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1

Krypton retention on solid adsorbents. [Activated alumina; hydrogen mordenite, silver mordenite, sodium mordenite, cerium mordenite-H, cerium mordenite-Na, potassium mordenite-H, potassium mordenite-Na  

SciTech Connect

An experimental laboratory program was conducted to develop economical solid adsorbents for the retention of krypton from a dissolver off-gas stream. The study indicates that a solid adsorbent system is feasible and competitive with other developing systems which utilize fluorocarbon absorption nd cryogenic distillation. This technology may have potential applications not only in nuclear fuel reprocessing plants, but also in nuclear reactors and in environmental monitoring. Of the 13 prospective adsorbents evaluated with respect to adsorption capacity and cost, the commercially available hydrogen mordenite was the most cost-effective material at subambient temperatures (-40/sup 0/ to -80/sup 0/C). Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite.

Monson, P.R. Jr.

1982-01-01

2

Characterization of nickel loaded mordenite catalysts by temperature programmed reduction  

Microsoft Academic Search

Temperature programmed reduction (TPR) has been used to study the redox behavior of Ni(II) ions in nickel sodium mordenite (NiNaM) and decationated nickel mordenite (NiHM). The TPR profiles suggest that Ni(II) ions occupy nonequivalent sites with different cooridination states in the mordenite. The reducibility of Ni(II) depends strongly on the zeolite acidity.

Z. Popova; R. Dimitrova; Chr Dimitrova; G. Wendt

1989-01-01

3

Occurrence of Clinoptilolite and Mordenite in Tertiary Calc-Alkaline Pyroclastites from Sardinia (Italy)  

Microsoft Academic Search

Abstrae~Clinopti lolite and mordenite occur as diagenetic products of medium-grained, moderately welded and poorly sorted pyroclastic flows belonging to the Tertiary calc-alkaline volcanism of Sardinia. Both clinoptilolite and mordenite occur within pyroclastic flows of the same stratigraphic unit. Mordenite frequently occurs in the late volcanic sequences from Anglona area (northern Sardinia). Textural features indicate that zeolites are products of glass

Maria R. Ghiara; CARMELA PETTI; ENRICO FRANCO; I ROBERTO LONIS; SANTINA LUXORO; LUCIO GNAZZO

1999-01-01

4

Growth mechanism of a preferentially oriented mordenite membrane  

PubMed Central

A preferentially oriented mordenite membrane was successfully prepared on a seeded porous ?-alumina support. Characterization results of XRD (X-ray diffractometer) and FE-SEM (field emission scanning electron microscope) revealed that evolutionary selection might predominantly contribute to the formation of the sharply oriented mordenite membrane. The necessary conditions under which evolutionary selection occurs are: (a) the number density of nuclei on the support surface should be high enough at the early stage; (b) the crystals should grow fastest along one direction; and (c) the zeolite layer should proceed via the successive growth of the crystals nucleated on the support surface instead of the accumulation of the crystals formed in the bulk solution.

Li, Gang; Lin, Rui-sen; Kikuchi, Eiichi; Matsukata, Masahiko

2005-01-01

5

Selective hydrogenation of nitrate in water over Cu–Pd\\/mordenite  

Microsoft Academic Search

Hydrogenation of nitrate (NO3?) in water has been investigated by using Cu–Pd exchanged zeolites in a gas–liquid co-current flow system. Cu–Pd\\/mordenites prepared by ion-exchange at 383K were highly selective for the hydrogenation of NO3? with H2 to N2 and N2O at 278–333K. Among Cu–Pd\\/mordenites with various Cu\\/Pd ratios and loading amounts of metal, 1.2wt.% Cu–0.5wt.% Pd\\/mordenite (Cu\\/Pd=4) were shown to

Kyosuke Nakamura; Yasuyuki Yoshida; Ikkou Mikami; Toshio Okuhara

2006-01-01

6

Recycle of iodine-loaded silver mordenite by hydrogen reduction  

SciTech Connect

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.

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

1982-11-01

7

Characterization of Cu Mordenite deNOx Catalysts at Variable Si/Al Ratios, by NMR, TPD and Optical Spectroscopy  

NASA Astrophysics Data System (ADS)

Cu mordenite is an effective catalyst for nitrogen oxide removal (deNOx), which is readily produced from H mordenite at various silica-to-alumina (Si/Al) ratios by ion exchange. We have characterized a set of H and Cu mordenite catalysts prepared from material originally supplied by the TOSOH Corp. (Japan), using NMR, TPD and optical Diffuse Reflectance Spectroscopy. The nuclei observed in NMR were Silicon-29, Aluminum-27 and protons. Resulst show strong effects of Si/Al ratio, upon both framework and extra-framework structures of the mordenites. Information about the state of the Cu ion in the catalysts will be reviewed.

Marzke, Robert F.; Petranovskii, Vitalii P.; Bogdanchikova, Nina E.

2002-03-01

8

Organic iodine removal from simulated dissolver off-gas systems utilizing silver-exchanged mordenite  

SciTech Connect

The removal of methyl iodide by adsorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The adsorption of methyl iodide on silver mordenite was examined for the effect of NO/sub x/, humidity, iodine concentration, filter temperature, silver loadings and filter pretreatment. The highest iodine loading achieved in these tests was 142 mg CH/sub 3/I per g of substrate on fully exchanged zeolite, approximately the same as elemental iodine loadings. A filter using fully exchanged silver mordenite operating at 200/sup 0/C obtained higher iodine loadings than a similar filter operating at 150/sup 0/C. Pretreatment of the sorbent bed with hydrogen rather than dry air, at a temperature of 200/sup 0/C, also improved the loading. Variations in the methyl iodide concentration had minimal effects on the overall loading. Filters exposed to moist air streams attained higher loadings than those in contact with dry air. Partially exchanged silver mordenite achieved higher silver utilizations than the fully exchanged material. The partially exchanged mordenite also achieved higher loadings at 200/sup 0/C than at 250/sup 0/C. The iodine loaded onto these beds was not stripped at 500/sup 0/C by either 4.5% hydrogen or 100% hydrogen; however, the iodine could be removed by air at 500/sup 0/C, and the bed could be reloaded. A study of the regeneration characteristics of fully exchanged silver mordenite indicates limited adsorbent capacity after complete removal of the iodine with 4.5% hydrogen in the regeneration gas stream at 500/sup 0/C. The loss of adsorbent capacity is much higher for silver mordenite regenerated in a stainless steel filter housing than in a glass filter housing.

Jubin, R.T.

1981-01-01

9

Spectroscopy and redox chemistry of copper in mordenite.  

PubMed

Copper-containing zeolites, such as mordenite (MOR), have recently gained increased attention as a consequence of their catalytic potential. While the preferred copper loadings in these catalytic studies are generally high, the literature lacks appropriate spectroscopic and structural information on such Cu-rich zeolite samples. Higher copper loadings increase the complexity of the copper identity and their location in the zeolite host, but they also provide the opportunity to create novel Cu sites, which are perhaps energetically less favorable, but possibly more reactive and more suitable for catalysis. In order to address the different role of each Cu site in catalysis, we here report a combined electron paramagnetic resonance (EPR), UV/Vis-NIR and temperature-programmed reduction (TPR) study on highly copper-loaded MOR. Highly resolved diffuse reflectance (DR) spectra of the CuMOR samples were obtained due to the increased copper loading, allowing the differentiation of two isolated mononuclear Cu(2+) sites and the unambiguous correlation with extensively reported features in the EPR spectrum. Ligand field theory is applied together with earlier suggested theoretical calculations to determine their coordination chemistry and location within the zeolite matrix, and the theoretical analysis further allowed us to define factors governing their redox behavior. In addition to monomeric species, an EPR-silent, possibly dimeric, copper site is present in accordance with its charge transfer absorption feature at 22200 cm(-1), and quantified with TPR. Its full description and true location in MOR is currently being investigated. PMID:24399800

Vanelderen, Pieter; Vancauwenbergh, Julie; Tsai, Ming-Li; Hadt, Ryan G; Solomon, Edward I; Schoonheydt, Robert A; Sels, Bert F

2014-01-13

10

XPS characterization of silver exchanged ETS-10 and mordenite molecular sieves.  

PubMed

Silver exchanged molecular sieves ETS-10 (Ag-ETS-10) and mordenite (Ag-mordenite) were dehydrated under vacuum at temperatures between 100 degrees C-350 degrees C. Changes in the state of the silver were studied using X-ray photoelectron spectroscopy (XPS). Silver cations in titanosilicate Ag-ETS-10 are fully reduced to Ag(0) at temperatures as low as 150 degrees C. The characteristic features of the XPS spectrum of silver in this Ag-ETS-10 species correspond to only metallic silver. The signal for metallic silver is not observed in the XPS spectrum of aluminosilicate Ag-mordenite, indicating that silver cations are not reduced, even after heating to 350 degrees C. PMID:19452980

Anson, A; Maham, Y; Lin, C C H; Kuznicki, T M; Kuznicki, S M

2009-05-01

11

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.

2014-01-01

12

Growth and characterization of ZnS and ZnCdS nanoclusters in mordenite zeolite host  

Microsoft Academic Search

The growth of semiconductor nanoclusters of ZnS and the ternary ZnCdS system embedded in synthetic mordenites by ionic exchange using different mixtures of CdCl2 and ZnCl2 as starting sources, followed by treatment in hydrogen sulphide flow, is reported. Compositional, morphological and structural studies were realized by XRD, SEM, TEM and energy dispersive spectroscopy (EDS). XRD shows well-crystallized mordenite and the

O. Raymond; H. Villavicencio; V. Petranovskii; J. M. Siqueiros

2003-01-01

13

Liquid-phase degradation of polyethylene wax over mordenite catalysts with different Si\\/Al molar ratios  

Microsoft Academic Search

The catalytic liquid-phase degradation of polyethylene wax into fuel oil was studied using mordenite catalysts with various Si\\/Al molar ratios prepared by dealumination. The total yield of gas and liquid products showed a volcano plot along the Si\\/Al molar ratio of mordenite. No significant change was observed in the composition of the liquid product for all catalysts used in this

Young San You; Jong-Seob Shim; Jong-Ho Kim; Gon Seo

1999-01-01

14

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

NASA Astrophysics Data System (ADS)

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

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

15

Removal of Copper (II) Ions from Aqueous Solutions using Na?mordenite  

Microsoft Academic Search

The potential to remove copper (II) ions from aqueous solutions using Na?mordenite, a common zeolite mineral, was thoroughly investigated. The effects of relevant parameters solution pH, adsorbent dose, ionic strength, and temperature on copper (II) adsorption capacity were examined. The sorption data followed the Langmuir, Freundlich, and Dubinin?Radushkevich (D?R) isotherms. The maximum sorption capacity was found to be 10.69 mg\\/g at

Cheng Sun

2007-01-01

16

Crystallization and morphology of mordenite zeolite influenced by various parameters in organic-free synthesis  

SciTech Connect

Research highlights: {yields} Seed, gel composition and silicon source affect the crystallization process of MOR. {yields} Seed, gel composition and silicon source influence the morphology of MOR. {yields} Low silica concentration results in MOR with high c/b aspect ratio. {yields} Novel nano fiber-like MOR with c/b aspect ratio of 89 was organic-free synthesized. {yields} The morphology of MOR influences its mesopore property and thermal stability. -- Abstract: A series of mordenite zeolites with different morphologies were synthesized via a facile organic-free hydrothermal route, and characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence spectrometer and N{sub 2} adsorption-desorption techniques. Influences of synthetic parameters, including seed crystal, silicon precursor, SiO{sub 2}/Al{sub 2}O{sub 3}, Na{sub 2}O/SiO{sub 2} and H{sub 2}O/SiO{sub 2}, on mordenite crystallization were investigated systematically. It was found that mordenite zeolites with various morphologies, such as fiber-like, rod-like, prism-like and needle-like ones could be synthesized in control. Especially, novel nano fiber-like MOR crystals with high c/b aspect ratio were prepared from low silica concentration system, which was manipulated by using small initial SiO{sub 2}/Al{sub 2}O{sub 3} ratio, large H{sub 2}O/SiO{sub 2} and silicon source with slow dissolution rate. Moreover, mordenite samples with various morphologies exhibited different mesopore property and thermal stability.

Zhang, Ling [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian P.O. Box 110, 116023 (China) [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian P.O. Box 110, 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Xie, Sujuan; Xin, Wenjie; Li, Xiujie; Liu, Shenglin [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian P.O. Box 110, 116023 (China)] [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian P.O. Box 110, 116023 (China); Xu, Longya, E-mail: lyxu@dicp.ac.cn [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian P.O. Box 110, 116023 (China)] [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian P.O. Box 110, 116023 (China)

2011-06-15

17

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

Microsoft Academic Search

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

M. A. Hernáandez; L. Corona; F. Rojas

2000-01-01

18

Comparison of the ion exchange uptake of ammonium ion onto New Zealand clinoptilolite and mordenite  

Microsoft Academic Search

In this study the uptake performances of the naturally occurring zeolite, clinoptilolite, and of New Zealand mordenite are compared. The uptake of fully ionised ammonium ion from aqueous solutions in the concentration range 0–200mg\\/l on to these two materials was compared. The influence of other cations present in water upon the ammonia uptake was also determined. The cations studied were

L. R. Weatherley; N. D. Miladinovic

2004-01-01

19

Organic iodine removal from simulated dissolver off-gas streams using silver-exchanged mordenite  

SciTech Connect

The removal of methyl iodide by absorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The methyl iodide absorption of silver mordenite was examined for the effects of NO/sub x/, humidity, iodine concentration, filter temperature, and filter pretreatment. The highest iodine loading achieved in these tests has been 34 mg CH/sub 3/I per g of substrate, approximately five times less than the elemental iodine loadings. Results indicate that a filter operating at a temperature of 150/sup 0/C obtained higher iodine loadings than a similar filter operating at 100/sup 0/C. Pretreatment of the sorbent bed with hydrogen, rather than dry air, at a temperature of 200/sup 0/C also improved the loading. Variations in the methyl iodide concentration had minimal effects on the overall loading. Filters exposed to moist air streams attained higher loadings than those in contact with dry air. A study of the regeneration characteristics of silver mordenite indicates limited adsorbent capacity after complete removal of the iodine with 4% hydrogen in the regeneration gas stream at 500/sup 0/C. 9 figures.

Jubin, R.T.

1980-01-01

20

Location of MTBE and toluene in the channel system of the zeolite mordenite: Adsorption and host-guest interactions  

SciTech Connect

This paper reports a study of the location of Methyl Tertiary Butyl Ether (MTBE) and toluene molecules adsorbed in the pores of the organophylic zeolite mordenite from an aqueous solution. The presence of these organic molecules in the zeolite channels was revealed by structure refinement performed by the Rietveld method. About 3 molecules of MTBE and 3.6 molecules of toluene per unit cell were incorporated into the cavities of mordenite, representing 75% and 80% of the total absorption capacity of this zeolite. In both cases a water molecule was localized inside the side pocket of mordenite. The saturation capacity determined by the adsorption isotherms, obtained by batch experiments, and the weight loss given by thermogravimetric (TG) analyses were in very good agreement with these values. The interatomic distances obtained after the structural refinements suggest MTBE could be connected to the framework through a water molecule, while toluene could be bonded to framework oxygen atoms. The rapid and high adsorption of these hydrocarbons into the organophylic mordenite zeolite makes this cheap and environmental friendly material a suitable candidate for the removal of these pollutants from water. - graphical abstract: Location of MTBE (a) and toluene (b) in mordenite channels (projection along the [001] direction). Highlights: Black-Right-Pointing-Pointer We investigated the MTBE and toluene adsorption process into an organophilic zeolite mordenite. Black-Right-Pointing-Pointer The presence of MTBE and toluene in mordenite was determined by X-ray diffraction studies. Black-Right-Pointing-Pointer About 3 molecules of MTBE and 3.6 molecules of toluene per unit cell were incorporated into the zeolite cavities. Black-Right-Pointing-Pointer MTBE is connected to the framework through a water molecule. Black-Right-Pointing-Pointer Toluene is directly bonded to framework oxygen atoms.

