Sample records for zeolite modification copper

  1. Copper-containing zeolite catalysts

    DOEpatents

    Price, Geoffrey L. (Baton Rouge, LA); Kanazirev, Vladislav (Sofia, BG)

    1996-01-01

    A catalyst useful in the conversion of nitrogen oxides or in the synthesis of nitriles or imines from amines, formed by preparing an intimate mechanical mixture of a copper (II)-containing species, such as CuO or CuCl.sub.2, or elemental copper, with a zeolite having a pore mouth comprising 10 oxygen atoms, such as ZSM-5, converting the elemental copper or copper (II) to copper (I), and driving the copper (I) into the zeolite.

  2. Copper-containing zeolite catalysts

    DOEpatents

    Price, G.L.; Kanazirev, V.

    1996-12-10

    A catalyst useful in the conversion of nitrogen oxides or in the synthesis of nitriles or imines from amines, is formed by preparing an intimate mechanical mixture of a copper (II)-containing species, such as CuO or CuCl{sub 2}, or elemental copper, with a zeolite having a pore mouth comprising 10 oxygen atoms, such as ZSM-5, converting the elemental copper or copper (II) to copper (I), and driving the copper (I) into the zeolite.

  3. Zeolite modification II - direct fluorination

    Microsoft Academic Search

    B. M. Lok; F. P. Gortsena; P. J. Izod; C. A. Messina; H. Rastelli

    1982-01-01

    Over the past thirty years, zeolite science has grown into a major branch of chemistry. A large number of new zeolite materials have been made by both direct hydrothermal synthesis and by post-synthesis modification. This has led to a large number of new applications in such diverse fields as catalysis, adsorption and ion exchange. In synthesis alone, over one hundred

  4. Kinetics and thermodynamics of copper ions removal from wastewater by use of zeolite.

    PubMed

    Panayotova, M I

    2001-01-01

    Natural Bulgarian zeolite was tested for its ability to remove Cu2+ from model wastewater. Influence of process variables was investigated. It was found that the optimum wastewater to zeolite ratio is 100:1 and the optimum pH value of water to be treated is 5.5 to 7.5. Zeolite with finer particles shows a higher uptake capacity. The simultaneous presence of Ca2+ and Mg2+ in concentrations similar to their concentrations in Bulgarian natural water does not significantly influence the uptake of Cu2+. Zeolite modification by treating it with NaCl, CH3COONa and NaOH increases its uptake ability. Copper ions are strongly immobilized by modified zeolite and secondary pollution of water caused by its contact with preloaded zeolite is very low (1.5-2.5% of Cu2+ preliminary immobilized have been released back into acidified water). Contacting with 2 mol dm(-3) NaCl can easily regenerate loaded zeolite; best results were obtained for zeolite modified with NaCl. Requirements of Bulgarian standards for industrial wastewater can be met by a one-stage process for an initial Cu2+ concentration of 10 mg dm(-3), and by a two stage process for an initial Cu2+ concentration of 50 mg dm(-3). Uptake of Cu2+ by zeolite from neutral wastewater has proved to be as effective as Cu2+ removal by precipitation of copper hydroxide. The process of Cu2+ uptake by natural zeolite is best described by the kinetic equation for adsorption. This fact, together with the correlation found between the Cu2+ uptake and the amount of Na+, Ca2+ and K+ released into solution by zeolite shows that the ion exchange sorption plays the basic role in Cu2+ uptake by natural zeolite. The value obtained for the apparent activation energy (26.112 kJ mol(-1) implies that the process can be easily carried out with a satisfactory rate. The uptake equilibrium is best described by the Langmuir adsorption isotherm, with Langmuir constants KL= 6.4 x 10(-2) dm3 mg(-1) and M = 6.74 mg g(-1). The apparent equilibrium constant found shows moderate affinity of zeolite for Cu2+. Values of deltaG degrees and deltaH degrees found show the spontaneous and endothermic nature of the process of Cu2+ uptake by natural zeolite. PMID:11530923

  5. Modification of Phenolic Oximes for Copper Extraction 

    E-print Network

    Forgan, Ross Stewart

    2008-01-01

    The thesis deals with the modification of salicylaldoxime-based reagents used in hydrometallurgical extraction, addressing rational ligand design to tune copper(II) extractant strengths and also the development of reagents ...

  6. Copper ion-exchanged zeolite catalysts in deNO x reaction

    Microsoft Academic Search

    Hidenori Yahiro; Masakazu Iwamoto

    2001-01-01

    Copper ion-exchanged zeolites have widely been studied as the catalysts for NOx emission control. Cu-MFI zeolites, especially over-exchanged Cu-MFI, are very active for the catalytic decomposition of NO. The reaction mechanisms and the active sites suggested are summarized. The newly developed selective catalytic reduction of NO with hydrocarbons in the presence of excess oxygen is then introduced. The role of

  7. Desulfurization of Tier 2 gasoline by divalent copper-exchanged zeolite Y

    Microsoft Academic Search

    David L. King; Carlos Faz

    2006-01-01

    The desulfurization of Tier 2 gasoline (<30ppmwS) by divalent copper-exchanged zeolite Y (Cu(II)Y) zeolite was examined. Sulfur removal was found to be greater at 150°C than at lower temperatures for Cu(II)Y adsorbents containing as the secondary cation either Na+ (CuNaY) or H+ (CuHY). Capacities on the order of 60mlgasoline\\/g adsorbent were obtained with both materials before the sulfur concentration in

  8. Production of bimetallic nanowires through electron beam irradiation of copper- and silver-containing zeolite A

    Microsoft Academic Search

    A. Mayoral; P. A. Anderson

    2007-01-01

    Nanowires comprising both silver and copper were synthesized through electron beam irradiation (in a transmission electron microscope) of copper- and silver-containing zeolite A (LTA structure type). The materials were characterized by powder x-ray diffraction, high resolution electron microscopy and energy dispersive x-ray spectroscopy. The thickness of the wires was found to be dependent on the electron beam intensity, and their

  9. Chemisorption of alkenes on copper-exchanged ZSM-5 zeolite

    Microsoft Academic Search

    H. W. Jen; K. Otto

    1994-01-01

    On Cu-ZSM-5 zeolite at room temperature, propane is physisorbed, while propene shows characteristics of chemisorption. The chemisorption mode has certain advantages for the catalytic control of automotive emissions. Alkane and alkene adsorption equilibria and kinetics are compared on Cu-ZSM-5 and on ZSM-5 free of alumina. The results are discussed in terms of the Langmuir adsorption isotherm.

  10. Zeolite-like copper iodide framework with new 6(6) topology.

    PubMed

    Bi, Minghui; Li, Guanghua; Zou, Yongchun; Shi, Zhan; Feng, Shouhua

    2007-02-01

    We have described an unprecedented three-dimensional zeolite-like copper iodide constructed from Cu4I4(DABCO)4 (DABCO = 1,4-diazabicyclo[2.2.2]octane) supertetrahedron units. This compound forms a four-connected network with new 6(6) topology. Its structure reveals one-dimensional channels along the [001] direction, and the framework displays interesting self-penetration. The title compound shows photoluminescence at room temperature in the solid state. PMID:17256998

  11. SlowRelease Zeolite-Bound Zinc and Copper Fertilizers Affect Cadmium Concentration in Wheat and Spinach

    Microsoft Academic Search

    Markus Puschenreiter; Othmar Horak

    2003-01-01

    Cadmium (Cd) accumulation in crops is considered one of the major problems which agriculture faces in industrial and urban areas. This study was conducted to determine the influence of fertilization with slow-release zeolite-bound zinc and copper on the cadmium uptake of wheat (Triticum aestivum L., cv. Nandu) and spinach (Spinacia oleracea L., cv. Matador), two crops with higher tendency to

  12. Kinetics of Copper Adsorption from Effluent Stream by ZeoliteNaX

    NASA Astrophysics Data System (ADS)

    Singh, Surinder; Sambi, S. S.; Sharma, S. K.; Pandey, Pankaj Kumar

    2010-06-01

    The batch experiments were conducted to study the copper (II) removal by ZeoliteNaX at temperature of 288+1 K, adsorbent dose of 2 g/L and contact time of 24 hour. Effects of pH, temperature, contact time and Cu (II) ion concentration by the adsorbent were investigated. The data were analyzed using the Langmuir, Freundlich and Temkin isotherms. Freundlich isotherm was found to correlate the adsorption of Cu (II) better and the mono-layer adsorption capacity for Cu (II) removal was 41.6 mg/g. The adsorbed amounts of Cu (II) reached equilibrium within 150 minutes. The four adsorption kinetic models namely, the first order equation, second order equations, pseudo-first order equation and pseudo second-order equations were also tested to fit the data. The pseudo-first-order equation was found to fit best for the experimental data. Thermodynamic analysis indicated the spontaneous and endothermic nature of the adsorption of Cu (II) by ZeoliteNaX.

  13. Evaluation of the bactericidal characteristics of nano-copper oxide or functionalized zeolite coating for bio-corrosion control in concrete sewer pipes

    Microsoft Academic Search

    T. Haile; G. Nakhla; E. Allouche; S. Vaidya

    2010-01-01

    The bactericidal characteristics of nano-copper oxide or functionalized zeolite coated concrete pipes against Acidithiobacillus thiooxidans were studied by measuring the temporal variation of bacterial dry cell weight measurement, cellular Adenosine Triphosphate production, as well as oxygen uptake rate of the aforementioned bacterium. Uncorroded (UC), severely corroded (SC), and moderately corroded (MC) concrete pipes were electrochemically coated with a nano-copper oxide,

  14. Screening of optimum condition for combined modification of ultra-stable Y zeolites using multi-hydroxyl carboxylic acid and phosphate

    Microsoft Academic Search

    Xing-wen Chang; Li-feng He; Hai-ning Liang; Xin-mei Liu; Zi-feng Yan

    2010-01-01

    According to the performance requirements of hydrocracking catalyst with high selectivity to middle distillate, multi-hydroxyl carboxylic acid (MHCA) and phosphate (AP) were used to achieve combined dealuminum modification of ultra-stable Y zeolites. The modification effect was influenced by the concentration of MHCA and AP, liquid–liquid ratio, reaction temperature and reaction time. In order to find the optimum modification condition, orthogonal

  15. Modification of surface properties of copper-refractory metal alloys

    DOEpatents

    Verhoeven, John D. (Ames, IA); Gibson, Edwin D. (Ames, IA)

    1993-10-12

    The surface properties of copper-refractory metal (CU-RF) alloy bodies are modified by heat treatments which cause the refractory metal to form a coating on the exterior surfaces of the alloy body. The alloys have a copper matrix with particles or dendrites of the refractory metal dispersed therein, which may be niobium, vanadium, tantalum, chromium, molybdenum, or tungsten. The surface properties of the bodies are changed from those of copper to that of the refractory metal.

  16. Copper (II) phthalocyanines immobilized on alumina and encapsulated inside zeolite-X and their applications in photocatalytic degradation of cyanide: A comparative study

    Microsoft Academic Search

    R. M. Mohamed; Mohamed Mokhtar Mohamed

    2008-01-01

    Copper phthalocyanine (CuPc) complexes either deposited on alumina (CuPc\\/Al); synthesized by sol–gel, or encapsulated inside zeolite-X (CuPc\\/ZX) while in situ synthesis were characterized by X-ray diffraction (XRD), DSC, FT-IR, diffuse reflectance UV–vis, dynamic light scattering and N2 adsorption techniques. These materials were tested for photocatalytic oxidation of cyanide in comparison with ZX and CuPc free complex. Unlike the case on

  17. Natrolite zeolite supported copper nanoparticles as an efficient heterogeneous catalyst for the 1,3-diploar cycloaddition and cyanation of aryl iodides under ligand-free conditions.

    PubMed

    Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Khalaj, Mehdi

    2015-09-01

    In this paper, we report the preparation of Natrolite zeolite supported copper nanoparticles as a heterogeneous catalyst for 1,3-diploar cycloaddition and synthesis aryl nitriles from aryl iodides under ligand-free conditions. The catalyst was characterized using XRD, SEM, TEM, EDS and TG-DTA. The experimental procedure is simple, the products are formed in high yields and the catalyst can be recycled and reused several times without any significant loss of catalytic activity. PMID:25988488

  18. Tschortnerite, a copper-bearing zeolite from the Bellberg volcano, Eifel, Germany

    Microsoft Academic Search

    H. EFFENBERGER; G. GIESTER; W. KRAUSE; H.-J. BERNHARDT

    Single-crystal X-ray investigations showed that tschortnerite is a zeolite; the structure contains interconnection of double six-rings, double eight-rings, sodalite cages, truncated cubo-octahedra, and previously unknown 96-mem- bered cages (tschortnerite cage). A new structural unit is the (Cu 12(OH)24)Ca8O24(H2O)8 cluster centered within the truncated cubo-octahedron. The cluster is formed by a rhomb- dodecahedron-like arrangement of corner connected CuO4 squares, the eight

  19. Inhibitory effects of aromatic herbs on lipid peroxidation and protein oxidative modification by copper.

    PubMed

    Toda, Shizuo

    2003-05-01

    Aromatic herbs have been used as carminatives. Oxygen free radicals are generated in ischaemia/reperfusion injury in the stomach, and induce lipid peroxidation or protein oxidative modification. Several aromatic herbs were shown to have inhibitory effects on the generation of oxygen free radicals. It was shown that several aromatic herbs, Caryophylli Flos, Cinnamomi Cortex, Foeniculi Fructus and Zedoariae Rhizoma, have inhibitory effects on lipid peroxidation or protein oxidative modification by copper. PMID:12748995

  20. Modification of commercial NaY zeolite to give high water diffusivity and adsorb a large amount of water.

    PubMed

    Katoh, Masahiro; Kimura, Michisato; Sugino, Mao; Horikawa, Toshihide; Nakagawa, Keizo; Sugiyama, Shigeru

    2015-10-01

    By using NaY zeolites as desiccant materials, commercial NaY zeolite was alkali treated with 1M NaOH aqueous solution and then Mg(2+) ion-exchanged by 0.5M Mg(NO3)2 aqueous solution. Alkali treatment (AT) of NaY zeolite removed silicon atoms selectivity from the framework of Y-type zeolite and enhanced water diffusivity of Y-type zeolite. On the other hand, Mg(2+) ion-exchange of NaY zeolite increased the amount of water adsorbed. Prepared Y-AT-Mg zeolite had both water adsorption velocity and a large difference of water adsorbed amount between adsorption at 30°C and desorption at 100°C. PMID:26072446

  1. Topotactic conversion of ?-helix-layered silicate into AST-type zeolite through successive interlayer modifications.

    PubMed

    Asakura, Yusuke; Takayama, Ryosuke; Shibue, Toshimichi; Kuroda, Kazuyuki

    2014-02-10

    AST-type zeolite with a plate morphology can be synthesized by topotactic conversion of a layered silicate (?-helix-layered silicate; HLS) by using N,N-dimethylpropionamide (DPA) to control the layer stacking of silicate layers and the subsequent interlayer condensation. Treatment of HLS twice with 1)?hydrochloric acid/ethanol and 2)?dimethylsulfoxide (DMSO) are needed to remove interlayer hydrated Na ions and tetramethylammonium (TMA) ions in intralayer cup-like cavities (intracavity TMA ions), both of which are introduced during the preparation of HLS. The utilization of an amide molecule is effective for the control of the stacking sequence of silicate layers. This method could be applicable to various layered silicates that cannot be topotactically converted into three-dimensional networks by simple interlayer condensation by judicious choice of amide molecules. PMID:24431158

  2. Localized corrosion effects and modifications of acidic and alkaline slurries on copper chemical mechanical polishing

    NASA Astrophysics Data System (ADS)

    Tsai, Tzu-Hsuan; Yen, Shi-Chern

    2003-04-01

    This study demonstrates the CMP performance can be enhanced by modifying the corrosion effects of acidic and alkaline slurries on copper. A corrosion test-cell with a polishing platform is connected with the potentiostat to investigate the corrosion behaviors of copper CMP in various alumina slurries. Experiments show that the slurry needs to be maintained in acidic pH<4.56 or alkaline pH>9.05 surroundings and thus better dispersion of alumina particles and less residual contaminant on copper surface can be obtained. The surface defects after copper CMP using acidic and alkaline slurries are described by pitting corrosion mechanisms, and these mechanisms can be regarded as a basis to modify their corrosion effects. Experimental results indicate that it is necessary to modify the dissolution of HNO 3 and oxidization of NH 4OH for copper CMP slurries. Consequently, the slurries of 5 wt.% HNO 3 by adding 0.1 wt.% BTA or 5 wt.% KNO 3 by adding 1 wt.% NH 4OH achieve good CMP performance for copper with higher CMP efficiency factor (CMPEF), 1460 and 486, and lower surface roughness ( Rq), 4.019 and 3.971 nm, respectively. It is found that AFM micrographs can support the effectiveness of corrosion modifications for copper CMP in various slurry chemistries.

  3. Process for producing zeolite adsorbent and process for treating radioactive liquid waste with the zeolite adsorbent

    SciTech Connect

    Motojima, K.; Kawamura, F.

    1984-05-15

    Zeolite is contacted with an aqueous solution containing at least one of copper, nickel, cobalt, manganese and zinc salts, preferably copper and nickel salts, particularly preferably copper salt, in such a form as sulfate, nitrate, or chloride, thereby adsorbing the metal on the zeolite in its pores by ion exchange, then the zeolite is treated with a water-soluble ferrocyanide compound, for example, potassium ferrocyanide, thereby forming metal ferrocyanide on the zeolite in its pores. Then, the zeolite is subjected to ageing treatment, thereby producing a zeolite adsorbent impregnated with metal ferrocyanide in the pores of zeolite. The adsorbent can selectively recover cesium with a high percent cesium removal from a radioactive liquid waste containing at least radioactive cesium, for example, a radioactive liquid waste containing cesium and such coexisting ions as sodium, magnesium, calcium and carbonate ions at the same time at a high concentration. The zeolite adsorbent has a stable adsorbability for a prolonged time.

  4. Oxidative modification of aldose reductase induced by copper ion. Factors and conditions affecting the process.

    PubMed

    Cecconi, I; Moroni, M; Vilardo, P G; Dal Monte, M; Borella, P; Rastelli, G; Costantino, L; Garland, D; Carper, D; Petrash, J M; Del Corso, A; Mura, U

    1998-10-01

    Bovine lens aldose reductase (ALR2) is inactivated by copper ion [Cu(II)] through an oxygen-independent oxidative modification process. A stoichiometry of 2 equiv of Cu(II)/enzyme mol is required to induce inactivation. While metal chelators such as EDTA or o-phenantroline prevent but do not reverse the ALR2 inactivation, DTT allows the enzyme activity to be rescued by inducing the recovery of the native enzyme form. The inactive enzyme form is characterized by the presence of 2 equiv of bound copper, at least one of which present as Cu(I), and by the presence of two lesser equivalents, with respect to the native enzyme, of reduced thiol residues. Data are presented which indicate that the Cu-induced protein modification responsible for the inactivation of ALR2 is the generation on the enzyme of an intramolecular disulfide bond. GSH significantly interferes with the Cu-dependent inactivation of ALR2 and induces, through its oxidation to GSSG, the generation of an enzyme form linked to a glutathionyl residue by a disulfide bond. PMID:9760253

  5. Managing ammonia emissions from dairy cows by amending slurry with alum or zeolite or by diet modification.

    PubMed

    Meisinger, J J; Lefcourt, A M; Van Kessel, J A; Wilkerson, V

    2001-10-27

    Animal agriculture is a significant source of atmospheric ammonia. Ammonia (NH3) volatilization represents a loss of plant available N to the farmer and a potential contributor to eutrophication in low-nitrogen input ecosystems. This research evaluated on-farm slurry treatments of alum or zeolite and compared three diets for lactating dairy cows in their effectiveness to reduce NH3 emissions. NH3 emissions were compared using a group of mobile wind tunnels. The addition of 2.5% alum or 6.25% zeolite to barn-stored dairy slurry reduced NH3 volatilization by 60% and 55%, respectively, compared to untreated slurry. The alum conserved NH3 by acidifying the slurry to below pH 5, while the zeolite conserved ammonia by lowering the solution-phase nitrogen through cation exchange. The use of alum or zeolite also reduced soluble phosphorus in the slurry. NH3 loss from fresh manure collected from lactating dairy cows was not affected by three diets containing the same level of crude protein but differing in forage source (orchardgrass silage vs. alfalfa silage) or neutral detergent fiber (NDF) content (30% vs. 35% NDF). NH3 losses from the freshly excreted manures occurred very rapidly and included the urea component plus some unidentified labile organic nitrogen sources. NH3 conservation strategies for fresh manures will have to be active within the first few hours after excretion in order to be most effective. The use of alum or zeolites as an on-farm amendment to dairy slurry offers the potential for significantly reducing NH3 emissions. PMID:12805887

  6. Comparison between copper-mediated and hypochlorite-mediated modifications of human low density lipoproteins evaluated by protein carbonyl formation

    Microsoft Academic Search

    Liang-Jun Yan; John K. Lodge; Maret G. Traber; Seiichi Matsugo; Lester Packer

    The purpose of this study was to evaluate the mech- anisms of apolipoprotein B (apoB) modification during oxi- dation of human low density lipoproteins (LDL) mediated ei- ther by copper or by hypochlorite (HOCl). The kinetics of protein carbonyl formation, the relationship of apoB carbonyl formation to lipid peroxidation, and the loss of apoB lysine residues were determined. During copper-mediated

  7. Orthogonal Experiment of Modified Zeolite for Wastewater Treatment

    Microsoft Academic Search

    Zuo Jinlong

    2010-01-01

    In order to improve ammonia removal capability from wastewater, zeolite was modified in this paper. Some results for virgin zeolite were revealed by SEM, and its structure showed some ions such NH4+ enter into the pore way in the zeolite. The best results could be attained by combined modification with orthogonal experiment. The adsorption capacity of modified zeolite could be

  8. Simultaneous SO{sub 2}/NO{sub x} abatement using zeolite-supported copper. Progress report, October 1, 1992--December 31, 1992

    SciTech Connect

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

    1994-09-01

    The proposed research seeks to advance/improve current flue gas cleanup catalyst technology by modifying promising copper-exchanged zeolite NO decomposition catalysts which reduce NO to elemental nitrogen and oxygen in the absence of an added reducing gas. The authors believe that this approach has great potential. Copper on alumina has been investigated by the Pittsburgh Energy Technology Center (PETC) as a NO{sub x}/SO{sub 2} abatement catalyst. Copper on alumina acts as a sorbent for SO{sub 2}, forming a surface sulfate upon adsorption in an oxygen-containing atmosphere, and as a catalyst for selective catalytic reduction (SCR) of NO{sub x} using ammonia; both CuO and CuSO{sub 4} on the surfaces of these materials are active SCR catalysts. SO{sub 2} adsorption in the PETC studies was carried out at 673K, a temperature well within the range for active NO decomposition by the Cu-ZSM-5 catalyst. The authors believe that by beginning with a material which decomposes NO without needing an added reducing gas, they will be able to design a catalyst which will act as a regenerable NO{sub x}/SO{sub 2} abatement catalyst which does not need ammonia to accomplish NO{sub x} reduction, and which will accomplish SO{sub 2} abatement by adsorption, similar to the copper on alumina catalyst. Coupled with a SO{sub 2} oxidation catalyst, this successful system will be able to remove both NO{sub x} and SO{sub 2} from flue gases with no added reducing agent and no waste.

  9. Simultaneous SOâ\\/NOâ abatement using zeolite-supported copper. Quarterly progress report, January 1, 1995March 31, 1995

    Microsoft Academic Search

    M. B. Mitchell; M. G. White

    1995-01-01

    We have significantly improved on our earlier results with a copper-impregnated alumina, obtaining reproducible results for the impregnation procedure and linear behavior with solution concentration of the precursor. The copper acetylacetonate precursor is adsorbed molecularly onto the alumina surface, with no noticeable decomposition. The adsorbed complex appears to form layers on the alumina surface, similar to results found using the

  10. Thermal behavior of natural zeolites

    SciTech Connect

    Bish, D.L.

    1993-09-01

    Thermal behavior of natural zeolites impacts their application and identification and varies significantly from zeolite to zeolite. Zeolites evolve H{sub 2}0 upon heating, but recent data show that distinct ``types`` of water (e.g., loosely bound or tightly bound zeolitic water) do not exist. Rather water is bound primarily to extra-framework cations with a continuum of energies, giving rise to pseudocontinuous loss of water accompanied by a dynamic interaction between remaining H{sub 2}0 molecules and extra-framework cations. These interactions in the channels of zeolites give rise to dehydration dependent on the extra-framework cation, in addition to temperature and water vapor pressure. The dehydration reaction and the extra-framework cation also affect the thermal expansion/contraction. Most zeolites undergo dehydration-induced contractions that may be anisotropic, although minor thermal expansion can be seen with some zeolites. Such contractions can be partially or completely irreversible if they involve modifications of the tetrahedral framework and/or if rehydration is sluggish. Thermally induced structural modifications are also driven initially by dehydration and the concomitant contraction and migration of extra-framework cations. Contraction is accommodated by rotations of structural units and tetrahedral cation-oxygen linkages may break. Thermal reactions that involve breaking of tetrahedral cation-oxygen bonds markedly irreversible and may be kinetically limited, producing large differences between short- and long-term heating.

  11. Erosion and Modifications of Tungsten-Coated Carbon and Copper Under High Heat Flux

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; S, Tamura; K, Tokunaga; N, Yoshida; Zhang, Fu; Xu, Zeng-yu; Ge, Chang-chun; N, Noda

    2003-08-01

    Tungsten-coated carbon and copper was prepared by vacuum plasma spraying (VPS) and inert gas plasma spraying (IPS), respectively. W/CFC (Tungsten/Carbon Fiber-Enhanced material) coating has a diffusion barrier that consists of W and Re multi-layers pre-deposited by physical vapor deposition on carbon fiber-enhanced materials, while W/Cu coating has a graded transition interface. Different grain growth processes of tungsten coatings under stable and transient heat loads were observed, their experimental results indicated that the recrystallizing temperature of VPS-W coating was about 1400 °C and a recrystallized columnar layer of about 30 ?m thickness was formed by cyclic heat loads of 4 ms pulse duration. Erosion and modifications of W/CFC and W/Cu coatings under high heat load, such as microstructure changes of interface, surface plastic deformations and cracks, were investigated, and the erosion mechanism (erosion products) of these two kinds of tungsten coatings under high heat flux was also studied.

  12. COPPER

    EPA Science Inventory

    The report is a review of current knowledge of the distribution of copper in the environment and living things. Metabolism and the effects of copper in the biosphere are also considered. Copper compounds are common and widely distributed in nature. They are also extensively mined...

  13. Can Dynamics Be Responsible for the Complex Multipeak Infrared Spectra of NO Adsorbed to Copper(II) Sites in Zeolites?

    PubMed

    Göltl, Florian; Sautet, Philippe; Hermans, Ive

    2015-06-26

    Copper-exchanged SSZ-13 is a very efficient material in the selective catalytic reduction of NOx using ammonia (deNOx -SCR) and characterizing the underlying distribution of copper sites in the material is of prime importance to understand its activity. The IR spectrum of NO adsorbed to divalent copper sites are modeled using ab?initio molecular dynamics simulations. For most sites, complex multi-peak spectra induced by the thermal motion of the cation as well as the adsorbate are found. A finite temperature spectrum for a specific catalyst was constructed, which shows excellent agreement with previously reported data. Additionally these findings allow active and inactive species in deNOx -SCR to be identified. To the best of our knowledge, this is the first time such complex spectra for single molecules adsorbed to single active centers have been reported in heterogeneous catalysis, and we expect similar effects to be important in a large number of systems with mobile active centers. PMID:25966680

  14. Modification of poly(tetrafluoroethylene) and copper foil surfaces by graft polymerization for adhesion improvement

    Microsoft Academic Search

    J. Z. Wu; E. T. Kang; K. G. Neoh; C. Q. Cui; T. B. Lim

    2000-01-01

    Thermal graft polymerization-induced lamination of surface-modified copper foil to surface-modified poly(tetrafluoroethylene) (PTFE) film was achieved in the presence of an epoxy resin adhesive and glycidyl methacrylate (GMA) monomer, or in the presence of GMA and hexamethylenediamine (HEDA). The copper foil surfaces were pretreated with an organosilane coupling agent (SCA), such as (3-mercaptopropyl)trimethoxysiane, 3-(trimethoxysilyl)propyl methacrylate, or N1-[3-(trimethoxysilyl)propyl]diethylene-triamine. The silanized copper foils

  15. Modification of vapor sensitivity in ellipsometric gas sensing by copper deposition in porous silicon

    Microsoft Academic Search

    Guoliang Wang; Hans Arwin

    2002-01-01

    The sensitivities of porous silicon layers modified by copper deposition to low vapor concentrations of methanol, ethanol and 2-propanol are studied with spectroscopic ellipsometry. The porous silicon layers are prepared with electrochemical etching in hydrofluoric acid, and copper deposition is done in aqueous CuSO4. The ellipsometric vapor sensitivities, in terms of the ellipsometric spectral shifts due to gas exposures, of

  16. Oxidative modification of aldose reductase induced by copper ion. Definition of the metal-protein interaction mechanism.

    PubMed

    Cecconi, Ilaria; Scaloni, Andrea; Rastelli, Giulio; Moroni, Maria; Vilardo, Pier Giuseppe; Costantino, Luca; Cappiello, Mario; Garland, Donita; Carper, Deborah; Petrash, J Mark; Del Corso, Antonella; Mura, Umberto

    2002-11-01

    Aldose reductase (ALR2) is susceptible to oxidative inactivation by copper ion. The mechanism underlying the reversible modification of ALR2 was studied by mass spectrometry, circular dichroism, and molecular modeling approaches on the enzyme purified from bovine lens and on wild type and mutant recombinant forms of the human placental and rat lens ALR2. Two equivalents of copper ion were required to inactivate ALR2: one remained weakly bound to the oxidized protein whereas the other was strongly retained by the inactive enzyme. Cys(303) appeared to be the essential residue for enzyme inactivation, because the human C303S mutant was the only enzyme form tested that was not inactivated by copper treatment. The final products of human and bovine ALR2 oxidation contained the intramolecular disulfide bond Cys(298)-Cys(303). However, a Cys(80)-Cys(303) disulfide could also be formed. Evidence for an intramolecular rearrangement of the Cys(80)-Cys(303) disulfide to the more stable product Cys(298)-Cys(303) is provided. Molecular modeling of the holoenzyme supports the observed copper sequestration as well as the generation of the Cys(80)-Cys(303) disulfide. However, no evidence of conditions favoring the formation of the Cys(298)-Cys(303) disulfide was observed. Our proposal is that the generation of the Cys(298)-Cys(303) disulfide, either directly or by rearrangement of the Cys(80)-Cys(303) disulfide, may be induced by the release of the cofactor from ALR2 undergoing oxidation. The occurrence of a less interactive site for the cofactor would also provide the rationale for the lack of activity of the disulfide enzyme forms. PMID:12183464

  17. Nitric oxide adsorbed on zeolites: EPR studies

    NASA Astrophysics Data System (ADS)

    Yahiro, Hidenori; Lund, Anders; Shiotani, Masaru

    2004-05-01

    CW-EPR studies of NO adsorbed on sodium ion-exchanged zeolites were focused on the geometrical structure of NO monoradical and (NO) 2 biradical formed on zeolites. The EPR spectrum of NO monoradical adsorbed on zeolite can be characterized by the three different g-tensor components and the resolved y-component hyperfine coupling with the 14N nucleus. Among the g-tensor components, the value of g zz is very sensitive to the local environment of zeolite and becomes a measure of the electrostatic field in zeolite. The temperature dependence of the g-tensor demonstrated the presence of two states of the Na-NO adduct, in rigid and rotational states. The EPR spectra of NO adsorbed on alkaline metal ion-exchanged zeolite and their temperature dependency are essentially the same as that on sodium ion-exchanged zeolite. On the other hand, for NO adsorbed on copper ion-exchanged zeolite it is known that the magnetic interaction between NO molecule and paramagnetic copper ion are observable in the spectra recorded at low temperature. The signals assigned to (NO) 2 biradical were detected for EPR spectrum of NO adsorbed on Na-LTA. CW-EPR spectra as well as their theoretical calculation suggested that the two NO molecules are aligned along their N?O bond axes. A new procedure for automatical EPR simulation is described which makes it possible to analyze EPR spectrum easily. In the last part of this paper, some instances when other nitrogen oxides were used as a probe molecule to characterize the zeolite structure, chemical properties of zeolites, and dynamics of small molecules were described on the basis of selected literature data reported recently.

  18. Efficient modification of Cu electrode with nanometer-sized copper tetracyanoquinodimethane for high performance organic field-effect transistors.

    PubMed

    Di, Chong-an; Yu, Gui; Liu, Yunqi; Guo, Yunlong; Wu, Weiping; Wei, Dacheng; Zhu, Daoben

    2008-05-01

    We report high performance organic field-effect transistors (OFETs) with the modified Cu bottom-contact electrodes. Efficient modification of the Cu electrodes with nanometer-size copper tetracyanoquinodimethane (Cu-TCNQ) increases the electrode/organic layer contact area and reduces contact resistance. We investigated the effect of the Cu-TCNQ morphology on the device performance. The pentacene-based OFETs with the modified Cu bottom-contact electrodes exhibited high device performance. The field-effect mobility up to 0.31 cm(2)/V s was achieved. To the best of our knowledge, this is the highest device performance for the OFETs with the bottom Cu electrodes ever reported. Consequently, our results provide an effective approach to fabricate high performance and low-cost OFETs. PMID:18414721

  19. Kinetics of zeolite dealumination in steam

    SciTech Connect

    Hughes, C.D.; Labouriau, A.; Crawford, S.N.; Romero, R.; Quirin, J.; Earl, W.L.

    1998-08-01

    Zeolite dealumination is a well known phenomenon that contributes to the deactivation or activation of catalysts in several different applications. The most obvious effect is in acid catalysis where dealumination under reaction conditions removes the Broensted sites, thus deactivating the catalyst. The authors are interested in the use of cation exchanged zeolites as selective reduction catalysts for removal of NO{sub x} from exhaust streams, particularly from automotive exhaust. In this case, copper exchanged ZSM-5 has been shown to be an effective catalyst for the generic reaction of NO{sub x} with hydrocarbons. However, high temperature and steam in combustion exhaust causes dealumination and consequent migration of copper out of the zeolite structure resulting in rapid deactivation of the catalyst. Dealumination of zeolites has been reported by many authors in uncountable papers and cannot be reviewed here. However, to the authors` knowledge there are no reports on the kinetics of dealumination under varying conditions of temperature and steam. By measuring the kinetics of dealumination with different zeolites and exchange cations they expect to develop working models of the dealumination process that will allow control of zeolite deactivation. This manuscript is a description of the basic techniques used and a progress report on the very beginning of this study.

  20. Modified zeolites as catalysts in the Friedel-Crafts acylation

    Microsoft Academic Search

    Kristin Gaare; Duncan Akporiaye

    1996-01-01

    Modified zeolites were found to be active catalysts in the Friedel-Crafts acylation of anisole by acetyl chloride and acetic anhydride. The effect of two different modifications of the zeolites were tested; lanthanum-exchange and varying the SiAl ratio. For the rare-earth modified zeolites, the activity was found to be dependent on the lanthanum content, and the yield increased with the level

  1. Simultaneous SO{sub 2}/NO{sub x} abatement using zeolite-supported copper. Quarterly progress report, January 1, 1995--March 31, 1995

    SciTech Connect

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

    1995-12-01

    We have significantly improved on our earlier results with a copper-impregnated alumina, obtaining reproducible results for the impregnation procedure and linear behavior with solution concentration of the precursor. The copper acetylacetonate precursor is adsorbed molecularly onto the alumina surface, with no noticeable decomposition. The adsorbed complex appears to form layers on the alumina surface, similar to results found using the same complex with a silica substrate. The materials start out as light blue powders, and after oxidation are light green. Using infrared spectroscopy, we have examined the in situ adsorption and oxidation of SO{sub 2} on the oxidized sorbent, which is dispersed copper oxide supported on aluminum oxide, and have observed that the initial species formed correspond to aluminum sulfate and aluminum sulfate. The sulfate is formed at temperatures much lower than similar experiments studying SO{sub 2} adsorption on alumina and sodium-doped alumina. As a result of oxidation, the adsorbed sulfur species, which begin as aluminum sulfate and sulfate, are converted to copper sulfate.

  2. Metal Oxide/Zeolite Combination Absorbs H2S

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E.; Sharma, Pramod K.

    1989-01-01

    Mixed copper and molybdenum oxides supported in pores of zeolite found to remove H2S from mixture of gases rich in hydrogen and steam, at temperatures from 256 to 538 degree C. Absorber of H2S needed to clean up gas streams from fuel processors that incorporate high-temperature steam reformers or hydrodesulfurizing units. Zeolites chosen as supporting materials because of their high porosity, rigidity, alumina content, and variety of both composition and form.

  3. ZEOLITES: EFFECTIVE WATER PURIFIERS

    EPA Science Inventory

    Zeolites are known for their adsorption, ion exchange and catalytic properties. Various natural zeolites are used as odor and moisture adsorbents and water softeners. Due to their acidic nature, synthetic zeolites are commonly employed as solid acid catalysts in petrochemical ind...

  4. Systems including catalysts in porous zeolite materials within a reactor for use in synthesizing hydrocarbons

    DOEpatents

    Rolllins, Harry W. (Idaho Falls, ID); Petkovic, Lucia M. (Idaho Falls, ID); Ginosar, Daniel M. (Idaho Falls, ID)

    2012-07-24

    Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

  5. Methods of using structures including catalytic materials disposed within porous zeolite materials to synthesize hydrocarbons

    DOEpatents

    Rollins, Harry W. (Idaho Falls, ID); Petkovic, Lucia M. (Idaho Falls, ID); Ginosar, Daniel M. (Idaho Falls, ID)

    2011-02-01

    Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

  6. Removal of metal cations from water using zeolites

    SciTech Connect

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

    1992-11-01

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

  7. Artificial neural network model in surface modification by EDM using tungsten–copper powder metallurgy sintered electrodes

    Microsoft Academic Search

    Promod Kumar Patowari; Partha Saha; P. K. Mishra

    2010-01-01

    Electro-discharge machining (EDM) is a widely accepted nontraditional machining process used mostly for machining materials\\u000a difficult to machine by conventional shearing process. Surface modification by powder metallurgy sintered tools is an uncommon\\u000a aspect of EDM. Of late, it is being explored by many researchers. In the present paper, attempts have been made to model the\\u000a surface modification phenomenon by EDM

  8. Zeolite Beta nanosized assemblies

    Microsoft Academic Search

    G. Majano; S. Mintova; O. Ovsitser; B. Mihailova; T. Bein

    2005-01-01

    Nanosized zeolite Beta assemblies are prepared by a steam assisted conversion (SAC) method from micron-sized porous amorphous silica grains soaked in clear solutions containing the alumina source and organic template. The zeolite Beta assemblies are built of closely packed uniform nanocrystals (100nm) and retain the size and morphological features of the primary silica grains. The crystallinity and the phase purity

  9. Electrode-modified zeolites: Electrode microstructures contained in and on a heterogeneous catalyst

    Microsoft Academic Search

    Debra R. Rolison; E. A. Hayes; R. J. Nowak; B. Stanley Pons; Martin Fleischmann

    1988-01-01

    In this work, zeolite-supported Pt(O) microstructures sized less than 10 nm are accessed as electrodes using dispersion electrolysis. Modification of an heterogeneous catalyst with ultramicroelectrodes permits exploration of electrode processes in an interphase dominated by the nature of the heterogeneous catalyst and at electrode sizes where bulk metallic properties may not apply. The systems described are Pt supported on zeolite

  10. Studies of anions sorption on natural zeolites.

    PubMed

    Barczyk, K; Mozgawa, W; Król, M

    2014-12-10

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

  11. Lithium modified zeolite synthesis for conversion of biodiesel-derived glycerol to polyglycerol

    NASA Astrophysics Data System (ADS)

    Ayoub, Muhammad; Abdullah, Ahmad Zuhairi; Inayat, Abrar

    2014-10-01

    Basic zeolite has received significant attention in the catalysis community. These zeolites modified with alkaline are the potential replacement for existing zeolite catalysts due to its unique features with added advantages. The present paper covers the preparation of lithium modified zeolite Y (Li-ZeY) and its activity for solvent free conversion of biodiesel-derived glycerol to polyglycerol via etherification process. The modified zeolite was well characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Nitrogen Adsorption. The SEM images showed that there was no change in morphology of modified zeolite structure after lithium modification. XRD patterns showed that the structure of zeolite was sustained after lithium modification. The surface properties of parent and modified zeolite was also observed N2 adsortion-desorption technique and found some changes in surface area and pore size. In addition, the basic strength of prepared materials was measured by Hammet indicators and found that basic strength of Li-ZeY was highly improved. This modified zeolite was found highly thermal stable and active heterogamous basic catalyst for conversion of solvent free glycerol to polyglycerol. This reaction was conducted at different temperatures and 260 °C was found most active temperature for this process for reaction time from 6 to 12 h over this basic catalyst in the absence of solvent.

  12. Regenerative Cu/La zeolite supported desulfurizing sorbents

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E. (inventor); Sharma, Pramod K. (inventor)

    1991-01-01

    Efficient, regenerable sorbents for removal of H2S from fluid hydrocarbons such as diesel fuel at moderate condition comprise a porous, high surface area aluminosilicate support, suitably a synthetic zeolite, and most preferably a zeolite having a free lattice opening of at least 6 Angstroms containing from 0.1 to 0.5 moles of copper ions, lanthanum ions or their mixtures. The sorbent removes sulfur from the hydrocarbon fuel in high efficiency and can be repetitively regenerated without loss of activity.

  13. Study of zeolite influence on analytical characteristics of urea biosensor based on ion-selective field-effect transistors

    NASA Astrophysics Data System (ADS)

    Shelyakina, Margaryta K.; Soldatkin, Oleksandr O.; Arkhypova, Valentyna M.; Kasap, Berna O.; Akata, Burcu; Dzyadevych, Sergei V.

    2014-03-01

    A possibility of the creation of potentiometric biosensor by adsorption of enzyme urease on zeolite was investigated. Several variants of zeolites (nano beta, calcinated nano beta, silicalite, and nano L) were chosen for experiments. The surface of pH-sensitive field-effect transistors was modified with particles of zeolites, and then the enzyme was adsorbed. As a control, we used the method of enzyme immobilization in glutaraldehyde vapour (without zeolites). It was shown that all used zeolites can serve as adsorbents (with different effectiveness). The biosensors obtained by urease adsorption on zeolites were characterized by good analytical parameters (signal reproducibility, linear range, detection limit and the minimal drift factor of a baseline). In this work, it was shown that modification of the surface of pH-sensitive field-effect transistors with zeolites can improve some characteristics of biosensors.

  14. Sorption effects in zeolite catalysis

    SciTech Connect

    Haag, W.O.

    1996-10-01

    Catalysis by zeolites and other microcrystalline materials is characterized by an unusually high degree of fundamental understanding. In acid catalysis, the active sites are part of the zeolite structure, not surface defects, and their nature and number can often be accurately determined. The dynamics of adsorption and desorption of reactant and product molecules, i.e. diffusion in zeolites, has also been extensively studied. Much less emphasis has been placed on a quantitative understanding of thermodynamic equilibrium sorption phenomena in zeolite catalyzed reactions. This talk will briefly discuss the principles and experimental data for hydrocarbon sorption in a variety of zeolites. It will then describe the application of these principles to a variety of zeolite catalyzed reactions. These include rate enhancements by non-acidic zeolites in thermal Diels-Alder reactions and paraffin cracking, the effect of carbon number and of zeolite structure on the observed activation energy of catalytic cracking, and the observation of very strong rate inhibition in ethylbenzene disproportionation.

  15. Catalytic combustion of propane and natural gas over Cu and Pd modified ZSM zeolite catalysts

    Microsoft Academic Search

    A. Kalantar Neyestanaki; N. Kumar; L.-E. Lindfors

    1995-01-01

    Copper-exchanged ZSM-5, ZSM-11 and ZSM-48 as well as Pd-ZSM-5 zeolite catalysts were prepared and tested for their light-off and conversion behaviour in complete oxidation of propane and natural gas. Metal modified ZSM zeolite catalysts were found to be superior to the Pd and Cu\\/alumina catalysts prepared for comparison. Cu-ZSM-5 (Cu, 1.3 wt.-%) appeared to be the most active of the

  16. Modification of algae with zinc, copper and silver ions for usage as natural composite for antibacterial applications.

    PubMed

    Mahltig, B; Soltmann, U; Haase, H

    2013-03-01

    Nanometer sized metal particles are used in many applications as antimicrobial materials. However in public discussion nanoparticular materials are a matter of concern due to potential health risks. Hence there is a certain demand for alternative antimicrobial acting materials. For this, the aim of this work is to realize an antimicrobial active material based on the release of metal ions from a natural depot. By this, the use of elemental metal particles or metal oxide particles in nanometer or micrometer scale is avoided. As natural depot four different algae materials (gained from Ascophyllum nodosum, Fucus vesicolosus, Spirulina platensis and Nannochloropsis) are used and loaded by bioabsorption with metal ions Ag(+), Cu(2+) and Zn(2+). The amount of metal bound by biosorption differs strongly in the range of 0.8 to 5.4 mg/g and depends on type of investigated algae material and type of metal ion. For most samples a smaller release of biosorbed Ag(+) and Cu(2+) is observed compared to a strong release of Zn(2+). The antibacterial activity of the prepared composites is investigated with Escherichia coli. Algae material without biosorbed metal has only a small effect on E. coli. Also by modification of algae with Zn(2+) only a small antibacterial property can be observed. Only with biosorption of Ag(+), the algae materials gain a strong bactericidal effect, even in case of a small amount of released silver ions. These silver modified algae materials can be used as highly effective bactericidal composites which may be used in future applications for the production of antimicrobial textiles, papers or polymer materials. PMID:25427514

  17. Hypothetical binodal zeolitic frameworks.

    PubMed

    Simperler, Alexandra; Foster, Martin D; Delgado Friedrichs, Olaf; Bell, Robert G; Almeida Paz, Filipe A; Klinowski, Jacek

    2005-06-01

    Hypothetical binodal zeolitic structures (structures containing two kinds of tetrahedral sites) were systematically enumerated using tiling theory and characterized by computational chemistry methods. Each of the 109 refineable topologies based on "simple tilings" was converted into a silica polymorph and its energy minimized using the GULP program with the Sanders-Catlow silica potential. Optimized structural parameters, framework energies relative to alpha-quartz and volumes accessible to sorption have been calculated. Eleven of the 30 known binodal topologies listed in the Atlas of Zeolite Framework Types were found, leaving 98 topologies that were unknown previously. The chemical feasibility of each structure as a zeolite was evaluated by means of a feasibility factor derived from the correlation between lattice energy and framework density. Structures are divided into 15 families, based on common structural features. Many "feasible" structures contain only small pores. Several very open structures were also enumerated, although they contain three-membered rings which are thermodynamically disfavoured and not found in conventional zeolites. We believe that such topologies may be realizable as framework materials, but with different elemental compositions to those normally associated with zeolites. PMID:15914891

  18. Zeolite-based catalysts for chemicals synthesis

    Microsoft Academic Search

    M. E. Davis

    1998-01-01

    A survey of the types of active sites and reaction chemistries possible with zeolite-based catalyst systems is presented. Several trends in zeolite catalysis for chemicals synthesis are enumerated and suggestions for work provided. Two emerging areas of zeolite catalysis for fine chemicals preparation, namely, extra-large pore zeolite catalysts and chiral zeolite catalysis, are described.

  19. Adsorption and degradation of enrofloxacin, a veterinary antibiotic on natural zeolite.

    PubMed

    Otker, Havva Merih; Akmehmet-Balcio?lu, I?il

    2005-07-15

    The adsorption of enrofloxacin, a veterinary antibiotic onto natural zeolite and further decontamination of zeolite was investigated in the present study. In the first part of the study, the effects of pH, temperature, and presence of ammonium ion on the adsorption process were examined and evaluated on the basis of Langmuir and Freundlich isotherms. Adsorption of enrofloxacin on natural zeolite was found to be highly pH dependent, exhibiting increases correspondent to decreases in pH. The positive value of enthalpy change showed the endothermic nature of adsorption processes. The presence of ammonium ion enhanced the adsorption of enrofloxacin. In the second part of the study, infrared (IR) spectroscopy, and scanning electron microscopy (SEM) were used for the determination of the modifications on the zeolite surfaces resulting from adsorption and ozone treatment. It was found that ozone at sufficient concentrations over specified time periods was able to decompose the enrofloxacin adsorbed on zeolite. PMID:15967281

  20. A reliable and reproducible method for the lipase assay in an AOT/isooctane reversed micellar system: modification of the copper-soap colorimetric method.

