the cracking of n-decane and, more generally, n-alkanes in zeolites ZSM-5, erionite, offretite, mordenite, and faujasite is characterized by the ratios C{sub 2}/C{sub 4} and C{sub 3}/C{sub 4}, independent of the olefinic or branched character of the products. It is proposed that when high ratios are observed, the nonclassical cracking mechanism through pentacoordinated carbonium ion (PCI) prevails over the classical {beta}-scission mechanism. Low values would characterize the reverse trend. The PCI pathway is associated with the presence of high field gradients arising from at least on of three parameters: highly constraining porosity (small pores and/or tortuosity); low charge density (low Al content, i.e., low density of positive charges, namely protons and metal cations); and polarizing cations. The field gradient selectivity does not depend on the acid strength itself, nor straightforwardly on the pore volume left free after coke deposition. It is proposed that the ratios C{sub 2}/C{sub 4} and C{sub 3}/C{sub 4} be considered field gradient selectivity indexes.

  8. Assignment of Nonclassical [Cu(CO)(n)](+) (n = 1, 2) Complex Ions in Zeolite Cages.


    Iwamoto, Masakazu; Hoshino, Yasuyuki


    A time-resolved FT-IR technique combined with an isotopic tracer method has been applied to study CO adsorbates on Cu(+) ions in copper ion-exchanged zeolites. Three kinds of monocarbonyl species were found to adsorb strongly on Cu-zeolite samples after admission and subsequent evacuation of gas phase CO at room temperature. Their absorption bands were observed at 2146-2160, 2128-2150, and 2097-2129 cm(-1), respectively, dependent on the zeolite structures. In the presence of gaseous CO, the monocarbonyl species at 2146-2160 cm(-1) (so called nonclassical [Cu(CO)](+) complexes) could react with a CO molecule to form a dicarbonyl species [Cu(CO)(2)](+) with nu(sym) bands at 2169-2180 cm(-1). The reactivity of the nonclassical [Cu(CO)](+) complexes was dependent on the zeolite structures, ferrierite > mordenite > ZSM-5 > X-type left harpoon ovet right harpoon offretite/erionite left harpoon ovet right harpoon Y-type > L-type. The remaining two types of monocarbonyl species have little been affected by gas phase CO. PMID:11666867

  9. Alteration history studies in the Exploratory Studies Facility, Yucca Mountain, Nevada, USA

    SciTech Connect

    Levy, S.S; Chipera, S.J. [Los Alamos National Lab., NM (United States); Norman, D.I. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Geoscience


    By mid-1995, the Exploratory Studies Facility (ESF) extended about 1. 1 km from Exile Hill westward toward Yucca Mountain, mostly within densely welded, devitrfied Tiva Canyon Tuff. Secondary mineral occurrences in this unit include breccia cements of mordenite, a fibrous zeolite, and vapor-phase deposits of silica, alkali feldspar, apatite, hollandite, amphibole, and zircon. Calcite is also a common secondary mineral in faults and fractures. Studies of water and gas contents in fluid inclusions in calcites from a fault in nonwelded tuff and a fracture in densely welded tuff suggest mineral deposition under transient locally saturated conditions. Calcite in the nonwelded tuff incorporated air from the unsaturated tuff adjacent to the fault. A highly altered interval within pre-Pah Canyon tuffs just above the top of the Topopah Spring Tuff may be a fossil fumarole or other hydrothermal feature associated with cooling pyroclastic deposits, overprinted by later zeolitic alteration. The observed quartz, cristobalite, opal-CT, and fluorite have been widely identified as products of syngenetic devitrification and vapor-phase alteration in and above the Topopah Spring Tuff. Smectite, also an abundant secondary mineral at the ESF site, has been observed elsewhere at this stratigraphic level. Zeolitic alteration of nonwelded tuffs above the Topopah Spring Tuff, as seen in the ESF, has also been noted in drill core and outcrop at northeastern Yucca Mountain. The hydrologic and geochemical conditions that favored zeolitization only in certain areas of this stratigraphic interval have yet to be determined.