Arletti, Rossella, E-mail: rossella.arletti@unito.it [Department of Earth Sciences, University of Torino Via Valperga Caluso 35, I-10125, Torino (Italy)] [Department of Earth Sciences, University of Torino Via Valperga Caluso 35, I-10125, Torino (Italy); Martucci, Annalisa; Alberti, Alberto [Department of Earth Sciences, University of Ferrara, Via G. Saragat 1, I-44100, Ferrara (Italy)] [Department of Earth Sciences, University of Ferrara, Via G. Saragat 1, I-44100, Ferrara (Italy); Pasti, Luisa; Nassi, Marianna [Department of Chemistry, University of Ferrara, Via L. Borsari 26, I-44100 Ferrara (Italy)] [Department of Chemistry, University of Ferrara, Via L. Borsari 26, I-44100 Ferrara (Italy); Bagatin, Roberto [Research Centre for Non-Conventional Energy-Istituto ENI Donegani, Environmental Technologies, Via Fauser 4, I-28100 Novara (Italy)] [Research Centre for Non-Conventional Energy-Istituto ENI Donegani, Environmental Technologies, Via Fauser 4, I-28100 Novara (Italy)

2012-10-15

21

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

PubMed

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

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

2010-08-01

22

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

SciTech Connect

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

Kirchner, J.G. (Illinois State Univ., Normal (United States))

1991-10-01

23

Effect of cation exchange on hydrogen adsorption property of mordenite for isotope separation  

NASA Astrophysics Data System (ADS)

Zeolite easily exchanges its cation to another. As a result, pore size changes easily. Cation-exchanged mordenite type zeolite (MOR) has been reported to have comparatively good isotope separation capability at temperatures higher than 77 K. However, correlations between adsorption capacities, adsorption rate, cation variety, and cation exchange ratio have not been clearly indicated. In this work, the cation (Na+) of synthetic mordenite type zeolite (Na-MOR) was exchanged by alkaline metal ion or alkaline earth ion (e.g., Li+, K+, Mg2+ and Ca2+). Then, adsorption capacities of H2 and D2 were investigated at 77 K, 159 K, 175 K and 195 K. Adsorption capacities on Li-MOR and Ca-MOR became larger than that of Na-MOR at a low-pressure range, while that of K-MOR became smaller. Micro-pore size indicated that only K-MOR was clearly shifting to smaller size. In the case of alkaline metal, cations with lower atomic numbers may lead to increased adsorption capacities.

Kawamura, Yoshinori; Iwai, Yasunori; Munakata, Kenzo; Yamanishi, Toshihiko

2013-11-01

24

Effect of Change in Sign of the Selectivity in the Ion-Exchange Adsorption of Cobalt by Mordenite and Clinoptilolite  

Microsoft Academic Search

The selectivity sign of Na-zeolites relative to cobalt cations changes upon ion exchange above 11% in the case of mordenite and 16% in the case of clinoptilolite. The extent of exchange, at which the change in the selectivity sign is observed, was found to be related to the nature of the doubly-charged cations and type of zeolite.

V. I. Starosta; F. M. Bobonich; I. S. Balog

2001-01-01

25

Ammonia IRMS-TPD study on the distribution of acid sites in mordenite.  

PubMed

Using an IRMS-TPD (temperature programmed desorption) of ammonia, we studied the nature, strength, crystallographic location, and distribution of acid sites of mordenite. In this method, infrared spectroscopy (IR) and mass spectroscopy (MS) work together to follow the thermal behavior of adsorbed and desorbed ammonia, respectively; therefore, adsorbed species were identified, and their thermal behavior was directly connected with the desorption of ammonia during an elevation of temperature. IR-measured TPD of the NH4(+) cation was similar to MS-measured TPD, thus showing the nature of Brønsted acidity. From the behavior of OH bands, it was found that the Brønsted acid sites consisted of two kinds of OH bands at high and low wavenumbers, ascribable to OH bands situated on 12- and 8-member rings (MR) of mordenite structure, respectively. The amount and strength of these Brønsted hydroxyls were measured quantitatively based on a theoretical equation using a curve fitting method. Up to ca. 30% of the exchange degree, NH4(+) was exchanged with Na+ on the 12-MR to arrive at saturation; therefore, in this region, the Brønsted acid site was situated on the large pore of 12-MR. The NH4(+) cation was then exchanged with Na+ on 8-MR, and finally exceeded the amount on 12-MR. In the 99% NH4-mordenite, Brønsted acid sites were located predominantly on the 8-MR more than on the 12-MR. Irrespective of the NH4(+) exchange degree, the strengths deltaH of Brønsted OH were 145 and 153 kJ mol(-1) on the 12- and 8-MR, respectively; that is, the strength of Brønsted acid site on the 8-MR was larger than that on the 12-MR. A density functional theory (DFT) calculation supported the difference in the strengths of the acid sites. Catalytic cracking activity of the Brønsted acid sites on the 8-MR declined rapidly, while that on the 12-MR was remarkably kept. The difference in strength and/or steric capacity may cause such a difference in the life of a catalyst. PMID:16853412

Niwa, Miki; Suzuki, Katsuki; Katada, Naonobu; Kanougi, Tomonori; Atoguchi, Takashi

2005-10-13

26

Characteristics of copper ion exchanged mordenite catalyst deactivated by HCl for the reduction of NO x with NH 3  

Microsoft Academic Search

The deactivation characteristics of copper ion exchanged mordenite type zeolite catalyst (CuHM) by HCl for the reduction of NOx, particularly from an incinerator with NH3, have been investigated over a fixed bed flow reactor system. X-ray absorption near edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), synchrotron radiation X-ray diffraction (SR-XRD), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption

Jin Woo Choung; In-Sik Nam

2006-01-01

27

Equilibria and heats of exchange of alkaline-earth metal ions on the Na form of mordenite  

Microsoft Academic Search

Sorption-analytic studies of ion exchange equilibria combined with direct calorimetric measurements of the heats of ion exchange\\u000a sorption of the Ca2+, Sr2+, and Ba2+ cations were performed over the whole range of solid phase fillings with sorbed cations on the Na forms of two mordenites\\u000a prepared from natural specimens rich in Na+ and Ca2+ cations. Ion exchange constants were determined

Yu. I. Tarasevich; V. E. Polyakov; D. A. Krysenko

2010-01-01

28

Effect of Temperature on the Pb (II) Removal from Single Aqueous Solutions by a Locally Natural Mordenite: Equilibrium and Kinetic Modeling  

Microsoft Academic Search

Zeolites have been shown to be effective adsorbents for the removal of heavy metals from aqueous solutions. In this study, mordenite (a natural zeolite) has been used for the removal of lead ions to evaluate its potential use as a low?cost adsorbent. Batch experiments have been conducted to evaluate the equilibrium and process kinetics at different temperatures. The equilibrium experimental

Xue Song Wang; Lei He; Hai Qiong Hu; Jin Wang

2008-01-01

29

On the Elastic Behaviour of Zeolite Mordenite: a Synchrotron Powder Diffraction Study  

SciTech Connect

The high-pressure elastic behavior of a synthetic zeolite mordenite, Na{sub 6}Al{sub 6.02}Si{sub 42.02}O{sub 96}{center_dot}19H{sub 2}O [a=18.131(2), b=20.507(2), c=7.5221(5) Angstroms, space group Cmc2{sub 1}], has been investigated by means of in situ synchrotron X-ray powder diffraction up to 5.68 GPa. No phase transition has been observed within the pressure range investigated. Axial and volume bulk moduli have been calculated using a truncated second-order Birch-Murnaghan equation-of-state (II-BM-EoS). The refined elastic parameters are: V{sub 0}=2801(11) Angstroms{sup 3}, K{sub T0}= 41(2) GPa for the unit-cell volume; a 0=18.138(32) Angstroms, K {sub T0}(a)=70(8) GPa for the a-axis; b 0=20.517(35) Angstroms, K{sub T0}(b)=29(2) GPa for the b-axis and c 0=7.531(5) Angstroms, K {sub T0}(c)=38(1) GPa for the c-axis [K {sub T0}(a): K {sub T0}(b): K {sub T0} (c)=2.41:1.00:1.31]. Axial and volume Eulerian finite strain versus 'normalized stress' plots (fe-Fe plot) show an almost linear trend and the weighted linear regression through the data points yields the following intercept values: Fe(0)=39(4) GPa for V; Fe {sub a} (0)=65(18) GPa for a; Fe {sub b} (0)=28(3) GPa for b; Fe {sub c} (0)=38(2) GPa for c. The magnitudes of the principal Lagrangian unit-strain coefficients, between 0.47 GPa (the lowest HP-data point) and each measured P>0.47 GPa, were calculated. The unit-strain ellipsoid is oriented with {var_epsilon}{sub 1} || b, {var_epsilon}{sub 2} || c, {var_epsilon}{sub 3} || a and |{var_epsilon}{sub 1}|> |{var_epsilon}{sub 2}|> |{var_epsilon}{sub 3}|. Between 0.47 and 5.68 GPa the relationship between the unit-strain coefficient is {var_epsilon}{sub 1}: {var_epsilon}{sub 2}: {var_epsilon}{sub 3}=2.16:1.81:1.00. The reasons of the elastic anisotropy are discussed.

Gatta,G.; Lee, Y.

2006-01-01

30

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

PubMed

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

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

2005-01-20

31

A study of silver species on silver-exchanged ETS-10 and mordenite by XRD, SEM and solid-state 109Ag, 29Si and 27AI NMR spectroscopy.  

PubMed

Silver zeolites, especially Ag-ETS-10 and Ag-mordenite, actively bind xenon and iodine, two prime contaminants common to nuclear accidents. The evolution of silver species on silver exchanged ETS-10 (Ag/ETS-10) and mordenite (Ag/Mor) has been investigated by exposing the materials to a series of activation conditions in Ar, air and H2. The samples were characterized by XRD, SEM and solid-state 109Ag, 29Si and 27AI MAS NMR. The silver reduction and structural evolution have been illustrated by those techniques. The effectiveness of one sample of each type of sieve was tested for its ability to trap mercury from a gas stream. However, the results from this study demonstrate that the adsorption characteristics of silver-loaded sieves cannot necessarily be predicted using a full complement of structural characterization techniques, which highlights the importance of understanding the formation and nature of silver species on molecular sieves. PMID:22962758

Liu, Yan; Chen, Fu; Wasylishen, Roderick E; Xu, Zhenghe; Sawada, James; Kuznicki, Steven M

2012-08-01

32

Adsorption of H 2 O, NH 3 and C 6 H 6 on alkali metal cations in internal surface of mordenite and in external surface of smectite: a DFT study  

Microsoft Academic Search

Adsorption of H2O, NH3 and C6H6 on H- and alkali metal-exchanged structures of mordenite and on corresponding cations on the smectite layer is investigated\\u000a by ab initio density-functional calculations. Proton or an alkali metal cation compensates one Al\\/Si framework substitution\\u000a and resides in the extra-framework position of zeolite or above flat smectite layer close to the Al\\/Si substitution. Pronounced\\u000a similarities

Lubomir Benco; Daniel Tunega

2009-01-01

33

Effects of Zeolite Structure And Composition on the Synthesis of Dimethyl Carbonate By Oxidative Carbonylation of Methanol on Cu-Exchanged Y, ZSM-5, And Mordenite  

SciTech Connect

The aim of this work was to establish the effects of zeolite structure/chemical composition on the activity and selectivity of Cu-exchanged Y (Si/Al = 2.5), ZSM-5 (Si/Al = 12), and Mordenite (Si/Al = 10) for the oxidative carbonylation of methanol to DMC. Catalysts were prepared by solid-state ion-exchange of the H-form of each zeolite with CuCl and were then characterized by FTIR and X-ray absorption spectroscopy (XAS). The XANES portion of the XAS data showed that all of the copper was present as Cu{sup +} cations, and analysis of the EXAFS portion of the data shows the Cu{sup +} cations had a CuO coordination number of 2.1 on Cu-Y and 2.7 on Cu-ZSM-5 and Cu-MOR. Dimethyl carbonate (DMC) was observed as the primary product when a mixture of CH{sub 3}OH/CO/O{sub 2} was passed over Cu-Y, whereas dimethoxy methane was the primary product over Cu-ZSM-5 and Cu-MOR. The higher activity and selectivity of Cu-Y for the oxidative carbonylation of methanol can be attributed to the weaker adsorption of CO on the Cu{sup +} cations exchanged into Y zeolite. In situ IR observations revealed that under reaction conditions, adsorbed CO was displaced by methoxide groups bound to the Cu{sup +} cations. The kinetics of DMC synthesis suggests that the rate-limiting step in the formation of this product was the insertion of CO into CuOCH{sub 3} bonds. The yield of DMC decreased with methanol conversion, likely due to the hydrolysis of DMC to methanol and carbon dioxide.

Zhang, Y.; Briggs, D.N.; Smit, E.de; Bell, A.T.

2009-06-04

34

Adsorption of H2O, NH3 and C6H6 on alkali metal cations in internal surface of mordenite and in external surface of smectite: a DFT study  

NASA Astrophysics Data System (ADS)

Adsorption of H2O, NH3 and C6H6 on H- and alkali metal-exchanged structures of mordenite and on corresponding cations on the smectite layer is investigated by ab initio density-functional calculations. Proton or an alkali metal cation compensates one Al/Si framework substitution and resides in the extra-framework position of zeolite or above flat smectite layer close to the Al/Si substitution. Pronounced similarities between zeolite and smectite are observed in changes of the adsorption energies and location of the external cation with changing character of the external cation. Calculated adsorption energies exhibit the following trend: E(NH3) > E(H2O) > E(C6H6). Because of looser contact with the framework, zeolitic cations are stronger adsorption centers and calculated adsorption energies of zeolites are by ~20-30% larger than cations of smectites. The highest adsorption energy is calculated for H-exchanged structures and down the group of alkali metal cations a decrease of the adsorption energy is observed. Deviations from the smooth variation of the adsorption energy are caused by: (1) formation of strong hydrogen bonds in H-exchanged structures, (2) adsorption induced migration of the external Li+ cation, and (3) steric hindrances of the flat C6H6 molecule adsorbed on the cation in the cage of zeolite.

Benco, Lubomir; Tunega, Daniel

2009-05-01

35

The growth of zeolites A, X and mordenite in space  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

36

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

Microsoft Academic Search

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

Shaneela Nosheen

2009-01-01

37

Interaction between organic vapors and clinoptilolite-mordenite rich tuffs in parent, decationized, and lead exchanged forms.  