    PubMed

    Kwon, Chang Woo; Park, Kyung-Min; Choi, Seung Jun; Chang, Pahn-Shick

    2015-09-01

    The copper-soap method, which is based on the absorbance of a fatty acid-copper complex at 715 nm, is a widely used colorimetric assay to determine the lipase activity in reversed micellar system. However, the absorbance of the bis(2-ethylhexyl) sodium sulfosuccinate (AOT)-copper complex prevents the use of an AOT/isooctane reversed micellar system. An extraction step was added to the original procedure to remove AOT and eliminate interference from the AOT-copper complex. Among the solvents tested, acetonitrile was determined to be the most suitable because it allows for the generation of a reproducible calibration curve with oleic acid that is independent of the AOT concentrations. Based on the validation data, the modified method, which does not experience interference from the AOT-copper complex, could be a useful method with enhanced accuracy and reproducibility for the lipase assay. PMID:25842332

  1. Novel modified zeolites for energy-efficient hydrocarbon separations.

    SciTech Connect

    Arruebo, Manuel (University of Colorado, Boulder, CO); Dong, Junhang; Anderson, Thomas (Burns and McDonnell, Kansas City, MO); Gu, Xuehong; Gray, Gary (Goodyear Chemical Company, Akron, OH); Bennett, Ron (Goodyear Chemical Company, Akron, OH); Nenoff, Tina Maria; Kartin, Mutlu; Johnson, Kaylynn (Goodyear Chemical Company, Akron, OH); Falconer, John (University of Colorado, Boulder, CO); Noble, Richard (University of Colorado, Boulder, CO)

    2006-11-01

    We present synthesis, characterization and testing results of our applied research project, which focuses on the effects of surface and skeletal modification of zeolites for significant enhancements in current hydrocarbon (HC) separations. Zeolites are commonly used by the chemical and petroleum industries as catalysts and ion-exchangers. They have high potential for separations owing to their unique pore structures and adsorption properties and their thermal, mechanical and chemical properties. Because of zeolites separation properties, low cost, and robustness in industrial process, they are natural choice for use as industrial adsorbents. This is a multidisciplinary effort to research, design, develop, engineer, and test new and improved materials for the separation of branched vs. linear organic molecules found in commercially important HC streams via adsorption based separations. The focus of this project was the surface and framework modification of the commercially available zeolites, while tuning the adsorption properties and the selectivities of the bulk and membrane separations. In particular, we are interested with our partners at Goodyear Chemical, on how to apply the modified zeolites to feedstock isoprene purification. For the characterization and the property measurements of the new and improved materials powder X-ray diffraction (PXRD), Residual Gas Analyzer-Mass Spectroscopy (RGA-MS), Electron Microscopy (SEM/EDAX), temperature programmed desorption (TPD) and surface area techniques were utilized. In-situ carbonization of MFI zeolite membranes allowed for the maximum separation of isoprene from n-pentane, with a 4.1% enrichment of the binary stream with n-pentane. In four component streams, a modified MFI membrane had high selectivities for n-pentane and 1-3-pentadiene over isoprene but virtually no separation for the 2-methyl-2-butene/isoprene pair.

  2. Removal of BTEX from produced water using tailored zeolites

    SciTech Connect

    Cadena, F. [New Mexico State Univ., Las Cruces, NM (United States)

    1995-12-31

    The exchangeable cations in four natural zeolites (Bowie, CH, Winston and Tilden) were replaced with organic cations (quaternary amines). Two types of organic cations were used to create an organophilic environment suitable for adsorption of single-ring aromatics from water: small organic cations and long- alkyl chain cations. Both types of organic cations displace the natural exchangeable cations in the zeolite during the modification process. An organic layer covers the external surface of the zeolite after the natural inorganic cations are replaced by organic molecules. Two different pollutant adsorption mechanisms are observed in organozeolites. The first mechanism is prevalent when the zeolites are modified with small organic cations. The steric properties of adsorbed compounds are controlled by the intermolecular distance between the organic cations in the first mechanism. Benzene can be preferentially removed from solution over closely-related compounds (toluene and o-xylene) when the distance between organic cations is sufficient to allow this simple planar pollutant to enter into the intermolecular organic gaps. However, intermolecular distances that are significantly smaller than the benzene molecule prevent access to the adsorption sites. Organozeolites with long intermolecular gaps produce insufficient organic-organic interactions to hold the pollutants onto the solid-organic matrix. The selective adsorption produced by small organic cations is benzene >> toluene > xylene. The second mechanism is exhibited by zeolites modified with long-alkyl chains.

  3. Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures

    SciTech Connect

    Besser, J.M.; Ingersoll, C.G. [Geological Survey, Columbia, MO (United States); Leonard, E.N.; Mount, D.R. [Environmental Protection Agency, Duluth, MN (United States). Mid-Continent Ecology Div.

    1998-11-01

    Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. The authors investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by {ge}70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

  4. Quick Activation of Optimized Zeolites with Microwave Heating and Utilization of Zeolites for Reusable Desiccant

    Microsoft Academic Search

    Tatsuo Ohgushi; Mayumi Nagae

    2003-01-01

    Effectiveness of microwave heating in an activation treatment of zeolites was studied and utilization of zeolites for reusable desiccant was examined. X zeolite was chosen as a target material for its large adsorption capacity. Na-X zeolite easily caused a thermal runaway by microwave radiation of 500 W but Ca contained X zeolite merely reached ca. 573 K under the same

  5. Luminescent host–guest materials of electrostatically adsorbed Eu{sup 3+}(tta){sub 3}-tpyIL on zeolite L crystals

    SciTech Connect

    Li, Peng; Wang, Dongyue [Hebei Provincial Key Lab of Green Chemical Technology and High Efficient Energy Saving, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Liang, Dong [Tangshan Zhonghao chemical co. Ltd., Hebei 300130 (China); Zhang, Li; Zhang, Shuming [Hebei Provincial Key Lab of Green Chemical Technology and High Efficient Energy Saving, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Wang, Yige, E-mail: wangyige@hebut.edu.cn [Hebei Provincial Key Lab of Green Chemical Technology and High Efficient Energy Saving, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China)

    2014-07-01

    Graphical abstract: Luminescent host–guest materials exhibiting tunable emission colors by changing the excitation wavelength are obtained by surface modification of terbium(III) bipyridine-loaded zeolite L crystals with the ionic europium(III) complexes. - Highlights: • Luminescent ionic europium(III) complex was synthesized. • Outer surface of zeolite L was modified by electrostatic adsorption of the ionic complex. • Luminescent host–guest material with tunable emission color was obtained. - Abstract: The surface modification of zeolite L crystals with lanthanide complexes was achieved by electrostatic adsorption of ionic europium(III) complexes that are prepared by the reaction of tris(2-thenoyltrifluoroacetonate) europium(III) dehydrate with an organic salt containing terpyridine moieties on the negative charge-bearing surfaces of zeolite L crystals. Luminescent host–guest materials exhibiting tunable emission colors by changing the excitation wavelength are obtained by surface modification of terbium(III) bipyridine-loaded zeolite L crystals with the ionic europium(III) complexes.

  6. Ruthenium on Beta Zeolite in Cinnamaldehyde Hydrogenation

    Microsoft Academic Search

    M. Lashdaf; M. Tiitta; T. Venäläinen; H. Österholm; A. O. I. Krause

    2004-01-01

    The behaviour of ruthenium was studied in relation to the acidity of beta zeolite. The impregnation of beta zeolite with ruthenium chloride decreased the crystallite size of beta zeolite. The acidity of the beta zeolite influenced the particle size of ruthenium. The particle size of ruthenium increased with decreasing acidity. Even catalysts with large particle size of ruthenium were selective

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

    Microsoft Academic Search

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

    1981-01-01

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

  8. The modifications of copper work function by layer-by-layer deposition of [W(CN) 8] 4? – Co 2+ bimetallic nanolayers

    Microsoft Academic Search

    Tomasz Stawski; Janusz Szklarzewicz; Andrzej Kotarba; Pawe? Stelmachowski

    2009-01-01

    In the reaction of K4[W(CN)8]·2H2O and Co2+(aq) cations on the polycrystalline or monocrystalline [311] copper using layer-by-layer deposition, a thin film of the coordination polymer {[{Co(H2O)2(?-CN)4}2W]·4H2O}n was formed. The work function of copper and deposited on it bi-layers depended on a number of layers and the concentrations of the deposited precursors. At high complex concentrations work function reached the plateau

  9. Removal of radionuclides using zeolites

    SciTech Connect

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

    1996-10-01

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

  10. Multi-component lanthanide hybrids based on zeolite A/L and zeolite A/L-polymers for tunable luminescence.

    PubMed

    Chen, Lei; Yan, Bing

    2015-02-01

    Some multi-component hybrids based on zeolite L/A are prepared. Firstly, zeolite A/L is loaded with lanthanide complexes (Eu-DBM or Tb-AA (acetylacetone = AA, dibenzoylmethane = DBM)) into its channels. Secondly, 3-methacryloyloxypropyltrimethoxysilane (?-MPS) is used to covalently graft onto the surface of functionalized zeolite A/L (Si-[ZA/L?Eu-DBM(Tb-AA)]). Thirdly, lanthanide ions (Eu(3+)/Tb(3+)) are coordinated to the functionalized zeolite A/L and ligands (phen(1,10-phenanthroline) or bipy (2,2'-bipyridyl)) are introduced by a ship-in-bottle method. The inside-outside double modifications of ZA/L with lanthanide complexes afford the final hybrids and these are characterized by means of XRD, FT-IR, UV-vis DRS, SEM and luminescence spectroscopy, some of which display white or near-white light emission. Furthermore, selected above-mentioned hybrids are incorporated into PEMA/PMMA (poly ethyl methylacryate/poly methyl methacrylate) hosts to prepare luminescent polymer films. These results provide abundant data that these hybrid materials can be expected to have potential application in various practical fields. PMID:25411917

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

    Microsoft Academic Search

    M. A. Zanjanchi; E. Mohabbati

    2003-01-01

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

  12. Mechanism of Microwave Heating of Zeolite A

    Microsoft Academic Search

    Tatsuo Ohgushi; Sridhar Komarneni; Amar S. Bhalla

    2001-01-01

    The mechanism of microwave heating of A zeolite was studied by comparing the heating properties, cation distributions and dielectric properties of 3A, 4A and 5A zeolites. It was easy to heat hydrated 4A zeolite to a glowing (melting) temperature by microwave (2.45 GHz) radiation from room temperature but was difficult to heat the same zeolite with little hydration. When 4A

  13. Metal loading and reactivity of Zeolite

    E-print Network

    Sa?enz, Marc Gerard

    1988-01-01

    of experiments, increasing the amount of base increased the amount of cation deposited on the zeolite. In D'Aniello's experiments, increasing the amount of acid increased the amount of anion deposited on the alumina. However, alumina and zeolite Y... products with lower hydrogen to carbon atomic ratios. The zeolite based catalyst also exhibited a strong non-hydrogenative cracking function. The ability to control the ion exchange of zeolites by adjusting the pH of the exchanging slurry proved useful...

  14. Evaluation of operating characteristics for a chabazite zeolite system for treatment of process wastewater at Oak Ridge National Laboratory

    SciTech Connect

    Kent, T.E.; Perona, J.J.; Jennings, H.L.; Lucero, A.J.; Taylor, P.A.

    1998-02-01

    Laboratory and pilot-scale testing were performed for development and design of a chabazite zeolite ion-exchange system to replace existing treatment systems at the Process Waste Treatment Plant (PWTP) at Oak Ridge National Laboratory (ORNL). The process wastewater treatment systems at ORNL need upgrading to improve efficiency, reduce waste generation, and remove greater quantities of contaminants from the wastewater. Previous study indicated that replacement of the existing PWTP systems with an ion-exchange system using chabazite zeolite will satisfy these upgrade objectives. Pilot-scale testing of the zeolite system was performed using a commercially available ion-exchange system to evaluate physical operating characteristics and to validate smaller-scale column test results. Results of this test program indicate that (1) spent zeolite can be sluiced easily and completely from a commercially designed vessel, (2) clarification followed by granular anthracite prefilters is adequate pretreatment for the zeolite system, and (3) the length of the mass transfer zone was comparable with that obtained in smaller-scale column tests. Laboratory studies were performed to determine the loading capacity of the zeolite for selected heavy metals. These test results indicated fairly effective removal of silver, cadmium, copper, mercury, nickel, lead, and zinc from simple water solutions. Heavy-metals data collected during pilot-scale testing of actual wastewater indicated marginal removal of iron, copper, and zinc. Reduced effectiveness for other heavy metals during pilot testing can be attributed to the presence of interfering cations and the relatively short zeolite/wastewater contact time. Flocculating agents (polyelectrolytes) were tested for pretreatment of wastewater prior to the zeolite flow-through column system. Several commercially available polyelectrolytes were effective in flocculation and settling of suspended solids in process wastewater.

  15. Unconventional, highly selective CO2 adsorption in zeolite SSZ-13.

    PubMed

    Hudson, Matthew R; Queen, Wendy L; Mason, Jarad A; Fickel, Dustin W; Lobo, Raul F; Brown, Craig M

    2012-02-01

    Low-pressure adsorption of carbon dioxide and nitrogen was studied in both acidic and copper-exchanged forms of SSZ-13, a zeolite containing an 8-ring window. Under ideal conditions for industrial separations of CO(2) from N(2), the ideal adsorbed solution theory selectivity is >70 in each compound. For low gas coverage, the isosteric heat of adsorption for CO(2) was found to be 33.1 and 34.0 kJ/mol for Cu- and H-SSZ-13, respectively. From in situ neutron powder diffraction measurements, we ascribe the CO(2) over N(2) selectivity to differences in binding sites for the two gases, where the primary CO(2) binding site is located in the center of the 8-membered-ring pore window. This CO(2) binding mode, which has important implications for use of zeolites in separations, has not been observed before and is rationalized and discussed relative to the high selectivity for CO(2) over N(2) in SSZ-13 and other zeolites containing 8-ring windows. PMID:22235866

  16. Influence of starting zeolite on synthesis of RUT type zeolite by interzeolite conversion method

    NASA Astrophysics Data System (ADS)

    Itakura, Masaya; Ota, Kai; Shibata, Shohei; Inoue, Takayuki; Ide, Yusuke; Sadakane, Masahiro; Sano, Tsuneji

    2011-01-01

    In this study, hydrothermal conversions of *BEA and FAU type zeolites using various structure-directing agents were carried out. Highly crystalline and pure RUT type zeolites were obtained from both zeolites in the presence of tetramethylammonium hydroxide. There were no major differences between the characteristics of the RUT type zeolites obtained from the two starting zeolites. However, the Si/Al ratio and the crystallization rate of the RUT type zeolites were strongly dependent on both the framework structure and the Si/Al ratio of the starting zeolite. That is, the crystallization rate of the RUT type zeolite from the *BEA type zeolite did not depend on the Si/Al ratio of the starting *BEA type zeolite, whereas the crystallization rate of the RUT type zeolite from the FAU type zeolite was dependent on the Si/Al ratio of the starting FAU type zeolite. This suggests that the chemical structure and the concentration of locally ordered aluminosilicate species produced by the decomposition/dissolution of the starting zeolite can be altered by changing the framework structure of the zeolite.

  17. Gas-phase adsorption in dealuminated natural clinoptilolite and liquid-phase adsorption in commercial DAY zeolite and modified ammonium Y zeolite

    NASA Astrophysics Data System (ADS)

    Costa Hernandez, Alba Nydia

    The adsorption of Carbon Dioxide (CO2) is a very important tool for the material characterization. On the other hand, in separation and recovery technology, the adsorption of the CO2 is important to reduce the concentration of this gas considered as one of the greenhouse gases. Natural zeolites, particularly clinoptilolite, are widely applied to eliminate some pollutants from the environment. One of the goals of this research is to study the structure, composition and morphology of one natural clinoptilolite dealuminated with ammonium hexafluorosilicate (AHFi) and with orthophosphoric acid (H3PO4). Each modified sample was characterized using X-ray Diffraction (XRD), Carbon Dioxide adsorption at 0° C, Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDAX). In addition, the surface chemistry of the modified clinoptilolites was analyzed with Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS). The adsorption measurements were also used to study of the interaction of CO2 molecule within the adsorption space of these modified clinoptilolites. It was concluded that one of the modified clinoptilolites, (CSW-HFSi-0.1M), showed a great quality as adsorbent and as catalytic comparable to commercial synthetic zeolites. As far as we know, the modification of clinoptilolite with HFSi to improve their adsorption properties had not been previously attempted. In the second part of this dissertation, the dynamic adsorption of three isomers of nitrophenols using as adsorbent a commercial DAY zeolite was investigated. Also, the dynamic adsorption of methanol in a less hydrophobic zeolite, Ammonium Y Zeolite was investigated. The obtained breakthrough curves showed that the commercial DAY zeolite could be a suitable adsorbent to the liquid-phase adsorption of the phenolic compounds. Notwithstanding the modified ammonium Y zeolite had a low Si/Al ratio (less hydrophobic) than commercial DAY zeolite; this modified zeolite was useful for the dynamic adsorption of polar compound such as methanol. The obtained results were consistent with those reported in other studies related with the use of zeolites in the removal of organic compounds from the liquid phase.

  18. Inhibition of copper corrosion by self-assembled films of new Schiff bases and their modification with alkanethiols in aqueous medium

    NASA Astrophysics Data System (ADS)

    Ehteshamzade, M.; Shahrabi, T.; Hosseini, M. G.

    2006-02-01

    The inhibitive action of self-assembled films derived from two ligands Schiff bases, including N, N'-ethylen-bis (salicylidenimine) and N, N'- ortho-phenylen-bis (salicylidenimine) on copper surface has been studied by electrochemical techniques in chloride and acidic solutions. It was found that when the concentration of the inhibitors was increased the inhibition efficiency was increased, too. The results of the electrochemical studies have illustrated that the inhibition efficiency of S- o-ph-S is higher than S-E-S. Both the Schiff bases obeyed the Langmuir isotherm and thermodynamics calculations revealed that S- o-ph-S had larger adsorption constant and more negative free energy of adsorption with respect to S-E-S. When the films were modified by propanethiol and 1-dodecanethiol, the corrosion resistance of mixed films was significantly increased.

  19. Suspending Zeolite Particles In Tanks

    SciTech Connect

    Poirier, M.R.

    1999-01-19

    The Savannah River Site (SRS) is in the process of removing waste (sludge and salt cake) from million gallon waste tanks. The current practice for removing waste from the tanks is adding water, agitating the tanks with long shaft vertical centrifugal pumps, and pumping the sludge/salt solution from the tank to downstream treatment processes. This practice has left sludge heels ({tilde} 30,000 gallons) in the bottom of the tanks. SRS is evaluating shrouded axial impeller mixers for removing the sludge heels in the waste tanks. The authors conducted a test program to determine mixer requirements for suspending sludge heels using the shrouded axial impeller mixers. The tests were performed with zeolite in scaled tanks which have diameters of 1.5, 6.0, and 18.75 feet. The mixer speeds required to suspend zeolite particles were measured at each scale. The data were analyzed with various scaling methods to compare their ability to describe the suspension of insoluble solids with the mixers and to apply the data to a full-scale waste tank. The impact of changes in particle properties and operating parameters was also evaluated. The conclusions of the work are: Scaling of the suspension of fast settling zeolite particles was best described by the constant power per unit volume method. Increasing the zeolite particle concentration increased the required mixer power needed to suspend the particles. Decreasing the zeolite particle size from 0.7 mm ? 0.3 mm decreased the required mixer power needed to suspend the particles. Increasing the number of mixers in the tank decreased the required mixer power needed to suspend the particles. A velocity of 1.6 ft/sec two inches above the tank bottom is needed to suspend zeolite particles.

  20. Spectroscopic signatures of nitrogen-substituted zeolites.

    PubMed

    Hammond, Karl D; Dogan, Fulya; Tompsett, Geoffrey A; Agarwal, Vishal; Conner, W Curtis; Grey, Clare P; Auerbach, Scott M

    2008-11-12

    Nanoporous acid catalysts such as zeolites form the backbone of catalytic technologies for refining petroleum. With the promise of a biomass economy, new catalyst systems will have to be discovered, making shape-selective base catalysts especially important because of the high oxygen content in biomass-derived feedstocks. Strongly basic zeolites are attractive candidates, but such materials are notoriously difficult to make due to the strong inherent acidity of aluminosilicates. Several research groups have endeavored to produce strongly basic zeolites by treating zeolites with amines, but to date there is no compelling evidence that nitrogen is incorporated into zeolite frameworks. In this communication, we detail synthesis, NMR spectroscopy, and quantum mechanical calculations showing that nitrogen adds onto both surface and interior sites while preserving the framework structure of zeolites. This finding is crucial for the rational design of new biomass-refinement catalysts, allowing 50 years of zeolite science to be brought to bear on the catalytic synthesis of biofuels. PMID:18855470

  1. Enhanced selectivity of zeolites by controlled carbon deposition

    DOEpatents

    Nenoff, Tina M.; Thoma, Steven G.; Kartin, Mutlu

    2006-05-09

    A method for carbonizing a zeolite comprises depositing a carbon coating on the zeolite pores by flowing an inert carrier gas stream containing isoprene through a regenerated zeolite at elevated temperature. The carbonized zeolite is useful for the separation of light hydrocarbon mixtures due to size exclusion and the differential adsorption properties of the carbonized zeolite.

  2. Modifications on the hydrogen bond network by mutations of Escherichia coli copper efflux oxidase affect the process of proton transfer to dioxygen leading to alterations of enzymatic activities

    SciTech Connect

    Kajikawa, Takao; Kataoka, Kunishige [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)] [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan); Sakurai, Takeshi, E-mail: tsakurai@se.kanazawa-u.ac.jp [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)] [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)

    2012-05-25

    Highlights: Black-Right-Pointing-Pointer Proton transfer pathway to dioxygen in CueO was identified. Black-Right-Pointing-Pointer Glu506 is the key amino acid to transport proton. Black-Right-Pointing-Pointer The Ala mutation at Glu506 formed a compensatory proton transfer pathway. Black-Right-Pointing-Pointer The Ile mutation at Glu506 shut down the hydrogen bond network. -- Abstract: CueO has a branched hydrogen bond network leading from the exterior of the protein molecule to the trinuclear copper center. This network transports protons in the four-electron reduction of dioxygen. We replaced the acidic Glu506 and Asp507 residues with the charged and uncharged amino acid residues. Peculiar changes in the enzyme activity of the mutants relative to the native enzyme indicate that an acidic amino acid residue at position 506 is essential for effective proton transport. The Ala mutation resulted in the formation of a compensatory hydrogen bond network with one or two extra water molecules. On the other hand, the Ile mutation resulted in the complete shutdown of the hydrogen bond network leading to loss of enzymatic activities of CueO. In contrast, the hydrogen bond network without the proton transport function was constructed by the Gln mutation. These results exerted on the hydrogen bond network in CueO are discussed in comparison with proton transfers in cytochrome oxidase.

  3. Hydrodewaxing with mixed zeolite catalysts

    SciTech Connect

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

    1986-03-11

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

  4. Zeolite Mineralogy and Cappadocian Erionite

    Microsoft Academic Search

    A. Umran Dogan

    2003-01-01

    The discovery some 30 years ago that erionite, a fibrous zeolite mineral, induced mesotheliomas in those living in certain villages in Cappadocia engendered a vast amount of both geological\\/mineralogical and clinical\\/epidemiological work. Studies initially concentrated on three villages where the incidence of this normally rare tumour correlated with the presence of erionite, and has extended to some new villages also

  5. Hydrogen Selective Exfoliated Zeolite Membranes

    SciTech Connect

    Tsapatsis, Michael; Daoutidis, Prodromos; Elyassi, Bahman; Lima, Fernando; Iyer, Aparna; Agrawal, Kumar; Sabnis, Sanket

    2014-09-30

    The objective of this project was to develop and evaluate an innovative membrane technology at process conditions that would be representative of Integrated Gasification Combined Cycle (IGCC) advanced power generation with pre-combustion capture of carbon dioxide (CO2). This research focused on hydrogen (H2)-selective zeolite membranes that could be utilized to separate conditioned syngas into H2-rich and CO2-rich components. Both experiments and process design and optimization calculations were performed to evaluate the concept of ultra-thin membranes made from zeolites nanosheets. In this work, efforts in the laboratory were made to tackle two fundamental challenges in application of zeolite membranes in harsh industrial environments, namely, membrane thickness and membrane stability. Conventional zeolite membranes have thicknesses in the micron range, limiting their performance. In this research, we developed a method for fabrication of ultimately thin zeolite membranes based on zeolite nanosheets. A range of layered zeolites (MWW, RWR, NSI structure types) suitable for hydrogen separation was successfully exfoliated to their constituent nanosheets. Further, membranes were made from one of these zeolites, MWW, to demonstrate the potential of this group of materials. Moreover, long-term steam stability of these zeolites (up to 6 months) was investigated in high concentrations of steam (35 mol% and 95 mole%), high pressure (10 barg), and high temperatures (350 oC and 600 oC) relevant to conditions of water-gas-shift and steam methane reforming reactions. It was found that certain nanosheets are stable, and that stability depends on the concentration of structural defects. Additionally, models that represent a water-gas-shift (WGS) membrane reactor equipped with the zeolite membrane were developed for systems studies. These studies had the aim of analyzing the effect of the membrane reactor integration into IGCC plants in terms of performance and economic aspects of the plants. Specifically, simulation and design optimization studies were performed using the developed stand-alone membrane reactor models to identify the membrane selectivity and permeance characteristics necessary to achieve desired targets of CO2 capture and H2 recovery, as well as guide the selection of the optimal reactor design that minimizes the membrane cost as a function of its surface area required. The isothermal membrane reactor model was also integrated into IGCC system models using both the MATLAB and Aspen software platforms and techno-economic analyses of the integrated plants have been carried out to evaluate the feasibility of replacing current technologies for pre-combustion capture by the proposed novel approach in terms of satisfying stream constraints and achieving the DOE target goal of 90% CO2 capture. The results of the performed analyses based on present value of annuity calculations showed break even costs for the membrane reactor within the feasible range for membrane fabrication. However, the predicted membrane performance used in these simulations exceeded the performance achieved experimentally. Therefore, further work is required to improve membrane performance.

  6. Resonant diffusion of normal alkanes in zeolites: Effect of the zeolite structure and alkane molecule vibrations

    E-print Network

    Tsekov, R

    2015-01-01

    Diffusion of normal alkanes in one-dimensional zeolites is theoretically studied on the basis of the stochastic equation formalism. The calculated diffusion coefficient accounts for the vibrations of the diffusing molecule and zeolite framework, molecule-zeolite interaction, and specific structure of the zeolite. It is shown that when the interaction potential is predominantly determined by the zeolite pore structure, the diffusion coefficient varies periodically with the number of carbon atoms of the alkane molecule, a phenomenon called resonant diffusion. A criterion for observable resonance is obtained from the balance between the interaction potentials of the molecule due to the atomic and pore structures of the zeolite. It shows that the diffusion is not resonant in zeolites without pore structure, such as ZSM-12. Moreover, even in zeolites with developed pore structure no resonant dependence of the diffusion constant can be detected if the pore structure energy barriers are not at least three times high...

  7. Spin probes of chemistry in zeolites

    SciTech Connect

    Werst, D.W.; Trifunac, A.D.

    1997-09-01

    Electron spin resonance (EPR) studies in zeolites are reviewed in which radiolysis was used to ionize the zeolite lattice, create reactive intermediates, spin label reaction products and to provide a window onto chemistry and transport of adsorbates and matrix control of chemistry. The review examines reactions of radical cations and the influence of the geometry constraints inside the zeolite, explores how zeolite model systems can be used to learn about energy and charge transfer in solids and illustrates the use of radiolysis and EPR for in situ spectroscopic studies of solid-acid catalysis. The various spin probes created inside the zeolite pores report on properties of the zeolites as well as shed light on radiolytic processes.

  8. Surfactant-modified zeolite as a slow release fertilizer for phosphorus.

    PubMed

    Bansiwal, Amit Kumar; Rayalu, Sadhana Suresh; Labhasetwar, Nitin Kumar; Juwarkar, Asha Ashok; Devotta, Sukumar

    2006-06-28

    The feasibility of using surfactant-modified zeolite (SMZ) as a carrier for fertilizer and for slow release of phosphorus (P) was investigated. Zeolite-A was modified by using hexadecyltrimethylammonium bromide, a cationic surfactant, to modify its surface to increase its capacity to retain anion, namely, phosphate (PO4(3-)). SMZ was thoroughly characterized using X-ray diffraction, Fourier transform infrared, and scanning electron microscopy to study the effect of surfactant modification. Zeolite-A and SMZ were then subjected to P loading by treating them with fertilizer (KH2PO4). It was observed that the P loading on SMZ increased by a factor of 4.9 as compared to the unmodified zeolite-A. A comparative study of the release of P from fertilizer-loaded unmodified zeolite-A and SMZ and from solid KH2PO4 was performed using the constant flow percolation reactor. The results show that the P supply from fertilizer-loaded SMZ was available even after 1080 h of continuous percolation, whereas P from KH2PO4 was exhausted within 264 h. The results indicate that SMZ is a good sorbent for PO4(3-), and a slow release of P was achievable. These properties suggest that SMZ has a great potential as the fertilizer carrier for slow release of P. PMID:16787027

  9. Zeolite synthesis in hydrated silicate ionic liquids.

    PubMed

    van Tendeloo, Leen; Haouas, Mohamed; Martens, Johan A; Kirschhock, C E A; Breynaert, Eric; Taulelle, Francis

    2015-01-01

    Hydrated alkali silicate ionic liquids (HSIL) were prepared by hydrolysis of tetraethoxysilane (TEOS) in alkali hydroxide-water mixtures, inducing coacervation and phase separation. The resulting optically clear, homogenous silicate ionic liquid offers exceptional potential for monitoring zeolite crystallisation. This enhanced synthesis route provides access to analysis of speciation, mechanistic details of zeolite formation, and brings organic-template-free zeolite synthesis by design within reach. PMID:25886652

  10. Attempts to Synthesize Zeolitic Composites from Stellerite

    Microsoft Academic Search

    Ming Bo Yue; Li Huang; Xin Dong; Jia Hui Xu; Jian Hua Zhu

    2007-01-01

    A feasible method to synthesize NaA and NaY zeolite from stellerite, the very cheap raw material found in China, was reported in this article to reduce the cost of zeolite synthesis for the first time. After stellerite is calcined above 973 K with sodium carbonate, this natural zeolite can be slowly dissolved in alkali solution and partly forms the gels, then

  11. Molecular simulations and experimental studies of zeolites

    Microsoft Academic Search

    Eric C. Moloy

    2004-01-01

    Zeolites are microporous aluminosilicate tetrahedral framework materials that have symmetric cages and channels with open-diameters between 0.2 and 2.0 nm. Zeolites are used extensively in the petrochemical industries for both their microporosity and their catalytic properties. The role of water is paramount to the formation, structure, and stability of these materials. Zeolites frequently have extra-framework cations, and as a result,

  12. Increased thermal conductivity monolithic zeolite structures

    DOEpatents

    Klett, James (Knoxville, TN); Klett, Lynn (Knoxville, TN); Kaufman, Jonathan (Leonardtown, MD)

    2008-11-25

    A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

  13. Treating Coalbed Natural Gas Produced Water for Beneficial Use By MFI Zeolite Membranes

    SciTech Connect

    Robert Lee; Liangxiong Li

    2008-03-31

    Desalination of brines produced from oil and gas fields is an attractive option for providing potable water in arid regions. Recent field-testing of subsurface sequestration of carbon dioxide for climate management purposes provides new motivation for optimizing efficacy of oilfield brine desalination: as subsurface reservoirs become used for storing CO{sub 2}, the displaced brines must be managed somehow. However, oilfield brine desalination is not economical at this time because of high costs of synthesizing membranes and the need for sophisticated pretreatments to reduce initial high TDS and to prevent serious fouling of membranes. In addition to these barriers, oil/gas field brines typically contain high concentrations of multivalent counter cations (eg. Ca{sup 2+} and SO{sub 4}{sup 2-}) that can reduce efficacy of reverse osmosis (RO). Development of inorganic membranes with typical characteristics of high strength and stability provide a valuable option to clean produced water for beneficial uses. Zeolite membranes have a well-defined subnanometer pore structure and extreme chemical and mechanical stability, thus showing promising applicability in produced water purification. For example, the MFI-type zeolite membranes with uniform pore size of {approx}0.56 nm can separate ions from aqueous solution through a mechanism of size exclusion and electrostatic repulsion (Donnan exclusion). Such a combination allows zeolite membranes to be unique in separation of both organics and electrolytes from aqueous solutions by a reverse osmosis process, which is of great interest for difficult separations, such as oil-containing produced water purification. The objectives of the project 'Treating Coalbed Natural Gas Produced Water for Beneficial Use by MFI Zeolite Membranes' are: (1) to conduct extensive fundamental investigations and understand the mechanism of the RO process on zeolite membranes and factors determining the membrane performance, (2) to improve the membranes and optimize operating conditions to enhance water flux and ion rejection, and (3) to perform long-term RO operation on tubular membranes to study membrane stability and to collect experimental data necessary for reliable evaluations of technical and economic feasibilities. Our completed research has resulted in deep understanding of the ion and organic separation mechanism by zeolite membranes. A two-step hydrothermal crystallization process resulted in a highly efficient membrane with good reproducibility. The zeolite membranes synthesized therein has an overall surface area of {approx}0.3 m{sup 2}. Multichannel vessels were designed and machined for holding the tubular zeolite membrane for water purification. A zeolite membrane RO demonstration with zeolite membranes fabricated on commercial alpha-alumina support was established in the laboratory. Good test results were obtained for both actual produced water samples and simulated samples. An overall 96.9% ion rejection and 2.23 kg/m{sup 2}.h water flux was achieved in the demonstration. In addition, a post-synthesis modification method using Al{sup 3+}-oligomers was developed for repairing the undesirable nano-scale intercrystalline pores. Considerable enhancement in ion rejection was achieved. This new method of zeolite membrane modification is particularly useful for enhancing the efficiency of ion separation from aqueous solutions because the modification does not need high temperature operation and may be carried out online during the RO operation. A long-term separation test for actual CBM produced water has indicated that the zeolite membranes show excellent ion separation and extraordinary stability at high pressure and produced water environment.

  14. Widening Synthesis Bottlenecks: Realization of Ultrafast and Continuous-Flow Synthesis of High-Silica Zeolite SSZ-13 for NOx Removal.

    PubMed

    Liu, Zhendong; Wakihara, Toru; Oshima, Kazunori; Nishioka, Daisuke; Hotta, Yuusuke; Elangovan, Shanmugam P; Yanaba, Yutaka; Yoshikawa, Takeshi; Chaikittisilp, Watcharop; Matsuo, Takeshi; Takewaki, Takahiko; Okubo, Tatsuya

    2015-05-01

    Characteristics of zeolite formation, such as being kinetically slow and thermodynamically metastable, are the main bottlenecks that obstruct a fast zeolite synthesis. We present an ultrafast route, the first of its kind, to synthesize high-silica zeolite SSZ-13 in 10?min, instead of the several days usually required. Fast heating in a tubular reactor helps avoid thermal lag, and the synergistic effect of addition of a SSZ-13 seed, choice of the proper aluminum source, and employment of high temperature prompted the crystallization. Thanks to the ultra-short period of synthesis, we established a continuous-flow preparation of SSZ-13. The fast-synthesized SSZ-13, after copper-ion exchange, exhibits outstanding performance in the ammonia selective catalytic reduction (NH3 -SCR) of nitrogen oxides (NOx ), showing it to be a superior catalyst for NOx removal. Our results indicate that the formation of high-silica zeolites can be extremely fast if bottlenecks are effectively widened. PMID:25801140

  15. Optimization of copper wire bonding on Al-Cu metallization

    Microsoft Academic Search

    Luu T. Nguyen; David McDonald; Anselm R. Danker; Peter Ng

    1995-01-01

    This paper reports the successful implementation of copper wire ball bonding for selected TO-220 devices on a high volume commercial scale. Since August 1992, copper wire bonding has been used in production at National Semiconductor Corp. The development of copper wire ball bonding involves a three-prong approach: optimum pad metal composition, modifications to the wire bonder and optimization of the

  16. Nanocrystalline Zeolites: Synthesis, Mechanism, and Applications

    NASA Astrophysics Data System (ADS)

    Severance, Michael Andrew

    Nanocrystalline zeolite particles are becoming an important material in many technical applications (e.g. zeolite membranes). Synthetic methods that minimize the zeolite crystal diameter, while providing a narrow particle size distribution, are of primary importance in these technical applications. However, there are several limitations to currently existing synthetic routes aimed at producing nanozeolites and zeolite membrane devices. For example, zeolite growth in these contexts typically requires days to weeks at high temperature to crystallize. Despite excellent performance of zeolite membranes in several separation applications, the long synthesis times required undermine any practical application of these technologies. This work focuses on chemical manipulation of zeolite nucleation processes in sol gel systems in effort to address such limitations. The primary findings indicate that careful control of the nucleation stage of a clear zeolite synthesis (optically transparent sol gel) allow the formation of zeolite Y nanocrystals less than 50 nm in diameter with a polydispersity index less than 0.2. Furthermore, chemical perturbations made during the nucleation stage of zeolite Y hydrogel synthesis is shown to accelerate crystal growth by a factor of 3-4, depending on the specific sol gel chemistry. These findings are applied to the nanocrystal seeding and rapid hydrothermal growth of zeolite Y membranes on inexpensive polymeric supports. A novel synthetic method is developed to this end. Also, the chemical and physical properties of monodisperse nanocrystalline zeolite Y synthesized herein are explored by electrochemical impedance spectroscopy. It is found that the particle interface plays an important role in the ionic conductivity of nanocrystalline zeolites in contrast to their larger zeolite counterparts in analogy to other ceramic and metal oxide ion conductors. Finally, the possibility to produce novel organic and inorganic composite systems through zeolite host-guest chemistry is explored. A nanozeolite-silver nanoparticle host-guest system is synthesized and a mechanism describing its evolution is developed. Also, the photochemistry of a colloidal nanozeolite-organic dye host-guest system is explored with ultrafast transient UV-Vis absorption spectroscopy. This allows some of the fastest chemical events to be probed within the host-guest system.

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

    PubMed

    Iwamoto, Masakazu; Hoshino, Yasuyuki

    1996-11-20

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

  18. Metal/zeolite catalysts of methane dehydroaromatization

    NASA Astrophysics Data System (ADS)

    Mamonov, N. A.; Fadeeva, E. V.; Grigoriev, D. A.; Mikhailov, M. N.; Kustov, Leonid M.; Alkhimov, S. A.

    2013-06-01

    Results of studying methane dehydroaromatization over metal/zeolite catalysts have been reviewed. Special attention has focused on molybdenum catalysts based on HZSM-5 zeolites. The effect of catalyst synthesis and reaction conditions on the catalytic properties of the systems has been scrutinized. Information on the mechanism of the process and the nature of active sites has been reported. The bibliography includes 137 references.

  19. Selective anisotropic growth of zeolite crystals

    E-print Network

    Desai, Tasha April

    2013-02-22

    . To achieve this end we are attempting to grow zeolite particles in the confined water spaces formed in water/surfactant systems, using these "nanoreactors" to modulate zeolite growth. Our work to date has focused on the synthesis of two-dimensional (5x100x...

  20. The flexibility of zeolites for Hydrogen storage

    NASA Astrophysics Data System (ADS)

    Sartbaeva, Asel; Wells, Stephen Anthony; Edwards, Peter P.

    2008-03-01

    The flexibility window is a newly discovered theoretical measure which can provide a valuable selection criterion when evaluating hypothetical zeolite framework structures as potential synthetic targets. Today synthetic zeolites are the most important catalysts in petrochemical refineries. There have been considerable efforts to synthesize new zeolites with specific pore geometries, to add to the 167 available at present. Millions of hypothetical structures have been generated on the basis of energy minimization, and there is an ongoing search for criteria capable of predicting new zeolite structures. The flexibility window appears to be a property of existing zeolite frameworks not shared by many hypothetical structures. It provides a valuable selection criterion when evaluating hypothetical zeolite framework structures as potential synthetic targets. We are investigating the use of zeolites as hydrogen storage materials, as small molecules such as molecular hydrogen and ammonia can be easily absorbed into a flexible framework of zeolites. An exiting possibility is the use of framework flexibility to control hydrogen uptake, storage and release. This would allow a safe use of hydrogen for fuel cells.

  1. Cracking of naphtha range alkanes and naphthenes over zeolites

    Microsoft Academic Search

    Hayim Abrevaya

    2007-01-01

    Naphtha range alkanes and naphthenes can be activated over H-form of zeolites, which provide low temperature cracking pathways that are otherwise unavailable during conventional steam cracking. A range of zeolitic catalysts were tested for cracking naphtha. Due to their relatively larger kinetic diameter, isoalkanes and naphthenes exhibited lower reactivity than linear alkanes over 8-MR zeolites. 12-MR zeolites favored bimolecular hydride

  2. Thermal degradation of epoxy\\/natural zeolite composites

    Microsoft Academic Search

    Jae-Young Lee; Mi-Ja Shim; Sang-Wook Kim

    2001-01-01

    The characteristics of thermal degradation of epoxy system filled with natural zeolite were studied by thermogravimetry analysis (TGA). All the epoxy composites were degraded in one stage regardless of the zeolite content. In the Freeman & Carroll equation, the activation energy at 20 phr of zeolite was lower than that at any other content of zeolite and these values decreased

  3. Evaluation of zeolite-sand mixtures as reactive materials protecting groundwater at waste disposal sites.

    PubMed

    Joanna, Fronczyk; Kazimierz, Garbulewski

    2013-09-01

    To recognize properties of a mixture of Vistula sand (medium sand acc. to USCS) with Slovak zeolite as reactive materials suitable for permeable reactive barriers proposed for protection of groundwater environment in vicinity of old landfills comprehensive laboratory investigations were performed. The present study investigates the removal of contaminants specific for landfill leachates onto zeolite-sand mixtures containing 20%, 50% and 80% of zeolite (ZS20, ZS50 and ZS80). Taking into account the results of batch tests it was concluded that the Langmuir isotherm best fitted the data. It was observed that the presence of ammonium, calcium and magnesium decreases the removal efficiency of copper by 32%. Column tests of contaminant migration through the attenuation zone of the reactive materials were interpreted using the software package CXTFIT, which solves a one-dimensional advection-dispersion equation. Column test results also indicate the strong influence of the presence of interfering substances on copper immobilisation; dynamic sorption capacities decrees twofold. Throughout the landfill leachate flow through ZS80 sample, a constant reduction of NH4+ (at 100%), K+ (at 93%) and Fe(total) (at an average of 86%) were observed. There was no reduction in chemical oxygen demand and biochemical oxygen demand. PMID:24520718

  4. Zeolitic materials with hierarchical porous structures.

    PubMed

    Lopez-Orozco, Sofia; Inayat, Amer; Schwab, Andreas; Selvam, Thangaraj; Schwieger, Wilhelm

    2011-06-17

    During the past several years, different kinds of hierarchical structured zeolitic materials have been synthesized due to their highly attractive properties, such as superior mass/heat transfer characteristics, lower restriction of the diffusion of reactants in the mesopores, and low pressure drop. Our contribution provides general information regarding types and preparation methods of hierarchical zeolitic materials and their relative advantages and disadvantages. Thereafter, recent advances in the preparation and characterization of hierarchical zeolitic structures within the crystallites by post-synthetic treatment methods, such as dealumination or desilication; and structured devices by in situ and ex situ zeolite coatings on open-cellular ceramic foams as (non-reactive as well as reactive) supports are highlighted. Specific advantages of using hierarchical zeolitic catalysts/structures in selected catalytic reactions, such as benzene to phenol (BTOP) and methanol to olefins (MTO) are presented. PMID:21495091

  5. Dispersion strengthened copper

    DOEpatents

    Sheinberg, Haskell (Los Alamos, NM); Meek, Thomas T. (Knoxville, TN); Blake, Rodger D. (Santa Fe, NM)

    1990-01-01

    A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

  6. Dispersion strengthened copper

    DOEpatents

    Sheinberg, Haskell (Los Alamos, NM); Meek, Thomas T. (Knoxville, TN); Blake, Rodger D. (Santa Fe, NM)

    1989-01-01

    A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

  7. The effect of pore dimension of zeolites on the separation of gas mixtures

    NASA Astrophysics Data System (ADS)

    Jee, Sang Eun

    We examined the effect of the pore dimension of zeolites on the separation of gas mixtures using atomistic simulation methods. We studied two categories of the zeolites with small pores: pore modified silicalite for H2/CH4 separation and small pore silica zeolites for CO2/CH4 separation. The effect of pore modification of silicalite on the H2/CH4 separation was examined. Under some degrees of surface modification, the CH4 flux was reduced much more than the H2 flux, resulting in high ideal selectivities. The use of small pore zeolites for CO2/CH4 separations was studied. In DDR, we showed that CO2 diffusion rates are only weakly affected by the presence of CH4, even though the latter molecules diffuse very slowly. Consequently, therefore, the permeance of CO 2 in the equimolar mixtures is similar to the permeance for pure CO 2, while the CH4 permeance in the mixture is greatly reduced relatively to the pure component permeance. The calculated CO2/CH 4 separation selectivities are higher than 100 for a wide range of feed pressure, indicating excellent separation capabilities of DDR based membranes. Inspired by the observation in DDR we also examined the separation capabilities of 10 additional pure silica small pore zeolites for CO2/CH 4 separations. From these considerations, we predict that SAS, MTF and RWR will exhibit high separation selectivities because of their very high adsorption selectivities for CO2 over CH4. CHA and IHW, which have similar pore structures to DDR, showed comparable separation selectivities to DDR because of large differences in the diffusion rates of CO2 and CH4.

  8. Dye house wastewater treatment through advanced oxidation process using Cu-exchanged Y zeolite: A heterogeneous catalytic approach

    Microsoft Academic Search

    Nishtar Nishad Fathima; Rathinam Aravindhan; Jonnalagadda Raghava Rao; Balachandran Unni Nair

    2008-01-01

    Catalytic wet hydrogen peroxide oxidation of an anionic dye has been explored in this study. Copper(II) complex of NN?–ethylene bis(salicylidene-aminato) (salenH2) has been encapsulated in super cages of zeolite-Y by flexible ligand method. The catalyst has been characterized by Fourier transforms infra red spectroscopy, X-ray powder diffractograms, Thermo-gravimetric and differential thermal analysis and nitrogen adsorption studies. The effects of various

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

    Microsoft Academic Search

    Thomas Bein; Peter A. Jacobs

    1983-01-01

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

  10. Photoinduced electron transfer reactions in zeolite cages

    SciTech Connect

    Dutta, P.K.

    1992-01-01

    This report summarizes work in the two areas of zeolites and layered double hydroxides. Results of studies on structural aspects of Ru(bpy)[sub 3][sup 2+]-zeolite Y are summarized. Photoinduced electron transfer between entrapped Ru(bpy)[sub 3][sup 2+] and methylviologen (MV) in neighboring supercages was examined. Benzylviologen was also used. Since molecules larger than 13 [angstrom] cannot be accomodated in zeolite cages, the layered double metal hydroxides (LDH) LiAl[sub 2](OH)[sub 6][sup +]X[sup [minus

  11. Characterizing the dealumination of environmentally relevant zeolites using IR, NMR and neutron diffraction techniques

    SciTech Connect

    Paffett, M.T.; Szanyi, J.; Jacubinas, R.M.; Ott, K.C.; VonDreele, R.; Hughes, C.D.; Earl, W.L.

    1997-07-01

    Results of characterization studies monitoring the sequential chemical bond breaking events, local site symmetry, and long range structural modifications of specific zeolites (H-ZSM-5, TS-1) during hydrothermal treatment of these catalyst materials are described. These characterization techniques include infrared spectroscopy of selected probe molecules, magic angle spinning NMR spectroscopy, and powder neutron diffraction. Information regarding selected examples from each of these techniques is presented and the inherent strengths of each is discussed. The experimental insight into the chemical and structural modifications of high surface area microporous catalyst materials as a function of deactivation conditions (hydrothermal conditioning) is highlighted.

  12. Modified 8-ring zeolites as catalysts

    SciTech Connect

    Bergna, H.E.; Corbin, D.R.; Sonnichsen, G.C.

    1988-06-21

    A catalyst composition is described for conversion of methanol and/or dimethylether and ammonia to dimethylamine, comprising at least one modified acidic zeolite selected from the group consisting of chabazite erionite, ZK-5, and rho, the zeolite having been modified by treatment with one or more compounds containing at least one element selected from the group consisting of silicon, aluminum, phosphorus, and boron, to deposit substantially on the external surfaces thereof at least 0.5 weight percent of the element.

  13. Tailoring the structure of hierarchically porous zeolite beta through modified orientated attachment growth in a dry gel system.

    PubMed

    Chen, Jiao; Hua, Weiming; Xiao, Yu; Huo, Qisheng; Zhu, Kake; Zhou, Xinggui

    2014-11-01

    The crystallization of zeolite beta in a dry gel system is found to follow the orientated attachment growth route, escorted with a temporal morphology change from bulky gel, through aggregation of the particulate to large zeolitic crystals. Modification of the precrystallized gel with organosilanes can be used to tune the morphology of the ultimate beta. When hexadecyltrimethoxysilane (HTS) is employed to modify precrystallized gel, a resumed secondary growth produces a hybrid mesocrystal of agglomerated nanozeolites. Combustive removal of organics leads to the formation of hierarchically porous zeolite beta of 100 to 160?nm, composed of nanocrystal building units ranging from 20 to 40?nm, with a noticeable micropore volume of 0.19?mL?g(-1) and a meso/macropore size between 5 and 80?nm. Conversely, when 1,8-bis(triethoxysilyl)octane (BTO) is utilized to modify the same precrystallized gel, assemblages of discrete beta nanozeolite of around 35?nm are generated. These assemblages construct a hierarchical zeolite beta with a micropore volume of 0.20?mL?g(-1) and auxiliary pores ranging from 5 to 100?nm. Both organosilanes bring about well-connected hierarchical pore networks. HTS has little effect on the Brønsted/Lewis acidity, whereas BTO causes a substantial reduction of strong Brønsted acid sites. The hierarchical beta zeolite-supported Pt catalyst exhibits improved catalytic performance for the hydroisomerization of n-heptane. PMID:25233842

  14. Three Mile Island zeolite vitirification demonstration program

    SciTech Connect

    Siemens, D.H.; Knowlton, D.E.; Shupe, M.W.

    1981-06-01

    The cleanup of the high-activity-level water at Three Mile Island (TMI) provides an opportunity to further develop waste management technology. Approximately 790,000 gallons of high-activity-level water at TMI's Unit-2 Nuclear Power Station will be decontaminated at the site using the submerged demineralizer system (SDS). In the SDS process, the cesium and strontium in the water are sorbed onto zeolite that is contained within metal liners. The Department of Energy has asked the Pacific Northwest Laboratory (PNL) to take a portion of the zeolite from the SDS process and demonstrate, on a production scale, that this zeolite can be vitrified using the in-can melting process. This paper is a brief overview of the TMI zeolite vitrification program. The first section discusses the formulation of a glass suitable for immobilizing SDS zeolite. The following section describes a feed system that was developed to feed zeolite to the in-can melter. It also describes the in-can melting process and the government owned facilities in which the demonstrations will take place. Finally, the schedule for completing the program activities is outlined.

