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.

Benzene carboxylic acid derivatized graphene oxide nanosheets on natural zeolites as effective adsorbents for cationic dye removal.

PubMed

Yu, Yang; Murthy, Bandaru N; Shapter, Joseph G; Constantopoulos, Kristina T; Voelcker, Nicolas H; Ellis, Amanda V

2013-09-15

Graphene oxide (GO) nanosheets were grafted to acid-treated natural clinoptilolite-rich zeolite powders followed by a coupling reaction with a diazonium salt (4-carboxybenzenediazoniumtetrafluoroborate) to the GO surface. Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) revealed successful grafting of GO nanosheets onto the zeolite surface. The application of the adsorbents for the adsorption of rhodamine B from aqueous solutions was then demonstrated. After reaching adsorption equilibrium the maximum adsorption capacities were shown to be 50.25, 55.56 and 67.56 mg g(-1) for pristine natural zeolite, GO grafted zeolite (GO-zeolite) and benzene carboxylic acid derivatized GO-zeolite powders, respectively. The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. Further, a relationship between surface functional groups, pH and adsorption efficiency was established. Results indicate that benzene carboxylic acid derivatized GO-zeolite powders are environmentally favorable adsorbents for the removal of cationic dyes from aqueous solutions. Copyright © 2013 Elsevier B.V. All rights reserved.

Sedimentation field-flow fractionation for characterization of citric acid-modified Hβ zeolite particles: Effect of particle dispersion and carrier composition.

PubMed

Dou, Haiyang; Bai, Guoyi; Ding, Liang; Li, Yueqiu; Lee, Seungho

2015-11-27

In this study, sedimentation field-flow fractionation (SdFFF) was, for the first time, applied for determination of size distribution of Hβ zeolite particles modified by citric acid (CA-Hβ). Effects of the particle dispersion and the carrier liquid composition (type of dispersing reagent (surfactant) and salt added in the carrier liquid, ionic strength, and pH) on SdFFF elution behavior of CA-Hβ zeolite particles were systematically investigated. Also the SdFFF separation efficiency of the particles was discussed in terms of the forces such as van der Waals, hydrophobic, and induced-dipole interactions. Results reveal that the type of salt and pH of the carrier liquid significantly affect the SdFFF separation efficiency of the zeolite particles. It was found that addition of a salt (NaN3) into the carrier liquid affects the characteristic of the SdFFF channel surface. It was found that the use of an acidic medium (pH 3.2) leads to a particle-channel interaction, while the use of a basic medium (pH 10.6) promotes an inter-particle hydrophobic interaction. Result from SdFFF was compared with those from scanning electron microscopy (SEM) and dynamic light scattering (DLS). It seems that, once the experimental conditions are optimized, SdFFF becomes a valuable tool for size characterization of the zeolite particles. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis of novel perfluoroalkylglucosides on zeolite and non-zeolite catalysts.

PubMed

Nowicki, Janusz; Mokrzycki, Łukasz; Sulikowski, Bogdan

2015-04-08

Perfluoroalkylglucosides comprise a very important class of fluorine-containing surfactants. These compounds can be synthesized by using the Fisher reaction, starting directly from glucose and the required perfluoroalcohols. We wish to report on the use of zeolite catalysts of different structure and composition for the synthesis of perfluoroalkylglucosides when using glucose and 1-octafluoropentanol as substrates. Zeolites of different pore architecture have been chosen (ZSM-5, ZSM-12, MCM-22 and Beta). Zeolites were characterized by XRD, nitrogen sorption, scanning electron microscopy (SEM) and solid-state 27Al MAS NMR spectroscopy. The activity of the zeolite catalysts in the glycosidation reaction was studied in a batch reactor at 100 °C below atmospheric pressure. The performance of zeolites was compared to other catalysts, an ion-exchange resin (Purolite) and a montmorillonite-type layered aluminosilicate. The catalytic performance of zeolite Beta was the highest among the zeolites studied and the results were comparable to those obtained over Purolite and montmorillonite type catalysts.

21 CFR 870.1370 - Catheter tip occluder.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Catheter tip occluder. 870.1370 Section 870.1370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1370 Catheter tip occluder...

21 CFR 870.1370 - Catheter tip occluder.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Catheter tip occluder. 870.1370 Section 870.1370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1370 Catheter tip occluder...

Decoding information about dynamically occluded objects in visual cortex

PubMed Central

Erlikhman, Gennady; Caplovitz, Gideon P.

2016-01-01

During dynamic occlusion, an object passes behind an occluding surface and then later reappears. Even when completely occluded from view, such objects are experienced as continuing to exist or persist behind the occluder, even though they are no longer visible. The contents and neural basis of this persistent representation remain poorly understood. Questions remain as to whether there is information maintained about the object itself (i.e. its shape or identity) or, non-object-specific information such as its position or velocity as it is tracked behind an occluder as well as which areas of visual cortex represent such information. Recent studies have found that early visual cortex is activated by “invisible” objects during visual imagery and by unstimulated regions along the path of apparent motion, suggesting that some properties of dynamically occluded objects may also be neurally represented in early visual cortex. We applied functional magnetic resonance imaging in human subjects to examine the representation of information within visual cortex during dynamic occlusion. For gradually occluded, but not for instantly disappearing objects, there was an increase in activity in early visual cortex (V1, V2, and V3). This activity was spatially-specific, corresponding to the occluded location in the visual field. However, the activity did not encode enough information about object identity to discriminate between different kinds of occluded objects (circles vs. stars) using MVPA. In contrast, object identity could be decoded in spatially-specific subregions of higher-order, topographically organized areas such as ventral, lateral, and temporal occipital areas (VO, LO, and TO) as well as the functionally defined LOC and hMT+. These results suggest that early visual cortex may represent the dynamically occluded object’s position or motion path, while later visual areas represent object-specific information. PMID:27663987

Iridium clusters in KLTL zeolite: Synthesis, structural characterization, and catalysis of toluene hydrogenation and n-hexane dehydrocyclization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, A.; Jentoft, R.E.; Gates, B.C.

Iridium clusters incorporating about six atoms each, on average, were prepared in KLTL zeolite by decarbonylation (in H{sub 2} at 400{degrees}C) of iridium carbonyl clusters formed by treatment of adsorbed [Ir(CO){sub 2}(acac)] in CO at 1 atm and 175{degrees}C. The supported species were characterized by infrared and extended X-ray absorption fine structure (EXAFS) spectroscopies. The iridium carbonyls formed from [Ir(CO){sub 2}(acac)] were predominantly [HIr{sub 4}(CO){sub 11}]{sup -} with a small amount of [Ir(CO){sub 4}]{sup -}. The synthesis chemistry of iridium carbonyls in the basic KLTL zeolite parallels that in basic solutions. Shifts of the {nu}{sub CO} bands of the iridiummore » carbonyl clusters relative to those of the same clusters in solution indicate strong interactions between the clusters and zeolite cations. The decarbonylated sample, approximated as Ir{sub 6}/KLTL zeolite, is catalytically active for toluene hydrogenation at 60-100{degrees}C, with the activity being approximately the same as those of Ir{sub 4} and Ir{sub 6} clusters supported on metal oxides, but an order of magnitude less than that of a conventional supported iridium catalyst consisting of aggregates of about 50 atoms each, on average. The catalyst is also active for conversion of n-hexane + H{sub 2} at 340-420{degrees}C, but the selectivity for aromatization is low and that for hydrogenolysis is high, consistent with earlier results for conventionally prepared (salt-derived) iridium clusters of about the same size supported in KLTL zeolite. The zeolite-supported iridium clusters are the first prepared from both salt and organometallic precursors; the results indicate that the organometallic and conventional preparation routes lead to supported iridium clusters having similar structures and catalytic properties. 59 refs., 6 figs., 7 tabs.« less

Hydraulic conductivity of compacted zeolites.

PubMed

Oren, A Hakan; Ozdamar, Tuğçe

2013-06-01

Hydraulic conductivities of compacted zeolites were investigated as a function of compaction water content and zeolite particle size. Initially, the compaction characteristics of zeolites were determined. The compaction test results showed that maximum dry unit weight (γ(dmax)) of fine zeolite was greater than that of granular zeolites. The γ(dmax) of compacted zeolites was between 1.01 and 1.17 Mg m(-3) and optimum water content (w(opt)) was between 38% and 53%. Regardless of zeolite particle size, compacted zeolites had low γ(dmax) and high w(opt) when compared with compacted natural soils. Then, hydraulic conductivity tests were run on compacted zeolites. The hydraulic conductivity values were within the range of 2.0 × 10(-3) cm s(-1) to 1.1 × 10(-7) cm s(-1). Hydraulic conductivity of all compacted zeolites decreased almost 50 times as the water content increased. It is noteworthy that hydraulic conductivity of compacted zeolite was strongly dependent on the zeolite particle size. The hydraulic conductivity decreased almost three orders of magnitude up to 39% fine content; then, it remained almost unchanged beyond 39%. Only one report was found in the literature on the hydraulic conductivity of compacted zeolite, which is in agreement with the findings of this study.

I. Synthesis, characterization, and base catalysis of novel zeolite supported super-basic materials II. Oxidative dehydrogenation of ethane over reduced heteropolyanion catalysts

NASA Astrophysics Data System (ADS)

Galownia, Jonathan M.

This thesis is composed of two separate and unrelated projects. The first part of this thesis outlines an investigation into the synthesis and characterization of a novel zeolite supported super-base capable of carbon-carbon olefin addition to alkyl aromatics. A zeolite supported basic material capable of such reactions would benefit many fine chemical syntheses, as well as vastly improve the economics associated with production of the high performance thermoplastic polyester polyethylene naphthalate. The thermal decomposition of alkali---metal azides impregnated in zeolite X is investigated as a novel route to the synthesis of a zeolite supported super-base. Impregnation of the alkali---metal azide precursor is shown to result in azide species occluded within the pores of the zeolite support by using high speed, solid-state 23Na MAS and 2D MQMAS NMR, FTIR, and TGA characterization methods. Addition of alkali---metal azides to the zeolite results in redistribution of the extra-lattice cations in the zeolite framework. Thermal decomposition of impregnated azide species produces further cation redistribution, but no neutral metallic clusters are detected by high speed, solid-state 23Na MAS NMR following thermal activation of the materials. Instead, it is possible that inactive ionic clusters are formed. The thermally activated materials do not promote base catalysis for the isomerization of 1-butene, the ethylation of toluene and o-xylene, and the alkenylation of o-xylene with 1,3-butadiene to produce 5-ortho-tolyl-pent-2-ene (5-OTP). The lack of catalytic activity in the materials is attributed to failure of the materials to form neutral metallic clusters during thermal treatment, possibly due to preferential formation of NMR silent ionic clusters. The formation of neutral metallic clusters is found to be insensitive to synthesis technique and activation procedure. It is concluded that the impregnation of alkali---metal azides in zeolite X does not provide a

Tailored zeolites for the removal of metal oxyanions: overcoming intrinsic limitations of zeolites.

PubMed

Figueiredo, Hugo; Quintelas, Cristina

2014-06-15

This review aims to present a global view of the efforts conducted to convert zeolites into efficient supports for the removal of heavy metal oxyanions. Despite lacking affinity for these species, due to inherent charge repulsion between zeolite framework and anionic species, zeolites have still received considerable attention from the scientific community, since their versatility allowed tailoring them to answer specific requirements. Different processes for the removal and recovery of toxic metals based on zeolites have been presented. These processes resort to modification of the zeolite surface to allow direct adsorption of oxyanions, or by combination with reducing agents for oxyanions that allow ion-exchange with the converted species by the zeolite itself. In order to testify zeolite versatility, as well as covering the wide array of physicochemical constraints that oxyanions offer, chromium and arsenic oxyanions were selected as model compounds for a review of treatment/remediation strategies, based on zeolite modification. Copyright © 2014 Elsevier B.V. All rights reserved.

Zeolites

NASA Technical Reports Server (NTRS)

1992-01-01

Zeolites are crystalline aluminosilicates that have complex framework structures. However, there are several features of zeolite crystals that make unequivocal structure determinations difficult. The acquisition of reliable structural information on zeolites is greatly facilitated by the availability of high-quality specimens. For structure determinations by conventional diffraction techniques, large single-crystal specimens are essential. Alternatively, structural determinations by powder profile refinement methods relax the constraints on crystal size, but still require materials with a high degree of crystalline perfection. Studies conducted at CAMMP (Center for Advanced Microgravity Materials Processing) have demonstrated that microgravity processing can produce larger crystal sizes and fewer structural defects relative to terrestrial crystal growth. Principal Investigator: Dr. Albert Sacco

Transcatheter closure of ventricular septal defect with Occlutech Duct Occluder.

PubMed

Atik-Ugan, Sezen; Saltik, Irfan Levent

2018-04-01

Patent ductus arteriosus occluders are used for transcatheter closure of ventricular septal defects, as well as for closure of patent ductus arteriosus. The Occlutech Duct Occluder is a newly introduced device for transcatheter closure of patent ductus arteriosus. Here, we present a case in which the Occlutech Duct Occluder was successfully used on a patient for the closure of a perimembraneous ventricular septal defect.

Abu Zenima synthetic zeolite for removing iron and manganese from Assiut governorate groundwater, Egypt

NASA Astrophysics Data System (ADS)

Farrag, Abd El Hay Ali; Abdel Moghny, Th.; Mohamed, Atef Mohamed Gad; Saleem, Saleem Sayed; Fathy, Mahmoud

2017-10-01

Groundwater in Upper Egypt especially in Assiut Governorate is considered the second source of fresh water and used for drinking, agriculture, domestic and industrial purposes. Unfortunately, it is characterized by high concentrations of iron and manganese ions. The study aimed at synthesizing zeolite-4A from kaolinite for removing the excess iron and manganese ions from Assiut Governorate groundwater wells. Therefor, the kaolinite was hydrothermally treated through the metakaolinization and zeolitization processes to produce crystalline zeolite-4A. The chemical composition of crystalline zeolite-4A and its morphology were then characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Then the column experiments were conducted to study the performance of crystalline salt-4A as ion exchange and investigate their operating parameters and regeneration conditions. Thomas and Yoon-Nelson models were applied to predict adsorption capacity and the time required for 50 % breakthrough curves. The effects of initial concentrations of 600 and 1000 mg L-1 for Fe2+ and Mn2+, feed flow rate of 10-30 ml/min, and height range of 0.4-1.5 cm on the breakthrough behavior of the adsorption system were determined. The obtained results indicated that the synthesized zeolite-A4 can remove iron and manganese ions from groundwater to the permissible limit according to the standards drinking water law.

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...

Treatment Study Plan for Nitrate Salt Waste Remediation Revision 1.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juarez, Catherine L.; Funk, David John; Vigil-Holterman, Luciana R.

2016-03-07

The two stabilization treatment methods that are to be examined for their effectiveness in the treatment of both the unremediated and remediated nitrate salt wastes include (1) the addition of zeolite and (2) cementation. Zeolite addition is proposed based on the results of several studies and analyses that specifically examined the effectiveness of this process for deactivating nitrate salts. Cementation is also being assessed because of its prevalence as an immobilization method used for similar wastes at numerous facilities around the DOE complex, including at Los Alamos. The results of this Treatment Study Plan will be used to provide themore » basis for a Resource Conservation and Recovery Act (RCRA) permit modification request of the LANL Hazardous Waste Facility Permit for approval by the New Mexico Environment Department-Hazardous Waste Bureau (NMED-HWB) of the proposed treatment process and the associated facilities.« less

Removal of paraquat solution onto zeolite material

NASA Astrophysics Data System (ADS)

Sirival, Rujikarn; Patdhanagul, Nopbhasinthu; Preecharram, Sutthidech; Photharin, Somkuan

2018-04-01

The purpose of this research was to study the adsorption of paraquat herbicides onto zeolite Y materials by the batch method. Three adsorbents material: Zeolite-3, Zeolite-10, and Zeolite-100 were Si/Al ratio at 3.58, 8.57 and 154.37, respectively. The factors for adsorption of paraquat as follows, adsorption time, initial concentrations of paraquat, pH and adsorption isotherm were investigated. The results showed that zeolite-10 had higher adsorption capacity than zeolite-3 and zeolite-100. The appropriate conditions for adsorption were 24 h., Zeolite 0.1 g., Initial paraquat concentration 100 ppm at pH 6. The adsorption isotherm was found to correspond with Langmuir Isotherm and the maximum paraquat adsorption is 26.38 mg/g for zeolite-10, 21.41 mg/g and 9.60 mg/g for zeolite-3 and zeolite-100, respectively. The characterization of zeolite material with XRD, XRF and BET. Furthermore, the zeolite materials applied to remove other organic and inorganic wastewater.

Rapid synthesis of beta zeolites

DOEpatents

Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng

2015-08-18

The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

Hemolysis induced by PMIVSD occluder.

PubMed

Rao, D Sheshagiri; Barik, Ramachandra; Siva Prasad, Akula

2016-09-01

Hemolysis related to occluder, prosthetic valve, and prosthetic ring used for mitral valve annuloplasty are not very unusual. However, hemolysis related to transcathetor closure of post-myocardial infarction ventricular septal defect (PMIVSD) is infrequent. A close follow-up for spontaneous resolution with or without blood transfusion has been reported in a few cases. Occasionally, surgical retrieval is unavoidable or lifelong blood transfusion is required if surgery cannot be done because of higher risk. In this illustration, we have showed a close follow-up of a case of hemolysis induced by atrial septal occluder used for VSD closure after myocardial infarction. Despite successful device closure of PMIVSD which is difficult, a close watch is needed for complications like residual leak, device embolization, and hemolysis. Copyright © 2016 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

Synthesis of Engineered Zeolitic Materials: From Classical Zeolites to Hierarchical Core-Shell Materials.

PubMed

Masoumifard, Nima; Guillet-Nicolas, Rémy; Kleitz, Freddy

2018-04-01

The term "engineered zeolitic materials" refers to a class of materials with a rationally designed pore system and active-sites distribution. They are primarily made of crystalline microporous zeolites as the main building blocks, which can be accompanied by other secondary components to form composite materials. These materials are of potential importance in many industrial fields like catalysis or selective adsorption. Herein, critical aspects related to the synthesis and modification of such materials are discussed. The first section provides a short introduction on classical zeolite structures and properties, and their conventional synthesis methods. Then, the motivating rationale behind the growing demand for structural alteration of these zeolitic materials is discussed, with an emphasis on the ongoing struggles regarding mass-transfer issues. The state-of-the-art techniques that are currently available for overcoming these hurdles are reviewed. Following this, the focus is set on core-shell composites as one of the promising pathways toward the creation of a new generation of highly versatile and efficient engineered zeolitic substances. The synthesis approaches developed thus far to make zeolitic core-shell materials and their analogues, yolk-shell, and hollow materials, are also examined and summarized. Finally, the last section concisely reviews the performance of novel core-shell, yolk-shell, and hollow zeolitic materials for some important industrial applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

NASA Astrophysics Data System (ADS)

Gianni, Areti; Zacharias, Ierotheos

2015-04-01

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

Design and characterization of chitosan/zeolite composite films--Effect of zeolite type and zeolite dose on the film properties.

PubMed

Barbosa, Gustavo P; Debone, Henrique S; Severino, Patrícia; Souto, Eliana B; da Silva, Classius F

2016-03-01

Chitosan films can be used as wound dressings for the treatment of chronic wounds and severe burns. The antimicrobial properties of these films may be enhanced by the addition of silver. Despite the antimicrobial activity of silver, several studies have reported the cytotoxicity as a factor limiting its biomedical applications. This problem may, however, be circumvented by the provision of sustained release of silver. Silver zeolites can be used as drug delivery platforms to extend the release of silver. The objective of this study was to evaluate the addition of clinoptilolite and A-type zeolites in chitosan films. Sodium zeolites were initially subjected to ion-exchange in a batch reactor. Films were prepared by casting technique using a 2% w/w chitosan solution and two zeolite doses (0.1 or 0.2% w/w). Films were characterized by thermal analysis, color analysis, scanning electron microscopy, X-ray diffraction, and water vapor permeation. The results showed that films present potential for application as dressing. The water vapor permeability is one of the main properties in wound dressings, the best results were obtained for A-type zeolite/chitosan films, which presented a brief reduction of this property in relation to zeolite-free chitosan film. On the other hand, the films containing clinoptilolite showed lower water vapor permeation, which may be also explained by the best distribution of the particles into the polymer which also promoted greater thermal resistance.

Zeolite crystal growth in space

NASA Technical Reports Server (NTRS)

Sacco, Albert, Jr.; Thompson, Robert W.; Dixon, Anthony G.

1991-01-01

The growth of large, uniform zeolite crystals in high yield in space can have a major impact on the chemical process industry. Large zeolite crystals will be used to improve basic understanding of adsorption and catalytic mechanisms, and to make zeolite membranes. To grow large zeolites in microgravity, it is necessary to control the nucleation event and fluid motion, and to enhance nutrient transfer. Data is presented that suggests nucleation can be controlled using chemical compounds (e.g., Triethanolamine, for zeolite A), while not adversely effecting growth rate. A three-zone furnace has been designed to perform multiple syntheses concurrently. The operating range of the furnace is 295 K to 473 K. Teflon-lined autoclaves (10 ml liquid volume) have been designed to minimize contamination, reduce wall nucleation, and control mixing of pre-gel solutions on orbit. Zeolite synthesis experiments will be performed on USML-1 in 1992.

DeNOx Abatement over Sonically Prepared Iron-Substituted Y, USY and MFI Zeolite Catalysts in Lean Exhaust Gas Conditions

PubMed Central

Stachurska, Patrycja; Kuterasiński, Łukasz; Dziedzicka, Anna; Górecka, Sylwia; Chmielarz, Lucjan; Łojewska, Joanna; Sitarz, Maciej

2018-01-01

Iron-substituted MFI, Y and USY zeolites prepared by two preparation routes—classical ion exchange and the ultrasound modified ion-exchange method—were characterised by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet (UV)/visible diffuse reflectance spectroscopy (UV/Vis DRS). Ultrasound irradiation, a new technique for the preparation of the metal salt suspension before incorporation to the zeolite structure, was employed. An experimental study of selective catalytic reduction (SCR) of NO with NH3 on both iron-substituted reference zeolite catalysts and those prepared through the application of ultrasound conducted during an ion-exchange process is presented. The prepared zeolite catalysts show high activity and selectivity in SCR deNOx abatement. The MFI-based iron catalysts, especially those prepared via the sonochemical method, revealed superior activity in the deNOx process, with almost 100% selectivity towards N2. The hydrothermal stability test confirmed high stability and activity of MFI-based catalysts in water-rich conditions during the deNOx reaction at 450 °C. PMID:29301370

Catalytic Fast Pyrolysis of Cellulose Using Nano Zeolite and Zeolite/Matrix Catalysts in a GC/Micro-Pyrolyzer.

PubMed

Lee, Kyong-Hwan

2016-05-01

Cellulose, as a model compound of biomass, was catalyzed over zeolite (HY,.HZSM-5) and zeolite/matrix (HY/Clay, HM/Clay) in a GC/micro-pyrolyzer at 500 degrees C, to produce the valuable products. The catalysts used were pure zeolite and zeolite/matrix including 20 wt% matrix content, which were prepared into different particle sizes (average size; 0.1 mm, 1.6 mm) to study the effect of the particle size of the catalyst for the distribution of product yields. Catalytic pyrolysis had much more volatile products as light components and less content of sugars than pyrolysis only. This phenomenon was strongly influenced by the particle size of the catalyst in catalytic fast pyrolysis. Also, in zeolite and zeolite/matrix catalysts the zeolite type gave the dominant impact on the distribution of product yields.

New antiaxillary odour deodorant made with antimicrobial Ag-zeolite (silver-exchanged zeolite).

PubMed

Nakane, T; Gomyo, H; Sasaki, I; Kimoto, Y; Hanzawa, N; Teshima, Y; Namba, T

2006-08-01

The causative substances for axillary osmidrosis, which are often found in apocrine sweat, are the decomposed/denatured products of short-chain fatty acid and other biological metabolite compounds produced by axillary-resident bacteria. Conventional underarm deodorants suppress the process of odour production mostly by the following mechanism: (1) suppression of perspiration, (2) reduction in numbers of resident bacteria, (3) deodorization and (4) masking. The most important and effective method to reduce odour is to suppress the growth of resident bacteria with antimicrobials, which have several drawbacks, especially in their safety aspect. To solve these problems, we focused on Ag-zeolite (silver-exchanged zeolite) that hold stable Ag, an inorganic bactericidal agent, in its structure, and therefore, poses less risk in safety. Its bactericidal effect on skin-resident bacteria was found to be excellent and comparable with that of triclosan, a most frequently used organic antimicrobial in this product category. The dose-response study of Ag-zeolite powder spray (0-40 w/w%) using 39 volunteers revealed that 5-40 w/w% Ag-zeolite could show a sufficient antimicrobial effect against skin-resident bacteria. The comparison study using 0.2 w/w% triclosan as the control and 10 w/w% Ag-zeolite indicated that: (1) one application of the powder spray containing 10 w/w% Ag-zeolite could show a sufficient antimicrobial effect against the resident bacteria and its effect continued for 24 h, (2) a powder spray containing 0.2 w/w% triclosan was unable to show a sufficient antimicrobial effect, and (3) no adverse event was observed. These studies show that Ag-zeolite has a superior antimicrobial ability that is rarely found in conventional antimicrobials used in deodorant products and a strong antiaxillary odour deodorant ability because of its long-lasting effect. During clinical study, patch tests with humans and other clinical studies of this product showed no adverse events

Zeolite A imidazolate frameworks

NASA Astrophysics Data System (ADS)

Hayashi, Hideki; Côté, Adrien P.; Furukawa, Hiroyasu; O'Keeffe, Michael; Yaghi, Omar M.

2007-07-01

Faujasite (FAU) and zeolite A (LTA) are technologically important porous zeolites (aluminosilicates) because of their extensive use in petroleum cracking and water softening. Introducing organic units and transition metals into the backbone of these types of zeolite allows us to expand their pore structures, enhance their functionality and access new applications. The invention of metal-organic frameworks and zeolitic imidazolate frameworks (ZIFs) has provided materials based on simple zeolite structures where only one type of cage is present. However, so far, no metal-organic analogues based on FAU or LTA topologies exist owing to the difficulty imposed by the presence of two types of large cage (super- and β-cages for FAU, α- and β-cages for LTA). Here, we have identified a strategy to produce an LTA imidazolate framework in which both the link geometry and link-link interactions play a decisive structure-directing role. We describe the synthesis and crystal structures of three porous ZIFs that are expanded analogues of zeolite A; their cage walls are functionalized, and their metal ions can be changed without changing the underlying LTA topology. Hydrogen, methane, carbon dioxide and argon gas adsorption isotherms are reported and the selectivity of this material for carbon dioxide over methane is demonstrated.

Zeolite A imidazolate frameworks.

PubMed

Hayashi, Hideki; Côté, Adrien P; Furukawa, Hiroyasu; O'Keeffe, Michael; Yaghi, Omar M

2007-07-01

Faujasite (FAU) and zeolite A (LTA) are technologically important porous zeolites (aluminosilicates) because of their extensive use in petroleum cracking and water softening. Introducing organic units and transition metals into the backbone of these types of zeolite allows us to expand their pore structures, enhance their functionality and access new applications. The invention of metal-organic frameworks and zeolitic imidazolate frameworks (ZIFs) has provided materials based on simple zeolite structures where only one type of cage is present. However, so far, no metal-organic analogues based on FAU or LTA topologies exist owing to the difficulty imposed by the presence of two types of large cage (super- and beta-cages for FAU, alpha- and beta-cages for LTA). Here, we have identified a strategy to produce an LTA imidazolate framework in which both the link geometry and link-link interactions play a decisive structure-directing role. We describe the synthesis and crystal structures of three porous ZIFs that are expanded analogues of zeolite A; their cage walls are functionalized, and their metal ions can be changed without changing the underlying LTA topology. Hydrogen, methane, carbon dioxide and argon gas adsorption isotherms are reported and the selectivity of this material for carbon dioxide over methane is demonstrated.

Comparison of factors associated with occludable angle between american Caucasians and ethnic Chinese.

PubMed

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-11-21

To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40-80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese.

Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite.

PubMed

Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

2016-02-01

The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550°C, 5h) and this material has excellent performance as an antibacterial agent after silver ions loading. Copyright © 2015 Elsevier B.V. All rights reserved.

Photochemical charge separation in zeolites: Electron transfer dynamics, nanocrystals and zeolitic membranes. Final technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dutta, Prabir K.

2001-09-30

Aluminosilicate zeolites provide an excellent host for photochemical charge separation. Because of the constraints provided by the zeolite, the back electron transfer from the reduced acceptor to the oxidized sensitizer is slowed down. This provides the opportunity to separate the charge and use it in a subsequent reaction for water oxidation and reduction. Zeolite-based ruthenium oxide catalysts have been found to be efficient for the water splitting process. This project has demonstrated the usefulness of zeolite hosts for photolytic splitting of water.

Vascular occlusion with a balloon-expandable stent occluder.

PubMed

Moss, J G; Laborde, J C; Clem, M C; Rivera, F J; Encarnacion, C E; Meyer, K B; Palmaz, J C

1994-05-01

To evaluate the effectiveness of a new vascular occlusion device. The device was created by coating a balloon-expandable stent with a silicone sleeve that tapers to a blind-ended nozzle at its leading end. Once crimp-mounted on an angioplasty balloon catheter, the device is introduced over a guide wire through a small end hole in the nozzle. The device was tested for stability and occlusive ability. No migration was measured over a pulsatile pulse range of 50-300 mm Hg, and mean flow rate in the occluded vessel was reduced from 443 mL/min +/- 99 (standard deviation) to 1.9 mL/min +/- 2.7. Subsequently, 12 arteries were occluded in three dogs, and immediate vascular occlusion was achieved in all vessels. An arteriovenous fistula was created in another six dogs and was successfully occluded with the device. Follow-up arteriography at 3 months demonstrated persistent occlusion with no migration of the device. This new occlusive device offers immediate vascular occlusion with excellent stability.

Closure of large patent ductus arteriosus using the Amplatzer Septal Occluder.

PubMed

García-Montes, José A; Camacho-Castro, Anahí; Sandoval-Jones, Juan P; Buendía-Hernández, Alfonso; Calderón-Colmenero, Juan; Patiño-Bahena, Emilia; Zabal, Carlos

2015-03-01

Percutaneous closure of patent ductus arteriosus has become the treatment of choice in many centres. In patients with large ducts and pulmonary hypertension, transcatheter closure has been achieved with success using the Amplatzer Duct Occluder or even the Amplatzer Muscular Ventricular Septal Defect Occluder. We present a series of 17 patients with large and hypertensive ductus arteriosus who were treated with an Amplatzer Septal Occluder. The group had 11 female patients (64.7%) and a mean age of 18.6±12.1 years. The haemodynamic and anatomical data are as follows: pulmonary artery systolic pressure 71.3±31.8 mmHg, pulmonary to systemic flow ratio 3.14±1.36, ductal diameter at the pulmonary end 12.5±3.8 mm, and at the aortic end 20.2±7.7 mm; 14 cases (82.3%) had type A ducts. In 11 patients, we began the procedure using a different device - six with duct occluder and five with ventricular septal occluder - and it was changed because of device embolisation in six (35.3%). All septal occluders were delivered successfully. Residual shunt was moderate in six patients (35.3%), mild in eight (47%), trivial in two (11.8%), and no shunt in one (5.9%). Pulmonary systolic pressure decreased to 48.9±10.8 mmHg after occlusion (p=0.0015). Follow-up in 15 patients (88.2%) for 28.4±14.4 months showed complete closure in all cases but one, and continuous decrease of the pulmonary systolic pressure to 31.4±10.5 mmHg. No complications at follow-up have been reported. The Amplatzer Septal Occluder is a good alternative to percutaneously treat large and hypertensive ductus arteriosus.