PubMed

Scientific interest in adsorption phenomena of organic vapors has concentrated on synthetic zeolites. Solid-vapor systems containing natural zeolites deserve special attention due to their abundance and environmental applications. Adsorption thermodynamic characteristics for benzene, toluene, n-hexane, and CCl(4) were measured on clinoptilolite-rich zeolitic tuffs from Mexico (ZE) and Hungary (ZH) on parent, decationized, dealuminated, and lead-exchanged samples. The clinoptilolite structure released Na(+) and Ca(2+) by acid treatment and this was accompanied by dealumination to a greater extent on ZE than on ZH. The exchange isotherm of Pb(2+) on ZE exhibited a concave type "a" form and accomplished 95% exchange and the tuff was selective at X(i(s))<0.25. The pattern of adsorption isotherms was the same on all tuffs: benzene>toluene>n-hexane>carbon tetrachloride. The -DeltaH values were higher for toluene than for the other adsorbates. Curves of q(isost) vs coverage decreased with the increment of the adsorbed amount in practically all studied systems. The contributions to the solid-vapor interaction potential were examined using inverse gas chromatography. The specific interaction energy G(sp) was primarily due to adsorbate-framework and adsorbate-cation interactions at low adsorbate pressures producing low surface coverage. PMID:17467725

Elizalde-González, M P; Pérez-Cruz, M A

2007-08-15

38

Studies of C 8 aromatics adsorption in BaY and mordenite molecular sieves using the headspace technique  

Microsoft Academic Search

A headspace technique, that consists in analyzing the composition of the vapor phase in equilibrium with the condensed phase\\u000a of a mixture in a sealed vial containing the adsorbent sample, has been recently applied to acquire equilibrium data for adsorption\\u000a of xylenes in liquid phase. In this study, we used this technique to measure experimental binary equilibrium data for C8

F. Murilo T. Luna; Juliana A. Coelho; J. Carlos F. Otoni; Artemis P. Guimarães; Diana C. S. Azevedo; Célio L. Cavalcante

2010-01-01

39

Differential thermal analysis as an acidity probe in zeolite catalysts  

SciTech Connect

Differential thermal analysis is used as an acidity strength probe for a series of mordenite (zeolite) catalysts via determining the temperature at which presorbed pyridine completely desorbs from the catalyst. The findings obtained for metal(s) containing mordenite catalysts have been correlated with the Pearson's assumption concerning Lewis acids and bases and the Pauling's electronegativity of the metals contained and found compatible.

Aboul-Gheit, A.K.; Al-Hajjaji, M.A.; Menoufy, M.F.; Abdel-Hamid, S.M.

1986-01-01

40

Quantitative Analysis of Water Confined in Ion-Exchanged Zeolites  

NASA Astrophysics Data System (ADS)

Zeolites, which host large quantities of water, are among the most important rock-forming and environmental minerals in the surface and near-surface regions of the Earth. The physical properties and geochemical behavior of water confined in zeolites differs substantially from that of bulk liquid water, and the energectics of confined water exerts a profound influence on the stability and behavior of zeolites in natural and engineered systems. Because the cations and water molecules are both located in the zeolitic channels, changes in cation content can influence the amount and site occupancies of water molecules in zeolites. In order to find out the relationship between the behavior of confined water and cation composition in zeolites, thermogravimetric and calorimetric experiments were conducted on the mordenite (one of the most common zeolites) samples of mixing Na+ and K+. These mordenite solid solutions were generated by binary ion exchange between pure synthetic Na-mordenite (CBV 10A, obtained from Zeolyst International) and chloride solutions containing Na+ and K+ of different equivalent concentration ratios. The results from dehydration and hydration of the mordenite solid solutions show that when the mole fraction of K+ in mordenite increases, the maximum water content of mordenite decreases and the enthalpy of hydration becomes less exothermic. More importantly, both maximum water content and enthalpy of hydration of mordenite are demonstrated to change linearly with mole fraction of K+. Two energetically distinct sets of water molecules have been observed in mordenite: W1 (relatively less energetic) and W2 (relatively high energetic). Thermodynamic analysis on the hydration of W1 and W2 reveals that these two sets of water molecules behave differently when cation composition of mordenite changes. The water content of W2 is independent of cation composition, whereas W1 loses water with when mole fraction of K+ increases; the enthalpy of hydration of W1 appears to be constant, but that of W2 becomes less exothermic with increasing mole fraction of K+.

Wang, J.; Neuhoff, P. S.

2009-12-01

41

Effect of natural zeolite on methane production for anaerobic digestion of ammonium rich organic sludge.  

PubMed

The effect of an inorganic additive on the methane production from NH(4+)-rich organic sludge during anaerobic digestion was investigated using different kinds of inorganic adsorbent zeolites (mordenite, clinoptilolite, zeolite 3A, zeolite 4A), clay mineral (vermiculite), and manganese oxides (hollandite, birnessite). The additions of inorganic materials resulted in significant NH4+ removals from the natural organic sludge ([NH4+]=1, 150 mg N/l), except for the H-type zeolite 3A and birnessite. However, an enhanced methane production was only achieved using natural mordenite. Natural mordenite also enhanced the methane production from the sludge with a markedly high NH4+ concentration (4500 mg N/l) during anaerobic digestion. Chemical analyses of the sludge after the digestion showed considerable increases in the Ca2+ and Mg2+ concentrations in the presence of natural mordenite, but not with synthetic zeolite 3A. The effect of Ca2+ or Mg2+ addition on the methane production was studied using Na(+)-exchanges mordenite and Ca2+ or Mg(2+)-enriched sludge. The simultaneous addition of Ca2+ ions and Na(+)-exchanged mordenite enhanced the methane production; the amount of produced methane was about three times greater than that using only the Na(+)-exchanged mordenite. In addition, comparing the methane production by the addition of natural mordenite or Ca2+ ions, the methane production with natural mordenite was about 1.7 times higher than that with only Ca2+ ions. The addition of 5% and 10% natural mordenite were suitable condition for obtaining a high methane production. These results indicated that the Ca2+ ions, which are released from natural mordenite by a Ca2+/NH4+ exchange, enhanced the methane production of the organic waste at a high NH4+ concentration. Natural mordenite has a synergistic effect on the Ca2+ supply as well on the NH4+ removal during anaerobic digestion, which is effective for the mitigation of NH4+ inhibition against methane production. PMID:15491827

Tada, Chika; Yang, Yingnan; Hanaoka, Toshiaki; Sonoda, Akinari; Ooi, Kenta; Sawayama, Shigeki

2005-03-01

42

Rate parameters from low-pressure steady-state protolytic cracking and dehydrogenation of isobutane over zeolite catalysts  

Microsoft Academic Search

An improved low-pressure steady-state technique has been used to accurately determine kinetic parameters for isobutane protolytic cracking and dehydrogenation over HZSM-5 (SiO2\\/Al2O3=33.0), HZSM-5 (94.2), ferrierite (55.2) and mordenite (20.0). Apparent activation energies for cracking are 104±5kJmol?1 over HZSM-5 (33.0) and 101±10kJmol?1 over mordenite. For isobutane dehydrogenation, energy barriers are 136±6kJmol?1 over HZSM-5 (33.0), HZSM-5 (94.2) and ferrierite, while over mordenite

Cam Le Minh; Trevor C. Brown

2006-01-01

43

Separation of Cesium and Strontium with Zeolites.  

National Technical Information Service (NTIS)

Basic studies of separation of cesium and strontium were made with specimens of zeolite, including the synthetic zeolites A, X and Y, synthetic mordenite, natural modernite and clinoptilolite. Ammonium chloride, which is considered to be the most suitable...

T. Kanno H. Hashimoto

1976-01-01

44

Mining Environmental Target Investigation: Natural Zeolites.  

National Technical Information Service (NTIS)

Information on the mining and processing of zeolites is reviewed. Composition, structure, and varieties of zeolite, including erionite (12510428), mordenite (12043742), natrolite (1318952), ferrierite (12173307), and phillipsite (12174184) are presented. ...

A. Albers

1981-01-01

45

Catalytic properties of natural zeolites. I. Conversions of aromatic hydrocarbons  

SciTech Connect

The catalytic properties of activated natural zeolites from Cuba, viz., mordenite and clinoptilolite, in the hydrogenation of benzene, the disproportionation of toluene, the isomerization of xylenes, and the cracking of ethylbenzene have been investigated.

Gonzales, H.A.; Romanovskii, B.V.; Topchieva, K.V.

1983-06-01

46

New catalysts for the indirect liquefaction of coal. Third quarterly technical report, February 1-April 30, 1982  

SciTech Connect

The evaluation of some iron/mordenite catalysts for synthesis gas conversion has been conducted. Mordenites with SiO/sub 2/:Al/sub 2/O/sub 3/ ratios of 11.4, 17.4 and 61.8:1 have been used. The effect of SiO/sub 2/:Al/sub 2/O/sub 3/ ratio on the product distribution has been determined.

Melson, G. A.

1982-01-01

47

Adsorption of argon, oxygen, and nitrogen on silver exchanged ETS10 molecular sieve  

Microsoft Academic Search

The adsorption of argon, oxygen, and nitrogen were studied on silver exchanged titanosilicate molecular sieve ETS-10 and the silver exchanged aluminosilicate molecular sieve mordenite by inverse gas chromatography and volumetric adsorption isotherm measurements. Silver exchanged zeolites, especially silver-mordenite, have been noted to demonstrate some degree of selectivity for argon\\/oxygen. Ag-ETS-10 is found to have a selectivity of 1.49 for argon

Alejandro Ansón; Steven M. Kuznicki; Tetyana Kuznicki; Tony Haastrup; Yingnan Wang; Christopher C. H. Lin; James A. Sawada; Edward M. Eyring; Douglas Hunter

2008-01-01

48

Method for treating a nuclear process off-gas stream  

DOEpatents

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

Pence, Dallas T. (San Diego, CA); Chou, Chun-Chao (San Diego, CA)

1984-01-01

49

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

SciTech Connect

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

Shakhtakhtinskii, T.N.; Aliev, A.M.; Kuliev, A.R. [Institute of Theoretical Problems of Chemical Technology, Baku (Azerbaijan)

1995-08-01

50

Use of Hammett indicators for acidity measurements in zeolites  

Microsoft Academic Search

Titration of sodium Y faujasite (Na-Y), hydrogen Y faujasite (H-Y), sodium mordenite (Na-M), and hydrogen mordenite (H-M) with n-butylamine in the presence of Hammett indicators showed strong acidity for H-Y (2.0 meq\\/g of pK\\/sub a\\/-8.2, 2.8 meq\\/g of pK\\/sub a\\/+6.8) and nearly zero acidity for Na-Y and NaH. The acidity of H-M could not be determined because the indicators could

W. F. Kladnig

1979-01-01

51

Molecule sieving catalysts for NO reduction with hydrocarbons in exhaust of lean burn gasoline and diesel engines  

Microsoft Academic Search

NO oxidation catalysts with small pores and low hydrocarbon oxidation activity owing to molecular sieving were prepared by dispersing platinum in the pores of ferrierite and chabazite zeolites. These small pore platinum zeolite crystals were physically mixed with large pore silver mordenite zeolite crystals and evaluated as HC-SCR catalysts for selective catalytic reduction of NO in a synthetic gas mixture

J. A Martens; A Cauvel; F Jayat; S Vergne; E Jobson

2001-01-01

52

Characterization and environmental application of a Chilean natural zeolite  

Microsoft Academic Search

The use of natural zeolites for environmental applications is gaining new research interests mainly due to their properties and significant worldwide occurrence. The present work describes the characterization of a natural Chilean zeolite and the results as adsorbent for ammonia from aqueous solutions. The zeolitic-rich tuff sample, mainly composed of clinoptilolite and mordenite, consisted of 13 ?m mean volumetric particle

A. H. Englert; J. Rubio

2005-01-01

53

Reactions of aliphatic ketones on zeolites  

Microsoft Academic Search

Reactions of some ketones (acetone, methyl ethyl ketone and diethyl ketone) on the H-form of ZSM-5, ZSM-11, mordenite and erionite have been studied in an integral reactor. At a reaction temperature of 300 or 350°C acetone is selectively transformed on all these zeolites into isobutene, while with higher ketones substantial amounts of aromatics are formed.

K. Nedomová; S. Beran

1986-01-01

54

Ion Exchange Behavior of Natural Zeolites in Distilled Water, Hydrochloric Acid, and Ammonium Chloride Solution  

Microsoft Academic Search

This study presents basic research on the use of natural zeolites for the removal of ammonium ions from aqueous solutions. Three natural zeolites from Shimane, Japan, used in this study are shown to contain varying amounts of clinoptilolite and mordenite. The chemical behavior of these natural zeolites was investigated in distilled water, hydrochloric acid, and ammonium chloride solution. The amount

Yujiro Watanabe; Hirohisa Yamada; Hisao Kokusen; Junzo Tanaka; Yusuke Moriyoshi; Yu Komatsu

2003-01-01

55

Zeolitized pyroclastic rocks from Oaxaca (southern Mexico): Mineralogy, ion-exchange properties, and use  

Microsoft Academic Search

Two quarries for construction material, situated in the southernmost parts of the Mexican Mid- ?ertiary pyroclastic complex (in Sierra Madre del Sur), 7-8 km SE of Oaxaca City are sampled. They have rhyolitic composition and consist of glass shards, pumice and few plagioclase, quartz, biotite, magnetite phenocrysts and lithic clasts (probably andesites). Clinoptilolite, mordenite and light-green clay minerals replace all

Yotzo Yanev; Nikolai Popov; Tzvetoslav Iliev; Todorka Popova

2007-01-01

56

Removal of Heavy Metals and Other Cations from Wastewater Using Zeolites  

Microsoft Academic Search

Zeolites from abundant natural deposits were investigated by the Bureau of Mines for efficiently cleaning up mining industry wastewaters. Twenty-two zeolites were analyzed by X-ray diffraction and inductively coupled plasma analysis (ICP). These included clinoptilolite, mordenite, chabazite, erionite, and phillipsite. The zeolites were primarily in the sodium or calcium form, but potassium and magnesium counter ions were also present. Bulk

M. J. Zamzow; B. R. Eichbaum; K. R. Sandgren; D. E. Shanks

1990-01-01

57

Determination of the acid strength of solid catalysts in water by means of a kinetic tracer  

Microsoft Academic Search

The kinetic analysis of the hydrolysis of acetals in the presence of various solid acid catalysts, dealuminated H-form mordenites, H-montmorillonite and strong ion exchange resins has been carried out. Experiments performed in water as the solvent at different agitation speeds, catalyst weights and acetal concentrations show that the reaction is not controlled by external diffusion, nor by internal diffusion as

Claude Moreau; Robert Durand; Patrick Geneste; Samir Mseddi

1996-01-01

58

Removal of sulfamethoxazole sulfonamide antibiotic from water by high silica zeolites: a study of the involved host-guest interactions by a combined structural, spectroscopic, and computational approach.  

PubMed

Sulfonamide antibiotics are persistent pollutants present in surface and subsurface waters in both agricultural and urban environments. Sulfonamides are of particular concern in the environment because they are known to induce high levels of bacterial resistance. Adsorption of sulfamethoxazole sulfonamide antibiotic into three high silica zeolites (Y, mordenite, and ZSM-5) with pore opening sizes comparable to sulfamethoxazole dimensions is reported. Sulfamethoxazole was almost completely removed from water by zeolite Y and MOR in a few minutes. Adsorption onto ZSM-5 showed an increased kinetics with increasing temperature. Antibiotic sorption was largely irreversible with little antibiotic desorbed. Sulfamethoxazole incorporation and localization into the pore of each zeolite system was defined along with medium-weak and cooperative host-guest interactions in which water molecules play a certain role only in zeolite Y and mordenite. PMID:24491342

Blasioli, Sonia; Martucci, Annalisa; Paul, Geo; Gigli, Lara; Cossi, Maurizio; Johnston, Cliff T; Marchese, Leonardo; Braschi, Ilaria

2014-04-01

59

Oxygen and hydrogen isotope geochemistry of zeolites  

NASA Technical Reports Server (NTRS)

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

Karlsson, Haraldur R.; Clayton, Robert N.