  10. Catalytic decomposition of nitrous oxide on metal exchange zeolites

    SciTech Connect

    Armor, J.N.; Cook, P.J.; Farris, T.S.; Battavio, P.J.; Braymer, T.A.; Li, Yuejin [Air Products and Chemicals Inc., Allentown, PA (United States)


    Nitrous oxide (N{sub 2}O) is now considered to be an environmental pollutant because it contributes to catalytic ozone destruction in the stratosphere and is a greenhouse gas. With increasing concerns about the environment, there is a need to develop catalytic methods to avoid emission of N{sub 2}O into the atmosphere. Earlier catalysts work produced a variety of metal oxide catalysts that were often too slow or operated at too high a temperature to be of commercial significance. The authors have discovered a family of metal loaded zeolite catalysts that have high activity and selectivity for the decomposition of N{sub 2}O into only N{sub 2} and O{sub 2}. Cu and Co exchanged ZSM-5, mordenite, zeolite beta, ZSM-11 and ferrierite are much more active than other cation-exchanged zeolites (Cu-Y, Co-Y, Co-erionite, Cu-L, Co-L, Ni-ZSM-5, Mn-ZSM-5) and metal oxides (CuO/Al{sub 2}O{sub 3}, and CoO/Al{sub 2}O{sub 3}). These improved catalysts readily destroy N{sub 2}O at both low (ppm) and high (30%) levels in the presence of 2% water vapor. The catalysts possess remarkable life and stability over a broad temperature range. The authors shall focus on the performance of these catalysts under a variety of process streams.

  11. Thermodynamic modeling of natural zeolite stability

    SciTech Connect

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


    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.

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


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


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


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


    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

  14. 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.


    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.

  15. 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.


    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.

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


    Sato, Itaru; Kudo, Hiroaki; Tsuda, Shuji


    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

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


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


    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

  18. Binding and catalytic reduction of NO by transition metal aluminosilicates

    SciTech Connect

    Klier, K.; Herman, R.G.; Hou, Shaolie.


    The objective of this research is to provide the scientific understanding of processes that actively and selectively reduce NO in dilute exhaust streams, as well as in concentrated streams, to N{sub 2}. Experimental studies of NO chemistry in transition metal-containing aluminosilicate catalysts are being carried out with the aim of determining the chemical rules for NO reduction on non-precious metals. The catalyst supports chosen for this investigation are A and Y zeolites, mordenite, and monoliths based on cordierite. The supported transition metal cations that were examined are principally the first row redox metals, e.g. Cr(2), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Cu(I). The reactions of interest are the reductions of NO by H{sub 2}, CO, and CH{sub 4}, as well as the disproportionation of NO. Rare earth cations that possess redox properties were placed in the more shielded sites, e.g. Site I in Y zeolite, prior to or simultaneously with the exchange procedure with the transition metal cations. Theoretical calculations of the electronic structure of the transition metal cations in zeolitic sites were carried out by ab initio methods. The aim of this part of the research is to find the best match between the metal-based antibonding orbitals and the antibonding orbitals of the NO molecule such that the N-O bond is weakened and is readily broken. 9 refs., 4 figs., 3 tabs.

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

    USGS Publications Warehouse

    Fournier, R.B.


    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)

  20. Improvement of jet fuel properties by paraffin isomerization

    SciTech Connect

    Oblad, A.G.; Shabtai, J. (Univ. of Utah, Salt Lake City (USA)); Coppola, E.N. (AFRPL/MKPA, Edwards Air Force Base, CA (USA))


    The quality of jet fuels could be significantly improved if long-chain n-paraffins present as components in such fuels are subjected to skeletal hydroisomerization into branched paraffins. The reduced surface tension and viscosity of hydroisomerized products can be expected to improve atomization and combustion, while reduced freezing point could allow the use of broader boiling fuel distillates. This paper summarizes results obtained in a hydroisomerization study using 2 types of paraffinic feedstocks: (a) pure n-alkanes, in particular n-hexadecane; and (b) a hydrotreated diesel fuel, b.p. 83-292{degree}C, containing 25.6 wt% of n-alkanes. A series of Pd- and Pt-loaded mordenite and Y-type zeolite catalysts, containing between 0.5-4.0 wt% of the metals, were used in the study. These catalysts were first screened for hydroisomerization activity in the temperature range of 200-300{degree}C (1 atm H{sub 2} pressure) using a gas-phase flow reactor and n-octane as reactant. It was found that the hydroisomerization selectivity of PtCaY-type zeolite catalysts, as expressed by the ratio of isomerized to cracked products at conversion levels of 70-90%, was highest for catalysts containing 0.5 to 1.0 wt% of Pt. Selectivity was also dependent on the Ca concentration, {und viz} the catalyst acidity, and on the catalyst reduction temperature.