  15. Thermodynamic modeling of natural zeolite stability

    SciTech Connect

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

    1997-06-01

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

  16. Zeolites: Structural Properties and Benchmarks of Feasibility

    NASA Astrophysics Data System (ADS)

    Dawson, Colby

    Zeolites are a class of microporous materials that are immensely useful as molecular sieves and catalysts. While there exist millions of hypothetical zeolite topologies, only 206 have been recognized to exist in nature, and the question remains: What distinguishes known zeolite topologies from their hypothetical counterparts? It has been found that all 206 of the known zeolites can be represented as networks of rigid perfect tetrahedra that hinge freely at the connected corners. The range of configurations over which the corresponding geometric constraints can be met has been termed the "flexibility window". Only a small percentage of hypothetical types exhibit a flexibility window, and it is thus proposed that this simple geometric property, the existence of a flexibility window, provides a reliable benchmark for distinguishing potentially realizable hypothetical structures from their infeasible counterparts. As a first approximation of the behavior of real zeolite materials, the flexibility window provides additional useful insights into structure and composition. In this thesis, various methods for locating and exploring the flexibility window are discussed. Also examined is the assumption that the tetrahedral corners are force-free. This is a reasonable approximation in silicates for Si-O-Si angles above ˜135°. However, the approximation is poor for germanates, where Ge-O-Ge angles are constrained to the range ˜120°-145°. Lastly, a class of interesting low-density hypothetical zeolites is evaluated based on the feasibility criteria introduced.

  17. Salt-occluded zeolite waste forms: Crystal structures and transformability

    SciTech Connect

    Richardson, J.W. Jr. [Argonne National Lab., IL (United States). Intense Pulsed Neutron Source Div.

    1996-12-31

    Neutron diffraction studies of salt-occluded zeolite and zeolite/glass composite samples, simulating nuclear waste forms loaded with fission products, have revealed complex structures, with cations assuming the dual roles of charge compensation and occlusion (cluster formation). These clusters roughly fill the 6--8 {angstrom} diameter pores of the zeolites. Samples are prepared by equilibrating zeolite-A with complex molten Li, K, Cs, Sr, Ba, Y chloride salts, with compositions representative of anticipated waste systems. Samples prepared using zeolite 4A (which contains exclusively sodium cations) as starting material are observed to transform to sodalite, a denser aluminosilicate framework structure, while those prepared using zeolite 5A (sodium and calcium ions) more readily retain the zeolite-A structure. Because the sodalite framework pores are much smaller than those of zeolite-A, clusters are smaller and more rigorously confined, with a correspondingly lower capacity for waste containment. Details of the sodalite structures resulting from transformation of zeolite-A depend upon the precise composition of the original mixture. The enhanced resistance of salt-occluded zeolites prepared from zeolite 5A to sodalite transformation is thought to be related to differences in the complex chloride clusters present in these zeolite mixtures. Data relating processing conditions to resulting zeolite composition and structure can be used in the selection of processing parameters which lead to optimal waste forms.

  18. Simultaneous determination of arsenic, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, and zinc in fertilizers by microwave acid digestion and inductively coupled plasma-optical emission spectrometry detection: single-laboratory validation of a modification and extension of AOAC 2006.03.

    PubMed

    Webb, Sharon; Bartos, James; Boles, Rhonda; Hasty, Elaine; Thuotte, Ethel; Thiex, Nancy J

    2014-01-01

    A single-laboratory validation study was conducted for the simultaneous determination of arsenic, cadmium, calcium, cobalt, copper, chromium, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, and zinc in all major types of commercial fertilizer products by microwave digestion and inductively coupled plasma-optical emission spectroscopy analysis. This validation study proposes an extension and modification of AOAC 2006.03. The extension is the inclusion of calcium, copper, iron, magnesium, manganese, and zinc, and the modification is incorporation of hydrochloric acid in the digestion system. This dual acid digestion utilizes both hydrochloric and nitric acids in a 3 to 9 mL volume ratio/100 mL. In addition to 15 of the 30 original validation materials used in the 2006.03 collaborative study, National Institute of Standards and Technology Standard Reference Material 695 and Magruder 2009-06 were incorporated as accuracy materials. The main benefits of this proposed method are a significant increase in laboratory efficiency when compared to the use of both AOAC Methods 965.09 and 2006.03 to achieve the same objective and an enhanced recovery of several metals. PMID:25051614

  19. Preparation of environmentally friendly alkylglucoside surfactants using zeolites as catalysts

    SciTech Connect

    Corma, A.; Iborra, S.; Miquel, S.; Primo, J. [Instituto de Tecnologia Quimica, Valencia (Spain)] [Instituto de Tecnologia Quimica, Valencia (Spain)

    1996-07-01

    Acid zeolites were evaluated for glycosidation activity of D-glucose and n-butanol. Zeolites with high Si/Al ratios such as faujasite and beta are the most suitable catalysts. 24 refs., 7 figs., 5 tabs.

  20. Branched vs. linear hydrocarbon separations with novel modified zeolites.

    SciTech Connect

    Gray, Gary R.; Noble, Richard D.; Nenoff, Tina Maria; Arruebo, Manuel; Ulutagay-Kartin, Mutlu; Anderson, Thomas M.

    2004-08-01

    Conclusions of this paper are: (1) Adsorption/desorption on bulk unmodified zeolites showed isoprene adsorbed by zeolite-L and n-pentane adsorbed by zeolite-Y and ZSM-5; (2) Bulk carbonization is used to passivate zeolite activity toward organic adsorption/decomposition; (3) Based on the bulk modified zeolite separation results, we have determined that the MFI type has the most potential for isoprene enrichment; (4) Modified MFI type membranes are jointly made by Sandia and the Univ. of Colorado. Separation experiments are performed by Goodyear Chemical; (5) Isoprene/n-pentane separations have been demonstrated by using both zeolite membranes and modified bulk zeolites at various temperatures on the Goodyear Pilot-scale unit; and (6) Target zeolite membrane separations values of 6.7% isoprene enrichment have been established by economic analysis calculations by Burns & McDonnell.

  1. Branched vs. linear hydrocarbon separations with novel modified zeolites.

    SciTech Connect

    Gray, Gary R.; Noble, Richard D.; Nenoff, Tina Maria; Arruebo, Manuel; Ulutagay-Kartin, Mutlu; Johnston, Kaylynn; Anderson, Thomas M.

    2005-06-01

    The conclusions of this paper are: (1) Adsorption/desorption on bulk unmodified zeolites showed isoprene adsorbed by zeolite-L and n-pentane adsorbed by zeolite-Y and ZSM-5; (2) Bulk carbonization is used to passivate zeolite activity toward organic adsorption/decomposition; (3) Based on the bulk modified zeolite separation results, we have determined that the MFI type has the most potential for isoprene enrichment; (4) Modified MFI type membrane are jointly made by Sandia and the Univ. of Colorado. Separation experiments are performed by Goodyear Chemical; (5) Isoprene/n-pentane separations have been demonstrated by using both zeolite membranes and modified bulk zeolites at various temperatures on the Goodyear Pilot-scale unit; and (6) Target zeolite membrane separations values of 6.7% isoprene enrichment have been established by economic analysis calculations by Burns & McDonnell.

  2. The structure of actinide ions exchanged into native and modified zeolites and clays

    SciTech Connect

    Wasserman, S. R.; Soderholm, L.; Giaquinta, D. M.

    2000-02-16

    X-ray absorption spectroscopy (XAS) has been used to investigate the structure and valence of thorium (Th{sup 4+}) and uranyl (UO{sub 2}{sup 2+}) cations exchanged into two classes of microporous aluminosilicate minerals: zeolites and smectite clays. XAS is also employed to examine the fate of the exchanged cations after modification of the mineral surface using self-assembled organic films and/or exposure to hydrothermal conditions. These treatments serve as models for the forces that ultimately determine the chemical fate of the actinide cations in the environment. The speciation of the cations depends on the pore size of the aluminosilicate, which is fixed for the zeolites and variable for the smectites.

  3. Separation of xylene mixtures using polyurethane—zeolite composite membranes

    Microsoft Academic Search

    Shingjiang Jessie Lue; Tsai-hsin Liaw

    2006-01-01

    Fractionation of o- and p-xylene isomeric mixtures was performed using pervaporation (PV) with polyurethane (PU) membranes containing ZSM zeolite. The xylene vapor sorption isotherms exhibited a Henry's law relationship in this PU–zeolite blend. In binary solutions the individual xylene uptake was also proportional to the solvent composition. Although incorporating zeolite into the PU–zeolite membrane rendered a decrease in xylene solubility

  4. Durability of Zeolite Against Repeated Activation Treatments with Microwave Heating

    Microsoft Academic Search

    Tatsuo Ohgushi; Mayumi Nagae

    2005-01-01

    The durability of zeolite X against repeated treatments with microwave heating was studied, and properties of the zeolite as desiccant were compared and assessed with those of the most popular commercial desiccants (calcium chloride) for home use. Mixed cationic forms of zeolite with a ratio of Na-X\\/Ca-X = 5 g\\/45 g in a full hydration was used to achieve desirable

  5. New vistas in zeolite and molecular sieve catalysis

    Microsoft Academic Search

    Mark E. Davis

    1993-01-01

    There is a close connection between the microscopic structures and the macroscopic properties of zeolite catalysts. The ability to control the zeolite properties through synthetic efforts will continue to be of great importance. At present, the control of zeolite properties mainly involves molecular level manipulations of structural features, e.g., pore size and location of active sites. That is to say,

  6. Formation of NaA and -X zeolites from waste solutions in conversion of coal fly ash to zeolites

    Microsoft Academic Search

    Hidekazu Tanaka; Yasuhiko Sakai; Ryozi Hino

    2002-01-01

    Na-A and -X zeolites were synthesized from waste solutions in conversion of coal fly ash (Fa) to zeolite. The amorphous SiO2 and Al2O3 of Fa were completely dissolved to form Po, Pt, and Pc type zeolites in NaOH solutions at 85°C. Only 24% of Si4+ eluted from Fa were converted to the zeolites and the remaining waste solutions contained high

  7. Zeolite-supported metal oxide sorbents for hot-gas desulfurization

    SciTech Connect

    Gasper-Galvin, L.D. [Dept. of Energy, Morgantown, WV (United States). Federal Energy Technology Center] [Dept. of Energy, Morgantown, WV (United States). Federal Energy Technology Center; Atimtay, A.T. [Middle East Technical Univ., Ankara (Turkey). Environmental Engineering Dept.] [Middle East Technical Univ., Ankara (Turkey). Environmental Engineering Dept.; Gupta, R.P. [Research Triangle Inst., NC (United States)] [Research Triangle Inst., NC (United States)

    1998-10-01

    This paper describes the results of the development of supported mixed-metal oxide sorbents for hot-gas desulfurization capable of withstanding multiple sulfidation/regeneration cycles at 871 C (1600 F). The sorbents consisted of various combinations of copper, molybdenum, and/or manganese oxides supported on a high silica-containing zeolite. These sorbents were tested in a fixed-bed reactor with simulated coal gas at 205 kPa (15 psig). The combination of all three metal oxides displayed synergism in enhancing efficiency for H{sub 2}S removal and improved the crush strength on the pellets. Copper oxide was the most active component for reaction with H{sub 2}S, while molybdenum and manganese oxides appeared to act as catalysts/promoters. During multicycle testing, this ternary metal oxide sorbent retained its reactivity and mechanical strength.

  8. Daily copper supplement effects on copper balance in trained subjects during prolonged restriction of muscular activity.

    PubMed

    Zorbas, Y G; Charapakin, K P; Kakurin, V J; Kuznetsov, N K; Federov, M A; Popov, V K

    1999-08-01

    The aim of this study was to assess the effect of a daily intake of copper supplements on negative copper balance during prolonged exposure to hypokinesia (decreased number of kilometers per day). During hypokinesia (HK), negative copper balance is shown by increased, not by decreased, serum copper concentration, as it happens in other situations. Studies were done during a 30-d prehypokinetic period and a 364-d hypokinetic period. Forty male trained volunteers aged 22-26 yr with a peak oxygen uptake of 66.4 mL/min/kg and with an average of 13.7 km/d running distance were chosen as subjects. They were equally divided into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SACS and SHKS groups took 0.09 mg copper carbonate/kg body weight daily. The SHKS and UHKS groups were maintained under an average running distance of 1.7 km/d, whereas the SACS and UACS groups did not experience any modifications in their normal training routines. During the 30-d prehypokinetic period and the 346-d hypokinetic period, urinary excretion of copper, calcium, and magnesium and serum concentrations of copper, calcium, and magnesium were measured. Copper loss in feces and copper balance was also determined. In both UHKS and SHKS groups, urinary excretion of copper, calcium, and magnesium and concentrations of copper, magnesium, and calcium in serum increased significantly when compared with the SACS and UACS groups. Loss of copper in feces was also increased significantly in the SHKS and UHKS groups when compared with the UACS and SACS groups. Throughout the study, the copper balance was negative in the SHKS and UHKS groups, whereas in the SACS and UACS groups, the copper balance was positive. It was concluded that a daily intake of copper supplements cannot be used to prevent copper deficiency shown by increased copper concentration. Copper supplements also failed to prevent negative copper balance and copper losses in feces and urine in endurance-trained subjects during prolonged exposure to HK. PMID:10433342

  9. Copper Cleanup

    NSDL National Science Digital Library

    2013-12-05

    In this hands-on experiment, kids use chemistry to explore whether acids or bases are better at restoring a penny’s shine. Kids follow the scientific process to test a common household cleaning products alongside ketchup, cola, and other kitchen staples, and may be surprised by the results! A downloadable data sheet is available on the Copper Cleanup activity resources page.

  10. A stable lotus-leaf-like water-repellent copper

    Microsoft Academic Search

    Zhi-Guang Guo; Wei-Min Liu; Bao-Lian Su

    2008-01-01

    The stable lotus-leaf-like superhydrophobic copper was fabricated by means of a very simple and industrially up scalable method. Under both the growth of CuO microcrystals on the surface and the chemical modification, the wettability of the copper substrate changed from hydrophilic to water-repellent superhydrophobic, with surface hierarchical structures similar to that of lotus leaf.

  11. A stable lotus-leaf-like water-repellent copper

    NASA Astrophysics Data System (ADS)

    Guo, Zhi-Guang; Liu, Wei-Min; Su, Bao-Lian

    2008-02-01

    The stable lotus-leaf-like superhydrophobic copper was fabricated by means of a very simple and industrially up scalable method. Under both the growth of CuO microcrystals on the surface and the chemical modification, the wettability of the copper substrate changed from hydrophilic to water-repellent superhydrophobic, with surface hierarchical structures similar to that of lotus leaf.

  12. Chemical evaluation of hypothetical uninodal zeolites.

    PubMed

    Foster, Martin D; Delgado Friedrichs, Olaf; Bell, Robert G; Almeida Paz, Filipe A; Klinowski, Jacek

    2004-08-11

    Optimized structural parameters, framework energies relative to alpha-quartz, and volumes accessible to sorption have been calculated for the systematically enumerated hypothetical uninodal zeolitic structures (structures in which all tetrahedral sites are equivalent). The structures were treated as silica polymorphs, and their energies were minimized using the GULP program with the Sanders-Catlow silica potential. Results are given for 164 structures, which include all 21 known uninodal zeolites, two known minerals (tridymite and cristobalite), and 78 unknown zeolite topologies. Twenty-three hypothetical structures were identified as chemically feasible. Complete structural information is provided, and several structures are discussed in detail. The results will assist in the design of new synthetic routes and in the identification of newly synthesized materials. PMID:15291580

  13. Crystal engineering of zeolites with graphene

    NASA Astrophysics Data System (ADS)

    Gebhardt, Paul; Pattinson, Sebastian W.; Ren, Zhibin; Cooke, David J.; Elliott, James A.; Eder, Dominik

    2014-06-01

    Achieving control over the morphology of zeolite crystals at the nanoscale is crucial for enhancing their performance in diverse applications including catalysis, sensors and separation. The complexity and sensitivity of zeolite synthesis processes, however, often make such control both highly empirical and difficult to implement. We demonstrate that graphene can significantly alter the morphology of titanium silicalite (TS-1) particles, in particular being able to reduce their dimensions from several hundreds to less than 10 nm. Through electron microscopy and molecular mechanics simulations we propose a mechanism for this change based on the preferential interaction of specific TS-1 surfaces with benzyl-alcohol-mediated graphene. These findings suggest a facile new means of controlling the zeolite morphology and thereby also further demonstrate the potential of graphene in hybrid materials. Moreover, the generality of the mechanism points the way to a new avenue of research in using two-dimensional materials to engineer functional inorganic crystals.Achieving control over the morphology of zeolite crystals at the nanoscale is crucial for enhancing their performance in diverse applications including catalysis, sensors and separation. The complexity and sensitivity of zeolite synthesis processes, however, often make such control both highly empirical and difficult to implement. We demonstrate that graphene can significantly alter the morphology of titanium silicalite (TS-1) particles, in particular being able to reduce their dimensions from several hundreds to less than 10 nm. Through electron microscopy and molecular mechanics simulations we propose a mechanism for this change based on the preferential interaction of specific TS-1 surfaces with benzyl-alcohol-mediated graphene. These findings suggest a facile new means of controlling the zeolite morphology and thereby also further demonstrate the potential of graphene in hybrid materials. Moreover, the generality of the mechanism points the way to a new avenue of research in using two-dimensional materials to engineer functional inorganic crystals. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00320a

  14. Natural zeolite reactivity towards ozone: the role of compensating cations.

    PubMed

    Valdés, Héctor; Alejandro, Serguei; Zaror, Claudio A

    2012-08-15

    Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L(-1)). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH(3)-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal. PMID:22633878

  15. Behavior Modification

    Microsoft Academic Search

    Robert M. Anderson

    \\u000a Behavioral problems may be associated with disorders of the central nervous system. The therapy of choice for such problems\\u000a is often a behavior modification program possibly supplemented by psychoactive medications. Behavior modification should be\\u000a done by health care personnel with appropriate training and competence. It is essential that all staff involved in a behavior-change\\u000a program have a clear understanding of

  16. Surface modification of composites with metal nanoparticles

    Microsoft Academic Search

    N. V. Sotskaya; S. V. Makarov; O. V. Dolgikh; V. M. Kashkarov; A. S. Len’shin; E. A. Kotlyarova

    2010-01-01

    This work examines the possibility of using copper, nickel, and cobalt nanoparticles in the electrodeposition of nickel coatings\\u000a and for surface modification of porous silicon, and also colloidal silver particles for surface modification of silver-containing\\u000a polymer-matrix composites. It is shown that the deposition of metal nanoparticles may influence the morphology, electronic\\u000a structure, and phase composition of the surface and the

  17. Dispersion strengthened copper

    DOEpatents

    Sheinberg, H.; Meek, T.T.; Blake, R.D.

    1990-01-09

    A composition of matter is described which is comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide. A method for making this composition of matter is also described. This invention relates to the art of powder metallurgy and, more particularly, it relates to dispersion strengthened metals.

  18. On the modification of solid adsorbents with volatile organics II. The role of the layer adsorbed

    Microsoft Academic Search

    M. M. Kope?ni; M. Todorovi?; J. J. ?omor; R. J. Laub

    1988-01-01

    This paper presents a continuation of our research dedicated to solid-adsorbent surface modification with what are commonly regarded as volatile and easily eluted organic compounds. Two porous adsorbents were used: natural zeolite (clinoptilolite) and alumina, while the adsorbates employed were n-hepatane and benzene. The results show that a simple injection of volatile adsorbate greatly alters the solid surface adsorption properties.

  19. Chemical interactions in multimetal/zeolite catalysts

    SciTech Connect

    Sachtler, W.M.H.

    1992-02-07

    Mechanistic explanations have been found for the migration of atoms and ions through the zeolite channels leading to specific distribution of ions and the metal clusters. In this report, we summarize the state of understanding attained on a number of topics in the area of mono- and multimetal/zeolite systems, to which our recent research has made significant contributions. The following topics are discussed: (1) Formation of isolated metal atoms in sodalite cages; (2) differences of metal/zeolite systems prepared by ion reduction in channels or via isolated atoms; (3) rejuvenation of Pd/NaY and Pd/HY catalysts by oxidative redispersion of the metal; (4) formation of mono- or bimetal particles in zeolites by programmed reductive decomposition of volatile metal complexes; (5) cation-cation interaction as a cause of enhanced reducibility; (6) formation of palladium carbonyl clusters in supercages; (7) enhanced catalytic activity of metal particle-proton complexes for hydrocarbon conversion reactions; (8) stereoselectivity of catalytic reactions due to geometric constraints of particles in cages.

  20. MERCURY SEPARATION FROM POLLUTANT WATER USING ZEOLITES

    EPA Science Inventory

    Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. In the present work, the potential use of a variety of synthetic zeolites for removal of arsenic from water has been examined at room temperature. Experiments have...

  1. Silver clusters and chemistry in zeolites

    Microsoft Academic Search

    Tao Sun; Karl Seff

    1994-01-01

    The spectroscopic work done on silver clusters trapped in solid noble gas matrices at low temperature has been extensively reviewed by Ozin, and Henglein has done the same for photochemical studies of colloidal silver particles in solution. This article will review the chemistry of silver in zeolite hosts, including the synthesis and structures of silver clusters. 127 refs.

  2. Silver clusters and chemistry in zeolites

    SciTech Connect

    Sun, T.; Seff, K. (Univ. of Hawaii, Honolulu, HI (United States). Dept. of Chemistry)

    1994-06-01

    The spectroscopic work done on silver clusters trapped in solid noble gas matrices at low temperature has been extensively reviewed by Ozin, and Henglein has done the same for photochemical studies of colloidal silver particles in solution. This article will review the chemistry of silver in zeolite hosts, including the synthesis and structures of silver clusters. 127 refs.

  3. Conversion of Ethanol to Hydrocarbons on Hierarchical HZSM-5 Zeolites

    SciTech Connect

    Ramasamy, Karthikeyan K.; Zhang, He; Sun, Junming; Wang, Yong

    2014-12-15

    This study reports synthesis, characterization, and catalytic activity of the nano-size hierarchical HZSM-5 zeolite with high mesoporosity produced via a solvent evaporation procedure. Further, this study compares hierarchical zeolites with conventional HZSM-5 zeolite with similar Si/Al ratios for the ethanol-to-hydrocarbon conversion process. The catalytic performance of the hierarchical and conventional zeolites was evaluated using a fixed-bed reactor at 360 °C, 300 psig, and a weight hourly space velocity of 7.9 h-1. For the low Si/Al ratio zeolite (~40), the catalytic life-time for the hierarchical HZSM-5 was approximately 2 times greater than the conventional HZSM-5 despite its coking amount deposited 1.6 times higher than conventional HZSM-5. For the high Si/Al ratio zeolite (~140), the catalytic life-time for the hierarchical zeolite was approximately 5 times greater than the conventional zeolite and the amount of coking deposited was 2.1 times higher. Correlation was observed between catalyst life time, porosity, and the crystal size of the zeolite. The nano-size hierarchical HZSM-5 zeolites containing mesoporosity demonstrated improved catalyst life-time compared to the conventional catalyst due to faster removal of products, shorter diffusion path length, and the migration of the coke deposits to the external surface from the pore structure.

  4. Copper in diet

    MedlinePLUS

    Diet - copper ... Copper works with iron to help the body form red blood cells. It also helps keep the ... organ meats (kidneys, liver) are good sources of copper. Dark leafy greens, dried fruits such as prunes, ...

  5. Copper Extraction Demonstration

    NSDL National Science Digital Library

    Summary This demonstration uses sulfuric acid and crushed copper ore (malachite) to produce a solution of copper sulfate and carbonic acid in a beaker. When a freshly sanded nail is dropped into the copper sulfate ...

  6. Molecular Structure of Copper

    NSDL National Science Digital Library

    2003-04-10

    Man has known of copper since antiquity. Copper is known for its unique reddish hue, its good electrical and thermal conductivity, and widespread abundance. It is malleable and extremely ductile. Copper melts at 1357 degrees kelvin and boils at 2840 degrees kelvin. Copper crystals are commonly found in cubic and dodecahedral forms. Copper is widely used in wiring and electronics. Two important alloys of copper are brass and bronze. Also, all American coins are now made of copper alloys. Humans require trace amounts of copper; larger doses result in poisoning.

  7. Changes in copper concentrations affect the protein levels but not the mRNA levels of copper chaperones in human umbilical vein endothelial cells.

    PubMed

    Dong, Daoyin; Xu, Xinhua; Yin, Wen; Kang, Y James

    2014-03-01

    Copper chaperones are critical regulators of intracellular copper metabolism and distribution. The present study was undertaken to investigate the effects of changes in copper concentrations on the abundance of copper chaperones. Human umbilical vein endothelial cells (HUVECs) were treated with siRNA targeting copper transporter 1 (CTR1) or tetraethylenepentamine (TEPA) to decrease, or with copper sulfide to increase, intracellular copper concentrations, assayed using an atomic absorption spectrophotometer. Western blot analyses showed that CTR1 silencing or TEPA treatment increased the protein levels of copper chaperone ATOX1 and copper chaperone for superoxide dismutase 1 (CCS-1), but decreased copper chaperone for cytochrome c oxidase (COX17). In contrast, copper supplementation decreased the protein levels of ATOX1 and CCS-1 and increased COX17. Real-time RT-PCR analyses found no difference in the mRNA levels of the copper chaperones examined under the conditions defined above. This study thus demonstrated that changes in copper concentrations alter the protein levels, but not the mRNA levels, of copper chaperones, suggesting a role of copper in the post-translational modification of these proteins. PMID:24343031

  8. Interaction of Microwaves with Synthetic Type A Zeolite Containing Water

    NASA Astrophysics Data System (ADS)

    Tanaka, Masahiro; Takayama, Sadatsugu; Sano, Saburo

    2013-11-01

    A synthetic honeycomb type A zeolite adsorbent was regenerated through microwave irradiation in a single-mode cavity microwave at 2.46 GHz. The regeneration mechanism was investigated by comparing the heating properties, thermogravimetric properties, and dielectric properties of the synthetic zeolite samples. The hydrated zeolite sample was easily heated to over 200 °C, although a difference in the impedance matching frequency of only 0.01 GHz sharply reduced the maximum heating and increased the regeneration time. The adsorbed water in the hydrated zeolite initially acted as a heating agent by absorbing microwave energy, because the dielectric loss factor of water is higher than that of synthetic zeolite around 2.45 GHz. From 50 to 250 °C, the zeolite itself also absorbed microwave energy.

  9. Zeolite and swine inoculum effect on poultry manure biomethanation

    NASA Astrophysics Data System (ADS)

    Kougias, P. G.; Fotidis, I. A.; Zaganas, I. D.; Kotsopoulos, T. A.; Martzopoulos, G. G.

    2013-03-01

    Poultry manure is an ammonia-rich substrate that inhibits methanogenesis, causing severe problems to the anaerobic digestion process. In this study, the effect of different natural zeolite concentrations on the mesophilic anaerobic digestion of poultry waste inoculated with well-digested swine manure was investigated. A significant increase in methane production was observed in treatments where zeolite was added, compared to the treatment without zeolite.Methane production in the treatment with 10 g dm-3 of natural zeolite was found to be 109.75% higher compared to the treatment without zeolite addition. The results appear to be influenced by the addition of zeolite, which reduces ammonia toxicity in anaerobic digestion and by the ammonia-tolerant swine inoculum.

  10. Zeolite catalysis in conversion of cellulosics. Annual report

    SciTech Connect

    Tsao, G.T.

    1994-02-01

    The authors have studied the kinetics of oxylose/xylulose isomerization in significant detail over a variety of zeolites and obtained the pseudo-first order reaction rate constants. The authors have found that HY zeolite is still the best material and zeolites are more selective than homogeneous acid catalysts where decomposition of the sugar compounds is much faster. They have completed, as described in the Year 2 Work Plan, the study of cellobiose hydrolysis with an ion exchange resin. The kinetics of the solid-catalyzed reaction is qualitatively similar to that for catalysis by homogeneous acids. The planned program of NMR studies has revealed the dynamics of sugar molecules within the zeolite cavities. Two chemisorbed and a physisorbed state have been identified in HY zeolite. A new state, accounting for as much as a half of the sugar, has been found in ZSM-5 zeolite.

  11. Advanced zeolites used in FCC catalysts boost motor octane number

    SciTech Connect

    Letzsch, W.S.; Magee, J.S.; Upson, L.L.; Valeri, F. (Katalistiks International, Baltimore, MD (US))

    1988-10-31

    Fluid catalytic cracking catalysts that contain an advanced zeolite called LZ-210, have been shown, by commercial trials, to increase the motor octane number (MON) of the FCC gasoline produced. The zeolite crystal utilizes lower unit cell size, lower sodium in the zeolite, less alumina debris in the zeolite structure, and silica reinsertion into the zeolite structure to accomplish the MON increase. Data from commercial trials are presented to support the MON increases, along with some explanations of how the advanced zeolite accomplishes them. A strong gasoline market and the removal of lead have combined to place a premium on clear gasoline octanes. Because gasoline from fluid catalytic cracking units is the largest segment of the refinery pool (up to 40%), its octane numbers are particularly important. Traditional emphasis has been on the research octance number (RON) but motor octanes frequently limit the blending process.

  12. Atomic sites and stability of Cs+ captured within zeolitic nanocavities

    NASA Astrophysics Data System (ADS)

    Yoshida, Kaname; Toyoura, Kazuaki; Matsunaga, Katsuyuki; Nakahira, Atsushi; Kurata, Hiroki; Ikuhara, Yumi H.; Sasaki, Yukichi

    2013-08-01

    Zeolites have potential application as ion-exchangers, catalysts and molecular sieves. Zeolites are once again drawing attention in Japan as stable adsorbents and solidification materials of fission products, such as 137Cs+ from damaged nuclear-power plants. Although there is a long history of scientific studies on the crystal structures and ion-exchange properties of zeolites for practical application, there are still open questions, at the atomic-level, on the physical and chemical origins of selective ion-exchange abilities of different cations and detailed atomic structures of exchanged cations inside the nanoscale cavities of zeolites. Here, the precise locations of Cs+ ions captured within A-type zeolite were analyzed using high-resolution electron microscopy. Together with theoretical calculations, the stable positions of absorbed Cs+ ions in the nanocavities are identified, and the bonding environment within the zeolitic framework is revealed to be a key factor that influences the locations of absorbed cations.

  13. Atomic sites and stability of Cs+ captured within zeolitic nanocavities

    PubMed Central

    Yoshida, Kaname; Toyoura, Kazuaki; Matsunaga, Katsuyuki; Nakahira, Atsushi; Kurata, Hiroki; Ikuhara, Yumi H.; Sasaki, Yukichi

    2013-01-01

    Zeolites have potential application as ion-exchangers, catalysts and molecular sieves. Zeolites are once again drawing attention in Japan as stable adsorbents and solidification materials of fission products, such as 137Cs+ from damaged nuclear-power plants. Although there is a long history of scientific studies on the crystal structures and ion-exchange properties of zeolites for practical application, there are still open questions, at the atomic-level, on the physical and chemical origins of selective ion-exchange abilities of different cations and detailed atomic structures of exchanged cations inside the nanoscale cavities of zeolites. Here, the precise locations of Cs+ ions captured within A-type zeolite were analyzed using high-resolution electron microscopy. Together with theoretical calculations, the stable positions of absorbed Cs+ ions in the nanocavities are identified, and the bonding environment within the zeolitic framework is revealed to be a key factor that influences the locations of absorbed cations. PMID:23949184

  14. Chemical Interactions in Multimetal/Zeolite Catalysts

    SciTech Connect

    Sachtler, Wolfgang M. H.

    2004-04-16

    This two-year project has led to a significant improvement in the fundamental understanding of the catalytic action of zeolite-supported redox catalysts. It turned out to be essential that we could combine four strategies for the preparation of catalysts containing transition metal (TM) ions in zeolite cavities: (1) ion exchange from aqueous solution; (2) chemical vapor deposition (CVD) of a volatile halide onto a zeolite in its acidic form; (3) solid state ion exchange; and (4) hydrothermal synthesis of a zeolite having TM ions in its lattice, followed by a treatment transporting these ions to ''guest positions''. Technique (2) enables us to position more TM ions into cavities than permitted by the conventional technique (1).viz one positive charge per Al centered tetrahedron in the zeolite lattice. The additional charge is compensated by ligands to the TM ions, for instance in oxo-ions such as (GaO){sup +} or dinuclear [Cu-O-Cu]{sup 2+}. While technique (3) is preferred over CVD where volatile halides are not available, technique (4) leads to rather isolated ''ex lattice'' oxo-ions. Such oxo-ions tend to be mono-nuclear, in contrast to technique (2) which preferentially creates dinuclear oxo-ions of the same TM element. A favorable element for the present research was that the PI is also actively engaged in a project on the reduction of nitrogen oxides, sponsored by EMSI program of the National Science Foundation and the US Department of Energy, Office of Science. This combination created a unique opportunity to test and analyze catalysts for the one step oxidation of benzene to phenol and compare them with catalysts for the reduction of nitrogen oxides, using hydrocarbons as the reductant. In both projects catalysts have been used which contain Fe ions or oxo-ions in the cavities the zeolite MFI, often called ZSM-5. With Fe as the TM-element and MFI as the host zeolite we found that catalysts with high Fe content, prepared by technique (2) were optimal for the De-NO{sub x} reaction, but extremely unselective for benzene oxidation to phenol. Conversely, the catalysts prepared with (4) had the highest turnover frequency for benzene oxidation, but performed very poorly for NO{sub x} reduction with so-butane. In fact the Fe concentration in the former catalysts were so low that it was necessary to design a special experimental program for the sole purpose of showing that it is really the Fe which catalyzes the benzene oxidation, not some acid center as has been proposed by other authors. For this purpose we used hydrogen sulfide to selectively poison the Fe sites, without deactivating the acidic sites. In addition we could show that the hydrothermal treatment of catalysts prepared by technique (4) is essential to transform iron ions in the zeolite lattice to ''ex lattice ions'' in guest positions. That line of the work required very careful experimentation, because a hydrothermal treatment of a zeolite containing Fe ions in its cavities can also lead to agglomeration of such ions to nano-particles of iron oxide which lowers the selectivity for the desired formation of phenol. This part of the program showed convincingly that indeed Fe is responsible for the benzene oxidation catalysis. The results and conclusion of this work, including the comparison of different catalysts, was published in a number of papers in the scientific literature, listed in the attached list. In these papers also our analysis of the reaction orders and the possible mechanism of the used test reaction are given.

  15. Treatment of Acid Mine Drainage Using Fly Ash Zeolite

    Microsoft Academic Search

    Bably Prasad; Robert J. G. Mortimer

    2011-01-01

    In this paper, two Indian fly ashes (from Talcher and Ramagundam) were converted into zeolites and both the raw fly ash and\\u000a zeolite were used to treat two British acidic mine waters. The results demonstrate that fly ash zeolites are more effective\\u000a than raw fly ash for treatment of acid mine drainage. Fly ash has been found effective for removal

  16. Zeolite-combined plasma reactor for decomposition of toluene

    Microsoft Academic Search

    S.-M. Oh; H.-H. Kim; H. Einaga; A. Ogata; S. Futamura; D.-W. Park

    2006-01-01

    Toluene was decomposed in a surface-discharge plasma reactor and the combined effect of zeolite in the plasma reactor was studied. The decomposition of toluene and the product compositions depended on the reactor configuration and the capacity of zeolite to adsorb toluene. Toluene adsorbed on the zeolite (micro-pores) was not properly decomposed in the head of the plasma (P1), while it

  17. Heat of adsorption of ammonia by type E zeolites

    Microsoft Academic Search

    S. S. Khvoshchev; V. E. Skazyvaev; S. P. Zhdanov; I. V. Karetina

    1978-01-01

    Conclusions 1.Measurement has been made of the heat evolved in the adsorption of ammonia on calcium, calcium-sodium, and sodium forms of type E zeolites.2.The Ca2+ cations of type E zeolites are more active which respect to adsorbing ammonia molecules than are the Ca2+ ions of synthetic faujasites and type A zeolites.3.The results obtained are analyzed in terms of lattice position

  18. Microwave synthesis of LTA zeolite membranes without seeding

    Microsoft Academic Search

    Yanshuo Li; Hongliang Chen; Jie Liu; Weishen Yang

    2006-01-01

    A new method called “in-situ aging—microwave synthesis” was developed for zeolite membrane synthesis. High quality LTA zeolite membranes were successfully microwave-synthesized without seeding by this method. It was found that the formed zeolite layer was composed of sphere grains with undefined crystal facets. The necessity of in-situ aging was discussed. The effects of synthesis parameters including in-situ aging temperature, time

  19. Tetraethylenepentamine embedded zeolite A for carbon dioxide adsorption.

    PubMed

    Kim, Young-Ki; Mo, Yong-Hwan; Lee, Jun; You, Hyo-Sang; Yi, Chang-Keun; Park, Young Cheol; Park, Sang-Eon

    2013-04-01

    Tetraethylenepentamine (TEPA) embedded zeolite A crystals were synthesized by using TEPA and the preformed zeolite A precursor under the microwave irradiation. The presence of TEPA in zeolite A crystal was confirmed by TG analysis and FTIR, Raman spectra. The CO2 adsorptive behavior of TEPA embedded zeolite A samples was investigated by CO2 isotherms measured at 25 degrees C comparing with zeolite A. The optimum CO2 sorption capacity was found in the case of 7.5% TEPA embedded zeolite A, which showed 3.75 mmol g(-1) where as the zeolite A showed less CO2 adsorption capacity of 2.88 mmol g(-1). The adsorption capacity of TEPA embedded Zeolite A was sustained up to 90% during 4 cycles of temperature swing adsorption (TSA) from 40 degrees C to 140 degrees C, indicating that the TEPA embedded Zeolite A was found to be useful as one of the application to solid amine adsorbent for CO2. PMID:23763147

  20. Home modification.

    PubMed

    McCullagh, Marjorie Cook

    2006-10-01

    Almost 50 million Americans--about one in five--live with a mental or physical disability, many in homes that are inconvenient, restrictive, or dangerous for them. Modifying the home using universal (barrier-free) design, architectural accessibility, and other such concepts can reduce the risk of falls and improve overall function. Nurses can be involved by assessing patients' living quarters and recommending specific modifications. PMID:17016095

  1. Isoprenoid Modifications

    Microsoft Academic Search

    Uyen T. T. Nguyen; Andrew Goodall; Kirill Alexandrov; Daniel Abankwa

    \\u000a Up to 2% of mammalian proteome is post-translationally modified with isoprenoid lipids. Many of these molecules are key regulators\\u000a of signaling pathways involved in cellular homeostasis. Appropriate signaling by prenylated proteins requires a combination\\u000a of correct expression levels, efficient post-translational modification, correct subcellular trafficking and nanolocalisation\\u000a as well as an appropriately regulated activation\\/deactivation cycle. Aberrant signaling by prenylated proteins can

  2. LAYER-BY-LAYER ASSEMBLY OF NANOZEOLITE BASED ON POLYMERIC MICROSPHERE: ZEOLITE COATED SPHERE AND HOLLOW ZEOLITE SPHERE

    Microsoft Academic Search

    Wuli Yang; Xingdong Wang; Yi Tang; Yajun Wang; Chen Ke; Shoukuan Fu

    2002-01-01

    Zeolite ?, silicalite-1, ZSM-5, and TS-1 coated spheres have been prepared successfully through layer-by-layer assembly of nanozeolite\\/polymer multilayers on polystyrene (PS) microspheres, and hollow zeolite spheres have been obtained by removal of the core by calcination. In the adsorption process of nanozeolites onto the polyelectrolyte-modified template spheres, it has been found that zeta potential of the zeolite colloidal solution that

  3. Pf/Zeolite Catalyst for Tritium Stripping

    SciTech Connect

    Hsu, R.H.

    2001-03-26

    This report described promising hydrogen (protium and tritium) stripping results obtained with a Pd/zeolite catalyst at ambient temperature. Preliminary results show 90-99+ percent tritium stripping efficiency may be obtained, with even better performance expected as bed configuration and operating conditions are optimized. These results suggest that portable units with single beds of the Pd/zeolite catalyst may be utilized as ''catalytic absorbers'' to clean up both tritium gas and tritiated water. A cart-mounted prototype stripper utilizing this catalyst has been constructed for testing. This portable stripper has potential applications in maintenance-type jobs such as tritium line breaks. This catalyst can also potentially be utilized in an emergency stripper for the Replacement Tritium Facility.

  4. Olefins from methanol by modified zeolites

    SciTech Connect

    Inui, T.; Takegami, Y.

    1982-11-01

    Compares the effects of modified catalysts (ZSM-34 and ZSM-5 class zeolites) on methanol conversion to olefins (MTO) with regard to olefin selectivity and cost. Presents tables with prices of olefins in the US and Japan; comparison of methanol-cracking with naphtha cracking; methanol conversion data for Type-1, Type-II and reference catalysts; hydrocarbon distribution from MTO processes; and speculative economics for MTO processes of Concept-1 and 2. Diagrams the proposed MTO process scheme. Scanning electron micrographs of the zeolite catalysts are shown. Graphs indicate the change of ethylene prices in the US since 1978 and forecast ethylene prices in several countries. Concludes that the prices of ethylene for both MTO processes examined compare favorably with products of conventional processes.

  5. Electrical Response of PEDOT-PSS/FAU Zeolite Composites toward SO2: Controlling the Adsorption Properties of FAU Zeolite

    NASA Astrophysics Data System (ADS)

    Chanthaanont, Pojjawan; Sirivat, Anuvat

    2012-02-01

    In our work, we propose to combine a conductive polymer, Poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT-PSS), with FAU zeolites to investigate the potential of the composites for use as SO2 sensing materials.Composites with PEDOT-PSS as a matrix containing faujasite zeolites of various cation types (divalent transition metal ions: Fe^2+, Co^2+, Ni^2+ and Cu^2+), were fabricated to investigate the effect of the cation type of the faujasite zeolites on the electrical conductivity response when exposed to SO2. The composite was tested through repeated sensing and recovery processes to investigate the reversibility and reproducibility. During the recovery process, the electrical conductivity of the composites were recovered, which proves that the sensing characteristics are repeatable. Responses and the interaction mechanism of the conductive polymer/zeolite composites were investigated. The composite with 20% (v/v) of zeolite content gives the highest sensitivity. The electrical conductivity responses of PEDOT-PSS/Zeolite composites can be altered due to the available adsorption sites for gas molecules. The addition of zeolites to the pristine PEDOT-PSS improved the electrical conductivity sensitivity of the composites by enhancing the interaction between PEDOT-PSS and SO2. The type of cation in the zeolite pores effected the sensitivity of the composites, depending on the acidity of the ion-exchanged zeolites.

  6. Vitrification of copper flotation waste.

    PubMed

    Karamanov, Alexander; Aloisi, Mirko; Pelino, Mario

    2007-02-01

    The vitrification of an hazardous iron-rich waste (W), arising from slag flotation of copper production, was studied. Two glasses, containing 30wt% W were melted for 30min at 1400 degrees C. The first batch, labeled WSZ, was obtained by mixing W, blast furnace slag (S) and zeolite tuff (Z), whereas the second, labeled WG, was prepared by mixing W, glass cullet (G), sand and limestone. The glass frits showed high chemical durability, measured by the TCLP test. The crystallization of the glasses was evaluated by DTA. The crystal phases formed were identified by XRD resulting to be pyroxene and wollastonite solid solutions, magnetite and hematite. The morphology of the glass-ceramics was observed by optical and scanning electron microscopy. WSZ composition showed a high rate of bulk crystallization and resulted to be suitable for producing glass-ceramics by a short crystallization heat-treatment. WG composition showed a low crystallization rate and good sinterability; glass-ceramics were obtained by sinter-crystallization of the glass frit. PMID:17064848

  7. Modified ruthenium exchanged zeolites for enantioselective hydrogenation

    Microsoft Academic Search

    V. I. Pârvulescu; S. Coman; C. Radu; D. Macovei; Em Angelescu; R. Russu

    1995-01-01

    Preparation of modified ruthenium molecular sieves has been investigated in two steps-depositionof ruthenium and modifying of ruthenium molecular sieves in presence of ligands. As support sieve there were used two molecular sieves with large pore apertures and low acidity strength (zeolite L and APO-34). Correlation of in situ UV-VIS ruthenium deposition measurements with catalyst characterisation revealed that ruthenium deposition takes

  8. Copper and Copper Proteins in Parkinson's Disease

    PubMed Central

    Rivera-Mancia, Susana; Diaz-Ruiz, Araceli; Tristan-Lopez, Luis; Rios, Camilo

    2014-01-01

    Copper is a transition metal that has been linked to pathological and beneficial effects in neurodegenerative diseases. In Parkinson's disease, free copper is related to increased oxidative stress, alpha-synuclein oligomerization, and Lewy body formation. Decreased copper along with increased iron has been found in substantia nigra and caudate nucleus of Parkinson's disease patients. Copper influences iron content in the brain through ferroxidase ceruloplasmin activity; therefore decreased protein-bound copper in brain may enhance iron accumulation and the associated oxidative stress. The function of other copper-binding proteins such as Cu/Zn-SOD and metallothioneins is also beneficial to prevent neurodegeneration. Copper may regulate neurotransmission since it is released after neuronal stimulus and the metal is able to modulate the function of NMDA and GABA A receptors. Some of the proteins involved in copper transport are the transporters CTR1, ATP7A, and ATP7B and the chaperone ATOX1. There is limited information about the role of those biomolecules in the pathophysiology of Parkinson's disease; for instance, it is known that CTR1 is decreased in substantia nigra pars compacta in Parkinson's disease and that a mutation in ATP7B could be associated with Parkinson's disease. Regarding copper-related therapies, copper supplementation can represent a plausible alternative, while copper chelation may even aggravate the pathology. PMID:24672633

  9. Copper Data Center Database

    NSDL National Science Digital Library

    Copper Development Association

    The Copper Data Center Database is provided free of charge by the Copper Development Association "to increase knowledge and awareness of copper, related technologies, and the role of copper in the environment." The database is an online bibliographic search engine of literature on copper, copper alloys and copper technology dating back to 1965 and is described as covering copper technology from smelting and hydrometallurgy through the performance of copper and copper alloys in their end-use applications and service environments. Users can search by standard methods including using keywords and titles or an impressive advanced search feature is also available. Although full text listings are not available, anyone interested in related subjects will appreciate this well designed and unique tool.

  10. Innovation of a New-Style Macromolecule Compound Flocculant and its Application for Treating Copper Heavy Metal Wastewater

    Microsoft Academic Search

    Cui Yan; Wu Chao; Wang Haining; Feng Xiujuan

    2009-01-01

    The copper heavy metal wastewater does lots of harm to people and it is difficult to deal. Using flocculant to treat copper wastewater has a lot of advantages. Under certain conditions proceeded modification of a kind of clay which has the unique characteristic of absorbability. Then the modification clay and the polymerization iron carbonyl ion can play polyreaction, to innovate

  11. In Situ SAXS/WAXS of Zeolite Microwave Synthesis: NaY, NaA, and Beta Zeolites

    SciTech Connect

    Panzarella,B.; Tompsett, G.; Conner, W.; Jones, K.

    2007-01-01

    A custom waveguide apparatus is constructed to study the microwave synthesis of zeolites by in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The WR-284 waveguide is used to heat precursor solutions using microwaves at a frequency of 2.45 GHz. The reaction vessels are designed to include sections of thin-walled glass, which permit X-rays to pass through the precursor solutions with minimal attenuation. Slots were machined into the waveguide to provide windows for X-ray energy to enter and scatter from solutions during microwave heating. The synthesis of zeolites with conventional heating is also studied using X-ray scattering in the same reactor. SAXS studies show that the crystallization of beta zeolite and NaY zeolite is preceded by a reorganization of nanosized particles in their precursor solutions or gels. The evolution of these particles during the nucleation and crystallization stages of zeolite formation depends on the properties of the precursor solution. The synthesis of NaA and NaX zeolites and sodalite from a single zeolite precursor is studied by microwave and conventional heating. Microwave heating shifts the selectivity of this synthesis in favor of NaA and NaX over sodalite; conventional heating leads to the formation of sodalite for synthesis from the same precursor. The use of microwave heating also led to a more rapid onset of NaA zeolite product crystallization compared to conventional heating. Pulsed and continuous microwave heating are compared for zeolite synthesis. The resulting rates of formation of the zeolite products, and the relative amounts of the products determined from the WAXS spectra, are similar when either pulsed or continuous microwave heating is applied in the reactor while maintaining the same synthesis temperature. The consequences of these results in terms of zeolite synthesis are discussed.

  12. FUNDAMENTALS AND APPLICATIONS OF PERVAPORATION THROUGH ZEOLITE MEMBRANES

    EPA Science Inventory

    Zeolite membranes are well suited for separating liquid-phase mixtures by pervaporation because of their molecular-sized pores and their hydrophilic/hydrophobic nature, and the first commercial application of zeolite membranes has been for dehydrating organics [1]. Because of ...

  13. Crystal chemistry of the zeolites erionite and offretite

    Microsoft Academic Search

    E. PASSAGLIA; G. ARTIOLI; A. GUALTIERI

    Many known occurrences of the zeolites erionite and offretite have been characterized by electron probe microanalysis, X-ray powder diffraction, and optical microscopy. For the first time, a substantial amount of experimentally consistent and homogeneous chemical and crystallographic data have been evaluated for these natural zeolites. Systematic anal- ysis of the data, performed by statistical multivariate analysis, leads to the following

  14. Generation, Characterization, and Impact of Mesopores in Zeolite Catalysts

    Microsoft Academic Search

    Sander van Donk; Andries H. Janssen; Johannes H. Bitter; Krijn P. de Jong

    2003-01-01

    Amongst the current developments in the field of hierarchical pore structures, the creation of mesopores in zeolite crystals is the most frequently employed way to combine micropores with mesopores in one material. In this review an overview is presented of the different approaches to generate and characterize mesopores in zeolite crystals and establish their impact on the catalytic action. Mesopores

  15. Autocatalytic cure kinetics of natural zeolite filled epoxy composites

    Microsoft Academic Search

    Jae-Young Lee; Mi-Ja Shim; Sang-Wook Kim

    1997-01-01

    The effect of natural zeolite on the cure kinetics of epoxy resin system was studied by autocatalytic cure kinetics. In the thermograms obtained from dynamic analysis, the exothermic peak separated into two peaks by the addition of natural zeolite, and the exothermic peak temperatures and the reaction starting temperatures decreased. In the autocatalytic cure rate, the maximum cure rate appeared

  16. Effects of heating on salt-occluded zeolite

    SciTech Connect

    Lewis, M.A.; Hash, M.C.; Pereira, C.; Ackerman, J.P.