Characterization of Zeolite in Zeolite-Geopolymer Hybrid Bulk Materials Derived from Kaolinitic Clays

PubMed Central

Takeda, Hayami; Hashimoto, Shinobu; Yokoyama, Hiroaki; Honda, Sawao; Iwamoto, Yuji

2013-01-01

Zeolite-geopolymer hybrid materials have been formed when kaolin was used as a starting material. Their characteristics are of interest because they can have a wide pore size distribution with micro- and meso-pores due to the zeolite and geopolymer, respectively. In this study, Zeolite-geopolymer hybrid bulk materials were fabricated using four kinds of kaolinitic clays (a halloysite and three kinds of kaolinite). The kaolinitic clays were first calcined at 700 °C for 3 h to transform into the amorphous aluminosilicate phases. Alkali-activation treatment of the metakaolin yielded bulk materials with different amounts and types of zeolite and different compressive strength. This study investigated the effects of the initial kaolinitic clays on the amount and types of zeolite in the resultant geopolymers as well as the strength of the bulk materials. The kaolinitic clays and their metakaolin were characterized by XRD analysis, chemical composition, crystallite size, 29Si and 27Al MAS NMR analysis, and specific surface area measurements. The correlation between the amount of zeolite formed and the compressive strength of the resultant hybrid bulk materials, previously reported by other researchers was not positively observed. In the studied systems, the effects of Si/Al and crystalline size were observed. When the atomic ratio of Si/Al in the starting kaolinitic clays increased, the compressive strength of the hybrid bulk materials increased. The crystallite size of the zeolite in the hybrid bulk materials increased with decreasing compressive strength of the hybrid bulk materials. PMID:28809241

Properties and applications of zeolites.

PubMed

Rhodes, Christopher J

2010-01-01

Zeolites are aluminosilicate solids bearing a negatively charged honeycomb framework of micropores into which molecules may be adsorbed for environmental decontamination, and to catalyse chemical reactions. They are central to green-chemistry since the necessity for organic solvents is minimised. Proton-exchanged (H) zeolites are extensively employed in the petrochemical industry for cracking crude oil fractions into fuels and chemical feedstocks for other industrial processes. Due to their ability to perform cation-exchange, in which the cations that are originally present to counterbalance the framework negative charge may be exchanged out of the zeolite by cations present in aqueous solution, zeolites are useful as industrial water-softeners, in the removal of radioactive Cs+ and Sr2+ cations from liquid nuclear waste and in the removal of toxic heavy metal cations from groundwaters and run-off waters. Surfactant-modified zeolites (SMZ) find particular application in the co-removal of both toxic anions and organic pollutants. Toxic anions such as arsenite, arsenate, chromate, cyanide and radioactive iodide can also be removed by adsorption into zeolites that have been previously loaded with co-precipitating metal cations such as Ag+ and Pb2+ which form practically insoluble complexes that are contained within the zeolite matrix.

Comparison of Factors Associated With Occludable Angle Between American Caucasians and Ethnic Chinese

PubMed Central

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-01-01

Purpose. To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. Methods. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40–80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. Results. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Conclusions. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese. PMID:24168992

Design and fabrication of zeolite macro- and micromembranes

NASA Astrophysics Data System (ADS)

Chau, Lik Hang Joseph

2001-07-01

The chemical nature of the support surface influences zeolite nucleation, crystal growth and elm adhesion. It had been demonstrated that chemical modification of support surface can significantly alter the zeolite film and has a good potential for large-scale applications for zeolite membrane production. The incorporation of titanium and vanadium metal ions into the structural framework of MFI zeolite imparts the material with catalytic properties. The effects of silica and metal (i.e., Ti and V) content, template concentration and temperature on the zeolite membrane growth and morphology were investigated. Single-gas permeation experiments were conducted for noble gases (He and Ar), inorganic gases (H2, N2, SF6) and hydrocarbons (methane, n-C4, i-C4) to determine the separation performance of these membranes. Using a new fabrication method based on microelectronic fabrication and zeolite thin film technologies, complex microchannel geometry and network (<5 mum), as well as zeolite arrays (<10 mum) were successfully fabricated onto highly orientated supported zeolite films. The zeolite micropatterns were stable even after repeated thermal cycling between 303 K and 873 K for prolonged periods of time. This work also demonstrates that zeolites (i.e., Sil-1, ZSM-5 and TS-1) can be employed as catalyst, membrane or structural materials in miniature chemical devices. Traditional semiconductor fabrication technology was employed in micromachining the device architecture. Four strategies for the manufacture of zeolite catalytic microreactors were discussed: zeolite powder coating, uniform zeolite film growth, localized zeolite growth, and etching of zeolite-silicon composite film growth inhibitors. Silicalite-1 was also prepared as free-standing membrane for zeolite membrane microseparators.

Phonation Threshold Pressure Measurement with a Semi-Occluded Vocal Tract

ERIC Educational Resources Information Center

Titze, Ingo R.

2009-01-01

Purpose: The purpose of this article was to determine if a semi-occluded vocal tract could be used to measure phonation threshold pressure. This is in contrast to the shutter technique, where an alternation between a fully occluded tract and an unoccluded tract is used. Method: Five male and 5 female volunteers phonated through a thin straw held…

Recent development of transcatheter closure of atrial septal defect and patent foramen ovale with occluders.

PubMed

Tang, Baiyu; Su, Feng; Sun, Xiangke; Wu, Qin; Xing, Quansheng; Li, Suming

2018-01-01

Atrial septal defect (ASD) and patent foramen ovale (PFO) are common clinical congenital heart defects. As an effective method for the treatment of ASD and PFO, transcatheter closure with occluders presents many advantages, including safety, ease of operation, minimal invasiveness, and reduced complications. This contribution reviews the various types of occluders currently used in clinical applications and under development, including non degradable occluders, partially degradable occluders, and totally degradable occluders. A number of case studies are described in detail. Comparison is made on the treatment outcomes using different occulders. Future development of transcatheter closure is discussed, in particular the use of totally degradable occluders. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 433-443, 2018. © 2016 Wiley Periodicals, Inc.

Oxygen and hydrogen isotope geochemistry of zeolites

NASA Technical Reports Server (NTRS)

Karlsson, Haraldur R.; Clayton, Robert N.

1990-01-01

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

Zeolites: Exploring Molecular Channels

ScienceCinema

Arslan, Ilke; Derewinski, Mirek

2018-05-16

Synthetic zeolites contain microscopic channels, sort of like a sponge. They have many uses, such as helping laundry detergent lather, absorbing liquid in kitty litter, and as catalysts to produce fuel. Of the hundreds of types of zeolites, only about 15 are used for catalysis. PNNL catalysis scientists Ilke Arslan and Mirek Derewinksi are studying these zeolites to understand what make them special. By exploring the mystery of these microscopic channels, their fundamental findings will help design better catalysts for applications such as biofuel production.

Diagram of Zeolite Crystals

NASA Technical Reports Server (NTRS)

2003-01-01

The Center for Advanced Microgravity Materials Processing (CAMMP) in Cambridge, MA, a NASA-sponsored Commercial Space Center, is working to improve zeolite materials for storing hydrogen fuel. CAMMP is also applying zeolites to detergents, optical cables, gas and vapor detection for environmental monitoring and control, and chemical production techniques that significantly reduce by-products that are hazardous to the environment. Depicted here is one of the many here complex geometric shapes which make them highly absorbent. Zeolite experiments have also been conducted aboard the International Space Station

Zeolites: Exploring Molecular Channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arslan, Ilke; Derewinski, Mirek

2015-05-22

Synthetic zeolites contain microscopic channels, sort of like a sponge. They have many uses, such as helping laundry detergent lather, absorbing liquid in kitty litter, and as catalysts to produce fuel. Of the hundreds of types of zeolites, only about 15 are used for catalysis. PNNL catalysis scientists Ilke Arslan and Mirek Derewinksi are studying these zeolites to understand what make them special. By exploring the mystery of these microscopic channels, their fundamental findings will help design better catalysts for applications such as biofuel production.

Pd/Cu-Oxide Nanoconjugate at Zeolite-Y Crystallite Crafting the Mesoporous Channels for Selective Oxidation of Benzyl-Alcohols.

PubMed

Sharma, Mukesh; Das, Biraj; Sharma, Mitu; Deka, Biplab K; Park, Young-Bin; Bhargava, Suresh K; Bania, Kusum K

2017-10-11

Solid-state grinding of palladium and copper salts allowed the growth of palladium/copper oxide interface at the zeolite-Y surface. The hybrid nanostructured material was used as reusable heterogeneous catalyst for selective oxidation of various benzyl alcohols. The large surface area provided by the zeolite-Y matrix highly influenced the catalytic activity, as well as the recyclability of the synthesized catalyst. Impregnation of PdO-CuO nanoparticles on zeolite crystallite leads to the generation of mesoporous channel that probably prevented the leaching of the metal-oxide nanoparticles and endorsed high mass transfer. Formation of mesoporous channel at the external surface of zeolite-Y was evident from transmission electron microscopy and surface area analysis. PdO-CuO nanoparticles were found to be within the range of 2-5 nm. The surface area of PdO-CuO-Y catalyst was found to be much lower than parent zeolite-Y. The decrease in surface area as well as the presence of hysteresis loop in the N 2 -adsoprtion isotherm further suggested successful encapsulation of PdO-CuO nanoparticles via the mesoporous channel formation. The high positive shifting in binding energy in both Pd and Cu was attributed to the influence of zeolite-Y framework on lattice contraction of metal oxides via confinement effect. PdO-CuO-Y catalyst was found to oxidize benzyl alcohol with 99% selectivity. On subjecting to microwave irradiation the same oxidation reaction was found to occur at ambient condition giving same conversion and selectivity.

Micromechanical processes in consolidated granular salt

DOE PAGES

Mills, Melissa Marie; Stormont, John C.; Bauer, Stephen J.

2018-03-27

Here, granular salt is likely to be used as backfill material and a seal system component within geologic salt formations serving as a repository for long-term isolation of nuclear waste. Pressure from closure of the surrounding salt formation will promote consolidation of granular salt, eventually resulting in properties comparable to native salt. Understanding dependence of consolidation processes on stress state, moisture availability, temperature, and time is important for demonstrating sealing functions and long-term repository performance. This study characterizes laboratory-consolidated granular salt by means of microstructural observations. Granular salt material from mining operations was obtained from the bedded Salado Formation hostingmore » the Waste Isolation Pilot Plant and the Avery Island salt dome. Laboratory test conditions included hydrostatic consolidation of jacketed granular salt with varying conditions of confining isochoric stress to 38 MPa, temperature to 250 °C, moisture additions of 1% by weight, time duration, and vented and non-vented states. Resultant porosities ranged between 1% and 22%. Optical and scanning electron microscopic techniques were used to ascertain consolidation mechanisms. From these investigations, samples with 1% added moisture or unvented during consolidation, exhibit clear pressure solution processes with tightly cohered grain boundaries and occluded fluid pores. Samples with only natural moisture content consolidated by a combination of brittle, cataclastic, and crystal plastic deformation. Recrystallization at 250 °C irrespective of moisture conditions was also observed. The range and variability of conditions applied in this study, combined with the techniques used to display microstructural features, are unique, and provide insight into an important area of governing deformation mechanism(s) occurring within salt repository applications.« less

Micromechanical processes in consolidated granular salt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mills, Melissa Marie; Stormont, John C.; Bauer, Stephen J.

Here, granular salt is likely to be used as backfill material and a seal system component within geologic salt formations serving as a repository for long-term isolation of nuclear waste. Pressure from closure of the surrounding salt formation will promote consolidation of granular salt, eventually resulting in properties comparable to native salt. Understanding dependence of consolidation processes on stress state, moisture availability, temperature, and time is important for demonstrating sealing functions and long-term repository performance. This study characterizes laboratory-consolidated granular salt by means of microstructural observations. Granular salt material from mining operations was obtained from the bedded Salado Formation hostingmore » the Waste Isolation Pilot Plant and the Avery Island salt dome. Laboratory test conditions included hydrostatic consolidation of jacketed granular salt with varying conditions of confining isochoric stress to 38 MPa, temperature to 250 °C, moisture additions of 1% by weight, time duration, and vented and non-vented states. Resultant porosities ranged between 1% and 22%. Optical and scanning electron microscopic techniques were used to ascertain consolidation mechanisms. From these investigations, samples with 1% added moisture or unvented during consolidation, exhibit clear pressure solution processes with tightly cohered grain boundaries and occluded fluid pores. Samples with only natural moisture content consolidated by a combination of brittle, cataclastic, and crystal plastic deformation. Recrystallization at 250 °C irrespective of moisture conditions was also observed. The range and variability of conditions applied in this study, combined with the techniques used to display microstructural features, are unique, and provide insight into an important area of governing deformation mechanism(s) occurring within salt repository applications.« less

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

PubMed

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

2014-06-15

In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity. Copyright © 2014 Elsevier B.V. All rights reserved.

Rapid screening of the antimicrobial efficacy of Ag zeolites.

PubMed

Tosheva, L; Belkhair, S; Gackowski, M; Malic, S; Al-Shanti, N; Verran, J

2017-09-01

A semi-quantitative screening method was used to compare the killing efficacy of Ag zeolites against bacteria and yeast as a function of the zeolite type, crystal size and concentration. The method, which substantially reduced labor, consumables and waste and provided an excellent preliminary screen, was further validated by quantitative plate count experiments. Two pairs of zeolite X and zeolite beta with different sizes (ca. 200nm and 2μm for zeolite X and ca. 250 and 500nm for zeolite beta) were tested against Escherichia coli (E. coli) and Candida albicans (C. albicans) at concentrations in the range 0.05-0.5mgml -1 . Reduction of the zeolite crystal size resulted in a decrease in the killing efficacy against both microorganisms. The semi-quantitative tests allowed convenient optimization of the zeolite concentrations to achieve targeted killing times. Zeolite beta samples showed higher activity compared to zeolite X despite their lower Ag content, which was attributed to the higher concentration of silver released from zeolite beta samples. Cytotoxicity measurements using peripheral blood mononuclear cells (PBMCs) indicated that Ag zeolite X was more toxic than Ag zeolite beta. However, the trends for the dependence of cytotoxicity on zeolite crystal size at different zeolite concentrations were different for the two zeolites and no general conclusions about zeolite cytotoxicity could be drawn from these experiments. This result indicates a complex relationship, requiring the necessity for individual cytotoxicity measurements for all antimicrobial applications based on the use of zeolites. Copyright © 2017 Elsevier B.V. All rights reserved.

Energetics of sodium-calcium exchanged zeolite A.

PubMed

Sun, H; Wu, D; Guo, X; Shen, B; Navrotsky, A

2015-05-07

A series of calcium-exchanged zeolite A samples with different degrees of exchange were prepared. They were characterized by powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). High temperature oxide melt drop solution calorimetry measured the formation enthalpies of hydrated zeolites CaNa-A from constituent oxides. The water content is a linear function of the degree of exchange, ranging from 20.54% for Na-A to 23.77% for 97.9% CaNa-A. The enthalpies of formation (from oxides) at 25 °C are -74.50 ± 1.21 kJ mol(-1) TO2 for hydrated zeolite Na-A and -30.79 ± 1.64 kJ mol(-1) TO2 for hydrated zeolite 97.9% CaNa-A. Dehydration enthalpies obtained from differential scanning calorimetry are 32.0 kJ mol(-1) H2O for hydrated zeolite Na-A and 20.5 kJ mol(-1) H2O for hydrated zeolite 97.9% CaNa-A. Enthalpies of formation of Ca-exchanged zeolites A are less exothermic than for zeolite Na-A. A linear relationship between the formation enthalpy and the extent of calcium substitution was observed. The energetic effect of Ca-exchange on zeolite A is discussed with an emphasis on the complex interactions between the zeolite framework, cations, and water.

A Taxonomy of 3D Occluded Objects Recognition Techniques

NASA Astrophysics Data System (ADS)

Soleimanizadeh, Shiva; Mohamad, Dzulkifli; Saba, Tanzila; Al-ghamdi, Jarallah Saleh

2016-03-01

The overall performances of object recognition techniques under different condition (e.g., occlusion, viewpoint, and illumination) have been improved significantly in recent years. New applications and hardware are shifted towards digital photography, and digital media. This faces an increase in Internet usage requiring object recognition for certain applications; particularly occulded objects. However occlusion is still an issue unhandled, interlacing the relations between extracted feature points through image, research is going on to develop efficient techniques and easy to use algorithms that would help users to source images; this need to overcome problems and issues regarding occlusion. The aim of this research is to review recognition occluded objects algorithms and figure out their pros and cons to solve the occlusion problem features, which are extracted from occluded object to distinguish objects from other co-existing objects by determining the new techniques, which could differentiate the occluded fragment and sections inside an image.

Summary Report of Comprehensive Laboratory Testing to Establish the Effectiveness of Proposed Treatment Methods for Unremediated and Remediated Nitrate Salt Waste Streams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anast, Kurt Roy; Funk, David John; Hargis, Kenneth Marshall

The inadvertent creation of transuranic waste carrying hazardous waste codes D001 and D002 requires the treatment of the material to eliminate the hazardous characteristics and allow its eventual shipment and disposal at the Waste Isolation Pilot Plant (WIPP). This report documents the effectiveness of two treatment methods proposed to stabilize both the unremediated and remediated nitrate salt waste streams (UNS and RNS, respectively) at Los Alamos National Laboratory (LANL). The two technologies include the addition of zeolite (with and without the addition of water as a processing aid) and cementation. Surrogates were developed to evaluate both the solid and liquidmore » fractions expected from parent waste containers, and both the solid and liquid fractions were tested. Both technologies are shown to be effective at eliminating the characteristic of ignitability (D001), and the addition of zeolite was determined to be effective at eliminating corrosivity (D002), with the preferred option1 of adding zeolite currently planned for implementation at LANL’s Waste Characterization, Reduction, and Repackaging Facility (WCRRF). The course of this work verified the need to evaluate and demonstrate the effectiveness of the proposed remedy for debris material, if required. The evaluation determined that WypAlls, cheesecloth, and Celotex absorbed with saturated nitrate salt solutions exhibit the ignitability characteristic (all other expected debris is not classified as ignitable). Finally, liquid surrogates containing saturated nitrate salts did not exhibit the characteristic of ignitability in their pure form (those neutralized with Kolorsafe and mixed with sWheat did exhibit D001). Sensitivity testing and an analysis were conducted to evaluate the waste form for reactivity. Tests included subjecting surrogate material to mechanical impact, friction, electrostatic discharge and thermal insults. The testing confirmed that the waste does not exhibit the characteristic

Method to synthesize dense crystallized sodalite pellet for immobilizing halide salt radioactive waste

DOEpatents

Koyama, Tadafumi

1994-01-01

A method for immobilizing waste chloride salts containing radionuclides such as cesium and strontium and hazardous materials such as barium. A sodalite intermediate is prepared by mixing appropriate amounts of silica, alumina and sodium hydroxide with respect to sodalite and heating the mixture to form the sodalite intermediate and water. Heating is continued to drive off the water to form a water-free intermediate. The water-free intermediate is mixed with either waste salt or waste salt which has been contacted with zeolite to concentrate the radionuclides and hazardous material. The waste salt-intermediate mixture is then compacted and heated under conditions of heat and pressure to form sodalite with the waste salt, radionuclides and hazardous material trapped within the sodalite cage structure. This provides a final product having excellent leach resistant capabilities.

Method to synthesize dense crystallized sodalite pellet for immobilizing halide salt radioactive waste

DOEpatents

Koyama, Tadafumi.

1994-08-23

A method is described for immobilizing waste chloride salts containing radionuclides such as cesium and strontium and hazardous materials such as barium. A sodalite intermediate is prepared by mixing appropriate amounts of silica, alumina and sodium hydroxide with respect to sodalite and heating the mixture to form the sodalite intermediate and water. Heating is continued to drive off the water to form a water-free intermediate. The water-free intermediate is mixed with either waste salt or waste salt which has been contacted with zeolite to concentrate the radionuclides and hazardous material. The waste salt-intermediate mixture is then compacted and heated under conditions of heat and pressure to form sodalite with the waste salt, radionuclides and hazardous material trapped within the sodalite cage structure. This provides a final product having excellent leach resistant capabilities.

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.

Impacts of zeolite nanoparticles on substrate properties of thin film nanocomposite membranes for engineered osmosis

NASA Astrophysics Data System (ADS)

Salehi, Tahereh Mombeini; Peyravi, Majid; Jahanshahi, Mohsen; Lau, Woei-Jye; Rad, Ali Shokuhi

2018-04-01

In this work, microporous substrates modified by zeolite nanoparticles were prepared and used for composite membrane making with the aim of reducing internal concentration polarization (ICP) effect of membranes during engineered osmosis applications. Nanocomposite substrates were fabricated via phase inversion technique by embedding nanostructured zeolite (clinoptilolite) in the range of 0-0.6 wt% into matrix of polyethersulfone (PES) substrate. Of all the substrates prepared, the PES0.4 substrate (with 0.4 wt% zeolite) exhibited unique characteristics, i.e., increased surface porosity, lower structural parameter ( S) (from 0.78 to 0.48 mm), and enhanced water flux. The thin film nanocomposite (TFN) membrane made of this optimized substrate was also reported to exhibit higher water flux compared to the control composite membrane during forward osmosis (FO) and pressure-retarded osmosis (PRO) test, without compromising reverse solute flux. The water flux of such TFN membrane was 43% higher than the control TFC membrane (1.93 L/m2 h bar) with salt rejection recorded at 94.7%. An increment in water flux is ascribed to the reduction in structural parameter, leading to reduced ICP effect.

Fabrication of 6FDA-durene membrane incorporated with zeolite T and aminosilane grafted zeolite T for CO2/CH4 separation

NASA Astrophysics Data System (ADS)

Jusoh, Norwahyu; Fong Yeong, Yin; Keong Lau, Kok; Shariff, Azmi Mohd

2017-08-01

In the present work, zeolite T and aminosilane grafted zeolite T are embedded into 6FDA-durene polyimide phase for the fabrication of mixed matrix membranes (MMMs). FESEM images demonstrated that the improvement of interfacial adhesion between zeolite and polymer phases in MMM loaded with aminosilane grafted zeolite T was not significant as compared to zeolite T/6FDA-durene MMM. From the gas permeation test, CO2/CH4 selectivity up to 26.4 was achieved using MMM containing aminosilane grafted zeolite T, while MMM loaded with ungrafted zeolite T showed CO2/CH4 selectivity of 19.1. In addition, MMM incorporated with aminosilane grafted zeolite T particles successfully lies on Robeson upper bound 2008, which makes it an attractive candidate for CO2/CH4 separation.

Solvent-Free Synthesis of Zeolites: Mechanism and Utility.

PubMed

Wu, Qinming; Meng, Xiangju; Gao, Xionghou; Xiao, Feng-Shou

2018-05-08

Zeolites have been extensively studied for years in different areas of chemical industry, such as shape selective catalysis, ion-exchange, and gas adsorption and separation. Generally, zeolites are prepared from solvothermal synthesis in the presence of a large amounts of solvents such as water and alcohols in sealed autoclaves under autogenous pressure. Water has been regarded as essential to synthesize zeolites for fast mass transfer of reactants, but it occupies a large space in autoclaves, which greatly reduces the yield of zeolite products. Furthermore, polluted wastes and relatively high pressure due to the presence of water solvent in the synthesis also leads to environmental and safety issues. Recently, inspired by great benefits of solvent-free synthesis, including the environmental concerns, energy consumption, safety, and economic cost, researchers continually challenge the rationale of the solvent and reconsider the age-old question "Do we actually need solvents at all in zeolite synthesis?" In this Account, we briefly summarize our efforts to rationally synthesize zeolites via a solvent-free route. Our research demonstrates that a series of silica, aluminosilicate, and aluminophosphate-based zeolites can be successfully prepared by mixing, grinding, and heating starting solid materials under solvent-free conditions. Combining an organotemplate-free synthesis with a solvent-free approach maximizes the advantages resulting in a more sustainable synthetic route, which avoids using toxic and costly organic templates and the formation of harmful gases by calcination of organic templates at high temperature. Furthermore, new insights into the solvent-free crystallization process of zeolites have been provided by modern techniques such as NMR and UV-Raman spectroscopy, which should be helpful in designing new zeolite structures and developing novel routes for synthesis of zeolites. The role of water and the vital intermediates during the crystallization of

[What a physician should know about zeolites].

PubMed

Boranić, M

2000-01-01

Zeolites are natural and synthetic hydrated crystalline aluminosilicates endowed with absorptive and ion exchange properties. They have found numerous and multifarous applications--in industry as catalysts and absorbents, in water sanitation for the removal of ammonia and heavy metals, in agriculture as fertilizers, and in animal husbandry as the absorbents of excreted material and as food additives. Medical applications have included the use in filtration systems for anesthesia or dialysis and as the contrast materials in NMR imaging. Recently, zeolite powders for external use have found application as deodorants, antimycotic agents and wound dressings. Peroral use of encapsulated zeolite powders enriched with vitamins, oligoelements or other ingredients has been claimed to exert beneficial medical effects. Ingestion of zeolites may be considered analogous to the clay eating (geophagia), considered in traditional medicine as a remedy for various illnesses. Being amphoteric, zeolites are partly soluble in acid or alkaline media, but within the physiological pH range the solubility is generally low. Minimal amounts of free aluminium or silicium from the ingested zeolites are resorbed from the gut. The bulk of ingested zeolite probably remains undissolved in the gut. In view of the ion exchange properties, zeolites may be expected to change the ionic content, pH and buffering capacity of the gastrointestinal secretions and to affect the transport through the intestinal epithelium. In addition, zeolites could affect the bacterial flora and the resorption of bacterial products, vitamins and oligoelements. The contact of zeolite particles with gastrointestinal mucosa may elicit the secretion of cytokines with local and systemic actions. Reactive silicium ions might react with biomolecules of the intestinal epithelium, and if resorbed, do so in other cells. Mutagenic and carcinogenic effects of zeolite particles have been described, resembling such effects of asbestos

UTILITY OF ZEOLITES IN ARSENIC REMOVAL FROM WATER

EPA Science Inventory

Zeolites are well known for their ion exchange and adsorption properties. So far the cation exchanger properties of zeolites have been extensively studied and utilized. The anion exchanger properties of zeolites are less studied. Zeolite Faujasite Y has been used to remove arseni...

Safety and efficacy of Cardi-O-fix occluder for percutaneous closure of a patent foramen ovale

PubMed Central

Zhao, Enfa; Liu, Wenjuan; Zhang, Yushun; Cheng, Gesheng; Du, Yajuan; He, Lu; Wang, Xingye; He, Xumei

2017-01-01

Abstract Background: Amplatzer occluder and Cardio-O-fix occluder are currently used in percutaneous closure of patent foramen ovale. However, there is still a lack of relevant reports comparison the differences between them. The aim of this study was to evaluate the short-term and mid-term safety and efficacy of the Cardi-O-fix occluder in preventing recurrent cerebrovascular events in patients with a patent foramen ovale (PFO). Methods: We enrolled 246 patients (105 men) with a PFO from May 30, 2013 to March 30, 2015 in this single-center prospective study. All patients were treated by PFO interventional closure, with the Cardi-O-fix PFO occluder being used in 180 patients and the Amplatzer PFO occluder being utilized in the remaining 66 patients. After the procedure, we verified the safety and efficacy of different devices using contrast transthoracic echocardiography. Results: Neither recurrent stroke nor death was encountered during the follow-up of 12 months. Transient ischemic attack (TIA) was noted in 2 patients (1.1%) in the Cardi-O-fix PFO occluder group, and 1 patient suffered from TIA (1.5%) in the Amplatzer PFO occluder group. Among them, only 1 patient exhibited a small right to left shunt (RLS). There was no statistical difference in recurrent cerebral ischemic events. Three cases of paroxysmal atrial fibrillation were observed in the Cardi-O-fix PFO occluder group. One reverted spontaneously to sinus rhythm and the other 2 cases had pharmacologic conversion to sinus rhythm. One case of paroxysmal atrial fibrillation occurred in the Amplatzer group, which underwent pharmacologic conversion to sinus rhythm. There was no significant difference between the 2 groups regarding incidence of arrhythmia. No occluder translocation, erosion, pericardial effusion, and puncture site bleeding were observed in the 2 groups within 12 months of follow-up. The complete closure rates of the Cardi-O-fix and Amplatzer PFO occluder devices at the 12 months after the

Form Perception of Partly Occluded Shapes in 4-Month-Old Infants

ERIC Educational Resources Information Center

de Wit, Tessa C. J.; Vrins, Sven; Dejonckheere, Peter J. N.; van Lier, Rob

2008-01-01

Two habituation experiments were conducted to investigate how 4-month-old infants perceive partly occluded shapes. In the first experiment, we presented a simple, partly occluded shape to the infants until habituation was reached. Then we showed either a probable completion (one that would be predicted on the basis of both local and global cues)…

Zeolite Nanoparticles for Selective Sorption of Plasma Proteins

NASA Astrophysics Data System (ADS)

Rahimi, M.; Ng, E.-P.; Bakhtiari, K.; Vinciguerra, M.; Ahmad, H. Ali; Awala, H.; Mintova, S.; Daghighi, M.; Bakhshandeh Rostami, F.; de Vries, M.; Motazacker, M. M.; Peppelenbosch, M. P.; Mahmoudi, M.; Rezaee, F.

2015-11-01

The affinity of zeolite nanoparticles (diameter of 8-12 nm) possessing high surface area and high pore volume towards human plasma proteins has been investigated. The protein composition (corona) of zeolite nanoparticles has been shown to be more dependent on the plasma protein concentrations and the type of zeolites than zeolite nanoparticles concentration. The number of proteins present in the corona of zeolite nanoparticles at 100% plasma (in vivo state) is less than with 10% plasma exposure. This could be due to a competition between the proteins to occupy the corona of the zeolite nanoparticles. Moreover, a high selective adsorption for apolipoprotein C-III (APOC-III) and fibrinogen on the zeolite nanoparticles at high plasma concentration (100%) was observed. While the zeolite nanoparticles exposed to low plasma concentration (10%) exhibited a high selective adsorption for immunoglobulin gamma (i.e. IGHG1, IGHG2 and IGHG4) proteins. The zeolite nanoparticles can potentially be used for selectively capture of APOC-III in order to reduce the activation of lipoprotein lipase inhibition during hypertriglyceridemia treatment. The zeolite nanoparticles can be adapted to hemophilic patients (hemophilia A (F-VIII deficient) and hemophilia B (F-IX deficient)) with a risk of bleeding, and thus might be potentially used in combination with the existing therapy.

Zeolite Nanoparticles for Selective Sorption of Plasma Proteins.