  1. Growth of Megaspherulites In a Rhyolitic Vitrophyre

    NASA Technical Reports Server (NTRS)

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


    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 respectively. Once diffusion reestablishes itself at the crystallization front, a new nucleation event occurs at the terminated tips of the fibril cones and a new cone begins to develop with a similar orientation (small angle branching) to the earlier cones. During crystallization, these fibril cones impinge upon each other, resulting in fibril cone-free areas. These cone-free areas consist of coarser, fine-grained phases, dominated by quartz, which crystallized from the melt as it accumulated between the crystallizing K-feldspar fibrils of the cones. The anhydrous nature of the disordered to ordered sanidine (orthoclase) and quartz, suggests that water in the vitrophyre moved ahead of the crystallization front, resulting in a water rich fluid being enriched in Si, K, Na, Mg, Ca, Sr, Ba, and Y. The clay layers associated with the megaspherulites are therefore, the result of the deuteric alteration between the fractionated water and the vitrophyre, as indicated by the presence of the minerals mordenite and montmorillonite. This silica rich fluid also resulted in the total silicification of the megaspherulites within the upper 3 m of the vitrophyre.

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

    SciTech Connect

    Waters, A.C.; Carroll, P.R. (eds.)


    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.

  3. Variations in authigenic mineralogy and sorptive zeolite abundance at Yucca Mountain, Nevada, based on studies of drill cores USW GU-3 and G-3

    SciTech Connect

    Vaniman, D.; Bish, D.; Broxton, D.; Byers, F.; Heiken, G.; Carlos, B.; Semarge, E.; Caporuscio, F.; Gooley, R.


    Drill Hole USW GU-3 was cored continuously from the surface to a depth of 2637.0 ft (803.8 m) beneath the central crest of Yucca Mountain. Drill Hole USW G-3 was cored continuously from 2625.4 ft (800.2 m) to 5030.8 ft (1533.4 m) nearby. Studies of the mineralogy and petrology of these core samples concentrate on the products of low-temperature diagenetic alteration; they indicate less alteration, and of lower grade, than is noted in any of the cored drill holes from farther north at Yucca Mountain. Relatively unstable primary phases such as glasses, tridymite, and cristobalite are preserved to greater depth. Clinoptilolite persists to greater depth, and authigenic albite, a relatively high-grade secondary mineral, does not occur. Calcite is rare, and mordenite is virtually absent, except for rare occurrences along fractures in the Crater Flat Tuff. Compositional zonation of zeolites is highly variable and poorly correlated with depth, and a clearly defined smectite-to-illite transition is lacking. Smectite interstratifications, poor in illite, indicate a maximum alteration temperature no greater than 40{sup 0}C at the bottom of USW G-3 (5031 ft or 1533 m). All these features contrast sharply with those of samples from the northern part of Yucca Mountain. In particular, the tuff of Calico Hills can not be relied upon as a zeolitized sorptive barrier throughout Yucca Mountain. However, four commonly zeolitized intervals are defined and traced across the exploration block at Yucca Mountain. Analysis of these intervals indicates that equivalent thicknesses of 100% sorptive zeolite range from 24 to 78 m at various localities below any proposed repository in the moderately to densely welded Topopah Spring unit and above the static water level. 26 references, 12 figures, 4 tables.

  4. Effect of modifier Pd metal on hydrocracking of polyaromatic compounds over Ni-loaded Y-type zeolite and its application as hydrodesulfurization catalysts

    SciTech Connect

    Wada, Takema; Murata, Satoru; Nomura, Masakatsu [Osaka Univ. (Japan)


    Coal tar obtained from coal carbonization is a treasure of polyaromatic hydrocarbons, where more than 400 kinds of aromatic compounds are found to be contained. The development of new catalysts being able to convert these aromatics into mono or diaromatic compounds is one of objectives for utilization of polyaromatics. Hydrocracking of polyaromatic compounds is believed to proceed via formation of terminal-naphthenic ring of starting aromatic compounds, followed by cleavage of the naphthenic ring to produce alkylated aromatic compounds which has less numbers of ring than starting aromatics. Accordingly, hydrogenation of aromatic rings and cracking of resulting naphthenic rings are key steps of hydrocracking reaction, so that dual functional catalysts such as metal-supported acid catalysts are considered to be one of the best catalysts. Zeolite has controlled pore structures and strong acidity enough to crack naphthenic rings, being characteristics in exchanging metal species with ease. We have been studying the hydrocracking of polyaromatic compounds over Ni-loaded zeolite catalysts (ZSM-5, mordenite, and Y-type) and found the fact that pore size of zeolite exerts an interesting effect on product distribution. We also conducted computer-simulation for diffusion phenomena of the polyaromatic hydrocarbons in the pore of these zeolites and found that diffusion ability of the substrate affects strongly the product distributions Recently we found that modifying of Ni-loaded Y-type zeolite by Pd-loading enhanced hydrocracking ability of the catalyst. In this report, we would like to refer to the results of both hydrocracking reaction of pyrene and hydrodesulfurization of dibenzothiophene using Pd-modified Ni-loaded Y-type zeolite.