    1996-05-01

    The electrometallurgical treatment of spent nuclear fuel generates a waste stream of fission products in the electrolyte, LiCl-KCl eutectic salt. Argonne National Laboratory is developing a mineral waste form for this waste stream. The waste form consists of a composite formed by hot pressing salt-occluded zeolite and a glass binder. Pressing conditions must be judiciously chosen. For a given pressure, increasing temperatures and hold times give denser products but the zeolite is frequently converted to sodalite. Reducing the temperature or hold time leads to a porous zeolite composite. Therefore, conditions that affect the thermal stability of salt-occluded zeolite both with and without glass are being investigated in an ongoing study. The parameters varied in this stage of the work were heating time, temperature, salt loading, and glass content. The heat-treated samples were examined primarily by X-ray diffraction. Large variations were found in the rate at which salt-occluded zeolite converted to other phases such as nepheline, salt, and sodalite. The products depended on the initial salt loading. Heating times required for these transitions depended on the procedure and temperature used to prepare the salt-occluded zeolite. Mixtures of glass and zeolite reacted much faster than the pure salt-occluded zeolite and were almost always converted to sodalite.

  17. Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen

    DOEpatents

    Frei, H.; Blatter, F.; Sun, H.

    1999-06-22

    A process is described for selective thermal oxidation or photooxidation of hydrocarbons adsorbed onto zeolite matrices. A highly selective thermal oxidation and photooxidation of unsubstituted or alkyl substituted alkanes, alkenes, aromatics and cycloalkyls in solvent free zeolites under dark thermal conditions or under irradiation with visible light. The process oxidizes hydrocarbons almost completely selectively without substantial production of byproducts. 19 figs.

  18. Hydrogen atom addition to hydrocarbon guests in radiolyzed zeolites

    Microsoft Academic Search

    D. W. Werst; P. Han; S. C. Choure; E. I. Vinokur; L. Xu; A. D. Trifunac; L. A. Eriksson

    1999-01-01

    The formation of H adducts during radiolysis of zeolites containing olefinic and aromatic hydrocarbon guests was demonstrated to occur by H atom transfer from the zeolite to the adsorbed molecules. The H adducts and other paramagnetic radiolysis products (radical cations and H-loss radicals) were detected by EPR spectroscopy. The mechanism of H adduct formation was confirmed by, inter alia, H\\/D

  19. Middle distillate hydrotreatment zeolite catalysts containing Pt/Pd or Ni 

    E-print Network

    Marin-Rosas, Celia

    2009-05-15

    A study on middle distillate hydrotreatment zeolite catalysts containing Pt/Pd and/or Ni was performed. The effect of the addition of the corresponding CoMo, CoMoPd, CoMoPtPd and CoMoNi in PdNiPt-zeolite, Pt-zeolite, Ni-zeolite, and Pd...

  20. Density Functional Theory Study of Transformations of Nitrogen Oxides Catalyzed by Cu-Exchanged Zeolites

    E-print Network

    Adams, James B

    chemistry of nitrogen oxides. The catalyst active site is considered to be an isolated, zeolite (Z)-bound Cu zeolite catalyst chemistry. In a high silica zeolite such as Cu-ZSM-5, exchanged Cu is believed to exist-Exchanged Zeolites W. F. Schneider* and K. C. Hass Ford Research Laboratory, MD 3083/SRL, Dearborn, Michigan 48121

  1. An investigation of plant growth in an organo-zeolitic substrate and its ecological significance

    Microsoft Academic Search

    Peter J. Leggo

    2000-01-01

    This work concerns a series of experiments designed to test and understand the effect of ammoniated zeolite on plant growth. The affinity of the zeolite mineral clinoptilolite for NH4+ is utilised in organo-zeolitic substrates to enhance plant growth. By comparing plants grown in substrates with and without ammoniated zeolite, an increase in plant dry weight of some 19% was shown

  2. Formation of superacid centers in the structure of zeolite ZSM-5

    NASA Astrophysics Data System (ADS)

    Kitaev, L. E.; Kolesnikova, E. E.; Biryukova, E. N.; Kolesnichenko, N. V.; Khadzhiev, S. N.

    2013-04-01

    The structural changes and acid characteristics of the zeolite ZSM-5 modified with titanium and sulfur were studied. The modifier components were chemically bonded to the zeolite structure. The acid characteristics of zeolite changed and superacid centers appeared. A physicochemical study showed that treatment of zeolite with titanium tetrachloride and sulfuryl chloride did not change its structure and molecular-sieve properties.

  3. Amphiphilic organosilane-directed synthesis of crystalline zeolite with tunable mesoporosity

    Microsoft Academic Search

    Minkee Choi; Hae Sung Cho; Rajendra Srivastava; Chithravel Venkatesan; Dae-Heung Choi; Ryong Ryoo

    2006-01-01

    Zeolites are a family of crystalline aluminosilicate materials widely used as shape-selective catalysts, ion exchange materials, and adsorbents for organic compounds. In the present work, zeolites were synthesized by adding a rationally designed amphiphilic organosilane surfactant to conventional alkaline zeolite synthesis mixtures. The zeolite products were characterized by a complementary combination of X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy

  4. Surface metal ion enhancement of thermally treated zeolites

    SciTech Connect

    Willis, W.S.; Suib, S.L.

    1986-09-03

    During the past several years the area of zeolite science has received increasingly intense attention owing to the preparation of new molecular sieves and the availability of modern spectroscopic methods for the study of these materials. The majority of spectroscopic studies of zeolites have focused on measurements of bulk magnetic, electronic, and structural properties, but few surface studies have been reported. Surface-inhomogeneous aluminum and silicon species have recently been reported by Barr and co-workers. In this study the authors have heated metal ion containing zeolites under controlled conditions in order to probe interactions between the zeolite and the metal ion. Here they present preliminary results for Ag/sup +//NaY and Cs/sup +//NaY zeolites studied by X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SSIMS), and ion scattering spectroscopy (ISS).

  5. Influence of NaA Zeolite Crystal Expansion/Contraction on Zeolite Membrane Separations

    SciTech Connect

    Sorenson, Stephanie G [University of Colorado, Boulder; Payzant, E Andrew [ORNL; Gibbons, Will T [University of Colorado, Boulder; Soydas, Belma [University of Colorado, Boulder; Kita, Hidetoshi [Yamaguchi University, Japan; Noble, Richard D [University of Colorado, Boulder; Falconer, John L. [University of Colorado, Boulder

    2011-01-01

    In-situ powder XRD measurements showed that the NaA zeolite unit cell contracts and expands upon adsorption, and these changes in zeolite crystal size correlate with permeation changes through NaA zeolite membranes. These membranes had high pervaporation selectivities, even though gas permeation was mainly through defects, as indicated by Knudsen selectivities for gases. At 300 K and a thermodynamic activity of 0.03, water contracted the NaA crystals by 0.22 vol%, and this contraction increased the helium flux through two NaA membranes by approximately 80%. Crystal contraction also increased the fluxes of i-butane during vapor permeation and i-propanol (IPA) during pervaporation (~ 0.03 wt% water). At activities above 0.07, water expanded NaA crystals and correspondingly decreased the membrane fluxes of helium, i-butane, and IPA. Similarly, methanol contracted NaA crystals by 0.05 vol% at an activity of 0.02, and this contraction slightly increased the helium and i-butane fluxes through a NaA membrane. Above an activity of 0.06, methanol expanded the crystals, and the fluxes of helium and i-butane through a NaA membrane decreased. The adsorbate-induced changes explain some pervaporation behavior reported by others, and they indicate that crystal expansion and contraction may increase or decrease zeolite NaA membrane selectivity by changing the defect sizes.

  6. Carbon dioxide and methane transport in DDR zeolite: insights from molecular simulations into carbon dioxide separations in small pore zeolites

    Microsoft Academic Search

    Sang Eun Jee; David S. Sholl

    2009-01-01

    Zeolites are good candidates as a membranes for chemical separations because of their excellent chemical and thermal stability. Cage type zeolites are promising materials for gas separation since their narrow windows are expected to control molecular transport. DDR is one of the strongest candidates for light gas separations because of its narrow 8MR window. In our study, we examined the

  7. In-situ x-ray absorption study of copper films in ground watersolutions

    SciTech Connect

    Kvashnina, K.O.; Butorin, S.M.; Modin, A.; Soroka, I.; Marcellini, M.; Nordgren, J.; Guo, J.-H.; Werme, L.

    2007-10-29

    This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl{sup -} and HCO{sub 3}{sup -} in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM HCO{sub 3}{sup -} prevented or slowed down the corrosion processes.

  8. Carbon dioxide sensitivity of zeolitic imidazolate frameworks.

    PubMed

    Mottillo, Cristina; Friš?i?, Tomislav

    2014-07-14

    Zeolitic imidazolate frameworks of zinc, cobalt, and cadmium, including the framework ZIF-8 commercially sold as Basolite Z1200, exhibit surprising sensitivity to carbon dioxide under mild conditions. The frameworks chemically react with CO2 in the presence of moisture or liquid water to form carbonates. This effect, which has been previously not reported in metal-organic framework chemistry, provides an explanation for conflicting reports on ZIF-8 stability to water and is of outstanding significance for evaluating the potential applications of metal-organic frameworks, especially for CO2 sequestration. PMID:24889776

  9. Distribution of metal and adsorbed guest species in zeolites

    SciTech Connect

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  10. Synthesis, characterization and reactivity of transition-metal-containing zeolites

    SciTech Connect

    Rossin, J.A.

    1986-01-01

    Transition metal containing zeolites (zeolite A and ZSM-5) were prepared by addition of various transition metal containing substrates to zeolite synthesis gels. Crystal growth data were recorded in order to determine the influence of the transition metal species on the rate of crystal growth. X-ray diffraction, oxygen adsorption, FTIR and SEM were utilized to evaluate crystal purity. X-ray photoelectron spectroscopy (XPS), chemical analysis and electron microprobe analysis were performed in order to ascertain the position (intrazeolitic versus surface) and homogeneity of the transition metal. It was concluded that intrazeolitic transition metals are produced by the novel procedure presented in this work. 1-Hexane hydroformylation by rhodium zeolite A showed intrazeolitic rhodium to migrate to the external surface of the zeolite. However, in the presence of a solution and surface rhodium poison, intrazeolitic rhodium was found to hydroformylate 1-hexene exclusively to heptanal. Ruthenium containing zeolite A was evaluated under CO-hydrogenation conditions. No migration of intrazeolitic ruthenium to the external surface of the zeolite was observed over the course of the reaction. The product distribution obtained for this catalyst did not follow a log normal behavior. Also, loss of zeolite crystallinity was observed following the reaction. Cobalt ZSM-5 was evaluated under CO-hydrogenation conditions. No migration of cobalt to the external surface of the zeolite occurred. XPS analysis of the catalyst following various stages of the reaction indicated that intrazeolitic cobalt was not reduced to the zero valent state. Consequently, the non-zero valent cobalt was not capable of hydrogenating carbon monoxide.

  11. Gold nanoclusters confined in a supercage of Y zeolite for aerobic oxidation of HMF under mild conditions.

    PubMed

    Cai, Jiaying; Ma, Hong; Zhang, Junjie; Song, Qi; Du, Zhongtian; Huang, Yizheng; Xu, Jie

    2013-10-11

    Au nanoclusters with an average size of approximately 1?nm size supported on HY zeolite exhibit a superior catalytic performance for the selective oxidation of 5-hydroxymethyl-2-furfural (HMF) into 2,5-furandicarboxylic acid (FDCA). It achieved >99?% yield of 2,5-furandicarboxylic acid in water under mild conditions (60?°C, 0.3?MPa oxygen), which is much higher than that of Au supported on metal oxides/hydroxide (TiO2 , CeO2 , and Mg(OH)2 ) and channel-type zeolites (ZSM-5 and H-MOR). Detailed characterizations, such as X-ray diffraction, transmission electron microscopy, N2 -physisorption, and H2 -temperature-programmed reduction (TPR), revealed that the Au nanoclusters are well encapsulated in the HY zeolite supercage, which is considered to restrict and avoid further growing of the Au nanoclusters into large particles. The acidic hydroxyl groups of the supercage were proven to be responsible for the formation and stabilization of the gold nanoclusters. Moreover, the interaction between the hydroxyl groups in the supercage and the Au nanoclusters leads to electronic modification of the Au nanoparticles, which is supposed to contribute to the high efficiency in the catalytic oxidation of HMF to FDCA. PMID:23999985

  12. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A. (Ames, IA); Verhoeven, John D. (Ames, IA); Gibson, Edwin D. (Ames, IA)

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  13. Copper associated childhood cirrhosis

    Microsoft Academic Search

    S P Horslen; M S Tanner; T D Lyon; G S Fell; M F Lowry

    1994-01-01

    Several papers have reported severe liver disease in association with massive hepatic copper accumulation, which do not seem to be either of the recognised copper associated liver diseases, namely Wilson's disease and Indian childhood cirrhosis. A further case is reported in which novel copper kinetic studies were carried out using the stable isotope 65Cu, showing that this patient did not

  14. Laser induced copper plating

    Microsoft Academic Search

    A. K. Al-Sufi; H. J. Eichler; J. Salk; H. J. Riedel

    1983-01-01

    Argon laser induced plating of copper spots and lines from copper sulfate solutions on glass and phenolic resin paper has been investigated. The substrates had to be precoated with an evaporated copper film. The highest plating rates have been obtained with a small film thickness of 25 nm. Spots with a thickness up to 30 ?m were plated.

  15. Hierarchical zeolites from class F coal fly ash

    NASA Astrophysics Data System (ADS)

    Chitta, Pallavi

    Fly ash, a coal combustion byproduct is classified as types class C and class F. Class C fly ash is traditionally recycled for concrete applications and Class F fly ash often disposed in landfills. Class F poses an environmental hazard due to disposal and leaching of heavy metals into ground water and is important to be recycled in order to mitigate the environmental challenges. A major recycling option is to reuse the fly ash as a low-cost raw material for the production of crystalline zeolites, which serve as catalysts, detergents and adsorbents in the chemical industry. Most of the prior literature of fly ash conversion to zeolites does not focus on creating high zeolite surface area zeolites specifically with hierarchical pore structure, which are very important properties in developing a heterogeneous catalyst for catalysis applications. This research work aids in the development of an economical process for the synthesis of high surface area hierarchical zeolites from class F coal fly ash. In this work, synthesis of zeolites from fly ash using classic hydrothermal treatment approach and fusion pretreatment approach were examined. The fusion pretreatment method led to higher extent of dissolution of silica from quartz and mullite phases, which in turn led to higher surface area and pore size of the zeolite. A qualitative kinetic model developed here attributes the difference in silica content to Si/Al ratio of the beginning fraction of fly ash. At near ambient crystallization temperatures and longer crystallization times, the zeolite formed is a hierarchical faujasite with high surface area of at least 360 m2/g. This work enables the large scale recycling of class F coal fly ash to produce zeolites and mitigate environmental concerns. Design of experiments was used to predict surface area and pore sizes of zeolites - thus obviating the need for intense experimentation. The hierarchical zeolite catalyst supports tested for CO2 conversion, yielded hydrocarbons up to C9, a performance attesting the hierarchal pore structure. The preliminary techno-economic feasibility assessment demonstrates a net energy saving of 75% and cost saving of 63% compared to the commercial zeolite manufacturing process.

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

    SciTech Connect

    Garbowski, E.D.; Mirodatos, C.

    1982-01-07

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

  17. Method of preparing sodalite from chloride salt occluded zeolite

    DOEpatents

    Lewis, M.A.; Pereira, C.

    1997-03-18

    A method is described for immobilizing waste chloride salts containing radionuclides and hazardous nuclear material for permanent disposal starting with a substantially dry zeolite and sufficient glass to form leach resistant sodalite with occluded radionuclides and hazardous nuclear material. The zeolite and glass are heated to a temperature up to about 1000 K to convert the zeolite to sodalite and thereafter maintained at a pressure and temperature sufficient to form a sodalite product near theoretical density. Pressure is used on the formed sodalite to produce the required density.

  18. Method of preparing sodalite from chloride salt occluded zeolite

    DOEpatents

    Lewis, Michele A. (Naperville, IL); Pereira, Candido (Lisle, IL)

    1997-01-01

    A method for immobilizing waste chloride salts containing radionuclides and hazardous nuclear material for permanent disposal starting with a substantially dry zeolite and sufficient glass to form leach resistant sodalite with occluded radionuclides and hazardous nuclear material. The zeolite and glass are heated to a temperature up to about 1000.degree. K. to convert the zeolite to sodalite and thereafter maintained at a pressure and temperature sufficient to form a sodalite product near theoretical density. Pressure is used on the formed sodalite to produce the required density.

  19. Method of preparing sodalite from chloride salt occluded zeolite A

    SciTech Connect

    Lewis, M.A.; Pereira, C.

    1995-12-31

    A method is described for immobilizing waste chloride salts containing radionuclides and hazardous nuclear material for permanent disposal starting with a substantially dry zeolite and sufficient glass to form leach resistance sodalite with occluded radionuclides and hazardous nuclear material. The zeolite and glass are heated to a temperature up to about 1,000 K to convert the zeolite to sodalite and thereafter maintained at a pressure and temperature sufficient to form a sodalite product near theoretical density. Pressure is used on the formed sodalite to produce the required density.

  20. Catalytic pyrolysis using UZM-44 aluminosilicate zeolite

    DOEpatents

    Nicholas, Christopher P; Boldingh, Edwin P

    2014-04-29

    A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  1. Alkaline hydrothermal conversion of fly ash filtrates into zeolites 2: utilization in wastewater treatment.

    PubMed

    Somerset, Vernon; Petrik, Leslie; Iwuoha, Emmanuel

    2005-01-01

    Filtrates were collected using a codisposal reaction wherein fly ash was reacted with acid mine drainage. These codisposal filtrates were then analyzed by X-ray Fluorescence spectrometry for quantitative determination of the SiO2 and Al2O3 content. Alkaline hydrothermal zeolite synthesis was then applied to the filtrates to convert the fly ash material into zeolites. The zeolites formed under the experimental conditions were faujasite, sodalite, and zeolite A. The use of the fly ash-derived zeolites and a commercial zeolite was explored in wastewater decontamination experiments as it was applied to acid mine drainage in different dosages. The concentrations of Ni, Zn, Cd, As, and Pb metal ions in the treated wastewater were investigated. The results of the treatment of the acid mine drainage with the prepared fly ash zeolites showed that the concentrations of Ni, Zn, Cd, and Hg were decreased as the zeolite dosages of the fly ash zeolite (FAZ1) increased. PMID:15991728

  2. Hydrophobic high surface area zeolites derived from fly ash for oil spill remediation.

    PubMed

    Sakthivel, Tamilselvan; Reid, David L; Goldstein, Ian; Hench, Larry; Seal, Sudipta

    2013-06-01

    Fly ash, a coal combustion byproduct with a predominantly aluminosilicate composition, is modified to develop an inexpensive sorbent for oil spill remediation. The as-produced fly ash is a hydrophilic material with poor sorption capacity. A simple two-step chemical modification process is designed to improve the oil sorption capacity. First, the fly ash was transformed to a zeolitic material via an alkali treatment, which increased the specific surface area up to 404 m(2) g(-1). Then, the material was surface functionalized to form a hydrophobic material with high contact angle up to 147° that floats on the surface of an oil-water mixture. The reported oil sorption capacities of X-type zeolite sorbent with different surface functionalization (propyl-, octyl-, octadecyl-trimethoxysilane and esterification) were estimated to 1.10, 1.02, 0.86, and 1.15 g g(-1), respectively. Oil sorption was about five times higher than the as-received fly ash (0.19 g g(-1)) and also had high buoyancy critical for economic cleanup of oil over water. PMID:23634731

  3. Design of composite photocatalyst of TiO2 and Y-zeolite for degradation of 2-propanol in the gas phase under UV and visible light irradiation.

    PubMed

    Kamegawa, Takashi; Ishiguro, Yasushi; Kido, Ryota; Yamashita, Hiromi

    2014-01-01

    Hydrophobic Y-zeolite (SiO2/Al2O3 = 810) and TiO2 composite photocatalysts were designed by using two different types of TiO2 precursors, i.e., titanium ammonium oxalate and ammonium hexafluorotitanate. The porous structure, surface property and state of TiO2 were investigated by various characterization techniques. By using an ammonium hexafluorotitanate as a precursor, hydrophobic modification of the Y-zeolite surface and realizing visible light sensitivity was successfully achieved at the same time after calcination at 773 K in the air. The prepared sample still maintained the porous structure of Y-zeolite and a large surface area. Highly crystalline anatase TiO2 was also formed on the Y-zeolite surface by the role of fluorine in the precursor. The usages of ammonium hexafluorotitanate were effective for the improvement of the photocatalytic performance of the composite in the degradation of 2-propanol in the gas phase under UV and visible light (? > 420 nm) irradiation. PMID:25314607

  4. Fine route for an efficient removal of 2,4-dichlorophenoxyacetic acid (2,4-D) by zeolite-supported TiO2.

    PubMed

    Shankar, M V; Anandan, S; Venkatachalam, N; Arabindoo, B; Murugesan, V

    2006-05-01

    Zeolites HY, Hbeta and HZSM-5 with different physico-chemical properties were chosen as support for TiO2 to illustrate their adsorption, dispersion and electronic structure in photocatalysis. The extent of TiO2 loading was monitored by XRD and BET surface area measurements. The adsorption capacity of HY zeolite was found to be high and hence chosen for further modification to continue the investigation. Photodegradation kinetics were carried out with 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution. The extent of 2,4-D degradation on TiO2/HY loading revealed the importance of adsorption in photocatalysis. Mineralisation studies on all three zeolites with 1 wt.% TiO2 loading demonstrated the good dispersion properties of TiO2/HY. Its photocatalytic activity was found to be excellent with formulated 2,4-D. Comparison of relative photonic efficiencies demonstrated that supported photocatalysts exhibited higher activity than some of the commercial photocatalysts. The high activity of supported TiO2 is due to synergistic effects of improved adsorption of 2,4-D and efficient delocalisation of photogenerated electrons by zeolite support. PMID:16289243

  5. Uniformly microsized luminescent materials obtained through a solid state reaction of WO{sub 3} with Ln{sup 3+}-exchanged zeolite L at 700 °C

    SciTech Connect

    Wang, Yige, E-mail: wangyige@hebut.edu.cn [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Fang, Yi; Zhang, Wenjun; Zhang, Li; Chen, Yuhuan; Yu, Xiaoyan [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China)

    2013-06-01

    Graphical abstract: We have reported the modification of Ln3+/ZL microcrystals by the tungstate-oxygen species via a solid state reaction of WO{sub 3} and Ln{sup 3+}-exchanged zeolite L at 700 °C. Highlights: ? Luminescent materials were obtained from zeolite L crystals. ? The materials show characteristic luminescence of Eu{sup 3+} and Tb{sup 3+} ions. ? The framework of zeolite L crystals has been kept during the annealing process. ? Energy transfer from tungstate-oxygen species to lanthanide was confirmed. - Abstract: In this work, we report the uniformly microsized luminescent materials prepared by a solid state reaction of WO{sub 3} and Ln{sup 3+}-exchanged zeolite L at 700 °C. The obtained materials were investigated by SEM, XRD and photoluminescence spectroscopy. The influence of tungstate-oxygen species on the morphology and luminescence of the materials were discussed in detail. Energy transfer from the tungstate-oxygen species to Eu{sup 3+} and Tb{sup 3+} ions have been demonstrated by the photoluminescence spectra, implying the loading of tungstate-oxygen species into the nanochannels of the crystals and the close proximity of which to Eu{sup 3+} ions.

  6. Characterization and impact of reduced copper plating overburden on 45 nm interconnect performances

    Microsoft Academic Search

    O. Dubreuil; V. Caubet-Hilloutou; J. Guillan; K. Haxaire; M. Mellier; P. Caubet; P. Vannier; E. Petitprez; D. Bellet; Ph. Normandon

    2010-01-01

    During first metal level interconnects fabrication, a controlled modification of the electro-deposited copper over-deposition (overburden) is performed using a partial chemical–mechanical polishing (CMP) step. Next, copper microstructure is stabilized with a short duration hot-plate anneal. Overburden is then removed during CMP end-of-step. Ionic microscopy and EBSD observations of overburden thickness reduction reveal that copper grain growth occurs differently, according to

  7. Alkylcarbenium Ion Concentrations in Zeolite Pores During Octane Hydrocracking on Pt\\/H-USY Zeolite

    Microsoft Academic Search

    Joris W. Thybaut; C. S. Laxmi Narasimhan; Guy B. Marin; Joeri F. M. Denayer; Gino V. Baron; Pierre A. Jacobs; Johan A. Martens

    2004-01-01

    Hydroconversion of octane over platinum loaded acid zeolites was simulated using a single-event microkinetic model. Significantly different values for the alkene standard protonation enthalpies, i.e., -59.2 and –94 kJ mol-1 for the charging of secondary and tertiary carbon atoms respectively, were obtained. This difference is in favor of a carbocationic nature of the reactive intermediates on the acid sites rather

  8. Interaction between zeolites and cluster compounds. Part 2.?Thermal decomposition of iron pentacarbonyl on zeolites

    Microsoft Academic Search

    Thomas Bein; Peter A. Jacobs

    1984-01-01

    Thermal decomposition in a thermobalance of Fe(CO), adsorbed on alkali-metal, hydrogen-Y, dealuminated Y, L and omega zeolites proceeds stepwise via slow decarbonylation at low and high temperatures, separated by a fast endothermic reaction. Average CO\\/Fe ratios have been determined after each step. From i.r. results the former intermediates are assigned to species bearing bridging CO, whereas reaction products with CO\\/Fe

  9. Xenon NMR studies of dynamics and exchange in zeolites

    SciTech Connect

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

    1996-10-01

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

  10. 12. INTERIOR OF BUILDING 2, ORIGINAL ZEOLITE PLANT, AT WEYMOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. INTERIOR OF BUILDING 2, ORIGINAL ZEOLITE PLANT, AT WEYMOUTH LOOKING WEST TO FOUNTAIN. STAIRWAY RUNS DOWN TO FILTRATION BAYS. - F. E. Weymouth Filtration Plant, 700 North Moreno Avenue, La Verne, Los Angeles County, CA

  11. Single and Multiple Heteroatom Incorporation in MFI Zeolites 

    E-print Network

    Garcia Vargas, Nataly

    2012-11-05

    realistic scenarios for industrial implementation. The main objective of this dissertation was to study the single and simultaneous framework incorporation of tin, boron, germanium and aluminum in MFI zeolites under synthesis conditions that are more...

  12. High-silica zeolite nucleation from clear solutions

    E-print Network

    Cheng, Chil-Hung

    2006-04-12

    . This work initially tried to apply the insights developed from the TPAsilicalite- 1 clear solution synthesis by investigating the nanoparticles formation and zeolite growth in several tetraethyl orthosilicate (TEOS)-organocation-water solutions heated at 368...

  13. Investigation of Zeolite Nucleation and Growth Using NMR Spectroscopy 

    E-print Network

    Rivas Cardona, Alejandra

    2012-02-14

    and control of the zeolite properties. The primary objective of this dissertation is to determine the strength of organicinorganic interactions (i.e., the adsorption Gibbs energy) in transparent synthesis mixtures using PFG NMR spectroscopy, in order...

  14. Hydrogen Adsorption in Zeolite Studied with Sievert and Thermogravimetric Methods

    NASA Astrophysics Data System (ADS)

    Lesnicenoks, P.; Sivars, A.; Grinberga, L.; Kleperis, J.

    2012-08-01

    Natural clinoptilolite (mixture from clinoptilolite, quartz and muscovite) is activated with palladium and tested for hydrogen adsorption capability at temperatures RT - 200°C. Thermogravimetric and volumetric methods showed that zeolite activated with palladium (1.25%wt) shows markedly high hydrogen adsorption capacity - up to 3 wt%. Lower amount of adsorbed hydrogen (~1.5 wt%) was found for raw zeolite and activated with higher amount of palladium sample. Hypothesis is proposed that the heating of zeolite in argon atmosphere forms and activates the pore structure in zeolite material, where hydrogen encapsulation (trapping) is believed to occur when cooling down to room temperature. An effect of catalyst (Pd) on hydrogen sorption capability is explained by spillover phenomena were less-porous fractions of natural clinoptilolite sample (quartz and muscovite) are involved.

  15. High-silica zeolite nucleation from clear solutions 

    E-print Network

    Cheng, Chil-Hung

    2006-04-12

    . This work initially tried to apply the insights developed from the TPAsilicalite- 1 clear solution synthesis by investigating the nanoparticles formation and zeolite growth in several tetraethyl orthosilicate (TEOS)-organocation-water solutions heated at 368...

  16. Theoretical models for NO decomposition in Cu-exchanged zeolites

    E-print Network

    Tsekov, R

    2015-01-01

    A unified description of the catalytic effect of Cu-exchanged zeolites is proposed for the decomposition of NO. A general expression for the rate constant of NO decomposition is obtained by assuming that the rate-determining step consists of the transferring of a single atom associated with breaking of the N-O bond. The analysis is performed on the base of the generalized Langevin equation and takes into account both the potential interactions in the system and the memory effects due to the zeolite vibrations. Two different mechanisms corresponding to monomolecular and bimolecular NO decomposition are discussed. The catalytic effect in the monomolecular mechanism is related to both the Cu+ ions and zeolite O-vacancies, while in the case of the bimolecular mechanism the zeolite contributes through dissipation only. The comparison of the theoretically calculated rate constants with experimental results reveals additional information about the geometric and energetic characteristics of the active centers and con...

  17. Adsorption of trichlorophenol on zeolite and adsorbent regeneration with ozone.

    PubMed

    Zhang, Yongjun; Mancke, Raoul Georg; Sabelfeld, Marina; Geißen, Sven-Uwe

    2014-04-30

    A FAU-type zeolite was studied as an adsorbent to remove 2,4,6-trichlorophenol (TCP), a frequently detected recalcitrant pollutant in water bodies. Both adsorption isotherm and kinetics were studied with TCP concentrations from 10 to 100mg/L. It was observed that TCP was effectively adsorbed onto the zeolite with a high adsorption capacity and a high kinetic rate. Freundlich model and pseudo-second-order kinetics were successfully applied to describe the experimental data. The influence of solution pH was also studied. Furthermore, ozone was applied to regenerate the loaded zeolite. It was found that an effective adsorption of TCP was kept for at least 8 cycles of adsorption and regeneration. The ozonation also increased the BET specific surface of zeolite by over 60% and consequently enhanced the adsorption capacity. PMID:24632370

  18. Structured carbon adsorbents from clay, zeolite and mesoporous aluminosilicate templates

    Microsoft Academic Search

    P. M Barata-Rodrigues; T. J Mays; G. D Moggridge

    2003-01-01

    Porous carbons templated from inorganic materials such as zeolites and mesoporous molecular sieves received considerable attention in the last decade. In this context, we discuss the effects of different templating structures on the carbons yielded. We describe templating using a commercial cationic clay (Wyoming bentonite), a commercial zeolite (Tosoh H-Beta) and a synthetic mesoporous aluminosilicate (Al-MCM-48), as exemplars of the

  19. Removal of dilute benzene using zeolite-hybrid plasma reactor

    Microsoft Academic Search

    Atsushi OGATA; Daisuke Ito; Koichi MIZUNO; Satoshi KUSHIYAMA; Toshiaki YAMAMOTO

    1999-01-01

    The decomposition of benzene was carried out using a plasma reactor packed with a mixture of BaTiO3 and zeolite pellets, the zeolite-hybrid reactor. The reactor performance was characterized by measuring COx formed during plasma discharge and COx adsorbed on the solid surface. The decomposition efficiency of benzene in the hybrid reactor was 1.4 to 2.1 times higher than that in

  20. Simulating Microwave-Heated Diffusion in Zeolite Nanopores

    Microsoft Academic Search

    Cristian Blanco; Scott M. Auerbach

    We have performed equilibrium molecular dynamics and microwave (MW) heated molecular dynamics simulations to explore how MW heating influences self-diffusion in zeolite nanopores. We have applied these simulations to methanol and\\/or benzene in de-aluminated Y zeolite. We have found that even under the non-equilibrium conditions of MW heating, center-of-mass motions can be associated with effective temperatures. However, we find that

  1. The safety of synthetic zeolites used in detergents

    Microsoft Academic Search

    Claudia Fruijtier-Pölloth

    2009-01-01

    Synthetic zeolites are replacing phosphates as builders in laundry detergents; workers and consumers may, therefore, increasingly\\u000a be exposed to these materials and it is important to assess their safety. This article puts mechanistic, toxicological and\\u000a exposure data into context for a safety assessment. Zeolites are hygroscopic compounds with ion-exchanging properties. They\\u000a may partially decompose under acidic conditions such as in

  2. Tribomechanical micronization and activation of whey protein concentrate and zeolite

    Microsoft Academic Search

    Z. Herceg; V. Lelas; M. Brn?i?; B. Tripalo; D. Jezek

    2004-01-01

    Tribomechanics is a part of physics that is concerned with the study of phenomena that appear during milling under dynamic\\u000a conditions. Tribomechanical micronization and activation (TMA) of whey protein concentrates (WPC) and zeolites (type clinoptilolite)\\u000a were carried out. Samples of powdered WPC and zeolite were treated with the laboratory TMA equipment. The treatment was carried\\u000a out at two various rotor

  3. Synthesis and characterization of an offretite\\/erionite type zeolite

    Microsoft Academic Search

    Sanyuan Yang; N. P. Evmiridis

    1996-01-01

    A novel method is described for the preparation of offretite\\/erionite type zeolites without use of nitrogen-containing templates. It is based on the introduction of a certain amount of potassium ions into a synthesis system leading to the formation of an omega type zeolite. The synthesized product is characterized by X-ray diffraction and scanning electron microscopy and is identified as a

  4. Transport of C 6 isomers through ZSM-5 zeolite membranes

    Microsoft Academic Search

    Stefan Sommer; Thomas Melin; John L. Falconer; Richard D. Noble

    2003-01-01

    The separation of binary mixtures of hexane isomers using ZSM-5 zeolite membranes on porous stainless steel and alumina tubes was modeled for both vapor permeation and pervaporation. The fluxes and selectivities for single-component and mixture permeation of n-hexane, 3-methylpentane (3-MP), and 2,2-dimethylbutane (DMB) were described by combining two diffusion mechanisms. The flux through zeolite pores was modeled by Maxwell–Stefan diffusion

  5. High resolution argon adsorption isotherms for various zeolites

    Microsoft Academic Search

    K. Nakai; J. Sonoda; M. Yoshida; M. Hakuman; H. Naono

    2007-01-01

    Ar isotherms (87.3 K) and N2 isotherms (77.4 K) were measured for two silicas with different silanol content and two MFI zeolites with different alumina (proton) content. Silanols or protons give the significant effect on 2 isotherms, but has little influence on Ar isotherms. Ar isotherms for seven zeolites of various micropore size were measured in the pressure range of

  6. Pd–Zeolites as Heterogeneous Catalysts in Heck Chemistry

    Microsoft Academic Search

    M. Dams; L. Drijkoningen; B. Pauwels; G. Van Tendeloo; D. E. De Vos; P. A. Jacobs

    2002-01-01

    Heck reactions were performed with 4-bromoacetophenone and n-butyl acrylate, yielding the trans-arylated acrylate ester with high selectivity. Pd–zeolite catalysts were compared with supported Pd metal catalysts. In order to obtain an active and heterogeneous catalyst, the preformed or in situ-formed catalytically active Pd0 species and the PdII intermediates must be sufficiently stabilized on the zeolites against leaching and against aggregation

  7. Cadmium adsorption on vermiculite, zeolite and pumice: Batch experimental studies

    Microsoft Academic Search

    Maria Rosaria Panuccio; Agostino Sorgonà; Marcella Rizzo; Giovanni Cacco

    2009-01-01

    Batch experiments were performed to evaluate the combined effects of ionic activity, pH, and contact time on the cadmium sorption in three different minerals, vermiculite, zeolite, and pumice, commonly employed as substrata in nurseries and recently considered for their potential use in remediation methods. The extent of cadmium sorption was vermiculite>zeolite>pumice, as shown by the Langmuir and Freundlich parameters, and

  8. Lightweight and Thermal Blocks from Zeolites as Aggregated

    Microsoft Academic Search

    G. T. Munive; A. L. Leal-Cruz; M. I. Pech-Canul; J. A. Rodríguez-García; E. Rocha-Rangel

    2011-01-01

    The present research is focused on the design of mixtures containing zeolite (Z), as an alternative aggregate and their use in the production of blocks with lightweight and insulating properties that comply with the specific requirements of standards for its application in construction. To improve lightweight and insulating properties in blocks, first mixtures zeolitic sand-cement-lime (ZS\\/C\\/L) were prepared and their

  9. COPPER DEFICIENCY PROPHYLAXIS IN GRAZING SHEEP BY COPPER OXIDE INJECTION

    E-print Network

    Boyer, Edmond

    COPPER DEFICIENCY PROPHYLAXIS IN GRAZING SHEEP BY COPPER OXIDE INJECTION M. LAMAND Claudine LAB R of insoluble and non ionized form of injected copper has been shown in a previous paper (Lamand, 1978 it appeared that copper oxide was preferable to metallic copper, being slightly less caustic. Inflammation

  10. Moderate-temperature zeolitic alteration in a cooling pyroclastic deposit

    USGS Publications Warehouse

    Levy, S.S.; O'Neil, J.R.

    1989-01-01

    The locally zeolitized Topopah Spring Member of the Paintbrush Tuff (13 Myr.), Yucca Mountain, Nevada, U.S.A., is part of a thick sequence of zeolitized pyroclastic units. Most of the zeolitized units are nonwelded tuffs that were altered during low-temperature diagenesis, but the distribution and textural setting of zeolite (heulandite-clinoptilolite) and smectite in the densely welded Topopah Spring tuff suggest that these hydrous minerals formed while the tuff was still cooling after pyroclastic emplacement and welding. The hydrous minerals are concentrated within a transition zone between devitrified tuff in the central part of the unit and underlying vitrophyre. Movement of liquid and convected heat along fractures from the devitrified tuff to the ritrophyre caused local devitrification and hydrous mineral crystallization. Oxygen isotope geothermometry of cogenetic quartz confirms the nondiagenetic moderate temperature origin of the hydrous minerals at temperatures of ??? 40-100??C, assuming a meteoric water source. The Topopah Spring tuff is under consideration for emplacement of a high-level nuclear waste repository. The natural rock alteration of the cooling pyroclastic deposit may be a good natural analog for repository-induced hydrothermal alteration. As a result of repository thermal loading, temperatures in the Topopah Spring vitrophyre may rise sufficiently to duplicate the inferred temperatures of natural zeolitic alteration. Heated water moving downward from the repository into the vitrophyre may contribute to new zeolitic alteration. ?? 1989.

  11. Nanosized zeolites as a perspective material for conductometric biosensors creation

    NASA Astrophysics Data System (ADS)

    Kucherenko, Ivan; Soldatkin, Oleksandr; Kasap, Berna Ozansoy; Kirdeciler, Salih Kaan; Kurc, Burcu Akata; Jaffrezic-Renault, Nicole; Soldatkin, Alexei; Lagarde, Florence; Dzyadevych, Sergei

    2015-05-01

    In this work, the method of enzyme adsorption on different zeolites and mesoporous silica spheres (MSS) was investigated for the creation of conductometric biosensors. The conductometric transducers consisted of gold interdigitated electrodes were placed on the ceramic support. The transducers were modified with zeolites and MSS, and then the enzymes were adsorbed on the transducer surface. Different methods of zeolite attachment to the transducer surface were used; drop coating with heating to 200°C turned out to be the best one. Nanozeolites beta and L, zeolite L, MSS, and silicalite-1 (80 to 450 nm) were tested as the adsorbents for enzyme urease. The biosensors with all tested particles except zeolite L had good analytical characteristics. Silicalite-1 (450 nm) was also used for adsorption of glucose oxidase, acetylcholinesterase, and butyrylcholinesterase. The glucose and acetylcholine biosensors were successfully created, whereas butyrylcholinesterase was not adsorbed on silicalite-1. The enzyme adsorption on zeolites and MSS is simple, quick, well reproducible, does not require use of toxic compounds, and therefore can be recommended for the development of biosensors when these advantages are especially important.

  12. Nanocellulose-Zeolite Composite Films for Odor Elimination.

    PubMed

    Keshavarzi, Neda; Mashayekhy Rad, Farshid; Mace, Amber; Ansari, Farhan; Akhtar, Farid; Nilsson, Ulrika; Berglund, Lars; Bergström, Lennart

    2015-07-01

    Free standing and strong odor-removing composite films of cellulose nanofibrils (CNF) with a high content of nanoporous zeolite adsorbents have been colloidally processed. Thermogravimetric desorption analysis (TGA) and infrared spectroscopy combined with computational simulations showed that commercially available silicalite-1 and ZSM-5 have a high affinity and uptake of volatile odors like ethanethiol and propanethiol, also in the presence of water. The simulations showed that propanethiol has a higher affinity, up to 16%, to the two zeolites compared with ethanethiol. Highly flexible and strong free-standing zeolite-CNF films with an adsorbent loading of 89 w/w% have been produced by Ca-induced gelation and vacuum filtration. The CNF-network controls the strength of the composite films and 100 ?m thick zeolite-CNF films with a CNF content of less than 10 vol % displayed a tensile strength approaching 10 MPa. Headspace solid phase microextraction (SPME) coupled to gas chromatography-mass spectroscopy (GC/MS) analysis showed that the CNF-zeolite films can eliminate the volatile thiol-based odors to concentrations below the detection ability of the human olfactory system. Odor removing zeolite-cellulose nanofibril films could enable improved transport and storage of fruits and vegetables rich in odors, for example, onion and the tasty but foul-smelling South-East Asian Durian fruit. PMID:26061093

  13. Asymmetric printing of molecules and zeolites on self assembled monolayers

    NASA Astrophysics Data System (ADS)

    Kehr, Nermin Seda; Schäfer, Andreas; Ravoo, Bart Jan; de Cola, Luisa

    2010-04-01

    Microcontact printing (mCP) is used to immobilize dyes and peptides asymmetrically, by a ``peptide coupling'' reaction, on monolayers of zeolite L crystals in the contact area between the stamp and the surface of the monolayer. Chemically patterned surfaces of monolayers of zeolite L crystals are obtained by using patterned stamps with different ink solutions. Additional printing of functionalized nano-objects on SAMs of zeolite L crystals is demonstrated.Microcontact printing (mCP) is used to immobilize dyes and peptides asymmetrically, by a ``peptide coupling'' reaction, on monolayers of zeolite L crystals in the contact area between the stamp and the surface of the monolayer. Chemically patterned surfaces of monolayers of zeolite L crystals are obtained by using patterned stamps with different ink solutions. Additional printing of functionalized nano-objects on SAMs of zeolite L crystals is demonstrated. Electronic supplementary information (ESI) available: Details of XPS spectra are given. See DOI: 10.1039/b9nr00285e

  14. Solvent Evaporation Assisted Preparation of Oriented Nanocrystalline Mesoporous MFI Zeolites

    SciTech Connect

    Zhu, Kake; Sun, Junming; Liu, Jun; Wang, Li Q.; Wan, Haiying; Hu, Jian Z.; Wang, Yong; Peden, Charles HF; Nie, Zimin

    2011-07-01

    A solvent evaporation route to produce hierarchically porous zeolites with an oriented MFI nanocrystalline structure has been developed, and the method is scalable and productive. In this method, hexadecyltrimethoxysilane is added to an ethanol solution containing zeolitic precursors. A hard gel is formed during the evaporation process. Subsequent hydrothermal treatments produce the hierarchically porous zeolite. High resolution transmission electron microscopy (HRTEM) studies suggest that misoriented zeolite nuclei are produced in the very early stages of the hydrothermal treatment, but further reactions lead to single crystal-like aggregates composed of intergrowth nanocrystals with a mean interparticle pore diameter of 12 nm. All Al atoms exist in tetrahedral sites, as confirmed by 27Al magic angle spinning nuclear magnetic resonance (MAS NMR). Variable temperature hyperpolarized (HP) 129Xe NMR spectroscopy suggest a fast molecular diffusion process from the interconnection between micro- and mesopores. Catalytic conversion of acetone to the isobutene reactions show comparable (with respect to conventional zeolites) selectivity to isobutene. However, hierarchically porous zeolites display enhanced activity and durability because of the more accessible acidic sites in the hierarchically porous structures.

  15. Following the movement of Cu ions in a SSZ-13 zeolite during dehydration, reduction and adsorption: a combined in situ TP-XRD, XANES/DRIFTS study

    SciTech Connect

    Kwak, Ja Hun; Varga, Tamas; Peden, Charles HF; Gao, Feng; Hanson, Jonathan C.; Szanyi, Janos

    2014-05-05

    Cu-SSZ-13 has been shown to possess high activity and superior N2 formation selectivity in the selective catalytic reduction of NOx under oxygen rich conditions. Here, a combination of synchrotron-based (XRD and XANES) and vibrational (DRIFTS) spectroscopy tools have been used to follow the changes in the location and coordination environment of copper ions in a Cu-SSZ-13 zeolite during calcinations, reduction with CO, and adsorption of CO and H2O. XANES spectra collected during these procedures provides critical information not only on the variation in the oxidation state of the copper species in the zeolite structure, but also on the changes in the coordination environment around these ions as they interact with the framework, and with different adsorbates (H2O and CO). Time-resolved XRD data indicate the movement of copper ions and the consequent variation of the unit cell parameters during dehydration. DRIFT spectra provide information about the adsorbed species present in the zeolite, as well as the oxidation states of and coordination environment around the copper ions. A careful analysis of the asymmetric T-O-T vibrations of the CHA framework perturbed by copper ions in different coordination environments proved to be especially informative. The results of this study will aid the identification of the location, coordination and oxidation states of copper ions obtained during in operando catalytic studies. Financial support was provided by the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program. Part of this work (sample preparation) was performed in the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). The EMSL is a national scientific user facility supported by the US DOE, Office of Biological and Environmental Research. PNNL is a multi-program national laboratory operated for the US DOE by Battelle. All of the spectroscopy work reported here was carried out at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL). NSLS is a national scientific user facility supported by the US DOE.

  16. Photocatalyzed oxidation of hydrocarbons in zeolite cages

    SciTech Connect

    Frei, H.; Blatter, F.; Sun, H. [Lawrence Berkeley National Lab., CA (United States)

    1996-06-01

    Oxidation of hydrocarbons by molecular oxygen is a key process in chemical industry. But reactions that use O{sub 2} as the primary oxidant often produce large amounts of unwanted byproducts. One major reason that selectivities are low is that the desired products (such as alcohols or carbonyls) are more easily oxidized by O{sub 2} than the parent hydrocarbon. The authors recently discovered a simple method that gives partial oxidation of small alkenes, alkanes, and alkyl-substituted benzenes by O{sub 2} at unprecedented selectivity, even at high conversion of the hydrocarbon. The approach is based on visible light-induced chemistry of hydrocarbon-O{sub 2} collisional pairs in the cages of large-pore zeolites. Reactions are conducted at ambient temperature in the absence of solvent or photosensitizer. Here the authors describe the most interesting reactions established thus far and define issues that pertain to scale-up of the method.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  19. Adsorption and isothermal models of atrazine by zeolite prepared from Egyptian kaolin

    NASA Astrophysics Data System (ADS)

    Jamil, Tarek S.; Gad-Allah, Tarek A.; Ibrahim, Hanan S.; Saleh, Tamer S.

    2011-01-01

    The adsorption behavior of Atrazine on zeolites, prepared from Egyptian kaolin, has been studied in order to consider the application of these types of zeolites in water purification. The batch mode has been employed, using atrazine solution of concentration ranging from 2 to 10 mg /l. The adsorption capacity and distribution coefficients ( Kd) were determined for the adsorption system as a function of sorbate concentration. It was found that, under the studies concentrations, the percent of adsorbed atrazine on both zeolites match to Langmuir and Freundlich adsorption models. The constants of each model were calculated to assess the adsorption behavior of atrazine on each type of zeolite. According to the equilibrium studies, adsorption of atrazine on zeolite X at lower concentrations is much better than that on zeolite A. The application of Dublin-Kaganer-Radushkevich model revealed physisorption endothermic adsorption process for both zeolites. These results show that natural zeolites hold great potential to remove hazardous materials such as atrazine from water.

  20. Biogenic nanoparticles: copper, copper oxides, copper sulphides, complex copper nanostructures and their applications.

    PubMed

    Rubilar, Olga; Rai, Mahendra; Tortella, Gonzalo; Diez, Maria Cristina; Seabra, Amedea B; Durán, Nelson

    2013-09-01

    Copper nanoparticles have been the focus of intensive study due to their potential applications in diverse fields including biomedicine, electronics, and optics. Copper-based nanostructured materials have been used in conductive films, lubrification, nanofluids, catalysis, and also as potent antimicrobial agent. The biogenic synthesis of metallic nanostructured nanoparticles is considered to be a green and eco-friendly technology since neither harmful chemicals nor high temperatures are involved in the process. The present review discusses the synthesis of copper nanostructured nanoparticles by bacteria, fungi, and plant extracts, showing that biogenic synthesis is an economically feasible, simple and non-polluting process. Applications for biogenic copper nanoparticles are also discussed. PMID:23690046

  1. One-pot synthesis of hierarchical FeZSM-5 zeolites from natural aluminosilicates for selective catalytic reduction of NO by NH3.