PubMed

Rahimi, M; Ng, E-P; Bakhtiari, K; Vinciguerra, M; Ali Ahmad, H; Awala, H; Mintova, S; Daghighi, M; Bakhshandeh Rostami, F; de Vries, M; Motazacker, M M; Peppelenbosch, M P; Mahmoudi, M; Rezaee, F

2015-11-30

The affinity of zeolite nanoparticles (diameter of 8-12 nm) possessing high surface area and high pore volume towards human plasma proteins has been investigated. The protein composition (corona) of zeolite nanoparticles has been shown to be more dependent on the plasma protein concentrations and the type of zeolites than zeolite nanoparticles concentration. The number of proteins present in the corona of zeolite nanoparticles at 100% plasma (in vivo state) is less than with 10% plasma exposure. This could be due to a competition between the proteins to occupy the corona of the zeolite nanoparticles. Moreover, a high selective adsorption for apolipoprotein C-III (APOC-III) and fibrinogen on the zeolite nanoparticles at high plasma concentration (100%) was observed. While the zeolite nanoparticles exposed to low plasma concentration (10%) exhibited a high selective adsorption for immunoglobulin gamma (i.e. IGHG1, IGHG2 and IGHG4) proteins. The zeolite nanoparticles can potentially be used for selectively capture of APOC-III in order to reduce the activation of lipoprotein lipase inhibition during hypertriglyceridemia treatment. The zeolite nanoparticles can be adapted to hemophilic patients (hemophilia A (F-VIII deficient) and hemophilia B (F-IX deficient)) with a risk of bleeding, and thus might be potentially used in combination with the existing therapy.

Zeolite Nanoparticles for Selective Sorption of Plasma Proteins

PubMed Central

Rahimi, M.; Ng, E.-P.; Bakhtiari, K.; Vinciguerra, M.; Ahmad, H. Ali; Awala, H.; Mintova, S.; Daghighi, M.; Bakhshandeh Rostami, F.; de Vries, M.; Motazacker, M. M.; Peppelenbosch, M. P.; Mahmoudi, M.; Rezaee, F.

2015-01-01

The affinity of zeolite nanoparticles (diameter of 8–12 nm) possessing high surface area and high pore volume towards human plasma proteins has been investigated. The protein composition (corona) of zeolite nanoparticles has been shown to be more dependent on the plasma protein concentrations and the type of zeolites than zeolite nanoparticles concentration. The number of proteins present in the corona of zeolite nanoparticles at 100% plasma (in vivo state) is less than with 10% plasma exposure. This could be due to a competition between the proteins to occupy the corona of the zeolite nanoparticles. Moreover, a high selective adsorption for apolipoprotein C-III (APOC-III) and fibrinogen on the zeolite nanoparticles at high plasma concentration (100%) was observed. While the zeolite nanoparticles exposed to low plasma concentration (10%) exhibited a high selective adsorption for immunoglobulin gamma (i.e. IGHG1, IGHG2 and IGHG4) proteins. The zeolite nanoparticles can potentially be used for selectively capture of APOC-III in order to reduce the activation of lipoprotein lipase inhibition during hypertriglyceridemia treatment. The zeolite nanoparticles can be adapted to hemophilic patients (hemophilia A (F-VIII deficient) and hemophilia B (F-IX deficient)) with a risk of bleeding, and thus might be potentially used in combination with the existing therapy. PMID:26616161

Method to synthesize dense crystallized sodalite pellet for immobilizing halide salt radioactive waste

DOEpatents

Koyama, T.

1992-01-01

This report describes a method for immobilizing waste chloride salts containing radionuclides such as cesium and strontium and hazardous materials such as barium. A sodalite intermediate is prepared by mixing appropriate amounts of silica, alumina and sodium hydroxide with respect to sodalite and heating the mixture to form the sodalite intermediate and water. Heating is continued to drive off the water to form a water-free intermediate. The water-free intermediate is mixed with either waste salt or waste salt which has been contacted with zeolite to concentrate the radionuclides and hazardous material. The waste salt-intermediate mixture is then compacted and heated under conditions of heat and pressure to form sodalite with the waste salt, radionuclides and hazardous material trapped within the sodalite cage structure. This provides a final product having excellent leach resistant capabilities.

Increased thermal conductivity monolithic zeolite structures

DOEpatents

Klett, James; Klett, Lynn; Kaufman, Jonathan

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.

Zeolites on Mars: Prospects for Remote Sensing

NASA Technical Reports Server (NTRS)

Gaffney, E. S.; Singer, R. B.; Kunkle, T. D.

1985-01-01

The Martian surface composition measured by Viking can be represented by several combinations of minerals incorporating major fractions of zeolites known to occur in altered mafic rocks and polar soils on Earth. The abundant occurrence of zeolites on Mars is consistent with what is known about both the physical and chemical environment of that planet. The laboratory reflectance spectra (0.65 to 2.55 microns) of a number of relatively pure zeolite minerals and some naturally occurring zeolite-clay soils were measured. All of the spectra measured are dominated by strong absorption near 1.4 and 1.9 microns and a steep reflectance drop longward of about 2.2 microns, all of which are due to abundant H2O. Weaker water overtone bands are also apparent, and in most cases there is spectral evidence for minor Fe(3+). In these features the zeolite spectra are similar to spectra of smectite clays which have abundant interlayer water. The most diagnostic difference between clay and zeolite spectra is the total absence in the zeolites of the weak structural OH absorption.

Dynamic representation of partially occluded objects in primate prefrontal and visual cortex

PubMed Central

Choi, Hannah; Shea-Brown, Eric

2017-01-01

Successful recognition of partially occluded objects is presumed to involve dynamic interactions between brain areas responsible for vision and cognition, but neurophysiological evidence for the involvement of feedback signals is lacking. Here, we demonstrate that neurons in the ventrolateral prefrontal cortex (vlPFC) of monkeys performing a shape discrimination task respond more strongly to occluded than unoccluded stimuli. In contrast, neurons in visual area V4 respond more strongly to unoccluded stimuli. Analyses of V4 response dynamics reveal that many neurons exhibit two transient response peaks, the second of which emerges after vlPFC response onset and displays stronger selectivity for occluded shapes. We replicate these findings using a model of V4/vlPFC interactions in which occlusion-sensitive vlPFC neurons feed back to shape-selective V4 neurons, thereby enhancing V4 responses and selectivity to occluded shapes. These results reveal how signals from frontal and visual cortex could interact to facilitate object recognition under occlusion. PMID:28925354

Preparation of functionalized zeolitic frameworks

DOEpatents

Yaghi, Omar M; Hayashi, Hideki; Banerjee, Rahul; Park, Kyo Sung; Wang, Bo; Cote, Adrien P

2012-11-20

The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

Preparation of functionalized zeolitic frameworks

DOEpatents

Yaghi, Omar M.; Hayashi, Hideki; Banerjee, Rahul; Park, Kyo Sung; Wang, Bo; Cote, Adrien P.

2014-08-19

The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

Preparation of functionalized zeolitic frameworks

DOEpatents

Yaghi, Omar M; Furukawa, Hiroyasu; Wang, Bo

2013-07-09

The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

Identification and characterization of steady and occluded water in drinking water distribution systems.

PubMed

Tong, Huiyan; Zhao, Peng; Zhang, Hongwei; Tian, Yimei; Chen, Xi; Zhao, Weigao; Li, Mei

2015-01-01

Deterioration and leakage of drinking water in distribution systems have been a major issue in the water industry for years, which are associated with corrosion. This paper discovers that occluded water in the scales of the pipes has an acidic environment and high concentration of iron, manganese, chloride, sulfate and nitrate, which aggravates many pipeline leakage accidents. Six types of water samples have been analyzed under the flowing and stagnant periods. Both the water in the exterior of the tubercles and stagnant water carry suspended iron particles, which explains the occurrence of "red water" when the system hydraulic conditions change. Nitrate is more concentrated in occluded water under flowing condition in comparison with that in flowing water. However, the concentration of nitrate in occluded water under stagnant condition is found to be less than that in stagnant water. A high concentration of manganese is found to exist in steady water, occluded water and stagnant water. These findings impact secondary pollution and the corrosion of pipes and containers used in drinking water distribution systems. The unique method that taking occluded water from tiny holes which were drilled from the pipes' exteriors carefully according to the positions of corrosion scales has an important contribution to research on corrosion in distribution systems. And this paper furthers our understanding and contributes to the growing body of knowledge regarding occluded environments in corrosion scales. Copyright © 2014 Elsevier Ltd. All rights reserved.

Natural zeolites in diet or litter of broilers.

PubMed

Schneider, A F; Almeida, D S De; Yuri, F M; Zimmermann, O F; Gerber, M W; Gewehr, C E

2016-04-01

This study aims to analyse the influence of adding natural zeolites (clinoptilolite) to the diet or litter of broilers and their effects on growth performance, carcass yield and litter quality. Three consecutive flocks of broilers were raised on the same sawdust litter, from d 1 to d 42 of age, and distributed in three treatments (control with no added zeolites, addition of 5 g/kg zeolite to diet and addition of 100 g/kg zeolites to litter). The addition of zeolites to the diet or litter did not affect growth performance or carcass yield. The addition of zeolites to the diet did not influence moisture content of the litter, ammonia volatilisation was reduced only in the first flock and pH of litter was reduced in the second and third flock. However, the addition of zeolites to the litter reduced moisture content, litter pH and ammonia volatilisation in all flocks analysed. The addition of 5 g/kg zeolite to the diet in three consecutive flocks was not effective in maintaining litter quality, whereas the addition of 100 g/kg natural zeolites to sawdust litter reduced litter moisture and ammonia volatilisation in three consecutive flocks raised on the same litter.

Zeolites: Can they be synthesized by design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, M.E.

1994-09-01

Zeolites and zeolite-like molecular sieves are crystalline oxides that have high surface-to-volume ratios and are able to recognize, discriminate, and organize molecules with differences of < 1 [angstrom]. The close connection between the atomic structure and macroscopic properties of these materials has led to uses in molecular recognition. For example, zeolites and zeolite-like molecular sieves can reveal marvelous molecular recognition specificity and sensitivity that can be applied to catalysis, separations technology, and chemical sensing. Additionally, they can serve as hosts to organize guest atoms and molecules that endow composite materials with optoelectric and electrochemical properties. Because of the high levelmore » of structural control necessary to create high-performance materials with zeolites or zeolite-like molecular sieves, the design and synthesis of these solids with specific architectures and properties are highly desired. Although this lofty goal is still elusive, advances have been made to allow the serious consideration of designing molecular sieves. Here, the author covers two aspects of this ongoing effort. First, he discusses the feasibility of designing pore architectures through the use of organic structure-directing agents. Second, he explores the possibility of creating zeolites through ''Lego chemistry.''« less

Time course of spatial and feature selective attention for partly-occluded objects.

PubMed

Kasai, Tetsuko; Takeya, Ryuji

2012-07-01

Attention selects objects/groups as the most fundamental units, and this may be achieved by an attention-spreading mechanism. Previous event-related potential (ERP) studies have found that attention-spreading is reflected by a decrease in the N1 spatial attention effect. The present study tested whether the electrophysiological attention effect is associated with the perception of object unity or amodal completion through the use of partly-occluded objects. ERPs were recorded in 14 participants who were required to pay attention to their left or right visual field and to press a button for a target shape in the attended field. Bilateral stimuli were presented rapidly, and were separated, connected, or connected behind an occluder. Behavioral performance in the connected and occluded conditions was worse than that in the separated condition, indicating that attention spread over perceptual object representations after amodal completion. Consistently, the late N1 spatial attention effect (180-220 ms post-stimulus) and the early phase (230-280 ms) of feature selection effects (target N2) at contralateral sites decreased, equally for the occluded and connected conditions, while the attention effect in the early N1 latency (140-180 ms) shifted most positively for the occluded condition. These results suggest that perceptual organization processes for object recognition transiently modulate spatial and feature selection processes in the visual cortex. Copyright © 2012 Elsevier Ltd. All rights reserved.

Efficiency of basalt zeolite and Cuban zeolite to adsorb ammonia released from poultry litter.

PubMed

Nuernberg, Giselle B; Moreira, Marcelo A; Ernani, Paulo R; Almeida, Jaime A; Maciel, Tais M

2016-12-01

Confined poultry production is an important livestock activity, which generates large amounts of waste associated with the potential for environmental pollution and ammonia (NH 3 ) emissions. The release of ammonia negatively affects poultry production and decreases the N content of wastes that could be used as soil fertilizers. The objective of this study was to evaluate a low-cost, simple and rapid method to simulate ammonia emissions from poultry litter as well as to quantify the reduction in the ammonia emissions to the environment employing two adsorbent zeolites, a commercial Cuban zeolite (CZ) and a ground basalt Brazilian rock containing zeolite (BZ). The experiments were conducted in a laboratory, in 2012-2013. The zeolites were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), physical adsorption of N 2 (BET) and scanning electron microscopy (SEM). Ammonia released from poultry litter and its simulation from NH 4 OH solution presented similar capture rates of 7.99 × 10 -5 and 7.35 × 10 -5  mg/h, respectively. Both zeolites contain SiO 2 and Al 2 O 3 as major constituents, with contents of 84% and 12% in the CZ, and 51% and 12% in the BZ, respectively, besides heulandite groups. Their BET surface areas were 89.4 and 11.3 m 2  g -1 , respectively, and the two zeolites had similar surface morphologies. The zeolites successfully adsorbed the ammonia released, but CZ was more efficient than BZ, since to capture all of the ammonia 5 g of CZ and 20 g of BZ were required. This difference is due to higher values for the superficial area, porosity, CEC and acid site strength of CZ relatively to BZ. The proposed methodology was shown to be an efficient method to simulate and quantify the ammonia released from poultry litter. Copyright © 2016 Elsevier Ltd. All rights reserved.

Building zeolites from pre-crystallized units: nanoscale architecture.

PubMed

Corma, Avelino; Li, Chengeng; Moliner, Manuel

2018-01-24

Since the earlier descriptions by Barrer in the 40's on converting natural minerals into synthetic zeolites, the use of pre-crystallized zeolites as crucial inorganic directing agents to synthesize other crystalline zeolites with improved physico-chemical properties, has become a very intense and relevant research field, allowing the design, particularly in the last years, of new industrial catalysts. In the present review, we will highlight how the presence of some crystalline fragments in the synthesis media, such as small secondary building units (SBUs) or layered substructures, not only favors the crystallization of other zeolites presenting similar SBUs or layers, but also permits mostly controlling important parameters affecting to their catalytic activity (i.e. chemical composition, crystal size, or porosity, among others). In this sense, the recent advances on the preparation of 3-D and 2-D related zeolites through seeding and zeolite-to-zeolite transformation processes will be extensively revised, including their preparation in presence or absence of organic structure directing agents (OSDAs), with the aim of introducing general guidelines for designing more efficient future synthesis approaches for target zeolites. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antimicrobial properties of zeolite-X and zeolite-A ion-exchanged with silver, copper, and zinc against a broad range of microorganisms.

PubMed

Demirci, Selami; Ustaoğlu, Zeynep; Yılmazer, Gonca Altın; Sahin, Fikrettin; Baç, Nurcan

2014-02-01

Zeolites are nanoporous alumina silicates composed of silicon, aluminum, and oxygen in a framework with cations, water within pores. Their cation contents can be exchanged with monovalent or divalent ions. In the present study, the antimicrobial (antibacterial, anticandidal, and antifungal) properties of zeolite type X and A, with different Al/Si ratio, ion exchanged with Ag(+), Zn(2+), and Cu(2+) ions were investigated individually. The study presents the synthesis and manufacture of four different zeolite types characterized by scanning electron microscopy and X-ray diffraction. The ion loading capacity of the zeolites was examined and compared with the antimicrobial characteristics against a broad range of microorganisms including bacteria, yeast, and mold. It was observed that Ag(+) ion-loaded zeolites exhibited more antibacterial activity with respect to other metal ion-embedded zeolite samples. The results clearly support that various synthetic zeolites can be ion exchanged with Ag(+), Zn(2+), and Cu(2+) ions to acquire antimicrobial properties or ion-releasing characteristics to provide prolonged or stronger activity. The current study suggested that zeolite formulations could be combined with various materials used in manufacturing medical devices, surfaces, textiles, or household items where antimicrobial properties are required.

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

NASA Astrophysics Data System (ADS)

ćiçek, 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.

Early stages of zeolite growth

NASA Astrophysics Data System (ADS)

Kumar, Sandeep

Zeolites are crystalline nonporous aluminosilicates with important applications in separation, purification, and adsorption of liquid and gaseous molecules. However, an ability to tailor the zeolite microstructure, such as particle size/shape and pore-size, to make it benign for specific application requires control over nucleation and particle growth processes. But, the nucleation and crystallization mechanisms of zeolites are not fully understood. In this context, the synthesis of an all-silica zeolite with MFI-type framework has been studied extensively as a model system. Throughout chapters 2, 4 and 5, MFI growth process has been investigated by small-angle x-ray scattering (SAXS) and transmission electron microscopy (TEM). Of fundamental importance is the role of nanoparticles (~5 nm), which are present in the precursor sol, in MFI nucleation and crystallization. Formation of amorphous aggregates and their internal restructuring are concluded as essential steps in MFI nucleation. Early stage zeolite particles have disordered and less crystalline regions within, which indicates the role of structurally distributed population of nanoparticles in growth. Faceting occurs after the depletion of nanoparticles. The chapter 6 presents growth studies in silica sols prepared by using a dimer of tertaprpylammonium (TPA) and reports that MFI nucleation and crystallization are delayed with a more pronounced delay in crystal growth.

The local environment of Cu+ in Cu-Y zeolite and its relationship to the synthesis of dimethyl carbonate.

PubMed

Drake, Ian J; Zhang, Yihua; Briggs, Daniel; Lim, Bomyi; Chau, Tanguy; Bell, Alexis T

2006-06-22

Cu-exchanged Y zeolite was investigated in order to determine the location of the copper cations relative to the zeolite framework and to determine which Cu cations are active for the oxidative carbonylation of methanol to dimethyl carbonate (DMC). Cu-Y zeolite was prepared by vapor-phase exchange of H-Y with CuCl. The oxidation state, local coordination, and bond distances of Al and Cu were determined using Al K-edge and Cu K-edge X-ray absorption spectroscopy (XAS). Complimentary information was obtained by H2 temperature-programmed reduction and by in-situ infrared spectroscopy. Cu-Y has a Cu/Al ratio of unity and very little occluded CuCl. The average Al-O and Al-Cu bond distances are 1.67 angstroms and 2.79 angstroms, respectively, and the average Cu-O and Cu-Si(Al) bond distances are 1.99 angstroms and 3.13 angstroms, respectively. All of the Cu exchanged is present as Cu+ in sites I', II, and III'. Cu-Y is active for the oxidative carbonylation of methanol, and at low reactant contact time produces DMC as the primary product. With increasing reactant contact time, DMC formation decreases in preference to the formation of dimethoxy methane (DMM) and methylformate (MF). The formation of DMM and MF is attributed to the hydrogenation of DMC and the hydrogenolysis of DMM, respectively. Observation of the catalyst under reaction conditions reveals that most of the copper cations remain as Cu+, but some oxidation of Cu+ to Cu2+ does occur. It is also concluded that only those copper cations present in site II and III' positions are accessible to the reactants, and hence are catalytically active. The dominant adsorbed species on the surface are methoxy groups, and adsorbed CO is present as a minority species. The relationship of these observations to the kinetics of DMC synthesis is discussed.

Recognition of partially occluded threat objects using the annealed Hopefield network

NASA Technical Reports Server (NTRS)

Kim, Jung H.; Yoon, Sung H.; Park, Eui H.; Ntuen, Celestine A.

1992-01-01

Recognition of partially occluded objects has been an important issue to airport security because occlusion causes significant problems in identifying and locating objects during baggage inspection. The neural network approach is suitable for the problems in the sense that the inherent parallelism of neural networks pursues many hypotheses in parallel resulting in high computation rates. Moreover, they provide a greater degree of robustness or fault tolerance than conventional computers. The annealed Hopfield network which is derived from the mean field annealing (MFA) has been developed to find global solutions of a nonlinear system. In the study, it has been proven that the system temperature of MFA is equivalent to the gain of the sigmoid function of a Hopfield network. In our early work, we developed the hybrid Hopfield network (HHN) for fast and reliable matching. However, HHN doesn't guarantee global solutions and yields false matching under heavily occluded conditions because HHN is dependent on initial states by its nature. In this paper, we present the annealed Hopfield network (AHN) for occluded object matching problems. In AHN, the mean field theory is applied to the hybird Hopfield network in order to improve computational complexity of the annealed Hopfield network and provide reliable matching under heavily occluded conditions. AHN is slower than HHN. However, AHN provides near global solutions without initial restrictions and provides less false matching than HHN. In conclusion, a new algorithm based upon a neural network approach was developed to demonstrate the feasibility of the automated inspection of threat objects from x-ray images. The robustness of the algorithm is proved by identifying occluded target objects with large tolerance of their features.

21 CFR 882.5150 - Intravascular occluding catheter.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Intravascular occluding catheter. 882.5150 Section 882.5150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5150 Intravascular...

21 CFR 882.5150 - Intravascular occluding catheter.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Intravascular occluding catheter. 882.5150 Section 882.5150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5150 Intravascular...

Progress on Zeolite-membrane-aided Organic Acid Esterification

NASA Astrophysics Data System (ADS)

Makertiharta, I. G. B. N.; Dharmawijaya, P. T.

2017-07-01

Esterification is a common route to produce carboxylic acid esters as important intermediates in chemical and pharmaceutical industries. However, the reaction is equilibrium limited and needs to be driven forward by selective removal one of the products. There have been some efforts to selectively remove water from reaction mixture via several separation processes (such as pervaporation and reactive distillation). Integrated pervaporation and esterification has gained increasing attention towards. Inorganic zeolite is the most popular material for pervaporation due to its high chemical resistant and separation performance towards water. Zeolite also has proven to be an effective material in removing water from organic compound. Zeolite can act not only as selective layer but also simultaneously act as a catalyst on promoting the reaction. Hence, there are many configurations in integrating zeolite membrane for esterification reaction. As a selective layer to remove water from reaction mixture, high Si/Al zeolite is preferred to enhance its hydrophilicity. However, low Si/Al zeolite is unstable in acid condition due to dealumination thus eliminate its advantages. As a catalyst, acid zeolites (e.g. H-ZSM-5) provide protons for autoprotolysis of the carboxylic acid similar to other catalyst for esterification (e.g. inorganic acid, and ion exchange resins). There are many studies related to zeolite membrane aided esterification. This paper will give brief information related to zeolite membrane role in esterification and also research trend towards it.

Hydrothermal synthesis of free-template zeolite T from kaolin

NASA Astrophysics Data System (ADS)

Arshad, Sazmal E.; Yusslee, Eddy F.; Rahman, Md. Lutfor; Sarkar, Shaheen M.; Patuwan, Siti Z.

2017-12-01

Free-template zeolite T crystals were synthesized via hydrothermal synthesis by utilizing the activated kaolin as silica and alumina source, with the molar composition of 1 SiO2: 0.04 Al2O3: 0.26 Na2O: 0.09 K2O: 14 H2O. Observation of the formation of free-template zeolite crystals were done at temperature 90°C, 100 °C and 110 °C respectively. It was therefore determined that during the 120 h of the synthesis at 90 °C, zeolite T nucleated and formed a first competitive phase with zeolite L. As temperature increases to 100 °C, zeolite T presented itself as a major phase in the system at time 168 h. Subsequently, development of Zeolite T with second competitive phase of zeolite W was observed at temperature 110 °C. In this study, XRD and SEM instruments were used to monitor the behavior of zeolite T crystals with respect of temperature and time. By using natural resource of kaolin clay as a starting material, this paper hence aims to provide new findings in synthesis of zeolite T using low energy consumption and low production cost.

Subintimal Recanalization of Occluded Stents: The Substent Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diamantopoulos, Athanasios, E-mail: adiamant@upatras.gr; Katsanos, Konstantinos; Spiliopoulos, Stavros

2013-08-01

PurposeApplication of metal stents is complicated by neointimal hyperplasia leading to vessel restenosis and reocclusion. Treatment options in cases presenting with complete occlusion of the stented segment and recurrent critical limb ischemia (CLI) are limited. We present the option of the subintimal/substent technique in dealing with occluded stents.MethodsThe study included patients presenting with recurrent CLI due to impaired blood flow as a result of complete occlusion of previously inserted metal stents and unsuccessful intraluminal crossing of the lesion via either the antegrade or retrograde approach. In these cases, crossing the occlusion through the subintimal/substent plane was attempted. Primary end pointsmore » included technical success, safety of the procedure, clinical improvement, and limb salvage, while secondary end points were patient survival, primary patency, and vessel restenosis rates at 1-year follow-up. Study end points were calculated by Kaplan-Meier survival analysis.ResultsBetween July 2006 and October 2011, a total of 14 patients (mean age 69.14 {+-} 12.59 years, 12 men) were treated with the substent technique and included in the analysis. Technical success rate was 85.71 % (12 of 14), with a total lesion length of 193.57 {+-} 90.78 mm. The mean occluded stented segment length was 90.21 {+-} 44.34 mm. In 10 (83.33 %) of 12 cases, a new stent had to be placed by the side of the old occluded one, while the remaining two cases (16.67 %) were treated only with balloon angioplasty. No serious adverse events were noted during the immediate postprocedural period. All successfully treated patients improved clinically. Estimated limb salvage was 90.9 %, and patient survival rate was 90.0 % at 1 year's follow-up. Primary patency was 45.50 % and vessel restenosis 77.30 %.ConclusionSubintimal recanalization of occluded metal stents through the substent plane is a valuable alternative treatment option, especially in patients with recurrent CLI

Histamine-binding capacities of different natural zeolites: a comparative study.

PubMed

Selvam, Thangaraj; Schwieger, Wilhelm; Dathe, Wilfried

2018-06-07

Two different natural zeolites from Cuba and Mexico, which are already being used as contemporaneous drugs or dietary supplements in Germany and Mexico, respectively, are applied in a comparative study of their histamine-binding capacities as a function of their particle sizes. The zeolites are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and N 2 -sorption measurements (BET surface areas). The Cuban zeolite contains clinoptilolite and mordenite as major phases (78% zeolite), whereas the Mexican one contains only clinoptilolite (65% zeolite). Both zeolites are apparently free from fibrous materials according to SEM. Both zeolites adsorb significant amount of histamine under the experimental conditions. Nevertheless, the results showed that the histamine-binding capacity of the Cuban zeolite is higher than the Mexican one and the smaller the particle size of zeolite, the higher the histamine-binding capacity. This difference could be due to the variation in their mineralogical compositions resulting in varied BET surface areas. Thus, the high histamine-binding capacities of Cuban zeolites seem to be due at least partly to the presence of the large-pore zeolite mordenite, providing high total pore volumes, which will be discussed in detail. For the first time, we have shown that the mineralogical compositions of natural zeolites and their particle sizes play a key role in binding histamine, which is one of the most important regulators in human physiology.

Zeolite food supplementation reduces abundance of enterobacteria.

PubMed

Prasai, Tanka P; Walsh, Kerry B; Bhattarai, Surya P; Midmore, David J; Van, Thi T H; Moore, Robert J; Stanley, Dragana

2017-01-01

According to the World Health Organisation, antibiotics are rapidly losing potency in every country of the world. Poultry are currently perceived as a major source of pathogens and antimicrobial resistance. There is an urgent need for new and natural ways to control pathogens in poultry and humans alike. Porous, cation rich, aluminosilicate minerals, zeolites can be used as a feed additive in poultry rations, demonstrating multiple productivity benefits. Next generation sequencing of the 16S rRNA marker gene was used to phylogenetically characterize the fecal microbiota and thus investigate the ability and dose dependency of zeolite in terms of anti-pathogenic effects. A natural zeolite was used as a feed additive in laying hens at 1, 2, and 4% w/w for a 23 week period. At the end of this period cloacal swabs were collected to sample faecal microbial communities. A significant reduction in carriage of bacteria within the phylum Proteobacteria, especially in members of the pathogen-rich family Enterobacteriaceae, was noted across all three concentrations of zeolite. Zeolite supplementation of feed resulted in a reduction in the carriage of a number of poultry pathogens without disturbing beneficial bacteria. This effect was, in some phylotypes, correlated with the zeolite concentration. This result is relevant to zeolite feeding in other animal production systems, and for human pathogenesis. Copyright © 2016 Elsevier GmbH. All rights reserved.

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

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. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of SrO content on Zeolite Structure

NASA Astrophysics Data System (ADS)

Widiarti, N.; Sari, U. S.; Mahatmanti, F. W.; Harjito; Kurniawan, C.; Prasetyoko, D.; Suprapto

2018-04-01

The aims of current studies is to investigate the effect of strontium oxide content (SrO) on synthesized zeolite. Zeolite was synthesized from Tetraethyl orthosilicate (TEOS) as precursors of SiO2 and aluminum isopropoxide (AIP) precursors. The mixture was aged for 3 days and hydrothermally treated for 6 days. The SrO content was added by impregnation method. The products were then characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Surface Area Analyzer (SAA). The diffractogram confirmed the formation of Faujasite-like zeolite. However, after the addition of SrO, the crystallinity of zeolite was deformed. The diffractograms shows the amorphous phase of zeolite were decrease as the SrO content is increase. The structural changes was also observed from FTIR spectra which shows the shifting and peak formation. The surface area analysis showed that the increasing loading of SrO/Zeolites reduced the catalyst surface area.

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.

The Role of Good Form in Young Infants' Perception of Partly Occluded Objects.

ERIC Educational Resources Information Center

Johnson, Scott P.; Bremner, J. Gavin; Slater, Alan M.; Mason, Uschi C.

2000-01-01

Three experiments investigated whether 4-month-olds would attend to and utilize the global configuration ("good form") of a partly occluded, moving object to perceive its unit and coherence behind the occluder. Results indicated that curvature per se provided information in support of completion, in addition to global configuration and…

Copper-Exchanged Zeolite L Traps Oxygen

NASA Technical Reports Server (NTRS)

Sharma, Pramod K.; Seshan, Panchalam K.

1991-01-01

Brief series of simple chemical treatments found to enhance ability of zeolite to remove oxygen from mixture of gases. Thermally stable up to 700 degrees C and has high specific surface area which provides high capacity for adsorption of gases. To increase ability to adsorb oxygen selectively, copper added by ion exchange, and copper-exchanged zeolite reduced with hydrogen. As result, copper dispersed atomically on inner surfaces of zeolite, making it highly reactive to oxygen, even at room temperature. Reactivity to oxygen even greater at higher temperatures.

Zeolite Crystal Growth (ZCG) Flight on USML-2

NASA Technical Reports Server (NTRS)

Sacco, Albert, Jr.; Bac, Nurcan; Warzywoda, Juliusz; Guray, Ipek; Marceau, Michelle; Sacco, Teran L.; Whalen, Leah M.