  5. The heat capacity of hydrous cordierite above 295 K

    NASA Astrophysics Data System (ADS)

    Carey, J. William


    The heat capacity of synthetic hydrous cordierite (Mg2Al4Si5O18·nH2O) has been determined by differential scanning calorimetry (DSC) from 295 to 425 K as a function of H2O content. Six samples with H2O contents ranging from 0 to 0.82 per formula unit were examined. The partial molar heat capacity of H2O in cordierite over the measured temperature interval is independent of composition and temperature within experimental uncertainty and is equal to 43.3 ±0.8 J/mol/ K. This value exceeds the molar heat capacity of gaseous H2O by 9.7 J/mol/K, but is significantly smaller than the heat capacity of H2O in several zeolites and liquid H2O. A statistical-mechanical model of the heat capacity of adsorbed gas species (Barrer 1978) is used to extrapolate the heat capacity of hydrous cordierite to temperatures greater than 425 K. In this model, the heat capacity of hydrous cordierite (Crd·nH2O) is represented as follows: Cp(Crd · nH2O) = Cp(Crd)+ n{Cp(H2O, gas)+ R(gas constant)} (1) An examination of calorimetric data for hydrous beryl, analcime, mordenite, and clinoptilolite (Hemingway et al. 1986; Johnson et al. 1982, 1991, 1992) demonstrates the general applicability of the statistical-mechanical model for the extrapolation of heat capacity data of zeolitic minerals. The heat capacity data for cordierite are combined with the data of Carey and Navrotsky (1992) to obtain the molar enthalpy of formation and enthalpy of hydration of hydrous cordierite as a function of temperature.

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

    SciTech Connect

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


    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.

  7. Cation promotion effect in zeolite-supported F-T catalysts: Final report

    SciTech Connect

    Goodwin, J.G. Jr.; Oukaci, R.


    The present work was undertaken to investigate systematically the influence of Group IA neutralizing cations on CO hydrogenation over zeolite-supported ruthenium catalysts. These catalysts were prepared from NH/sub 4/Y, LiY, NaY, KY, RbY, CsY, NaX, KL, and Na-mordenite zeolites by ion exchange with ruthenium hexammine chloride. The nature of the group IA cations was found to have little effect on chemisorptive properties and on the activity and chain growth probability in CO hydrogenation on Ru. However, it was established that secondary acid-catalyzed reactions of the primary olefinic products from CO hydrogenation can play a major role in shaping product selectivity. Using model reactions such as olefin transformations on the zeolites without the metal, it was established that the strength of the acid sites is a strong function of the nature of the neutralizing alkali cations remaining in the zeolite. Acid site strength was found to decrease with molecular weight of the alkali cation used. This study established the bifunctional nature of the zeolite-supported F-T catalysts and its importance in CO hydrogenation. The results suggest that the catalyst selectivity can be controlled by varying the strength of the zeolite acid sites, the most important active centers for secondary reactions of the primary olefinic F-T products. Depending on the concentration and the strength of the acid sites, a function of the Si/Al ratio and the nature of the residual neutralizing cations, various competitive reaction paths can be observed for the transformation of olefinic compounds. These include isomerization, oligomerization, cracking, hydrogen transfer, etc. 67 figs., 32 tabs.

  8. Zeolitization of intracaldera sediments and rhyolitic rocks in the 1.25 Ma lake of Valles caldera, New Mexico, USA

    NASA Astrophysics Data System (ADS)

    Chipera, Steve J.; Goff, Fraser; Goff, Cathy J.; Fittipaldo, Melissa


    Quantitative X-ray diffraction analysis of about 80 rhyolite and associated lacustrine rocks has characterized previously unrecognized zeolitic alteration throughout the Valles caldera resurgent dome. The alteration assemblage consists primarily of smectite-clinoptilolite-mordenite-silica, which replaces groundmass and fills voids, especially in the tuffs and lacustrine rocks. Original rock textures are routinely preserved. Mineralization typically extends to depths of only a few tens of meters and resembles shallow "caldera-type zeolitization" as defined by Utada et al. [Utada, M., Shimizu, M., Ito, T., Inoue, A., 1999. Alteration of caldera-forming rocks related to the Sanzugawa volcanotectonic depression, northeast Honshu, Japan — with special reference to "caldera-type zeolitization." Resource Geol. Spec. Issue No. 20, 129-140]. Geology and 40Ar/ 39Ar dates limit the period of extensive zeolite growth to roughly the first 30 kyr after the current caldera formed (ca. 1.25 to 1.22 Ma). Zeolitic alteration was promoted by saturation of shallow rocks with alkaline lake water (a mixture of meteoric waters and degassed hydrothermal fluids) and by high thermal gradients caused by cooling of the underlying magma body and earliest post-caldera rhyolite eruptions. Zeolitic alteration of this type is not found in the later volcanic and lacustrine rocks of the caldera moat (? 0.8 Ma) suggesting that later lake waters were cooler and less alkaline. The shallow zeolitic alteration does not have characteristics resembling classic, alkaline lake zeolite deposits (no analcime, erionite, or chabazite) nor does it contain zeolites common in high-temperature hydrothermal systems (laumontite or wairakite). Although aerially extensive, the early zeolitic alteration does not form laterally continuous beds and are consequently, not of economic significance.