    PubMed

    Yue, Yuanyuan; Liu, Haiyan; Yuan, Pei; Yu, Chengzhong; Bao, Xiaojun

    2015-01-01

    Iron-modified ZSM-5 zeolites (FeZSM-5s) have been considered to be a promising catalyst system to reduce nitrogen oxide emissions, one of the most important global environmental issues, but their synthesis faces enormous economic and environmental challenges. Herein we report a cheap and green strategy to fabricate hierarchical FeZSM-5 zeolites from natural aluminosilicate minerals via a nanoscale depolymerization-reorganization method. Our strategy is featured by neither using any aluminum-, silicon-, or iron-containing inorganic chemical nor involving any mesoscale template and any post-synthetic modification. Compared with the conventional FeZSM-5 synthesized from inorganic chemicals with the similar Fe content, the resulting hierarchical FeZSM-5 with highly-dispersed iron species showed superior catalytic activity in the selective catalytic reduction of NO by NH3. PMID:25791958

  2. Adsorption properties of Fe-containing dealuminated BEA zeolites as revealed by FTIR spectroscopy

    Microsoft Academic Search

    Konstantin Hadjiivanov; Elena Ivanova; Radoslav Kefirov; Janusz Janas; Anna Plesniar; Stanislaw Dzwigaj; Michel Che

    2010-01-01

    Adsorption properties of Fe-containing dealuminated BEA zeolites were investigated by FTIR spectroscopy of adsorbed CO and NO. Two Fe-containing SiBEA zeolite samples were prepared by a two-step post-synthesis method: creation of vacant T-atom sites (T=Si, Al) by dealumination of tetraethylammonium BEA zeolite with nitric acid followed by impregnation of the resulting SiBEA zeolite with an aqueous solution of Fe(NO3)3. The

  3. Removal of organobromine compounds from the pyrolysis oils of flame retarded plastics using zeolite catalysts

    Microsoft Academic Search

    William J. Hall; Paul T. Williams

    2008-01-01

    Two flame retarded plastics have been pyrolysed in the presence of two zeolite catalysts to remove the organobromine compounds from the derived pyrolysis oil. The flame retarded plastics were, acrylonitrile–butadiene–styrene (ABS) that was flame retarded with tetrabromobisphenol A and high impact polystyrene (HIPS) that was flame retarded with decabromodiphenyl ether. The two catalysts investigated were zeolite ZSM-5 and zeolite Y-Zeolite.

  4. High adherence copper plating process

    DOEpatents

    Nignardot, Henry (Tesuque, NM)

    1993-01-01

    A process for applying copper to a substrate of aluminum or steel by electrodeposition and for preparing an aluminum or steel substrate for electrodeposition of copper. Practice of the invention provides good adhesion of the copper layer to the substrate.

  5. Highly dispersed metal atoms in zeolites. Progress report. [Hydroformylation

    SciTech Connect

    Suib, S.L.

    1985-04-15

    Our studies this past year have involved work in the following areas: preparation of highly dispersed metal atoms in molecular sieves via microwave discharge methods, hydroformylation of l-pentene with rhodium zeolites and Rutherford backscattering studies of zeolites. The microwave discharge method has been developed by us to provide a synthetic route to produce highly dispersed iron and cobalt atom clusters in several molecular sieves such as zeolites, aluminophosphates, pillared clays and clays. We have done ferromagnetic resonance, infrared, Mossbauer and scanning electron microscopy experiments on these materials. Generalizations that can be made so far are that these particles are extremely small, reactive and their formation is governed by the type of support. They are all active in Fischer-Tropsch reactions although cobalt materials are more selective and stable than iron materials. Superparamagnetic iron clusters have been observed for the incorporation of iron into zeolites, ALPO's and pillared clays. These results are unique in that iron (0) is usually oxidized in a zeolite environment. The second project deals with Wilkinson's catalyst and the preparation of phosphine rhodium zeolite catalysts. These catalysts are selective towards aldehyde formation and the normal to branched aldehyde ratio can be controlled. EXAFS, Fourier transform infrared and x-ray powder diffraction experiments have been carried out on these catalysts. The third project deals with Rutherford backscattering studies of zeolites. We have shown that Rutherford backscattering methods can be used to distinguish metal ions on the surface of a porous support from internal metal ions exchanged into the pores of the support.

  6. The role of zeolite beta nanoparticles solutions in the synthesis of zeolite-functionalised materials with bimodal porosity

    NASA Astrophysics Data System (ADS)

    Van Oers, Cynthia J.

    The last decade, much attention has been devoted to the development of bimodal materials with zeolitic properties, with the intention to combine the beneficial properties of zeolites with these of mesoporous structures. Various synthesis methods have been developed, of which several are using zeolite nanoparticles solutions as silica-alumina source to form the mesoporous material. Extensive research has been conducted to the properties and the formation mechanism of both the nanoparticles solution and the final bimodal materials. However, still little is known about the correlation between the characteristics of the initial nanoparticles solution and the structural, chemical and physico-chemical properties of the final materials. The focus of this research is to acquire this lacking knowledge, which would allow tailoring of the final material characteristics, depending on the application requirements. In this PhD work, two types of bimodal materials with zeolitic features are investigated, i.e. a mesotemplate-free method and an impregnation on a mesoporous substrate, both using a zeolite beta nanoparticles solution as precursor. The main focus is put on how the synthesis conditions of the zeolite beta nanoparticles solution influence the final material properties. It is shown that the hydrothermal synthesis temperature (373K--393K--413K--423K/24h) of the zeolite beta nanoparticles solution has a direct impact on the porosity and zeolitic features of the final materials. Moreover, a clear threshold is observed: Synthesis temperatures below or equal to 413K result in bimodal materials without clear zeolitic properties, while a higher temperature of 423K gives materials with clear zeolitic features. Furthermore, this difference in material properties gives better results for the materials above the threshold regarding the acidity, stability and catalytic activity. A transmission electron microscopy and advanced electron tomography study showed that the mesotemplate-free structures are possessing a wormhole-like mesoporous structure, formed by the condensation of nanoparticles via neck formation. Furthermore, the study revealed a 2D growth of the nanoparticles under the threshold and a change towards 3D growth at the threshold temperature of 413K. This suggests a standard sol-mechanism below and at the threshold, and indicates an interruption of this mechanism by the start of the crystallisation process above 413K.

  7. Modified activated carbon for the removal of copper, zinc, chromium and cyanide from wastewater

    Microsoft Academic Search

    Lotfi Monser; Nafaâ Adhoum

    2002-01-01

    Modified activated carbon are carbonaceous adsorbents which have tetrabutyl ammonium iodide (TBAI) and sodium diethyl dithiocarbamate (SDDC) immobilised at their surface. This study investigates the adsorption of toxic ions, copper, zinc, chromium and cyanide on these adsorbents that have undergone surface modification with tetrabutyl ammonium (TBA) and SDDC in wastewater applications. The modification technique enhance the removal capacity of carbon

  8. Solid-liquid-solid extraction of heavy metals (Cr, Cu, Cd, Ni and Pb) in aqueous systems of zeolite-sewage sludge.

    PubMed

    Sprynskyy, Myroslav

    2009-01-30

    This paper presents results of kinetic and equilibrium studies of the removal of heavy metals (Cr, Cu, Cd, Ni and Pb) from the sewage sludge using a new technique of solid-liquid-solid extraction with the adsorption-diffusion column filled by the zeolite. The metal extraction onto the zeolite from aqueous solution of the clinoptilolite and the sludge composition is characterized by three stages: intensive extraction, inversion and stabilization with the moderate extraction increase. Addition of 25% of the zeolite provides extraction efficiency of cadmium and lead of about 84%, chromium, copper and nickel of 66%, 61% and 50%, respectively. The estimated values of Gibbs free energy change DeltaG show that the metals extraction by the clinoptilolite may be considered as a physical adsorption. The negative values of DeltaG testify to an exothermic nature of the process. The difference between energetic potentials of the components is a driving force of the metal redistribution in the system "clinoptilolite-water-sludge". PMID:18538472

  9. Studies on catalytic cracking catalyst of hydrocarbons with a new type of zeolite L

    Microsoft Academic Search

    Huifang Pan; Guoyou Wei; Hailiang Yuan; Quan Huo; Qiang Li; Xinghong Pan; Wenhong Wang; Xiangzhen Yu

    2007-01-01

    A new catalyst which exhibits superior activity, stability and selectivity in fluid catalytic cracking (FCC) reactions of hydrocarbons is defined as a new type of zeolite L, ultra stable zeolite L (USL), as an active additive component of catalyst. The zeolite L was synthesized by hydrothermal crystallization method and characterized by means of XRD, SEM, FTIR and N2 isotherm adsorption.

  10. Competitive adsorption of malachite green and Pb ions on natural zeolite

    Microsoft Academic Search

    Shaobin Wang; Eko Ariyanto

    2007-01-01

    A natural zeolite was employed as adsorbent for removal of malachite green and Pb2+ ions from aqueous solution. A batch system was applied to study the adsorption behaviour of the dye and heavy metal in single and binary systems on the natural zeolite. Kinetic studies indicate that malachite green and Pb2+ adsorption on the natural zeolite in a single component

  11. Dealumination–aging pattern of REUSY zeolites contained in fluid cracking catalysts

    Microsoft Academic Search

    Francisco Hernández-Beltrán; Juan Carlos Moreno-Mayorga; Mar??a de Lourdes Guzmán-Castillo; Juan Navarrete-Bolaños; Montserrat González-González; Brent E. Handy

    2003-01-01

    The evolution of the properties of a REUSY zeolite contained in a fluid cracking catalyst was investigated under laboratory steam deactivation procedures and in age fractions of the corresponding equilibrium catalyst (Ecat). The aging pattern, defined by the evolution of the zeolite surface area (ZSA) related to the decrease of the unit cell size (UCS), was similar between lab-steamed zeolites

  12. Thermal Conductivity in Zeolites Studied by Non-equilibrium Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Schnell, Sondre K.; Vlugt, Thijs J. H.

    2013-07-01

    The thermal conductivity of zeolites is an important material property. For example, this is the case for catalysis, where chemical reactions release heat either inside zeolites or at zeolite surfaces. At zeolite surfaces, heat is released during the adsorption of guest molecules. Unfortunately, it can be difficult to determine the thermal conductivity of zeolites from experiments or from equilibrium molecular dynamics simulations. Non-equilibrium molecular dynamics (NEMD) simulation is an interesting approach to determine thermal conductivities. Inducing a thermal gradient by moving kinetic energy between different parts of the simulation box, and then studying the resulting thermal gradient, will lead to direct access to the thermal conductivity of the zeolite. In this work, we have used NEMD simulations to determine the thermal conductivity of several pure silica zeolites. The zeolites are modeled using the Demontis force field, making it possible to screen many zeolite frameworks, and study finite-size effects. In addition, we have studied the influence of adsorbed guest molecules on the thermal conductivity. The thermal conductivity of zeolites is usually in order of 0.6 to almost 4 , with large differences between different crystallographic directions. We find that the loading of guest molecules adsorbed inside the zeolite has a minor influence on the thermal conductivity, and that in general the thermal conductivity increases with increasing framework density of the zeolite.

  13. Significant reduction of carcinogenic compounds in tobacco smoke by the use of zeolite catalysts

    Microsoft Academic Search

    W. M Meier; K Siegmann

    1999-01-01

    Zeolites play an increasingly important role in toxicology and the life sciences. A new example is the removal of significant amounts of carcinogenic compounds from cigarette smoke. These compounds, particularly nitrosamines and polycyclic aromatics (PAHs), are well known to constitute a serious health risk. Most effective in reducing toxic compounds are zeolite catalysts placed directly on the tobacco. The zeolite

  14. Strategies for total NOx measurement with minimal CO interference utilizing a microporous zeolitic catalytic filter

    E-print Network

    Dutta, Prabir K.

    at temperatures greater than 400 8C. By using a Pt-loaded zeolite Yas a catalyst filter bed placed before a sensor a layer of the Pt-zeolite catalyst filter material directly onto a Pt electrode, a pseudo-reference to NOxStrategies for total NOx measurement with minimal CO interference utilizing a microporous zeolitic

  15. Zeolite Membrane for Dehydration of Isopropylalcohol-Water Mixture by Vapor Permeation.

    PubMed

    Sawamura, Ken-Ichi; Furuhata, Taisuke; Sekine, Yasushi; Kikuchi, Eiichi; Subramanian, Bharathi; Matsukata, Masahiko

    2015-07-01

    Highly stable FAU-type zeolite membrane for the separation of isopropanol (IPA)-water mixture by pervaporation is described. FAU membrane showed high water permselectivity and permeance. Comparison of FAU membrane with a conventional LTA-type zeolite membrane revealed superior stability of FAU zeolite membrane in a mixture containing a large water content. PMID:26076213

  16. Role of acidity in hydrogenation of cinnamaldehyde on platinum beta zeolite

    Microsoft Academic Search

    Mohamed Lashdaf; Ville-Veikko Nieminen; Marja Tiitta; Tapani Venäläinen; Heidi Österholm; Outi Krause

    2004-01-01

    A series of platinum beta zeolites with different well-defined acid properties were tested in cinnamaldehyde hydrogenation. The acetal formation was found to be related to the amount of acid sites on the external surface of the zeolite. The acidity of the beta zeolite influenced the platinum dispersion, and the activity of the catalysts increased with total acidity of the beta

  17. Acidity and catalytic activity of zeolite catalysts bound with silica and alumina

    E-print Network

    Wu, Xianchun

    2004-09-30

    -framework alumina in zeolites to form a new protonic acid. SiO2-bound catalysts have less strong acidity, Bronsted acidity and Lewis acidity than the zeolite powder. Also, the strength of strong acid sites of the zeolites is reduced when silica is embedded...

  18. Copper Delivery by Metallochaperone Proteins

    SciTech Connect

    Rosenzweig, A.C. (NWU)

    2010-03-08

    Copper is an essential element in all living organisms, serving as a cofactor for many important proteins and enzymes. Metallochaperone proteins deliver copper ions to specific physiological partners by direct protein-protein interactions. The Atx1-like chaperones transfer copper to intracellular copper transporters, and the CCS chaperones shuttle copper to copper,zinc superoxide dismutase. Crystallographic studies of these two copper chaperone families have provided insights into metal binding and target recognition by metallochaperones and have led to detailed molecular models for the copper transfer mechanism.

  19. Pulsed copper halide vapor lasers

    NASA Astrophysics Data System (ADS)

    Kazarian, M. A.; Petrash, G. G.; Trofimov, A. N.

    The theory and the performance characteristics of copper halide lasers are examined with reference to recent theoretical and experimental research in the field of metal vapor lasers. The discussion covers gas discharge tubes, comparative characteristics of copper halide lasers, determination of the metastable level decomposition rates in copper chloride and copper bromide lasers, and spectroscopic measurements of the discharge plasma in copper halide lasers. Attention is also given to the kinetics of copper atoms formation in copper halide lasers and calculation of the kinetic characteristics of copper halide lasers.

  20. Mechanical durability of superhydrophobic and oleophobic copper meshes

    NASA Astrophysics Data System (ADS)

    Yin, Linting; Yang, Jin; Tang, Yongcai; Chen, Lin; Liu, Can; Tang, Hua; Li, Changsheng

    2014-10-01

    We developed a simple and inexpensive method to prepare the superhydrophobic and oleophobic copper meshes with rough structures fabrication and chemical modification. The achieved surfaces displayed liquid-repellent toward water and several organic liquids (such as hexadecane), which possessed much lower surface tension than that of water. Liquid repellency of the fabricated superhydrophobic copper mesh was demonstrated by visible experiment results and contact angle measurements. Even if the superhydrophobic copper mesh was rolled up, it still kept the superhydrophobicity. The mechanical durability was investigated by finger touch and mechanical abrasion tests. The results indicated that the copper mesh can maintain its superhydrophobicity against an abrasion length of 300 cm under a high pressure (77.2 kPa). The superhydrophobicity and oleophobicity, combined with mechanical durability, would promote the superhydrophobic surface to practical application in industry in the future.

  1. SO2 REMOVAL FROM FLUE GASES USING UTILITY SYNTHESIZED ZEOLITES

    SciTech Connect

    MICHAEL GRUTZECK

    1998-10-31

    It is well known that natural and synthetic zeolites (molecular sieves) can adsorb gaseous SO2 from flue gas and do it more efficiently than lime based scrubbing materials. Unfortunately their cost ($500-$800 per ton) has deterred their use in this capacity. It is also known that zeolites are easy to synthesize from a variety of natural and man-made materials. The overall objective of the current work has been to evaluate the feasibility of having a utility synthesize its own zeolites, on-site, from fly ash and other recycled materials and then use these zeolites to adsorb SO2 from their flue gases. Work to date has shown that the efficiency of the capture process is related to the degree of crystallinity and the type of zeolite that forms in the samples. Normally, those samples cured at 150°C contained a greater proportion of zeolite and as such were more SO2 adsorptive than their low-temperature counterparts. However, in order for the project to be successful, on site synthesis must remain an option, i.e. _100°C synthesis. In light of this, the experimental focus now has two aspects. First, compositions of the starting materials are being altered by blending the current suite of fly ashes with other fly ashes, ground glass cullet and silica fume to promote the formation and growth of well crystallized and highly adsorptive zeolites. Second, greater degrees of reaction at significantly lower temperatures are being promote by ball milling the fly ash prior to use, by the use of more concentrated caustic solutions, and by the addition of zeolite seeds to the reactants. In all cases studies will focus on the effect of structure type and degree of conversion on SO2 adsorption. Future work will concentrate on the study of the effect of weathering on the suitability of converting fly ash into zeolites. This is an especially important study, considering the acres of fly ash now in storage throughout the country.

  2. SO2 REMOVAL FROM FLUE GASES USING UTILITY SYNTHESIZED ZEOLITES

    SciTech Connect

    Michael Grutzeck

    1999-04-30

    It is well known that natural and synthetic zeolites (molecular sieves) can adsorb gaseous SO{sub 2} from flue gas and do it more efficiently than lime based scrubbing materials. Unfortunately their cost ($500-$800 per ton) has deterred their use in this capacity. It is also known that zeolites are easy to synthesize from a variety of natural and man-made materials. The overall objective of the current work has been to evaluate the feasibility of having a utility synthesize its own zeolites, on-site, from fly ash and other recycled materials and then use these zeolites to adsorb SO{sub 2} from their flue gases. Work to date has shown that the efficiency of the capture process is related to the degree of crystallinity and the type of zeolite that forms in the samples. Normally, those samples cured at 150 C contained a greater proportion of zeolite and as such were more SO{sub 2} adsorptive than their low-temperature counterparts. However, in order for the project to be successful, on site synthesis must remain an option, i.e. 100 C synthesis. In light of this, the experimental focus now has two aspects. First, compositions of the starting materials are being altered by blending the current suite of fly ashes with ground glass cullet and silica fume to promote the formation and growth of well crystallized and highly adsorptive zeolites. Second, greater degrees of reaction at significantly lower temperatures are being promote by ball milling the fly ash prior to use, by the use of more concentrated caustic solutions, and by the addition of zeolite seeds to the reactants. In all cases studies will focus on the effect of structure type and degree of conversion on SO{sub 2} adsorption. Future work will concentrate on the study of the effect of weathering on the suitability of converting fly ash into zeolites. This is an especially important study, considering the acres of fly ash now in storage throughout the US.

  3. Zeolites for the selective adsorption of sulfur hexafluoride.

    PubMed

    Matito-Martos, I; Álvarez-Ossorio, J; Gutiérrez-Sevillano, J J; Doblaré, M; Martin-Calvo, A; Calero, S

    2015-07-01

    Molecular simulations have been used to investigate at the molecular level the suitability of zeolites with different topology on the adsorption, diffusion and separation of a nitrogen-sulfur hexafluoride mixture containing the latter at low concentration. This mixture represents the best alternative for the sulfur hexafluoride in industry since it reduces the use of this powerful greenhouse gas. A variety of zeolites are tested with the aim to identify the best structure for the recycling of sulfur hexafluoride in order to avoid its emission to the atmosphere and to overcome the experimental difficulties of its handling. Even though all zeolites show preferential adsorption of sulfur hexafluoride, we identified local structural features that reduce the affinity for sulfur hexafluoride in zeolites such as MOR and EON, providing exclusive adsorption sites for nitrogen. Structures such as ASV and FER were initially considered as good candidates based on their adsorption features. However, they were further discarded based on their diffusion properties. Regarding operation conditions for separation, the range of pressure that spans from 3 × 10(2) to 3 × 10(3) kPa was identified as the optimal to obtain the highest adsorption loading and the largest SF6/N2 selectivity. Based on these findings, zeolites BEC, ITR, IWW, and SFG were selected as the most promising materials for this particular separation. PMID:26099734

  4. A high acid mesoporous USY zeolite prepared by alumination

    NASA Astrophysics Data System (ADS)

    Ma, Jinghong; Kang, Yuhong; Ma, Ning; Hao, Wenming; Wang, Yan; Li, Ruifeng

    2013-01-01

    A high-acidity HUSY zeolite with mesoporous structure was prepared by alumination with a dilute aqueous NaAlO2 solution and characterized by XRD, N2 adsorption, IR framework vibration and 29Si MAS NMR methods. The results indicated the extra-framework aluminum was reinserted into the tetrahedral framework through isomorphic substitution of framework Si (0Al) sites by Al ions, whereas the crystal and micropore structure were unaltered. FTIR spectra of hydroxyl vibrations and pyridine adsorbed on realuminated zeolites showed that the number of Brønsted acid sites and strong Lewis acid sites increased whereas weak Lewis acid sites decreased twice. The mesoporous structure composed of inter-and intra-crystalline pores in the aluminated HUSY increased the external surface area of the zeolite, improving accessibility of molecules to the active sites and enhancing its catalytic ability. The realuminated HUSY zeolite supported with Ru catalyst exhibited a higher catalytic activity for benzene hydrogenation than the parent HUSY zeolite; the reaction rate in comparison to the mesozeolite increased by 5.5 times.

  5. Bendable Zeolite Membranes: Synthesis and Improved Gas Separation Performance.

    PubMed

    Wang, Bo; Ho, W S Winston; Figueroa, Jose D; Dutta, Prabir K

    2015-06-23

    Separation and sequestration of CO2 emitted from fossil energy fueled electric generating units and industrial facilities will help in reducing anthropogenic CO2, thereby mitigating its adverse climate change effects. Membrane-based gas separation has the potential to meet the technical challenges of CO2 separation if high selectivity and permeance with low costs for large-scale manufacture are realized. Inorganic zeolite membranes in principle can have selectivity and permeance considerably higher than polymers. This paper presents a strategy for zeolite growth within the pores of a polymer support, with crystallization time of an hour. With a thin coating of 200-300 nm polydimethylsiloxane (PDMS) on the zeolite-polymer composite, transport data for CO2/N2 separation indicate separation factors of 35-45, with CO2 permeance between 1600 and 2200 GPU (1 GPU = 3.35 × 10(-10) mol/(m(2) s Pa)) using dry synthetic mixtures of CO2 and N2 at 25 °C. The synthesis process results in membranes that are highly reproducible toward transport measurements and exhibit long-term stability (3 days). Most importantly, these membranes because of the zeolite growth within the polymer support, as contrasted to conventional zeolite growth on top of a support, are mechanically flexible. PMID:26030505

  6. Refractories for Copper Production

    Microsoft Academic Search

    MARK E. SCHLESINGER

    1996-01-01

    The furnaces used for producing molten copper from concentrates and scrap - flash: smelters, converters, and anode and fire-refining furnaces - present a unique combination of challenges to refractory life. Highly aggressive slags, mechanical stresses, batch operation, and increasingly higher operating temperatures all combine to destroy most refractory materials. Over the past generation, copper producers have adopted refractory materials biased

  7. Ions Sputtered from Copper

    Microsoft Academic Search

    R. C. Bradley; E. Ruedl

    1962-01-01

    Positive ions sputtered from copper under a variety of different bombardment and surface conditions have been mass analyzed and found to include species characteristic of the incident ions (``reflected'' ions), of copper and some of its compounds, and of alkali metal impurities. A model is described which accounts for most of the properties of the ``reflected'' ions, not in terms

  8. Fabrication of high wettability gradient on copper substrate

    NASA Astrophysics Data System (ADS)

    Huang, Ding-Jun; Leu, Tzong-Shyng

    2013-09-01

    Copper is one of the most widely used materials in condensation heat transfer. Recently there has been great interest in improving the condensation heat transfer efficiency through copper surface modification. In this study, we describe the fabrication processes of how copper surfaces were modified to be superhydrophilic (CA ? 10°) and superhydrophobic (CA > 150°) by means of H2O2 immersion and fluorination with Teflon. The wettability gradient of copper surfaces with contact angles (CA) changing from superhydrophilic to superhydrophobic are also demonstrated. Unlike previous studies on gradient surfaces in which the wettability gradient is controlled either non-precisely or entirely uncontrolled, in this study, the contact angles along wettability gradient copper surfaces vary with a precisely designed gradient. It is demonstrated that a high wettability gradient copper surface can be successfully fabricated using photolithography to define the area ratios between superhydrophilic and superhydrophobic patterns within a short distance. The fabricated wettability gradient of copper surfaces is expected to be able to enhance the condensation heat transfer efficiency.

  9. Erythrocyte membrane proteins in copper-deficient rats

    SciTech Connect

    Johnson, W.T.; Kramer, T.R.

    1987-05-01

    Increased osmotic stability and decreased survivability of erythrocytes caused by Cu deficiency suggest that low copper status may lead to modification in the organization of erythrocyte membrane proteins. Accordingly Cu deficiency was produced in rats by feeding a diet containing < 1 ppm Cu. The effects of low copper status on erythrocyte membrane proteins were assessed by sodium dodecyl sulfate polyacylamide electrophoresis. A 170,000 dalton protein (170K) amounted to 2.68 +/- 0.11% of the total membrane protein in erythrocytes from copper-deficient rats (n = 25) and 1.42 +/- 0.10% in erythrocytes from rats fed adequate Cu. When erythrocyte membranes from copper-deficient rats were extracted with 0.5% (v/v) Triton X-100, 170K remained associated with the cytoskeletal proteins, spectrin and actin. Thus, copper deficiency can alter the composition of the erythrocyte cytoskeleton. Furthermore, hematocrit levels in copper-deficient rats were negatively correlated to the amount of 170K suggesting that alteration of the erythrocyte cytoskeleton may be a factor that contributes to the anemia associated with copper deficiency.

  10. Bioaccessibility and Solubility of Copper in Copper-Treated Lumber

    EPA Science Inventory

    Micronized copper (MC)-treated lumber is a recent replacement for Chromated Copper Arsenate (CCA) and Ammonium Copper (AC)-treated lumbers; though little is known about the potential risk of copper (Cu) exposure from incidental ingestion of MC-treated wood. The bioaccessibility o...

  11. Synthesis of chiral polymorph A-enriched zeolite Beta with an extremely concentrated fluoride route.

    PubMed

    Tong, Mingquan; Zhang, Daliang; Fan, Weibin; Xu, Jun; Zhu, Liangkui; Guo, Wen; Yan, Wenfu; Yu, Jihong; Qiu, Shilun; Wang, Jianguo; Deng, Feng; Xu, Ruren

    2015-01-01

    Chiral zeolitic materials with intrinsically chiral frameworks are highly desired because they can combine both shape selectivity and enantioselectivity. In the field of zeolite, the synthesis of chiral polymorph A of zeolite Beta or chiral polymorph A-enriched zeolite Beta is one of the biggest challenges. We demonstrate here a generalized extremely concentrated fluoride route for the synthesis of chiral polymorph A-enriched zeolite Beta in the presence of five achiral organic structure-directing agents. The polymorph A-enriched Ti-Beta shows a higher enantioselectivity for the asymmetric epoxidation of alkenes than the normal Ti-Beta. PMID:26096214

  12. Synthesis of chiral polymorph A-enriched zeolite Beta with an extremely concentrated fluoride route

    PubMed Central

    Tong, Mingquan; Zhang, Daliang; Fan, Weibin; Xu, Jun; Zhu, Liangkui; Guo, Wen; Yan, Wenfu; Yu, Jihong; Qiu, Shilun; Wang, Jianguo; Deng, Feng; Xu, Ruren

    2015-01-01

    Chiral zeolitic materials with intrinsically chiral frameworks are highly desired because they can combine both shape selectivity and enantioselectivity. In the field of zeolite, the synthesis of chiral polymorph A of zeolite Beta or chiral polymorph A-enriched zeolite Beta is one of the biggest challenges. We demonstrate here a generalized extremely concentrated fluoride route for the synthesis of chiral polymorph A-enriched zeolite Beta in the presence of five achiral organic structure-directing agents. The polymorph A-enriched Ti-Beta shows a higher enantioselectivity for the asymmetric epoxidation of alkenes than the normal Ti-Beta. PMID:26096214

  13. Catalytic pyrolysis using UZM-39 aluminosilicate zeolite

    DOEpatents

    Nicholas, Christopher P; Boldingh, Edwin P

    2014-10-07

    A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and shown to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub.1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  14. Synthetic Zeolites and Other Microporous Oxide Molecular Sieves

    NASA Astrophysics Data System (ADS)

    Sherman, John D.

    1999-03-01

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol.

  15. Safe trapping of Cs in heat-treated zeolite matrices

    NASA Astrophysics Data System (ADS)

    Bosch, P.; Caputo, D.; Liguori, B.; Colella, C.

    2004-01-01

    Cesium retention performances of two different natural zeolites (an Italian phillipsite-rich tuff and a Mexican erionite-rich tuff), pre-exchanged in Cs form and heat-treated, are compared. After thermal treatment at 1000 °C both zeolites satisfactorily retain Cs during back-exchange tests with NaCl solution or by a prolonged contact with distilled water. The different mechanisms of Cs encapsulation are elucidated. The Cs-exchanged phillipsite, a less siliceous and less heat-stable zeolite, tends to form pollucite on heating. Pollucite is a naturally occurring mineral phase which contains and irreversibly traps cesium. The Cs-exchanged erionite tends to form an amorphous phase on heating and Cs is immobilized through glass formation.

  16. Synthesis of self-pillared zeolite nanosheets by repetitive branching.

    PubMed

    Zhang, Xueyi; Liu, Dongxia; Xu, Dandan; Asahina, Shunsuke; Cychosz, Katie A; Agrawal, Kumar Varoon; Al Wahedi, Yasser; Bhan, Aditya; Al Hashimi, Saleh; Terasaki, Osamu; Thommes, Matthias; Tsapatsis, Michael

    2012-06-29

    Hierarchical zeolites are a class of microporous catalysts and adsorbents that also contain mesopores, which allow for fast transport of bulky molecules and thereby enable improved performance in petrochemical and biomass processing. We used repetitive branching during one-step hydrothermal crystal growth to synthesize a new hierarchical zeolite made of orthogonally connected microporous nanosheets. The nanosheets are 2 nanometers thick and contain a network of 0.5-nanometer micropores. The house-of-cards arrangement of the nanosheets creates a permanent network of 2- to 7-nanometer mesopores, which, along with the high external surface area and reduced micropore diffusion length, account for higher reaction rates for bulky molecules relative to those of other mesoporous and conventional MFI zeolites. PMID:22745424

  17. Monodispersed Ultrafine Zeolite Crystal Particles by Microwave Hydrothermal Synthesis

    SciTech Connect

    Hu, Michael Z. [ORNL; Harris, Michael Tyrone [ORNL; Khatri, Lubna [ORNL

    2008-01-01

    Microwave hydrothermal synthesis of zeolites is reviewed. Monodispersed ultrafine crystal particles of zeolite (Silicalite-1) have been synthesized in batch reactor vessels by microwave irradiation heating of aqueous basic silicate precursor solutions with tetra propyl ammonium hydroxide as the templating molecule. The effects of major process parameters (such as synthesis temperature, microwave heating rate, volume ratio (i.e., the volume of the initial synthesis solution over the total volume of the reactor vessel), and synthesis time on the zeolite particle characteristics are studied using a computer-controlled microwave reactor system that allows real-time monitoring and control of reaction medium temperature. The changes in the morphology, size and crystal structure of the particles are investigated using scanning electron microscope, dynamic light scattering, X-ray diffraction, and BET surface analysis. We have found that the synthesis temperature, volume ratio, and heating rate play a significant role in controlling the particle size, uniformity, and morphology. Microwave processing has generated new morphologies of zeolite particles (i.e., uniform block-shaped particles that contain mixed gel-nanocrystallites and agglomerated crystal particles) that could not be made by a conventional hydrothermal process. At higher synthesis temperature and lower volume ratio, irregular block-shaped particles were produced, whereas increasing the volume ratio promoted the formation of monodispersed single-crystal particles with uniform shape. Our results clearly demonstrate that faster microwave heating is advantageous to enhance the zeolite crystallization kinetics and produces larger-size crystal particles in shorter time. In addition, zeolite crystallization mechanisms, depending on the microwave heating rate, were also discussed.

  18. Maximizing ammonium nitrogen removal from solution using different zeolites.

    PubMed

    Penn, Chad J; Warren, Jason G; Smith, Savannah

    2010-01-01

    Zeolite minerals are ideal for removing ammonium nitrogen (NH4(+)-N) from animal wastes, leachates, and industrial effluents. The objectives of this study were to compare NH4+ removal and kinetics among several commercially available zeolites under various conditions and determine if calorimetry could provide information regarding kinetics of NH4+ removal. Ammonium sorption onto potassium (K) saturated zeolites was compared using synthetic vs. natural swine effluent and with either traditional batch-shaken system or a "tea bag" approach in which zeolites were contained in a mesh sack and suspended in a solution of swine effluent. Ammonium sorption was measured at four retention times using a flow-through system, and the resulting heat response was measured using isothermal calorimetry. Ammonium removal was not significantly different in synthetic vs. natural swine effluent. Ammonium removal was lower in batch-stirred compared to batch-shaken systems, suggesting that diffusion between particles was rate-limiting in the former system. Flow-through cells possessing contact times > 100 s displayed greater NH4+ sorption than batch systems, suggesting that maintaining high NH4+ concentration in solution, removal of exchange products, and sufficient reaction time are critical to maximizing NH4+ removal by zeolites. Within 100 s after NH4+ addition, endothermic heat responses indicated that NH4(+)-K+ exchange had peaked; this was followed by significant heat rate reduction for 50 min. This confirmed findings of an initial fast NH4(+)-K+ exchange followed by a slower one and suggests the 100-s period of rapid reaction is an indicator of the minimum flow through retention time required to optimize NH4+ sorption to zeolites used in this study. PMID:20830934

  19. Effects of TS1 zeolite structures on physical properties and enzymatic degradation of Poly (butylene succinate) (PBS)\\/TS1 zeolite hybrid composites

    Microsoft Academic Search

    Sung Yeon Hwang; Eui Sang Yoo; Seung Soon Im

    2011-01-01

    The objective of this study was to investigate how the water uptake features and carrier characteristics of the TS-1 zeolite affected the physical and rheological properties, morphological parameters, and enzymatic hydrolysis of Poly (butylene succinate) (PBS). The introduction of TS-1 zeolite as catalyst was developed for the preparation of PBS\\/TS-1 zeolite hybrid composites (PTHC) without heavy metal toxic substance in

  20. Physical and Mechanical Properties of Copper and Copper Alloys

    Microsoft Academic Search

    Meimei Li; Steven J Zinkle

    2012-01-01

    High strength, high conductivity copper alloys are prime candidates for high heat flux applications in fusion energy systems. This chapter reviews the physical and mechanical properties of pure copper and copper alloys with the focus on precipitation-hardened CuCrZr and dispersion-strengthened CuAl25 alloys. The effect of neutron irradiation on copper and copper alloys is reviewed in terms of radiation effects on

  1. Copper sensitivity of Gonyaulax tamarensis

    Microsoft Academic Search

    D. M. Anderson; F. M. M. Morel

    1978-01-01

    The copper sensitivity of the dinoflagellate Gonyaulax tamarensis was examined in artificial seawater medium. Two short term responses of the organism to copper toxicity are rapid loss of motility and reduced photosynthetic carbon fixation. The chelators tris(hydroxymethylamino)methane (Tris) and ethylenedinitrilotetraacetic acid (EDTA) were used to demonstrate that copper toxicity is a unique function of cupric ion activity. Copper additions to

  2. Motion of organic species occluded or sorbed within zeolites

    SciTech Connect

    Newsam, J.M.; Silbernagel, B.G.; Melchior, M.T.; Brun, T.O.; Trouw, F.

    1988-01-01

    Containment of organic species within microporous materials such as zeolites influences their modes of molecular motion. This manifests itself in a range of ways, including a reduction in the volume that is readily accessible to the molecules by translation, constraints upon the molecular conformational space, restricted modes of molecular reorientation, or altered vibrational frequencies. The perspectives on certain of the motional properties of sorbates and of tetramethylammonium cations within zeolites provided by simple molecular modeling, neutron powder diffraction, /sup 13/C and /sup 2/H(D), and inelastic and quasielastic neutron scattering are outlined and illustrated by selected recent results. 56 refs., 5 figs.

  3. Single and Multiple Heteroatom Incorporation in MFI Zeolites

    E-print Network

    Garcia Vargas, Nataly

    2012-11-05

    International Zeolite Association MAS Magic Angle Spinning ix MFI Code for the structure of Zeolite Socony Mobil - Five (ZSM-5) MPV, MPVO Meerwein-Ponndorf-Verley, Meerwein-Ponndorf-Verley- Oppenauer NMR Nuclear Magnetic Resonance ONIOM Our Own N.................................................................................................91 3.9 27Al MAS NMR (left) and 29Si MAS NMR (right) of Ge-Al-MFI with a target composition of Si/Ge = 10 and Si/Al = 50 .........................................92 3.10 X-ray absorption near edge spectra of reference GeO2, Ge-Silicalite-1 and Ge...

  4. CO2 adsorption on LTA zeolites: Effect of mesoporosity

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Ahn, Wha-Seung

    2014-08-01

    Highly mesoporous LTA zeolite (Meso-LTA) was prepared using an organosilane surfactant, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, as a mesopore-generating agent. Meso-LTA was characterized by X-ray powder diffraction, N2 adsorption-desorption isotherm at 77 K, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, and then investigated for CO2 adsorption at 298 K. Compared to a solely microporous LTA zeolite (Micro-LTA), Meso-LTA showed faster CO2 adsorption kinetics at 1 bar and higher CO2 adsorption capacities under high pressure conditions (>10 bar).

  5. Potassium–copper and potassium–cobalt catalysts supported on alumina for simultaneous NO x and soot removal from simulated diesel engine exhaust

    Microsoft Academic Search

    N. Nejar; M. J. Illán-Gómez

    2007-01-01

    This paper deals with the activity of bimetallic potassium–copper and potassium–cobalt catalysts supported on alumina for the reduction of NOx with soot from simulated diesel engine exhaust. The effect of the reaction temperature, the soot\\/catalyst mass ratio and the presence of C3H6 has been studied. In addition, the behavior of two monometallic catalysts supported on zeolite beta (Co\\/beta and Cu\\/beta),

  6. COPPER CABLE RECYCLING TECHNOLOGY

    SciTech Connect

    Chelsea Hubbard

    2001-05-01

    The United States Department of Energy (DOE) continually seeks safer and more cost-effective technologies for use in deactivation and decommissioning (D&D) of nuclear facilities. The Deactivation and Decommissioning Focus Area (DDFA) of the DOE's Office of Science and Technology (OST) sponsors large-scale demonstration and deployment projects (LSDDPs). At these LSDDPs, developers and vendors of improved or innovative technologies showcase products that are potentially beneficial to the DOE's projects and to others in the D&D community. Benefits sought include decreased health and safety risks to personnel and the environment, increased productivity, and decreased costs of operation. The Idaho National Engineering and Environmental Laboratory (INEEL) generated a list of statements defining specific needs and problems where improved technology could be incorporated into ongoing D&D tasks. One such need is to reduce the volume of waste copper wire and cable generated by D&D. Deactivation and decommissioning activities of nuclear facilities generates hundreds of tons of contaminated copper cable, which are sent to radioactive waste disposal sites. The Copper Cable Recycling Technology separates the clean copper from contaminated insulation and dust materials in these cables. The recovered copper can then be reclaimed and, more importantly, landfill disposal volumes can be reduced. The existing baseline technology for disposing radioactively contaminated cables is to package the cables in wooden storage boxes and dispose of the cables in radioactive waste disposal sites. The Copper Cable Recycling Technology is applicable to facility decommissioning projects at many Department of Energy (DOE) nuclear facilities and commercial nuclear power plants undergoing decommissioning activities. The INEEL Copper Cable Recycling Technology Demonstration investigated the effectiveness and efficiency to recycle 13.5 tons of copper cable. To determine the effectiveness of separating out radioactive contamination, the copper cable was coated with a surrogate contaminant. The demonstration took place at the Bonneville County Technology Center in Idaho Falls, Idaho.

  7. Fabricating Copper Nanotubes by Electrodeposition

    NASA Technical Reports Server (NTRS)

    Yang, E. H.; Ramsey, Christopher; Bae, Youngsam; Choi, Daniel

    2009-01-01

    Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

  8. Effects of the zeolite framework on the adsorption of ethylene and benzene on alkali-exchanged zeolites: an ONIOM study

    Microsoft Academic Search

    Karan Bobuatong; Jumras Limtrakul

    2003-01-01

    The density functional theory (B3LYP\\/6-31G(d,p)) and our-own-N-layered integrated molecular orbital + molecular mechanics (ONIOM) approach utilizing two-layer ONIOM schemes (B3LYP\\/6-31G(d,p): UFF) have been employed to investigate the structures of alkali-exchanged faujasite (FAU) and ZSM-5 zeolites, and their interactions with ethylene and benzene. Inclusion of the extended zeolite framework has an effect on the structure and energetics of the adsorption complexes

  9. Chemical interactions in multimetal/zeolite catalysts

    SciTech Connect

    Sachtler, W.M.H.

    1992-02-07

    For Pt/NaY catalysts our analysis of the mechanism of metal particle formation has enabled us to produce at will samples which contain either the majority of the Pt particles in supercages, without filling these cages completely, or the Pt particles bulge into neighboring cages. The catalytic selectivity is distinctly different for these preparations, in the former case molecules can enter a supercage which is partially filled by the Pt cluster, in the second case adsorption takes place through the cage window. Applying the same principles of catalyst preparation of bimetallic catalysts enables us to produce PtCu particles in supercages of NaY, which contain, initially a Pt core, surrounded by a Cu mantle. Earlier we have found that Ni ions migrate into hexagonal prisms during calcination of Ni/NaY; this process can be partially suppressed by first filling these prisms with Mn or Cr ions. In more recent work we found that addition of Pt strongly lowers the temperature of Ni reduction. Part of the Ni ions is reduced by hydrogen while still inside the smaller cages. This reduction process is, however, reversible; at elevated temperature and in an inert atmosphere protons re-oxidize the Ni atoms and dihydrogen gas is developed. In this way it seems possible to count the Ni atoms in small cages. The calcination stage in the preparation of zeolite supported metals has been studied in considerable detail for Pd/NaY. The Pd is introduced as a tetrammin complex; during calcination the ammine ligands are successively oxidized. Once three ammine ligands are destroyed, the Pd ions which carry only one ligand, surprisingly jump from the supercages to the sodalite cage.

  10. Computational studies of polyelectrolytes containing zeolite fragments.

    SciTech Connect

    Lee, Y.-C.; Curtiss, L. A.; Ratner, M. A.; Shriver, D. F.; Northwestern Univ.

    1999-08-05

    The structures and sodium affinities of a series of zeolitic fragments [H{sub 3}Al(OCH{sub 3}){sub x}(OSiH{sub 3}){sup -}{sub 1-x}, 2T, H{sub 2}Al(OCH{sub 3}){sub x}(OSiH{sub 3}){sup -}{sub 2-x}, 3T, Al(OCH3){sub x}(OSiH{sub 3}){sup -}{sub 4-x}, 5T] that mimic the charge sites in polyelectrolytes are calculated by ab initio molecular orbital methods at different levels of theory. At the HF/6-31G* level, the decrease in the sodium affinity due to the substitution of an OCH{sub 3} group by an OSiH{sub 3} group is about 8 kcal/mol in the 2T and 3T systems. In the 5T systems, the replacement of a sodium-coordinated OCH{sub 3} group by an OSiH{sub 3} group causes a decrease of 7 kcal/mol in the sodium affinity, while the substitution for a non-sodium-coordinated OCH{sub 3} group results in a 2.7 kcal/mol decrease. The lower sodium affinity indicates a weaker Coulombic interaction, suggesting an enhanced ionic conductivity with the substitution of carbon by silicon, consistent with experimental results. Natural bond orbital (NBO) analyses show that silicon-bonded oxygen atoms have smaller lone-pair dipole moments, resulting in a lower sodium affinity. The substitution of aluminum by boron leads to a higher sodium affinity, although the effect of replacing an OCH{sub 3} group by an OSiH{sub 3} group still reduces the sodium affinity. The effect of the sodium cation on the bond angles in these systems is also investigated.

  11. Computational studies of polyelectrolytes containing zeolitic fragments

    SciTech Connect

    Lee, Y.C.; Ratner, M.A.; Shriver, D.F. [Northwestern Univ., Evanston, IL (United States)] [Northwestern Univ., Evanston, IL (United States); Curtiss, L.A. [Argonne National Lab., IL (United States). Materials Science Div.] [Argonne National Lab., IL (United States). Materials Science Div.

    1999-08-05

    The structures and sodium affinities of a series of zeolitic fragments [H{sub 3}Al(OCH{sub 3}){sub x}(OSiH{sub 3}){sub 1{minus}x}{sup {minus}}, 2T, H{sub 2}Al(OCH{sub 3}){sub x}(OSiH{sub 3}){sub 2{minus}x}{sup {minus}}, Al(OCH{sub 3}){sub x}(OSiH{sub 3}){sub 4{minus}x}{sup {minus}}, 5T], that mimic the charge sites in polyelectrolytes are calculated by ab initio molecular orbital methods at different levels of theory. At the HF/6-31G{sup *} level, the decrease in the sodium affinity due to the substitution of an OCH{sub 3} group by an OSiH{sub 3} group is about 8 kcal/mol in the 2T and 3T systems. In the 5T systems, the replacement of a sodium-coordinated OCH{sub 3} group by an OSiH{sub 3} group causes a decrease of 7 kcal/mol in the sodium affinity, while the substitution for a non-sodium-coordinated OCH{sub 3} group results in a 2.7 kcal/mol decrease. The lower sodium affinity indicates a weaker Coulombic interaction, suggesting an enhanced ionic conductivity with the substitution of carbon by silicon, consistent with experimental results. Natural bond orbital (NBO) analyses show that silicon-bonded oxygen atoms have smaller lone-pair dipole moments, resulting in a lower sodium affinity. The substitution of aluminum by boron leads to a higher sodium affinity, although the effect of replacing an OCH{sub 3} group by an OSiH{sub 3} group still reduces the sodium affinity. The effect of the sodium cation on the bond angles in these systems is also investigated.

  12. Volatility of copper

    SciTech Connect

    Palmer, D.A.; Simonson, J.M.; Joyce, D.B.

    1996-08-01

    The relevant aqueous thermodynamics of copper and its oxides are evaluated and summarized with emphasis on solubility, hydrolysis, and complexation. The solubilities of metallic copper, solid cuprous and cupric oxides in steam measured by Pocock and Stewart in 1963 are discussed and the latter data are fitted in the form of established empirical equations and compared to other existing results. No other sources of data were found for the solubility of copper and cupric oxide in steam and even these data are very limited. Discussion of corresponding available solubility data on both oxide phases in liquid water is given. The possible effects of complexing agents are considered. A brief discussion is provided of the role of surface adsorption in determining the fate of dissolved copper in the boiler. 37 refs., 5 figs., 3 tabs.

  13. Canine models of copper toxicosis for understanding mammalian copper metabolism.

    PubMed

    Fieten, Hille; Leegwater, Peter A J; Watson, Adrian L; Rothuizen, Jan

    2012-02-01

    Hereditary forms of copper toxicosis exist in man and dogs. In man, Wilson's disease is the best studied disorder of copper overload, resulting from mutations in the gene coding for the copper transporter ATP7B. Forms of copper toxicosis for which no causal gene is known yet are recognized as well, often in young children. Although advances have been made in unraveling the genetic background of disorders of copper metabolism in man, many questions regarding disease mechanisms and copper homeostasis remain unanswered. Genetic studies in the Bedlington terrier, a dog breed affected with copper toxicosis, identified COMMD1, a gene that was previously unknown to be involved in copper metabolism. Besides the Bedlington terrier, a number of other dog breeds suffer from hereditary copper toxicosis and show similar phenotypes to humans with copper storage disorders. Unlike the heterogeneity of most human populations, the genetic structure within a purebred dog population is homogeneous, which is advantageous for unraveling the molecular genetics of complex diseases. This article reviews the work that has been done on the Bedlington terrier, summarizes what was learned from studies into COMMD1 function, describes hereditary copper toxicosis phenotypes in other dog breeds, and discusses the opportunities for genome-wide association studies on copper toxicosis in the dog to contribute to the understanding of mammalian copper metabolism and copper metabolism disorders in man. PMID:22147205

  14. 2D Zeolite Coatings: Langmuir-Schaefer Deposition of 3?nm Thick MFI Zeolite Nanosheets.

    PubMed

    Rangnekar, Neel; Shete, Meera; Agrawal, Kumar Varoon; Topuz, Berna; Kumar, Prashant; Guo, Qiang; Ismail, Issam; Alyoubi, Abdulrahman; Basahel, Sulaiman; Narasimharao, Katabathini; Macosko, Christopher W; Mkhoyan, K Andre; Al-Thabaiti, Shaeel; Stottrup, Benjamin; Tsapatsis, Michael

    2015-05-26

    Stable suspensions of zeolite nanosheets (3?nm thick MFI layers) were prepared in ethanol following acid treatment, which partially removed the associated organic structure-directing agent. Nanosheets from these suspensions could then be dispersed at the air-water interface and transferred to silicon wafers using Langmuir-Schaefer deposition. Using layer-by-layer deposition, control on coating thickness was demonstrated. In-plane X-ray diffraction (XRD) revealed that the deposited nanosheets contract upon calcination similar to bulk MFI crystals. Different methods for secondary growth resulted in preferentially oriented thin films of MFI, which had sub-12-nm thickness in certain cases. Upon calcination, there was no contraction detectable by in-plane XRD, indicating well-intergrown MFI films that are strongly attached to the substrate. PMID:25864539

  15. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    NASA Astrophysics Data System (ADS)

    Xingu-Contreras, E.; García-Rosales, G.; García-Sosa, I.; Cabral-Prieto, A.; Solache-Ríos, M.

    2015-05-01

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45? (2𝜃), inferring the presence of nanocrystals of Fe2B as identified from Mössbauer Spectroscopy. The size of these Fe2B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ? 95 %.

  16. DIFFUSION MEASUREMENTS DURING PERVAPORATION THROUGH A ZEOLITE MEMBRANE

    EPA Science Inventory

    An isotopic-transient technique was used to directly measure diffusion times of H2O, methanol, ethanol, 2-propanol, and acetone in pure and binary mixture feeds transporting through a zeolite membrane under steady-state pervaporation conditions. Diffusivities can be determ...