1990-01-01

60

The adsorption of fatty acids from vegetable oils with zeolites and bleaching clay\\/zeolite blends  

Microsoft Academic Search

The adsorption of model fatty acids (hepatnoic, oleic), using spiked vegetable oils, was studied using different kinds of\\u000a zeolites (A-zeolite, X, Y-zeolites, mordenite), Y-zeolite exchanged with different cations (alkali, alkaline earth, transition\\u000a metal ions), and with bleaching clay\\/zeolite blends. The adsorption process was shown to be governed by the molecular sieving\\u000a properties of the zeolites involved as well as the

D. R. Taylor; C. B. Ungermann; Z. Demidowicz

1984-01-01

61

Nonempirical molecular orbital study of the siting and pairing of aluminum in ferrierite  

SciTech Connect

Ab initio molecular orbital calculations were performed on model clusters with a geometry derived from the known structure of ferrierite. The data show that siting and pairing of aluminum probably take place preferentially in the six-membered rings. As observed earlier for mordenite and zeolite ZSM-5, charge distribution analyses indicate the highly covalent nature of the zeolitic framework and its behavior as a weak but soft (anionic) base. 26 references, 10 figures, 8 tables.

Fripiat, J.G.; Galet, P.; Delhalle, J.; Andre, J.M.; Nagy, J.B.; Derouane, E.G.

1985-05-09

62

Oxygen and hydrogen isotope geochemistry of zeolites  

NASA Astrophysics Data System (ADS)

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

Karlsson, Haraldur R.; Clayton, Robert N.

1990-05-01

63

Effect of natural zeolite on methane production for anaerobic digestion of ammonium rich organic sludge  

Microsoft Academic Search

The effect of an inorganic additive on the methane production from NH4+-rich organic sludge during anaerobic digestion was investigated using different kinds of inorganic adsorbent zeolites (mordenite, clinoptilolite, zeolite 3A, zeolite 4A), clay mineral (vermiculite), and manganese oxides (hollandite, birnessite). The additions of inorganic materials resulted in significant NH4+ removals from the natural organic sludge ([NH4+]=1, 150 mgN\\/l), except for

Chika Tada; Yingnan Yang; Toshiaki Hanaoka; Akinari Sonoda; Kenta Ooi; Shigeki Sawayama

2005-01-01

64

Effect of zeolites on chitosan\\/zeolite hybrid membranes for direct methanol fuel cell  

Microsoft Academic Search

Zeolites including 3A, 4A, 5A, 13X, mordenite, and HZSM-5 were incorporated into chitosan (CS) matrix to fabricate the hybrid membranes for direct methanol fuel cell (DMFC). Due to the presence of hydrogen bonds between CS and zeolite, the hybrid membranes displayed desirable thermal and mechanical stabilities. Through free volume characteristics analysis by positron annihilation lifetime spectroscopy (PALS) technique, it was

Jingtao Wang; Xiaohong Zheng; Hong Wu; Bin Zheng; Zhongyi Jiang; Xiaopeng Hao; Baoyi Wang

2008-01-01

65

Selective catalytic reduction of NO with methane on gallium catalysts  

Microsoft Academic Search

Gallium species supported on H-ZSM-5 and on H-mordenite are active catalysts for NO reduction with methane in the presence of excess O[sub 2]. Over Ga-H-ZSM-5, the NO reduction rate is first order in NO with a variable, fractional order in CH[sub 4]. The distinct feature of these gallium-based catalysts is their very high CH[sub 4] selectivities for NO[sub x] reduction.

Yuejin Li; J. N. Armor

1994-01-01

66

Adsorption of methane, ethane and ethylene on molecular sieve zeolites  

Microsoft Academic Search

Adsorption of pure methane, ethane and ethylene on molecular sieve zeolites was examined via the gas chromatographic method to determine the potential for the separation of ethylene from light hydrocarbons. The molecular sieves chosen for the study were H-mordenite and 13X, CaX, 4A and 5A zeolites. Henry's law constants were determined over a variety of temperature ranges between 233 and

R. W. Triebe; F. H. Tezel; K. C. Khulbe

1996-01-01

67

Removal of Metal Cations from Water Using Zeolites  

Microsoft Academic Search

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 (-40, +65 mesh) varied from 0.48 to 0.93 g\\/mL. Attrition losses ranged from 1 to

M. J. Zamzow; J. E. Murphy

1992-01-01

68

Carcinogenic and fibrogenic effects of zeolites: preliminary observations  

SciTech Connect

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 ..mu..m in length (1 ..mu..m average, 95% shorter than 8 ..mu..m) and 0.01-2.5 ..mu..m in width (0.1 ..mu..m average, 94.4% smaller than 1 ..mu..m). The granular mordenite was 0.33-5.7 ..mu..m in the long axis and 0.27-1.67 ..mu..m in the short axis. The fibrous mordenite was 0.4-6 ..mu..m in length and 0.05-0.67 ..mu..m in width. Thirteen untreated mice and five mice treated with 10 mg chrysotile (Calidria, 90% shorter than 1 ..mu..m) 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.

Suzuki, Y.

1982-04-01

69

Dehydration of cyclohexanol as a test reaction for zeolite acidity  

SciTech Connect

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

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

1984-01-01

70

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

Microsoft Academic Search

\\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

C. Colella; Piazza Ie; V. Tecchio

71

Thermal stability of zeolitic tuff from Yucca Mountain, Nevada  

SciTech Connect

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

Bish, D.L.

1990-04-01

72

Transformation of thiophenic compounds over acidic zeolites  

Microsoft Academic Search

The transformation of thiophenic compounds (2-methylthiophene; 3-methylthiophene; 2,3-dimethylthiophene; 2,5-dimethylthiophene; 2-methylbenzothiophene; 3-methylbenzothiophene) was carried out over HY zeolite at 350°C under atmospheric pressure in a fixed bed reactor. The transformation of some of them was also carried out over H?, HZSM5 and H-mordenite (HMOR). In the presence of HY, all the reactants underwent both isomerization and disproportionation in various proportions depending

T. Boita; M. Moreau; F. Richard; G. Pérot

2006-01-01

73

Mechanism of neopentane cracking over solid acids  

Microsoft Academic Search

Neopentane was used as a probe to test whether catalyst protons can attack the C-C and\\/or the C-H sigma-bonds in the cracking of alkanes. Over a variety of solid acids approximately one CHâ molecule was formed for every neopentane reacted. Moreover, in most cases nearly as much isobutene was formed. With H-Y zeolite (H-Y) and particularly with H-mordenite (H-M), however,

E. A. Lombardo; R. Pierantozzi; W. K. Hall

1988-01-01

74

Comparative study of the deactivation of Cr-BEA, Cr-MOR and Cr-ZSM-5 in catalytic decomposition of VOC  

Microsoft Academic Search

The catalytic activity and stability studies of chromium exchanged beta, mordenite and ZSM-5 zeolites for VOCs decomposition\\u000a are reported. Difference in deactivation behavior by the zeolites was observed. Cr-ZSM-5 (Si\\/Al=240) was the most stable catalyst\\u000a due to its high Si\\/Al ratio. It also has less coking tendency due to its uniform sized intersecting channel system.

A. A. Zuhairi; M. A. B. Zailani; S. Bhatia

2003-01-01

75

Fysicochemische EN Katalytische Evaluatie Van Door Zuurbehandeling Gedealumineerde H-Mordenieten  

NASA Astrophysics Data System (ADS)

The major goal of my PhD-research is to provide a fundamental insight into the parameters which determine the activity and product selectivity of acid leached H -mordenites during the catalytic cracking of n-alkanes. The physicochemical properties of these catalysts were characterized by classic chemical analysis techniques, high resolution magic angle spinning NMR, infrared spectroscopy and thermal analysis. To evaluate the catalytic cracking properties, n-hexane was used as a probe molecule to study the initial activity and deactivation behaviour of the dealuminated H-mordenites. These parameters were analyzed using gaschromatographic measurements. The results show that the accessibility of the acid groups inside the intracrystalline micropore volume is an important factor which controls the catalytic behaviour of acid leached mordenites. The extraction of framework aluminium results in a specific reorganization of the void structure and creates an open framework in which the reactant molecules can easily access the active sites. This process produces high active catalysts with an increased isomerisation -capacity and a prolonged lifetime.

Goovaerts, Filip Emiel

76

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

PubMed

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

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

2014-06-11

77

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

SciTech Connect

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

Komarneni, S.; Roy, R.

1982-03-01

78

Zeolite crystal growth in space - What has been learned  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

79

Reactions of hydroxymatairesinol over supported palladium catalysts  

Microsoft Academic Search

In this work, hydroxymatairesinol (extracted from Norway spruce knots) was hydrogenolyzed to matairesinol over palladium impregnated H-Beta-300, H-Beta-150, H-Beta-25, H-Beta-11, H-Y, H-Mordenite, H-MCM-41, H-ZSM-5, SiO2, and Al2O3. H-Beta-25 without palladium was also investigated. The hydrogenolysis was performed in 2-propanol at 70?°C under hydrogen and nitrogen atmospheres in a stirred glass reactor. The catalysts were characterized by nitrogen physisorption, direct current

Heidi Markus; Päivi Mäki-Arvela; Narendra Kumar; Teemu Heikkilä; Vesa-Pekka Lehto; Rainer Sjöholm; Bjarne Holmbom; Tapio Salmi; Dmitry Yu. Murzin

2006-01-01

80

Test Plan to Demonstrate Removal of Iodine and Tritium from Simulated Nuclear Fuel Recycle Plant Off-gas Streams using Adsorption Processes  

SciTech Connect

This letter documents the completion of the FCR&D Level 4 milestone for the Sigma Team – Off-Gas - ORNL work package (FT-14OR031202), “Co-absorption studies - Design system complete/test plan complete” (M4FT-14OR0312022), due November 15, 2013. The objective of this test plan is to describe research that will determine the effectiveness of silver mordenite and molecular sieve beds to remove iodine and water (tritium) from off-gas streams arising from used nuclear fuel recycling processes, and to demonstrate that the iodine and water can be recovered separately from one another.

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

2013-12-11

81

A comparative study for gas-phase dehydration of glycerol over H-zeolites  

Microsoft Academic Search

The gas-phase dehydration of glycerol was conducted over various H-zeolites, viz. H-ferrierite, H-?, H-ZSM-5, H-Y and H-mordenite with various SiO2\\/Al2O3 ratios. For comparison, ?-Al2O3 and silica-alumina were also examined. Several characterization techniques: X-ray diffraction (XRD), the temperature-programmed desorption of ammonia (NH3-TPD), the temperature-programmed desorption of water (H2O-TPD), temperature-programmed oxidation (TPO) with mass spectroscopy and CHNS analysis were employed to characterize

Yong Tae Kim; Kwang-Deog Jung; Eun Duck Park

2011-01-01

82

Pulsed laser deposition of zeolitic membranes  

SciTech Connect

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

Peachey, N.M.; Dye, R.C. [Los Alamos National Lab., NM (United States); Ries, P.D. [Dow Chemical Co., Midland, MI (United States)

1995-02-01

83

The interaction effects of dehydration function on catalytic performance and properties of hybrid catalysts upon LPDME process  

Microsoft Academic Search

Three bi-functional catalysts have been prepared by physical mixing of a commercial methanol synthesis catalyst (CuO–ZnO–Al2O3) with three different methanol dehydration catalysts including: H-MFI90, ?-Al2O3 and H-Mordenite in order to investigate the role of interaction effects of dehydration component on characteristic properties and performance of these admixed catalysts. The bi-functional catalysts have been characterized by XRD, N2 adsorption, H2-TPR, NH3-TPD

G. R. Moradi; M. Nazari; F. Yaripour

2008-01-01

84

Dehydration of aldoximes on rare earth exchanged (La 3+ , Ce 3+ , RE 3+ , Sm 3+ ) Na–Y zeolites: A facile route for the synthesis of nitriles  

Microsoft Academic Search

Rare earth exchanged Na–Y zeolites, H-mordenite, K-10 montmorillonite clay and amorphous silica-alumina were effectively employed\\u000a for the continuous synthesis of nitriles. Dehydration of benzaldoxime and 4-methoxybenzaldoxime were carried out on these\\u000a catalysts at 473 K. Benzonitrile (dehydration product) was obtained in near quantitative yield with benzaldoxime whereas;\\u000a 4-methoxybenzaldoxime produces both Beckmann rearrangement (4-methoxyphenylformamide) as well as dehydration products (4-methoxy\\u000a benzonitrile) in

Bejoy Thomas; S. Sugunan

2007-01-01

85

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

SciTech Connect

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

Fripiat, J.J.

1992-12-31

86

Aluminum coordination and active sites on aluminas, Y zeolites and pillared silicates  

SciTech Connect

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

Fripiat, J.J.

1992-01-01

87

Calibration analysis of zeolites by laser induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

2012-08-01

88

Removal of metal cations from water using zeolites  

SciTech Connect

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.

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

1992-11-01

89

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

90

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

NASA Astrophysics Data System (ADS)

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

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

1989-05-01

91

The zeolite deposits of Greece  

USGS Publications Warehouse

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

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

1996-01-01

92

Hydrolysis of cellulose by amorphous carbon bearing SO3H, COOH, and OH groups.  

PubMed

The hydrolysis of cellulose into saccharides using a range of solid catalysts is investigated for potential application in the environmentally benign saccharification of cellulose. Crystalline pure cellulose is not hydrolyzed by conventional strong solid Brønsted acid catalysts such as niobic acid, H-mordenite, Nafion and Amberlyst-15, whereas amorphous carbon bearing SO 3H, COOH, and OH function as an efficient catalyst for the reaction. The apparent activation energy for the hydrolysis of cellulose into glucose using the carbon catalyst is estimated to be 110 kJ mol (-1), smaller than that for sulfuric acid under optimal conditions (170 kJ mol (-1)). The carbon catalyst can be readily separated from the saccharide solution after reaction for reuse in the reaction without loss of activity. The catalytic performance of the carbon catalyst is attributed to the ability of the material to adsorb beta-1,4 glucan, which does not adsorb to other solid acids. PMID:18759399

Suganuma, Satoshi; Nakajima, Kiyotaka; Kitano, Masaaki; Yamaguchi, Daizo; Kato, Hideki; Hayashi, Shigenobu; Hara, Michikazu

2008-09-24

93

Influence of copper modifying additive on state of gold in zeolites  

NASA Astrophysics Data System (ADS)

The influence of copper modifying additive on state of gold in NaY and NH 4-mordenite has been investigated. The presence of copper in Au/Cu/NM permits to stabilize fine gold particles (˜8 nm), while for Au/Cu/NaY large particles with unusual complex structure and size up to 80 nm were registered. Furthermore, copper favors the formation of gold particles at low temperature. It was revealed the interaction of gold with copper to facilitate the activation of sites at low temperature due to change of redox and electronic properties of gold species. Gold clusters or gold species with strong chemical interaction with copper ions are active in CO oxidation at low temperature being sensitive to sample pretreatment. Gold nanoparticles are active at high temperature and are less sensitive to reaction conditions.

Smolentseva, E.; Bogdanchikova, N.; Simakov, A.; Pestryakov, A.; Tusovskaya, I.; Avalos, M.; Farías, M. H.; Díaz, J. A.; Gurin, V.