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

    SciTech Connect

    Suzuki, Y.; Kohyama, N.


    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.

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

    SciTech Connect

    WoldeGabriel, G.


    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.

  11. Thermal and catalytic cracking of tars and tar constituents from coal-gasification processes. Final report. [Synthetic zeolites (Linde LZ-Y82, Norton Zeolon 900-H, Davison 13-X, faujasite), natural zeolite (chabazite)

    SciTech Connect

    Wen, W.Y.


    The objective of this program is to screen catalysts and determine operating conditions for maximizing gas and char production from the pyrolysis of coal gasification tars. The product yields from cracking a bituminous coal tar in a fixed-bed reactor were determined at various temperatures in the presence and absence of some packing materials. Synthetic zeolites, Linde LZ-Y82, Norton Zeolon 900-H (mordenite), Davison 13-X, and ultra-stable faujasite (H-Y), as well as a natural zeolite, chabazite, showed strong catalytic activity. In contrast, molecular sieves 5-A and natural erionite having smaller pore diameters were found to be much less active. Clay minerals such as kaolinite, montmorillonite and Kieselguhr exhibited catalytic activities which were similar to those of the zeolites with small pore sizes, but they were still far more effective than quartz particles. Based on the assumption of first-order kinetics, the activation energies for the tar conversion were evaluated for several packing materials. It was found that the zeolite LZ-Y82 was remarkably effective in converting tar to chars and gases in the temperature range of 350 to 500/sup 0/C, although this effectiveness decreased very rapidly with a continuous tar feed carried by an inert gas. Among the factors involved for catalytic effectiveness are (1) the effective pore size greater than about 0.7 nm (or 7A), (2) large internal surface area accessible to the tar vapor, and (3) large number of strongly acidic sites. 22 references, 6 figures, 22 tables.

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

    SciTech Connect

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


    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.

  13. Electron transfer reactions in microporous solids

    SciTech Connect

    Mallouk, T.E.


    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.

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

    SciTech Connect

    Mallouk, T.E.


    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.

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

    SciTech Connect

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


    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.

  16. Mineral Resources of the Warm Springs Wilderness Study Area, Mohave County, Arizona

    USGS Publications Warehouse

    Gray, Floyd; Jachens, Robert C.; Miller, Robert J.; Turner, Robert L.; Knepper, Daniel H.; Pitkin, James A.; Keith, William J.; Mariano, John; Jones, Stephanie L.; Korzeb, Stanley L.


    At the request of the U.S. Bureau of Land Management, approximately 113,500 acres of the Warm Springs Wilderness Study Area (AZ-020-028/029) were evaluated for mineral resources and mineral resource potential. In this report, the area studied is referred to as the 'wilderness study area' or 'study area'; any reference to the Warm Springs Wilderness Study Area refers only to that part of the wilderness study area for which a mineral survey was requested. This study area is located in west-central Arizona. The U.S. Geological Survey and the U.S. Bureau of Mines conducted geological, geochemical, and geophysical surveys to appraise the identified mineral resources (known) and assess the mineral resource potential (undiscovered) of the study area. fieldwork for this report was carried out largely in 1986-1989. There is a 1-million short ton indicated subeconomic resource of clinoptilolite-mordenite zeolite and an additional inferred resource of 2 million short tons near McHeffy Butte, approximately 2 miles west of the study area. A perlite deposit in the southeast corner of the study area contains an inferred subeconomic resource totaling 13 million short tons. An inferred subeconomic resource of gold in 225 short tons of quartz having a grade of 0.01 8 troy ounces per short ton is present at the Cook mine, 0.5 miles west of the study area. The northwestern part of the Warm Springs Wilderness Study Area has high mineral resource potential for gold and silver. The south-central part of the study area has one area of moderate and one area north of this south-central part has low mineral resource potential for gold and silver in and near Warm Springs Canyon; the mineral resource potential for gold is also moderate in three small areas in the southern part and one area in the northeastern part of the study area. The mineral resource potential for zeolite is high for the area surrounding the McHeffy Butte prospect and for one area in the southern part of the study area. Two areas inside the south and southeast boundaries of the study area have high mineral resource potential for perlite. The potential for ka: olinite resources is moderate in two areas in the southern part of the study area. The southern part of the study area has low resource potential for perlite and zeolite. Geothermal energy resource potential of the study area is low. The study area has no resource potential for oil and gas.