  17. Inelastic neutron scattering from tetramethylammonium cations occluded within zeolites

    SciTech Connect

    Brun, T.O.; Curtiss, L.A.; Iton, L.E.; Kleb, R.; Newsam, J.M.; Beyerlein, R.A.; Vaughan, D.E.W.

    1987-06-24

    The use of organic bases, for example, tetraalklylammonium hydroxides, and other organic reagents has greatly enhanced the scope of gel/solution synthesis routes to crystalline microporous materials such as zeolites. The role of these organic components, however, continues to be the topic of considerable debate. The organic components first modify the gel structural chemistry. The presence of tetramethylammonium (TMA) hydroxide, for example, promotes the formation of double four-ring units in silicate solutions. Occlusion of organic gel components in zeolite crystal structures, however, leads also to the concept of a templating effect in which the organic component provides a basis around which the developing zeolite cages form. The mechanism of this templating process remains somewhat ill defined and must, at least, be of variable specificity. The authors describe here the use of inelastic neutron scattering (INS) to measure TMA template torsional vibrations, vibrations that provide to be sensitive to the strength of the interaction between the template cation and the enclosing zeolite cage.

  18. Synthesis and Properties of Nano Zeolitic Imidazolate Frameworks

    Microsoft Academic Search

    Satish K. Nune; Praveen K. Thallapally; Alice Dohnalkova; Chongmin Wang; Jun Liu; Gregory J. Exarhos

    2010-01-01

    Nano sized zeolitic imidazolate frameworks [nZIF-8] with excellent chemical and thermal stability has been synthesized at room temperature by simple mixing of 2-methylimidazole and zinc nitrate hexahydrate in methanol\\/ 1% high molecular weight poly(diallyldimethylammonium chloride) solution for 24 hrs

  19. Synthesis and Properties of Nano Zeolitic Imidazolate Frameworks

    SciTech Connect

    Nune, Satish K.; Thallapally, Praveen K.; Dohnalkova, Alice; Wang, Chong M.; Liu, Jun; Exarhos, Gregory J.

    2010-07-21

    Nano sized zeolitic imidazolate frameworks [nZIF-8] with excellent chemical and thermal stability has been synthesized at room temperature by simple mixing of 2-methylimidazole and zinc nitrate hexahydrate in methanol/ 1% high molecular weight poly(diallyldimethylammonium chloride) solution for 24 hrs

  20. USE OF SYNTHETIC ZEOLITES FOR ARSENATE REMOVAL FROM POLLUTANT WATER

    EPA Science Inventory

    Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. In the present work, the potential use of a variety of synthetic zeolites for removal of arsenic from water below the current and proposed EPA MCL has been examined...

  1. ADSORPTION AND CATALYTIC DESTRUCTION OF TRICHLOROETHYLENE IN HYDROPHOBIC ZEOLITES

    EPA Science Inventory

    Several chromium exchanged ZSM-5 zeolites of varying SiO2/Al2O3 ratio were prepared and investigated for ambient (23 ?C) adsorption and subsequent oxidative destruction (250-400 ?C) of gaseous trichloroethylene (TCE, Cl2C=CHCl) in a humid air stream. With an increase in the SiO2...

  2. Use of synthetic zeolites for arsenate removal from pollutant water

    Microsoft Academic Search

    Siddhesh Shevade; Robert G. Ford

    2004-01-01

    Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. In the present work, the potential use of a variety of synthetic zeolites for removal of arsenic from water below the current and proposed EPA MCL has been examined at room temperature. Experiments have been conducted to examine the extent of arsenic

  3. Calibration analysis of zeolites by laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  4. Fenton Chemistry of FeIII Zeolitic Minerals Treated with

    E-print Network

    Dutta, Prabir K.

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

  5. [Denitrification water treatment with zeolite composite filter by intermittent operation].

    PubMed

    Qing, Cheng-Song; Bao, Tao; Chen, Tian-Hu; Chen, Dong; Xie, Jing-Jing

    2012-12-01

    The zeolite composite filters (ZCF) with the size of4-8 mm were prepared using raw zeolite (0.15-0.18 mm) as the main material and the cement as binder. After a combination of material characterizations, such as the void fraction, apparent density, compression strength and surface area, the optimal prepared conditions of composite filters were obtained as follow: weight ratio of m (zeolite): m (cement) = 7 : 3, curing for 15 d under the moisture condition and ambient temperature. Through upflow low-concentration ammonia nitrogen wastewater, ZCF filled in the experimental column was hung with the biological membrane. Thus, intermittent dynamic experiments were conducted, the intermittent operation cycle included adsorption, biological regeneration and drip washing. Until concentration of ammonia nitrogen was more than 2 mg x L(-1) of effluent standards, water in experiment column was firstly emptied, and then blast biological regeneration was conducted. After the filters were bathed with water, the zeolite adsorption-biological regeneration cycle was performed repeatedly. The experimental results show that under conditions of 24 h blast and 5 d of continuous operation period, ammonia nitrogen removal rate is up to 87.6% on average, total nitrogen removal rate reaches 51.2% on average. PMID:23379168

  6. Binary diffusion of unequal sized molecules in zeolites

    Microsoft Academic Search

    Narasimhan Sundaram; Ralph T Yang

    2000-01-01

    Multicomponent diffusivities in zeolites are predicted using the framework of the theory of irreversible thermodynamics, for which the information on equilibrium mixture adsorption isotherms is a critical requirement. Two thermodynamically consistent mixture isotherms, a multi-site Langmuir model and a modified Dubinin-type expansion facilitate quantification of the thermodynamic effect. In both these isotherms, saturation capacities of the species are allowed to

  7. Smart zeolites: New forms of tungsten and molybdenum oxides

    Microsoft Academic Search

    Geoffrey A. Ozin; R. A. Prokopowicz; S. Oezkar

    1992-01-01

    In this Account, the authors describe their recent research efforts involving the use of volatile hexacarbonylmolybdenum and -tungstem compounds, as precursors in the synthesis of highly organized assemblies of molecular dimension molybdenum and tungsten oxides, encapsulated within the diamond network of 13-[Angstrom] supercages found in zeolite Y. These assemblies are extremely uniform in terms of their nuclearity and structure, and

  8. Studies of photochemically and electrochemically driven electron transport in zeolites

    NASA Astrophysics Data System (ADS)

    Mallouk, T. E.

    1988-04-01

    Electron transfer reactions in zeolites and related solid-state materials are being studied. Some particular areas of study are: Electron transfer reactions of linked sensitizer-acceptor molecules. We have studied via laser flash photolysis transient absorbance the photochemistry of linked Ru(bpy)3--diquat molecules exchanged onto the outer surface of zeolite L powder. Electron-donor quenching of excited-state RuL3 complexes was also examined. We have studied electron transfer reactions between cyanometallate anions M(CN)8(sup 4 minus)(M = Mo,W), M(CN)6(sup 4 minus)(M = Fe,Os) and excited state ruthenium complexes. Quantum-size TiO2 in zeolite L was next examined. We are attempting to prepare systems in which the conduction band of an oxide semiconductor is used to convey electrons from a sensitizer to a catalyst within a zeolite L particle. Internal platinization of pillared clays. We have photoplatinized dispersed Na(+) montmorillonite, using PtCl6(sup 2 minus) as the platinum source, and then pillared the clay with Al(OH)2C1 solutions. We are currently investigating the size and charge selectivity of these catalytic materials.

  9. Desulfurization of Transportation Fuels with Zeolites Under Ambient Conditions

    Microsoft Academic Search

    Ralph T. Yang; Arturo J. Hernández-Maldonado; Frances H. Yang

    2003-01-01

    Deep desulfurization of transportation fuels (gasoline, diesel, and jet fuels) is being mandated by U.S. and foreign governments and is also needed for future fuel cell applications. However, it is extremely difficult and costly to achieve with current technology, which requires catalytic reactors operated at high pressure and temperature. We show that Cu+ and Ag+ zeolite Y can adsorb sulfur

  10. Catalase-like activity studies of the manganese(II) adsorbed zeolites

    NASA Astrophysics Data System (ADS)

    ?içek, Ekrem; Dede, Bülent

    2013-12-01

    Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

  11. Zeolite in horizontal permeable reactive barriers for artificial groundwater recharge

    NASA Astrophysics Data System (ADS)

    Leal, María; Martínez-Hernández, Virtudes; Lillo, Javier; Meffe, Raffaella; de Bustamante, Irene

    2013-04-01

    The Spanish Water Reuse Royal Decree 1620/2007 considers groundwater recharge as a feasible use of reclaimed water. To achieve the water quality established in the above-mentioned legislation, a tertiary wastewater treatment is required. In this context, the infiltration of effluents generated by secondary wastewater treatments through a Horizontal Permeable Reactive Barrier (HPRB) may represent a suitable regeneration technology. Some nutrients (phosphate and ammonium) and some Pharmaceutical and Personal Care Products (PPCPs) are not fully removed in conventional wastewater treatment plants. To avoid groundwater contamination when effluents of wastewater treatments plants are used in artificial recharge activities, these contaminants have to be removed. Due to its sorption capacities, zeolite is among the most used reactive materials in Permeable Reactive Barrier (PRB). Therefore, the main goal of this study is to evaluate the zeolite retention effectiveness of nutrients and PPCPs occurring in treated wastewater. Batch sorption experiments using synthetic wastewater (SWW) and zeolite were performed. A 1:4 zeolite/SWW ratio was selected due to the high sorption capacity of the reactive material.The assays were carried out by triplicate. All the bottles containing the SWW-zeolite mixture were placed on a mechanical shaker during 24 hours at 140 rpm and 25 °C. Ammonium and phosphate, as main nutrients, and a group of PPCPs were selected as compounds to be tested during the experiments. Nutrients were analyzed by ion chromatography. For PPCPs determination, Solid Phase Extraction (SPE) was applied before their analysis by liquid chromatography-mass spectrometry time of flight (LC-MS/ TOF). The experimental data were fitted to linearized Langmuir and Freundlich isotherm equations to obtain sorption parameters. In general, Freundlich model shows a greater capability of reproducing experimental data. To our knowledge, sorption of the investigated compounds on zeolite has rarely been addressed and this holds true especially for PPCPs. Therefore, the obtained results will be useful for the design and characterization of those HPRBs in which zeolite will be employed to regenerate treated wastewater for artificial recharge activities.

  12. Catalytic dehydrocondensation of methane towards benzene and naphthalene on transition metal supported zeolite catalysts: templating role of zeolite micropores and characterization of active metallic sites

    Microsoft Academic Search

    Yuying Shu; Masaru Ichikawa

    2001-01-01

    The catalytic dehydrocondensation of methane to benzene and naphthalene with a bulky of hydrogen on transition metal supported zeolite catalysts is one of strategies for the catalytic conversion of methane and a challenging topic in heterogeneous catalysis. This paper is dealt with the current progress in catalytic dehydrocondensation of methane towards benzene and naphthalene on transition metal supported zeolite catalysts,

  13. Bacterial Killing by Dry Metallic Copper Surfaces?

    PubMed Central

    Santo, Christophe Espírito; Lam, Ee Wen; Elowsky, Christian G.; Quaranta, Davide; Domaille, Dylan W.; Chang, Christopher J.; Grass, Gregor

    2011-01-01

    Metallic copper surfaces rapidly and efficiently kill bacteria. Cells exposed to copper surfaces accumulated large amounts of copper ions, and this copper uptake was faster from dry copper than from moist copper. Cells suffered extensive membrane damage within minutes of exposure to dry copper. Further, cells removed from copper showed loss of cell integrity. Acute contact with metallic copper surfaces did not result in increased mutation rates or DNA lesions. These findings are important first steps for revealing the molecular sensitive targets in cells lethally challenged by exposure to copper surfaces and provide a scientific explanation for the use of copper surfaces as antimicrobial agents for supporting public hygiene. PMID:21148701

  14. Effects of ultrasonic treatment on zeolite NaA synthesized from by-product silica.

    PubMed

    Vai?iukynien?, Danut?; Kantautas, Aras; Vaitkevi?ius, Vitoldas; Jakevi?ius, Leonas; Rudžionis, Žymantas; Paškevi?ius, Mantas

    2015-11-01

    The synthesis of zeolite NaA from silica by-product was carried out in the presence of 20kHz ultrasound at room temperature. Zeolites obtained in this type of synthesis were compared to zeolites obtained by performing conventional static syntheses under similar conditions. The sonication effects on zeolite NaA synthesis were characterized by phase identification, crystallinity etc. The effects of different parameters such as crystallization time and initial materials preparation methods on the crystallinity and morphology of the synthesized zeolites were investigated. The final products were characterized by XRD and FT-IR. It was possible to obtain crystalline zeolite NaA from by-product silica in the presence of ultrasound. PMID:26186874

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

    SciTech Connect

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

    2005-06-01

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

  16. The Ameliorative Effect of Artificial Zeolite on Barley under Saline Conditions

    NASA Astrophysics Data System (ADS)

    Al-Busaidi, A.; Yamamoto, T.; Irshad, M.

    This investigation was aimed to evaluate the effects of zeolite in conjunction with seawater irrigation on barley (Hordeum vulgare L.) growth and salt composition of soil. A sand dune soil was amended with Ca-type zeolite at the rate of 1 and 5% and the seawater was diluted up to the electrical conductivity of 3 and 16 dS mG1. Present results showed that zeolite application significantly increased water holding capacity of the soil and accumulated more salts. The zeolite mixed soils improved plant growth compared to the un-amended control. Higher saline water significantly suppressed the growth of barley than the water with low salinity. The restricted plant growth due to the effects of specific ion or Na+/Ca2+ imbalance may be ameliorated using Ca-type zeolite. We may conclude that soil amendment with zeolite could alleviate the adverse effects of salts on plants following irrigation with higher saline water.

  17. XAFS Study on TiO2 Photocatalyst Loaded on Zeolite Synthesized from Steel Slag

    NASA Astrophysics Data System (ADS)

    Kuwahara, Yasutaka; Ohmichi, Tetsutaro; Mori, Kosuke; Katayama, Iwao; Yamashita, Hiromi

    2007-02-01

    The convenient route for the synthesis of Y-zeolites by utilizing steel slag as a material source was developed. Through hydrothermal treatment, well-crystallized Y-zeolite was obtained. We also synthesized TiO2-loaded Y-zeolites by an impregnation method. The structure of titanium oxide species highly dispersed on the zeolite, which couldn't be detected by XRD patterns, was investigated by XAFS analysis. Photocatalytic activity for decomposition of 2-propanol in liquid phase was found to be enhanced by the hydrophobic surface property of zeolite. It has been demonstrated that the zeolite synthesized from steel slag would be applicable as a promising support of TiO2 photocatalyst.

  18. ?-? interaction of aromatic groups in amphiphilic molecules directing for single-crystalline mesostructured zeolite nanosheets

    NASA Astrophysics Data System (ADS)

    Xu, Dongdong; Ma, Yanhang; Jing, Zhifeng; Han, Lu; Singh, Bhupendra; Feng, Ji; Shen, Xuefeng; Cao, Fenglei; Oleynikov, Peter; Sun, Huai; Terasaki, Osamu; Che, Shunai

    2014-06-01

    One of the challenges in material science has been to prepare macro- or mesoporous zeolite. Although examples of their synthesis exist, there is a need for a facile yet versatile approach to such hierarchical structures. Here we report a concept for designing a single quaternary ammonium head amphiphilic template with strong ordered self-assembling ability through ?-? stacking in hydrophobic side, which stabilizes the mesostructure to form single-crystalline mesostructured zeolite nanosheets. The concept is demonstrated for the formation of a new type of MFI (zeolite framework code by International Zeolite Association) nanosheets joined with a 90° rotational boundary, which results in a mesoporous zeolite with highly specific surface area even after calcination. Low binding energies for this self-assembling system are supported by a theoretical analysis. A geometrical matching between the arrangement of aromatic groups and the zeolitic framework is speculated for the formation of single-crystalline MFI nanosheets.

  19. Role of copper transporters in copper homeostasis234

    PubMed Central

    Prohaska, Joseph R

    2009-01-01

    Copper is a redox active metal that is essential for biological function. Copper is potentially toxic; thus, its homeostasis is carefully regulated through a system of protein transporters. Copper is taken up across the lumen surface of the small intestinal microvilli as cuprous ion by Ctr1. Cupric ion may also be taken up, but those processes are less well understood. Within the cell, intestinal as well as others, copper is escorted to specific compartments by metallo-chaperones. One, CCS, donates copper to superoxide dismutase. Another, COX17, delivers copper to additional chaperones within the mitochondria for synthesis of cytochrome c oxidase. A third chaperone, Atox1, delivers copper to the secretory pathway by docking with 2 P-type ATPases. One, ATP7A, is the protein nonfunctional in Menkes disease. This protein is required for cuproenzyme biosynthesis, and in the enterocyte it is required for copper efflux to portal blood. The second, ATP7B, predominantly expressed in liver, is required for copper metallation of ceruloplasmin and biliary copper excretion. Mutations in ATP7B lead to Wilson disease. Additional intracellular hepatic copper-binding proteins COMMD1 (copper metabolism MURR1 domain) and XIAP (X-linked inhibitor of apoptosis protein) may also be required for excretion. Other proteins involved in copper homeostasis may include metallothionein and amyloid precursor protein. Plasma protein transport of copper from the intestine to liver and in systemic circulation probably includes both albumin and ?2-macroglobulin. Changes in the expression of copper “transporters” may be useful to monitor copper status of humans, provided a suitable cell type can be sampled. PMID:18779302

  20. Desorption process of copper chlorides from copper surface

    Microsoft Academic Search

    Atsushi Hibi; Akio Susa; Mitsuo Koshi

    2008-01-01

    Gaseous copper chlorides can be employed as precursors in a newly developed Cu-CVD method called metal chloride reduction-chemical vapor deposition (MCR-CVD). More than one species exists in the gas phase of copper chloride. We studied the gas phase composition of copper chlorides generated by etching of copper surface by electron impact-mass spectrometry. The composition of gaseous species can change because

  1. Selective divalent copper chelation for the treatment of diabetes mellitus.

    PubMed

    Cooper, G J S

    2012-01-01

    Oxidative stress and mitochondrial dysfunction have been identified by many workers as key pathogenic mechanisms in ageing-related metabolic, cardiovascular and neurodegenerative diseases (for example diabetes mellitus, heart failure and Alzheimer's disease). However, although numerous molecular mechanisms have been advanced to account for these processes, their precise nature remains obscure. This author has previously suggested that, in such diseases, these two mechanisms are likely to occur as manifestations of a single underlying disturbance of copper regulation. Copper is an essential but highly-toxic trace metal that is closely regulated in biological systems. Several rare genetic disorders of copper homeostasis are known in humans: these primarily affect various proteins that mediate intracellular copper transport processes, and can lead either to tissue copper deficiency or overload states. These examples illustrate how impaired regulation of copper transport pathways can cause organ damage and provide important insights into the impact of defects in specific molecular processes, including those catalyzed by the copper-transporting ATPases, ATP7A (mutated in Menkes disease), ATP7B (Wilson's disease), and the copper chaperones such as those for cytochrome c oxidase, SCO1 and SCO2. In diabetes, impaired copper regulation manifests as elevations in urinary CuII excretion, systemic chelatable-CuII and full copper balance, in increased pro-oxidant stress and defective antioxidant defenses, and in progressive damage to the blood vessels, heart, kidneys, retina and nerves. Linkages between dysregulated copper and organ damage can be demonstrated by CuII-selective chelation, which simultaneously prevents/reverses both copper dysregulation and organ damage. Pathogenic structures in blood vessels that contribute to binding and localization of catalytically-active CuII probably include advanced glycation end products (AGEs), as well as atherosclerotic plaque: the latter probably undergoes AGE-modification itself. Defective copper regulation mediates organ damage through two general processes that occur simultaneously in the same individual: elevation of CuII-mediated pro-oxidant stress and impairment of copper-catalyzed antioxidant defence mechanisms. This author has proposed that diabetes-evoked copper dysregulation is an important new target for therapeutic intervention to prevent/reverse organ damage in diabetes, heart failure, and neurodegenerative diseases, and that triethylenetetramine (TETA) is the first in a new class of anti-diabetic molecules, which function by targetting these copper-mediated pathogenic mechanisms. TETA prevents tissue damage and causes organ regeneration by acting as a highly-selective CuII chelator which suppresses copper-mediated oxidative stress and restores anti-oxidant defenses. My group has employed TETA in a comprehensive programme of nonclinical studies and proof-of-principle clinical trials, thereby characterizing copper dysregulation in diabetes and identifying numerous linked cellular and molecular mechanisms though which TETA exerts its therapeutic actions. Many of the results obtained in nonclinical models with respect to the molecular mechanisms of diabetic organ damage have not yet been replicated in patients' tissues so their applicability to the human disease must be considered as inferential until the results of informative clinical studies become available. Based on evidence from the studies reviewed herein, trientine is now proceeding into the later stages of pharmaceutical development for the treatment of heart failure and other diabetic complications. PMID:22455587

  2. LABORATORY EXPERIMENT 7 Determination of Copper in Copper Alloys

    E-print Network

    Nazarenko, Alexander

    LABORATORY EXPERIMENT 7 Determination of Copper in Copper Alloys Two procedures for Cu determination in the same alloy sample will be used. Both are based on Cu2+ reduction. I. The Electrogravimetric Determination of Copper in Alloy A convenient example of an electrogravimetric method of analysis

  3. Hydrothermal synthesis of NaA zeolite membrane together with microwave heating and conventional heating

    Microsoft Academic Search

    Aisheng Huang; Weishen Yang

    2007-01-01

    Uniform and dense NaA zeolite membrane was prepared by hydrothermal synthesis method together with microwave heating and conventional heating. The properties of the as-synthesized zeolite membrane were investigated by XRD, SEM and pervaporation evaluation for dehydration of 95 wt.% isopropanol\\/water mixture at 343 K, respectively. After microwave heating, the ?-Al2O3 support surface was covered with homogeneous zeolite nuclei, which facilitated to form

  4. Effect of some additives on synthesis of zeolite from coal fly ash

    Microsoft Academic Search

    Deyi Wu; Bohua Zhang; Li Yan; Hainan Kong; Xinze Wang

    2006-01-01

    Hydrothermal conversion of fly ash into zeolites was conducted and the effects of the addition of sodium halide and waste solutions produced after zeolitization of fly ash, as well as the adjustment of the Si\\/Al ratio prior to synthesis process on the formation and cation exchange capacity (CEC) of zeolite product were evaluated. Both the addition of NaCl and NaF

  5. Microwave Versus Conventional-Hydrothermal Synthesis of NaY Zeolite

    Microsoft Academic Search

    Hiroaki Katsuki; Sachiko Furuta; Sridhar Komarneni

    2001-01-01

    This paper focuses on the synthesis of NaY zeolite crystals by using microwave-hydrothermal (M-H) processing. NaY zeolites were synthesized from colloidal silica, sodium aluminate, sodium hydroxide and deionized water at 100°C, and some properties were studied. NaY zeolite crystals with high surface area, in the range of 439 to 716 m2\\/g, have been prepared at 100°C for 1 to 3

  6. Microwave-Driven Zeolite?Guest Systems Show Athermal Effects from Nonequilibrium Molecular Dynamics

    Microsoft Academic Search

    Cristian Blanco; Scott M. Auerbach

    2002-01-01

    simulations. We studied industrially important zeolites that represent extremes of high charge (NaY) and low charge (de-aluminated Y (DAY) and silicalite) materials. We also studied guest molecules that represent extremes of polar (methanol) and nonpolar (benzene) species. We performed equilibrium molecular dynamics (MD) and nonequilibrium MD (NEMD) simulations on bare zeolites, and on zeolite-guest systems with single-component guest phases as

  7. Alkylation of benzene with ethylene over faujasite zeolite investigated by the ONIOM method

    Microsoft Academic Search

    Supawadee Namuangruk; Piboon Pantu; Jumras Limtrakul

    2004-01-01

    The alkylation of benzene with ethylene over faujasite zeolite has been investigated using an 84T cluster of faujasite zeolite serving as a nanometer-sized chemical reactor modeled by the ONIOM3 (MP2\\/6-311++G(d,p):HF\\/6-31G(d):UFF) method, which gives accurate adsorption energies for the reactants and the product, indicating the accuracy of the model in representing interactions between the adsorbates and the zeolite. The computed adsorption

  8. Preparation of highly selective zeolite ZSM-5 membranes by a post-synthetic coking treatment

    Microsoft Academic Search

    Yushan Yan; Mark E. Davis; George R. Gavalas

    1997-01-01

    Zeolite ZSM-5 membranes with high n-butane:isobutane selectivities, e.g., 322 at 185°C, are obtained by a selective deposition of coke into non-zeolitic pores. The zeolite membranes are prepared by in situ crystallization on either bare porous ?-Al2O3 support disks or disks that are pretreated to include a diffusion barrier. The post-synthetic coking treatment is accomplished by impregnating these membranes with liquid

  9. Synthesis of zeolite from coal fly ashes with different silica–alumina composition

    Microsoft Academic Search

    Miki Inada; Yukari Eguchi; Naoya Enomoto; Junichi Hojo

    2005-01-01

    Coal fly ashes can be converted into zeolites by hydrothermal alkaline treatment. This study focuses on the effect of Si\\/Al molar ratio of the fly ash source on the type of formed zeolite, which also is affected by the alkaline condition. The fly ashes were mixed with an aqueous NaOH solution and hydrothermally treated at about 100°C. Zeolite Na–P1 and\\/or

  10. A solid-state nuclear magnetic resonance study of the reactions of propene on HY zeolite

    E-print Network

    Oshiro, Irene Sueko

    1988-01-01

    , as denoted by arrows C CP/MAS spectrum of propene-2- C 13 adsorbed on HY zeolite at room temperature 10 The polymerization reaction proposed in reference 13 for the adsorption of propene on HY zeolite The Bloch decay pulse sequence in NMR experiments... 12 18 The cross polarization pulse sequence for dilute nuclei . . . . . . . . . . . . . . . . . . . . . 22 The CAVERN apparatus and rotor used in low temperature adsorptions 26 C spectra of propene adsorbed on HY zeolite . 31 C MAS NMR spectra...

  11. An investigation of Knoevenagel condensation reaction in microreactors using a new zeolite catalyst

    Microsoft Academic Search

    Xiongfu Zhang; Emily Sau Man Lai; Rosa Martin-Aranda; King Lun Yeung

    2004-01-01

    New basic zeolite catalysts obtained by grafting amino groups onto NaX and CsNaX zeolites exhibit excellent catalytic activities for Knoevenagel condensation reaction between benzaldehyde and ethyl cyanoacetate (ECA), ethyl acetoacetate (EAA) and diethyl malonate (DEM). The CsNaX-NH2 catalyst also displays higher conversion compared to aminopropylated MCM-41. Knoevenagel condensation reaction in a CsNaX zeolite microreactor performed better than the traditional packed

  12. Physicochemical properties and activity of Mo-containing zeolite catalysts of nonoxidative conversion of methane

    NASA Astrophysics Data System (ADS)

    Korobitsyna, L. L.; Arbuzova, N. V.; Vosmerikov, A. V.

    2013-06-01

    High-silica zeolites of ZSM-5 structural type were synthesized using various structure-forming additives and without them. Mo-containing catalytic systems were prepared on the basis of these zeolites. Their physicochemical properties and activity in the course of the nonoxidative conversion of methane were studied. The Mo/ZSM-5 catalyst obtained on the basis of zeolite synthesized with hexamethylenediamine showed high aromatizing activity and stability.

  13. Growth and bone development in weanling quarter horses fed diets supplemented with sodium zeolite-A 

    E-print Network

    Frey, Kimberly Suzanne

    1991-01-01

    - supplemented, for twelve days. After this time, the deficient group had no increase in dry weight and the supplemented group had an increase of 23%. At the end of eight days, the 16 supplemented bones had a 140% increase in collagen content over... of osteogenic cells, especially osteoblasts, and silicon mainly influences bone growth through collagen synthesis (1982). Sodium Zeolite-A Sodium zeolite-A (SZA) may prove to be a beneficial source of bioavailable silicon. Zeolites are a group of naturally...

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

    Microsoft Academic Search

    C. Colella; Piazza Ie; V. Tecchio

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

  15. Steam promoted mesoporosity in USY zeolites: structural properties and 1,2,4-TMB reactivity

    Microsoft Academic Search

    G Tonetto; M. L Ferreira; H de Lasa

    2004-01-01

    This work addresses the potential effects of steaming in the case of dealumination of Y zeolites. With this end, the interaction between 1,2,4-trimethylbenzene (1,2,4-TMB) and ultrastable Y zeolite (USY) is analyzed. The zeolite is modeled using the complete exposed USY structure of one unit cell constituted by eight sodalite cages, 16 hexagonal prisms bridging the sodalite cages and the formed

  16. Catalytic oxidation of volatile organic compounds (VOCs) mixture (isopropanol\\/ o-xylene) on zeolite catalysts

    Microsoft Academic Search

    R. Beauchet; P. Magnoux; J. Mijoin

    2007-01-01

    The catalytic oxidation of isopropanol and o-xylene alone and in mixture was investigated over basic zeolites (CsX and NaX) and an acidic zeolite (HY). For a given temperature, the conversion of VOCs mixture into CO2 increases with the basicity of the zeolite. Results show that VOCs are oxidized through a basic mechanism over NaX, and through an acidic mechanism over

  17. Equilibrium and kinetic modeling of adsorptive sulfur removal from gasoline by synthesized Ce–Y zeolite

    Microsoft Academic Search

    Maryam Montazerolghaem; Amir Rahimi; Fakhry Seyedeyn-Azad

    2010-01-01

    In this research, the adsorption of a model sulfur compound, thiophene, from a simulated gasoline onto Ce–Y zeolite in pellet and powder forms was investigated. For this purpose, zeolite Na–Y was synthesized, and Ce–Y zeolite was prepared via solid-state ion-exchanged (SSIE) method. Adsorptive desulfurization of model gasoline was conducted in a batch reactor at ambient conditions to evaluate the equilibrium

  18. Pervaporation performance of PDMS-Ni 2+Y zeolite hybrid membranes in the desulfurization of gasoline

    Microsoft Academic Search

    Ben Li; Dan Xu; Zhongyi Jiang; Xiongfei Zhang; Wanpeng Liu; Xiao Dong

    2008-01-01

    PDMS-Ni2+Y zeolite hybrid membranes were fabricated and used for the pervaporation removal of thiophene from model gasoline system. The structural morphology, mechanical stability, crystallinity, and free volume characteristics of the hybrid membranes were systematically investigated. Molecular dynamics simulation was employed to calculate the diffusion coefficients of small penetrants in the polymer matrix and the zeolite. The effect of Ni2+Y zeolite

  19. Ceruloplasmin, copper ions, and angiogenesis.

    PubMed

    Raju, K S; Alessandri, G; Ziche, M; Gullino, P M

    1982-11-01

    The ability to induce new formation of capillaries in the cornea was tested for ceruloplasmin, the copper carrier of serum, for fragments of the ceruloplasmin molecule with and without copper, for heparin, and for glycyl-L-histidyl-L-lysine, bound or not bound to copper ions. Male or female 2- to 3-kg New Zealand White rabbits were used. These experiments were prompted by the previous observation of copper accumulation in the cornea during angiogenesis and by the inability of copper-deficient rabbits to mount an angiogenic response. The results showed that the three different molecules were all able to induce angiogenesis provided that they were bound to copper. Fragments of the ceruloplasmin molecule also induced angiogenesis but only when copper was bound to the peptides. The data are interpreted to indicate that copper ions are involved in the sequence of events leading to angiogenesis and that the carrier molecules may be of quite a different nature. PMID:6182332

  20. Exploring for Copper Deposits

    NSDL National Science Digital Library

    2007-02-11

    In this activity, students assume the role of a geologist prospecting for copper deposits. From the background material, they will learn what ore deposits are and some important factors in their origin; and learn about a type of ore deposit known as a porphyry copper deposit. They will plot data from a table onto maps and use a geologic map, a soil geochemistry map, and a sediment geochemistry map to help locate the porphyry copper deposit. As a result of this activity, the students will be able to calculate an ore grade and determine whether or not an ore deposit is economically profitable based on its grade, size, and production costs. Worksheets and data tables are included.

  1. Silver confined within zeolite EMT nanoparticles: preparation and antibacterial properties

    NASA Astrophysics Data System (ADS)

    Dong, B.; Belkhair, S.; Zaarour, M.; Fisher, L.; Verran, J.; Tosheva, L.; Retoux, R.; Gilson, J.-P.; Mintova, S.

    2014-08-01

    The preparation of pure zeolite nanocrystals (EMT-type framework) and their silver ion-exchanged (Ag+-EMT) and reduced silver (Ag0-EMT) forms is reported. The template-free zeolite nanocrystals are stabilized in water suspensions and used directly for silver ion-exchange and subsequent chemical reduction under microwave irradiation. The high porosity, low Si/Al ratio, high concentration of sodium and ultrasmall crystal size of the EMT-type zeolite permitted the introduction of a high amount of silver using short ion-exchange times in the range of 2-6 h. The killing efficacy of pure EMT, Ag+-EMT and Ag0-EMT against Escherichia coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag+-EMT and Ag0-EMT). The Ag0-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag+-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not viable considering the complexity of preparation steps.The preparation of pure zeolite nanocrystals (EMT-type framework) and their silver ion-exchanged (Ag+-EMT) and reduced silver (Ag0-EMT) forms is reported. The template-free zeolite nanocrystals are stabilized in water suspensions and used directly for silver ion-exchange and subsequent chemical reduction under microwave irradiation. The high porosity, low Si/Al ratio, high concentration of sodium and ultrasmall crystal size of the EMT-type zeolite permitted the introduction of a high amount of silver using short ion-exchange times in the range of 2-6 h. The killing efficacy of pure EMT, Ag+-EMT and Ag0-EMT against Escherichia coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag+-EMT and Ag0-EMT). The Ag0-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag+-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not viable considering the complexity of preparation steps. Electronic supplementary information (ESI) available: Zeta potential data of Ag-EMT suspensions, pore-size distributions and antibacterial data for Ag-EMT 2 h samples. See DOI: 10.1039/c4nr03169e

  2. Agricultural soils spiked with copper mine wastes and copper concentrate: implications for copper bioavailability and bioaccumulation.

    PubMed

    Ginocchio, Rosanna; Sánchez, Pablo; de la Fuente, Luz María; Camus, Isabel; Bustamante, Elena; Silva, Yasna; Urrestarazu, Paola; Torres, Juan C; Rodríguez, Patricio H

    2006-03-01

    A better understanding of exposure to and effects of copper-rich pollutants in soils is required for accurate environmental risk assessment of copper. A greenhouse experiment was conducted to study copper bioavailability and bioaccumulation in agricultural soils spiked with different types of copper-rich mine solid wastes (copper ore, tailing sand, smelter dust, and smelter slag) and copper concentrate. A copper salt (copper sulfate, CuSO4) that frequently is used to assess soil copper bioavailability and phytotoxicity also was included for comparison. Results showed that smelter dust, tailing sand, and CuSO4 are more likely to be bioavailable and, thus, toxic to plants compared with smelter slag, concentrate, and ore at equivalent total copper concentrations. Differences may be explained by intrinsic differences in copper solubilization from the source materials, but also by their capability to decrease soil pH (confounding effect). The copper toxicity and bioaccumulation in plants also varied according to soil physicochemical characteristics (e.g., pH and total organic carbon) and the available levels of plant nutrients, such as nitrogen, phosphorus, and potassium. Chemistry/mineralogy of mine materials, soil/pore-water chemistry, and plant physiological status thus should be integrated for building adequate models to predict phytotoxicity and environmental risk of copper. PMID:16566155

  3. Facile synthesis of hollow zeolite microspheres through dissolution-recrystallization procedure in the presence of organosilanes

    NASA Astrophysics Data System (ADS)

    Tao, Haixiang; Ren, Jiawen; Liu, Xiaohui; Wang, Yanqin; Lu, Guanzhong

    2013-04-01

    Hollow zeolite microspheres have been hydrothermally synthesized in the presence of organosilanes via a dissolution-recrystallization procedure. In the presence of organosilanes, zeolite particles with a core/shell structure formed at the first stage of hydrothermal treatment, then the core was consumed and recrystallized into zeolite framework to form the hollow structure during the second hydrothermal process. The influence of organosilanes was discussed, and a related dissolution-recrystallization mechanism was proposed. In addition, the hollow zeolite microspheres exhibited an obvious advantage in catalytic reactions compared to conventional ZSM-5 catalysts, such as in the alkylation of toluene with benzyl chloride.

  4. Photocatalytic degradation of benzene on zeolite-incorporated TiO2 film.

    PubMed

    Hisanaga, Teruaki; Tanaka, Keiichi

    2002-08-01

    Zeolite powder was incorporated into the TiO2 film. Their photoactivities were evaluated for the gas phase degradation of benzene. Seven zeolite samples were used in this study and each enhanced the photocatalytic degradation. Humidity in the gas sample increased the degradation, but suppressed the adsorption of benzene to the TiO2 film. It was noted that the photoactivity was inversely proportional to the silica/alumina ratio of zeolite, whereas adsorption increased with this ratio. It was suggested that the adsorption of water onto zeolite contributes to the enhancement of benzene degradation. PMID:12137993

  5. Ligand exchange photochemistry of iodopentaamminerhodium (III) in a sodium/hydrogen Y type zeolite

    E-print Network

    Camara, Michael Joseph

    1981-01-01

    of the zeolite resulted in a lower value for the quantum yield of 0. 20+0. 07. The ammonia produced by this reaction was traoped within the zeolite as ammonium ious and semi-quantitatively analyzed by infrared spectroscopy. The rate was observed to fall off... for infrared study. Infrared spectrum of the ammonium ion band at -1 1450 cm and the zeolite background Calibration graph of ammonium ion concentration versus infrared absorption Correlation of the actual thickness of wafers of 33 38 41 43 zeolite...

  6. December 200 Copper Acquisition by

    E-print Network

    Fischlin, Andreas

    December 200 Copper Acquisition by Methanotrophic Bacteria 7 Term Paper HS2007 Major. One is soluble in the cytoplasm and the other is bound to the membrane. Since the expression of copper containing pMMO depends on copper availability it is supposed that some methanotrophs have developed

  7. HEALTH MATTERS Copper T IUD

    E-print Network

    Yener, Aylin

    T IUD? · This is a highly effective type of birth control. · The Copper T IUD does not contain hormones or interact with medicines. · You don't have to think about birth control every day or every time you have sex expensive methods of birth control. What are the downsides of using the Copper T IUD? · The Copper T IUD

  8. SOURCES OF COPPER AIR EMISSIONS

    EPA Science Inventory

    The report gives results of a study to update estimates of atmospheric emissions of copper and copper compounds in the U.S. Source categories evaluated included: metallic minerals, primary copper smelters, iron and steel making, combustion, municipal incineration, secondary coppe...

  9. Dynamic Nuclear Polarization NMR Enables the Analysis of Sn-Beta Zeolite Prepared with Natural Abundance [superscript 119]Sn Precursors

    E-print Network

    Gunther, William R.

    The catalytic activity of tin-containing zeolites, such as Sn-Beta, is critically dependent on the successful incorporation of the tin metal center into the zeolite framework. However, synchrotron-based techniques or ...

  10. Exceptional chemical and thermal stability of zeolitic imidazolate frameworks

    PubMed Central

    Park, Kyo Sung; Ni, Zheng; Côté, Adrien P.; Choi, Jae Yong; Huang, Rudan; Uribe-Romo, Fernando J.; Chae, Hee K.; O’Keeffe, Michael; Yaghi, Omar M.

    2006-01-01

    Twelve zeolitic imidazolate frameworks (ZIFs; termed ZIF-1 to -12) have been synthesized as crystals by copolymerization of either Zn(II) (ZIF-1 to -4, -6 to -8, and -10 to -11) or Co(II) (ZIF-9 and -12) with imidazolate-type links. The ZIF crystal structures are based on the nets of seven distinct aluminosilicate zeolites: tetrahedral Si(Al) and the bridging O are replaced with transition metal ion and imidazolate link, respectively. In addition, one example of mixed-coordination imidazolate of Zn(II) and In(III) (ZIF-5) based on the garnet net is reported. Study of the gas adsorption and thermal and chemical stability of two prototypical members, ZIF-8 and -11, demonstrated their permanent porosity (Langmuir surface area = 1,810 m2/g), high thermal stability (up to 550°C), and remarkable chemical resistance to boiling alkaline water and organic solvents. PMID:16798880

  11. GREEN CHEMISTRY. Shape-selective zeolite catalysis for bioplastics production.

    PubMed

    Dusselier, Michiel; Van Wouwe, Pieter; Dewaele, Annelies; Jacobs, Pierre A; Sels, Bert F

    2015-07-01

    Biodegradable and renewable polymers, such as polylactic acid, are benign alternatives for petrochemical-based plastics. Current production of polylactic acid via its key building block lactide, the cyclic dimer of lactic acid, is inefficient in terms of energy, time, and feedstock use. We present a direct zeolite-based catalytic process, which converts lactic acid into lactide. The shape-selective properties of zeolites are essential to attain record lactide yields, outperforming those of the current multistep process by avoiding both racemization and side-product formation. The highly productive process is strengthened by facile recovery and practical reactivation of the catalyst, which remains structurally fit during at least six consecutive reactions, and by the ease of solvent and side-product recycling. PMID:26138977

  12. Mechanism of the thermal decomposition of tetraethylammonium in zeolite {beta}

    SciTech Connect

    Bourgeat-Lami, E.; Di Renzo, F.; Fajula, F. [CNRS, ENSCM, Montpellier (France)] [and others

    1992-04-30

    The mechanism of the thermal decomposition of tetraethylammonium (TEA) in zeolite {beta} has been investigated under air and argon atmosphere using a combined technique of thermogravimetric analysis and mass spectrometry. The nature of the volatile products and the characterization of the solid after each thermal phenomenon shows that all TEA species, occluded ion pairs and counteranions, decompose into triethylamine and ethylene in a single step, in the temperature range 200-350{degrees}C. The amine readsorbs on the acidic sites of the zeolite and, as the temperature is increased, decomposes into lighter amines by sequential Hofmann elimination reactions. Part of the ethylene also reacts with the acid sites yielding aliphatic and aromatic hyrocarbons. Complete desorption of the organic species form the structure requires a temperature higher than 500 {degrees}C. 14 refs., 5 figs., 8 tabs.

  13. Nonequilibrium Diffusion in Zeolites due to Deterministic Hamiltonian Chaos

    Microsoft Academic Search

    Dmitry I. Kopelevich; Hsueh-Chia Chang

    1999-01-01

    We show that diffusionlike transport of a spherical sorbate molecule through a zeolite crystal can be driven by deterministic chaos instead of thermal stochastic noise when the sorbate and crystal do not equilibrate. Using a random-phase approximation for the resulting Arnold diffusion and a boundary-layer analysis of the quasisteady Fokker-Planck equation, we estimate the effective diffusivity to scale as T

  14. Synthesis of sodium zeolites from natural and modified diatomite

    Microsoft Academic Search

    A. Chaisena; K. Rangsriwatananon

    2005-01-01

    This project is related with the synthesis of sodium zeolites using natural and modified diatomite as starting materials. The synthesis process consisted of conventional hydrothermal alkaline activation, using NaOH as reagent. The process was studied as a function of the starting material, temperature, time, solid\\/liquid ratio and activation reagent concentration. The resulting crystals were identified by X-ray diffraction, and characterized

  15. Sensitized near infrared emission from lanthanide-exchanged zeolites

    SciTech Connect

    Monguzzi, A.; Macchi, G.; Meinardi, F.; Tubino, R. [CNR-INFM and Department of Material Science, University of Milano-Bicocca, via Cozzi 53, I-20125 Milano (Italy); Burger, M. [Department of Physics A. Volta, University of Pavia, via Bassi 6, I-27100 Pavia (Italy); Calzaferri, G. [University of Berne, Department of Chemistry and Biochemistry, Freiestr. 3 CH-3012 Berne (Switzerland)

    2008-03-24

    In this work, we present an alternative approach to sensitize the near infrared emission of Er{sup 3+} ions (used in telecom applications) by exploiting the geometrical confinement occurring in porous zeolites structures. The sensitization of the Ln ion is obtained by energy transfer between a suitable organic molecule acting as an antenna and the emitting ion arranged in closed proximity, thus, avoiding the limits imposed by the coordination chemistry.

  16. A study of platinum-thulium\\/KL zeolite reforming catalysts

    Microsoft Academic Search

    Xiangming Fang; Fengyi Li; Laitao Luo

    1996-01-01

    The PtKL catalyst modified by Tm2O3 has been characterized by the n-hexane, methylcyclopentane (MCP) and cyclohexane conversion reaction. The results show that the activity for the aromatization on Pt-Tm\\/KL zeolite catalysts containing thulium ranging from 0.05 to 0.2 wt.-% is higher than that on the PtKL catalyst, and the stability of the modified catalysts is remarkably improved. The influence of

  17. Direct electron crystallographic determination of zeolite zonal structures

    Microsoft Academic Search

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

    2007-01-01

    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

  18. Origin of strong acidity in lanthanum-exchanged zeolites 

    E-print Network

    Carvajal Freese, Ralf R.

    1989-01-01

    compositions for the hydrocarbon process include Czo-C4o molecules comprised of single and fused aromatic rings, naphthene rings, and paraffins (3). These molecules are converted mainly by acid-catalyzed reactions, such as isomerization, polymerization...ORIGIN OF STRONG ACIDITY IN LANTHANUM- EXCHANGED ZEOLITES A Thesis by RALF R. CARVAJAL FREESE Submitted to the Office of Graduate Studies of Texas A&M University in the partial fulfillment of the requirements for the degree of MASTER...

  19. A Simple Model for Strontium Breakthrough on Zeolite Columns

    Microsoft Academic Search

    J. J. Perona; A. C. Coroneos; T. E. Kent; S. A. Richardson

    1995-01-01

    The Process Waste Treatment Plant (PWTP) at the Oak Ridge National Laboratory is designed to remove radioactive contaminants, principally Sr, from process wastewater. Planned upgrades to the PWTP will use chabazite zeolite columns. Pilot-scale studies have shown that mass transfer zone lengths increase from 10 to about 30 cm as the superficial velocity increases from 5.5 to 22 cm\\/min. Calculations

  20. UO2 Sorption in Natural Mexican Erionite and Y Zeolite

    Microsoft Academic Search

    M. T. Olguín; M. Solache; M. Asomoza; D. Acosta; P. Bosch; S. Bulbulian

    1994-01-01

    The use of Y zeolite and erionite to remove UO2 ions from aqueous solutions has been investigated. The effect of temperature, the concentration of UO2 uptake, the diffusion coefficients, and the ion-exchange isotherms were also studied. X-ray diffraction, thermal analyses, and transmission electron microsocopy were used to characterize the solids. The UO2 content was determined by neutron activation analysis. The

  1. Formulation of cracking catalyst based on zeolite and natural clays

    Microsoft Academic Search

    R. R. Aliev; M. I. Lupina

    1995-01-01

    Domestically manufactured cracking catalysts are based on a synthetic amorphous aluminosilicate matrix and Y zeolite. A multistage {open_quotes}gel{close_quotes} technology is used in manufacturing the catalysts. The process includes mixing solutions of sodium silicate and acidic aluminum sulfate, forming, syneresis, and activation of the beaded gel. In the manufacture of bead catalysts, the next steps in the process are washing, drying,

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

    Microsoft Academic Search

    Sabina A. Rouf; Mladen Ei?

    1998-01-01

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

  3. Skeletal Isomerization of 1Butene on MCM-22 Zeolite Catalyst

    Microsoft Academic Search

    M. A. Asensi; A. Corma; A. Mart??nez

    1996-01-01

    The skeletal isomerization of 1-butene has been studied on two MCM-22 zeolite catalysts synthesized with different Si\\/Al ratios, i.e., 15 and 47, under a wide range of operating conditions. Product yields are a function ofn-butene conversion, and a maximum of isobutene yield is found at ca. 50% conversion. Besides isobutene, propylene and pentenes, which are formed by dimerization-cracking reactions, are

  4. Formaldehyde base catalysis by NaX zeolite

    Microsoft Academic Search

    S. Trigerman; E. Biron; A. H. Weiss

    1977-01-01

    Reactions of formaldehyde to produce formose sugars at 95°C in aqueous solutions were studied over a trickle bed of NaX Zeolite spheres. When effluent pH was in the range of 5 to 7, a rapid irreversible catalyst deactivation from an initial 50% conversion occurred. The catalyst was destroyed in less than five hours by formic acid produced by the undesired

  5. Kinetic Parameters of Polyethylene Degradation by the Natural Zeolite Chabazite

    Microsoft Academic Search

    V. J. Fernandes; A. S. Araujo; R. A. Medeiros; J. R. Matos; L. P. Mercuri; A. O. Silva; D. M. A. Melo

    1999-01-01

    High-density polyethylene (PE) was subjected to thermal degradation alone and in the presence of an ammonium-exchanged zeolite\\u000a chabazite (CHA\\/PE). The processes were carried out in a reactor connected online to a gas chromatograph\\/mass spectrometer\\u000a in order to analyse the evolved products. Polymer degradation was also evaluated by thermogravimetry, from room temperature\\u000a up to 800°C, under a dynamic nitrogen atmosphere, with

  6. Origin of strong acidity in lanthanum-exchanged zeolites

    E-print Network

    Carvajal Freese, Ralf R.

    1989-01-01

    reagents for zeolite dealumination (57, 58). Fluoride ions are excellent complexing agents, and aluminum can be extracted from the framework in the form ol' water soluble complexes. In addition, ammonium hexafluorosilicate forms monomeric silicon species.... DEALUMINATION WITH AMMONIUM HEXAFLUOROSILICATE 27 D. X-RAY DIFFRACTION. . E. SOLID STATE MAGIC ANGLE SPINNING NMR. . . . . I. Aluminum content evaluation. 2. Evaluation of acid sites. . F. FOURIER TRANSFORM IR, G. SAMPLE PREPARATION FOR ELEMENTAL ANALYSIS...

  7. Effect of organic complexation on copper accumulation and toxicity to the estuarine red macroalga Ceramium tenuicorne: a test of the free ion activity model.