1997-01-01

The extensive use of zeolites and their impact on the world's economy has resulted in many efforts to characterize their structure, and improve the knowledge base for nucleation and growth of these crystals. The zeolite crystal growth (ZCG) experiment on USML-2 aimed to enhance the understanding of nucleation and growth of zeolite crystals, while attempting to provide a means of controlling the defect concentration in microgravity. Zeolites A, X, Beta, and Silicalite were grown during the 16 day - USML-2 mission. The solutions where the nucleation event was controlled yielded larger and more uniform crystals of better morphology and purity than their terrestrial/control counterparts. The external surfaces of zeolite A, X, and Silicalite crystals grown in microgravity were smoother (lower surface roughness) than their terrestrial controls. Catalytic studies with zeolite Beta indicate that crystals grown in space exhibit a lower number of Lewis acid sites located in micropores. This suggests fewer structural defects for crystals grown in microgravity. Transmission electron micrographs (TEM) of zeolite Beta crystals also show that crystals grown in microgravity were free of line defects while terrestrial/controls had substantial defects.

Dry method for recycling iodine-loaded silver zeolite

DOEpatents

Thomas, Thomas R.; Staples, Bruce A.; Murphy, Llewellyn P.

1978-05-09

Fission product iodine is removed from a waste gas stream and stored by passing the gas stream through a bed of silver-exchanged zeolite until the zeolite is loaded with iodine, passing dry hydrogen gas through the bed to remove the iodine and regenerate the bed, and passing the hydrogen stream containing the hydrogen iodide thus formed through a lead-exchanged zeolite which adsorbs the radioactive iodine from the gas stream and permanently storing the lead-exchanged zeolite loaded with radioactive iodine.

Molecular Simulation of Adsorption in Zeolites

NASA Astrophysics Data System (ADS)

Bai, Peng

Zeolites are a class of crystalline nanoporous materials that are widely used as catalysts, sorbents, and ion-exchangers. Zeolites have revolutionized the petroleum industry and have fueled the 20th-century automobile culture, by enabling numerous highly-efficient transformations and separations in oil refineries. They are also posed to play an important role in many processes of biomass conversion. One of the fundamental principles in the field of zeolites involves the understanding and tuning of the selectivity for different guest molecules that results from the wide variety of pore architectures. The primary goal of my dissertation research is to gain such understanding via computer simulations and eventually to reach the level of predictive modeling. The dissertation starts with a brief introduction of the applications of zeolites and computer modeling techniques useful for the study of zeolitic systems. Chapter 2 then describes an effort to improve simulation efficiency, which is essential for many challenging adsorption systems. Chapter 3 studies a model system to demonstrate the applicability and capability of the method used for the majority of this work, configurational-bias Monte Carlo simulations in the Gibbs ensemble (CBMC-GE). After these methodological developments, Chapter 4 and 5 report a systematic parametrization of a new transferable force field for all-silica zeolites, TraPPE-zeo, and a subsequent, relatively ad-hoc extension to cation-exchanged aluminosilicates. The CBMC-GE method and the TraPPE-zeo force field are then combined to investigate some complex adsorption systems, such as linear and branched C6-C 9 alkanes in a hierarchical microporous/mesoporous material (Chapter 6), the multi-component adsorption of aqueous alcohol solutions (Chapter 7) and glucose solutions (Chapter 8). Finally, Chapter 9 describes an endeavor to screen a large number of zeolites with the purpose of finding better materials for two energy-related applications

Distribution and Determinants of Myocardial Perfusion Grade Following Late Mechanical Recanalization of Occluded Infarct-Related Arteries Postmyocardial Infarction: A Report From the Occluded Artery Trial

PubMed Central

Jorapur, Vinod; Steigen, Terje K.; Buller, Christopher E.; Dẑavík, Vladimír; Webb, John G.; Strauss, Bradley H.; Yeoh, Eunice E.S.; Kurray, Peter; Sokalski, Leszek; Machado, Mauricio C.; Kronsberg, Shari S.; Lamas, Gervasio A.; Hochman, Judith S.; John Mancini, G.B.

2010-01-01

Objective To evaluate the distribution and determinants of myocardial perfusion grade (MPG) following late recanalization of persistently occluded infarct-related arteries (IRA). Background MPG reflects microvascular integrity. It is an independent prognostic factor following myocardial infarction, but has been studied mainly in the setting of early reperfusion. The occluded artery trial (OAT) enrolled stable patients with persistently occluded IRAs beyond 24 hr and up to 28 days post-MI. Methods Myocardial blush was assessed using TIMI MPG grading in 261 patients with TIMI 3 epicardial flow following IRA PCI. Patients demonstrating impaired (0–1) versus preserved (2–3) MPG were compared with regard to baseline clinical and pre-PCI angiographic characteristics. Results Impaired MPG was observed in 60 of 261 patients (23%). By univariate analysis, impaired MPG was associated with failed fibrinolytic therapy, higher heart rate, lower systolic blood pressure, lower ejection fraction, LAD occlusion, absence of collaterals (P < 0.01) and ST elevation MI, lower diastolic blood pressure, and higher systolic sphericity index (P < 0.05). By multivariable analysis, higher heart rate, LAD occlusion, absence of collaterals and higher systolic sphericity index (P < 0.01), and lower systolic blood pressure (P < 0.05) were independently associated with impaired MPG. Conclusion Preserved microvascular integrity was present in a high proportion of patients following late recanalization of occluded IRAs post-MI. Presence of collaterals was independently associated with preserved MPG and likely accounted for the high frequency of preserved myocardial perfusion in this clinical setting. Impaired MPG was associated with baseline clinical and angiographic features consistent with larger infarct size. PMID:18798327

Catching what we can't see: manual interception of occluded fly-ball trajectories.

PubMed

Bosco, Gianfranco; Delle Monache, Sergio; Lacquaniti, Francesco

2012-01-01

Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects

Scaling Relations for Acidity and Reactivity of Zeolites

PubMed Central

2017-01-01

Zeolites are widely applied as solid acid catalysts in various technological processes. In this work we have computationally investigated how catalytic reactivity scales with acidity for a range of zeolites with different topologies and chemical compositions. We found that straightforward correlations are limited to zeolites with the same topology. The adsorption energies of bases such as carbon monoxide (CO), acetonitrile (CH3CN), ammonia (NH3), trimethylamine (N(CH3)3), and pyridine (C5H5N) give the same trend of acid strength for FAU zeolites with varying composition. Crystal orbital Hamilton populations (COHP) analysis provides a detailed molecular orbital picture of adsorbed base molecules on the Brønsted acid sites (BAS). Bonding is dominated by strong σ donation from guest molecules to the BAS for the adsorbed CO and CH3CN complexes. An electronic descriptor of acid strength is constructed based on the bond order calculations, which is an intrinsic parameter rather than adsorption energy that contains additional contributions due to secondary effects such as van der Waals interactions with the zeolite walls. The bond order parameter derived for the CH3CN adsorption complex represents a useful descriptor for the intrinsic acid strength of FAU zeolites. For FAU zeolites the activation energy for the conversion of π-adsorbed isobutene into alkoxy species correlates well with the acid strength determined by the NH3 adsorption energies. Other zeolites such as MFI and CHA do not follow the scaling relations obtained for FAU; we ascribe this to the different van der Waals interactions and steric effects induced by zeolite framework topology. PMID:29142616

Structure modification of natural zeolite for waste removal application

NASA Astrophysics Data System (ADS)

Widayatno, W. B.

2018-03-01

Tremendous industrialization in the last century has led to the generation of huge amount of waste. One of the recent hot research topics is utilizing any advance materials and methods for waste removal. Natural zeolite as an inexpensive porous material with a high abundance holds a key for efficient waste removal owing to its high surface area. However, the microporous structure of natural zeolite hinders the adsorption of waste with a bigger molecular size. In addition, the recovery of natural zeolite after waste adsorption into its pores should also be considered for continuous utilization of this material. In this study, the porosity of natural zeolite from Tasikmalaya, Indonesia, was hydrothermally-modified in a Teflon-lined autoclave filled with certain pore directing agent such as distilled water, KOH, and NH4OH to obtain hierarchical pore structure. After proper drying process, the as-treated natural zeolite is impregnated with iron cation and heat-treated at specified temperature to get Fe-embedded zeolite structure. XRD observation is carried out to ensure the formation of magnetic phase within the zeolite pores. The analysis results show the formation of maghemite phase (γ-Fe2O3) within the zeolite pore structure.

Oxidation of cyclohexane catalyzed by metal-ion-exchanged zeolites.

PubMed

Sökmen, Ilkay; Sevin, Fatma

2003-08-01

The ion-exchange rates and capacities of the zeolite NaY for the Cu(II), Co(II), and Pb(II) metal ions were investigated. Ion-exchange equilibria were achieved in approximately 72 h for all the metal ions. The maximum ion exchange of metal ions into the zeolite was found to be 120 mg Pb(II), 110 mg Cu(II), and 100 mg Co(II) per gram of zeolite NaY. It is observed that the exchange capacity of a zeolite varies with the exchanged metal ion and the amount of metal ions exchanged into zeolite decreases in the sequence Pb(II) > Cu(II) > Co(II). Application of the metal-ion-exchanged zeolites in oxidation of cyclohexane in liquid phase with visible light was examined and it is observed that the order of reactivity of the zeolites for the conversion of cyclohexane to cyclohexanone and cyclohexanol is CuY > CoY > PbY. It is found that conversion increases by increase of the empty active sites of a zeolite and the formation of cyclohexanol is favored initially, but the cyclohexanol is subsequently converted to cyclohexanone.

Positron spectroscopy studies of zeolites

NASA Astrophysics Data System (ADS)

Hung, Ku-Jung

The lineshapes of two-dimensional angular correlation of electron-positron annihilation radiation (2D-ACAR) in alumina and several zeolites were measured as a function of internal surface areas. In all cases, the lineshape parameter S from 2D-ACAR spectra were found to vary proportionally with internal surface area. In order to investigate the Bronsted acidity in NaHY zeolite, the lineshape parameter evaluation from 2D-ACAR measurements for varied acidity in NaHY zeolites by ion-exchange and thermal desorption were presented. The result from this investigation has demonstrated that the Bronsted acidity in NaHY zeolite was found to vary linearly with the lineshape parameter of the angular correlation spectrum of the sample. The lineshapes of 2D-ACAR spectra were determined for different base adsorbed HY-zeolite samples under a temperature controlled heating system in order to investigate, in-situ, the acid strength and number of Bronsted acid sites in the sample. Results have shown that the lineshape parameter of the angular correlation spectrum of the sample increases with the strength of adsorbed base and decreases with the number of Bronsted acid sites in the sample. This indicated that the lineshape parameter is sensitive to all of the strengths and concentrations of Bronsted acid sites in the HY-zeolite samples. The result from this study has also demonstrated that the large size base, pyridine, would reduce the possibility of positronium formation in the sample by filling the cage to eliminate the internal surface areas where the positroniums are likely to form. However, the small size base, ammonia, did not show any effect on the internal surface areas. Owing to the fact that this technique monitors only the Bronsted acid sites that situate on the surface which relates to the catalytic activity, there is little ambiguity about the location of the source of information obtained. The findings presented in this dissertation point out the fact that such lineshape

[Percutaneous closure of the patent ductus arteriosus in children with the Amplatzer Duct Occluder II].

PubMed

Parra-Bravo, José Rafael; Osuna-Izaguirre, Manuel Alfredo; Beirana-Palencia, Luisa; Gálvez-Cancino, Franco; Martínez-Monterrosas, Christian; Lazo-Cárdenas, César; Reyes-Vargas, César

2014-01-01

In the last decades, several devices have been used for the percutaneous closure of patent ductus arteriosus, with its own limitations and risks. The Amplatzer Duct Occluder II has been designed to overcome those limitations and reduce risks. We described our initial series of patients who underwent percutaneous closure of patent ductus arteriosus with the Amplatzer Duct Occluder II, emphasis on the technical aspects of the procedure. We reviewed the clinical records of 9 patients with patent ductus arteriosus who underwent percutaneous closure with the Amplatzer Duct Occluder II. Median age was 24 months (range 8-51 months) and the median weight was 10.7kg (range 6-16.3kg). The minimal ductus arteriosus diameter was 2.7mm (1-5mm). Implantation was successful in all cases. The devices most commonly used (33.3%) were the dimensions 4-4mm (3 patients), in 2 patients were used 3-4mm and in the rest of the patients were employed occluder other sizes. Four cases showed slight residual flow immediately after implantation. Total closure was achieved in 24h in 8 of 9 patients (89%). There was no embolization of the occluder or deaths during the procedure and we only observed one minor complication. The Amplatzer Duct Occluder II in this series was effective in 89% of the patients at 24hs after the procedure and 100% follow-up. The implantation was safe and no major complications were observed. The occlusion rate is comparable to those reported for the Amplatzer Duct Occluder I. Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

Synthesis and characterization of zeolite from coal fly ash

NASA Astrophysics Data System (ADS)

Liu, Yong; Luo, Qiong; Wang, Guodong; Li, Xianlong; Na, Ping

2018-05-01

Fly ash (FA) from coal-based thermal power plant was used to synthesize zeolite in NaOH solution with hydrothermal method in this work. Firstly, the effects of calcination and acid treatment on the removal of impurities in fly ash were studied. Then based on the pretreated FA, the effects of alkali concentration, reaction temperature and Si/Al ratio on the synthesis of zeolite were studied in detail. The mineralogy, morphology, thermal behavior, infrared spectrum and specific surface for the synthetic sample were investigated. The results indicated that calcination at 750 °C for 1.5 h can basically remove unburned carbon from FA, and 4 M hydrochloric acid treatment of calcined FA at 90 °C for 2 h will reduce the quality of about 34.3%wt, which are mainly iron, calcium and sulfur elements. The concentration of NaOH, reaction temperature and Si/Al ratio have important effect on the synthesis of zeolite. In this study, 0.5 M NaOH cannot obtain any zeolite. High temperature is beneficial to zeolite synthesis from FA, but easily lead to a variety of zeolites. The synthetic sample contains three kinds of zeolites such as zeolite P, sodalite and zeolite X, when the reaction conditions are 2 M NaOH and 120 °C for 24 h. In this research, quartz always exists in the synthetic sample, but will reduce with the increase of temperature. The synthetic zeolite has the specific surface area of about 42 m2 g‑1 and better thermal stability.

Enhanced chromium adsorption capacity via plasma modification of natural zeolites

NASA Astrophysics Data System (ADS)

Cagomoc, Charisse Marie D.; Vasquez, Magdaleno R., Jr.

2017-01-01

Natural zeolites such as mordenite are excellent adsorbents for heavy metals. To enhance the adsorption capacity of zeolite, sodium-exchanged samples were irradiated with 13.56 MHz capacitively coupled radio frequency (RF) argon gas discharge. Hexavalent chromium [Cr(VI)] was used as the test heavy metal. Pristine and plasma-treated zeolite samples were soaked in 50 mg/L Cr solution and the amount of adsorbed Cr(VI) on the zeolites was calculated at predetermined time intervals. Compared with untreated zeolite samples, initial Cr(VI) uptake was 70% higher for plasma-treated zeolite granules (50 W 30 min) after 1 h of soaking. After 24 h, all plasma-treated zeolites showed increased Cr(VI) uptake. For a 2- to 4-month period, Cr(VI) uptake increased about 130% compared with untreated zeolite granules. X-ray diffraction analyses between untreated and treated zeolite samples revealed no major difference in terms of its crystal structure. However, for plasma-treated samples, an increase in the number of surface defects was observed from scanning electron microscopy images. This increase in the number of surface defects induced by plasma exposure played a crucial role in increasing the number of active sorption sites on the zeolite surface.

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.

Copper-containing zeolite catalysts

DOEpatents

Price, Geoffrey L.; Kanazirev, Vladislav

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.

Zeolite Crystal Growth in Microgravity and on Earth

NASA Technical Reports Server (NTRS)

2003-01-01

The Center for Advanced Microgravity Materials Processing (CAMMP), a NASA-sponsored Research Partnership Center, is working to improve zeolite materials for storing hydrogen fuel. CAMMP is also applying zeolites to detergents, optical cables, gas and vapor detection for environmental monitoring and control, and chemical production techniques that significantly reduce by-products that are hazardous to the environment. Shown here are zeolite crystals (top) grown in a ground control experiment and grown in microgravity on the USML-2 mission (bottom). Zeolite experiments have also been conducted aboard the International Space Station.

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

2015-07-08

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 μm 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.

Summary Report of Laboratory Testing to Establish the Effectiveness of Proposed Treatment Methods for Unremediated and Remediated Nitrate Salt Waste Streams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anast, Kurt Roy; Funk, David John

The inadvertent creation of transuranic waste carrying hazardous waste codes D001 and D002 requires the treatment of the material to eliminate the hazardous characteristics and allow its eventual shipment and disposal at the Waste Isolation Pilot Plant (WIPP). This report documents the effectiveness of two treatment methods proposed to stabilize both the unremediated and remediated nitrate salt waste streams (UNS and RNS, respectively). The two technologies include the addition of zeolite (with and without the addition of water as a processing aid) and cementation. Surrogates were developed to evaluate both the solid and liquid fractions expected from parent waste containers,more » and both the solid and liquid fractions were tested. Both technologies are shown to be effective at eliminating the characteristic of ignitability (D001), and the addition of zeolite was determined to be effective at eliminating corrosivity (D002), with the preferred option1 of zeolite addition currently planned for implementation at the Waste Characterization, Reduction, and Repackaging Facility. During the course of this work, we established the need to evaluate and demonstrate the effectiveness of the proposed remedy for debris material, if required. The evaluation determined that Wypalls absorbed with saturated nitrate salt solutions exhibit the ignitability characteristic (all other expected debris is not classified as ignitable). Follow-on studies will be developed to demonstrate the effectiveness of stabilization for ignitable Wypall debris. Finally, liquid surrogates containing saturated nitrate salts did not exhibit the characteristic of ignitability in their pure form (those neutralized with Kolorsafe and mixed with sWheat did exhibit D001). As a result, additional nitrate salt solutions (those exhibiting the oxidizer characteristic) will be tested to demonstrate the effectiveness of the remedy.« less

Amodal representation of occluded surfaces: role of invisible stimuli in apparent motion correspondence.

PubMed

Shimojo, S; Nakayama, K

1990-01-01

A series of demonstrations were created where the perceived depth of targets was controlled by stereoscopic disparity. A closer object (a cloud) was made to jump back and forth horizontally, partially occluding a farther object (a full moon). The more distant moon appeared stationary even though the unoccluded portion of it, a crescent, changed position. Reversal of the relative depth of the moon and cloud gave a totally different percept: the crescent appeared to flip back and forth in the front depth plane. Thus, the otherwise-robust apparent motion of the moon crescents was completely abolished in the cloud-closer case alone. This motion-blocking effect is attributed to the 'amodal presence' of the occluded surface continuing behind the occluding surface. To measure the effect of this occluded 'invisible' surface quantitatively, a bistable apparent motion display was used (Ramachandran and Anstis 1983a): two small rectangular-shaped targets changed their positions back and forth between two frames, and the disparity of a large centrally positioned rectangle was varied. When the perceived depths supported the possibility of amodal completion behind the large rectangle, increased vertical motion of the targets was found, suggesting that the amodal presence of the targets behind the occluder had effectively changed the center position of the moving targets for purposes of motion correspondence. Amodal contours are literally 'invisible', yet it is hypothesized that they have a neural representation at sufficiently early stages of visual processing to alter the correspondence solving process for apparent motion.

Zeolites with Continuously Tuneable Porosity**

PubMed Central

Wheatley, Paul S; Chlubná-Eliášová, Pavla; Greer, Heather; Zhou, Wuzong; Seymour, Valerie R; Dawson, Daniel M; Ashbrook, Sharon E; Pinar, Ana B; McCusker, Lynne B; Opanasenko, Maksym; Čejka, Jiří; Morris, Russell E

2014-01-01

Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure-directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneable surface area and micropore volume over a wide range can be prepared. This means that a particular surface area or micropore volume can be precisely tuned. The range of porosity we can target covers the whole range of useful zeolite porosity: from small pores consisting of 8-rings all the way to extra-large pores consisting of 14-rings. PMID:25284344

Zeolites in the Pine Ridge Indian Reservation, South Dakota

USGS Publications Warehouse

Raymond, William H.; Bush, Alfred L.; Gude, Arthur J.

1982-01-01

Zeolites of possible commercial value occur in the Brule Formation of Oligocene age and the Sharps Formation (Harksen, 1961) of Miocene age which crop out in a wide area in the northern part of the Pine Ridge Indian Reservation. The thickness of the zeolite-bearing Interval and the extent of areas within the Interval which contain significant amounts of zeolites are far greater than was expected prior to this investigation. The shape of the zeolite-bearing Interval is tabular and the dimensions of Its exposure are roughly 10 ml x 200 mi x 150 ft (16 km x 160 km x 45 m) thick. Within the study area, there are tracts in which the zeolite resource potential is significant (see pl. 2). This report is intended to inform the Oglala Sioux Tribe of some of the most promising zeolite occurrences. Initial steps can then be taken by the Tribe toward possible development of the resources, should they wish to do so. The data contained herein identify areas of high zeolite potential, but are not adequate to establish economic value for the deposits. If development is recommended by the tribal government, we suggest that the tribal government contact companies involved in research and production of natural zeolites and provide them with the data in this report.

'water splitting' by titanium exchanged zeolite A. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuznicki, S.M.; Eyring, E.M.

1978-09-01

Visually detectable and chromatographically and mass spectrally identified hydrogen gas evolves from titanium (III) exchanged zeolite A immersed in water and illuminated with visible light. Titanium(III) exchanged zeolite X and zeolite Y do not produce this reaction. A photochemically produced, oxygenated titanium free radical (detected by electron spin resonance) not previously described is the species in the zeolite that reduces protons to molecular hydrogen. The other product of this reduction step is a nonradical, oxygenated titanium species of probable empirical formula TiO4. Heating the spent oxygenated titanium containing zeolite A under vacuum at 375 C restores over fifty percent ofmore » the free radical. Unlike previously reported systems, heating does not restore the original aquotitanium(III) species in the zeolite. Thus a means other than heating must be found to achieve a closed photochemical cycle that harnesses visible solar energy in the production of molecular hydrogen. The titanium exchanged zeolite A does, however, lend itself to a thermolysis of water previously described by Kasai and Bishop. (Author)« less

Catalytic Oxidation by Transition Metal Ions in Zeolites.

DTIC Science & Technology

1984-09-28

exotic schemes were developed. It was previously demonstrated that MoCI5 may be reacted with a HYu (here Yu denotes a steam-stabilized or...34ultrastable" zeolite) to form a MoYu zeolite and HC1 which is removed from the system.1 In this study, MoYu zeolites have been prepared by reacting HYu with Mo

Molecular simulations and experimental studies of zeolites

NASA Astrophysics Data System (ADS)

Moloy, Eric C.

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, are important ion-exchange materials. Zeolites also play important roles as molecular sieves and catalysts. For all that is known about zeolites, much remains a mystery. How, for example, can the well established metastability of these structures be explained? What is the role of water with respect to the formation, stabilization, and dynamical properties? This dissertation addresses these questions mainly from a modeling perspective, but also with some experimental work as well. The first discussion addresses a special class of zeolites: pure-silica zeolites. Experimental enthalpy of formation data are combined with molecular modeling to address zeolitic metastability. Molecular modeling is used to calculate internal surface areas, and a linear relationship between formation enthalpy and internal surface areas is clearly established, producing an internal surface energy of approximately 93 mJ/m2. Nitrate bearing sodalite and cancrinite have formed under the caustic chemical conditions of some nuclear waste processing centers in the United States. These phases have fouled expensive process equipment, and are the primary constituents of the resilient heels in the bottom of storage tanks. Molecular modeling, including molecular mechanics, molecular dynamics, and density functional theory, is used to simulate these materials with respect to structure and dynamical properties. Some new, very interesting results are extracted from the simulation of anhydrous Na6[Si6Al 6O24] sodalite---most importantly, the identification of two distinct

Advances in nanosized zeolites

NASA Astrophysics Data System (ADS)

Mintova, Svetlana; Gilson, Jean-Pierre; Valtchev, Valentin

2013-07-01

This review highlights recent developments in the synthesis of nanosized zeolites. The strategies available for their preparation (organic-template assisted, organic-template free, and alternative procedures) are discussed. Major breakthroughs achieved by the so-called zeolite crystal engineering and encompass items such as mastering and using the physicochemical properties of the precursor synthesis gel/suspension, optimizing the use of silicon and aluminium precursor sources, the rational use of organic templates and structure-directing inorganic cations, and careful adjustment of synthesis conditions (temperature, pressure, time, heating processes from conventional to microwave and sonication) are addressed. An on-going broad and deep fundamental understanding of the crystallization process, explaining the influence of all variables of this complex set of reactions, underpins an even more rational design of nanosized zeolites with exceptional properties. Finally, the advantages and limitations of these methods are addressed with particular attention to their industrial prospects and utilization in existing and advanced applications.

Zeolite-like liquid crystals

NASA Astrophysics Data System (ADS)

Poppe, Silvio; Lehmann, Anne; Scholte, Alexander; Prehm, Marko; Zeng, Xiangbing; Ungar, Goran; Tschierske, Carsten

2015-10-01

Zeolites represent inorganic solid-state materials with porous structures of fascinating complexity. Recently, significant progress was made by reticular synthesis of related organic solid-state materials, such as metal-organic or covalent organic frameworks. Herein we go a step further and report the first example of a fluid honeycomb mimicking a zeolitic framework. In this unique self-assembled liquid crystalline structure, transverse-lying π-conjugated rod-like molecules form pentagonal channels, encircling larger octagonal channels, a structural motif also found in some zeolites. Additional bundles of coaxial molecules penetrate the centres of the larger channels, unreachable by chains attached to the honeycomb framework. This creates a unique fluid hybrid structure combining positive and negative anisotropies, providing the potential for tuning the directionality of anisotropic optical, electrical and magnetic properties. This work also demonstrates a new approach to complex soft-matter self-assembly, by using frustration between space filling and the entropic penalty of chain extension.

UTILITY OF ZEOLITES IN HAZARDOUS METAL REMOVAL FROM WATER

EPA Science Inventory

Zeolites are well known for their ion exchange, adsorption and acid catalysis properties. Different inorganic pollutants have been removed from water at room temperature by using synthetic zeolites. Zeolite Faujasite Y has been used to remove inorganic pollutants including arseni...

Ammonium removal from high-strength aqueous solutions by Australian zeolite.

PubMed

Wijesinghe, D Thushari N; Dassanayake, Kithsiri B; Sommer, Sven G; Jayasinghe, Guttila Y; J Scales, Peter; Chen, Deli

2016-07-02

Removal of ammonium nitrogen (NH4(+)-N) particularly from sources which are highly rich in nitrogen is important for addressing environmental pollution. Zeolites, aluminosilicate minerals, are commonly used as commercial adsorbents and ion-exchange medium in number of commercial applications due to its high adsorption capacity of ammonium (NH4(+)). However, detailed investigations on NH4(+) adsorption and ion exchange capacities of Australian natural zeolites are rare, particularly under higher NH4(+) concentrations in the medium. Therefore, this study was conducted to determine NH4(+) adsorption characteristics of Australian natural zeolites at high NH4(+) concentrations with and without other chemical compounds in an aqueous solution. Results showed that initial NH4(+) concentration, temperature, reaction time, and pH of the solution had significant effects on NH4(+) adsorption capacity of zeolite. Increased retention time and temperature generally had a positive impact on adsorption. Freundlich model fitted well with adsorption process of Australian natural zeolites; however, Langmuir model had best fitted for the adsorption process of sodium (Na(+)) treated zeolites. NaCl treatment increased the NH4(+) adsorption capacity of Australian zeolites by 25% at 1000 mg-N, NH4(+) solution. The maximum adsorption capacity of both natural Australian zeolites and Na(+) treated zeolites were estimated as 9.48 and 11.83 mg-N/g, respectively, which is lower than many zeolites from other sources. Compared to the NH4(+) only medium, presence of other competitive ions and acetic acid in the medium (resembling composition in digested swine manure slurries) reduced NH4(+) removal of natural and Na(+) treated zeolites by 44% and 57%, respectively. This suggests detailed investigations are required to determine practically achievable NH4(+) -N removal potential of zeolites for applications in complex mediums such as animal manure slurries.

Zeolite-catalyzed hydrogenation of carbon dioxide and ethene.

PubMed

Chan, Bun; Radom, Leo

2008-07-30

Ab initio molecular orbital theory and density functional theory calculations have been used to study the three-stage zeolite-catalyzed hydrogenation of CO2 to methanol and the hydrogenation of C2H 4 to ethane, with the aim of designing an effective zeolite catalyst for these reactions. Both Brønsted acid (XH) and alkali metal (XM) sites in model zeolites (-X-Al-XH- or -X-Al-XM-) have been examined. It is found that appropriately designed zeolites can provide excellent catalysis for these reactions, particularly for the hydrogenation of CO2, HCO2H and CH2O, with uncatalyzed barriers of more than 300 kJ mol(-1) being reduced to as little as 17 kJ mol(-1) (in the case of CH2O). The reaction barrier depends on the acidity of the XH moiety or the nature of the metal cation M in the XM moiety, and the basicity of the adjacent X group in the catalyst. For a catalyst based on alkali metal zeolites (XM), the catalytic activity is relatively insensitive to the nature of X in the XM group. As a result, the catalytic activity for these types of zeolites increases as X becomes more basic. We propose that alkali metal zeolites with Ge and N incorporated into the framework could be very effective catalysts for hydrogenation processes.

Applications of zeolites in biotechnology and medicine - a review.

PubMed

Bacakova, Lucie; Vandrovcova, Marta; Kopova, Ivana; Jirka, Ivan

2018-05-01

Zeolites are microporous tectosilicates of natural or synthetic origin, which have been extensively used in various technological applications, e.g. as catalysts and as molecular sieves, for separating and sorting various molecules, for water and air purification, including removal of radioactive contaminants, for harvesting waste heat and solar heat energy, for adsorption refrigeration, as detergents, etc. These applications of zeolites were typically related with their porous character, their high adsorption capacity, and their ion exchange properties. This review is focused on potential or already practically implemented applications of zeolites in biotechnology and medicine. Zeolites are promising for environment protection, detoxication of animal and human organisms, improvement of the nutrition status and immunity of farm animals, separation of various biomolecules and cells, construction of biosensors and detection of biomarkers of various diseases, controlled drug and gene delivery, radical scavenging, and particularly tissue engineering and biomaterial coating. As components of scaffolds for bone tissue engineering, zeolites can deliver oxygen to cells, can stimulate osteogenic cell differentiation, and can inhibit bone resorption. Zeolites can also act as oxygen reservoirs, and can improve cell performance in vascular and skin tissue engineering and wound healing. When deposited on metallic materials for bone implantation, zeolite films showed anticorrosion effects, and improved the osseointegration of these implants. In our studies, silicalite-1 films deposited on silicon or stainless steel substrates improved the adhesion, growth, viability and osteogenic differentiation of human osteoblast-like Saos-2 cells. Zeolites have been clinically used as components of haemostatics, e.g. in the Advanced Clotting Sponge, as gastroprotective drugs, e.g. Absorbatox® 2.4D, or as antioxidative agents (Klinobind®). Some zeolites are highly cytotoxic and carcinogenic

The Effect of Zeolite Composition and Grain Size on Gas Sensing Properties of SnO₂/Zeolite Sensor.