2006-09-01

94

Design and synthesis of metal sulfide catalysts supported on zeolite nanofiber bundles with unprecedented hydrodesulfurization activities.  

PubMed

Developing highly active hydrodesulfurization (HDS) catalysts is of great importance for producing ultraclean fuel. Herein we report on crystalline mordenite nanofibers (NB-MOR) with a bundle structure containing parallel mesopore channels. After the introduction of cobalt and molybdenum (CoMo) species into the mesopores and micropores of NB-MOR, the NB-MOR-supported CoMo catalyst (CoMo/NB-MOR) exhibited an unprecedented high activity (99.1%) as well as very good catalyst life in the HDS of 4,6-dimethyldibenzothiophene compared with a conventional ?-alumina-supported CoMo catalyst (61.5%). The spillover hydrogen formed in the micropores migrates onto nearby active CoMo sites in the mesopores, which could be responsible for the great enhancement of the HDS activity. PMID:23895581

Tang, Tiandi; Zhang, Lei; Fu, Wenqian; Ma, Yuli; Xu, Jin; Jiang, Jun; Fang, Guoyong; Xiao, Feng-Shou

2013-08-01

95

Correlations and characterization of porous solids by fractal dimension and porosity  

NASA Astrophysics Data System (ADS)

The fractal dimensions of zeolite A, zeolite X, Dowex MSC-1, Mordenite, zeolite Y, ZSM-5 and MSC-5A carbon sieve have been obtained by physical adsorption of different-sized adsorbates. The porosity of the solids is obtained from literature. Two simple equations with two integral variables can be employed to characterize a porous solid with finite fractal dimension and porosity. These two equations also illustrate the correlation between fractal dimension and porosity of the porous solid and are also helpful to construct the fractal structure of the porous solids. Two integral variables are the number of divisions (cuts) in each dimension, and the number of the d-dimensional objects ( d can be 1, 2 or 3) that must be taken for iteration. Seven examples of porous solids are employed to characterize and illustrate the applicability of the two equations.

Huang, S. J.; Yu, Y. C.; Lee, T. Y.; Lu, T. S.

1999-12-01

96

Picosecond infrared pump-probe spectrum of D2O adsorbed at acid OD group of zeolite  

NASA Astrophysics Data System (ADS)

Spectroscopic and dynamic features of the vibrationally excited D2O/zeolite system have been investigated by two-color infrared-infrared pump-probe experiment. The frequency- and delay-scanned probe intensities were measured by tuning the pump laser to the OD stretching bands of the D2O molecule hydrogen bonded to the acidic OD group of mordenite zeolite. Two types of pump-induced signals were observed: the ones which have the population lifetime of 43+/-5 ps and display frequency shift by the pumping frequency, and the others, which have the lifetime of about 15 ps and exhibit no such frequency shift. Possible origins of the signals are discussed.

Fujino, T.; Kashitani, M.; Onda, K.; Wada, A.; Domen, K.; Hirose, C.; Ishida, M.; Goto, F.; Kano, S. S.

1998-08-01

97

Propylene oligomerization over zeolite catalysts  

SciTech Connect

Zeolites (ZSM-5, boralites, offretite, HY, mordenite, and omega) were bonded with 20 wt% sepiolite into composite catalysts to oligomerize propylene in a fixed-bed, automated pilot unit operating at 30-50 atm under isothermal conditions. Product distributions indicate that oligomer size and structure correlates well with the zeolite pore diameter. In addition to C/sub 6/-C/sub 12/ and higher oligomers, aromatics and branched saturates are formed, indicating the presence of cracking, hydrogen and methyl transfer, isomerization, and dehydrocyclization reactions. Offretite (and HY) minimize C/sub 7/ and C/sub 8/ formation, while the boralite used has shown better oligomerization activity and product yields than either ZSM-5 or the other zeolites tested.

Hsu, J.T.; Galya, L.G.; Occelli, M.L.

1984-08-01

98

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

SciTech Connect

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

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

1983-01-01

99

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

SciTech Connect

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

Yoshida, R. (Government Industrial Development Lab., Hokkaido, Japan); Hara, S.; Yoshida, T.; Yokoyama, S.; Nakata, Y.; Goto, Y.; Maekawa, Y.

1983-01-01

100

Base-modified zeolite-containing catalysts for the conversion of synthesis gas to alcohols  

SciTech Connect

This patent describes a zeolite-containing heavy metal oxide catalyst for preparing lower aliphatic alcohols which comprises reacting carbon monoxide and hydrogen under carbon monoxide-hydrogenation conditions, the catalyst comprising: a zeolite support consisting of a member selected from the group consisting of Y zeolite, X zeolite, aluminophosphate, ZSM-5, ZSM-11, silicalite, zeolite A and mordenite; at least one heavy metal oxide selected from the group consisting of molybdenum oxide, tungsten oxide and rhenium oxide; optionally a heavy metal oxide from the group of elements consisting of cobalt oxide, iron oxide and nickel oxide; and a promoter comprising an alkali or alkaline earth element in free or combined form. The improvement consists of improving the selectivity to the alcohols by treating the zeolite support with a nitrogen-containing base selected from the group consisting of urea, dimetholurea, cyanuric acid, melamine, melan, melem and melon.

Bhattacharya, A.K.; Bolmer, M.S.; Prada-Silva, G.

1989-04-18

101

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

SciTech Connect

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.

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

1991-01-01

102

Zeolite-clay mineral zonation of volcaniclastic sediments within the McDermitt caldera complex of Nevada and Oregon  

USGS Publications Warehouse

Volcaniclastic sediments deposited in the moat of the collapsed McDermitt caldera complex have been altered chiefly to zeolites and potassium feldspar. The original rhyolitic and peralkaline ash-flow tuffs are included in conglomerates at the caldera rims and grade into a lacustrine series near the center of the collapse. The tuffs show a lateral zeolitic alteration from almost fresh glass to clinoptilolite, clinoptilolite-mordenite, and erionite; to analcime-potassium feldspar; and finally to potassium feldspar. Vertical zonation is in approximately the same order. Clay minerals in associated mudstones, on the other hand, show little lateral variation but a distinct vertical zonation, having a basal dioctahedral smectite, a medial trioctahedral smectite, and an upper dioctahedral smectite. The medial trioctahedral smectite is enriched in lithium (as much as 6,800 ppm Li). Hydrothermal alteration of the volcaniclastic sediments, forming both mercury and uranium deposits, caused a distinct zeolite and clay-mineral zonation within the general lateral zonation. The center of alteration is generally potassium feldspar, commonly associated with alunite. Potassium feldspar grades laterally and vertically to either clinoptilolite or clinoptilolite-mordenite, generally associated with gypsum. This zone then grades vertically and laterally into fresh glass. The clay minerals are a dioctahedral smectite, a mixed-layer clay mineral, and a 7-A clay mineral. The mixed-layer and 7-A clay minerals are associated with the potassium feldspar-alunite zone of alteration, and the dioctahedral smectite is associated with clinoptilolite. This mineralogical zonation may be an exploration guide for mercury and uranium mineralization in the caldera complex environment.

Glanzman, Richard K.; Rytuba, James J.

1979-01-01

103

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

PubMed Central

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.

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

2002-01-01

104

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

105

Direct electron crystallographic determination of zeolite zonal structures.  

PubMed

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

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

2007-01-01

106

Hydrothermal interactions of cement or mortar with zeolites or montmorillonites  

SciTech Connect

Concretes, grouts, clays and/or zeolites are candidate borehole, shaft or tunnel plugging materials for any nuclear waste repository. Interactions between these plugging materials may take place under mild hydrothermal conditions during the life of a repository. Class H cement or motar (PSU/WES mixture) was reacted with one of two montmorillonites, clinoptilolite or mordenite at 100/sup 0/ and 200/sup 0/C for different periods under a confining pressure of 30 MPa. The solid reaction products were characterized by x-ray powder diffraction and scanning electron microscopy after the hydrothermal treatments. When zeolites were in contact (not intimate mixture) with class H cement, they did not seem to alter but clinoptilolite altered to analcime, and mordenite became poorly crystalline in the presence of mortar (containing NaCl) at both 100/sup 0/ and 200/sup 0/C. When cement or mortar was intimately mixed with zeolites or montmorillonites and reacted hydrothermally, the reaction resulted in the formation of Al substituted tobermorite (11A type) in all cases (this type of reaction is expected at the interface) at both 100/sup 0/ and 200/sup 0/C. The mechanism of tobermorite formation includes the decomposition of zeolites or montmorillonites in the presence of alkaline (pH approx. = 12) cement or mortar and recrystallization to form Al substituted tobermorite. Cesium sorption measurements in 0.01N CaCl/sub 2/ on the reaction products revealed that selective Cs sorption increased in most cases, even though little or none of the original zeolites and montmorillonites remained in the products. For example, Cs sorption K/sub d/ (mL/g) increased from 80 in the untreated mortar + Ca montmorillonite mixture to 1700 in the interaction product which is Al substituted tobermorite. Thus, we discover here that Al substituted tobermorite has good selectivity for Cs.

Komarneni, S.; Roy, D.M.

1983-01-01

107

Studies of anions sorption on natural zeolites.  

PubMed

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

Barczyk, K; Mozgawa, W; Król, M

2014-12-10

108

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

PubMed

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

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

2013-08-28

109

Development of Stable Solidification Method for Insoluble Ferrocyanides-13170  

SciTech Connect

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

Ikarashi, Yuki; Masud, Rana Syed; Mimura, Hitoshi [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba6-6-01-2, Sendai, 980-8579 (Japan)] [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba6-6-01-2, Sendai, 980-8579 (Japan); Ishizaki, Eiji; Matsukura, Minoru [UNION SHOWA K.K. 17-20, Mita 2-chome, Minato-ku, Tokyo 108-0073 (Japan)] [UNION SHOWA K.K. 17-20, Mita 2-chome, Minato-ku, Tokyo 108-0073 (Japan)

2013-07-01

110

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

SciTech Connect

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.

Carlos, B.

1989-02-01

111

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

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.

Mulay, L.N.

1983-11-01

112

Revised mineralogic summary of Yucca Mountain, Nevada  

SciTech Connect

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

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

1989-03-01

113

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.

NONE

1993-12-31

114

Tabulation and evaluation of ion exchange data on smectites, certain zeolites and basalt  

SciTech Connect

An extensive search of the literature has been made for ion exchange data on smectites, certain zeolites and basalt. The data are in the form of thermodynamic equilibrium constants, corrected selectivity coefficients, and distribution coefficients. Room temperature alkali and alkaline earth metal cation ion exchange data for smectites are extensive. Correlation between the exchange free energies of alkali metal cations on Camp Berteau montmorillonite values with their Debeye-Hueckel parameter was found. Significant differences in values of exchange constants for the same reaction on different smectites were noted. While this in part may be attributable to differences in experimental procedures, much of the variance is probably due to differences in charge densities and the effective field strengths of the smectites. Differences in field strength are related to the type and amount of substitution on intercrystalline octahedral and tetrahedral sites. Data on smectites suggest that cation exchange selectivities are very strong functions of temperature. Experiments on the exchange properties of clinoptilolite and mordenite have been generally confined to alkali and alkaline earth cations although data for certain transition metal ions are also available for synthetic mordenite. The temperature dependences of zeolite exchange selectivities remain largely unknown. Distribution coefficients for groundwater-basalt systems have been measured for a variety of elements at temperatures up to 150/sup 0/C. Steady state concentrations are often never achieved either from the sorption or the desorption side. Classical models of ion exchange have been applied successfully to zeolite and smectite exchange reactions. The sorption behavior of a basalt is better treated with models of the interface which take surface ionization and complexation into account.

Benson, L.V.

1980-05-01

115

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

SciTech Connect

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

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

1982-11-01

116

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

USGS Publications Warehouse

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

Bargar, Keith E.; Beeson, Melvin H.

1985-01-01

117

Preliminary Results of Voloxidation Processing of Kilogram Quantities of Used Nuclear Fuel  

SciTech Connect

Advanced nuclear fuel processing methodologies are being studied as part of the Advanced Fuel Cycle Initiative (AFCI) program at ORNL. To support this initiative, processes and equipment were deployed at ORNL to perform all steps in the recycle process on actual used nuclear fuels, ranging from used fuel receipt to production of products and waste forms at the kilogram-scale (with capacity to process 20 kg of used fuel per year in up to four campaigns). In the first campaign, approximately 4 kg of used fuel was processed. As previously reported, the head-end processing was completed using saw-segmented Dresden fuel in lab-scale equipment in multiple batches. The second processing campaign used a new single pin shear and a new bench-scale voloxidizer to perform the dry head-end treatment prior to fuel dissolution. Approximately ~5 kg of used fuel (heavy metal basis) was processed in the second campaign. Two different fuels were oxidized in three separate batches to provide a range of processing conditions. The material used for each batch and general processing conditions are summarized in Table 1. Progress of the oxidation reaction was monitored continuously by two primary measurements; the concentration of oxygen in the effluent stream which was depressed as the oxygen was consumed, and the concentration of krypton-85 in the effluent stream as measured by a gamma counter on the off-gas pipeline. Table 1. Voloxidation test conditions for second campaign. Batch Fuel Source Burnup (GWd/MT)Batch size (kg*)/(kg**)Segment Length (in) Oxidation GasOperation Temperature ( C) 1Surry-2361.223/1.7041.0Air500 2North Anna63 702.071/2.8850.88Air600 3North Anna63 702.012/2.8030.88Oxygen600 * Heavy metal basis. ** Total fuel (oxide + cladding) basis. Fission product gases evolved from the fuel during the oxidation process were trapped for subsequent chemical and radiochemical analysis. The series of traps included a bed of molecular sieves to recover tritium (as HTO), silver-substituted zeolite to capture iodine (e.g. as AgI), a caustic scrubber to collect carbon dioxide (including 14CO2), a hydrogen-substituted mordenite to capture krypton (e.g. 85Kr) by cryogenic temperature swing adsorption, and a silver-substituted mordenite to capture xenon by cryogenic temperature swing absorption. The quantities of these volatile gases collected were compared to ORIGEN calculations to estimate the effectiveness of the voloxidation process to separate the volatiles from the used fuel. This paper will describe the voloxidation system and present preliminary results from the second processing campaign.