    PubMed

    Ytreberg, Erik; Karlsson, Jenny; Hoppe, Sabina; Eklund, Britta; Ndungu, Kuria

    2011-04-01

    Current water quality criteria (WQC) regulations on copper toxicity to biota are still based on total dissolved (<0.4 ?m membrane filter) copper concentrations with a hardness modification for freshwaters. There are however ongoing efforts to incorporate metal speciation in WQC and toxicity regulations (such as the biotic ligand model-BLM) for copper and other metals. Here, we show that copper accumulation and growth inhibition of the Baltic macroalga Ceramium tenuicorne exposed to copper in artificial seawater at typical coastal and estuarine DOC concentrations (similar to 2-4 mg/L-C as fulvic acid) are better correlated to weakly complexed and total dissolved copper concentrations rather than the free copper concentration [Cu2+]. Our results using a combination of competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) measurements and model calculations (using visual MINTEQ incorporating the Stockholm Humic Model) show that copper accumulation in C. tenuicorne only correlates linearly well to [Cu2+] at relatively high [Cu2+] and in the absence of fulvic acid. Thus the FIAM fails to describe copper accumulation in C. tenuicorne at copper and DOC concentrations typical of most marine waters. These results seem to indicate that at ambient total dissolved copper concentration in coastal and estuarine waters, C. tenuicorne might be able to access a sizable fraction of organically complexed copper when free copper concentration to the cell membrane is diffusion limited. PMID:21391651

  8. Novel Zeolitic Imidazolate Framework/Polymer Membranes for Hydrogen Separations in Coal Processing

    SciTech Connect

    Musselman, Inga H.

    2013-01-31

    Nanoparticles of zeolitic imidazolate frameworks and other related hybrid materials were prepared by modifying published synthesis procedures by introducing bases, changing stoichiometric ratios, or adjusting reaction conditions. These materials were stable at temperatures >300 °C and were compatible with the polymer matrices used to prepare mixed-matrix membranes (MMMs). MMMs tested at 300 °C exhibited a >30 fold increase in permeability, compared to those measured at 35 °C, while maintaining H{sub 2}/CO{sub 2} selectivity. Measurements at high pressure (up to 30 atm) and high temperature (up to 300 °C) resulted in an increase in gas flux across the membrane with retention of selectivity. No variations in permeability were observed at high pressures at either 35 or 300 °C. CO{sub 2}-induced plasticization was not observed for Matrimid®, VTEC, and PBI polymers or their MMMs at 30 atm and 300 °C. Membrane surface modification by cross-linking with ethylenediamine resulted in an increase in H{sub 2}/CO{sub 2} selectivity at 35 °C. Spectrometric analysis showed that the cross-linking was effective to temperatures <150 °C. At higher temperatures, the cross-linked membranes exhibit a H2/CO2 selectivity similar to the uncrosslinked polymer.

  9. Hohenheim Consensus Workshop: Copper

    Microsoft Academic Search

    K Schümann; HG Classen; HH Dieter; J König; G Multhaup; M Rükgauer; KH Summer; J Bernhardt; HK Biesalski

    2002-01-01

    Copper (Cu) is an essential trace element with many physiological functions. Homeostatic mechanisms exist to allow Cu to act as a cofactor in enzymatic processes and to prevent accumulation of Cu to toxic levels. The aim of this commentary is to better understand the role of dietary Cu supply in deficiency and under physiological and pathological conditions. The essentiality of

  10. Earth's anthrobiogeochemical copper cycle

    Microsoft Academic Search

    J. N. Rauch; T. E. Graedel

    2007-01-01

    An “anthrobiogeochemical” copper cycle, from Earth's core to the Moon, combining natural biogeochemical and human anthropogenic stocks and flows is derived for the mid-1990s. Although some aspects of the quantification have moderate to high uncertainty, the anthropogenic mining, manufacturing, and use flows (on the order of 104 Gg Cu\\/yr) clearly dominate the cycle. In contrast, the natural repositories of Earth's

  11. Creative Copper Crests

    ERIC Educational Resources Information Center

    Knab, Thomas

    2011-01-01

    In this article, the author discusses how to create an art activity that would link the computer-created business cards of fourth-grade students with an upcoming school-wide medieval event. Creating family crests from copper foil would be a great connection, since they, like business cards, are an individual's way to identify themselves to others.…

  12. Superhydrophobic Copper Surfaces

    NSDL National Science Digital Library

    This lesson from The Lawrence Hall of Science was taught in fall 2012 and focuses on superhydrophobic and superhydrophilic surfaces. Students will experiment with these materials by chemically modifying copper. This page includes links to the Source Article for the Hands-on Module as well as four documents for instructor use in teaching the lab.

  13. Development of a dissolved oxygen sensor using tris(bipyridyl) ruthenium (II) complexes entrapped in highly siliceous zeolites

    Microsoft Academic Search

    Pramatha Payra; Prabir K. Dutta

    2003-01-01

    Defect-free highly siliceous zeolites were prepared by dealumination of zeolite Y using silicon tetrachloride. Tris(bipyridyl) ruthenium (II) complex, [Ru(bpy)3]2+, was synthesized inside the supercages of the highly siliceous faujasitic zeolites using neutral Ru(bpy)Cl3 as the starting material. The conventional procedure using ion-exchange of hexammine ruthenium could not be used because of the lack of ion-exchange sites in the siliceous zeolites.

  14. Effects of capillary condensation on adsorption and thermal desorption dynamics of water in zeolite 13X and layered beds

    Microsoft Academic Search

    Hyungwoong Ahn; Chang-Ha Lee

    2004-01-01

    The effects of capillary condensation on the adsorption and thermal desorption dynamics of water in zeolite 13X beds and layered beds with zeolite 13X\\/silica gel or zeolite 13X\\/alumina were experimentally and theoretically studied. As the equilibrium isotherm of water on zeolite 13X pellet was found to be most favorable at a low relative humidity and indicated capillary condensation at a

  15. Synthetic zeolites and other microporous oxide molecular sieves.

    PubMed

    Sherman, J D

    1999-03-30

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol. PMID:10097059

  16. Synthesis of colloidal suspensions of zeolite ZSM-2

    SciTech Connect

    Schoeman, B.J.; Sterte, J.; Otterstedt, J.E. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Chemistry] [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Chemistry

    1995-03-15

    Discrete colloidal particles of zeolite ZSM-2 with crystal sizes less than 100 nm, in the form of aqueous suspensions, have been synthesized in tetramethylammonium (TMA)-aluminosilicate solutions in the presence of either lithium or a combination of lithium and sodium hydroxide. The well-crystallized ZSM-2 has a specific surface area of 781 m{sup 2}/g after purification and removal of the organic base by calcination. Synthesis times (t) are as short as 3 < t < 12 h and in certain cases, less than 3 h, less than those previously reported in the literature. Prolonged hydrothermal treatment of sols in the presence of sodium cations (>12 h) results in the phase transformation of ZSM-2 to the nitrogeneous edingtonite zeolite (Li,Na)-E. The synthesis of nitrogeneous (Li,Na)-E is also favored by a high TMA content in conjunction with sodium, whereas synthesis of zeolite N-A is favored by a high sodium content. Furthermore, it is shown that colloidal suspensions of TMA sodalite with crystal sizes less than 40 nm are synthesized in the absence of alkali cations.

  17. The safety of synthetic zeolites used in detergents.

    PubMed

    Fruijtier-Pölloth, Claudia

    2009-01-01

    Synthetic zeolites are replacing phosphates as builders in laundry detergents; workers and consumers may, therefore, increasingly be exposed to these materials and it is important to assess their safety. This article puts mechanistic, toxicological and exposure data into context for a safety assessment. Zeolites are hygroscopic compounds with ion-exchanging properties. They may partially decompose under acidic conditions such as in the stomach releasing sodium ions, silicic acid and aluminum salts. The intact molecule is not bioavailable after oral intake or exposure through the dermal and inhalational routes. Under current conditions of manufacture and use, no systemic toxicity is to be expected from neither the intact molecule nor the degradation products; a significant effect on the bioavailability of other compounds is not likely. Zeolites may cause local irritation. It is, therefore, important to minimise occupational exposure. The co-operation of detergent manufacturers with the manufacturers of washing machines is necessary to find the right balance between environmental aspects such as energy and water savings and the occurrence of detergent residues on textiles due to insufficient rinsing. PMID:18563391

  18. Mononuclear iridium dinitrogen complexes bonded to zeolite HY.

    PubMed

    Yang, Dong; Chen, Mingyang; Martinez-Macias, Claudia; Dixon, David A; Gates, Bruce C

    2015-01-01

    The adsorption of N2 on structurally well-defined dealuminated HY zeolite-supported iridium diethylene complexes was investigated. Iridium dinitrogen complexes formed when the sample was exposed to N2 in H2 at 298?K, as shown by infrared spectra recorded with isotopically labeled N2 . Four supported species formed in various flowing gases: Ir(N2 ), Ir(N2 )(N2 ), Ir(C2 H5 )(N2 ), and Ir(H)(N2 ). Their interconversions are summarized in a reaction network, showing, for example, that, in the presence of N2 , Ir(N2 ) was the predominant dinitrogen species at temperatures of 273-373?K. Ir(CO)(N2 ) formed transiently in flowing CO, and in the presence of H2 , rather stable iridium hydride complexes formed. Four structural models of each iridium complex bonded at the acidic sites of the zeolite were employed in a computational investigation, showing that the calculated vibrational frequencies agree well with experiment when full calculations are done at the level of density functional theory, independent of the size of the model of the zeolite. PMID:25381885

  19. CO2 adsorption in amine-grafted zeolite 13X

    NASA Astrophysics Data System (ADS)

    Bezerra, Diôgo P.; Silva, Francisco W. M. da; Moura, Pedro A. S. de; Sousa, Allyson G. S.; Vieira, Rodrigo S.; Rodriguez-Castellon, Enrique; Azevedo, Diana C. S.

    2014-09-01

    The adsorption of CO2 on Zeolite 13X functionalized with amino groups was studied. Adsorbent functionalization was carried out by grafting with different loads of monoethanolamine (MEA). The adsorbents were characterized by N2 adsorption/desorption isotherms at 77 K, x-ray diffraction, TGA, in situ FTIR, XPS and adsorption microcalorimetry. CO2 isotherms were studied in a gravimetric device up to 10 bar at 298 and 348 K. It was found that increasing loads of amine to the adsorbent tend to reduce micropore volume of the resulting adsorbents by pore blocking with MEA. There is experimental evidence that part of the loaded MEA is effectively covalently bonded to the zeolitic structure, whereas there is also physisorbed excess MEA which will eventually be desorbed by raising the temperature beyond MEA boiling point. Heats of adsorption at nearly zero coverage indicate that some of the adsorbed CO2 reacts with available amino groups, which agrees with the finding that the adsorption capacity increases with increasing temperature for the modified zeolite with the highest MEA load.

  20. Theoretical analysis of the thermodynamics of ZSM-11 zeolite synthesis

    SciTech Connect

    Shen, V.; Watanabe, K.; Bell, A.T. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States); [Univ. of California, Berkeley, CA (United States)

    1997-03-20

    Theoretical methods are used to analyze the thermodynamics of ZSM-11 synthesis from amorphous silica and an aqueous solution of tetraalkylammonium hydroxide (TAAOH). The overall process is represented by the reaction 96SiO{sub 2}(a){sup +} n(TAA{sup +}/OH{sup -}/200H{sub 2}O){sup =} (nTAA{sup +}/Z{sup n-}){sup +} 200nH{sub 2}O. Both tetrapropylammonium (TPA{sup +}) and tetrabutylammonium (TBA{sup +}) cations are considered as the structure-directing agents, and calculations are performed for occlusion of either three or four TAA{sup +} cations per unit cell of the zeolite. Both estimates of the change in internal energy and Gibbs free energy reveal that the synthesis of ZSM-11 should be favored by the occlusion of three TBA{sup +} cations per unit cell, consistent with experimental observation. The present analysis also demonstrates the importance of energy and entropy changes associated with the dehydration of TAA{sup +} and OH{sup -} ion and with the occlusion of TAA{sup +} cations into the zeolite. The interactions of OH{sup -} anions with the zeolite framework to form defects in the form of siloxy (=V@SiO{sup -}) groups are also considered. 46 refs., 5 tabs.

  1. Competitive adsorption of dyes and heavy metals on zeolitic structures.

    PubMed

    Hernández-Montoya, V; Pérez-Cruz, M A; Mendoza-Castillo, D I; Moreno-Virgen, M R; Bonilla-Petriciolet, A

    2013-02-15

    The adsorption of Acid blue 25, basic blue 9, basic violet 3, Pb(2+), Ni(2+), Zn(2+) and Cd(2+) ions has been studied in single and dye-metal binary solutions using two mineral materials: Clinoptilolite (CL) and ER (Erionite). These zeolites were characterized by FT-IR spectroscopy; potentiometric titration and nitrogen adsorption isotherms at 77 K to obtain their textural parameters. Results indicated that ER has an acidic character and a high specific surface (401 m(2) g(-1)) in contrast with the zeolite CL (21 m(2) g(-1)). Surprisingly, the removal of dyes was very similar for the two zeolites and they showed a considerable selectivity by the basic dyes in comparison with the acid dyes. In the case of heavy metals, ER was more effective in the adsorption process showing a selectivity of: Pb(2+) > Ni(2+) > Zn(2+) > Cd(2+). In the multicomponent adsorption experiments an antagonistic effect was observed in the removal of basic dyes and heavy metals. Particularly, the adsorbed amount of basic violet 3 decreased more significantly when the heavy metals are presents in contrast with the basic blue 9. PMID:23321372

  2. Catalytic decomposition of nitrous oxide on metal exchange zeolites

    SciTech Connect

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

    1993-12-31

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

  3. Mesopore quality determines the lifetime of hierarchically structured zeolite catalysts

    NASA Astrophysics Data System (ADS)

    Milina, Maria; Mitchell, Sharon; Crivelli, Paolo; Cooke, David; Pérez-Ramírez, Javier

    2014-05-01

    Deactivation due to coking limits the lifetime of zeolite catalysts in the production of chemicals and fuels. Superior performance can be achieved through hierarchically structuring the zeolite porosity, yet no relation has been established between the mesopore architecture and the catalyst lifetime. Here we introduce a top-down demetallation strategy to locate mesopores in different regions of MFI-type crystals with identical bulk porous and acidic properties. In contrast, well-established bottom-up strategies as carbon templating and seed silanization fail to yield materials with matching characteristics. Advanced characterization tools capable of accurately discriminating the mesopore size, distribution and connectivity are applied to corroborate the concept of mesopore quality. Positron annihilation lifetime spectroscopy proves powerful to quantify the global connectivity of the intracrystalline pore network, which, as demonstrated in the conversions of methanol or of propanal to hydrocarbons, is closely linked to the lifetime of zeolite catalysts. The findings emphasize the need to aptly tailor hierarchical materials for maximal catalytic advantage.

  4. Enzymatic modification of schizophyllan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An enzymatic method was developed for the progressive modification of the polysaccharide schizophyllan. Fungal strains Hypocrea nigricans NRRL 62555, Penicillium crustosum NRRL 62558, and Penicillium simplicissimum NRRL 62550 were previously identified as novel sources of ß-endoglucanase with specif...

  5. Reducing adverse effects from UV sunscreens by zeolite encapsulation: comparison of oxybenzone in solution and in zeolites.

    PubMed

    Chrétien, Michelle N; Heafey, Eve; Scaiano, Juan C

    2010-01-01

    Oxybenzone (OXB) is one of the most widely employed sunscreen ingredients, yet its allowed load is limited to a maximum of 6% reflecting the frequency with which adverse effects are reported. From a spectroscopic point of view, OXB has excellent absorption properties in both the UVB and UVA regions. We propose that zeolite encapsulation can lead to a sunscreen composite ingredient, that we describe as a supramolecular sunscreen, that will retain the excellent spectroscopic properties of OXB, while preventing contact between the skin and the active ingredient. OXB is very photostable, with the only photodegradative pathway observed being the monophotonic photoejection of electrons that leads to trace yields of phenoxyl radicals; this trace reaction is so minor that it cannot be detected from the recovery of unreacted OXB following UV exposure. Solution, as well as powder and in vitro studies of the supramolecular sunscreen, demonstrate that the protective properties of OXB are totally preserved when encapsulated in zeolite NaY. PMID:19930122

  6. Catalytic activity of pentasil type zeolites with different structures of the channels, in n-Hexane conversion

    Microsoft Academic Search

    E. N. Rosolovskaya; O. V. Barsukov; N. F. Meged; V. I. Trunova

    1985-01-01

    Hydrothermal synthesis using tetrabutylammonium (TBA) and monoethanolamine (MEA) has been applied to the synthesis of high-silica zeolites of the pentasil type, both with the same content of aluminum in the elementary cell and with identical dimensions of the crystals. The zeolites had the same catalytic activity in the overall conversion of hexane, but differed in selectivity. The zeolite obtained with

  7. Oxidative dehydrogenation (ODH) of ethane with O2 as oxidant on selected transition metal-loaded zeolites

    E-print Network

    Poeppelmeier, Kenneth R.

    suggest that the catalyst support can affect ODHE performance. Zeolites, which have molecular scale pore-loaded zeolites Xufeng Lin, Cathleen A. Hoel, Wolfgang M.H. Sachtler, Kenneth R. Poeppelmeier *, Eric Weitz productivity and selectivity Transition metal Y Zeolite a b s t r a c t Ni-, Cu-, and Fe-loaded acidic

  8. Enhanced ammonia nitrogen removal using consistent ammonium exchange of modified zeolite and biological regeneration in a sequencing batch reactor process

    Microsoft Academic Search

    Yun Xia Wei; Zheng Fang Ye; Yao Long Wang; Ming Guang Ma; Yan Feng Li

    2011-01-01

    Utilizing preferential ion exchange of the modified zeolite, the zeo?sequencing batch reactor (SBR) is recommended for a new nitrogen removal process. In this study, natural zeolite was modified by sodium chloride to enhance sorption capacity for ammoniacal nitrogen. The untreated and treated zeolite was characterized by XPS and XRD techniques. The sorption isotherm tests showed that equilibrium sorption data were

  9. Control of acid-site location of ZSM-5 zeolite membrane and its application to the MTO reaction

    Microsoft Academic Search

    Teruoki Tago; Kazuyuki Iwakai; Ken Morita; Katsunori Tanaka; Takao Masuda

    2005-01-01

    ZSM-5 zeolite membrane, which shows high selectivity toward olefins in the methanol conversion, was developed by controlling the location of the acid sites. First, the ZSM-5 zeolite catalyst membrane without pinholes was successfully prepared by synthesizing a ZSM-5 zeolite layer on an outer surface of a cylindrical alumina ceramic filter. The membrane was used as the catalytic membrane reactor to

  10. Male genital modification

    Microsoft Academic Search

    Raven Rowanchilde

    1996-01-01

    By modifying the body in meaningful ways, human beings establish their identity and social status. Lip plugs, ear plugs, penis\\u000a sheaths, cosmetics, ornaments, scarification, body piercings, and genital modifications encode and transmit messages about\\u000a age, sex, social status, health, and attractiveness from one individual to another. Through sociocultural sexual selection,\\u000a male genital modification plays an important role as a sociosexual

  11. Tyrosine Modifications in Aging

    PubMed Central

    Feeney, Maria B.

    2012-01-01

    Abstract Significance: The understanding of physiological and pathological processes involving protein oxidation, particularly under conditions of aging and oxidative stress, can be aided by proteomic identification of proteins that accumulate oxidative post-translational modifications only if these detected modifications are connected to functional consequences. The modification of tyrosine (Tyr) residues can elicit significant changes in protein structure and function, which, in some cases, may contribute to biological aging and age-related pathologies, such as atherosclerosis, neurodegeneration, and cataracts. Recent Advances: Studies characterizing proteins in which Tyr has been modified to 3-nitrotyrosine, 3,4-dihydroxyphenylalanine, 3,3?-dityrosine and other cross-links, or 3-chlorotyrosine are reviewed, with an emphasis on structural and functional consequences. Critical Issues: Distinguishing between inconsequential modifications and functionally significant ones requires careful biochemical and biophysical analysis of target proteins, as well as innovative methods for isolating the effects of the multiple modifications that often occur under oxidizing conditions. Future Directions: The labor-intensive task of isolating and characterizing individual modified proteins must continue, especially given the expanding list of known modifications. Emerging approaches, such as genetic and metabolic incorporation of unnatural amino acids, hold promise for additional focused studies of this kind. Antioxid. Redox Signal. 17, 1571–1579. PMID:22424390

  12. Shape-selective n-alkane hydroconversion at exterior zeolite surfaces

    Microsoft Academic Search

    Theo L. M. Maesen; Rajamani Krishna; Jasper M. van Baten; Berend Smit; Sofia Calero; Juan Manuel Castillo Sanchez

    2008-01-01

    A critical review of the adsorption and catalysis of n- and methylalkanes demonstrates that the interior surface of TON- and MTT-type zeolites dominates both adsorption and catalysis, and that the contribution from the exterior surface is negligible. For both n- and methylalkane isomers, the experimental Henry constants at the interior TON-type zeolite surface are more than an order of magnitude

  13. Adsorption of gases at low pressures on X-type zeolites

    Microsoft Academic Search

    V. Bosá?ek; J. Krása; P. Schürer

    1970-01-01

    This article is treating the experimental investigation of the sorption of gases on synthetic X-type zeolites, modified by the exchange of cations in the crystal lattice. The dynamic method has been applied. It has been found that the kinetics of sorption and the limiting pressure are influenced with the ion exchange. Zeolite CaX was found to be the most effective

  14. Metal-Exchanged Clay and Zeolite Additives as Smoke Suppressants and Fire Retardants for

    E-print Network

    Pike, Robert D.

    Metal-Exchanged Clay and Zeolite Additives as Smoke Suppressants and Fire Retardants for Poly studies showed that various metal- exchanged clays and zeolites containing only 3­4% of Cu(II), Cu(I), Zn blends of the clays, and the effectiveness of the additives was usually improved considerably by heat

  15. Zeolite Salt Occlusion: A Potential Route for the Immobilisation of Iodine-129? Neil C. Hyatt,1*

    E-print Network

    Sheffield, University of

    Zeolite ­ Salt Occlusion: A Potential Route for the Immobilisation of Iodine-129? Neil C. Hyatt,1 examined as possible starting routes to the long term immobilisation of iodine-129. Heating the salts, where the iodide salt migrates into the zeolite pores. Detailed studies of the Na-A / 5AgI complex

  16. Controlling size and yield of zeolite Y nanocrystals using tetramethylammonium bromide

    Microsoft Academic Search

    Brett A. Holmberg; Huanting Wang; Joseph M. Norbeck; Yushan Yan

    2003-01-01

    In this study, we developed an alternative synthesis technique for the production of small colloidal zeolite Y nanocrystals. By adding tetramethylammonium bromide as a second source of organic template, we were able to decouple and investigate the effect of two important synthesis parameters, tetramethylammonium concentration and anion concentration. Optimizing these two parameters allowed us to hydrothermally synthesize highly crystalline zeolite

  17. Magnetic zeolites: a new adsorbent for removal of metallic contaminants from water

    Microsoft Academic Search

    Luiz C. A. Oliveira; Diego I. Petkowicz; Alessandra Smaniotto; Sibele B. C. Pergher

    2004-01-01

    In this work the adsorption features of NaY zeolite with the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. These magnetic composites can be used as an adsorbent for metallic contaminants in water and subsequently removed from the medium by a simple magnetic process. The zeolites:iron oxide magnetic composites, were prepared by

  18. Fenton type processes for minimization of organic content in coloured wastewaters. Part II: Combination with zeolites

    Microsoft Academic Search

    Hrvoje Kuši?; Ana Lon?ari? Boži?; Natalija Koprivanac; Sanja Papi?

    2007-01-01

    The addition of solid particles, namely synthetic zeolites NH4ZSM5 and HY, was investigated in order to enhance the efficiency of AOPs for dye wastewater treatment. Experiments were conducted at the optimal operating parameters for each Fenton type process and studied coloured pollutants established in Part I of this study in order to find the optimal dose of applied zeolites and

  19. Dual templating function of Equisetum arvense in the preparation of zeolite macrostructures

    Microsoft Academic Search

    V. Valtchev; M. Smaihi; A. C. Faust; L. Vidal

    2004-01-01

    Biomimetic microporous structures were prepared by in situ laboratory zeolitization of a silica-rich plant, member of the Equisetophyta family. Leaves and stems of the dry plant were subjected to hydrothermal treatment into a clear ZSM-5 precursor solution. Highly reactive biomorphic silica deposited at the epidermal surface of the plant successfully promoted zeolite growth and provided composites containing up to 70

  20. The recyclable synthesis of hierarchical zeolite SAPO-34 with excellent MTO catalytic performance.

    PubMed

    Xi, Dongyang; Sun, Qiming; Chen, Xiaoxin; Wang, Ning; Yu, Jihong

    2015-07-14

    A facile and green route has been developed for the synthesis of hierarchical zeolite catalysts by recycling of waste mother-liquors. After three recycles of mother-liquors, the obtained hierarchical SAPO-34 zeolites retain high crystallinity, texture properties, and acidity, as well as excellent MTO catalytic performance as compared to the initially prepared catalysts. PMID:26121259

  1. Removal of Boron from Aqueous Solutions by Adsorption Using Fly Ash, Zeolite, and Demineralized Lignite

    Microsoft Academic Search

    Seren Yüksel; Yuda Yürüm

    2009-01-01

    In the present study for the purpose of removal of boron from water by adsorption using adsorbents like fly ash, natural zeolite, and demineralized lignite was investigated. Boron in water was removed with fly ash, zeolite, and demineralized lignite with different capacities. Ninety-four percent boron was removed using fly ash. Batch experiments were conducted to test the removal capacity, to

  2. Catalysis Today 87 (2003) 195203 Preparation and characterization of zeolite catalysts

    E-print Network

    Kim, Ji Man

    2003-01-01

    Catalysis Today 87 (2003) 195­203 Preparation and characterization of zeolite catalysts. H-Beta zeolite shows higher conversion and catalytic stability than other catalysts, a Catalyst and Surface Laboratory, Department of Applied Chemistry, Ajou University, Suwon 442-749, South

  3. Methane activation without using oxidants over Mo\\/HZSM-5 zeolite catalysts

    Microsoft Academic Search

    Yide Xu; Shetian Liu; Xiexian Guo; Lingsheng Wang; Maosong Xie

    1994-01-01

    The effect of Mo loading, calcination temperature, reaction temperature and space velocity on the catalytic performance of methane dehydrogenation and aromatization without using oxidants over Mo\\/HZSM-5 has been studied. The XRD and BET measurements show that Mo species are highly dispersed in the channels of the HZSM-5 zeolite, resulting from the interaction between the Mo species and the zeolite, which

  4. The Use of Zeolite and Oxidant Generating Devices in Air Cleaning

    Microsoft Academic Search

    Teresa S. C. Law; Christopher Y. H. Chao; George Y. W. Chan; Anthony K. Y. Law

    2004-01-01

    This paper presents the effects of combining a zeolite filter with an oxidant-generating device to remove Volatile Organic Compounds (VOCs) from air. Two types of synthetic zeolites were tested. The sources of VOCs used in the tests were acetone and dried shark fins. Dried shark fins are commonly used in Chinese cooking and they emit amine related compounds with a

  5. Composite 5A zeolite with ultrathin porous TiO2 coating for selective gas adsorption.

    PubMed

    Song, Zhuonan; Huang, Yi; Wang, Lei; Li, Shiguang; Yu, Miao

    2015-01-01

    A composite zeolite adsorbent was prepared by conformally depositing an ultrathin porous TiO2 coating on the external surface of the 5A zeolite by molecular layer deposition (MLD) and subsequent calcination. The composite adsorbent showed significantly improved ideal adsorption selectivity for CO2-CH4, CO2-N2 and propylene-propane. PMID:25406720

  6. Experiments for the Undergraduate Laboratory that Illustrate the Size-Exclusion Properties of Zeolite Molecular Sieves

    ERIC Educational Resources Information Center

    Cooke, Jason; Henderson, Eric J.

    2009-01-01

    Experiments are presented that demonstrate the size-exclusion properties of zeolites and reveal the reason for naming zeolites "molecular sieves". If an IR spectrometer is available, the adsorption or exclusion of alcohols of varying sizes from dichloromethane or chloroform solutions can be readily demonstrated by monitoring changes in the…

  7. Can one and two-dimensional solid-state NMR fingerprint zeolite framework topology?

    PubMed

    Martineau, Charlotte; Vial, Sandrine; Barth, Dominique; Quessette, Franck; Taulelle, Francis

    2015-02-01

    In this contribution, we have explored the potential and strength of one-dimensional (1D) (29)Si and two-dimensional (2D) (29)S-(29)Si and (29)Si-(17)O NMR as invariants of non-oriented graph for fingerprinting zeolite frameworks. 1D and 2D (29)Si NMR can indeed provide indications on the graph vertices, edges and allow the construction of the adjacency matrix, i.e. the set of connections between the graph vertices. From the structural data, hypothetical 1D (29)Si and 2D (29)Si-(29)Si NMR signatures for 193 of the zeolite frameworks reported in the Atlas of Zeolite Structures have been generated. Comparison between all signatures shows that thanks to the 1D (29)Si NMR data only, almost 20% of the known zeolite frameworks could be distinguished. Further NMR signatures were generated by taking into account 2D (29)Si-(29)Si and (29)Si-(17)O correlations. By sorting and comparison of all the NMR data, up to 80% of the listed zeolites could be unambiguously discriminated. This work indicates that (i) solid-state NMR data indeed represent a rather strong graph invariant for zeolite framework, (ii) despite their difficulties and costs (isotopic labeling is often required, the NMR measurements can be long), (29)Si and (17)O NMR measurements are worth being investigated in the frame of zeolites structure resolution. This approach could also be generalized to other zeolite-related materials containing NMR-measurable nuclides. PMID:25454465

  8. Colossal cages in zeolitic imidazolate frameworks as selective carbon dioxide reservoirs

    Microsoft Academic Search

    Bo Wang; Adrien P. Côté; Hiroyasu Furukawa; Michael O'Keeffe; Omar M. Yaghi

    2008-01-01

    Zeolitic imidazolate frameworks (ZIFs) are porous crystalline materials with tetrahedral networks that resemble those of zeolites: transition metals (Zn, Co) replace tetrahedrally coordinated atoms (for example, Si), and imidazolate links replace oxygen bridges. A striking feature of these materials is that the structure adopted by a given ZIF is determined by link-link interactions, rather than by the structure directing agents

  9. Hollow mesoporous zeolite microspheres: hierarchical macro-/meso-/microporous structure and exceptionally enhanced adsorption properties.

    PubMed

    Zhou, Jian; Hua, Zile; Wu, Wei; Liu, Zhicheng; Zhu, Yan; Chen, Yu; Shi, Jianlin

    2011-12-21

    We report the synthesis of a new kind of uniform hollow zeolite microspheres with hierarchical macro-/meso-/microporosity by an efficient strategy combining bi-templating, steam-assisted crystallization and then a mild alkaline etching method. This novel product has a hollow architecture, highly crystallized zeolite shells and more importantly, high dye adsorption capabilities. PMID:22041854

  10. 21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125...CERTIFICATION Drugs § 73.1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper...

  11. 21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125...CERTIFICATION Drugs § 73.1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper...

  12. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125... Cosmetics § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper...

  13. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125... Cosmetics § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper...

  14. 21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125...CERTIFICATION Drugs § 73.1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper...

  15. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125... Cosmetics § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper...

  16. 21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125...CERTIFICATION Drugs § 73.1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper...

  17. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125... Cosmetics § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper...

  18. 21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125...CERTIFICATION Drugs § 73.1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper...

  19. 21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125... Cosmetics § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper...

  20. Fate of copper in ponds.

    PubMed

    McIntosh, A W

    1975-03-01

    Treatments of 3 ppm copper sulfate (CuSO4-5H2O) were applied to two small aquatic systems in Michigan in 1971. To study the pathways of the added copper, samples of water, sediment, aquatic macrophytes, filamentous algae, and fish were collected and analyzed by atomic absorption. Sampling was initiated before treatment and continued up to 4 months in one of the ponds. Dissolved copper concentrations in water decreased rapidly immediately after treatment and then gradually to background levels. Reduction of dissolved copper may have involved initial precipitation of an insoluble compound, such as malachite, followed by sediment adsorption of soluble copper complexes and copper released from aquatic plants. Levels of copper in sediment increased rapidly at first and gradually later in the study. Aquatic plants and filamentous algae accumulated very high levels of copper. Uptake rates were apparently affected by water temperature and growth stages of the plants. Data indicate that aquatic macrophytes developing in one pond 10 weeks after treatment took up copper from the sediment. Although green sunfish (Lepomis cyanellus) accumulated copper soon after treatment, levels returned to background later in the study. PMID:1161446

  1. Discovery of optimal zeolites for challenging separations and chemical transformations using predictive materials modeling

    NASA Astrophysics Data System (ADS)

    Bai, Peng; Jeon, Mi Young; Ren, Limin; Knight, Chris; Deem, Michael W.; Tsapatsis, Michael; Siepmann, J. Ilja

    2015-01-01

    Zeolites play numerous important roles in modern petroleum refineries and have the potential to advance the production of fuels and chemical feedstocks from renewable resources. The performance of a zeolite as separation medium and catalyst depends on its framework structure. To date, 213 framework types have been synthesized and >330,000 thermodynamically accessible zeolite structures have been predicted. Hence, identification of optimal zeolites for a given application from the large pool of candidate structures is attractive for accelerating the pace of materials discovery. Here we identify, through a large-scale, multi-step computational screening process, promising zeolite structures for two energy-related applications: the purification of ethanol from fermentation broths and the hydroisomerization of alkanes with 18–30 carbon atoms encountered in petroleum refining. These results demonstrate that predictive modelling and data-driven science can now be applied to solve some of the most challenging separation problems involving highly non-ideal mixtures and highly articulated compounds.

  2. Synthesis of hybrid zeolite materials with TiO2 nanocrystals using solid-solid method

    NASA Astrophysics Data System (ADS)

    Orha, Corina; Lazau, Carmen; Ratiu, Cornelia; Sfirloaga, Paula; Vlazan, Paulina; Ioitescu, Alexandra; Manea, Florica; Barvinschi, Paul; Muscutariu, Ioan; Grozescu, Ioan

    2009-03-01

    Zeolite seems to be a promising support for TiO2 photocatalyst because of its regular pores and good adsorption ability. TiO2 supported on zeolite integrates the photocatalytic activity of TiO2 with the adsorption properties of zeolites. The aim of this paper was the syntheses and characterizations of functionalized zeolite materials with undoped, Fe-doped and N-doped TiO2 nanocrystals. The zeolite hybrid materials impregnation with titanium dioxide was achieved through solid-solid method. TiO2 doped with metallic (Fe) and non-metallic (N) ions was obtained directly from precursors by sol-gel and hydrothermal methods. The hybrid materials were characterized by XRD, SEM with EDAX, IR and AFM.

  3. Bionanocomposites of regenerated cellulose/zeolite prepared using environmentally benign ionic liquid solvent.

    PubMed

    Soheilmoghaddam, Mohammad; Wahit, Mat Uzir; Tuck Whye, Wong; Ibrahim Akos, Noel; Heidar Pour, Raheleh; Ali Yussuf, Abdirahman

    2014-06-15

    Bionanocomposite films based on regenerated cellulose (RC) and incorporated with zeolite at different concentrations were fabricated by dissolving cellulose in 1-ethyl-3-methylimidazolium chloride (EMIMCl) ionic liquid using a simple green method. The interactions between the zeolite and the cellulose matrix were confirmed by Fourier transform infrared spectra. Mechanical properties of the nanocomposite films significantly improved as compared with the pure regenerated cellulose film, without the loss of extensibility. Zeolite incorporation enhanced the thermal stability and char yield of the nanocomposites. The scanning electron microscopy and transmission electron microscopy showed that zeolite was uniformly dispersed in the regenerated cellulose matrix. In vitro cytotoxicity test demonstrated that both RC and RC/zeolite nanocomposite films are cytocompatible. These results indicate that the prepared nanocomposites have potential applications in biodegradable packaging, membranes and biomedical areas. PMID:24721086

  4. In situ studies of zeolite syntheses using powder diffraction methods: Crystallization of ``instant zeolite A`` powder and CoAPO-5

    SciTech Connect

    Norby, P. [Odense Univ. (Denmark). Dept. of Chemistry; Christensen, A.N. [Aarhus Univ. (Denmark). Dept. of Chemistry; Hanson, J.C. [Brookhaven National Lab., Upton, NY (United States)

    1994-02-01

    A series of hydrothermal zeolite synthesis were performed on a powder diffractometer using synchrotron radiation and a position sensitive detector. Direct observation of the induction period (nucleation stage), crystallization and transformation of zeolite 4A (Na-LTA) was possible due to the intense X-ray beam which allows fast data collection. High pressure experiments were performed, allowing observation of hydrothermal synthesis of a cobalt substituted AlPO{sub 4}-zeolite, CoAPO-5, up to 165{degrees}C. The temperature dependence of crystallization rates of CoAPO-5 was studied. This is to our knowledge the first time resolved powder diffraction studies of zeolite syntheses using angle dispersive synchrotron powder diffraction.

  5. Study of intradrystalline diffusion in zeolites communication 3. Kinetics of adsorption of trans-2-butene by NaA and NaMgA zeolites

    SciTech Connect

    Broddak, R.; Dubinin, M.M.; Falko, L.A.; Gorlov, V.A.; Kuhlmann, B.; Scholner, E.; Voloshchuk, A.M.

    1985-09-10

    This article studies the kinetics of adsorption of trans-2-butene by NaA zeolite with a varying crystal size, microcrystalline granulated NaA zeolite using granules of different sizes, and microcrystalline powdered Na/sub 8/Mg/sub 2/A zeolite. It is shown that the rate of adsorption is determined by the intracrystalline diffusion and that the effect of transfer in the transport pores and the final rate of dissipation of the heat of adsorption can be neglected. In adsorption of trans-2-butene by Na/sub 8/Mg/sub 2/A zeolite with a stepwise change in the pressure of the adsorbate, the kinetic curves are satisfactorily described by an internal diffusion equation for the kinetics of isothermal adsorption. The kinetics of adsorption were studied at 303 degrees K from the one-component vapor phase on a vacuum adsorption setup using quartz spring balance.

  6. Experimental Investigation of the Effect Of Zeolite Coating Thickness on the Performance of a Novel Zeolite-Water Adsorption Heat Pump Module

    E-print Network

    Dawoud, B.; Hofle, P.; Chmielewski, S.

    2010-01-01

    A novel zeolite-water absorption heat pump module comprising an adsorber, an evaporator and a condenser heat exchanger as well as a module non-return valve in a hermetically sealed vessel is introduced. The investigated adsorber heat exchanger...

  7. Evolutionary aspects of copper binding centers in copper proteins

    Microsoft Academic Search

    B. Abolmaali; H. Taylor; U. Weser

    A great number of active centers in proteins and enzymes contain transition metals. Each metal imposes specific catalytic\\u000a properties on the protein which could not be achieved when employing a different metal. The special role and characteristic\\u000a reactivity of icoordinated copper is illustrated by looking at the evolutionary aspects of copper proteins. The evolution\\u000a of copper-binding sites is closely linked

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

    PubMed

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

    2002-11-01

    Environmental and/or occupational exposure to minerals, metals, and fibers can cause lung diseases that may develop years after exposure to the agents. The presence of toxic fibers such as asbestos in the environment plus the continuing development of new mineral or vitreous fibers requires a better understanding of the specific physical and chemical features of fibers/particles responsible for bioactivity. Toward that goal, we have tested aluminosilicate zeolites to establish biological and chemical structure-function correlations. Zeolites have known crystal structure, are subject to experimental manipulation, and can be synthesized and controlled to produce particles of selected size and shape. Naturally occurring zeolites include forms whose biological activity is reported to range from highly pathogenic (erionite) to essentially benign (mordenite). Thus, we used naturally occurring erionite and mordenite as well as an extensively studied synthetic zeolite based on faujasite (zeolite Y). Bioactivity was evaluated using lung macrophages of rat origin (cell line NR8383). Our objective was to quantitatively determine the biological response upon interaction of the test particulates/fibers with lung macrophages and to evaluate the efficacy of surface iron on the zeolites to promote the Fenton reaction. The biological assessment included measurement of the reactive oxygen species by flow cytometry and chemiluminescence techniques upon phagocytosis of the minerals. The chemical assessment included measuring the hydroxyl radicals generated from hydrogen peroxide by iron bound to the zeolite particles and fibers (Fenton reaction). Chromatography as well as absorption spectroscopy were used to quantitate the hydroxyl radicals. We found that upon exposure to the same mass of a specific type of particulate, the oxidative burst increased with decreasing particle size, but remained relatively independent of zeolite composition. On the other hand, the Fenton reaction depended on the type of zeolite, suggesting that the surface structure of the zeolite plays an important role. PMID:12417479

  9. Use of 64copper measurements to diagnose canine copper toxicosis.

    PubMed

    Brewer, G J; Schall, W; Dick, R; Yuzbasiyan-Gurkan, V; Thomas, M; Padgett, G

    1992-01-01

    Inherited canine copper toxicosis is a serious problem in Bedlington terriers and West Highland White terriers, and may also be a problem in other less-studied breeds. Affected dogs become ill at midlife with progressive and ultimately fatal liver disease. Treatments for removal of copper and prevention of copper accumulation are available, but are most effective if begun before the dog becomes ill. Until recently diagnosis has not been available until the dog is 1 year of age, and then only by an invasive liver biopsy with determination of liver copper concentration. The authors studied the use of 64copper for early diagnosis of canine copper toxicosis. Two procedures were evaluated. The first involved measuring the concentration of 64copper in blood 24 hours after oral administration of the radioisotope. At this time, 64copper was associated primarily with ceruloplasmin secreted into the blood by the liver. This procedure is useful in the diagnosis of the human counterpart, Wilson's disease. However, the authors found it to be nondiscriminatory between affected and unaffected dogs. In contrast, the second procedure, which involved measuring 64copper excreted in stool during 48 hours after an intravenous dose of radioisotope, yielded results that differentiated most affected and unaffected dogs. PMID:1548626

  10. Recommended nomenclature for zeolite minerals: report of the subcommittee on zeolites of the International Mineralogical Association, Commission of New Minerals and Mineral Names

    USGS Publications Warehouse

    Coombs, D.S.; Alberti, A.; Armbruster, T.; Artioli, G.; Colella, C.; Galli, E.; Grice, Joel D.; Liebau, F.; Mandarino, J.A.; Minato, H.; Nickel, E.H.; Passaglia, E.; Peacor, D.R.; Quartieri, S.; Rinaldi, R.; Ross, M.; Sheppard, R.A.; Tillmanns, E.; Vezzalini, G.

    1998-01-01

    This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association Commission of New Minerals and Mineral Names. In a working definition of a zeolite mineral used for review, interrupted tetrahedral framework structures are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is allowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundance in atomic proportions. To name these, the appropriate chemical symbol is attached by a hyphen to the series name as a suffix except for the names harmotome, pollucite and wairakite in the phillipsite and analcime series. Differences in space-group symmetry and in order-disorder relationships in zeolites having the same topologically distinctive framework do not in general provide adequate grounds for recognition of separate species. Zeolite species are not to be distinguished solely on Si:Al ratio except for heulandite (Si:Al < 4.0) and clinoptilolite (Si:Al ??? 4.0). Dehydration, partial hydration, and over-hydration are not sufficient grounds for the recognition of separate species of zeolites. Use of the term 'ideal formula' should be avoided in referring to a simplified or averaged formula of a zeolite. Newly recognized species in compositional series are as follows: brewsterite-Sr.-Ba: chabazite-Ca.-Na.-K; clinoptilolite-K, -Na, -Ca: dachiardite-Ca, -Na; erionite-K, -Ca: faujasite-Na, -Ca, -Na: paulingite-K. -Ca; phillipsite-Na, -Ca, -Ka; stilbite-Ca, -Na. Key references, type locality, origin of name, chemical data. IZA structure-type symbols, space-group symmetry; unit-cell dimensions, and comments on structure are listed for 13 compositional series, 82 accepted zeolite mineral species, and three of doubtful status. Herschelite, leonhardite, svetlozarite, and wellsite are discredited as mineral species names. Obsolete and discredited names are listed.

  11. MODIFICATIONS TO REDUCE DRAG OUT AT A PRINTED CIRCUIT BOARD MANUFACTURER

    EPA Science Inventory

    This MnTAP/EPA Waste Reduction Innovative Technology Evaluation project at Micom, Inc., demonstrated the waste reducing capability of two simple rinsing modifications on an etchant and an electroless copper process. he simple, tow (or no) cost, low technology changes that were ma...

  12. Pecan shell activated carbon: synthesis, characterization, and application for the removal of copper from aqueous solution

    Microsoft Academic Search

    Seyed A Dastgheib; David A Rockstraw

    2001-01-01

    Activated carbon with a high adsorption capacity for removal of copper ions from aqueous solution is produced from pecan shells. Air and phosphoric acid are used for the oxidation and the modification or development of oxygen- or phosphorus\\/oxygen-containing groups on the carbon surface. It was found that the adsorption capacity of the produced carbon is significantly higher than that of

  13. The preparation of lotus-like super-hydrophobic copper surfaces by electroplating

    Microsoft Academic Search

    Wenjun Xi; Zhenmei Qiao; Chunlei Zhu; Ao Jia; Ming Li

    2009-01-01

    The preparation of super-hydrophobic metal surfaces had to combine rough structures and the surface modifications with low surface energy materials. Although there were different views on it, no experiment was done to prove it yet. In this paper, the structure of natural lotus leaf was observed and the lotus-like surfaces on hydrophilic copper substrates were fabricated via electroplating in large

  14. Development of lead-free copper alloy graphite castings. Annual report, January--December 1995

    Microsoft Academic Search

    Rohatgi

    1996-01-01

    The distribution of graphite particles in graphite containing copper alloy was further improved very significantly using several procedures and technological modifications. The developed techniques attacked the graphite distribution problem in two ways. Realizing that clustering of very fine (5um) graphite particles is one of the two major problems, a pretreatment process has been developed using aluminum powders to deagglomerate graphite

  15. Chronic Copper Poisoning in Sheep. 

    E-print Network

    Boughton, I. B. (Ivan Bertrand); Hardy, W. T. (William Tyree)

    1934-01-01

    LIBRARY, - A & M COLLEGE, CAiQFUS. E-109-8M-L180 TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER, DIRECTOR COLLEGE STATION: BRAZOS COUNTY. TEXAS BULLETIN NO. 499 DECEMBER, 1934 DIVISION OF VETERINARY SCIENCE CHRONIC COPPER POISONING... of copper sulphate caused chronic copper poisoning among flocks of range sheep on several West Texas ranches during the past year. The salt licks were placed before the sheep as a means of preventing or controlling stomach worm infestation despite a...

  16. Structure-direction in the crystallization of ITW zeolites using 2-ethyl-1,3,4-trimethylimidazolium.

    PubMed

    Rojas, Alex; Camblor, Miguel A

    2014-07-28

    2-Ethyl-1,3,4-trimethylimidazolium is so far the fifth and largest imidazolium cation able to produce the pure silica zeolite ITW. The crystallization is not direct, but occurs as an in situ transformation from either the chiral HPM-1 (STW) zeolite or the new layered zeolite precursor HPM-2 (preMTF) and results in large interpenetrated crystals with a habit so far unseen in this zeolite. The results of chemical, physicochemical and structural characterization allow us to discuss structure-direction issues. The large cation is occluded intact in the zeolite, causing an expansion of the zeolite volume. The degree of polarization of the Si-O bond is similar to that observed in other as-made ITW zeolites. PMID:24878666

  17. Experimental research of pulsed discharge plasma and TiO2/Zeolite coupling technology for formaldehyde removal

    NASA Astrophysics Data System (ADS)

    Dong, Bingyan; Lan, Shuirong

    2013-03-01

    The pulsed discharge plasma combining with catalyst to remove formaldehyde is a novel type of advanced oxidation technology. In the present work, taking wire-tube pulsed discharge plasma and TiO2/Zeolite coupling technology for formaldehyde removal. The studies have investigated the wire-tube reactor with zeolite, TiO2, TiO2/Zeolite for formaldehyde removal respectively. Results show that in the optimal experimental conditions and the baking time is 120 min, the baking temperature is 450 °C, that TiO2/Zeolite catalyst which made by sol-gel shows higher photocatalytic activity and efficiency. The pulsed discharge with TiO2/Zeolite catalyst for formaldehyde removal has higher removal efficiency than pulsed discharge with zeolite or TiO2. Therefore, pulsed discharge plasma with TiO2/Zeolite for the removal of formaldehyde can greatly increase the removal efficiency.

  18. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  19. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  20. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  1. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  2. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  3. Catalytic degradation of high density polyethylene using zeolites.

    PubMed

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

    2001-01-01

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

  4. Multiple episodes of zeolite deposition in fractured silicic tuff

    SciTech Connect

    Carlos, B.A.; Chipera, S.J.; Snow, M.G.

    1995-04-01

    Fractures in silicic tuffs above the water table at Yucca Mountain, Nevada, USA contain two morphologies of heulandite with different compositions. Tabular heulandite is zoned, with Sr-rich cores and Mg-rich rims. Later prismatic heulandite is nearly the same composition as the more magnesian rims. Heulandite and stellerite may occur between layers of calcite, and calcite occurs locally between generations of heulandite. Thermodynamic modeling, using estimated thermodynamic data and observed chemical compositions for heulandite and stellerite, shows that stellerite is the favored zeolite unless Ca concentrations are reduced or Mg and/or Sr concentrations are significantly elevated above current Yucca Mountain waters.

  5. Raman spectroscopy of iodine molecules trapped in zeolite crystals

    NASA Astrophysics Data System (ADS)

    Guo, Wenhao; Wang, Dingdi; Hu, Juanmei; Tang, Z. K.; Du, Shengwang

    2011-01-01

    We study the Raman spectroscopy of neutral iodine molecules confined in the channels of zeolite AlPO4-5 (AFI) and AlPO4-11 (AEL) crystals, which shows that the molecular vibration states are significantly modified by the confinements from the nanosize channels. An iodine molecule trapped in the AEL crystal has an effective internuclear potential close to an ideal harmonic oscillator, while that in the AFI crystal behaves similarly to that in free space. The results are further confirmed by measuring the temperature dependence of Raman spectral width.