PubMed

Sun, Yanhui; Wang, Jing; Li, Xiaogan; Du, Haiying; Huang, Qingpan; Wang, Xiaofeng

2018-01-29

In order to improve the sensing properties of tin dioxide gas sensor, four kinds of different SiO₂/Al₂O₃ ratio, different particle size of MFI type zeolites (ZSM-5) were coated on the SnO₂ to prepared zeolite modified gas sensors, and the gas sensing properties were tested. The measurement results showed that the response values of ZSM-5 zeolite (SiO₂/Al₂O₃ = 70, grain size 300 nm) coated SnO₂ gas sensors to formaldehyde vapor were increased, and the response to acetone decreased compared with that of SnO₂ gas sensor, indicating an improved selectivity property. The other three ZSM-5 zeolites with SiO₂/Al₂O₃ 70, 150 and 470, respectively, and grain sizes all around 1 μm coated SnO₂ sensors did not show much difference with SnO₂ sensor for the response properties to both formaldehyde and acetone. The sensing mechanism of ZSM-5 modified sensors was briefly analyzed.

ACTIVE DELIVERY CABLE TUNED TO DEVICE DEPLOYMENT STATE: ENHANCED VISIBILITY OF NITINOL OCCLUDERS DURING PRE-CLINICAL INTERVENTIONAL MRI

PubMed Central

Bell, Jamie A.; Saikus, Christina E.; Ratnayaka, Kanishka; Barbash, Israel M.; Faranesh, Anthony Z.; Franson, Dominique N.; Sonmez, Merdim; Slack, Michael C.; Lederman, Robert J.; Kocaturk, Ozgur

2012-01-01

Purpose To develop an active delivery system that enhances visualization of nitinol cardiac occluder devices during deployment under real-time MRI. Materials and Methods We constructed an active delivery cable incorporating a loopless antenna and a custom titanium microscrew to secure the occluder devices. The delivery cable was tuned and matched to 50Ω at 64 MHz with the occluder device attached. We used real-time balanced SSFP in a wide-bore 1.5T scanner. Device-related images were reconstructed separately and combined with surface-coil images. The delivery cable was tested in vitro in a phantom and in vivo in swine using a variety of nitinol cardiac occluder devices. Results In vitro, the active delivery cable provided little signal when the occluder device was detached and maximal signal with the device attached. In vivo, signal from the active delivery cable enabled clear visualization of occluder device during positioning and deployment. Device release resulted in decreased signal from the active cable. Post-mortem examination confirmed proper device placement. Conclusions The active delivery cable enhanced the MRI depiction of nitinol cardiac occluder devices during positioning and deployment, both in conventional and novel applications. We expect enhanced visibility to contribute to effectiveness and safety of new and emerging MRI-guided treatments. PMID:22707441

Catching What We Can't See: Manual Interception of Occluded Fly-Ball Trajectories

PubMed Central

Bosco, Gianfranco; Delle Monache, Sergio; Lacquaniti, Francesco

2012-01-01

Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects

Engineering Options Assessment Report. Nitrate Salt Waste Stream Processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anast, Kurt Roy

2015-11-13

This report examines and assesses the available systems and facilities considered for carrying out remediation activities on remediated nitrate salt (RNS) and unremediated nitrate salt (UNS) waste containers at Los Alamos National Laboratory (LANL). The assessment includes a review of the waste streams consisting of 60 RNS, 29 above-ground UNS, and 79 candidate below-ground UNS containers that may need remediation. The waste stream characteristics were examined along with the proposed treatment options identified in the Options Assessment Report . Two primary approaches were identified in the five candidate treatment options discussed in the Options Assessment Report: zeolite blending and cementation.more » Systems that could be used at LANL were examined for housing processing operations to remediate the RNS and UNS containers and for their viability to provide repackaging support for remaining LANL legacy waste.« less

Engineering Options Assessment Report: Nitrate Salt Waste Stream Processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anast, Kurt Roy

2015-11-18

This report examines and assesses the available systems and facilities considered for carrying out remediation activities on remediated nitrate salt (RNS) and unremediated nitrate salt (UNS) waste containers at Los Alamos National Laboratory (LANL). The assessment includes a review of the waste streams consisting of 60 RNS, 29 aboveground UNS, and 79 candidate belowground UNS containers that may need remediation. The waste stream characteristics were examined along with the proposed treatment options identified in the Options Assessment Report . Two primary approaches were identified in the five candidate treatment options discussed in the Options Assessment Report: zeolite blending and cementation.more » Systems that could be used at LANL were examined for housing processing operations to remediate the RNS and UNS containers and for their viability to provide repackaging support for remaining LANL legacy waste.« less

Cationic surfactants-modified natural zeolites: improvement of the excipients functionality.

PubMed

Krajisnik, Danina; Milojević, Maja; Malenović, Anđelija; Daković, Aleksandra; Ibrić, Svetlana; Savić, Snezana; Dondur, Vera; Matijasević, Srđan; Radulović, Aleksandra; Daniels, Rolf; Milić, Jela

2010-10-01

In this study an investigation of cationic surfactants-modified natural zeolites as drug formulation excipient was performed. The aim of this work was to carry out a study of the purified natural zeolitic tuff with high amount of clinoptilolite as a potential carrier for molecules of pharmaceutical interest. Two cationic surfactants (benzalkonium chloride and hexadecyltrimethylammonium bromide) were used for modification of the zeolitic surface in two levels (equal to and twice as external cation-exchange capacity of the zeolitic tuff). Prepared samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric, high-performance liquid chromatography analysis, and powder flow determination. Different surfactant/zeolite composites were used for additional investigation of three model drugs: diclofenac diethylamine, diclofenac sodium, and ibuprofen by means of adsorption isotherm measurements in aqueous solutions. The modified zeolites with two levels of surfactant coverage within the short activation time were prepared. Determination of flow properties showed that modification of zeolitic surface reflected on powder flow characteristics. Investigation of the model drugs adsorption on the obtained composites revealed that a variation between adsorption levels was influenced by the surfactant type and the amount present at the surface of the composites. In vitro release profiles of the drugs from the zeolite-surfactant-drug composites revealed that sustained drug release could be attained over a period of 8 hours. The presented results for drug uptake by surfactant-zeolite composites and the afterward drug release demonstrated the potential use of investigated modified natural zeolite as excipients for advanced excipients in drug formulations.

Modulation of occluding junctions alters the hematopoietic niche to trigger immune activation

PubMed Central

Khadilkar, Rohan J; Vogl, Wayne; Goodwin, Katharine

2017-01-01

Stem cells are regulated by signals from their microenvironment, or niche. During Drosophila hematopoiesis, a niche regulates prohemocytes to control hemocyte production. Immune challenges activate cell-signalling to initiate the cellular and innate immune response. Specifically, certain immune challenges stimulate the niche to produce signals that induce prohemocyte differentiation. However, the mechanisms that promote prohemocyte differentiation subsequent to immune challenges are poorly understood. Here we show that bacterial infection induces the cellular immune response by modulating occluding-junctions at the hematopoietic niche. Occluding-junctions form a permeability barrier that regulates the accessibility of prohemocytes to niche derived signals. The immune response triggered by infection causes barrier breakdown, altering the prohemocyte microenvironment to induce immune cell production. Moreover, genetically induced barrier ablation provides protection against infection by activating the immune response. Our results reveal a novel role for occluding-junctions in regulating niche-hematopoietic progenitor signalling and link this mechanism to immune cell production following infection. PMID:28841136

AMPLATZER versus Figulla occluder for transcatheter patent foramen ovale closure.

PubMed

Trabattoni, Daniela; Gaspardone, Achille; Sgueglia, Gregory A; Fabbiocchi, Franco; Gioffrè, Gaetano; Montorsi, Piero; Calligaris, Giuseppe; Iamele, Maria; De Santis, Antonella; Bartorelli, Antonio L

2017-04-20

The aim of this observational study was to compare acute and 12-month results of percutaneous closure of patent foramen ovale (PFO) with two occluder devices. Between June 2007 and October 2014, 406 consecutive patients (48.1±13.3 years, 243 women) underwent percutaneous PFO closure with either the AMPLATZER (n=179) or the Figulla (n=227) device after a stroke or a transient ischaemic attack ascribed to the PFO. A right-to-left shunt grade >1 was previously detected in all patients and atrial septal aneurysm was present in 111 (27.5%) patients. Patients were followed up with a contrast transthoracic echocardiogram and clinically at 24 hours, six months, and 12 months after the procedure. A high procedural success was observed in both groups. Despite a trend towards a higher incidence of acute residual shunt immediately after device deployment among Figulla occluder patients, a residual grade ≥2 right-to-left shunt was observed in 4.5% of patients, independently of the device used for PFO closure. The only difference reported after Figulla device implantation was a lower rate of supraventricular arrhythmias (9% vs. 17%, p=0.02). According to this two-centre study, PFO closure appears safe and effective with the Figulla occluder as well as with the AMPLATZER device.

Recent Advances on Bioethanol Dehydration using Zeolite Membrane

NASA Astrophysics Data System (ADS)

Makertihartha, I. G. B. N.; Dharmawijaya, P. T.; Wenten, I. G.

2017-07-01

Renewable energy has gained increasing attention throughout the world. Bioethanol has the potential to replace existing fossil fuel usage without much modification in existing facilities. Bioethanol which generally produced from fermentation route produces low ethanol concentration. However, fuel grade ethanol requires low water content to avoid engine stall. Dehydration process has been increasingly important in fuel grade ethanol production. Among all dehydration processes, pervaporation is considered as the most promising technology. Zeolite possesses high potential in pervaporation of bioethanol into fuel grade ethanol. Zeolite membrane can either remove organic (ethanol) from aqueous mixture or water from the mixture, depending on the framework used. Hydrophilic zeolite membrane, e.g. LTA, can easily remove water from the mixture leaving high ethanol concentration. On the other hand, hydrophobic zeolite membrane, e.g. silicate-1, can remove ethanol from aqueous solution. This review presents the concept of bioethanol dehydration using zeolite membrane. Special attention is given to the performance of selected pathway related to framework selection.

Method for the recovery of silver from silver zeolite

DOEpatents

Reimann, G.A.

1985-03-05

High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

Method for the recovery of silver from silver zeolite

DOEpatents

Reimann, George A.

1986-01-01

High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

Impact of steel slag on the ammonium adsorption by zeolite and a new configuration of zeolite-steel slag substrate for constructed wetlands.

PubMed

Shi, Pengbo; Jiang, Yingbo; Zhu, Hongtao; Sun, Dezhi

2017-07-01

The CaO dissolution from slag, as well as the effects of influencing parameters (i.e. pH and Ca 2+ concentration) on the ammonium adsorption onto zeolite, was systematically studied in this paper. Modeling results of Ca 2+ and OH - release from slag indicated that pseudo-second-order reaction had a better fitness than pseudo-first-order reaction. Changing pH value from 7 to 12 resulted in a drastic reduction of the ammonium adsorption capacity on zeolite, from the peak adsorption capacity at pH 7. High Ca 2+ concentration in solution also inhibited the adsorption of ammonium onto zeolite. There are two proposed mechanisms for steel slag inhibiting the ammonium adsorption capacity of zeolite. On the one hand, OH - released from steel slag can react with ammonium ions to produce the molecular form of ammonia (NH 3 ·H 2 O), which would cause the dissociation of NH 4 + from zeolite. On the other hand, Ca 2+ could replace the NH 4 + ions to adhere onto the surface of zeolite. An innovative substrate filling configuration with zeolite placed upstream of the steel slag was then proposed to eliminate the disadvantageous effects of steel slag. Experimental results showed that this novel filling configuration was superior to two other filling configurations in terms of ammonium removal.

Recognition of 3-D Scene with Partially Occluded Objects

NASA Astrophysics Data System (ADS)

Lu, Siwei; Wong, Andrew K. C...

1987-03-01

This paper presents a robot vision system which is capable of recognizing objects in a 3-D scene and interpreting their spatial relation even though some objects in the scene may be partially occluded by other objects. An algorithm is developed to transform the geometric information from the range data into an attributed hypergraph representation (AHR). A hypergraph monomorphism algorithm is then used to compare the AHR of objects in the scene with a set of complete AHR's of prototypes. The capability of identifying connected components and interpreting various types of edges in the 3-D scene enables us to distinguish objects which are partially blocking each other in the scene. Using structural information stored in the primitive area graph, a heuristic hypergraph monomorphism algorithm provides an effective way for recognizing, locating, and interpreting partially occluded objects in the range image.

Safety, dose, and timing of reteplase in treating occluded central venous catheters in children with cancer.

PubMed

Terrill, Kelly R; Lemons, Richard S; Goldsby, Robert E

2003-11-01

Recombinant tissue plasminogen activator, alteplase, began to be commonly used to restore the patency of occluded central venous catheters (CVCs) as urokinase production was halted in the late 1990s. However, alteplase often requires an extended dwell time to restore patency to occluded CVCs. In adults, reteplase, a newer thrombolytic agent, has been reported to restore patency to CVCs in 30 minutes. The authors prospectively evaluated the safety and efficacy of reteplase in restoring patency to occluded CVCs in children with cancer. This was a dose escalation trial. The dose of reteplase was initiated at 0.1 units and increased by increments of 0.1 units to a maximum dose of 0.4 units. Each dose was tested on at least three participants. Time to patency after reteplase administration was recorded by nurses caring for the patients. Attempts to access the line occurred every 15 minutes for 1 hour. CVCs that remained occluded after 1 hour were treated with alteplase. Reteplase was administered to 15 clotted CVCs. Twelve of the 15 were cleared with an average dwell time of 38 minutes. The time to patency did not appear to correlate with the dose. No adverse events were reported. Reteplase can restore patency to occluded CVCs in a pediatric population. Reteplase appears to have comparable efficacy with alteplase, but reteplase may require shorter dwell times. A prospective, randomized, clinical trial is warranted to determine whether reteplase is as effective as alteplase in restoring patency to occluded CVCs.

Dioctahedral Phyllosilicates Versus Zeolites and Carbonates Versus Zeolites Competitions as Constraints to Understanding Early Mars Alteration Conditions

NASA Astrophysics Data System (ADS)

Viennet, Jean-Christophe; Bultel, Benjamin; Riu, Lucie; Werner, Stephanie C.

2017-11-01

Widespread occurrence of Fe,Mg-phyllosilicates has been observed on Noachian Martian terrains. Therefore, the study of Fe,Mg-phyllosilicate formation, in order to characterize early Martian environmental conditions, is of particular interest to the Martian community. Previous studies have shown that the investigation of Fe,Mg-smectite formation alone helps to describe early Mars environmental conditions, but there are still large uncertainties in terms of pH range, oxic/anoxic conditions, etc. Interestingly, carbonates and/or zeolites have also been observed on Noachian surfaces in association with the Fe,Mg-phyllosilicates. Consequently, the present study focuses on the dioctahedral/trioctahedral phyllosilicate/carbonate/zeolite formation as a function of various CO2 contents (100% N2, 10% CO2/90% N2, and 100% CO2), from a combined approach including closed system laboratory experiments for 3 weeks at 120°C and geochemical simulations. The experimental results show that as the CO2 content decreases, the amount of dioctahedral clay minerals decreases in favor of trioctahedral minerals. Carbonates and dioctahedral clay minerals are formed during the experiments with CO2. When Ca-zeolites are formed, no carbonates and dioctahedral minerals are observed. Geochemical simulation aided in establishing pH as a key parameter in determining mineral formation patterns. Indeed, under acidic conditions dioctahedral clay minerals and carbonate minerals are formed, while trioctahedral clay minerals are formed in basic conditions with a neutral pH value of 5.98 at 120°C. Zeolites are favored from pH ≳ 7.2. The results obtained shed new light on the importance of dioctahedral clay minerals versus zeolites and carbonates versus zeolites competitions to better define the aqueous alteration processes throughout early Mars history.

Synthesis and Characterization of Zeolite Na-Y and Its Conversion to the Solid Acid Zeolite H-Y

ERIC Educational Resources Information Center

Warner, Terence E.; Klokker, Mads Galsgaard; Nielsen, Ulla Gro

2017-01-01

Zeolite Y has an iconic crystal structure, but more importantly, the hydrogen modification zeolite H-Y is the classic example of a solid acid which is used extensively as a catalyst in the oil industry. This metastable compound cannot be synthesized directly, which creates an opportunity to discuss various preparative strategies with the students,…

Transcatheter closure of ventricular septal defects with nitinol wire occluders of type patent ductus arteriosus.

PubMed

Wierzyk, Arkadiusz; Szkutnik, Małgorzata; Fiszer, Roland; Banaszak, Paweł; Pawlak, Szymon; Białkowski, Jacek

2014-01-01

Ventricular septal defects closure (VSD) depending on the anatomy and clinical setting can be performed surgically or by a hybrid and transcatheter approach. Two cases of children with VSD will be presented. Patients' defects were closed with various types of occluders made of nitinol wire mesh occluder, patent ductus arteriosus (PDA) type. The first case was a 2.5-year-old boy after cardiosurgical correction of tetralogy of Fallot (TOF). After the procedure, a significant haemodynamic residual VSD was observed, which was not successfully closed during the subsequent reoperation. Despite pharmacological treatment, symptoms of heart failure were observed in this patient. In echocardiographic images the residual VSD was presented as a tunnel-like dissection of the ventricular septum (length 6 mm and diameter 3.4 mm). The defect was closed via arterial access with an Amplatzer Duct Occluder II (ADO II). The procedure was successfully performed without any medical complications. In this child, a significant shunt reduction and a noticeable improvement in the patient's clinical status and diminished symptoms of heart failure were noticed. The second patient was a 4-year-old girl suffering from a multi-perforated perimembranous VSD accompanied by a ventricular septal defect with aneurysm. The defect was closed by a venous approach with a PDA Cardio-O-Fix occluder (very similar to ADO I). No short-term or long-term complications were visible during or after the procedure. Only a mild residual shunt through the VSD was observed 6 months afterwards. Transcatheter VSD closure with a proper morphology, with occluders of type Amplatzer Duct Occluder ADO I or ADO II, constitutes a safe and effective therapeutic alternative.

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 (γ-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.

A Hierarchical MFI Zeolite with a Two-Dimensional Square Mesostructure.

PubMed

Shen, Xuefeng; Mao, Wenting; Ma, Yanhang; Xu, Dongdong; Wu, Peng; Terasaki, Osamu; Han, Lu; Che, Shunai

2018-01-15

A conceptual design and synthesis of ordered mesoporous zeolites is a challenging research subject in material science. Several seminal articles report that one-dimensional (1D) mesostructured lamellar zeolites are possibly directed by sheet-assembly of surfactants, which collapse after removal of intercalated surfactants. However, except for one example of two-dimensional (2D) hexagonal mesoporous zeolite, no other zeolites with ordered 2D or three-dimensional (3D) mesostructures have been reported. An ordered 2D mesoporous zeolite can be templated by a cylindrical assembly unit with specific interactions in the hydrophobic part. A template molecule with azobenzene in the hydrophobic tail and diquaternary ammonium in the hydrophilic head group directs hierarchical MFI zeolite with a 2D square mesostructure. The material has an elongated octahedral morphology, and quaternary, ordered, straight, square channels framed by MFI thin sheets expanded along the a-c planes and joined with 90° rotations. The structural matching between the cylindrical assembly unit and zeolite framework is crucial for mesostructure construction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors.

PubMed

Coutino-Gonzalez, Eduardo; Baekelant, Wouter; Dieu, Bjorn; Roeffaers, Maarten B J; Hofkens, Johan

2016-11-15

Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film.

Applications of natural zeolites on agriculture and food production.

PubMed

Eroglu, Nazife; Emekci, Mevlut; Athanassiou, Christos G

2017-08-01

Zeolites are crystalline hydrated aluminosilicates with remarkable physical and chemical properties, which include losing and receiving water in a reverse way, adsorbing molecules that act as molecular sieves, and replacing their constituent cations without structural change. The commercial production of natural zeolites has accelerated during the last 50 years. The Structure Commission of the International Zeolite Association recorded more than 200 zeolites, which currently include more than 40 naturally occurring zeolites. Recent findings have supported their role in stored-pest management as inert dust applications, pesticide and fertilizer carriers, soil amendments, animal feed additives, mycotoxin binders and food packaging materials. There are many advantages of inert dust application, including low cost, non-neurotoxic action, low mammalian toxicity and safety for human consumption. The latest consumer trends and government protocols have shifted toward organic origin materials to replace synthetic chemical products. In the present review, we summarize most of the main uses of zeolites in food and agruculture, along with the with specific paradigms that illustrate their important role. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

PubMed Central

Dieu, Bjorn; Roeffaers, Maarten B.J.; Hofkens, Johan

2016-01-01

Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film. PMID:27911397

Growth of zeolite crystals in the microgravity environment of space

NASA Technical Reports Server (NTRS)

Sacco, A., Jr.; Sand, L. B.; Collette, D.; Dieselman, K.; Crowley, J.; Feitelberg, A.

1986-01-01

Zeolites are hydrated, crystalline aluminosilicates with alkali and alkaling earth metals substituted into cation vacancies. Typically zeolite crystals are 3 to 8 microns. Larger cyrstals are desirable. Large zeolite crystals were produced (100 to 200 microns); however, they have taken restrictively long times to grow. It was proposed if the rate of nucleation or in some other way the number of nuclei can be lowered, fewer, larger crystals will be formed. The microgravity environment of space may provide an ideal condition to achieve rapid growth of large zeolite crystals. The objective of the project is to establish if large zeolite crystals can be formed rapidly in space.

Effect of alkali-treatment on the characteristics of natural zeolites with different compositions.

PubMed

Ates, Ayten

2018-08-01

A series of natural zeolites with different compositions were modified by post-synthesis modification with sodium hydroxide (NaOH) solution. Natural and modified zeolites were characterized by XRD, SEM, nitrogen adsorption, FTIR, zeta potential and temperature programmed desorption of ammonia (NH 3 -TPD). The adsorption capacities of these samples were evaluated by the adsorption of manganese from aqueous solution. The treatment with NaOH led to a decrease in the surface area and microporosity of all natural zeolites as well as partly damage of the zeolite structure depending on zeolite composition. In addition, the amount of weak, medium and strong acid sites in the zeolites was changed significantly by NaOH treatment depending on zeolite composition. The NaOH treatment resulted in a four-fold improvement in adsorption capacity of natural zeolite originated from Bigadic and a twofold decrease in that of the natural zeolite originated from Manisa-Gordes. Although the improved adsorption capacity might be mainly due to modification of porosity in the zeolites and formation of hydroxysodalite, the reduced adsorption capacity of the zeolite might be mainly due to a significant deformation of the zeolite structure. The pseudo-second-order kinetic model for the adsorption of manganese on all natural and modified zeolites fits well. Copyright © 2018 Elsevier Inc. All rights reserved.

Preparation of zeolite from incinerator ash and its application for the remediation of selected inorganic pollutants: A greener approach

NASA Astrophysics Data System (ADS)

Iqra, J.; Faryal, M.; Uzaira, R.; Noshaba, T.

2014-06-01

Zeolites are potential materials and can conveniently be processed as adsorbents for the removal of environmental pollutants. A wide range of commercial zeolites have been marketed but due to high cost are of limited use. The present research offers a green approach for the synthesis of zeolite using Incinerator waste (ash) as precursor. The significance rests on the conversion of hazardous waste into a useful resource (adsorbent).Incinerator ash (IA) was converted hydrothermally under strongly alkaline conditions into zeolite (ZIA). The synthesized ZIA was applied as virgin adsorbent in batch mode for the removal of primary metal pollutants of Cadmium, Chromium and Lead. The residual concentration of each metal was analyzed on Flame Atomic Absorption Spectrophotometer. Each series of batch was conducted at four varying induced concentration of metal salts as a function of time. The synthesized adsorbent was characterized on FTIR spectrophotometer to assess the involvement of functional group in metal binding to adsorbent surface. The results depicted the performance of ZIA (1mg/Kg) in removing 99.5 %, 84% and 78% of Cadmium, Chromium and Lead, respectively, upon adsorbate-adsorbent contact for 30 minutes, at lower dose of ZIA. It was also found that higher is the induced concentration, less is the removal efficiency. It may be due to limiting factor of adsorbent dose. Correlation matrix suggests positive relationship of Pb and Cr, Pb and Cd, Cr and Cd. No negative correlation was found. The study recommends the reutilization of Incinerator ash as a potential adsorbent, which can greatly enhance the sustainability of useful resources.

A database of new zeolite-like materials.

PubMed

Pophale, Ramdas; Cheeseman, Phillip A; Deem, Michael W

2011-07-21

We here describe a database of computationally predicted zeolite-like materials. These crystals were discovered by a Monte Carlo search for zeolite-like materials. Positions of Si atoms as well as unit cell, space group, density, and number of crystallographically unique atoms were explored in the construction of this database. The database contains over 2.6 M unique structures. Roughly 15% of these are within +30 kJ mol(-1) Si of α-quartz, the band in which most of the known zeolites lie. These structures have topological, geometrical, and diffraction characteristics that are similar to those of known zeolites. The database is the result of refinement by two interatomic potentials that both satisfy the Pauli exclusion principle. The database has been deposited in the publicly available PCOD database and in www.hypotheticalzeolites.net/database/deem/. This journal is © the Owner Societies 2011

Nanodispersed Suspensions of Zeolite Catalysts for Converting Dimethyl Ether into Olefins

NASA Astrophysics Data System (ADS)

Kolesnichenko, N. V.; Yashina, O. V.; Ezhova, N. N.; Bondarenko, G. N.; Khadzhiev, S. N.

2018-01-01

Nanodispersed suspensions that are effective in DME conversion and stable in the reaction zone in a three-phase system (slurry reactor) are obtained from MFI zeolite commercial samples (TsVM, IK-17-1, and CBV) in liquid media via ultrasonic treatment (UST). It is found that the dispersion medium, in which ultrasound affects zeolite commercial sample, has a large influence on particle size in the suspension. UST in the aqueous medium produces zeolite nanoparticles smaller than 50 nm, while larger particles of MFI zeolite samples form in silicone or hydrocarbon oils. Spectral and adsorption data show that when zeolites undergo UST in an aqueous medium, the acid sites are redistributed on the zeolite surface and the specific surface area of the mesopores increases. Preliminary UST in aqueous media of zeolite commercial samples (TsVM, IK-17-1, and CBV) affects the catalytic properties of MFI zeolite nanodispersed suspensions. The selectivity of samples when paraffins and olefins form is largely due to superacid sites consisting of OH groups of hydroxonium ion H3O+.

Synthesis of Zeolites Using the ADOR (Assembly-Disassembly-Organization-Reassembly) Route

PubMed Central

Wheatley, Paul S.; Čejka, Jiří; Morris, Russell E.

2016-01-01

Zeolites are an important class of materials that have wide ranging applications such as heterogeneous catalysts and adsorbents which are dependent on their framework topology. For new applications or improvements to existing ones, new zeolites with novel pore systems are desirable. We demonstrate a method for the synthesis of novel zeolites using the ADOR route. ADOR is an acronym for Assembly, Disassembly, Organization and Reassembly. This synthetic route takes advantage of the assembly of a relatively poorly stable that which can be selectively disassembled into a layered material. The resulting layered intermediate can then be organized in different manners by careful chemical manipulation and then reassembled into zeolites with new topologies. By carefully controlling the organization step of the synthetic pathway, new zeolites with never before seen topologies are capable of being synthesized. The structures of these new zeolites are confirmed using powder X-ray diffraction and further characterized by nitrogen adsorption and scanning electron microscopy. This new synthetic pathway for zeolites demonstrates its capability to produce novel frameworks that have never been prepared by traditional zeolite synthesis techniques. PMID:27078165

Synthesis of Zeolites Using the ADOR (Assembly-Disassembly-Organization-Reassembly) Route.

PubMed

Wheatley, Paul S; Čejka, Jiří; Morris, Russell E

2016-04-03

Zeolites are an important class of materials that have wide ranging applications such as heterogeneous catalysts and adsorbents which are dependent on their framework topology. For new applications or improvements to existing ones, new zeolites with novel pore systems are desirable. We demonstrate a method for the synthesis of novel zeolites using the ADOR route. ADOR is an acronym for Assembly, Disassembly, Organization and Reassembly. This synthetic route takes advantage of the assembly of a relatively poorly stable that which can be selectively disassembled into a layered material. The resulting layered intermediate can then be organized in different manners by careful chemical manipulation and then reassembled into zeolites with new topologies. By carefully controlling the organization step of the synthetic pathway, new zeolites with never before seen topologies are capable of being synthesized. The structures of these new zeolites are confirmed using powder X-ray diffraction and further characterized by nitrogen adsorption and scanning electron microscopy. This new synthetic pathway for zeolites demonstrates its capability to produce novel frameworks that have never been prepared by traditional zeolite synthesis techniques.

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. Copyright © 2014 Elsevier B.V. All rights reserved.

[Adsorption of phenol chemicals by surfactant-modified zeolites].

PubMed

Xie, Jie; Wang, Zhe; Wu, De-Yi; Li, Chun-Jie

2012-12-01

Two kinds of zeolites were prepared from fly ash and modified by surfactant subsequently. Surfactant-modified zeolites were studied for adsorption of phenol chemicals (phenol, p-chlorphenol, bisphenol A). It showed that the adsorption affinity of zeolite to phenol chemicals was significantly improved after surfactant modification. The adsorption isotherms of phenol chemicals were well fitted by the Langmuir isotherm. For the two surfactant-surfactant modified zeolites, the maximum adsorption amounts of phenol, p-chlorphenol, and bisphenol A calculated from the Langmuir equation were 37.7, 52.36, 90.9 mg x g(-1) and 10.7, 22.83, 56.8 mg x g(-1), respectively. When pH values of solutions were higher than the pK(a) values of phenol chemicals, the removal efficiencies were getting higher with the increase of pH values. The octanol/water partition coefficient (K(ow)) was also found to be an important factor affecting adsorption of phenol chemicals by the modified zeolites. Higher K(ow) value, which means the greater hydrophobicity of the chemicals, resulted in a higher removal.

Inhibition of palm oil oxidation by zeolite nanocrystals.

PubMed

Tan, Kok-Hou; Awala, Hussein; Mukti, Rino R; Wong, Ka-Lun; Rigaud, Baptiste; Ling, Tau Chuan; Aleksandrov, Hristiyan A; Koleva, Iskra Z; Vayssilov, Georgi N; Mintova, Svetlana; Ng, Eng-Poh

2015-05-13

The efficiency of zeolite X nanocrystals (FAU-type framework structure) containing different extra-framework cations (Li(+), Na(+), K(+), and Ca(2+)) in slowing the thermal oxidation of palm oil is reported. The oxidation study of palm oil is conducted in the presence of zeolite nanocrystals (0.5 wt %) at 150 °C. Several characterization techniques such as visual analysis, colorimetry, rheometry, total acid number (TAN), FT-IR spectroscopy, (1)H NMR spectroscopy, and Karl Fischer analyses are applied to follow the oxidative evolution of the oil. It was found that zeolite nanocrystals decelerate the oxidation of palm oil through stabilization of hydroperoxides, which are the primary oxidation product, and concurrently via adsorption of the secondary oxidation products (alcohols, aldehydes, ketones, carboxylic acids, and esters). In addition to the experimental results, periodic density functional theory (DFT) calculations are performed to elucidate further the oxidation process of the palm oil in the presence of zeolite nanocrystals. The DFT calculations show that the metal complexes formed with peroxides are more stable than the complexes with alkenes with the same ions. The peroxides captured in the zeolite X nanocrystals consequently decelerate further oxidation toward formation of acids. Unlike the monovalent alkali metal cations in the zeolite X nanocrystals (K(+), Na(+), and Li(+)), Ca(2+) reduced the acidity of the oil by neutralizing the acidic carboxylate compounds to COO(-)(Ca(2+))1/2 species.