Spencer, Barry B [ORNL; DelCul, Guillermo D [ORNL; Jubin, Robert Thomas [ORNL; Owens, R Steven [ORNL; Ramey, Dan W [ORNL; Collins, Emory D [ORNL

2009-01-01

118

Studies of Molecular Dynamics by Solid State Deuterium NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

The rotational dynamics of molecules in a number of solid systems were followed by variable temperature deuterium (^2H), nuclear magnetic resonance (NMR) spectroscopy via changes in the spectral lineshapes and spin-lattice relaxation times (T _1). First the pure solid trimethylamine-borane adduct, (CH_3)_3NBH_3, was studied. For a methyl deuterated sample, T _1 measurements yielded two T_1 minima, 6.9 ms and 4.3 ms corresponding to the slowing of methyl and trimethyl rotation, respectively, with decreasing temperature. Activation energies for methyl and trimethyl rotation, obtained from fitting the T _1 curve as a function of temperature, were 32.8 and 15.0 kJ/mol, respectively; simulations of the spectral lineshapes gave 26.6 and 18.9 kT/mol, respectively. Fitting of the ^2H T_1 curve for the borane deuterated sample gave a BH _3 rotation activation energy of 14.1 kT/mol and a ^2H quadrupolar coupling constant, chi, of 101 kHz. The activation energy for BH_3 rotation obtained from the spectral lineshape simulations gave 12.6 kT/mol. A series of deuterated organic chalcogen cations: (CH_3)_3S^+, (CH_3)_3Se^+ and (CH_3)_3Te^+, were ion exchanged into the cavities of sodium Mordenite LZ-M5 and the dynamics of these guests within the hydrated zeolite were followed by ^2H NMR. All three undergo isotropic motion above about -80 to -90^circC. Below this temperature two superimposed ^2H powder spectra appear; the broad lineshape is consistent with only methyl rotation in a hindered, coordinated site, and the other narrow lineshape is due to both methyl and trimethyl rotation in a less hindered, uncoordinated site. As the temperature is lowered the population of the lower energy coordinated site increases. Relative peak areas yield adsorption enthalpies of 6.7, 7.8 and 10.0 kJ/mol for (CH_3)_3S^+, (CH_3)_3Se^+ and (CH_3)_3Te^+, respectively. The series of methyl deuterated ammonium and phosphonium cations: (CH_3)NH_3^+ , (CH_3)_2NH^+ , (CH_3)_3NH^+ and (CH_3)_4P^+ , were also ion-exchanged into Mordenite. It is shown that these cations also undergo exchange between hindered and unhindered sites. The motion of the cations is strongly influenced by the number of N-H hydrogen bonds available.

Zhao, Baiyi

119

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

PubMed

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

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

2014-06-15

120

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

SciTech Connect

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.

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

1996-04-01

121

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

SciTech Connect

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

Fiddy, Steven [CCLRC Daresbury Laboratory, Daresbury, Warrington, UK, WA4 4AD (United Kingdom); Petranovskii, Vitalii [CCMC-UNAM, Apdo Postal 2681, 22800 Ensenada. B.C., (Mexico); Ogden, Steve [Department of Chemistry, University of Southampton, Southampton (United Kingdom); Iznaga, Inocente Rodriguez [Laboratorio Ingenieria de Zeolitas, Instituto de Materiales y Reactivos (IMRE) - Universidad de la Habana. Zapata y G. s/n. Havana0400 (Cuba)

2007-02-02

122

Savannah River Laboratory monthly report  

SciTech Connect

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

Not Available

1986-02-01

123

Effects of long-term exposure of tuffs to high-level nuclear waste repository conditions. Final report  

SciTech Connect

We have performed exploratory tests to investigate the effects of extended exposure of tuffs from Yucca Mountain, Nevada, to temperatures and pressures similar to those that will be encountered in a high-level nuclear waste repository. In a preliminary report we described statistically significant changes in strength properties and generally minor changes in porosity and grain density. In the present report we describe additional measurements that indicate possible changes in permeability (in one tuff type) after exposure for 2 to 6 months at temperatures from 80 to 180 C, confining pressures of 9.7 and 19.7 MPa, and water pore pressures of 0.5 and 19.7 MPa. Mineralogic examinations have established reactions involving dissolution of silica and feldspar minerals and possible conversion of clinoptilolite to mordenite. We conclude that rock properties important to the operation of a nuclear waste repository in tuff are likely to change over time when exposed to simulated repository conditions, and the details of these time-dependent processes should be investigated further.

Blacic, J.D.; Vaniman, D.T.; Bish, D.L.; Duffy, C.J.; Gooley, R.C.

1986-08-01

124

Alteration patterns in volcanic rocks within an east-west traverse through central Nicaragua  

NASA Astrophysics Data System (ADS)

The volcanic rocks investigated in a cross-section between the Pacific and Atlantic coasts of Nicaragua — with the exception of Recent and some Pleistocene lavas — are incipiently to strongly altered. Alteration patterns on different scales can be discerned in the Tertiary sequences: (i) a regional burial diagenesis or very low-grade burial metamorphism at the low-temperature end of the zeolite facies (mordenite subfacies) with an inferred thermal gradient of < 50°C/km, grading into (ii) a geothermal field type of alteration in mining districts (laumontite subfacies with local transition to wairakite subfacies at depth); the thermal gradient probably exceeded 100°C/km. There are also (iii) local alteration aureoles around gold-bearing quartz veins. The regional alteration assemblages include minerals that, under favorable conditions, might have formed deposits of great potential use as non-metallic raw materials (zeolites and bentonite). Mineralogical differences between the alteration outside and within mining districts might be used as an exploration guide.

Darce, M.; Levi, B.; Nyström, J. O.; Troëng, B.

125

Distribution and volcano-structural control of zeolites and other amygdale minerals in the island of Martinique, F.W.I.  

NASA Astrophysics Data System (ADS)

Zeolites and other amygdale minerals have a widespread occurrence in Martinique. The central and east part of the island is composed of pre-Pliocene submarine formations (hyaloclastitic tuffs, pillow lavas, swarms of dikes, and domes). Here, zeolites occur in about 10 well-defined areas where specific associations constitute discrete zones of progressive metamorphism. Four zones are established which are believed to reflect temperatures ranging from 100 to 200°C. Within the outer zone I, several of the following minerals occur together: heulandite or clinoptilolite, mordenite, chabazite, mesolite; analcime and thomsonite characterize a narrow zone II; stilbite is widespread in zone III, and laumontite characterizes inner zone IV. The Lamentin thermal area is mainly com posed of Recent monogenetic volcanoes (age < 0.7 m.y.) and alluvium overlying pre-Pliocene volcanic rocks. Hot springs (39-51°C) occur in the central part of the area, but the less restricted occurrence of zeolites, calcite and silica, and scattered crystallization of barite, tourmaline, arsenopyrite and bowlingite, emphasize the larger development of recent hydrothermal activity in the area. The distribution of zeolites and other amygdale minerals is not related to regional metamorphism brought about by burial, but rather to areas of well-defined heat flow where suitable fluids were available. Roots of deeply eroded volcanoes, shallow magmatic intrusions, and zones of intensive faulting could have provided the necessary heat required; such structures are referred to in this communications as "heat flow domes".

Westercamp, D.

1981-12-01

126

Radionuclide Leaching from Organic Ion Exchange Resin  

SciTech Connect

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

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

1999-04-02

127

Low sintering temperature glass waste forms for sequestering radioactive iodine  

DOEpatents

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

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

2012-09-11

128

Association of indigo with zeolites for improved color stabilization.  

PubMed

The durability of an organic color and its resistance against external chemical agents and exposure to light can be significantly enhanced by hybridizing the natural dye with a mineral. In search for stable natural pigments, the present work focuses on the association of indigo blue with several zeolitic matrices (LTA zeolite, mordenite, MFI zeolite). The manufacturing of the hybrid pigment is tested under varying oxidizing conditions, using Raman and ultraviolet-visible (UV-Vis) spectrometric techniques. Blending indigo with MFI is shown to yield the most stable composite in all of our artificial indigo pigments. In the absence of defects and substituted cations such as aluminum in the framework of the MFI zeolite matrix, we show that matching the pore size with the dimensions of the guest indigo molecule is the key factor. The evidence for the high color stability of indigo@MFI opens a new path for modeling the stability of indigo in various alumino-silicate substrates such as in the historical Maya Blue pigment. PMID:20925983

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

2010-10-01

129

Association of Indigo with Zeolites for Improved Color Stabilization  

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

130

Biaxial Q-shearing of 27Al 3QMAS NMR spectra: insight into the structural disorder of framework aluminosilicates.  

PubMed

In this contribution, we present the application potentiality of biaxial Q-shearing of (27)Al 3QMAS NMR spectra in the analysis of structural defects of aluminium units in aluminosilicates. This study demonstrates that the combination of various shearing transformations of the recorded (27)Al 3QMAS NMR spectra enables an understanding of the broadening processes of the correlation signals of disordered framework aluminosilicates, for which a wide distribution of (27)Al MAS NMR chemical shifts and quadrupolar parameters (i.e., second-order quadrupolar splitting and quadrupole-induced chemical shifts) can be expected. By combining the suitably selected shearing transformation procedures, the mechanisms of the formation of local defects in aluminosilicate frameworks, including Al/Si substitution effects in the next-nearest neighbouring T-sites, variations in bond angles, and/or variations in the physicochemical nature of charge-balancing counter-ions, can be identified. The proposed procedure has been extensively tested on a range of model aluminosilicate materials (kyanite, ?-alumina, metakaolin, analcime, chabazite, natrolite, phillipsite, mordenite, zeolite A, and zeolite Y). PMID:24333044

Kobera, Libor; Brus, Jiri; Klein, Petr; Dedecek, Jiri; Urbanova, Martina

2014-01-01

131

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

PubMed

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

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

2014-01-01

132

Petrology and hydrothermal mineralogy of US Geological Survey Newberry 2 drill core from Newberry Caldera, Oregon  

USGS Publications Warehouse

USGS Newberry 2 was drilled to a depth of 932 m within Newberry caldera. The bottom-hole temperature of 265??C is the highest reported temperature of any drill hole in the Cascades region of the US. The upper part of the stratigraphic section penetrated by Newberry 2 consists of caldera fill below which are increasingly more mafic lavas ranging from rhyodacite at 501 m to basalt at 932 m. Measured temperatures shallower than 300 m are less than 35??C, and rock alteration consists of hydration of glass and local palagonitization of basaltic tuffs. Incipient zeolitization and partial smectite replacement of ash and pumice occurred of basaltic tuffs. Incipient zeolitization and partial smectite replacement of ash and pumice occurred throughout the pumiceous lithic tuffs from 300 to 500 m. Higher-temperature alteration of the tuffs to chlorite and mordenite occurs adjacent to a rhyodacite sill at 460-470 m; alteration minerals within the sill consist of pyrrhotite, pyrite, quartz, calcite, and siderite. Below 697 m the rocks are progressively more altered with depth mainly because of increased temperature along a conductive gradient from 100??C at 697 m to 265??C at 930 m. -from Authors

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

1988-01-01

133

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

USGS Publications Warehouse

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.

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

1979-01-01

134

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

SciTech Connect

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.

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

1988-09-10

135

Kinetics of silica-phase transitions  

SciTech Connect

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

Duffy, C.J.

1993-07-01

136

Adsorption tests of water vapor on synthetic zeolites for an atmospheric detritiation dryer  

NASA Astrophysics Data System (ADS)

Tritiated hydrogen and hydrocarbon are usually oxidized to a tritiated water vapor to make the tritium adsorbable and easy to treat. The adsorption system as a subsequent process plays an important role in a tritium recovery and its performance affects the overall detritiation efficiency significantly. In order to quantify an adsorbent's utilization and its dynamic capacity against an inlet humidity and a flow rate, a series of quantitative tests based on the breakthrough behavior were carried out in an isothermal fixed bed of synthetic zeolites such as molecular sieve 4A, 5A, 13X and mordenite. The amount of water vapor breaking during the adsorption was estimated to provide a breakthrough capacity at the various inlet flow rates and humidity conditions. The molecular sieve 13X exhibited a better adsorption performance at a given bed height. The existence of CO 2 in a humid atmosphere had a minor effect on the net adsorption capacity and the hydrogen isotopic water (HDO) in the elution stream showed a delayed behavior during a thermal desorption.

Kim, K. R.; Lee, M. S.; Paek, S.; Yim, S. P.; Ahn, D. H.; Chung, H.

2007-08-01

137

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

PubMed

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

Sato, Itaru; Kudo, Hiroaki; Tsuda, Shuji

2011-01-01

138

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

SciTech Connect

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)

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

1981-02-01

139

Simultaneous SO{sub 2}/NO{sub x} abatement using zeolite-supported copper. Progress report, April 1--June 30, 1995  

SciTech Connect

Several catalysts for NO decomposition have been reported in the literature to include the following: Cu/ZSM-5; Cu/Zeolite-Y; Cu/mordenite; Cu/{beta} zeolite; Cu/alumina; and Cu/silica which have been studied less than Cu/ZSM-5. The catalytic properties for NO conversion are found to be different on these samples with the ZSM-5 supported catalysts showing the highest activity in a dry environment free from sulfur oxides. One of the goals of this study is to have a better fundamental understanding on the different roles of Cu and the support in the catalytic reaction. The authors use stable, cationic metal complexes in non-aqueous solvents as sources of the Cu ions in producing model catalysts for which the fate of the source molecule is known and is controlled during the ion exchange/impregnation. Molecular models of these systems can be used to identify the possible configurations of the metal complexes within the zeolite support. The authors compare the performance of the model catalysts to one prepared by aqueous impregnation of ZSM-5 zeolite. The performance of the dinuclear metal complex on silica is compared to the same complex in ZSM-5 and Y-zeolites.

Mitchell, M.B.; White, M.G.

1995-12-31

140

Thermodynamic modeling of natural zeolite stability  

SciTech Connect

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.

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

1997-06-01

141

Status of radioiodine control for nuclear fuel reprocessing plants  

SciTech Connect

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

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

1983-07-01

142

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

SciTech Connect

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.

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

1988-11-01

143

AGING AND IODINE LOADING OF SILVER-FUNCTIONALIZED AEROGELS  

SciTech Connect

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

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

2013-01-01

144

EPR spectra of ?-irradiated DL-?-alanine supported on molecular sieves  

NASA Astrophysics Data System (ADS)

The aim of the work was to collect information concerning boundary effects which are suspected in ?-alanine dosimeters consisted of powdered microcrystalline ?-alanine and binders. In our experiments the conventional binders were replaced by molecular sieves (MS). MS are inorganic porous materials (host structures) with well organized and uniform intra-crystalline pore systems of nano-scale size. The guest molecules can be either physically adsorbed on very large inner MS surface, or chemically bound to the active sites. They can be also encapsulated inside the intracrystalline cavities. The EPR spectra of gamma irradiated DL-?-alanine supported on NaY, CeY, SOD, mordenite, ZSM-5 and ALPO 4-5 were very similar to that one observed for irradiated microcrystalline DL-?-alanine. In the case of alanine supported on HY an initial EPR spectrum was different and only after some weeks it made resemble to the well known quintet observed in microcrystalline samples. In sodalites synthesized in the presence of DL-?-alanine EPR signal appeared in non-irradiated sample was very low and structureless. The irradiated sample showed a distinct spectrum which was quite different from that one observed for crystalline DL-?-alanine.

Peimel-Stuglik, Zofia; Kowalak, Stanis?aw; Jankowska, Aldona

2008-05-01

145

Ion exchange in a zeolite-molten chloride system  

SciTech Connect

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

Woodman, R.H.; Pereira, C. [Argonne National Lab., IL (United States). Chemical Technology Div.

1997-07-01

146

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

PubMed

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

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

2014-01-01

147

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

SciTech Connect

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

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

2013-10-01

148

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

SciTech Connect

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

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

2013-09-01

149

Resonance Raman spectroscopy and DFT calculations of the protonation of 4-(2-pyridylazo)- N, N-dimethylaniline in solution and adsorbed on oxide surfaces  

NASA Astrophysics Data System (ADS)

The protonation of 4-(2-pyridylazo)- N, N-dimethylaniline (PYAD) in aqueous solution and its adsorption on oxide surfaces has been studied by resonance Raman (RR) spectroscopy. The gas phase structures of neutral, protonated and diprotonated forms of PYAD were modelled by SCF-DFT calculations at the B3-LYP/DZ level, enabling determination of the simulated vibrational spectra of these species, together with vibrational assignments, and providing confirmation that protonation occurs initially at the pyridyl nitrogen atom. Electronic absorption spectra were interpreted using time-dependent DFT calculations. Adsorption of PYAD on SiO 2 or Al 2O 3 surfaces is mainly via the neutral species, hydrogen bonded to surface OH groups, although a small proportion of adsorbed molecules are protonated. By contrast, adsorption on SiO 2-Al 2O 3 results in complete protonation, indicating the presence of Brønsted acidic sites with p Ka values ? 4.5, whereas adsorption on H-mordenite results in diprotonation, indicating the presence of Brønsted acidic sites with p Ka values ? 2.