  6. Electron microscopy study of zeolite ZK-14; a synthetic chabazite

    NASA Astrophysics Data System (ADS)

    Cartlidge, S.; Wessicken, R.; Nissen, H.-U.

    1983-03-01

    The defect structure of zeolite (K+, TMA+) — ZK-14, a synthetic chabazite, has been studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM together with TEM bright field (BF) and dark field (DF) micrographs indicate that the hexagonal, platelet ZK-14 crystals are built up of crystalline blocks joined by twinning along (00.1). High resolution transmission electron microscopy (HRTEM) reveals faulting of the ideal AABBCC single 6-ring stacking sequence of ZK-14. This is consistent with an observed line broadening in its X-ray powder diffraction profile. Channel apertures are imaged, even for thick specimens.

  7. Polymorphic copper iodide clusters: insights into the mechanochromic luminescence properties.

    PubMed

    Benito, Quentin; Le Goff, Xavier F; Maron, Sébastien; Fargues, Alexandre; Garcia, Alain; Martineau, Charlotte; Taulelle, Francis; Kahlal, Samia; Gacoin, Thierry; Boilot, Jean-Pierre; Perruchas, Sandrine

    2014-08-13

    An in-depth study of mechanochromic and thermochromic luminescent copper iodide clusters exhibiting structural polymorphism is reported and gives new insights into the origin of the mechanochromic luminescence properties. The two different crystalline polymorphs exhibit distinct luminescence properties with one being green emissive and the other one being yellow emissive. Upon mechanical grinding, only one of the polymorphs exhibits great modification of its emission from green to yellow. Interestingly, the photophysical properties of the resulting partially amorphous crushed compound are closed to those of the other yellow polymorph. Comparative structural and optical analyses of the different phases including a solution of clusters permit us to establish a correlation between the Cu-Cu bond distances and the luminescence properties. In addition, the local structure of the [Cu4I4P4] cluster cores has been probed by (31)P and (65)Cu solid-state NMR analysis, which readily indicates that the grinding process modifies the phosphorus and copper atoms environments. The mechanochromic phenomenon is thus explained by the disruption of the crystal packing within intermolecular interactions inducing shortening of the Cu-Cu bond distances in the [Cu4I4] cluster core and eventually modification of the emissive state. These results definitely establish the role of cuprophilic interactions in the mechanochromism of copper iodide clusters. More generally, this study constitutes a step further into the understanding of the mechanism involved in the mechanochromic luminescent properties of metal-based compounds. PMID:25076411

  8. Removal of copper from ferrous scrap

    DOEpatents

    Blander, M.; Sinha, S.N.

    1990-05-15

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  9. Removal of copper from ferrous scrap

    DOEpatents

    Blander, M.; Sinha, S.N.

    1987-07-30

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  10. Removal of copper from ferrous scrap

    DOEpatents

    Blander, Milton (12833 S. 82nd Ct., Palos Park, IL 60464); Sinha, Shome N. (5748 Drexel, 2A, Chicago, IL 60637)

    1990-01-01

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  11. Steady Deflagration of PBX-9501 Within a Copper Cylinder

    SciTech Connect

    Pemberton, Steven J. [Los Alamos National Laboratory; Herrera, Dennis H. [Los Alamos National Laboratory; Herrera, Tommy J. [Los Alamos National Laboratory; Arellano, Jesus C. [Los Alamos National Laboratory; Sandoval, Thomas D. [Los Alamos National Laboratory

    2012-06-26

    A copper cylinder cook-off experiment has been designed to cause steady deflagration in PBX-9501 explosive material. The design is documented and preliminary copper expansion results are presented for steady deflagration with a reaction speed of 1092 +/- 24 m/s. The expansion of reaction products from the detonation of an explosive is something that is well understood, and reasonably simulated using documented equations of state (EOS) for many explosives of interest. These EOS were historically measured using a 'standard' copper cylinder test design; this design comprised an annealed, oxygen-free high conductivity (OFHC) copper tube filled with explosive material and detonated from one end. Expansion of the copper wall was measured as a function of time using either a streak camera (for classic testing), or more recently using laser velocimetry techniques. Expansion data were then used to derive the EOS in various preferred forms - which are not discussed here for the sake of brevity. [Catanach, et. al., 1999] When an explosive deflagrates rather than detonating, simulation becomes more difficult. Reaction products are released on a slower time scale, and the reactions are much more affected by the geometry and local temperature within the reaction environment. It is assumed that the standard, documented EOS will no longer apply. In an effort to establish a first order approximation of deflagration product behavior, a cook-off test has been designed to cause steady deflagration in PBX-9501 explosive material, and to record the copper expansion profile as a function of time during this test. The purpose of the current paper is to document the initial test design and report some preliminary results. A proposal for modification of the design is also presented.

  12. Copper and Copper Oxide Nanoparticle Formation by Chemical Vapor Nucleation From Copper (II) Acetylacetonate

    Microsoft Academic Search

    Albert G. Nasibulin; P. Petri Ahonen; Olivier Richard; Esko I. Kauppinen; Igor S. Altman

    2001-01-01

    Crystalline nanometer-size copper and copper (I) oxide particle formation was studied by thermal decomposition of copper acetylacetonate Cu(acac)2 vapor using a vertical flow reactor at ambient nitrogen pressure. The experiments were performed in the precursor vapor pressure range of Pprec = 0.06 to 44 Pa at furnace temperatures of 431.5°C, 596.0°C, and 705.0°C. Agglomerates of primary particles were formed at

  13. Direct gold and copper wires bonding on copper

    Microsoft Academic Search

    Hong Meng Ho; Wai Lam; Serguei Stoukatch; Petar Ratchev; Charles J. Vath; Eric Beyne

    2003-01-01

    The key to bonding to copper die is to ensure bond pad cleanliness and minimum oxidation during wire bonding process. This has been achieved by applying a organic coating layer to protect the copper bond pad from oxidation. During the wire bonding process, the organic coating layer is removed and a metal to metal weld is formed. This organic layer

  14. Facile preparation of superhydrophobic copper surface by HNO 3 etching technique with the assistance of CTAB and ultrasonication

    Microsoft Academic Search

    Lining Pan; Huiru Dong; Pengyu Bi

    2010-01-01

    Superhydrophobic rough structure was prepared on copper wafer via HNO3 etching technique with the assistance of Cetyltrimethyl Ammonium Bromide (CTAB) and ultrasonication. After modification of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FDTES), the copper wafer showed stable superhydrophobicity. The morphologies, chemical compositions and hydrophobicity of the substrates were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. Dense and

  15. Direct Growth of Hydroxy Cupric Phosphate Heptahydrate Monocrystal with HoneycombLike Porous Structures on Copper Surface Mimicking Lotus Leaf

    Microsoft Academic Search

    Xin Hua Chen; Guang Bin Yang; Ling Hao Kong; Dong Dong; Lai Gui Yu; Jian Min Chen; Ping Yu Zhang

    2009-01-01

    Superhydrophobic surfaces were prepared on copper foils via a facile assistant surface oxidation technology and subsequent chemical modification with low free energy materials. The three-dimensional (3D) honeycomb-like porous structures made up of nanoslices of hydroxy cupric phosphate heptahydrate (Cu8(PO3OH)2(PO4)4 · 7H2O) single crystals were constructed by immersing copper foil in an aqueous solution of phosphoric acid and hydrogen peroxide. The

  16. Microdensitometer electronics modification

    NASA Technical Reports Server (NTRS)

    Hewitt, A. V.

    1984-01-01

    Minor modifications of electronic components in the PDS 1010A microdensitometer are discussed. The operational requirements and performance limitations of the PDS are noted. Replacement of the photomultiplier and front-end analog circuitry significantly improved the photometric performance of the PDS. The improvement in density repeatability is marked, and the permissible density slew speed is greatly increased.

  17. Instructional Improvement: Behavior Modification.

    ERIC Educational Resources Information Center

    Haring, Norris G.; Hayden, Alice H.

    Sixteen papers are provided. B. F. Skinner discusses the arrangement of contingencies for learning: Lloyd Homme describes behavioral engineering; and Frank Hewett considers behavior modification in special education. Also treated are experimental education by Norris Haring, program evaluation by Arthur Lumsdaine, and administration of special…

  18. Toy Modification Note. Revised.

    ERIC Educational Resources Information Center

    Vanderheiden, Gregg C.; And Others

    Described are toy modifications which enable handicapped individuals to operate battery-powered toys. A battery interrupter is explained as a device which fits between the batteries in a toy and provides the ability to have a separate on-off switch which can be custom designed to fit a handicapped user's needs. Construction and use of three types…

  19. Inborn errors of copper metabolism.

    PubMed

    Kaler, Stephen G

    2013-01-01

    Two copper-transporting ATPases are essential for mammalian copper homeostasis: ATP7A, which mediates copper uptake in the gastrointestinal tract and copper delivery to the brain, and ATP7B, which mediates copper excretion by the liver into bile. Mutations in ATP7A may cause three distinct X-linked conditions in infants, children, or adolescents: Menkes disease, occipital horn syndrome (OHS), and a newly identified allelic variant restricted to motor neurons called X-linked distal hereditary motor neuropathy. These three disorders show variable neurological findings and ages of onset. Menkes disease presents in the first several months of life with failure to thrive, developmental delay, and seizures. OHS features more subtle developmental delays, dysautonomia, and connective tissue abnormalities beginning in early childhood. ATP7A-related distal motor neuropathy presents even later, often not until adolescence or early adulthood, and involves a neurological phenotype that resembles Charcot-Marie-Tooth disease, type 2. These disorders may be treatable through copper replacement or ATP7A gene therapy. In contrast, mutations in ATP7B cause a single known phenotype, Wilson disease, an autosomal recessive trait that results from copper overload rather than deficiency. Dysarthria, dystonia, tremor, gait abnormalities, and psychiatric problems may be presenting symptoms, at ages from 10 to 40 years. Excellent treatment options exist for Wilson disease, based on copper chelation. In the past 2 years (2012-2013), three new autosomal recessive copper metabolism conditions have been recognized: 1) Huppke-Brendel syndrome caused by mutations in an acetyl CoA transporter needed for acetylation of one or more copper proteins, 2) CCS deficiency caused by mutations in the copper chaperone to SODI, and 3) MEDNIK syndrome, which revealed that mutations in the ?1A subunit of adaptor protein complex 1 (AP-1) have detrimental effects on trafficking of ATP7A and ATP7B. PMID:23622398

  20. Improving ammonium and nitrate release from urea using clinoptilolite zeolite and compost produced from agricultural wastes.

    PubMed

    Omar, Latifah; Ahmed, Osumanu Haruna; Ab Majid, Nik Muhamad

    2015-01-01

    Improper use of urea may cause environmental pollution through NH3 volatilization and NO3 (-) leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4 (+) and NO3 (-) release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4 (+) and NO3 (-) losses from urea. Bekenu Series soil (Typic Paleudults) was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH4 (+) and NO3 (-) release from urea (soil incubation study) compared with urea alone, thus reducing leaching of these ions. Ammonium and NO3 (-) leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH4 (+) retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. These observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH4 (+) and NO3 (-) release from urea. PMID:25793220

  1. Spectroscopic evidence for a persistent benzenium cation in zeolite H-beta.

    PubMed

    Bjørgen, Morten; Bonino, Francesca; Kolboe, Stein; Lillerud, Karl-Petter; Zecchina, Adriano; Bordiga, Silvia

    2003-12-24

    Experimental evidence of protonation of an aromatic ring by a zeolite is hereby presented for the first time. The changes in vibrational properties and electronic transitions of the highest polymethylbenzene homologue, that is, hexamethylbenzene, were investigated after introducing the compound directly into a H-beta zeolite. Protonation of the aromatic ring, and thus the loss of symmetry, activated a vibrational ring mode at 1600 cm(-)(1). Furthermore, an electronic transition around 26 000 cm(-)(1), which was totally absent for the neutral species, was an obvious consequence of protonation. A parallel study of hexamethylbenzene adsorbed on a beta zeolite virtually free from protons did not show those distinctive spectral features. On the basis of the gas-phase proton affinity of hexamethylbenzene, a complete proton transfer from the zeolite framework to the molecule is, according to conventional considerations, not expected. The hexamethylbenzenium ion is stable in the zeolite cavities at least up to 200 degrees C. The remarkable persistence of this carbenium ion may be attributed to spatial constraints imposed by the tight fit of the cation inside the zeolite channels. Hexamethylbenzene is a relevant reaction intermediate in the methanol-to-hydrocarbons reaction and also plays a central role as a coke precursor in zeolite-catalyzed reactions that involve polymethylbenzenes. PMID:14677978

  2. Effect of acidic properties of mesoporous zeolites supporting pt nanoparticles on hydrogenative conversion of methylcyclopentane.

    PubMed

    Na, Kyungsu; Alayoglu, Selim; Ye, Rong; Somorjai, Gabor A

    2014-12-10

    The effect of acidic properties of mesoporous zeolites on the control of product selectivity during the hydrogenative isomerization of methylcyclopentane has been investigated. A series of mesoporous zeolites with controlled acidic properties were prepared by postdealumination process with hydrochloric acid under hydrothermal conditions, and the resultant zeolites used for supporting colloidal Pt nanoparticles (NPs) with a mean size of 2.5 nm (± 0.6 nm). As compared to the pure Pt NPs supported on catalytically inert mesoporous silica (MCF-17) as the reference catalyst that can produce isomers most selectively (?80%), the Pt NPs supported on mesoporous zeolites produced C6-cyclic hydrocarbons (i.e., cyclohexane and benzene) most dominantly. The type and strength of the Brönsted (B) and Lewis (L) acid sites of those zeolites with a controlled Al amount are analyzed by using FT-IR after the adsorption of pyridine and NH3 temperature-programmed desorption measurements, and they are correlated with the selectivity change between cyclohexane and benzene. From this investigation, we found a linear relationship between the number of Brönsted acid sites and the formation rate for cyclohexane. In addition, we revealed that more Lewis acidic zeolite having relatively smaller B/L ratio is effective for the cyclohexane formation, whereas more Brönsted acidic zeolite having relatively larger B/L ratio is effective for the benzene formation. PMID:25398051

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

    SciTech Connect

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

    1993-09-01

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

  4. Improving Ammonium and Nitrate Release from Urea Using Clinoptilolite Zeolite and Compost Produced from Agricultural Wastes

    PubMed Central

    Omar, Latifah; Ahmed, Osumanu Haruna; Majid, Nik Muhamad Ab.

    2015-01-01

    Improper use of urea may cause environmental pollution through NH3 volatilization and NO3? leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4+ and NO3? release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4+ and NO3? losses from urea. Bekenu Series soil (Typic Paleudults) was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH4+ and NO3? release from urea (soil incubation study) compared with urea alone, thus reducing leaching of these ions. Ammonium and NO3? leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH4+ retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. These observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH4+ and NO3? release from urea. PMID:25793220

  5. Recovery of oxygenated ignitable liquids by zeolites, Part II: Dual-mode heated passive headspace extraction.

    PubMed

    Rodgers, Corissa L; St Pierre, Kathryne A; Hall, Adam B

    2014-07-01

    Previous studies performed by our research group have suggested that zeolites are a suitable adsorbent for the recovery of oxygenates from fire debris through heated passive headspace extraction. Zeolite 13X, in particular, has been shown to be effective for recovering analytes with molecular diameters smaller than 10Å. The primary aim of this study was to evaluate the addition of zeolite 13X to heated headspace extraction for the recovery of ignitable liquids. Comparative recoveries of petroleum and alcohol-based ignitable liquid mixtures were studied utilizing activated charcoal strips and zeolites, individually and in tandem. In the presence of both adsorption media within the same sample can, activated charcoal strips recovered the majority of gasoline components, while zeolites recovered the majority of oxygenated compounds. This phenomenon was attributed to the size exclusion properties, polarity, and available surface area of zeolites. This research supports the use of zeolites with activated charcoal strips in a "dual-mode" preparation for casework in which the presence of an ignitable liquid is suspected. The described method allows for the recovery and concentration of ignitable liquid residues in a single extraction procedure, whether the ignitable liquid is petroleum-based or oxygenated in nature. PMID:24811978

  6. Copper and zinc recycling from copper alloys` spent pickling solutions

    SciTech Connect

    Roman-Moguel, G.J.; Plascencia, G.; Perez, J.

    1995-12-31

    The precipitation of copper and zinc as cements from a copper alloys` spent pickling solution has been studied at laboratory and pilot scale, with the objective of designing an economic process to recover both metals and render a solution to be either recycled to the pickling process or treated in a standard fashion and produce a non-hazardous sludge. The sulfuric acid spent pickling solution already containing copper and zinc was used first to dissolve another solid residue originated in the copper alloys foundry to neutralize part of the acidity. The resulting enriched solution was treated separately with two reductants: sodium borohydride and iron powder varying pH and excess of reductant under constant agitation. Under the best conditions, precipitation of over 95 percent of zinc and copper was achieved together with the reduction of lead and cadmium contents respectively. A process for the combined residues treatment is proposed.

  7. Oxides of copper, ceria promoted copper, manganese and copper manganese on Al 2O 3 for the combustion of CO, ethyl acetate and ethanol

    Microsoft Academic Search

    Per-Olof Larsson; Arne Andersson

    2000-01-01

    Combustion of CO, ethyl acetate and ethanol was studied over CuOx\\/Al2O3, CuOx–CeO2\\/Al2O3, CuMn2O4\\/Al2O3 and Mn2O3\\/Al2O3 catalysts. It was found that modification of the alumina with ceria before subsequent copper oxide deposition increases the activity for combustion of CO substantially, but the effect of ceria was small on the combustion of ethyl acetate and ethanol. The activity increases with the CuOx

  8. In situ infrared molecular detection using palladium-containing zeolite films.

    PubMed

    Thomas, Sébastien; Bazin, Philippe; Lakiss, Louwanda; de Waele, Vincent; Mintova, Svetlana

    2011-12-01

    In situ IR detection of carbon monoxide in the presence of hydrocarbons (methanol and pentane) using Pd-containing zeolite thin films is reported. The thin films are prepared by spin coating deposition of nanosized LTL and BEA type zeolites suspensions; the palladium clusters are introduced in the nanosized zeolites by ion exchange followed by ? radiolysis of the coating suspensions. The Pd-containing zeolite films with a thickness of 200 nm are exposed to a single gas (either CO or hydrocarbons) or gas mixtures in the presence of water (100 ppm), and the IR spectra are collected continuously at 25, 75, and 100 °C. The fast recognition of very low concentrations of CO (2-100 ppm) in the presence of highly concentrated vapors of methanol or pentane (400-4000 ppm) with the Pd-containing zeolite films is demonstrated. The detection of CO and hydrocarbons is instant, which is a function of the low thickness of the films, small size of the individual zeolite crystals, and regular size and high stability of the Pd clusters in the zeolite films. The heat of adsorption for all experiments is similar (15 kJ.mol(-1)), which is explained with weak interactions between the carbon monoxide and palladium clusters in the zeolite films at temperatures below 100 °C. The nanosized zeolites with homogeneously distributed Pd clusters deposited in thin films demonstrate high molecular recognition capacity toward low concentrations of carbon monoxide under real environmental conditions, i.e., in the presence of water and hydrocarbons. PMID:21981338

  9. Dispersion and orientation of zeolite ZSM-5 crystallites within a fluid catalytic cracking catalyst particle.

    PubMed

    Sprung, Christoph; Weckhuysen, Bert M

    2014-03-24

    Confocal fluorescence microscopy was employed to selectively visualize the dispersion and orientation of zeolite ZSM-5 domains inside a single industrially applied fluid catalytic cracking (FCC) catalyst particle. Large ZSM-5 crystals served as a model system together with the acid-catalyzed fluorostyrene oligomerization reaction to study the interaction of plane-polarized light with these anisotropic zeolite crystals. The distinction between zeolite and binder material, such as alumina, silica, and clay, within an individual FCC particle was achieved by utilizing the anisotropic nature of emitted fluorescence light arising from the entrapped fluorostyrene-derived carbocations inside the zeolite channels. This characterization approach provides a non-invasive way for post-synthesis characterization of an individual FCC catalyst particle in which the size, distribution, orientation, and amount of zeolite ZSM-5 aggregates can be determined. It was found that the amount of detected fluorescence light originating from the stained ZSM-5 aggregates corresponds to about 15?wt?%. Furthermore, a statistical analysis of the emitted fluorescence light indicated that a large number of the ZSM-5 domains appeared in small sizes of about 0.015-0.25??m(2), representing single zeolite crystallites or small aggregates thereof. This observation illustrated a fairly high degree of zeolite dispersion within the FCC binder material. However, the highest amount of crystalline material was aggregated into larger domains (ca. 1-5??m(2)) with more or less similarly oriented zeolite crystallites. It is clear that this visualization approach may serve as a post-synthesis quality control on the dispersion of zeolite ZSM-5 crystallites within FCC particles. PMID:24616006

  10. Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts.

    PubMed

    Choi, Minkee; Na, Kyungsu; Kim, Jeongnam; Sakamoto, Yasuhiro; Terasaki, Osamu; Ryoo, Ryong

    2009-09-10

    Zeolites-microporous crystalline aluminosilicates-are widely used in petrochemistry and fine-chemical synthesis because strong acid sites within their uniform micropores enable size- and shape-selective catalysis. But the very presence of the micropores, with aperture diameters below 1 nm, often goes hand-in-hand with diffusion limitations that adversely affect catalytic activity. The problem can be overcome by reducing the thickness of the zeolite crystals, which reduces diffusion path lengths and thus improves molecular diffusion. This has been realized by synthesizing zeolite nanocrystals, by exfoliating layered zeolites, and by introducing mesopores in the microporous material through templating strategies or demetallation processes. But except for the exfoliation, none of these strategies has produced 'ultrathin' zeolites with thicknesses below 5 nm. Here we show that appropriately designed bifunctional surfactants can direct the formation of zeolite structures on the mesoporous and microporous length scales simultaneously and thus yield MFI (ZSM-5, one of the most important catalysts in the petrochemical industry) zeolite nanosheets that are only 2 nm thick, which corresponds to the b-axis dimension of a single MFI unit cell. The large number of acid sites on the external surface of these zeolites renders them highly active for the catalytic conversion of large organic molecules, and the reduced crystal thickness facilitates diffusion and thereby dramatically suppresses catalyst deactivation through coke deposition during methanol-to-gasoline conversion. We expect that our synthesis approach could be applied to other zeolites to improve their performance in a range of important catalytic applications. PMID:19741706

  11. Optimum conditions for fabricating superhydrophobic surface on copper plates via controlled surface oxidation and dehydration processes

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Li, Wen; Ma, Fumin; Yu, Zhanlong; Ruan, Min; Ding, Yigang; Deng, Xiangyi

    2013-09-01

    The superhydrophobic surfaces on copper substrate were fabricated by direct oxidation and dehydration processes, and the reaction and modification conditions were optimized. Firstly, the oxidation conditions including the concentrations of K2S2O8 and NaOH, the oxidation time were studied. It is found that the superhydrophobicity would be better if the copper plates were oxidized in 0.06 M K2S2O8 and 3.0 M NaOH solution at 65 °C for 35 min. Then, the modification conditions including modifier concentration and modification time were investigated. The results showed that 5 wt% lauric acid and 1 h modification time were suitable modification conditions for preparing copper-based superhydrophobic surfaces. The surface fabricated under optimized conditions displayed excellent superhydrophobicity of high water contact angle of 161.1° and a low contact angle hysteresis of 2.5°. The surface microstructure and composition of the superhydrophobic surfaces were also characterized by SEM and FT-IR. It is found that the highly concentrated micro/nanostructured sheets and the low surface energy materials on the surface should be responsible for the high superhydrophobicity.

  12. Synthesis of hyacinth, vanilla, and blossom orange fragrances: the benefit of using zeolites and delaminated zeolites as catalysts

    Microsoft Academic Search

    Maria José Climent; Avelino Corma; Alexandra Velty

    2004-01-01

    The synthesis of phenylacetaldehyde glycerol acetals, 2-benzyl-4-hydroxymethyl-1,3-dioxolane (1), 2-benzyl-5-hydroxy-1,3-dioxane (2), and vanillin propylene glycol acetal (2-(4-hydroxy-3-methoxyphenyl)-4-methyl-1,3-dioxolane) (3) which are flavoring compounds with hyacinth and vanilla scent fragrances, have been carried out successfully by acetalization of phenylacetaldehyde and vanillin with glycerol and propylene glycol, respectively, using toluene as solvent and zeolite catalysts whose adsorption properties have been optimized. However, in the

  13. Picosecond laser induced periodic surface structure on copper thin films

    NASA Astrophysics Data System (ADS)

    Huynh, Thi Trang Dai; Petit, Agnès; Semmar, Nadjib

    2014-05-01

    LIPSS (Laser Induced Periodic Surface Structure) formation on copper thin films induced by a picosecond laser beam (Nd:YAG laser at 266 nm, 42 ps and 10 Hz) was studied experimentally. Copper thin films were deposited on glass and silicon substrates by magnetron sputtering. The surface modifications of irradiated zones were analyzed by scanning electron microscopy. Two distinct types of LIPSS were identified with respect to the laser fluence (F), number of laser shots (N) and substrate material. Namely, with a number of laser shots (1000 < N < 10,000) and a fluence of (200 mJ/cm2 < F < 500 mJ/cm2), Low Spatial Frequency LIPSS (LSFL with a spatial period of ? ? 260 nm and an orientation perpendicular to polarization) and High Spatial Frequency LIPSS (HSFL with a spatial period of ? ? 130 nm and an orientation parallel to the polarization) were observed. The regime of regular spikes formation was determined for N ? 1000. Moreover, the 2D-map of the relationship among LIPSS formation, laser fluence and number of laser shots on copper thin film with two different substrates was established. A physics interpretation of regular spikes and LIPSS formation on copper thin film induced by ps laser with overlapping multi-shots is proposed based on experimental data and the theory of Plateau-Rayleigh instability.

  14. Removal of heavy metals from acid mine drainage (AMD) using coal fly ash, natural clinker and synthetic zeolites.

    PubMed

    Ríos, C A; Williams, C D; Roberts, C L

    2008-08-15

    Acid mine drainage (AMD) is a widespread environmental problem associated with both working and abandoned mining operations, resulting from the microbial oxidation of pyrite in presence of water and air, affording an acidic solution that contains toxic metal ions. The generation of AMD and release of dissolved heavy metals is an important concern facing the mining industry. The present study aimed at evaluating the use of low-cost sorbents like coal fly ash, natural clinker and synthetic zeolites to clean-up AMD generated at the Parys Mountain copper-lead-zinc deposit, Anglesey (North Wales), and to remove heavy metals and ammonium from AMD. pH played a very important role in the sorption/removal of the contaminants and a higher adsorbent ratio in the treatment of AMD promoted the increase of the pH, particularly using natural clinker-based faujasite (7.70-9.43) and the reduction of metal concentration. Na-phillipsite showed a lower efficiency as compared to that of faujasite. Selectivity of faujasite for metal removal was, in decreasing order, Fe>As>Pb>Zn>Cu>Ni>Cr. Based on these results, the use of these materials has the potential to provide improved methods for the treatment of AMD. PMID:18221835

  15. Minimizing iron and copper deposition

    Microsoft Academic Search

    1975-01-01

    A major cause of tube failures in high-pressure subcritical boilers is uncontrolled deposition of corrosion products in internal tube surfaces. The predominant corrosion products are iron oxides, copper, and copper oxides. A water treatment program that controls corrosion products can increase availability and reliability by reducing tube failures and acid cleaning frequency. Such a program includes corrosion product dispersion in

  16. Copper deficiency mimicking myelodysplastic syndrome

    PubMed Central

    Dalal, Neil; Hooberman, Arthur; Mariani, Rachel; Sirota, Ronald; Lestingi, Timothy

    2015-01-01

    Key Clinical Message Copper deficiency is a rare cause of pancytopenia that may be mistaken for myelodysplastic syndrome. Cytoplasmic vacuolization in erythroid and myeloid precursors is found on bone marrow examination. Patients with a history of abdominal surgery who present with anemia and neutropenia with dysplastic changes should have copper levels checked. PMID:25984314

  17. Copper Substrate Catalyzes Tetraazaperopyrene Polymerization

    E-print Network

    Schmidt, Wolf Gero

    Copper Substrate Catalyzes Tetraazaperopyrene Polymerization W.G. Schmidt, E. Rauls, U. Gerstmann-up approach, appears to be a very promising way to fabricate functional systems with nanometer dimensions [1 found that the copper substrate is crucial for the formation of the various aggregates they observed, i

  18. Advanced copper wire bonding technology

    Microsoft Academic Search

    Hong Meng Ho

    2010-01-01

    Wire bonding is the most dominant form of first-level chip interconnects in microelectronics with gold wire bonding taking the lead for the past few decades. Today, it is evident that the shift from gold to copper wire bonding is genuinely picking up, due to both a surge in gold prices and recent developments in copper wire bonding technology. The course

  19. The Work Function of Copper

    Microsoft Academic Search

    Paul A. Anderson

    1949-01-01

    The work functions and aging characteristics of fourteen copper surfaces have been determined by measurement of their contact differences of potential with respect to barium reference surfaces of known work function. Measurement was by the retarding potential method in tubes sealed from the pumps and gettered with vaporized barium. The copper surfaces were prepared by subjecting Hilger's \\

  20. Copper inhibits beta-amyloid production and stimulates the non-amyloidogenic pathway of amyloid-precursor-protein secretion.

    PubMed Central

    Borchardt, T; Camakaris, J; Cappai, R; Masters, C L; Beyreuther, K; Multhaup, G

    1999-01-01

    Previous studies have demonstrated that amyloid precursor protein (APP) can bind and reduce Cu(II) to Cu(I), leading to oxidative modification of APP. In the present study we show that adding copper to Chinese-hamster ovary (CHO) cells greatly reduced the levels of amyloid Abeta peptide (Abeta) both in parental CHO-K1 and in copper-resistant CHO-CUR3 cells, which have lower intracellular copper levels. Copper also caused an increase in the secretion of the APP ectodomain, indicating that the large decrease in Abeta release was not due to a general inhibition in protein secretion. There was an increase in intracellular full-length APP levels which paralleled the decrease in Abeta generation, suggesting the existence of two distinct regulating mechanisms, one acting on Abeta production and the other on APP synthesis. Maximal inhibition of Abeta production and stimulation of APP secretion was achieved in CHO-K1 cells at about 10 microM copper and in CHO-CUR3 cells at about 50 microM copper. This dose 'window of opportunity' at which copper promoted the non-amyloidogenic pathway of APP was confirmed by an increase in the non-amyloidogenic p3 fragment produced by alpha-secretase cleavage. Our findings suggest that copper or copper agonists might be useful tools to discover novel targets for anti-Alzheimer drugs and may prove beneficial for the prevention of Alzheimer's disease. PMID:10567229

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

    SciTech Connect

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

    1982-01-01

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

  2. Thorium removal from aqueous solutions of Mexican erionite and X zeolite

    Microsoft Academic Search

    M. G. Salinas-Pedroza; M. T. Olguín

    2004-01-01

    Thorium(IV) removal from aqueous solutions by erionite and X zeolite was investigated. The Th(IV) uptake at different thorium\\u000a nitrate concentrations (from 0.25 to 25 mM) was evaluated. The thorium content in the aqueous solution was determined by neutron\\u000a activation analysis. Th(IV) retained by zeolites was 1.7 and 3.7 meq\\/g for erionite and X zeolite. In order to explain the\\u000a thorium

  3. Nature of condensation products in but-1-ene aromatization on high-silica zeolite catalyst

    NASA Astrophysics Data System (ADS)

    Mirzai, C. I.; Hashimov, F. A.; Kozharov, A. I.; Talybova, Z. A.; Nadyrov, P. A.

    2013-09-01

    The aromatization of but-1-ene on the H-form of pentasil-type zeolite catalyst (SiO2/Al2O3 = 54) is studied in the temperature range from 573 to 723 K. It is shown that in the range of 623 to 723 K, the liquid phase consists mainly of aromatic hydrocarbons. The results from differential thermal and X-ray diffraction analyses show that graphite-like depositions can form in zeolite channels during the conversion of but-1-ene on the H-form of zeolite catalyst at 673 K and more than 20 h. The activity of the catalyst remains virtually the same.

  4. Effects of copper(II) and copper oxides on THMs formation in copper pipe.

    PubMed

    Li, Bo; Qu, Jiuhui; Liu, Huijuan; Hu, Chengzhi

    2007-08-01

    Little is known about how the growth of trihalomethanes (THMs) in drinking water is affected in copper pipe. The formation of THMs and chlorine consumption in copper pipe under stagnant flow conditions were investigated. Experiments for the same water held in glass bottles were performed for comparison. Results showed that although THMs levels firstly increased in the presence of chlorine in copper pipe, faster decay of chlorine as compared to the glass bottle affected the rate of THMs formation. The analysis of water phase was supplemented by surface analysis of corrosion scales using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX). The results showed the scales on the pipe surface mainly consisted of Cu(2)O, CuO and Cu(OH)(2) or CuCO(3). Designed experiments confirmed that the fast depletion of chlorine in copper pipe was mainly due to effect of Cu(2)O, CuO in corrosion scales on copper pipe. Although copper(II) and copper oxides showed effect on THMs formation, the rapid consumption of chlorine due to copper oxide made THM levels lower than that in glass bottles after 4h. The transformations of CF, DCBM and CDBM to BF were accelerated in the presence of copper(II), cupric oxide and cuprous oxide. The effect of pH on THMs formation was influenced by effect of pH on corrosion of copper pipe. When pH was below 7, THMs levels in copper pipe was higher as compared to glass bottle, but lower when pH was above 7. PMID:17363030

  5. Mass-transport characteristics of zeolite cracking catalysts. Final report

    SciTech Connect

    Haynes, H.W. Jr.

    1981-01-07

    Three series of experiments were undertaken in this investigation. In the first study we attempted to measure the intracrystalline diffusivities of a variety of alkanes and naphthenic hydrocarbons in zeolite NaY by the gas chromatography technique. The results were only partially successful. In the second investigation mixtures of two-, three-, and four-ring (naphthalene, phenanthrene, and pyrene) structures were hydrocracked over a nickel-tungsten sulfide ultrastable zeolite Y catalyst. The catalyst was very active in hydrocracking all three structures. At 371/sup 0/C and 10,440 kPa the pseudo first order rate constants (gm/hr/gm) for hydrocracking the two-, three- and four-ring mixtures were 14/6.2/2.8 respectively. In the third experimental investigation three molecular species (n-heptane, decalin, and 1-methyldecalin) of varying critical diameter were cracked over several acid faujasites (LaNaY, LaHY, MgHY, USY) of varying catalytic activity. For comparison purposes the hydrocarbons were also cracked over an amorphous silica-alumina catalyst. The experiments were carried out in a flow reactor in the presence of inert carrier (helium) at near atmospheric pressure and consequently the conditions more nearly approximate catalytic cracking conditions in contrast to the catalytic hydrocracking study described above. The naphthenic hydrocarbons were chosen for this study because it was demonstrated during preliminary work that the cracking kinetics was first order. Detailed reports of the three experiments are included in this final report.

  6. Catalytic cracking of a Gippsland reduced crude on zeolite catalysts

    SciTech Connect

    Guerzoni, F.N.; Abbot, J. (Univ. of Tasmania (Australia))

    1994-06-01

    Cracking reactions of a Gippsland reduced crude have been investigated at 520[degrees]C over HY and HZSM-5. Gasolines with similar characteristics can be obtained on both zeolites, although the mechanistic routes to these products are quite distinct. Changes in aromatic product selectivities are consistent with the zeolite pore geometries. Minor quantities of aromatics are formed via hydrogen transfer processes involving product olefins and naphthenes over the faujasite and the cyclization (and to a lesser extent oligomerization) of olefinic species on the pentasil. Dehydrogenation of naphthenic species in the feedstock is also important for aromatic formation. While paraffins are formed via hydrogen transfer processes together with cracking and isomerization of feed paraffins on HY, only the latter route can explain formation of saturated species on HZSM-5. The removal of linear paraffins from the GRC was traced as a function of conversion on HY. It was found that the relative reactivity of the linear paraffins increased monotonically with paraffin chain length. 43 refs., 11 figs., 8 tabs.

  7. Influence of polyelectrolytes on crystallization of zeolite Y

    NASA Astrophysics Data System (ADS)

    Köro?lu, Hansu Jülide; Hande Öz, Pembe; Nusret Bulutçu, A.

    2012-09-01

    In this study, the influence of polyelectrolytes on the crystallization of zeolite Y is investigated. The prepared synthesis mixtures are aged at room temperature for 24 h and then left to crystallize. The compositional and structural information are provided by elemental analysis obtained by ICP, X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), particle size analyzer and adsorption and desorption isotherms of nitrogen by a volumetric adsorption instrument. The first group of synthesis studies is conducted by using solutions containing no additive (WA), nonionic (NI), 100% anionic (100A), and 100% cationic (100C) polyelectrolytes. The crystallization temperature and crystallization time are kept at 100 ºC and 48 h, respectively. The experimental results show that nonionic polyelectrolyte has the most influence on the crystallization of zeolite NaY. In the second group of synthesis studies, the effects of polyelectrolytes with various degrees of anionic properties (10%, 50% and 70%) of the same chemical structure are investigated by conducting crystallization experiments at 100 °C for a duration of 48 h. The results suggest that; particle size, crystallinity and BET surface area (SBET) can be controlled by adding anionic polyelectrolytes to the solution.

  8. Adsorption of isobutane on H-TsVM zeolite

    NASA Astrophysics Data System (ADS)

    Kipnis, M. A.; Samokhin, P. V.; Yashina, O. V.; Sukhorebrova, O. A.

    2013-05-01

    A procedure was developed for evaluating the adsorption of hydrocarbons on solids by monitoring the temperature of the gas over the sample layer and inside it, the heat conductivity of the gas at the inlet and outlet of the flow reactor, and the composition of the gas after the sample. The adsorption-desorption of isobutane accompanied by heat liberation or absorption (recorded as a temperature change in the zeolite layer) was studied using the H-TsVM zeolite as an example. The temperature effects during isobutane adsorption and desorption were compared. It was concluded that below ˜90°C, some part of isobutane is significantly chemisorbed on H-TsVM. The highly adsorbed isobutane can be removed by keeping the sample in a nitrogen flow for a long time or by heating it above 90°C. Time dependence of isobutane desorption at constant temperature can be described by first order kinetic equation, making possible to estimate the activation energy of desorption of highly chemisorbed isobutane using the data on thermodesorption at linear temperature increase.

  9. Cation exchange properties of zeolites in hyper alkaline aqueous media.

    PubMed

    Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

    2015-02-01

    Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media. PMID:25569300

  10. Unraveling the perplexing structure of the zeolite SSZ-57.

    PubMed

    Baerlocher, Christian; Weber, Thomas; McCusker, Lynne B; Palatinus, Lukas; Zones, Stacey I

    2011-08-26

    Previous high-resolution x-ray powder diffraction and transmission electron microscopy studies of the zeolite SSZ-57 could not fully elucidate the structural basis for its puzzling adsorption behavior, which appears to be intermediate between that of a medium- (10-ring) and a large-pore (12-ring) zeolite. Now by applying advanced crystallographic techniques (structure solution in four-dimensional space and interpretation of three-dimensional diffuse scattering by Monte Carlo simulation) and crystal chemistry considerations to high-quality single-crystal x-ray diffraction data collected on a microcrystal (about 2 micrometers by 2 micrometers by 8 micrometers), we have been able to derive a comprehensive description of its silicate framework structure. The framework is related to that of ZSM-11 but is commensurately modulated along the c axis (P4m2, a = b = 20.091 Å, c = 110.056 Å) to yield a structure with a 12-ring:10-ring ratio of 1:15. Disorder of the 12-rings results in a three-dimensional 10-ring channel system with large isolated pockets. The structure helps to clarify the material's catalytic activity. PMID:21868674

  11. Copper chip technology

    NASA Astrophysics Data System (ADS)

    Edelstein, Daniel C.

    1998-08-01

    Recently, IBM announced the first silicon integrated circuit technology that incorporates copper on-chip wiring. This technology, which combines industry-leading CMOS ULSI devices with 6 levels of hierarchically-scaled Cu metallization, has reached the point of manufacturing, after passing the qualification tests required to prove feasibility, yield, reliability, and manufacturability. The discussion of the change from Al to Cu interconnects for ULSI encompasses a wide variety of issues. This paper attempts to address these by way of example, from the broad range of detailed studies that have been performed in the course of developing these so-called 'copper chips'. Motivational issues are covered by comparative modeling of performance aspects and cost. The technology parameters and features are shown, as well as data relating to the process integration, electrical yield and parametric behavior, early manufacturing data, high-frequency modeling and measurements, nose and clock skew. The viability of this technology is indicated by results from reliability stressing, as well as the first successful demonstrations of fully functional SRAM, DRAM, and microprocessor chips with Cu wiring. The advantages of integrated Cu wiring may be applied even more broadly in the future. An example shown here is the achievement of very high-quality integrated inductors; these may help prospects for complete integration of RF and wireless communications chips onto silicon.

  12. Pectin modifications: a review.

    PubMed

    Chen, Jun; Liu, Wei; Liu, Cheng-Mei; Li, Ti; Liang, Rui-Hong; Luo, Shun-Jing

    2015-10-15

    In recent years, the interest in studying modification of pectin has increased. A number of hydroxyl and carboxyl groups distributed along the backbone as well as a certain amount of neutral sugars presented as side chains make pectin capable of preparing a broad spectrum of derivatives. By forming pectin derivatives, their properties may be modified and some other new functional properties may be created. This article attempts to review the information about various methods used for pectin modification, including substitution (alkylation, amidation, quaternization, thiolation, sulfation, oxidation, etc.), chain elongation (cross-linking and grafting) and depolymerization (chemical, physical, and enzymatic degradation). Characteristics and applications of some pectin derivatives are also presented. In addition, the safety and regulatory status of pectin and its derivatives were reviewed. PMID:24798790

  13. Metal-organic and zeolite imidazolate frameworks (MOFs and ZIFs) for highly selective separations

    SciTech Connect

    Omar M. Yaghi

    2012-09-17

    Metal-organic and zeolite imidazolate frameworks (MOFs and ZIFs) have been investigated for the realization as separation media with high selectivity. These structures are held together with strong bonds, making them architecturally, chemically, and thermally stable. Therefore, employing well designed building units, it is possible to discover promising materials for gas and vapor separation. This grant was focused on the study of MOFs and ZIFs with these specific objectives: (i) to develop a strategy for producing MOFs and ZIFs that combine high surface areas with active sites for their use in gas adsorption and separation of small organic compounds, (ii) to introduce active sites in the framework by a post-synthetic modification and metalation of MOFs and ZIFs, and (iii) to design and synthesize MOFs with extremely high surface areas and large pore volumes to accommodate large amounts of guest molecules. By the systematic study, this effort demonstrated how to introduce active functional groups in the frameworks, and this is also the origin of a new strategy, which is termed isoreticular functionalization and metalation. However, a large pore volume is still a prerequisite feature. One of the solutions to overcome this challenge is an isoreticular expansion of a MOF�������¢����������������s structure. With triangular organic linker and square building units, we demonstrated that MOF-399 has a unit cell volume 17 times larger than that of the first reported material isoreticular to it, and it has the highest porosity (94%) and lowest density (0.126 g cm-3) of any MOF reported to date. MOFs are not just low density materials; the guest-free form of MOF-210 demonstrates an ultrahigh porosity, whose BET surface area was estimated to be 6240 m2 g-1 by N2 adsorption measurements.

  14. Genetic modification in floriculture

    Microsoft Academic Search

    Stephen F. Chandler; Filippa Brugliera

    2011-01-01

    Micro-propagation, embryo rescue, mutagenesis via chemical or irradiation means and in vitro inter-specific hybridisation\\u000a methods have been used by breeders in the floriculture industry for many years. In the past 20 years these enabling technologies\\u000a have been supplemented by genetic modification methods. Though many genes of potential utility to the floricultural industry\\u000a have been identified, and much has been learnt of

  15. Fabrication and material characterization of copper and copper–CNT micropillars

    NASA Astrophysics Data System (ADS)

    Ghanbari, S.; Darabi, J.

    2015-07-01

    In this work, copper micropillars and copper–carbon nanotube (CNT) composite micropillars were fabricated by incorporating an electrodeposition technique with a xurography process. In order to disperse carbon nanotubes in copper–CNT micropillars, various amounts of CNTs were added to the electroplating bath. Surface morphology and phase characterization of copper micropillars and copper–CNT composite micropillars were analyzed by optical microscopy and x-ray diffraction. In addition, the corrosion resistance (Rp) of a bare copper substrate, copper micropillars, and optimum copper–CNT micropillars were studied by electrochemical impedance spectroscopy (EIS) technique in a 3.5 wt.% sodium chloride. Experimental results yielded a corrosion resistance of 200 ? cm2 for the bare copper substrate, 400 ? cm2 for copper micropillars, and 2550 ? cm2 for copper–CNT micropillars, indicating a significantly higher corrosion resistance for copper–CNT micropillars due to a lower chemical reactivity and refinement of crystal structure of copper in micropillars.

  16. Zeolite formation from coal fly ash and heavy metal ion removal characteristics of thus-obtained Zeolite X in multi-metal systems.

    PubMed

    Jha, Vinay Kumar; Nagae, Masahiro; Matsuda, Motohide; Miyake, Michihiro

    2009-06-01

    Zeolitic materials have been prepared from coal fly ash as well as from a SiO(2)-Al(2)O(3) system upon NaOH fusion treatment, followed by subsequent hydrothermal processing at various NaOH concentrations and reaction times. During the preparation process, the starting material initially decomposed to an amorphous form, and the nucleation process of the zeolite began. The carbon content of the starting material influenced the formation of the zeolite by providing an active surface for nucleation. Zeolite A (Na-A) was transformed into zeolite X (Na-X) with increasing NaOH concentration and reaction time. The adsorption isotherms of the obtained Na-X based on the characteristics required to remove heavy ions such as Ni(2+), Cu(2+), Cd(2+) and Pb(2+) were examined in multi-metal systems. Thus obtained experimental data suggests that the Langmuir and Freundlich models are more accurate compared to the Dubinin-Kaganer-Radushkevich (DKR) model. However, the sorption energy obtained from the DKR model was helpful in elucidating the mechanism of the sorption process. Further, in going from a single- to multi-metal system, the degree of fitting for the Freundlich model compared with the Langmuir model was favored due to its basic assumption of a heterogeneity factor. The Extended-Langmuir model may be used in multi-metal systems, but gives a lower value for equilibrium sorption compared with the Langmuir model. PMID:19233542

  17. Di-, tri-, tetra-, and hexanuclear copper(II) mono-organophosphates: structure and nuclearity dependence on the choice of phosphorus substituents and auxiliary N-donor ligands.

    PubMed

    Murugavel, Ramaswamy; Kuppuswamy, Subramaniam; Maity, Amarendra Nath; Singh, Mayank Pratap

    2009-01-01

    Reactions of 2,6-dimethylphenyl phosphate (dmppH(2)) and 2,6-diisopropylphenyl phosphate (dippH(2)) with copper(II) precursors have been investigated in the presence of auxiliary N-donor ligands, and new structural types of copper phosphates have been isolated. Copper acetate reacts with dmppH(2) in the presence of either 3,5-di-tert-butyl pyrazole (dbpz) or 3,5-dimethyl pyrazole (dmpz), leading to the isolation of tetrameric complex [Cu(dmpp)(dbpz)](4) 1 and hexanuclear cage complex [Cu(6)(PO(4))(dmpp)(3)(OAc)(3)(dmpz)(9)] 2, respectively. Whereas compound 1 is a cubane-shaped cluster whose Cu(4)O(12)P(4) core resembles the double-4-ring (D4R) zeolite SBU, compound 2 is a novel hexanuclear copper complex with an unprecedented structure in metal phosphate chemistry. Use of bulkier dippH(2) in the above reactions, however, yielded metal-free acid-base complexes [(dippH)(dbpz)(dbpzH)] 3 and [(dippH)(dmpz)(dmpzH)] 4, respectively. The reactions carried out between copper acetate and dmppH(2) or dippH(2) in the presence of chelating ligand 1,10-phenanthroline produced structurally similar dimeric copper phosphates [Cu(phen)(dmpp)(CH(3)OH)](2).2CH(3)OH 5 and [Cu(phen)(dipp)(CH(3)OH)](2).2CH(3)OH 6 with a S4R SBU core. Changing the copper source to [Cu(2)(bpy)(2)(OAc)(OH)(H(2)O)].2ClO(4) and carrying out reactions both with dippH(2) and with dmppH(2) result in the formation of trinuclear copper phosphates [Cu(3)(bpy)(3)(dmpp)(2)(CH(3)OH)(3)].2ClO(4).2CH(3)OH 7 and [Cu(3)(bpy)(3)(dipp)(2)(CH(3)OH)(3)].2ClO(4).2CH(3)OH 8. The three copper ions in 7 and 8 are held together by two bridging phosphate ligands to produce a tricyclic derivative whose core resembles the 4=1 SBU of zeolites. Compounds 1-8 have been characterized by elemental analysis and IR, absorption, emission, and EPR spectroscopic techniques. The crystal structures of compounds 1, 2, 4, 5, 6, and 8 have also been established by single-crystal X-ray diffraction studies. PMID:19049423

  18. Performance of Copper Naphthenate in Fence Posts

    Microsoft Academic Search

    Mike H. Freeman

    This paper reviews the efficacy and field trials of copper naphthenate in various wood species. Included in this discussion are chemical and physical characteristics of copper naphthenate preservative systems, the effect on wood treated with copper naphthenate or copper naphthenate wood preservative systems, and a review of the long-term efficacy trials, in various species of wooden fence posts. Included in

  19. 49 CFR 192.279 - Copper pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Transportation 3 2014-10-01 2014-10-01 false Copper pipe. 192.279 Section 192.279 Transportation...of Materials Other Than by Welding § 192.279 Copper pipe. Copper pipe may not be threaded except that copper...

  20. 49 CFR 192.279 - Copper pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Transportation 3 2010-10-01 2010-10-01 false Copper pipe. 192.279 Section 192.279 Transportation...of Materials Other Than by Welding § 192.279 Copper pipe. Copper pipe may not be threaded except that copper...