Developments in Young Infants' Reasoning about Occluded Objects

ERIC Educational Resources Information Center

Aguiar, Andrea; Baillargeon, Renee

2002-01-01

Eight experiments were conducted to examine 3- and 3.5-month-old infants' responses to occlusion events. The results revealed two developments, one in infants' knowledge of when objects should and should not be occluded and the other in infants' ability to posit additional objects to make sense of events that would otherwise violate their…

Dispersible Exfoliated Zeolite Nanosheets and Their Application as a Selective Membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varoon, Kumar; Zhang, Xueyi; Elyassi, Bahman

2011-10-06

Thin zeolite films are attractive for a wide range of applications, including molecular sieve membranes, catalytic membrane reactors, permeation barriers, and low-dielectric-constant materials. Synthesis of thin zeolite films using high-aspect-ratio zeolite nanosheets is desirable because of the packing and processing advantages of the nanosheets over isotropic zeolite nanoparticles. Attempts to obtain a dispersed suspension of zeolite nanosheets via exfoliation of their lamellar precursors have been hampered because of their structure deterioration and morphological damage (fragmentation, curling, and aggregation). We demonstrated the synthesis and structure determination of highly crystalline nanosheets of zeolite frameworks MWW and MFI. The purity and morphological integritymore » of these nanosheets allow them to pack well on porous supports, facilitating the fabrication of molecular sieve membranes.« less

Composite zeolite membranes

DOEpatents

Nenoff, Tina M.; Thoma, Steven G.; Ashley, Carol S.; Reed, Scott T.

2002-01-01

A new class of composite zeolite membranes and synthesis techniques therefor has been invented. These membranes are essentially defect-free, and exhibit large levels of transmembrane flux and of chemical and isotopic selectivity.

Percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder.

PubMed

Xi, Er-Ping; Zhu, Jian; Zhu, Shui-Bo; Yin, Gui-Lin; Liu, Yong; Dong, Yong-Qiang; Zhang, Yu; Xia, Feng

2012-11-01

Ventricular septal defects resulting from post-traumatic cardiac injury are very rare. Percutaneous closure has emerged as a method for treating this disorder. We wish to report our experience in three patients who underwent percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder. We treated three patients with post-traumatic ventricular septal defects caused by stab wounds with knives. After the heart wound was repaired, patient examinations revealed ventricular septal defects with pulmonary/systemic flow ratios (Qp/Qs) of over 1.7. The post-traumatic ventricular septal defects were closed percutaneously with a patent ductus arteriosus occluder (Lifetech Scientific (Shenzhen) Co., LTD, Guangdong, China) utilizing standard techniques. Post-operative transthoracic echocardiography revealed no residual left-to-right shunt and indicated normal ventricular function. In addition, 320-slice computerized tomography showed that the occluder was well placed and exhibited normal morphology. Our experiences indicate that closure of a post-traumatic ventricular septal defect using a patent ductus arteriosus occluder is feasible, safe, and effective.

Percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder

PubMed Central

Xi, Er-Ping; Zhu, Jian; Zhu, Shui-Bo; Yin, Gui-Lin; Liu, Yong; Dong, Yong-Qiang; Zhang, Yu; Xia, Feng

2012-01-01

OBJECTIVE: Ventricular septal defects resulting from post-traumatic cardiac injury are very rare. Percutaneous closure has emerged as a method for treating this disorder. We wish to report our experience in three patients who underwent percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder. METHODS: We treated three patients with post-traumatic ventricular septal defects caused by stab wounds with knives. After the heart wound was repaired, patient examinations revealed ventricular septal defects with pulmonary/systemic flow ratios (Qp/Qs) of over 1.7. The post-traumatic ventricular septal defects were closed percutaneously with a patent ductus arteriosus occluder (Lifetech Scientific (Shenzhen) Co., LTD, Guangdong, China) utilizing standard techniques. RESULTS: Post-operative transthoracic echocardiography revealed no residual left-to-right shunt and indicated normal ventricular function. In addition, 320-slice computerized tomography showed that the occluder was well placed and exhibited normal morphology. CONCLUSION: Our experiences indicate that closure of a post-traumatic ventricular septal defect using a patent ductus arteriosus occluder is feasible, safe, and effective. PMID:23184204

Photodynamic therapy for occluded biliary metal stents

NASA Astrophysics Data System (ADS)

Roche, Joseph V. E.; Krasner, Neville; Sturgess, R.

1999-02-01

In this abstract we describe the use of photodynamic therapy (PDT) to recanalize occluded biliary metal stents. In patients with jaundice secondary to obstructed metal stents PDT was carried out 72 hours after the administration of m THPC. Red laser light at 652 nm was delivered endoscopically at an energy intensity of 50 J/cm. A week later endoscopic retrograde cholangiogram showed complete recanalization of the metal stent.

Engineering of Transition Metal Catalysts Confined in Zeolites

PubMed Central

2018-01-01

Transition metal–zeolite composites are versatile catalytic materials for a wide range of industrial and lab-scale processes. Significant advances in fabrication and characterization of well-defined metal centers confined in zeolite matrixes have greatly expanded the library of available materials and, accordingly, their catalytic utility. In this review, we summarize recent developments in the field from the perspective of materials chemistry, focusing on synthesis, postsynthesis modification, (operando) spectroscopy characterization, and computational modeling of transition metal–zeolite catalysts. PMID:29861546

Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors

PubMed Central

Zheng, Yangong; Li, Xiaogan; Dutta, Prabir K.

2012-01-01

The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors. PMID:22666081

Activity of titania and zeolite samples dosed with triethylamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Caitlin; Gole, James L.; Brauer, Jonathan

2016-01-01

Certain properties of titania and the ammonium- and proton-form of Y zeolites (silica/alumina ratio of 5.2) were explored before and after treatment by triethylamine (TEA). The effect of the triethylamine upon the physical and chemical properties of both titania and the zeolite were characterized by physical and chemical adsorption methods. BET surface area data showed enhanced surface area of the TEA-treated nanotitania over the untreated nanotitania whereas the TEA-treated zeolite showed a considerable decrease in surface area compared to the untreated zeolite. TPD of the TEA-treated Y zeolite showed that weakly adsorbed TEA left the surface between 150 and 300more » oC; strongly adsorbed TEA decomposed to ethylene and ammonia at higher temperatures. XPS, IR, and Raman spectroscopies, powder XRD, and 27Al MAS-NMR spectroscopy were used to further characterize the changes introduced by in-situ nitridation. Pre-adsorbed triethylamine decorated acid sites so as to neutralize these sites for the reaction of methanol to dimethylether. Carbon monoxide and ormaldehyde, products of the methanol probe reaction, were observed-- suggesting that basic sites are present in this treated zeolite and titania.« less

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

Using natural clinoptilolite zeolite as an amendment in vermicomposting of food waste.

PubMed

Zarrabi, Mansur; Mohammadi, Ali Akbar; Al-Musawi, Tariq J; Najafi Saleh, Hossein

2018-06-02

The effect of adding different proportions of natural clinoptilolite zeolite (5 and 10%) to food waste vermicomposting was investigated by assessing the physicochemical characteristics, worms' growth, and maturation time of finished vermicompost in comparison with the vermicompost prepared with no amendment (control). Vermicomposting was performed in 18 plastic containers for 70 days. The experimental results showed that the carbon-to-nitrogen (C/N) ratios were 15.85, 10.75, and 8.94 for 5 and 10% zeolite concentration and control after 70 days, respectively. The addition of zeolite could facilitate organic matter degradation and increase the total nitrogen content by adsorption of ammonium ions. Increasing the proportion of zeolite from 0% (control) to 10% decreased the ammonia escape by 25% in the final vermicompost. The natural zeolite significantly reduced the electrical conductivity (EC). At the end of the process, salinity uptake efficiency was 39.23% for 5% zeolite treatment and 45.23% for 10% zeolite treatment. The pH values at 5 and 10% zeolite-amended treatments were 7.31 and 7.57, respectively, in comparison to 7.10 in the control. The maturation time at the end of vermicomposting decreased with increasing zeolite concentration. The vermicompost containing 5 and 10% zeolite matured in 49 and 42 days, respectively, in comparison to 56 days for the control. With the use of an initial ten immature Eisenia fetida worms, the number of mature worms in the 10% zeolite treatment was 26 more than that in the 5% zeolite treatment (21 worms) and 9 more than that in the control treatment (17 worms). Significantly, natural zeolite showed a beneficial effect on the characteristics of the end-product when used in the vermicomposting of food waste.

Mineral resource of the month: natural and synthetic zeolites

USGS Publications Warehouse

Virta, Robert L.

2008-01-01

Volcanic rocks containing natural zeolites — hydrated aluminosilicate minerals that contain alkaline and alkaline-earth metals — have been mined worldwide for more than 1,000 years for use as cements and building stone. For centuries, people thought natural zeolites occurred only in small amounts inside cavities of volcanic rock. But in the 1950s and early 1960s, large zeolite deposits were discovered in volcanic tuffs in the western United States and in marine tuffs in Italy and Japan. And since then, similar deposits have been found around the world, from Hungary to Cuba to New Zealand. The discovery of these larger deposits made commercial mining of natural zeolite possible.

Antifungal activities against toxigenic Fusarium specie and deoxynivalenol adsorption capacity of ion-exchanged zeolites.

PubMed

Savi, Geovana D; Cardoso, William A; Furtado, Bianca G; Bortolotto, Tiago; Zanoni, Elton T; Scussel, Rahisa; Rezende, Lucas F; Machado-de-Ávila, Ricardo A; Montedo, Oscar R K; Angioletto, Elidio

2018-03-04

Zeolites are often used as adsorbents materials and their loaded cations can be exchanged with metal ions in order to add antimicrobial properties. The aim of this study was to use the 4A zeolite and its derived ion-exchanged forms with Zn 2+ , Li + , Cu 2+ and Co 2+ in order to evaluate their antifungal properties against Fusarium graminearum, including their capacity in terms of metal ions release, conidia germination and the deoxynivalenol (DON) adsorption. The zeolites ion-exchanged with Li + , Cu 2+ , and Co 2+ showed an excellent antifungal activity against F. graminearum, using an agar diffusion method, with a zone of inhibition observed around the samples of 45.3 ± 0.6 mm, 25.7 ± 1.5 mm, and 24.7 ± 0.6 mm, respectively. Similar results using agar dilution method were found showing significant growth inhibition of F. graminearum for ion-exchanged zeolites with Zn 2+ , Li + , Cu 2+ , and Co 2+ . The fungi growth inhibition decreased as zeolite-Cu 2+ >zeolite-Li + >zeolite-Co 2+ >zeolite-Zn 2+ . In addition, the conidia germination was strongly affected by ion-exchanged zeolites. With regard to adsorption capacity, results indicate that only zeolite-Li + were capable of DON adsorption significantly (P < 0.001) with 37% at 2 mg mL -1 concentration. The antifungal effects of the ion-exchanged zeolites can be ascribed to the interactions of the metal ions released from the zeolite structure, especially for zeolite-Li + , which showed to be a promising agent against F. graminearum and its toxin.

Hydrogen Purification Using Natural Zeolite Membranes

NASA Technical Reports Server (NTRS)

DelValle, William

2003-01-01

The School of Science at Universidad del Turabo (UT) have a long-lasting investigation plan to study the hydrogen cleaning and purification technologies. We proposed a research project for the synthesis, phase analysis and porosity characterization of zeolite based ceramic perm-selective membranes for hydrogen cleaning to support NASA's commitment to achieving a broad-based research capability focusing on aerospace-related issues. The present study will focus on technology transfer by utilizing inorganic membranes for production of ultra-clean hydrogen for application in combustion. We tested three different natural zeolite membranes (different particle size at different temperatures and time of exposure). Our results show that the membranes exposured at 900 C for 1Hr has the most higher permeation capacity, indicated that our zeolite membranes has the capacity to permeate hydrogen.

Efficacy of a Creon delayed-release pancreatic enzyme protocol for clearing occluded enteral feeding tubes.

PubMed

Stumpf, Janice L; Kurian, Rebecca M; Vuong, Jennifer; Dang, Kimberlyn; Kraft, Michael D

2014-04-01

Alkalinized Viokase pancreatic enzyme tablets restored patency to 71.9% of occluded Dobhoff tubes in a prospective study. After removal of Viokase tablets from the US market, the hospital protocol for unclogging enteral feeding tubes was adapted to use Creon pancreatic enzyme delayed-release capsules, despite the lack of published data. To evaluate the effectiveness of a Creon-based protocol to clear occluded enteral feeding tubes. This retrospective study included all adult and pediatric patients seen in the emergency department or in an inpatient setting who received Creon 12 000 units lipase delayed-release capsule dissolved in a solution of sodium bicarbonate 650 mg and sterile water for clearing occluded enteral feeding tubes between May 1 and November 30, 2010. The Creon protocol was deemed effective if tube clearance was documented in the medical record or if enteral feedings were resumed with no note regarding tube replacement. Alkalinized Creon delayed-release capsules were administered to 83 patients with a total of 118 clogged tubes. Three poorly documented cases and 5 tubes with mechanical clogs were excluded from data analysis. Patency was restored to 53 of 110 (48.2%) occluded tubes. More than 1 treatment course was attempted in 5 cases, with success in 3. An alkalinized Creon pancreatic enzyme protocol was effective in clearing approximately half of the occluded enteral feeding tubes in this retrospective study, an efficacy rate much less than that previously reported in the literature with a Viokase-based protocol.

Utilization of Natural Zeolite from Ponorogo and Purworejo for Naphthol Substance Adsorption

NASA Astrophysics Data System (ADS)

Imandiani, Sundus; Indira, Christine; Johan, Anthony; Budiyono

2018-02-01

Indonesia has many zeolite producing areas yet untapped. Researchers developed the utilization of natural zeolites useful for the adsorption of naphthol dyes commonly found in batik waste. In this study researchers used natural zeolites from Purworejo and Ponorogo that are activated using hydrochloric acid that is used for adsorption. The purpose of this research is to know the effect of natural zeolite activation from Ponorogo and Purworejo on the effectiveness of adsorption of naphthol dyes widely used in batik industry. Natural zeolite was activated using HCl concentration of 1.3N; 1.8N; 3.2N; and 3.9N for 60 minutes. The methods are preparation of natural zeolite from Purworejo and Ponorogo, dealumination using hydrochloric acid, adsorption process of naphthol dyes using activated zeolite, and test of adsorption result with uv-vis spectrophotometry. The test results showed that the higher HCl concentration will increase adsorption capacity. This can be known from the concentration of naphthol dye which decreased both using natural zeolite Ponorogo and Purworejo. While the effectiveness of adsorption shows natural zeolite Purworejo has a greater adsorption capacity than Ponorogo with optimum conditions of dealumination using concentration HCl 3,9N.

Numerical procedure to determine geometric view factors for surfaces occluded by cylinders

NASA Technical Reports Server (NTRS)

Sawyer, P. L.

1978-01-01

A numerical procedure was developed to determine geometric view factors between connected infinite strips occluded by any number of infinite circular cylinders. The procedure requires a two-dimensional cross-sectional model of the configuration of interest. The two-dimensional model consists of a convex polygon enclosing any number of circles. Each side of the polygon represents one strip, and each circle represents a circular cylinder. A description and listing of a computer program based on this procedure are included in this report. The program calculates geometric view factors between individual strips and between individual strips and the collection of occluding cylinders.

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 ...

Cotton-Top Tamarins' ("Saguinus Oedipus") Expectations about Occluded Objects: A Dissociation between Looking and Reaching Tasks

ERIC Educational Resources Information Center

Santos, Laurie R.; Seelig, David; Hauser, Marc D.

2006-01-01

Recent work with human infants and toddlers suggests a dissociation between performance on looking and reaching tasks. Specifically, infants appear to generate accurate representations of occluded objects and their actions when tested in expectancy violation looking tasks but often fail to use this information when reaching for occluded objects.…

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

Carbon dioxide capture utilizing zeolites synthesized with paper sludge and scrap-glass.

PubMed

Espejel-Ayala, F; Corella, R Chora; Pérez, A Morales; Pérez-Hernández, R; Ramírez-Zamora, R M

2014-12-01

The present work introduces the study of the CO2 capture process by zeolites synthesized from paper sludge and scrap glass. Zeolites ZSM-5, analcime and wairakite were produced by means of two types of Structure Directing Agents (SDA): tetrapropilamonium (TPA) and ethanol. On the one hand, zeolite ZSM-5 was synthesized using TPA; on the other hand, analcime and wairakite were produced with ethanol. The temperature programmed desorption (TPD) technique was performed for determining the CO2 sorption capacity of these zeolites at two sorption temperatures: 50 and 100 °C. CO2 sorption capacity of zeolite ZSM-5 synthesized at 50 °C was 0.683 mmol/g representing 38.2% of the value measured for a zeolite ZSM-5 commercial. Zeolite analcime showed a higher CO2 sorption capacity (1.698 mmol/g) at 50 °C and its regeneration temperature was relatively low. Zeolites synthesized in this study can be used in the purification of biogas and this will produce energy without increasing the atmospheric CO2 concentrations. © The Author(s) 2014.

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.

Removal of ammonium from municipal landfill leachate using natural zeolites.

PubMed

Ye, Zhihong; Wang, Jiawen; Sun, Lingyu; Zhang, Daobin; Zhang, Hui

2015-01-01

Ammonium ion-exchange performance of the natural zeolite was investigated in both batch and column studies. The effects of zeolite dosage, contact time, stirring speed and pH on ammonium removal were investigated in batch experiments. The result showed that ammonium removal efficiency increased with an increase in zeolite dosage from 25 to 150 g/L, and an increase in stirring speed from 200 to 250 r/min. But further increase in zeolite dosage and stirring speed would result in an unpronounced increase of ammonium removal. The optimal pH for the removal of ammonium was found as 7.1. In the column studies, the effect of flow rate was investigated, and the total ammonium removal percentage during 180 min operation time decreased with the flow rate though the ion-exchange capacity varied to a very small extent with the flow rate ranging from 4 to 9 mL/min. The spent zeolite was regenerated by sodium chloride solution and the ammonia removal capacity of zeolite changed little or even increased after three regeneration cycles.

Xylenes transformation over zeolites ZSM-5 ruled by acidic properties

NASA Astrophysics Data System (ADS)

Gołąbek, Kinga; Tarach, Karolina A.; Góra-Marek, Kinga

2018-03-01

The studies presented in this work offer an insight into xylene isomerization process, followed by 2D COS analysis, in the terms of different acidity of microporous zeolites ZSM-5. The isomerisation reaction proceeded effectively over zeolites ZSM-5 of Si/Al equal of 12 and 32. Among them, the Al-poorer zeolite (Si/Al = 32) was found to offer the highest conversion and selectivity to p-xylene with the lowest number of disproportionation products, both in ortho- and meta-xylene transformation. Further reduction of Brønsted acidity facilitated the disproportionation path (zeolites of Si/Al = 48 and 750). The formation of intermediate species induced by the diffusion constraints for m-xylene in 10-ring channels was rationalized in the terms of the methylbenzenium ions formation inside the rigid micropore environment. Finally, both microporous character of zeolite and the optimised acidity were found to be crucial for high selectivity to the most desired product i.e. p-xylene. The analysis of asynchronous maps allowed for concluding on the order of the appearance of the respective products on the zeolite surface.

UTILITY OF ZEOLITES IN REMOVAL OF INORGANIC AND ORGANIC WATER POLLUTANTS

EPA Science Inventory

Zeolites are well known for their ion exchange, adsorption and acid catalysis properties. Different inorganic and organic pollutants have been removed from water at room temperature using various zeolites. Synthetic zeolite Faujasite Y has been used to remove inorganic pollutants...

Synthesis of mesoporous zeolite single crystals with cheap porogens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao Haixiang; Li Changlin; Ren Jiawen

2011-07-15

Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals have been successfully synthesized by adding soluble starch or sodium carboxymethyl cellulose (CMC) to a conventional zeolite synthesis system. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption analysis, {sup 27}Al magic angle spinning nuclear magnetic resonance ({sup 27}Al MAS NMR), temperature-programmed desorption of ammonia (NH{sub 3}-TPD) and ultraviolet-visible spectroscopy (UV-vis). The SEM images clearly show that all zeolite crystals possess the similar morphology with particle size of about 300 nm, the TEM images reveal that irregular intracrystalmore » pores are randomly distributed in the whole crystal. {sup 27}Al MAS NMR spectra indicate that nearly all of the Al atoms are in tetrahedral co-ordination in ZSM-5, UV-vis spectra confirm that nearly all of titanium atoms are incorporated into the framework of TS-1. The catalytic activity of meso-ZSM-5 in acetalization of cyclohexanone and meso-TS-1 in hydroxylation of phenol was also studied. The synthesis method reported in this paper is cost-effective and environmental friendly, can be easily expended to prepare other hierarchical structured zeolites. - Graphical abstract: Mesoporous zeolite single crystals were synthesized by using cheap porogens as template. Highlights: > Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals were synthesized. > Soluble starch or sodium carboxymethyl cellulose (CMC) was used as porogens. > The mesoporous zeolites had connected mesopores although closed pores existed. > Higher catalytic activities were obtained.« less

Closure of the patent ductus arteriosus with the Amplatzer Duct Occluder II: a clinical experience.

PubMed

Karagöz, Tevfik; Akin, Alper; Ertuğrul, Ilker; Aykan, Hayrettin Hakan; Alehan, Dursun; Ozer, Sema; Ozkutlu, Süheyla

2012-12-01

The aim of our study was to share our clinical experience on cases with patent ductus arteriosus treated with the Amplatzer Duct Occluder II. Between 2008 and 2012, 26 of 31 patients with patent ductus arteriosus underwent successful transcatheter closure of patent ductus arteriosus using the Amplatzer Duct Occluder II. Mean age was 3.3 years and mean weight was 15.7 kilograms. The presence of a residual shunt, left pulmonary artery or aortic obstruction was explored by administering contrast material during the procedure. The patients were discharged 24 hours after the procedure. The procedure was successful in 26 of 31 patients and failed in five patients. According to the Krichenko classification, 26 patients had type A, one patient had type B and 4 patients had type C ductus. The mean narrowest ductus diameter was 3.2 mm and the mean ductus length was 6.7 mm. Complete angiographic occlusion occurred immediately after the procedure in 22 out of 26 patients in whom the ductus was closed successfully with the Amplatzer Duct Occluder II. Complete occlusion was achieved in the remaining patients with residual shunt one month after the procedure. The procedure was preceded by closure with an Amplatzer Duct Occluder I in two patients and an Amplatzer Vascular Plug I in one patient. Amplatzer Duct Occluder II is highly effective in transcatheter closure of patent ductus arteriosus. We think that an alternative closure device and alternative techniques can be attempted in patients with type C ductus. The success rate could increase with accumulating experience.

Deposition of zeolite nanoparticles onto porous silica monolith

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gackowski, Mariusz; Bielanska, Elzbieta; Szczepanowicz, Krzysztof

2016-06-01

A facile and effective method of deposition of MFl zeolite nanoparticles (nanocrystals) onto macro-/mesoporous silica monolith was proposed. The electrostatic interaction between those two materials was induces by adsorption of cationic polyelectrolytes. That can be realized either by adsorption of polyelectrolyte onto silica monolith or on zeolite nanocrystals. The effect of time, concentration of zeolite nanocrystals, type of polyelectrolyte, and ultrasound treatment is scrutinized. Adsorption of polyelectrolyte onto silica monolith with subsequent deposition of nanocrystals resulted in a monolayer coverage assessed with SEM images. Infrared spectroscopy was applied as a useful method to determine the deposition effectiveness of zeolite nanocrystalsmore » onto silica. Modification of nanocrystals with polyelectrolyte resulted in a multilayer coverage due to agglomeration of particles. On the other hand, the excess of polyelectrolyte in the system resulted in a low coverage due to competition between polyelectrolyte and modified nanocrystals.« less

Preparation of a Versatile Bifunctional Zeolite for Targeted Imaging Applications

PubMed Central

Ndiege, Nicholas; Raidoo, Renugan; Schultz, Michael K.; Larsen, Sarah

2011-01-01

Bifunctional zeolite Y was prepared for use in targeted in vivo molecular imaging applications. The strategy involved functionalization of the external surface of zeolite Y with chloropropyltriethoxysilane followed by reaction with sodium azide to form azide-functionalized NaY, which is amenable to copper(1) catalyzed click chemistry. In this study, a model alkyne (4-pentyn-1-ol) was attached to the azide-terminated surface via click chemistry to demonstrate feasibility for attachment of molecular targeting vectors (e.g., peptides, aptamers) to the zeolite surface. The modified particle efficiently incorporates the imaging radioisotope gallium-68 (68Ga) into the pores of the azide-functionalized NaY zeolite to form a stable bifunctional molecular targeting vector. The result is a versatile “clickable” zeolite platform that can be tailored for future in vivo molecular targeting and imaging modalities. PMID:21306141

Synthesis of Zeolite-X from Bottom Ash for H2 Adsorption

NASA Astrophysics Data System (ADS)

Kurniawan, R. Y.; Romadiansyah, T. Q.; Tsamarah, A. D.; Widiastuti, N.

2018-01-01

Zeolite-X was synthesized from bottom ash power plant waste using fusion method on air atmosphere. The fused product dissolved in demineralized water and aluminate solution was added to adjust the SiO2/Al2O3 molar ratio gel prior hydrothermal process. The synthesis results were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Fourier Transform Infrared (FTIR). The results showed that the zeolite-X has a high crystallinity with octahedral particle. The pure-form zeolite-X then was characterized and tested for H2 gas adsorption by gravimetric method to determine the H2 gas adsorption capacity of zeolite-X from bottom ash and it was compared to synthetic zeolite-X.

Transcatheter Closure of Bilateral Multiple Huge Pulmonary Arteriovenous Malformations with Homemade Double-Umbrella Occluders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong Hongshan, E-mail: zhonghongshan@hotmail.com; Xu Ke; Shao Haibo

2008-07-15

A 28-year-old man underwent successful transcatheter occlusion of three huge pulmonary arteriovenous malformations (PAVMs) using homemade double-umbrella occluders and stainless steel coils. Thoracic CT with three-dimensional reconstruction and pulmonary angiography were used for treatment planning and follow-up. The diameters of the feeding vessels were 11 mm, 13 mm, and 14 mm, respectively. This report demonstrates the novel design and utility of the double-umbrella occluder, an alternative tool for treatment of large PAVMs.

Recanalisation of Chronically Occluded Remote Superficial Femoral Artery Endarterectomy Through Angioplasty for Limb Salvage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husainy, Mohammad Ali, E-mail: m.husainy@nhs.net; Slim, Hani; Rashid, Hisham

2017-02-15

We report a novel application of balloon angioplasty to recanalise a chronically occluded remote endarterectomy superficial femoral artery. This patient previously had two occluded surgical bypass grafts in an attempt to revascularise the limb and presented with critical limb ischaemia and necrotic foot ulcerations. Following the angioplasty, the patient showed significant improvement in rest pain and healing of the ulcerations. This technique may be useful for limb salvage in patients where surgical options have been exhausted.

Safety and efficacy of nano lamellar TiN coatings on nitinol atrial septal defect occluders in vivo.

PubMed

Zhang, Zhi xiong; Fu, Bu fang; Zhang, De yuan; Zhang, Zhi wei; Cheng, Yan; Sheng, Li yuan; Lai, Chen; Xi, Ting fei

2013-04-01

Atrial septal defect (ASD) occlusion devices made of nickel-titanium (NiTi) have a major shortcoming in that they release nickel into the body. We modified NiTi occluders using Arc Ion Plating technology. Nano lamellar titanium-nitrogen (TiN) coatings were formed on the surfaces of the occluders. The safety and efficacy of the modified NiTi occluders were evaluated in animal model. The results showed that 38 out of 39 rams (97%) survived at the end of the experiment. Fibrous capsules formed on the surfaces of the devices. Gradual endothelialization took place through the attachment of endothelial progenitor cells from the blood and the migration of endothelial cells from adjacent endocardium. The neo-endocardium formed more quickly in the coated group than in the uncoated group, as indicated by the evaluation of the six month study group. After TiN coating, there was no significant difference in endothelial cell cycle. TiN coating significantly reduced the release of nickel in both in vivo and in vitro indicating an improved biocompatibility of the nitinol ASD occluders. Superior and modified ASD occluders may provide a good choice for people with nickel allergies after sFDA registration, which is expected in one to two years. Copyright © 2012 Elsevier B.V. All rights reserved.

Large zeolites - Why and how to grow in space

NASA Technical Reports Server (NTRS)

Sacco, Albert, Jr.

1991-01-01

The growth of zeolite crystals which are considered to be the most valuable catalytic and adsorbent materials of the chemical processing industry are discussed. It is proposed to use triethanolamine as a nucleation control agent to control the time release of Al in a zeolite A solution and to increase the average and maximum crystal size by 25-50 times. Large zeolites could be utilized to make membranes for reactors/separators which will substantially increase their efficiency.

Antimicrobial Activity of Silver Ions Released from Zeolites Immobilized on Cellulose Nanofiber Mats.

PubMed

Rieger, Katrina A; Cho, Hong Je; Yeung, Hiu Fai; Fan, Wei; Schiffman, Jessica D

2016-02-10

In this study, we exploit the high silver ion exchange capability of Linde Type A (LTA) zeolites and present, for the first time, electrospun nanofiber mats decorated with in-house synthesized silver (Ag(+)) ion exchanged zeolites that function as molecular delivery vehicles. LTA-Large zeolites with a particle size of 6.0 μm were grown on the surface of the cellulose nanofiber mats, whereas LTA-Small zeolites (0.2 μm) and three-dimensionally ordered mesoporous-imprinted (LTA-Meso) zeolites (0.5 μm) were attached to the surface of the cellulose nanofiber mats postsynthesis. After the three zeolite/nanofiber mat assemblies were ion-exchanged with Ag(+) ions, their ion release profiles and ability to inactivate Escherichia coli (E. coli) K12 were evaluated as a function of time. LTA-Large zeolites immobilized on the nanofiber mats displayed more than an 11 times greater E. coli K12 inactivation than the Ag-LTA-Large zeolites that were not immobilized on the nanofiber mats. This study demonstrates that by decorating nanometer to micrometer scale Ag(+) ion-exchanged zeolites on the surface of high porosity, hydrophilic cellulose nanofiber mats, we can achieve a tunable release of Ag(+) ions that inactivate bacteria faster and are more practical to use in applications over powder zeolites.

Cardi-O-Fix duct occluder versus Amplatzer duct occluder for closure of patent ductus arteriosus.