Dines, Trevor J.; MacGregor, Louise D.; Rochester, Colin H.

2006-03-01

150

MOLECULAR SIEVES AS CATALYSTS FOR METHANOL DEHYDRATION IN THE LPDMEtm PROCESS  

SciTech Connect

Several classes of molecular sieves were investigated as methanol dehydration catalysts for the LPDME{trademark} (liquid-phase dimethyl ether) process. Molecular sieves offer a number of attractive features as potential catalysts for the conversion of methanol to DME. These include (1) a wide range of acid strengths, (2) diverse architectures and channel connectivities that provide latitude for steric control, (3) high active site density, (4) well-investigated syntheses and characterization, and (5) commercial availability in some cases. We directed our work in two areas: (1) a general exploration of the catalytic behavior of various classes of molecular sieves in the LPDME{trademark} system and (2) a focused effort to prepare and test zeolites with predominantly Lewis acidity. In our general exploration, we looked at such diverse materials as chabazites, mordenites, pentasils, SAPOs, and ALPOs. Our work with Lewis acidity sought to exploit the structural advantages of zeolites without the interfering effects of deleterious Broensted sites. We used zeolite Ultrastable Y (USY) as our base material because it possesses a high proportion of Lewis acid sites. This work was extended by modifying the USY through ion exchange to try to neutralize residual Broensted acidity.

Andrew W. Wang

2002-04-01

151

Growth of Megaspherulites In a Rhyolitic Vitrophyre  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

152

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

SciTech Connect

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

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

1981-11-01

153

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

SciTech Connect

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.

Suzuki, Y.; Kohyama, N.

1984-10-01

154

Adsorption properties of nitrogen monoxide on silver ion-exchanged zeolites  

SciTech Connect

The removal of nitrogen oxides (NO{sub x}) which cause acid rain and air pollution is an important global environmental problem which needs to be solved soon. The adsorption properties of nitrogen monoxide (NO) on various silver ion-exchanged zeolites were examined by adsorption-desorption measurements in a fixed bed flow apparatus. Both reversible (q{sub rev}) and irreversible (q{sub irr}) adsorption of NO is dependent on the aluminum content in the zeolites and the zeolite structure. The amounts of reversible and irreversible adsorption of NO per silver ion increased with decreasing aluminum content of the zeolites and were constant, independent of the ion exchange level for ZSM-5 zeolites, but increased with the ion exchange level for mordenite zeolites (MOR). It was also found that the adsorption properties are dependent on the temperature and pressure of adsorption: q{sub irr} and q{sub rev} of Ag-MOR increased with decreasing absorption temperature and increasing adsorption pressure. Furthermore, the influence of preadsorbed gases on the Ag-MOR zeolite was investigated, and an enhancement of q{sub rev} was observed when NO{sub 2} was preadsorbed. The NO species adsorbed on the Ag-MOR zeolite were characterized by infrared (IR). Most of the reversibly adsorbed NO species are NO{sup {delta}+} and some N{sub 2}O adsorbed on Ag{sup +}, and the irreversibly adsorbed NO species are some N{sub 2}O, NO{sup {delta}+}, and a small amount of NO{sup {delta}{minus}}, NO{sub 2}{sup {delta}+}.

Zhang, W.; Jia, M.; Yu, J.; Wu, T. [Jilin Univ., Changchun (China). Dept. of Chemistry] [Jilin Univ., Changchun (China). Dept. of Chemistry; Yahiro, Hidenori; Iwamoto, Masakazu [Hokkaido Univ., Sapporo (Japan). Catalysis Research Center] [Hokkaido Univ., Sapporo (Japan). Catalysis Research Center

1999-04-01

155

Adsorption Model for Off-Gas Separation  

SciTech Connect

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

Veronica J. Rutledge

2011-03-01

156

Secondary mineralization and hydrothermal alteration in the Reydarfjordur drill core, eastern Iceland  

NASA Astrophysics Data System (ADS)

Deep crustal drilling in eastern Iceland has allowed study of a fossil hydrothermal system at a constructive plate margin. The drilled sequence consists of partly to completely altered subaerial lava flows, basaltic dikes, and minor clastic material. Alteration and secondary mineralization are most intense in the flow top breccias where water/rock ratios are presumed to have been the highest. In the upper portion of the cored sequence (to a depth of about 1200 m) alteration is characterized by the deposition of clay minerals ± calcite ± quartz ± laumontite into open spaces such as vugs and vesicles. Low-temperature zeolites, such as stilbite, epistilbite, mordenite, and heulandite, are also present but are restricted to the upper 500 m of the drill core. Below 1200 m, alteration is characterized by the dissolution and replacement of both primary minerals and earlier authigenic minerals, followed by partial filling of dissolution cavities. Early mineral assemblages consist of epidote ± quartz ± prehnite ± chlorite ± albite, and a later superimposed assemblage consists of calcite + laumontite ± anhydrite. Authigenic sphene, pyrite, chalcopyrite, pumpellyite, actinolite, and wairakite also occur sporadically in the cored sequence. Secondary mineral assemblages and temperature measurements of fluid inclusions suggest a maximum temperature of alteration of about 300°C. Fluid inclusion compositions indicate that the geothermal fluid was meteoric water with very low salinities and high calcium activities. Iron activities and oxygen fugacities were highest in the deeper portions of the systems. The mineral paragenesis suggests that the fluid composition, temperature, and PCO2 varied significantly with time. The thermal energy for the geothermal system was probably derived from a high-level magma chamber associated with nearby Thingmuli volcano. Local contact metamorphism, indicated by the formation of garnet, occurred during late stage emplacement of dikes into the lava pile. Chlorite ± calcite ± laumontite assemblages were also deposited along subvertical fractures at this time.

Mehegan, James M.; Robinson, Paul T.; Delaney, John R.

1982-08-01

157

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

SciTech Connect

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

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

1999-04-02

158

Zeolite-supported Metal Complexes of Rhodium and of Ruthenium: a General Synthesis Method Influenced by Molecular Sieving Effects  

SciTech Connect

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

Ogino, I.; Chen, C; Gates , B

2010-01-01

159

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

SciTech Connect

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

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

1995-12-01

160

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

SciTech Connect

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.

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

1981-11-01

161

Sorption of cesium and strontium from concentrated brines by backfill barrier materials  

SciTech Connect

The sorption of radionuclides from potentially intruding groundwater at a nuclear waste repository is a major chemical function of backfill barriers. In this study, various materials (including clays, zeolites and an inorganic ion exchanger) were screened for the sorption of the fission products cesium and strontium in concentrated brines. Representative brines A and B for the Waste Isolation Pilot Plant (WIPP), a proposed radioactive waste repository and test facility in bedded salt were used. Sorption properties were quantified using empirical distribution coefficients, k/sub d/. Of the materials examined, sodium titanate had the highest k/sub d/ for the sorption of Sr(II) in both brine A (k/sub d/ = 125 ml/g) and brine B(k/sub d/ = 500 to 600 ml/g). A mordenite-type zeolite was the most effective getter for Cs(I) in brine A (k/sub d = 27 ml/g), while illite yielded the highest k/sub d/ for Cs(I) in brine B (k/sub d/ = 115 ml/g). The relative merit of these k/sub d/ values is evaluated in terms of calculated estimates of breakthrough times for a backfill barrier containing the getter. Results show that a backfill mixture containing these getters is potentially an effective barrier to the migration of Sr(II) and Cs(I), although further study (especially for the sorption of cesium from brine A) is recommended. Initial mechanistic studies revealed competing ion effects which would support an ion exchange mechanism. K/sub d/'s were constant over a Sr(II) concentration range of 10/sup -11/ to 10/sup -5/ M and a Cs(I) concentration range of 10/sup -8/ to 10/sup -5/ M, supporting the choice of a linear sorption isotherm as a model for the results. Constant batch composition was shown to be attained within one week.

Winslow, C D

1981-03-01

162

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

SciTech Connect

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.

WoldeGabriel, G.

1995-02-01

163

Use of coagulant and zeolite to enhance the biological treatment efficiency of high ammonia leachate.  

PubMed

Most landfill leachates in Korea, herein defined as the contaminated liquid resulting from the percolation of water through a landfill, are high in ammonium nitrogen, which inhibits biological treatment processes and deteriorates rivers. A laboratory experiment investigated the effect of pre-removal of ammonium nitrogen using zeolite on the efficiency of organic treatment of the following activated-sludge process. Ferric chloride was initially used as a coagulant for solids removal. A clinoptilolite and mordenite rich rock from the Guryongpo area, the Yeongil Basalt, in Korea, reduced the ammonia nitrogen concentrations of leachate from 1300-1500 to 110-130 mg/l in a 24h batch operation. Three activated sludge reactors were operated to compare treatment efficiency under different influent conditions. In reactor 1, leachate having high concentration of chemical oxygen demands (COD) and suspended solids (SS) was directly fed to the reactor without pretreatment. The supernatant, after the coagulation process that remove some suspended solids and COD, was fed to reactor 2. As the use of coagulation process alone is not effective to remove ammonium nitrogen, supernatant treated by both coagulation focusing on the removal of COD and the zeolite concentrating on the removal of ammonium nitrogen was fed to reactor 3. As the result of experiment, greater efficiency in lowering the chemical oxygen demand (83%, influent COD; 1800-3000 mg/l, effluent COD; 300-500 mg/l) was achieved in reactor 3. Meanwhile, 63% (influent COD; 4000-5000 mg/l, effluent COD; 1470-1840 mg/l) and 66% (influent COD; 2400-3300 mg/l, effluent COD; 820-1100 mg/l) removal efficiency of COD were achieved in reactors 1 and 2, respectively. Thus, ammonia pre-removal by zeolite remarkably improved the lowering of chemical oxygen demand and the solids separation in the activated sludge process. PMID:11846277

Ahn, Dae-Hee; Chung, Yun-Chul; Chang, Won-Seok

2002-01-01

164

Hydrodesulfurization of benzothiophene over zeolite-supported catalysts prepared from Mo and Mo-Ni sulfide clusters  

SciTech Connect

Molybdenum sulfide cluster [Mo{sub 3}S{sub 4}(H{sub 2}O){sub 9}]{sup 4+} and nickel-molybdenum bimetallic sulfide cluster [Mo{sub 3}NiS{sub 4}Cl(H{sub 2}O){sub 9}]{sup 3+} were incorporated into zeolites NaY, HUSY, NaH{beta}, Na-mordenite (NaMOR), and KL by aqueous ion exchange. EXAFS data revealed that the structure of the molybdenum sulfide cluster remained virtually intact after ion exchange. However, the incomplete cubane-type structure of the cluster might be lost after thermal treatment at 573 K. The structure of the cluster in Mo{sub 3}S{sub 4}/NaY and Mo{sub 3}S{sub 4}/KL seems to have changed to the MoS{sub 2}-like structure through the hydrodesulfurization (HDS) reaction, although a considerably high level of dispersion was kept. Mo{sub 3}S{sub 4} cluster catalysts loaded on NaMOR and KL exhibited a higher level of activity for HDS of benzothiophene than Mo{sub 3}S{sub 4} catalysts loaded on the other zeolites. Benzene was formed through acid-catalyzed dealkylation of ethyl-benzene, the primary HDS product. Alkylation of benzothiophene with alkenes derived from the cracking of decane as the solvent also occurred. The acidity seems to be produced through the ion exchange and reduction of cationic clusters during activation. Over HUSY- and NaH{beta}-supported catalysts benzene was the major HDS product. Nickel incorporation into the Mo{sub 3}S{sub 4} zeolite catalysts remarkably enhanced the HDS activity. Introduction of the Mo{sub 3}NiS{sub 4} core into zeolite as a precursor resulted in catalysts with higher HDS activity than that of Mo{sub 3}S{sub 4} core and Ni{sup 2+} independently; it is conceivable that the intimate interaction between nickel and molybdenum in the precursor is effective at producing active species.

Taniguchi, Mitsugu; Imamura, Daichi; Ishige, Hiromi; Ishii, Youichi; Murata, Takashi; Hidai, Masanobu; Tatsumi, Takashi

1999-10-01

165

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

NASA Astrophysics Data System (ADS)

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.

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

2011-06-01

166

Volcaniclastic rocks of the Reydarfjordur drill hole, eastern Iceland: 2. Alteration  

NASA Astrophysics Data System (ADS)

Volcaniclastic rocks of basaltic to rhyolitic composition, interlayered with basaltic to icelanditic lava flows in a 1918-m drill hole in eastern Iceland are altered to zeolite- and pumpellyite-prehnite facies assemblages. Major alteration minerals are chlorites, illite-chlorite mixed minerals, illites, K-feldspar, laumontite, quartz, and sphene; others include julgoldite and secondary allanite. Smectites as well as mordenite and heulandite are restricted to the upper 900 m. Epidote and minor pumpellyite, prehnite, wairakite, and anhydrite are restricted to the core below 900 m. The boundary between zeolite- and prehnite-pumpellyite facies is marked by the appearance of chlorite-epidote-quartz assemblages at around 900 m. The typical paragenesis prehnite-pumpellyite-epidote-chlorite occurs near the base of the drill hole at 1855 m. Textures indicate generally prograde metamorphic conditions. The broad compositional spectrum, ranging from basalt to rhyolite, abundance of vitric fragments, and high initial porosity and permeability of the volcaniclastic rocks were major factors governing alteration. The site of growth (crystal, shard, vesicle, pore, and vein) of a secondary phase strongly influences composition, habit, amount, paragenesis, and time of crystallization. For example, sphene and, to a lesser degree, epidote are less rich in Fe and better crystallized in plagioclase than in the adjacent matrix. The different mineral assemblages developed within plagioclase crystals through the section most clearly reflect the metamorphic changes. The abundance of vitric rhyolitic clasts (shards and pumice) favored K. Al, Si-enriched fluids from which phases like illite and adularia crystallized. These phases were not found in interlayered basalt flows (Mehegan et al., this issue). Low Ca activity is also indicated by the occurrence of wairakite and pumpellyite rather than prehnite, which is common in the basalts. Secular changes during metamorphism in pore fluid composition are shown by zonations in mineral compositions. For example, the depletion of epidote and juldoldite-pumpellyite in Fe with time appears to reflect decreasing ƒo2. Bulk rock chemical changes are more intense in the volcaniclastic rocks compared to the basalt lavas. H2O+, Fe3+/Fe2+ and, in part, CO2 values are higher in the upper part of the hole, reflecting the higher porosity and glass content of the clastic rocks. They decrease markedly downhole, approaching values of the lava flows due to more pervasive metamorphic alteration and thus similar mineral assemblages and physical properties.

Viereck, Lothar G.; Griffin, Brendon J.; Schmincke, Hans-Ulrich; Pritchard, Richard G.

1982-08-01

167

A call to expand regulation to all carcinogenic fibrous minerals  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

168

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

USGS Publications Warehouse

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.