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

    NASA Astrophysics Data System (ADS)

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


    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 vitro and in vivo studies have shown its toxic and carcinogenic properties; 2) the carcinogenic properties of erionite have been demonstrated, and erionite has been associated with a mesothelioma epidemic in Anatolia, Turkey. Erionite is also widespread in areas of north central USA, where it is contained in gravel paving stone, and is cause for concern due to increased commercial traffic. Numerous studies have shown that non-regulated fibrous materials pose similar health hazards to regulated "asbestos". An increase in human activities in areas where these fibrous minerals are present, such as in surficial rock and soil, will result in the generation of airborne dust, exposing people to carcinogenic fibers. The current limited regulation leads people to believe that only the six mineral fibers referred to as "asbestos" are dangerous. We propose that fibrous minerals should be regulated as a single group, as they have similar deleterious effects on the human body. Regulations would be simplified and more effective if they embrace all carcinogenic fibrous minerals.

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

    SciTech Connect

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


    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-ray single-crystal analyses, in conjunction with high pressure differential pair distribution function (d-PDF) studies aimed to identify preferential sites in the pores, and improve MOFs robustness. Furthermore, durability studies on the iodine loaded MOFs and subsequent waste forms include thermal analyses, SEM/EDS elemental mapping, and leach-durability testing. We anticipate for this in-depth analysis to further aid the design of advanced materials, capable to address major hallmarks: safe capture, stability and durability over extended timeframes.

  19. 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.


    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, carboxylic, sulfhydryl, etc.); thus, the FT-IR and Raman spectra are the same as those of solid Cys.

  20. 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.


    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.

  1. 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.


    The Bigadiç, Emet and Kirka lacustrine basins of western Turkey may be considered as Tibet-type graben structures that were developed during the Miocene within the Izmir-Ankara suture zone complex. The volcanic-sedimentary successions of these basins are made up of mudstone, carbonate (limestone and dolomite) and detrital rocks, and also of crystal or vitric tuffs about 135 to 200 m thick. The Degirmenli (Bigadiç), Emirler (Bigadiç) Köpenez (Emet) and Karaören (Kirka) tuffs constituting the zeolite deposits are situated beneath four borate deposits (colemanite, ulexite, borax). The most abundant diagenetic silicate minerals are K- and Ca-clinoptilolites in the zeolite deposits, and Li-rich trioctahedral smectites (stevensite, saponite and hectorite) and K-feldspar in the borate deposits. In the Degirmenli, Emirler, Köpenez and Karaören deposits, the following diagenetic facies were developed from rhyolitic glasses rich in K and poor in Na: (glass+smectite), (K-clinoptilolite+opal-CT), (Ca-clinoptilolite+K-feldspar±analcime± quartz) and (K-feldspar+analcime+quartz). K-feldspar which is also rarely associated with phillipsite (Karaören) and heulandite (Degirmenli and Karaören), succeeds clinoptilolite and precedes analcime in these diagenetic facies where dioctahedral smectites, opal-CT and quartz are the latest minerals. No diagenetic transformations exist between clinoptilolite, K-feldspar and analcime that were formed directly from glass. The lateral facies distributions resulted from the differences in salinity and pH of pore water trapped during deposition of the tuffs, but vertical distributions in vitric tuffs seem to have been controlled by the glass/liquid ratio of the reacting system and the permeability or diffusion rate of alkali elements. The Bigadiç, Emet and Kirka zeolite deposits which were formed in saline basins rich in Ca and Mg ions, show similar chemical changes, i.e. loss of alkalis and gain in alkaline-earth elements that have taken 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.


    SciTech Connect



    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 system was reconfigured to enable testing of the baseline HLW or LAW off-gas trains to perform off-gas emissions testing with both LAW and HLW simulants in the present work. During 2002 and 2003, many of these off-gas components were tested individually and in an integrated manner with the DM1200 Pilot Melter. Data from these tests are being used to support engineering design confirmation and to provide data to support air permitting activities. In fiscal year 2004, the WTP Project was directed by the Office of River Protection (ORP) to comply with Environmental Protection Agency (EPA) Maximum Achievable Control Technology (MACT) requirements for organics. This requires that the combined melter and off-gas system have destruction and removal efficiency (DRE) of >99.99% for principal organic dangerous constituents (PODCs). In order to provide confidence that the melter and off-gas system are able to achieve the required DRE, testing has been directed with both LAW and HLW feeds. The tests included both 'normal' and 'challenge' WTP melter conditions in order to obtain data for the potential range of operating conditions for the WTP melters and off-gas components. The WTP Project, Washington State Department of Ecology, and ORP have agreed that naphthalene will be used for testing to represent semi-volatile organics and allyl alcohol will be used to represent volatile organics. Testing was also performed to determine emissions of halides, metals, products of incomplete combustion (PICs), dioxins, furans, coplanar PCBs, total hydrocarbons, and COX and NOX, as well as the particle size distribution (PSD) of particulate matter discharged at the end of the off-gas train. A description of the melter test requirements and analytical methods used is provided in the Test Plan for this work. Test Exceptions were subsequently issued which changed the TCO catalyst, added total organic emissions (TOE) to exhaust sampling schedule, and allowing modification of the test conditions in response to attainable plenum temperatures as well as temperature increases in the sulfur impr