PubMed

Celebi, Ahmet; Demir, Ibrahim Halil; Saritaş, Türkay; Dedeoğlu, Reyhan; Yucel, Ilker Kemal; Demir, Fadli; Erdem, Abdullah

2013-11-15

We sought to investigate the safety, efficacy, and follow-up results of percutaneous patent ductus arteriosus (PDA) closure using the novel Cardi-O-Fix duct occluder (CDO), a device similar to but less expensive than the Amplatzer duct occluder (ADO). We also aimed to compare these two devices in terms of results. Between March 2005 and May 2012, 167 patients diagnosed with moderate-to-large PDA underwent transcatheter closure. ADO was used in 56 (33.5%) patients with a mean age of 8.1 ± 11.9 years (3.6 months-56 years), whereas CDO was used in 111 (66.5%) patients with a mean age of 12.6 ± 14.6 years (4.8 months-63 years). The narrowest PDA diameter, the used device diameter, procedure time, fluoroscopy time, and residual shunt rates were similar between the two groups. Procedural success rate was 100% in both groups. Although the residual shunt rate was higher in the CDO group immediately after the procedure, the difference was not statistically significant (12.6 vs. 8.9%; P = 0.3). There was no statistically significant difference between groups at discharge and during follow-up. No deaths occurred in any of the groups, and there were no differences in complication rates during the short- and mid-term follow-up periods (CDO 7/111 vs. ADO 5/56; P = 0.5 π). The CDO can be used for PDA closure because of its safety, effectiveness, and simplicity in use. It is available in bigger sizes and can be used in patients with large defects. According to our short- and mid-term findings, the results it yields are similar to those of the ADO; thus, it may be the preferred choice owing to its low cost and large size variability. Copyright © 2013 Wiley Periodicals, Inc.

Theoretical studies of alkyl radicals in the NaY and HY zeolites.

PubMed

Ghandi, Khashayar; Zahariev, Federico E; Wang, Yan Alexander

2005-08-18

Interplay of quantum mechanical calculations and experimental data on hyperfine coupling constants of ethyl radical in zeolites at several temperatures was engaged to study the geometries and binding energies and to predict the temperature dependence of hyperfine splitting of a series of alkyl radicals in zeolites for the first time. The main focus is on the hyperfine interaction of alkyl radicals in the NaY and HY zeolites. The hyperfine splitting for neutral free radicals and free radical cations is predicted for different zeolite environments. This information can be used to establish the nature of the muoniated alkyl radicals in the NaY and HY zeolites via muSR experiments. The muon hyperfine coupling constants of the ethane radical cation in these zeolites are very large with relatively little dependence on temperature. It was found that the intramolecular dynamics of alkyl free radicals are only weakly affected by their strong binding to zeolites. In contrast, the substrate binding has a significant effect on their intermolecular dynamics.

Fabrication of silver nanoparticles doped in the zeolite framework and antibacterial activity.

PubMed

Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa

2011-01-01

Using the chemical reduction method, silver nanoparticles (Ag NPs) were effectively synthesized into the zeolite framework in the absence of any heat treatment. Zeolite, silver nitrate, and sodium borohydride were used as an inorganic solid support, a silver precursor, and a chemical reduction agent, respectively. Silver ions were introduced into the porous zeolite lattice by an ion-exchange path. After the reduction process, Ag NPs formed in the zeolite framework, with a mean diameter of about 2.12-3.11 nm. The most favorable experimental condition for the synthesis of Ag/zeolite nanocomposites (NCs) is described in terms of the initial concentration of AgNO(3). The Ag/zeolite NCs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, and Fourier transform infrared. The results show that Ag NPs form a spherical shape with uniform homogeneity in the particle size. The antibacterial activity of Ag NPs in zeolites was investigated against Gram-negative bacteria (ie, Escherichia coli and Shigella dysentriae) and Gram-positive bacteria (ie, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus) by disk diffusion method using Mueller-Hinton agar at different sizes of Ag NPs. All of the synthesized Ag/zeolite NCs were found to have antibacterial activity. These results show that Ag NPs in the zeolite framework can be useful in different biological research and biomedical applications.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayoub, Muhammad, E-mail: muhammad.ayoub@petronas.com.my; Abdullah, Ahmad Zuhairi, E-mail: chzuhairi@usm.my; Inayat, Abrar, E-mail: abrar.inayat@petronas.com.my

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 ofmore » zeolite was sustained after lithium modification. The surface properties of parent and modified zeolite was also observed N{sub 2} 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.« less

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.

Antibacterial properties of Ag-exchanged Philippine natural zeolite-chitosan composites

NASA Astrophysics Data System (ADS)

Taaca, Kathrina Lois M.; Olegario, Eleanor M.; Vasquez, Magdaleno R.

2017-12-01

Zeolites are microporous minerals composed of silicon, aluminum and oxygen. These aluminosilicates consist of tetrahedral units which produce open framework structures to generate a system of pores and cavities of molecular dimensions. Zeolites are naturally abundant and can be mined in most parts of the world. In this study, natural zeolites (NaZ) which are locally-sourced here in the Philippines were investigated to determine its properties. An ion-exchange process was utilized, using the zeolite to silver (Ag) solution ratio of 1:20 (w/v), to incorporate Ag into the zeolite framework. Characterizations such as XRD, AAS, and Agar diffusion assay were used to evaluate the properties of the synthesized Ag-exchanged zeolites (AgZ). X-ray diffraction revealed that both NaZ and AgZ have peaks mostly corresponding to the clinoptilolite structure, with some trace peaks of the mordenite and quartz. Absorption spectroscopy revealed that the ion exchange process added about 0.61188g of silver into the zeolite structure. This Ag content was seen to be enough to make the AgZ sample exhibit an antibacterial effect where clearing zones against E. coli and S. aureus were observed in the agar diffusion assay, respectively. The AgZ sample was also tested as ceramic filler to a polymer matrix-chitosan. The diffusion assay revealed presence of antibacterial activity to the polymer composite with AgZ fillers. These results indicate that the Philippine natural zeolite, incorporated with metals such as Ag, can be used as an antibacterial agent and can be developed as a ceramic filler to improve the antibacterial property of composite materials for biomedical application.

Fly ash based zeolitic pigments for application in anticorrosive paints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, Ruchi, E-mail: shawruchi1@gmail.com; Tiwari, Sangeeta, E-mail: stiwari2@amity.edu

2016-04-13

The purpose of this work is to evaluate the utilization of waste fly ash in anticorrosive paints. Zeolite NaY was synthesized from waste fly ash and subsequently modified by exchanging its nominal cation Na{sup +} with Mg{sup 2+} and Ca{sup 2+} ions. The metal ion exchanged zeolite was then used as anticorrosive zeolitic pigments in paints. The prepared zeolite NaY was characterized using X-Ray diffraction technique and Scanning electron microscopy. The size, shape and density of the prepared fly ash based pigments were determined by various techniques. The paints were prepared by using fly ash based zeolitic pigments in epoxymore » resin and the percentages of pigments used in paints were 2% and 5%. These paints were applied to the mild steel panels and the anticorrosive properties of the pigments were assessed by the electrochemical spectroscopy technique (EIS).« less

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.

Sulfur tolerant zeolite supported platinum catalysts for aromatics hydrogenation

DOT National Transportation Integrated Search

1997-04-01

An experimental study of sulfur tolerant zeolite platinum catalysts for aormatics hydrogenation. Platinum catalysts supported on Y-zeolite have been prepared and characterized in various ways, including the hydrogenation of toluene in a high pressure...

Recommended nomenclature for zeolite minerals: Report of the Subcommittee on Zeolites of the International Mineralogical Association, Commission on 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 on New Minerals and Mineral Names. In a working definition of a zeolite mineral used for this review, structures containing an interrupted containing an interrupted framework of tetrahedra are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is alloowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundant 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 in 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 zeolite. Newly recognized species in compositional series are as follows: brewsterite-Sr, -Ba; chabazite-Ca, -Na, -K; clinoptilolite-K, -Na, -Ca; dechiardite-Ca, -Na; erionite-Na, -K, -Ca,; faujasite-Na, -Ca, -Mg; ferrierite-Mg, -K, -Na; gmelinite-Na, -Ca, -K; heulandite-Ca, -Na, -K, -Sr; levyne-Ca, -Na; paulingite-K, -Ca; phillipsite-Na, -Ca, -K 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

Recommended nomenclature for zeolite minerals: report of the subcommittee on zeolites of the International Mineralogical Association, Commission on 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.

1997-01-01

This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association, Commission on New Minerals and Mineral Names. In a working definition of a zeolite mineral used for this review, structures containing an interrupted framework of tetrahedra 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 abundant in atomic proportions. To name these, the appropriate chemicalsymbol 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 the ratio Si:Al except for heulandite (Si:Al < 4.0) and clinoptilolite (Si:Al ??? 4.0). Dehydration, partial hydration, and overhydration 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-Na, erionite-Na, -K, -Ca, faujasite-Na, -Ca, -Mg, ferrierite-Mg, -K, -Na, gmelinite-Na, -Ca, -K, heulandite-Ca, -Na, -K, -Sr, levyne-Ca, -Na, paulingite-K, -Ca, phillipsite-Na, -Ca, -K, and 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

ZEOLITE PERFORMANCE AS AN ANION EXCHANGER FOR ARSENIC SEQUESTRATION IN WATER

EPA Science Inventory

Zeolites are well known for their use in ion exchange and acid catalysis reactions. The use of zeolites in anion or ligand exchange reactions is less studied. The NH4+ form of zeolite Y (NY6, Faujasite) has been tested in this work to evaluate its performance for arsenic removal...

Synthetic Zeolites as Controlled-Release Delivery Systems for Anti-Inflammatory Drugs.

PubMed

Khodaverdi, Elham; Soleimani, Hossein Ali; Mohammadpour, Fatemeh; Hadizadeh, Farzin

2016-06-01

Scientists have always been trying to use artificial zeolites to make modified-release drug delivery systems in the gastrointestinal tract. An ideal carrier should have the capability to release the drug in the intestine, which is the main area of absorption. Zeolites are mineral aluminosilicate compounds with regular structure and huge porosity, which are available in natural and artificial forms. In this study, soaking, filtration and solvent evaporation methods were used to load the drugs after activation of the zeolites. Weight measurement, spectroscopy FTIR, thermogravimetry and scanning electronic microscope were used to determine drug loading on the systems. Finally, consideration of drug release was made in a simulated gastric fluid and a simulated intestinal fluid for all matrixes (zeolites containing drugs) and drugs without zeolites. Diclofenac sodium (D) and piroxicam (P) were used as the drug models, and zeolites X and Y as the carriers. Drug loading percentage showed that over 90% of drugs were loaded on zeolites. Dissolution tests in stomach pH environment showed that the control samples (drug without zeolite) released considerable amount of drugs (about 90%) within first 15 min when it was about 10-20% for the matrixes. These results are favorable as NSAIDs irritate the stomach wall and it is ideal not to release much drugs in the stomach. Furthermore, release rate of drugs from matrixes has shown slower rate in comparison with control samples in intestine pH environment. © 2016 John Wiley & Sons A/S.

Fabrication of silver nanoparticles doped in the zeolite framework and antibacterial activity

PubMed Central

Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa

2011-01-01

Using the chemical reduction method, silver nanoparticles (Ag NPs) were effectively synthesized into the zeolite framework in the absence of any heat treatment. Zeolite, silver nitrate, and sodium borohydride were used as an inorganic solid support, a silver precursor, and a chemical reduction agent, respectively. Silver ions were introduced into the porous zeolite lattice by an ion-exchange path. After the reduction process, Ag NPs formed in the zeolite framework, with a mean diameter of about 2.12–3.11 nm. The most favorable experimental condition for the synthesis of Ag/zeolite nanocomposites (NCs) is described in terms of the initial concentration of AgNO3. The Ag/zeolite NCs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, and Fourier transform infrared. The results show that Ag NPs form a spherical shape with uniform homogeneity in the particle size. The antibacterial activity of Ag NPs in zeolites was investigated against Gram-negative bacteria (ie, Escherichia coli and Shigella dysentriae) and Gram-positive bacteria (ie, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus) by disk diffusion method using Mueller–Hinton agar at different sizes of Ag NPs. All of the synthesized Ag/zeolite NCs were found to have antibacterial activity. These results show that Ag NPs in the zeolite framework can be useful in different biological research and biomedical applications. PMID:21383858

Translation in cardiovascular stents and occluders: From biostable to fully degradable

PubMed Central

Huang, Yingying; Wong, Yee Shan; Ng, Herr Cheun Anthony; Boey, Freddy Y. C.

2017-01-01

Abstract Cardiovascular disease is a major cause of morbidity and mortality, especially in developed countries. Most academic research efforts in cardiovascular disease management focus on pharmacological interventions, or are concerned with discovering new disease markers for diagnosis and monitoring. Nonpharmacological interventions with therapeutic devices, conversely, are driven largely by novel materials and device design. Examples of such devices include coronary stents, heart valves, ventricular assist devices, and occluders for septal defects. Until recently, development of such devices remained largely with medical device companies. We trace the materials evolution story in two of these devices (stents and occluders), while also highlighting academic contributions, including our own, to the evolution story. Specifically, it addresses not only our successes, but also the challenges facing the translatability of concepts generated via academic research. PMID:29313029

Performance evaluation of two protective treatments on salt-laden limestones and marble after natural and artificial weathering.

PubMed

Salvadori, Barbara; Pinna, Daniela; Porcinai, Simone

2014-02-01

Salt crystallization is a major damage factor in stone weathering, and the application of inappropriate protective products may amplify its effects. This research focuses on the evaluation of two protective products' performance (organic polydimethylsiloxane and inorganic ammonium oxalate (NH4)2(COO)2·H2O) in the case of a salt load from behind. Experimental laboratory simulations based on salt crystallization cycles and natural weathering in an urban area were carried out. The effects were monitored over time, applying different methods: weight loss evaluation, colorimetric and water absorption by capillarity measurements, stereomicroscope observations, FTIR and SEM-EDS analyses. The results showed minor impact exerted on the short term on stones, particularly those treated with the water repellent, by atmospheric agents compared to salt crystallization. Lithotypes with low salt load (Gioia marble) underwent minor changes than the heavily salt-laden limestones (Lecce and Ançã stones), which were dramatically damaged when treated with polysiloxane. The results suggest that the ammonium oxalate treatment should be preferred to polysiloxane in the presence of soluble salts, even after desalination procedures which might not completely remove them. In addition, the neo-formed calcium oxalate seemed to effectively protect the stone, improving its resistance against salt crystallization without occluding the pores and limiting the superficial erosion caused by atmospheric agents.

Nano-sized zeolites as modulators of thiacloprid toxicity on Chironomus riparius

PubMed Central

Wicht, Anna-Jorina; Guluzada, Leyla; Crone, Barbara; Karst, Uwe; Lee, Hwa Jun; Triebskorn, Rita; Haderlein, Stefan B.; Huhn, Carolin; Köhler, Heinz-R.

2017-01-01

This study investigated whether zeolites of different size (Y30 (nano-sized) and H-Beta(OH)-III (forming large aggregates/agglomerates composed of 50 nm small primary particles)) exerted acute toxicity on larvae of the non-biting midge, Chironomus riparius, and whether such zeolites are able to modulate the toxicity of a common insecticide, thiacloprid, by means of adsorption of a dissolved toxicant. We conducted acute toxicity tests with fourth instar larvae of C. riparius. In these tests, larvae were exposed to zeolites or thiacloprid solely, or to mixtures of both compounds. The mixtures comprised 1.0 µg/L thiacloprid in addition to low (5.2 mg/L), medium (18.2 mg/L), and high (391.7 mg/L) zeolite concentrations, resulting in different adsorption rates of thiacloprid. As biological endpoints, changes in mortality rates and in behavior were monitored every 24 h over a total investigation period of 96 h. Furthermore, we conducted chemical analyses of thiacloprid in the medium and the larvae and located the zeolite particles within the larvae by LA-ICP-MS imaging techniques. Our results demonstrate that both types of zeolites did not exert acute toxicity when applied as single-substances, but led to reduced acute toxicity of thiacloprid when applied together with thiacloprid. These results are in line with the sorption properties of zeolites indicating reduced bioavailability of thiacloprid, although our data indicate that thiacloprid can desorb from zeolites to some extent. While freely dissolved (i.e., non-sorbed) fraction of thiacloprid was a good parameter to roughly estimate toxic effects, it did not correlate with measured internal thiacloprid concentrations. Moreover, it was shown that both zeolite types were ingested by the larvae, but no indication for cellular uptake of them was found. PMID:28729952

Nanoscale Chemical Imaging of Zeolites Using Atom Probe Tomography.

PubMed

Weckhuysen, Bert Marc; Schmidt, Joel; Peng, Linqing; Poplawsky, Jonathan

2018-05-02

Understanding structure-composition-property relationships in zeolite-based materials is critical to engineering improved solid catalysts. However, this can be difficult to realize as even single zeolite crystals can exhibit heterogeneities spanning several orders of magnitude, with consequences for e.g. reactivity, diffusion as well as stability. Great progress has been made in characterizing these porous solids using tomographic techniques, though each method has an ultimate spatial resolution limitation. Atom Probe Tomography (APT) is the only technique so far capable of producing 3-D compositional reconstructions with sub-nm-scale resolution, and has only recently been applied to zeolite-based catalysts. Herein, we discuss the use of APT to study zeolites, including the critical aspects of sample preparation, data collection, assignment of mass spectral peaks including the predominant CO peak, the limitations of spatial resolution for the recovery of crystallographic information, and proper data analysis. All sections are illustrated with examples from recent literature, as well as previously unpublished data and analyses to demonstrate practical strategies to overcome potential pitfalls in applying APT to zeolites, thereby highlighting new insights gained from the APT method. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Computational evaluation of aortic occlusion and the proposal of a novel, improved occluder: Constrained endo-aortic balloon occlusion.

PubMed

de Vaal, M H; Gee, M W; Stock, U A; Wall, W A

2016-12-01

Because aortic occlusion is arguably one of the most dangerous aortic manipulation maneuvers during cardiac surgery in terms of perioperative ischemic neurological injury, the purpose of this investigation is to assess the structural mechanical impact resulting from the use of existing and newly proposed occluders. Existing (clinically used) occluders considered include different cross-clamps (CCs) and endo-aortic balloon occlusion (EABO). A novel occluder is also introduced, namely, constrained EABO (CEABO), which consists of applying a constrainer externally around the aorta when performing EABO. Computational solid mechanics are employed to investigate each occluder according to a comprehensive list of functional requirements. The potential of a state of occlusion is also considered for the first time. Three different constrainer designs are evaluated for CEABO. Although the CCs were responsible for the highest strains, largest deformation, and most inefficient increase of the occlusion potential, it remains the most stable, simplest, and cheapest occluder. The different CC hinge geometries resulted in poorer performance of CC used for minimally invasive procedures than conventional ones. CEABO with a profiled constrainer successfully addresses the EABO shortcomings of safety, stability, and positioning accuracy, while maintaining its complexities of operation (disadvantage) and yielding additional functionalities (advantage). Moreover, CEABO is able to achieve the previously unattainable potential to provide a clinically determinable state of occlusion. CEABO offers an attractive alternative to the shortcomings of existing occluders, with its design rooted in achieving the highest patient safety. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The Influence of Zeolites on Radical Formation During Lignin Pyrolysis.

PubMed

Bährle, Christian; Custodis, Victoria; Jeschke, Gunnar; van Bokhoven, Jeroen A; Vogel, Frédéric

2016-09-08

Lignin from lignocellulosic biomass is a promising source of energy, fuels, and chemicals. The conversion of the polymeric lignin to fuels and chemicals can be achieved by catalytic and noncatalytic pyrolysis. The influence of nonporous silica and zeolite catalysts, such as silicalite, HZSM5, and HUSY, on the radical and volatile product formation during lignin pyrolysis was studied by in situ high-temperature electron paramagnetic resonance spectroscopy (HTEPR) as well as GC-MS. Higher radical concentrations were observed in the samples containing zeolite compared to the sample containing only lignin, which suggests that there is a stabilizing effect by the inorganic surfaces on the formed radical fragments. This effect was observed for nonporous silica as well as for HUSY, HZSM5, and silicalite zeolite catalysts. However, the effect is far larger for the zeolites owing to their higher specific surface area. The zeolites also showed an effect on the volatile product yield and the product distribution within the volatile phase. Although silicalite showed no effect on the product selectivity, the acidic zeolites such as HZSM5 or HUSY increased the formation of deoxygenated products such as benzene, toluene, xylene (BTX), and naphthalene. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Annealing Temperature on Broad Luminescence of Silver-Exchanged Zeolites Y and A

NASA Astrophysics Data System (ADS)

Gui, Sa Chu Rong; Lin, H.; Bao, W.; Wang, W.

2018-05-01

The annealing temperature dependence of luminescence properties of silver (Ag)-exchanged zeolites Y and A was studied. It was found that the absorbance and excitation/emission bands are strongly affected by the thermal treatments. With increase in annealing temperature, the absorbance of Ag in zeolite Y increases at first and then decreases. However, the position of the excitation/emission band in zeolite Y was found to be insensitive to the annealing temperature. In contrast, the excitation/emission bands in zeolite A are particularly sensitive to the annealing temperature. The difference of such temperature dependence in zeolites Y and A may be due to the different microporous structure of the two minerals. Moreover, the fact that this dependence is not observed in Ag-exchanged zeolite Y is likely to be due to the difficulty in dehydration of zeolite Y in air or due to the weak Ag+-Ag+ interaction in zeolite Y.

European Microgravity Facilities for ZEOLITE Experiments on the International Space Station

NASA Astrophysics Data System (ADS)

Pletser, V.; Minster, O.; Kremer, S.; Kirschhock, C.; Martens, J.; Jacobs, P.

2002-01-01

Synthetic zeolites are complex porous silicates. Zeolites are applied as catalysts, adsorbents and sensors. Whereas the traditional applications are situated in the petrochemical area, zeolite catalysis and related zeolite-based technologies have a growing impact on the economics and sustainability of products and processes in a growing number of industrial sectors, including environmental protection and nanotechnology. A Sounding Rocket microgravity experiment led to significant insight in the physical aggregation patterns of zeolitic nanoscopic particles and the occurrence of self-organisation phenomena when undisturbed by convection. The opportunity of performing longer microgravity duration experiments on zeolite structures was recently offered in the frame of a Taxi-Flight to the ISS in November 2002 organized by Belgium and ESA. Two facilities are currently under development for this flight. One of them will use the Microgravity Science Glovebox (MSG) in the US Lab. Destiny to achieve thermal induced self-organization of different types of Zeosil nanoslabs by heating and cooling. The other facility will be flown on the ISS Russian segment and will allow to form Zeogrids at ambient temperature. On the other hand, the European Space Agency (ESA) is studying the possibility of developing a dedicated insert for zeolite experiments to be used with the optical and diagnostic platform of the Protein Crystallisation Diagnostic Facility (PCDF), that will fly integrated in the European Drawer Rack on the Columbus Laboratory starting in 2004. This paper will present the approach followed by ESA to prepare and support zeolite investigations in microgravity and will present the design concept of these three facilities.

Externalized decondensed neutrophil chromatin occludes pancreatic ducts and drives pancreatitis

PubMed Central

Leppkes, Moritz; Maueröder, Christian; Hirth, Sebastian; Nowecki, Stefanie; Günther, Claudia; Billmeier, Ulrike; Paulus, Susanne; Biermann, Mona; Munoz, Luis E.; Hoffmann, Markus; Wildner, Dane; Croxford, Andrew L.; Waisman, Ari; Mowen, Kerri; Jenne, Dieter E.; Krenn, Veit; Mayerle, Julia; Lerch, Markus M.; Schett, Georg; Wirtz, Stefan; Neurath, Markus F.; Herrmann, Martin; Becker, Christoph

2016-01-01

Ductal occlusion has been postulated to precipitate focal pancreatic inflammation, while the nature of the primary occluding agents has remained elusive. Neutrophils make use of histone citrullination by peptidyl arginine deiminase-4 (PADI4) in contact to particulate agents to extrude decondensed chromatin as neutrophil extracellular traps (NETs). In high cellular density, NETs form macroscopically visible aggregates. Here we show that such aggregates form inside pancreatic ducts in humans and mice occluding pancreatic ducts and thereby driving pancreatic inflammation. Experimental models indicate that PADI4 is critical for intraductal aggregate formation and that PADI4-deficiency abrogates disease progression. Mechanistically, we identify the pancreatic juice as a strong instigator of neutrophil chromatin extrusion. Characteristic single components of pancreatic juice, such as bicarbonate ions and calcium carbonate crystals, induce aggregated NET formation. Ductal occlusion by aggregated NETs emerges as a pathomechanism with relevance in a plethora of inflammatory conditions involving secretory ducts. PMID:26964500

Zeolitic catalytic conversion of alochols to hydrocarbons

DOEpatents

Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

2017-01-03

A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

Zeolitic catalytic conversion of alcohols to hydrocarbons

DOEpatents

Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

2018-04-10

A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

Molecular interactions of alcohols with zeolite BEA and MOR frameworks.

PubMed

Stückenschneider, Kai; Merz, Juliane; Schembecker, Gerhard

2013-12-01

Zeolites can adsorb small organic molecules such as alcohols from a fermentation broth. Also in the zeolite-catalyzed conversion of alcohols to biofuels, biochemicals, or gasoline, adsorption is the first step. Several studies have investigated the adsorption of alcohols in different zeolites experimentally, but computational investigations in this field have mostly been restricted to zeolite MFI. In this study, the adsorption of C1-C4 alcohols in BEA and MOR was investigated using density functional theory (DFT). Calculated adsorption geometries and the corresponding energies of the designed cluster models were comparable to periodic calculations, and the adsorption energies were in the same range as the corresponding computational and experimental values reported in the literature for zeolite MFI. Thus, BEA and MOR may be good adsorption materials for alcohols in the field of downstream processing and catalysis. Aside from the DFT calculations, adsorption isotherms were determined experimentally in this study from aqueous solutions. For BEA, the adsorption of significant amounts of alcohol from aqueous solution was observed experimentally. In contrast, MOR was loaded with only a very small amount of alcohol. Although differences were found between the affinities obtained from gas-phase DFT calculations and those observed experimentally in aqueous solution, the computational data presented here represent molecular level information on the geometries and energies of C1-C4 alcohols adsorbed in zeolites BEA and MOR. This knowledge should prove very useful in the design of zeolite materials intended for use in adsorption and catalytic processes, as it allows adsorption behavior to be predicted via judiciously designed computational models.

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

PubMed

Vaičiukynienė, Danutė; Kantautas, Aras; Vaitkevičius, Vitoldas; Jakevičius, Leonas; Rudžionis, Žymantas; Paškevičius, Mantas

2015-11-01

The synthesis of zeolite NaA from silica by-product was carried out in the presence of 20 kHz 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. Copyright © 2015 Elsevier B.V. All rights reserved.

Measurement of cation exchange capacity (CEC) on natural zeolite by percolation method

NASA Astrophysics Data System (ADS)

Wiyantoko, Bayu; Rahmah, Nafisa

2017-12-01

The cation exchange capacity (CEC)measurement has been carried out in natural zeolite by percolation method. The natural zeolite samples used for cation exchange capacity measurement were activated beforehand with physical activation and chemical activation. The physically activated zeolite was done by calcination process at 600 °C for 4 hours. The natural zeolite was activated chemically by using sodium hydroxide by refluxing process at 60-80 °C for 3 hours. In summary, cation exchange capacity (CEC) determination was performed by percolation, distillation and titration processes. Based on the measurement that has been done, the exchange rate results from physical activated and chemical activated of natural zeolite were 181.90cmol (+)/kg and 901.49cmol (+)/kg respectively.

Facile synthesis of hollow zeolite microspheres through dissolution–recrystallization procedure in the presence of organosilanes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao, Haixiang; Ren, Jiawen; Liu, Xiaohui

2013-04-15

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. - Graphical abstract: Hollowmore » zeolite spheres with aggregated zeolite nanocrystals were synthesized via a dissolution–recrystallization procedure in the presence of organosiline. Highlights: ► Hollow zeolite spheres with aggregated zeolite nanocrystals were synthesized via a dissolution–recrystallization procedure. ► Organosilane influences both the morphology and hollow structure of zeolite spheres. ► Hollow zeolite spheres showed an excellent catalytic performance in alkylation of toluene with benzyl chloride.« less

Changing of Sumatra backswamp peat properties by seawater and zeolite application

NASA Astrophysics Data System (ADS)

Sarifuddin; Nasution, Z.; Rauf, A.; Mulyanto, B.

2018-02-01

This research attempts to improve the properties of backswamp peatsoil originated from Asahan District, North Sumatra Indonesia by adding sea water and zeolite using factorial randomized block design with volume of sea water as first factor, consisting of without seawater, 500 ml, 1000 ml and 1500 ml and second factor are dosages of zeolite consisting of without zeolite, 100 g, 200 g each 10 kgs of wet peat soil. at green house in faculty of agriculture University of Sumatra Utara (USU) Medan, Indonesia. The result showed that the application of seawater decreased pH, C/N and Cation Exchange Capacity and increased of base saturation of peat soil. Adding of zeolite minerals can buffered the increasing of acidity and Electric Conductivity caused by sea water application. Interaction seawater + zeolite decreased of C/N and increased of percent of base saturation.

ZEOLITE: "THE MAGIC STONE"; MAIN NUTRITIONAL, ENVIRONMENTAL, EXPERIMENTAL AND CLINICAL FIELDS OF APPLICATION.

PubMed

Laurino, Carmen; Palmieri, Beniamino

2015-08-01

zeolites (clinoptilolites) are a family of alluminosilicates and cations clustered to form macro aggregates by small individual cavities. In the medical area they are involved in detoxification mechanisms capturing ions and molecules into their holes. Actually, we classify about 140 types of natural and 150 synthetic zeolites, for specific and selective use. Clinoptilolite is a natural zeolite and it is the most widespread compound in the medical market. this review analyzes the main fields of zeolite utilization. we searched Pubmed/Medline using the terms "zeolite" and "clinoptilolite". in zoothechnology and veterinary medicine zeolite improves the pets' fitness, removes radioactive elements, aflatoxines and poisons. Zeolite displays also antioxidant, whitening, hemostatic and anti-diarrhoic properties, projected in human care. However very scanty clinical studies have been run up to now in immunodeficiency, oncology after chemotherapy and radiotherapy as adjuvants. further clinical investigations are urgently required after this review article publication which updates the state of the art. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Thermal expansion of ceramic samples containing natural zeolite

NASA Astrophysics Data System (ADS)

Sunitrová, Ivana; Trník, Anton

2017-07-01

In this study the thermal expansion of ceramic samples made from natural zeolite is investigated. Samples are prepared from the two most commonly used materials in ceramic industry (kaolin and illite). The first material is Sedlec kaolin from Czech Republic, which contains more than 90 mass% of mineral kaolinite. The second one is an illitic clay from Tokaj area in Hungary, which contains about 80 mass% of mineral illite. Varying amount of the clay (0 % - 50 %) by a natural zeolite from Nižný Hrabovec (Slovak Republic), containing clinoptilolite as major mineral phase is replaced. The measurements are performed on cylindrical samples with a diameter 14 mm and a length about 35 mm by a horizontal push - rod dilatometer. Samples made from pure kaolin, illite and zeolite are also subjected to this analysis. The temperature regime consists from linear heating rate of 5 °C/min from 30 °C to 1100 °C. The results show that the relative shrinkage of ceramic samples increases with amount of zeolite in samples.