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

1986-01-01

169

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

NASA Astrophysics Data System (ADS)

Phyllosilicates on Mars mapped by infrared spectroscopic techniques could have been affected by dehydration and/or dehydroxylation associated with chemical weathering in hyperarid conditions, volcanism or shock heating associated with meteor impact. The effects of heat-induced dehydration and/or dehydroxylation on the infrared spectra of 14 phyllosilicates from four structural groups (kaolinite, smectite, sepiolite-palygorskite, and chlorite) and two natural zeolites are reported here. Pressed powders of size-separated phyllosilicate and natural zeolite samples were heated incrementally from 100°C to 900°C, cooled to room temperature, and measured using multiple spectroscopic techniques: midinfrared (400-4000 cm-1) attenuated total reflectance, midinfrared reflectance (400-1400 cm-1), and far-infrared reflectance (50-600 cm-1) spectroscopies. Correlated thermogravimetric analysis and X-ray diffraction data were also acquired in order to clarify the thermal transformation of each sample. For phyllosilicate samples, the OH stretching (˜3600 cm-1), OH bending (˜590-950 cm-1), and/or H2O bending (˜1630 cm-1) bands all become very weak or completely disappear upon heating to temperatures > 500°C. The spectral changes associated with SiO4 vibrations (˜1000 cm-1 and ˜500 cm-1) show large variations depending on the compositions and structures of phyllosilicates. The thermal behavior of phyllosilicate IR spectra is also affected by the type of octahedral cations. For example, spectral features of Al3+-rich smectites are more stable than those of Fe3+-rich smectites. The high-temperature (>800°C) spectral changes of trioctahedral Mg2+-rich phyllosilicates such as hectorite, saponite, and sepiolite result primarily from crystallization of enstatite. Phyllosilicates with moderate Mg2+ concentration (e.g., palygorskite, clinochlore) and dioctahedral montmorillonites (e.g., SAz-1 and SCa-3) with partial Mg2+-for-Al3+ substitution all have new spectral feature developed at ˜900 cm-1 upon heating to 800°C. Compared with phyllosilicates, spectral features of two natural zeolites, clinoptilolite and mordenite, are less affected by thermal treatments. Even after heating to 900°C, the IR spectral features attributed to Si (Al)-O stretching and bending vibration modes do not show significant differences from those of unheated zeolites.

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

2011-05-01

170

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

USGS Publications Warehouse

A rhyolitic ash-flow tuff in a hydrothermally active area within the Yellowstone caldera was drilled in 1967, and cores were studied to determine the nature and distribution of primary and secondary mineral phases. The rocks have undergone a complex history of crystallization and hydrothermal alteration since their emplacement 600,000 years ago. During cooling from magmatic temperatures, the glassy groundmass underwent either devitrification to alkali feldspar + ??-cristobalite ?? tridymite or granophyric crystallization to alkali feldspar + quartz. Associated with the zones of granophyric crystallization are prismatic quartz crystals in cavities similar to those termed miarolitic in plutonic rocks. Vapor-phase alkali feldspar, tridymite, magnetite, and sporadic ??-cristobalite were deposited in cavities and in void spaces of pumice fragments. Subsequently, some of the vapor-phase alkali feldspar crystals were replaced by microcrystalline quartz, and the vapor-phase minerals were frosted by a coating of saccharoidal quartz. Hydrothermal minerals occur primarily as linings and fillings of cavities and fractures and as altered mafic phenocrysts. Chalcedony is the dominant mineral related to the present hydrothermal regime and occurs as microcrystalline material mixed with various amounts of hematite and goethite. The chalcedony displays intricate layering and was apparently deposited as opal from silica-rich water. Hematite and goethite also replace both mafic phenocrysts and vapor-phase magnetite. Other conspicuous hydrothermal minerals include montmorillonite, pyrite, mordenite, calcite, and fluorite. Clinoptilolite, erionite, illite, kaolinite, and manganese oxides are sporadic. The hydrothermal minerals show little correlation with temperature, but bladed calcite is restricted to a zone of boiling in the tuff and clearly was deposited when CO2 was lost during boiling. Fractures and breccias filled with chalcedony are common throughout Y-5 and may have been produced by rapid disruption of rock caused by sudden decrease of fluid pressure in fractures, most likely a result of fracturing during resurgent doming in this part of the Yellowstone caldera. The chalcedony probably was deposited as opal or ??-cristobalite from a pre-existing silica floc that moved rapidly into the fractures and breccias immediately after the sudden pressure drop. ?? 1978.

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

1978-01-01

171

Adsorption of amino acids (ALA, CYS, HIS, MET) on zeolites: fourier transform infrared and Raman spectroscopy investigations.  

PubMed

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 [Formula: see text] group, and methionine-zeolite interactions involve the COO, [Formula: see text], and CH(3) 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. PMID:21671763

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

2011-06-01

172

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

SciTech Connect

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

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

2011-12-29

173

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

USGS Publications Warehouse

A continuously cored drill hole designated as USW G-2, located at Yucca Mountain in southwestern Nevada, penetrated 1830.6 m of Tertiary volcanic strata composed of abundant silicic ash-flow tuffs, minor lava and flow breccias, and subordinate volcaniclastic rocks. The volcanic strata penetrated are comprised of the following in descending order: Paintbrush Tuff (Tiva Canyon Member, Yucca Mountain Member, bedded tuff, Pah Canyon Member, and Topopah Spring Member), tuffaceous beds of Calico Hills, Crater Flat Tuff (Prow Pass Member, Bullfrog Member, and Tram unit), lava and flow breccia (rhyodacitic), tuff of Lithic Ridge, bedded and ash-flow tuff, lava and flow breccia (rhyolitic, quartz latitic, and dacitic), bedded tuff, conglomerate and ash-flow tuff, and older tuffs of USW G-2. Comparison of unit thicknesses at USW G-2 to unit thicknesses at previously drilled holes at Yucca Mountain indicate the following: (1) thickening of the Paintbrush Tuff members and tuffaceous beds of Calico Hills toward the northern part of Yucca Mountain; (2) thickening of the Prow Pass Member but thinning of the Bullfrog Member and Tram unit; (3) thinning of the tuff of Lithic Ridge; (4) presence of approximately 280 m of lava and flow breccia not previously penetrated by any drill hole; and (5) presence of an ash-flow tuff unit at the bottom of the drill hole not previously intersected, apparently the oldest unit penetrated at Yucca Mountain to date. Petrographic features of some of the units include: (1) decrease in quartz and K-feldspar and increases in biotite and plagioclase with depth in the tuffaceous beds of Calico Hills; (2) an increase in quartz phenocrysts from the top to the bottom members of the Crater Flat Tuff; (3) a low quartz content in the tuff of Lithic Ridge, suggesting tapping of the magma chamber at quartz-poor levels; (4) a change in zeolitic alteration from heulandite to clinoptilolite to mordenite with increasing depth; (5) lavas characterized by a rhyolitic top and dacitic base, suggesting reverse compositional zoning; and (6) presence of hydrothermal mineralization in the lavas that could be related to an intrusive under Yucca Mountain or to volcanism associated with the Timber Mountain-Claim Canyon caldera complex. A fracture analysis of the core resulted n tabulation of 7,848 fractures, predominately open and high angle. The fractures were filled or coated with material in various combinations and include the following in decreasing abundance: CaCo3, iron oxides and hydroxides, SiO2, manganese oxides and hydroxides, clays and zeolites. An increase in the intensity of fracturing can be correlated with the following: (1) densely welded zones, (2) lithophysal zones, (3) vitrophyre, (4) silicified zones, (5) fault zones, and (6) cooling joints. Numerous fault zones were penetrated by the drill hole, predominately in the lithophysal zone of the Topopah Spring Member and below the tuffaceous beds of Calico Hills. The faults are predominately high angle with both a vertical and lateral component. Three major faults were penetrated, two of which intersect the ground surface, with displacements of at least 20 m and possibly as much as 52 m. The faults and some fractures are probably related to the regional doming of the area associated with the volcanism-tectonism of the Timber Mountain-Claim Canyon caldera complex, and to Basin and Range tectonism.

Maldonado, Florian; Koether, S. L.

1983-01-01

174

Cataclastic rocks of the San Gabriel fault—an expression of deformation at deeper crustal levels in the San Andreas fault zone  

NASA Astrophysics Data System (ADS)

The San Gabriel fault, a deeply eroded late Oligocene to middle Pliocene precursor to the San Andreas, was chosen for petrologic study to provide information regarding intrafault material representative of deeper crustal levels. Cataclastic rocks exposed along the present trace of the San Andreas in this area are exclusively a variety of fault gouge that is essentially a rock flour with a quartz, feldspar, biotite, chlorite, amphibole, epidote, and Fe-Ti oxide mineralogy representing the milled-down equivalent of the original rock (Anderson and Osborne, 1979; Anderson et al., 1980). Likewise, fault gouge and associated breccia are common along the San Gabriel fault, but only where the zone of cataclasis is several tens of meters wide. At several localities, the zone is extremely narrow (several centimeters), and the cataclastic rock type is cataclasite, a dark, aphanitic, and highly comminuted and indurated rock. The cataclastic rocks along the San Gabriel fault exhibit more comminution than that observed for gouge along the San Andreas. The average grain diameter for the San Andreas gouge ranges from 0.01 to 0.06 mm. For the San Gabriel cataclastic rocks, it ranges from 0.0001 to 0.007 mm. Whereas the San Andreas gouge remains particulate to the smallest grain-size, the ultra-fine grain matrix of the San Gabriel cataclasite is composed of a mosaic of equidimensional, interlocking grains. The cataclastic rocks along the San Gabriel fault also show more mineralogiec changes compared to gouge from the San Andreas fault. At the expense of biotite, amphibole, and feldspar, there is some growth of new albite, chlorite, sericite, laumontite, analcime, mordenite (?), and calcite. The highest grade of metamorphism is laumontite-chlorite zone (zeolite facies). Mineral assemblages and constrained uplift rates allow temperature and depth estimates of 200 ± 30° C and 2-5 km, thus suggesting an approximate geothermal gradient of ~50°C/km. Such elevated temperatures imply a moderate to high stress regime for the San Andreas, which is consistent with experimental rock failure studies. Moreover, these results suggest that the previously observed lack of heat flow coaxial with the fault zone may be the result of dissipation rather than low stress. Much of the mineralogy of the cataclastic rocks is still relict from the earlier igneous or metamorphic history of the protolith; porphyroclasts, even in the most deformed rocks, consist of relict plagioclase (oligoclase to andesine), alkali feldspar, quartz, biotite, amphibole, epidote, allanite, and Fe-Ti oxides (ilmenite and magnetite). We have found no significant development of any clay minerals (illite, kaolinite, or montmorillonite). For many sites, the compositions of these minerals directly correspond to the mineral compositions in rock types on one or both sides of the fault. Whole rock major and trace element chemistry coupled with mineral compositions show that mixing within the zone of cataclasis is not uniform, and that originally micaceous foliated, or physically more heterogeneous rock units may contribute a disproportionally large amount to the resultant intrafault material. As previously found for the gouge along the San Andreas, chemical mobility is not a major factor in the formation of cataclastic rocks of the San Gabriel fault. We see only minor changes for Si and alkalies; however, there is a marked mobility of Li, which is a probable result of the alteration and formation of new mica minerals. The gouge of the San Andreas and San Gabriel faults probably formed by cataclastic flow. There is some indication, presently not well constrained, that the fine-grained matrix of the cataclasite of from the San Gabriel fault formed in response to superplastic flow.

Anderson, J. Lawford; Osborne, Robert H.; Palmer, Donald F.

1983-10-01

175

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

SciTech Connect

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)

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)

2013-07-01

176

A thermodynamic and structural study of atomistic, nano and bulk systems  

NASA Astrophysics Data System (ADS)

Atomistic and nanocrystalline materials exhibit significantly different properties than bulk materials. This work aims to compare thermodynamic and structural properties of atomistic, nanocrystalline and bulk materials using high temperature oxide melt drop solution calorimetry, high energy synchrotron X-ray diffraction and computational techniques using molecular mechanics modelling. Oxidative drop solution calorimetry is being developed as a general method for sulfide thermochemistry. Enthalpies of formation (kJ/mol) from the elements (DeltaH°f) are determined for sphalerite (ZnS) (-206.53 +/- 4.03 kJ/mol), galena (PbS) (-98.12 +/- 4.37 kJ/mol), greenockite (hexagonal CdS) (-148.79 +/- 4.13 kJ/mol) and hawleyite (cubic CdS) (-147.65 +/- 4.28 kJ/mol). The enthalpy of formation of hawleyite was determined for the first time. Oxide melt drop solution calorimetry was also developed for selenides. Enthalpies of formation (kJ/mol) from the elements (DeltaH°f) are determined for zinc selenide (ZnSe) (-160.13 +/- 2.91 kJ/mol), lead selenide (PbSe) (-100.83 +/- 4.39 kJ/mol), and cadmium selenide (CdSe) (-138.99 +/- 8.70 kJ/mol). The values for CdSe and PbSe match published data, the DeltaH°f value for CdSe from direct calorimetry is reported for the first time, and a more reliable value for ZnSe is proposed as available data for ZnSe are quite scattered. High-temperature oxide melt solution calorimetry was used to determine the dehydration enthalpy and the formation enthalpy of cationic variants of zeolite beta (Li-BEA, Na-BEA, K-BEA, Rb-BEA and Cs-BEA) from the constituent oxides. The dehydration enthalpy per mole of water decreases in the order Li-BEA > Na-BEA >Cs-BEA > K-BEA >Rb-BEA. Molecular mechanics was used to investigate location of the alkali cations and bonding of water molecules in BEA zeolites. The somewhat smaller dehydration enthalpy of K-BEA can be attributed to weaker cation-water interaction, weaker cation-framework interaction, and absence of framework-water interaction. The enthalpies of formation and dehydration of Li and Na ion exchanged zeolite beta are investigated by high temperature oxide melt solution calorimetry. For Li-BEA, the formation enthalpies of formation from oxides at 25°C are 25.6 +/- 1.7 kJ/mol TO2 for the dehydrated zeolite and -8.45 +/- 0.94 kJ/mol TO2 for the fully hydrated zeolite; for Na-BEA they are -2.4 +/- 0.6 kJ/mol TO2 for the dehydrated and -17.8 +/- 1.0 kJ/mol TO2 for the fully hydrated zeolite. The integral dehydration enthalpy at 25°C is 33.2 +/- 1.8 kJ/mol H2O for Li-BEA and 16.5 +/- 1.1 kJ/mol H2O for Na-BEA. Molecular mechanics simulations explore the cation and water molecule positions in the framework at several water contents. This study presents an analysis of the role of structural water in stabilization of bulk synthetic akaganeite (beta-FeOOH) and compare the structural behavior of bulk and nano akaganeite. Rietveld refinements using synchrotron X-ray powder diffraction data are presented. Akaganeite is, indeed, monoclinic with the Cl atoms located at the center of the tunnels and filling only ˜2.8% of the tunnel sites (0,0,0) in this sample. Structural water and vacancies occupy the remaining tunnel sites. There is no evidence of ordering of water molecules in the tunnels. In nanophase akaganeite, the diffraction pattern shows a mixture of akaganeite and a goethite-like phase. The destruction of the tunnel structure, because of the large fraction of tunnels exposed at the surface of the small particles, leads to the formation of this goethite-like phase, possibly a surface reconstruction on the akaganeite particles. As the particle size increases, the formation of the tunnel structure is complete and the goethite-like phase disappears. The closely balanced energetics of akaganeite and goethite permit this complex crossover in stability, with goethite or goethite-like phases present at small and large, but not intermediate, particle size. The localization and arrangement of thionin blue (C12H 10N3S+) dye molecules in the zeolite mordenite frame

Deore, Suraj Waman