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

    NASA Astrophysics Data System (ADS)

    Gianni, Areti; Zacharias, Ierotheos


    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 calculated equal to 123.1 10-3 mg/g S2-. Zeolite removal capacity varied by about 10% as the solution's salinity varied from 0 to 35‰. This study emphasizes in the zeolite ability to remove dissolved sulfides from aqueous solutions. According to literature, natural zeolite is particularly effective in removing ammonium from aquatic solutions, while due to its negative charge zeolite doesn't adsorb phosphate ions. However, in the presence of cations (Ca+2, Na+, K+) in the aquatic solution it turns to the appropriate substrate for the formed phosphate salts. In conclusion, zeolite is a natural inert material, capable to remove from aqueous solutions forms of nitrogen, phosphorus and sulfur. Due to this ability zeolite could play a key role, in eutrophic/anoxic environments restoration efforts, since PO43-, NH4+ and H2S constitute the three aspects of the problem called anoxic basins' internal load.

  4. 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.


    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 linked to erionite in Italy is extremely scarce: INAIL, through its database of occupational diseases, can provide essential information for epidemiological research. An effective risk assessment in Italy will require coordinated actions from government agencies, local health authorities, Universities and research centers, in order to record the actual presence of fibrous zeolites, recognizing mineral species and quantifying their abundance in rock deposits. The different geological conditions through time of volcanic deposits will be compared with an updated "database" on the physical-chemical-geological conditions of formation of zeolites. In sites where the presence of fibrous zeolites has been validated by laboratory tests, we will proceed with accurate field surveys and sampling campaigns, in order to determine detailed geological-stratigraphic and structural features, and resolving precisely the thickness, areal extent and volume of lithostratigraphic units containing these minerals. These data will be entered into a GIS to produce a result that can be used immediately and in the long-period by research institutes, local authorities and regional agencies for environmental protection. In sites where the presence of hazardous fibrous minerals has been validated, we will plan airborne fibers sampling campaigns, and we will assess the extent of airborne dispersion produced by natural agents and by man activity. In the case that these sites host active mining or quarrying activities, we will quantify the airborne fibers contamination at workplaces and propose measures for environmental risk mitigation.

  5. Development of Composite Adsorbents for LLW Treatment and Their Adsorption Properties for Cs and Sr - 13127

    SciTech Connect

    Susa, Shunsuke; Mimura, Hitoshi [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-2, Sendai, 980-8579 (Japan)] [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-2, Sendai, 980-8579 (Japan); Ito, Yoshiyuki; Saito, Yasuo [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, 2-4 Shirakata Shirone, Naka-gun, Ibaraki, 319-1195 (Japan)] [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, 2-4 Shirakata Shirone, Naka-gun, Ibaraki, 319-1195 (Japan)


    In this study, the composite adsorbents (KCoFC-NM (NM: natural mordenite), KCoFC-SG (SG: porous silica gel), AMP-SG and so on) were prepared by impregnation-precipitation methods. As for the distribution properties, the largest K{sub d,Cs} value of 3.8 x 10{sup 4} cm{sup 3}/g was obtained for KCoFC-SG (Davi.) composite. KCoFC-SG (NH, MB5D) and T-KCFC also had relatively large K{sub d,Cs} values above 1.0 x 10{sup 4} cm{sup 3}/g. The uptake rate of Cs{sup +} ions was examined by batch method. KCoFC-SG (NH, MB5D) and AMP-SG (Davi.) had relatively large uptake rate of Cs{sup +}, and the uptake attained equilibrium within 1 h. The maximum uptake capacity of Cs{sup +} ions was estimated to be above 0.5 mmol/g for KCoFC-NM and KCoFC-CP composites. KCoFC-X composite had a relatively large uptake capacity of Cs{sup +} ions (0.23 mmol/g > 0.17 mmol/g (T-KCFC)) and this composite also had a selectivity towards Sr{sup 2+} ions; KCoFC-X is effective adsorbent for both Cs{sup +} and Sr{sup 2+} ions. The largest value of K{sub d,Sr} was estimated to be 218 cm{sup 3}/g for titanic acid-PAN. Titanic acid-PAN had the largest uptake rate of Sr{sup 2+} ions, and the uptake attained equilibrium within 8 h. Adsorbability of other nuclides was further examined by batch method. All adsorbents had adsorbability for Rb{sup +} and RuNO{sup 3+} ions. KCoFC-SG (NH), KCoFC-CP and T-KCFC had higher selectivity towards Cs{sup +} than other adsorbents; these adsorbents had adsorbability to Cs{sup +} ions even in the presence of Ba{sup 2+}, Ca{sup 2+} and Mg{sup 2+} ions. The separation factor of K{sub d,Sr}/K{sub d,Ba} for titanic acid-PAN was about 1, indicating that the K{sub d,Sr} for titanic acid-PAN tends to decrease with Ba{sup 2+} concentration. As for the breakthrough properties, the largest 5 % breakpoint and 5 % breakthrough capacity of Cs{sup +} ions were estimated to be 47.1 cm{sup 3} and 0.07 mmol/g for the column of KCoFC-SG (NH), respectively. The order of 5 % breakthrough capacity of Cs{sup +} is as follows; KCoFC-SG (NH) > KCoFC-NM > KCoFC-SG (Q-10) > T-KCFC > KCoFC-X > KCoFC-CP. From the results of batch and column experiments, the composite adsorbent of KCoFC-SG (NH) was effective for the uptake of Cs{sup +} ions, and KCoFC-X composite was useful for the uptake of both Cs{sup +} and Sr{sup 2+} ions. The estimation of irradiation stability and the uptake properties using the actual wastes are further essential for the practical operation. (authors)

  6. Hanford Site Secondary Waste Roadmap

    SciTech Connect

    Westsik, Joseph H.


    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 performance requirements, waste composition, preliminary waste form screening, waste form development, process design and support, and validation. The regulatory and performance requirements activity will provide the secondary waste-form performance requirements. The waste-composition activity will provide workable ranges of secondary waste compositions and formulations for simulants and surrogates. Preliminary waste form screening will identify candidate waste forms for immobilizing the secondary wastes. The waste form development activity will mature the waste forms, leading to a selected waste form(s) with a defensible understanding of the long-term release rate and input into the critical decision process for a secondary waste treatment process/facility. The process and design support activity will provide a reliable process flowsheet and input to support a robust facility design. The validation effort will confirm that the selected waste form meets regulatory requirements. The final outcome of the implementation of the secondary waste roadmap is the compliant, effective, timely, and cost-effective disposal of the secondary wastes. The work necessary to address the programmatic, regulatory, and technical risks and uncertainties identified through the Secondary Waste Roadmap Workshop are assembled into several program needs elements. Programmatic/Regulatory needs include: • Select and deploy Hanford tank waste supplemental treatment technology • Provide treatment capability for secondary waste streams from tank waste treatment • Develop consensus on secondary waste form acceptance. Technology needs include: • Define secondary waste composition ranges and uncertainties • Identify and develop waste forms for secondary waste immobilization and disposal • Develop test methods to characterize secondary waste form performance. Details for each of these program elements are provided.

  7. 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.


    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. Variation is observed in the crystal size (close to 1 mm down to 10 um) and content (close to 50% to aphyric) of different tephra layers. For correlation of tephra layers with no glass, precisely measured K content of sanidine, along with the range of Ba concentration has proved to be most useful, although this criteria is more robust when suggesting non-correlations, because there appear to be instances where different eruptions have identical sanidine composition. 40Ar/39Ar age determinations on sanidine crystals reveal a large age range in tephra layers from the Lake Mead sedimentary basin, with the oldest tephra erupted at 22.88×0.02 Ma and the youngest at 12.93×0.02. Other tephra have ages of 13.20×0.04, 13.43×0.02, 14.20×0.05, 14.62×0.01, 15.09×0.02, 15.35×0.06, 15.67×0.07, 16.29×0.11, and 18.41×0.04. The chronology, geochemistry and coarse grain size of many of the tephra layers suggest derivation from either the Southwest Nevada Volcanic Field or the Caliente Caldera area. The tephra erupted at 12.93×0.02 is chronologically and geochemically similar to the very large Topopah Tuff eruption, and the 18.41×0.04 tephra may be related to the Caliente Caldera Hiko Canyon/Racer Canyon events. However, a set of finer grained, Fe-rich and/or anorthoclase-bearing tephra layers may have been erupted further afield, likely being related to Miocene Yellowstone plume track volcanism.