Modification of Natural Zeolite with Fe(III) and Its Application as Adsorbent Chloride and Carbonate ions

NASA Astrophysics Data System (ADS)

Suhartana; Sukmasari, Emmanuella; Azmiyawati, Choiril

2018-04-01

The aim of the research is to natural zeolite with Fe(III) using anion exchange process to improve the anion exchange capacity. Natural zeolite was activated using HNO3 1 N and then mixed with FeCl3 solution and refluxed followed by oven and calcination at a temperature of 550°C. The influence of Fe(III) to zeolite was characterized by FTIR while presence of Fe in zeolite characterized by AAS. Zeolite and Zeolite-Fe adsorption capacity of chloride and carbonate anions were determined through adsorption test by variation of pH and contact time. In advanced, and then to determining the Fe adsorbed concentration at Zeolite using UV-Vis spectrophotometer. FTIR analysis result showed that the addition of Fe does not affect the zeolite’s structure but change the intensity of the zeolite spectra. The Fe concentration in Zeolite-Fe of 714 mg L-1, indicate that Fe was present in the zeolite. Both Zeolite and Zeolite-Fe adsorbtion results showed that optimum pH of Chloride anion is 2, with adsorption capacity 2,33 x 10-3 gg-1 and optimum contact time is 8 minutes. While Zeolite and Zeolite-Fe adsorbtion results showed that optimum pH of Carbonate anion is 5, with adsorption capacity 5,31 x 10-3 gg-1 and optimum contact time is 8 minutes.

Ultrasmall Zeolite L Crystals Prepared from Highly-Interdispersed Alkali-Silicate Precursors.

PubMed

Li, Rui; Linares, Noemi; Sutjianto, James G; Chawla, Aseem; Garcia Martinez, Javier; Rimer, Jeffrey D

2018-06-19

The preparation of nanosized zeolites is critical for applications where mass transport limitations within microporous networks hinder their performance. Oftentimes the ability to generate ultrasmall zeolite crystals is dependent upon the use of expensive organics with limited commercial relevance. Here, we report the generation of zeolite L crystals with uniform sizes less than 30 nm using a facile, organic-free method. Time-resolved analysis of precursor assembly and evolution during nonclassical crystallization highlights key differences among silicon sources. Our findings reveal that a homogenous dispersion of potassium ions throughout silicate precursors is critical to enhancing the rate of nucleation and facilitating the formation of ultrasmall crystals. Intimate contact between the inorganic structure-directing agent and silica leads to the formation of a metastable nonporous phase, identified as KAlSi2O6, which undergoes an intercrystalline transformation to zeolite L. The presence of highly-interdispersed alkali-silicate precursors is seemingly integral to a reduced zeolite induction time and may facilitate the development of ultrasmall crystals. Given the general difficulty of achieving nanosized crystals in zeolite synthesis, it is likely that using well-dispersed precursors does not have the same effect on all framework types; however, in select cases it may provide an alternative strategy for optimizing zeolite synthesis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Patent ductus arteriosus closure using Occlutech® Duct Occluder, experience in Port Elizabeth, South Africa

PubMed Central

Pepeta, Lungile; Greyling, Adele; Nxele, Mahlubandile Fintan; Makrexeni, Zongezile Masonwabe

2017-01-01

Background: Percutaneous closure of patent ductus arteriosus (PDA) has become standard therapy. Experience with the Occlutech® Duct Occluder is limited. Methods: Data regarding ductal closure using Occlutech® Duct Occluder were reviewed and prospectively collected. Demographics, hemodynamic and angiographic characteristics, complications, and outcomes were documented. Results: From March 2013 to June 2016, 65 patients (43 females and 22 males) underwent percutaneous closure of the PDA using Occlutech® Duct Occluder. The median age of the patients was 11 months (range, 1–454 months) and the median weight was 8.5 kg (range 2.5–78 kg). The mean pulmonary artery median pressure was 27 mmHg (range, 12–100 mmHg) and the QP: Qs ratio median was 1.8 (range, 1–7.5), with a pulmonary vascular resistance mean of 2.7 WU (standard deviation [SD] ±2.1). Thirty-two patients had Krichenko Type A duct (49%); 7, Type C (11%); 4, Type D (6%); and 22, Type E (34%). The ductal size (narrowest diameter at the pulmonic end) mean was 3.5 mm (SD ± 1.9 mm). The screening time mean was 17.3 min (SD ± 11.6). Out of 63 patients with successful closure of the PDA using Occlutech® Duct Occluder, there were 15 patients with small PDAs; 25 with moderate PDAs, and 23 with large PDAs. In one patient, the device dislodged to the descending aorta, and in two patients, to the right pulmonary artery immediately following deployment, with successful percutaneous (two) and surgical (one) retrieval. Complete ductal occlusion was achieved in all 63 patients on day one. Conclusion: The Occlutech® Duct Occluder is a safe and effective device for closure of ducts in appropriately selected patients. PMID:28566820

Patent ductus arteriosus closure using Occlutech® Duct Occluder, experience in Port Elizabeth, South Africa.

PubMed

Pepeta, Lungile; Greyling, Adele; Nxele, Mahlubandile Fintan; Makrexeni, Zongezile Masonwabe

2017-01-01

Percutaneous closure of patent ductus arteriosus (PDA) has become standard therapy. Experience with the Occlutech® Duct Occluder is limited. Data regarding ductal closure using Occlutech® Duct Occluder were reviewed and prospectively collected. Demographics, hemodynamic and angiographic characteristics, complications, and outcomes were documented. From March 2013 to June 2016, 65 patients (43 females and 22 males) underwent percutaneous closure of the PDA using Occlutech® Duct Occluder. The median age of the patients was 11 months (range, 1-454 months) and the median weight was 8.5 kg (range 2.5-78 kg). The mean pulmonary artery median pressure was 27 mmHg (range, 12-100 mmHg) and the QP: Qs ratio median was 1.8 (range, 1-7.5), with a pulmonary vascular resistance mean of 2.7 WU (standard deviation [SD] ±2.1). Thirty-two patients had Krichenko Type A duct (49%); 7, Type C (11%); 4, Type D (6%); and 22, Type E (34%). The ductal size (narrowest diameter at the pulmonic end) mean was 3.5 mm (SD ± 1.9 mm). The screening time mean was 17.3 min (SD ± 11.6). Out of 63 patients with successful closure of the PDA using Occlutech® Duct Occluder, there were 15 patients with small PDAs; 25 with moderate PDAs, and 23 with large PDAs. In one patient, the device dislodged to the descending aorta, and in two patients, to the right pulmonary artery immediately following deployment, with successful percutaneous (two) and surgical (one) retrieval. Complete ductal occlusion was achieved in all 63 patients on day one. The Occlutech® Duct Occluder is a safe and effective device for closure of ducts in appropriately selected patients.

Pan-nitinol occluder and special delivery device for closure of patent ductus arteriosus: a canine-model feasibility study.

PubMed

Jiang, Hai-bin; Bai, Yuan; Zong, Gang-jun; Han, Lin; Li, Wei-ping; Lu, Yang; Qin, Yong-wen; Zhao, Xian-xian

2013-01-01

The aim of this study was to evaluate a new type of occluder for patent ductus arteriosus. Patent ductus arteriosus was established in a canine model by anastomosing a length of autologous jugular vein to the descending aorta and the left pulmonary artery in an end-to-side fashion. Transcatheter closure of each patent ductus arteriosus was performed on 10 dogs, which were then monitored for as long as 6 months with aortography, echocardiography, and histologic evaluation. Transcatheter closure with use of the novel pan-nitinol device was successful in all canine models. Postoperative echocardiography showed that the location and shape of the occluders were normal, without any residual shunting. Further histologic evaluation confirmed that the occluder surface was completely endothelialized 3 months after implantation. Transcatheter patent ductus arteriosus closure with the pan-nitinol occluder can be performed safely and successfully in a canine model and shows good biological compatibility and low mortality rates.

Shear Rheology of Suspensions of Porous Zeolite Particles in Concentrated Polymer Solutions

NASA Astrophysics Data System (ADS)

Olanrewaju, Kayode O.; Breedveld, Victor

2008-07-01

We present experimental data on the shear rheology of Ultem (polyetherimide)/NMP(l-methyl-2-pyrrolidinone) solutions with and without suspended surface-modified porous/nonporous zeolite (ZSM-5) particles. We found that the porous zeolite suspensions have relative viscosities that significantly exceed the Krieger-Dougherty predictions for hard sphere suspensions. The major origin of this discrepancy is the selective absorption of NMP solvent into the zeolite pores, which raises both the polymer concentration and the particle volume fraction, thus enhancing both the viscosity of the continuous phase Ultem/NMP polymer solution and the particle contribution to the suspension viscosity. Other factors, such as zeolite non-sphericity and specific interactions with Ultem polymer, contribute to the suspension viscosity to a lesser extent. We propose a predictive model for the viscosity of porous zeolite suspensions by incorporating an absorption parameter, α, into the Krieger-Dougherty model. We also propose independent approaches to determine α. The first one is indirect and based on zeolite density/porosity data, assuming that all pores will be filled with solvent. The other method is based on our experimental data, by comparing the viscosity data of porous versus non-porous zeolite suspensions. The different approaches are compared.

Template occluded SBA-15: An effective dissolution enhancer for poorly water-soluble drug

NASA Astrophysics Data System (ADS)

Tingming, Fu; Liwei, Guo; Kang, Le; Tianyao, Wang; Jin, Lu

2010-09-01

The aim of the present work was to improve the dissolution rate of piroxicam by inclusion into template occluded SBA-15. Our strategy involves directly introducing piroxicam into as-prepared SBA-15 occluded with P123 (EO 20PO 70EO 20) by self assembling method in acetonitrile/methylene chloride mixture solution. Ultraviolet spectrometry experiment and thermogravimetric analysis-differential scanning calorimetry (TG-DSC) profiles show that the piroxicam and P123 contents in the inclusion compound are 12 wt% and 28 wt%, respectively. X-ray powder diffraction and DSC analysis reveal that the included piroxicam is arranged in amorphous form. N 2 adsorption-desorption experiment indicates that the piroxicam has been introduced to the mesopores instead of precipitating at the outside of the silica material. The inclusion compound was submitted to in vitro dissolution tests, the results show that the piroxicam dissolve from template occluded inclusion compound more rapidly, than these from the piroxicam crystalline and template removed samples in all tested conditions. Thus a facile method to improve the dissolution rate of poorly water-soluble drug was established, and this discovery opens a new avenue for the utilization of templates used for the synthesis of mesoporous materials.

N-C isotopic investigation of a zeolite-amended agricultural field

NASA Astrophysics Data System (ADS)

Ferretti, Giacomo; Natali, Claudio; Faccini, Barbara; Di Giuseppe, Dario; Bianchini, Gianluca; Coltorti, Massimo

2016-04-01

In this study, a C and N isotopic investigation in the soil-plant system of the ZeoLIFE project experimental field have been carried out. Since many years, natural and NH4-enriched zeolites have been used as soil amendant in agricultural context in order to reduce N losses, increase NUE (Nitrogen Use Efficiency) and crop yield. Nevertheless up to now there are no studies that, using the stable isotopes approach, highlighted the interaction between zeolites and plants in agricultural systems. The main aims of this study is to verify if natural zeolites amendment can enhance chemical fertilization efficiency and if N transfer from NH4-enriched zeolites to plants really occurs. Plants grown following traditional cultivation methods (with no zeolite addition) and plants grown on soils amended with natural and NH4-enriched zeolites (the latter obtained after mixing with pig-slurry with a very high 15N) were compared for two cultivation cycles (maize and wheat). As widely known, plants grown under conventional farming systems (use of chemical fertilizers as urea) and plants grown under organic farming can be discriminated by the isotopic signatures of plant tissues. For both years the main results of the study reveals that plants grown on plots amended with natural zeolites generally have their nitrogen isotopic signature more similar to that of the chemical fertilizers employed during the cultivation with respect to the plants cultivated in the non-amended plot. This suggests an enhanced N uptake by the plant from this specific N source with respect to the non-amended plot. On the other hand, plants grown on NH4-enriched zeolites registered a higher 15N, approaching the pig-slurry isotopic signature, confirming that this material can constitute an N pool for plants at least for two cultivation cycles. The distinct agricultural practices seem to be reflected in the plant physiology as recorded by the carbon discrimination factor (13C) which generally increases

Optimization for zeolite regeneration and nitrogen removal performance of a hypochlorite-chloride regenerant.

PubMed

Zhang, Wei; Zhou, Zhen; An, Ying; Du, Silu; Ruan, Danian; Zhao, Chengyue; Ren, Ning; Tian, Xiaoce

2017-07-01

Simultaneous zeolites regeneration and nitrogen removal were investigated by using a mixed solution of NaClO and NaCl (NaClO-NaCl solution), and effects of the regenerant on ammonium removal performance and textural properties of zeolites were analyzed by long-term adsorption and regeneration operations. Mixed NaClO-NaCl solution removed more NH 4 + exchanged on zeolites and converted more of them to nitrogen than using NaClO or NaCl solution alone. Response surface methodological analysis indicated that molar ratio of hypochlorite and nitrogen (ClO - /N), NaCl concentration and pH value all had significant effects on zeolites regeneration and NH 4 + conversion to nitrogen, and the optimum condition was obtained at ClO - /N of 1.75, NaCl concentration of 20 g/L and pH of 10.0. Zeolites regenerated by mixed NaClO-NaCl solution showed higher ammonium adsorption rate and lower capacity than unused zeolites. Zeolites and the regeneration solution were both effective even after 20 cycles of use. Composition and morphological analysis revealed that the main mineral species and surface morphology of zeolites before and after NaClO-NaCl regeneration were unchanged. Textural analysis indicated that NaClO-NaCl regeneration leads to an increased surface area of zeolites, especially the microporosity. The results indicated that NaClO-NaCl regeneration is an attractive method to achieve sustainable removal of nitrogen from wastewater through zeolite. Copyright © 2017 Elsevier Ltd. All rights reserved.

Removal of excess nutrients by Australian zeolite during anaerobic digestion of swine manure.

PubMed

Wijesinghe, D Thushari N; Dassanayake, Kithsiri B; Scales, Peter; Sommer, Sven G; Chen, Deli

2018-03-21

The objective of this study was to investigate the feasibility of using natural and NaCl-treated Australian zeolites to simultaneously remove excess nutrients from anaerobically digested swine manure. Ion adsorption and desorption properties of Australian zeolite during the anaerobic digestion of swine manure were investigated. Two experiments were conducted: the first was an adsorption experiment with multi-component solutions that corresponded with the ionic composition of swine manure digestates. The second experiment determined the effects of zeolite dose rates during anaerobic digestion of swine manure on the removal of N, P and K from solution. Adsorption isotherms confirmed selectivity for K + over NH 4 + by Australian natural and sodium zeolites. Therefore, NH 4 + removal was considerably reduced when there was simultaneous K + uptake. Natural zeolite desorbed more Ca 2+ during K + and NH 4 + adsorption than sodium zeolite. The ion exchange reaction was independent of the presence of P. P removal was very dependent on the pH of the medium. Natural Australian zeolite was shown to be a potential sorbent for the removal of NH 4 + , K + and P during the anaerobic digestion of swine manure. However, the application of high concentrations of zeolite at higher pH values (> 7.5) might not be appropriate for anaerobic digestion, because zeolite desorbed more Ca 2+ ions into the solution at the higher doses of zeolite and then availability of P for microbial growth might be reduced as a result of PO 4 3- precipitation with Ca 2+ at the higher pH.

The stability of copper oxo species in zeolite frameworks

DOE PAGES

Vilella, Laia; Studt, Felix

2016-03-07

Cu-exchanged zeolites are promising heterogeneous catalysts, as they provide a confined environment to carry out highly selective reactions. Furthermore, the knowledge of how the zeolite framework and the location of Al atoms therein affect the adsorption of copper species is still not well understood. In this work, DFT was used to investigate the adsorption of potential Cu oxo active species suggested in the literature [Cu(η 2-O 2), Cu(µ-O)Cu, and Cu 2O 2] into zeolites with different pore sizes and shapes (AFI, CHA, TON, MOR, and MFI). The calculations revealed that both monomeric and dimeric Cu oxo species bind strongly tomore » the O atoms of the lattice. For the monometallic species similar adsorption energies are obtained with the different zeolite frameworks, whereas an optimum Al–Al distance is required for the dimeric species.« less

Properties of Zeolite A Obtained from Powdered Laundry Detergent: An Undergraduate Experiment.

ERIC Educational Resources Information Center

Smoot, Alison L.; Lindquist, David A.

1997-01-01

Presents experiments that introduce students to the myriad properties of zeolites using the sodium form of zeolite A (Na-A) from laundry detergent. Experiments include extracting Na-A from detergent, water softening properties, desiccant properties, ion-exchange properties, and Zeolite HA as a dehydration catalyst. (JRH)

Effective solidification/stabilisation of mercury-contaminated wastes using zeolites and chemically bonded phosphate ceramics.

PubMed

Zhang, Shaoqing; Zhang, Xinyan; Xiong, Ya; Wang, Guoping; Zheng, Na

2015-02-01

In this study, two kinds of zeolites materials (natural zeolite and thiol-functionalised zeolite) were added to the chemically bonded phosphate ceramic processes to treat mercury-contaminated wastes. Strong promotion effects of zeolites (natural zeolite and thiol-functionalised zeolite) on the stability of mercury in the wastes were obtained and these technologies showed promising advantages toward the traditional Portland cement process, i.e. using Portland cement as a solidification agent and natural or thiol-functionalised zeolite as a stabilisation agent. Not only is a high stabilisation efficiency (lowered the Toxicity Characteristic Leaching Procedure Hg by above 10%) obtained, but also a lower dosage of solidification (for thiol-functionalised zeolite as stabilisation agent, 0.5 g g(-1) and 0.7 g g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) and stabilisation agents (for natural zeolite as stabilisation agent, 0.35 g g(-1) and 0.4 g g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) were used compared with the Portland cement process. Treated by thiol-functionalised zeolite and chemically bonded phosphate ceramic under optimum parameters, the waste containing 1500 mg Hg kg(-1) passed the Toxicity Characteristic Leaching Procedure test. Moreover, stabilisation/solidification technology using natural zeolite and chemically bonded phosphate ceramic also passed the Toxicity Characteristic Leaching Procedure test (the mercury waste containing 625 mg Hg kg(-1)). Moreover, the presence of chloride and phosphate did not have a negative effect on the chemically bonded phosphate ceramic/thiol-functionalised zeolite treatment process; thus, showing potential for future application in treatment of 'difficult-to-manage' mercury-contaminated wastes or landfill disposal with high phosphate and chloride content. © The Author(s) 2015.

Potential and challenges of zeolite chemistry in the catalytic conversion of biomass.

PubMed

Ennaert, Thijs; Van Aelst, Joost; Dijkmans, Jan; De Clercq, Rik; Schutyser, Wouter; Dusselier, Michiel; Verboekend, Danny; Sels, Bert F

2016-02-07

Increasing demand for sustainable chemicals and fuels has pushed academia and industry to search for alternative feedstocks replacing crude oil in traditional refineries. As a result, an immense academic attention has focused on the valorisation of biomass (components) and derived intermediates to generate valuable platform chemicals and fuels. Zeolite catalysis plays a distinct role in many of these biomass conversion routes. This contribution emphasizes the progress and potential in zeolite catalysed biomass conversions and relates these to concepts established in existing petrochemical processes. The application of zeolites, equipped with a variety of active sites, in Brønsted acid, Lewis acid, or multifunctional catalysed reactions is discussed and generalised to provide a comprehensive overview. In addition, the feedstock shift from crude oil to biomass involves new challenges in developing fields, like mesoporosity and pore interconnectivity of zeolites and stability of zeolites in liquid phase. Finally, the future challenges and perspectives of zeolites in the processing of biomass conversion are discussed.

Composting domestic sewage sludge with natural zeolites in a rotary drum reactor.

PubMed

Villaseñor, J; Rodríguez, L; Fernández, F J

2011-01-01

This work aimed the influence of zeolites addition on a sludge-straw composting process using a pilot-scale rotary drum reactor. The type and concentration of three commercial natural zeolites were considered: a mordenite and two clinoptilolites (Klinolith and Zeocat). Mordenite caused the greatest carbon removal (58%), while the clinoptilolites halved losses of ammonium. All zeolites removed 100% of Ni, Cr, Pb, and significant amounts (more than 60%) of Cu, Zn and Hg. Zeocat displayed the greatest retention of ammonium and metals, and retention efficiencies increased as Zeocat concentration increased. The addition of 10% Zeocat produced compost compliant with Spanish regulations. Zeolites were separated from the final compost, and leaching studies suggested that zeolites leachates contained very low metals concentrations (<1 mg/kg). Thus, the final compost could be applied directly to soil, or metal-polluted zeolites could be separated from the compost prior to application. The different options have been discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Selective adsorption of thiophene and 1-benzothiophene on metal-ion-exchanged zeolites in organic medium.

PubMed

Xue, Mei; Chitrakar, Ramesh; Sakane, Kohji; Hirotsu, Takahiro; Ooi, Kenta; Yoshimura, Yuji; Feng, Qi; Sumida, Naoto

2005-05-15

Adsorption of the organic sulfur compounds thiophene (TP) and 1-benzothiophene (1-BTP) in an organic model solution of hydrodesulfurizated gasoline (heptane with 1 wt% toluene and 0.156 mM (5 ppmw as sulfur) TP or 1-BTP) was studied by a batch method at 80 degrees C using metal-ion-exchanged Y-zeolites. Although NaY-zeolite or its acid-treated material rarely adsorbed the organic sulfur compounds, NaY-zeolites exchanged with Ag+, Cu2+, and Ce3+ ions and NH(4)Y-zeolites exchanged with Ce3+ ions showed markedly high adsorptive capacities for TP and 1-BTP. The sulfur uptake increased in the order CuY-zeolite(Na)(Na) for both the organic sulfur compounds. The adsorption isotherms for TP and 1-BTP followed the Langmuir's relationship and the saturation capacities by CeY-zeolite(Na) were calculated as 0.022 and 0.033 mmol/g, respectively. The mole ratios of TP/Ce and 1-BTP/Ce were 0.031 and 0.047, respectively. CeY-zeolite(NH4) which was prepared from NH4Y-zeolite showed less uptake of TP and 1-BTP than CeY-zeolite(Na), probably due to its lower cerium content.

Nanocomposites of zeolite-titanium(IV) oxides: Preparation, characterization, adsorption, photocatalytic and bactericidal properties

NASA Astrophysics Data System (ADS)

Domoroshchina, Elena; Kravchenko, Galina; Kuz'micheva, Galina

2017-06-01

NT/zeolite nanocomposites (NT - nanosized titanium(IV) oxides: η-phase and Hombifine N with anatase; zeolite: Beta(25), ZSM-5 with different modules Si/Al, MOR, or Y) have been obtained by two methods: modified cold-impregnation method (method 1) and in situ method of introduction of zeolites into the reaction mixture during the synthesis of NT by hydrolysis of TiOSO4×xH2SO4×yH2O or TiOSO4×2H2O aqueous solutions (method 2), performed for the first time. According to the X-ray data, the following differences in the NT:zeolite systems under investigation have been revealed: the mixture of zeolites and NT in nanocrystalline (Hombifine N/zeolite) or amorphous states (η-phase/zeolite, except for η-phase/MOR, where NT peaks are absent) (method 1), and the mixture of Y-zeolite and amorphous NT or only Y-zeolite without NT (method 2), which indicates the different levels of interaction between NT and zeolites in the systems studied. The best characteristics of properties (photocatalytic, adsorption, and antibacterial) have been revealed in the nanocomposites synthesized by the method 2. The correlation between the photoreaction rate constant (the k value) under UV irradiation in the presence of nanocomposites (kmax for NT/ZSM-5(12)) and the type of precursor, its pH, synthesis duration, NT:zeolite ratio, organic dye composition (methyl orange or Rhodamine G) has been established. The highest degree of extraction of P(V) ions from model aqueous systems has been observed in the presence of nanocomposites with the largest total surface area of all particles (Rmax = 99.48% for NT/MOR). The correlation between the sorption degree of P(V) ions and the modulus of zeolite is possible. Antibacterial activity in the dark towards Escherichia coli has been found for Y and Beta(25) zeolites and nanocomposites on their basis (methods 1 and 2) with the maximum diameter of bacterial growth inhibition (18 mm) obtained for NT/Beta(25) (method 2) synthesized only from TiOSO4×xH2SO4�

Identifying the Optimal Water-Occluding Earplugs: A Scientific Simulation Study.

PubMed

Kovoor, Joshua; Al Hussaini, Ali; Backhouse, Steven

2016-12-01

Numerous types of water-occluding earplugs are available as a means of preventing infection in patients with external and middle ear disease. However, little is known about the comparative efficacies of these earplugs with prolonged water exposure. In this study, we assessed the water impermeability of various earplug materials to prolonged water exposure. Nine earplugs were tested: cotton wool mixed with petroleum jelly, cotton wool externally coated with petroleum jelly, Blu-Tack, foam earplugs, silicone putty, silicone earplugs, flanged earplugs, and hard and soft silicone custom-moulds. Precision-engineered cups were filled with 30 mL water and sealed with lids that contained a 10 mm diameter hole to simulate the ear canal. The aperture was occluded with different earplugs, and the cup was inverted. Computer software was used to record the water loss to the nearest 10 milligrams 720 times over a three-hour period. The test was repeated five times for each material. The water permeability onset, rate, and total amount of water loss varied markedly between the materials; cotton wool mixed with petroleum jelly demonstrated the fastest onset of leak and the highest rate of water loss (p < 0.00001), as well as the largest amount of cumulative water loss (p = 0.00213). The soft silicone custom-mould plugs, hard silicone custom-mould plugs, foam plugs, and silicone putty demonstrated no leaks. This study demonstrates a wide range of water permeabilities of commonly used ear-occluding materials during prolonged water exposure. We found that the generally suggested regimen of cotton wool mixed with petroleum jelly may be inefficacious for substantial periods of water exposure.

Influence of Crystal Expansion/Contraction on Zeolite Membrane Permeation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sorenson, Stephanie G; Payzant, E Andrew; Noble, Richard D

X-ray diffraction was used to measure the unit cell parameters of B-ZSM-5, SAPO-34, and NaA zeolite powders as a function of adsorbate loading at 303 K, and in one case, at elevated temperatures. Most adsorbates expanded the zeolite crystals below saturation loading at 303 K: n-hexane and SF6 in B-ZSM-5, methanol and CO2 in SAPO-34, and methanol in NaA zeolite. As the loadings increased, the crystals expanded more. Changes in the unit cell volumes of B-ZSM-5 and SAPO-34 zeolite powders correlated with changes in permeation through zeolite membranes defects. When the zeolite crystals expanded or contracted upon adsorption, the defectmore » sizes decreased or increased. In B-ZSM-5 membranes, the fluxes through defects decreased dramatically when n-hexane or SF6 adsorbed. In contrast, i-butane adsorption at 303 K contracted B-ZSM-5 crystals at low loadings and expanded them at higher loadings. Correspondingly, the flux through B-ZSM-5 membrane defects increased at low i-butane loadings and decreased at high loading because the defects increased in size at low loading and decreased at high loadings. At 398 K and 473 K, n-hexane expanded the B-ZSM-5 unit cell more as the temperature increased from 303 to 473 K. The silicalite-1 and B-ZSM-5 unit cell volumes expanded similarly upon n-hexane adsorption at 303 K; boron substitution had little effect on volume expansion.« less

The remediation of the lead-polluted garden soil by natural zeolite.

PubMed

Li, Hua; Shi, Wei-yu; Shao, Hong-bo; Shao, Ming-an

2009-09-30

The current study investigated the remediation effect of lead-polluted garden soil by natural zeolite in terms of soil properties, Pb fraction of sequential extraction in soil and distribution of Pb in different parts of rape. Natural zeolite was added to artificially polluted garden soil to immobilize and limit the uptake of lead by rape through changing soil physical and chemical properties in the pot experiment under greenhouse conditions. Results indicated that the addition of natural zeolite could increase soil pH, CEC, content of soil organic matter and promote formation of soil aggregate. The application of zeolite decreased the available fraction of Pb in the garden soil by adjusting soil pH rather than CEC, and restrained the Pb uptake by rape. Data obtained suggested that the application of a dose of zeolite was adequate (>or=10 g kg(-1)) to reduce soluble lead significantly, even if lead pollution is severe in garden soil (>or=1000 mg kg(-1)). An appropriate dose of zeolite (20 g kg(-1)) could reduce the Pb concentration in the edible part (shoots) of rape up to 30% of Pb in the seriously polluted soil (2000 mg kg(-1)).

3D Study of the Morphology and Dynamics of Zeolite Nucleation.

PubMed

Melinte, Georgian; Georgieva, Veselina; Springuel-Huet, Marie-Anne; Nossov, Andreï; Ersen, Ovidiu; Guenneau, Flavien; Gedeon, Antoine; Palčić, Ana; Bozhilov, Krassimir N; Pham-Huu, Cuong; Qiu, Shilun; Mintova, Svetlana; Valtchev, Valentin

2015-12-07

The principle aspects and constraints of the dynamics and kinetics of zeolite nucleation in hydrogel systems are analyzed on the basis of a model Na-rich aluminosilicate system. A detailed time-series EMT-type zeolite crystallization study in the model hydrogel system was performed to elucidate the topological and temporal aspects of zeolite nucleation. A comprehensive set of analytical tools and methods was employed to analyze the gel evolution and complement the primary methods of transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR) spectroscopy. TEM tomography reveals that the initial gel particles exhibit a core-shell structure. Zeolite nucleation is topologically limited to this shell structure and the kinetics of nucleation is controlled by the shell integrity. The induction period extends to the moment when the shell is consumed and the bulk solution can react with the core of the gel particles. These new findings, in particular the importance of the gel particle shell in zeolite nucleation, can be used to control the growth process and properties of zeolites formed in hydrogels. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zeolite crystal growth in space - What has been learned

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

Effect of zeolite catalyst on sugar dehydration for 5-Hydroxymethylfurfural synthesis

NASA Astrophysics Data System (ADS)

Mostapha, Marhaini; Jahar, Noorhasmiera Abu; Chin, Siew Xian; Jaafar, Sharifah Nabihah Syed; Zakaria, Sarani; Aizat, Wan M.; Azizan, Kamalrul Azlan

2016-11-01

The effectiveness in the dehydration of sugars into 5-Hydroxymethylfurfural is related to the catalyst existence. A comprehensive synthesis of 5-Hydroxymethylfurfural from fructose, glucose and sucrose (3.73 mmol) with and without addition zeolite catalyst was performed in this study. The reactions were carried out in water-methanol solvent system for 3 hours reaction time at 180°C temperature. The catalytic results from HPLC showed that the reaction with zeolite increases the yield of 5-Hydroxymethylfurfural with 51.72 %, 34.01% and 50.10% for fructose, glucose and sucrose respectively. The study suggests that zeolites promote the isomerization of glucose into fructose to occur and simultaneously catalyze the dehydration of fructose into 5-Hydroxymethylfurfural. Only slight changes on FT-IR spectra of use zeolite after the reaction was observed. Thus suggest that zeolite was a potential catalyst for catalytic reaction for the conversion of sugar into 5-Hydroxymethylfurfural.

Microwave-assisted regeneration of synthetic zeolite used in tritium removal systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, M.; Takayama, S.; Sano, S.

The regeneration process using synthetic honeycomb type 5A zeolite under microwave irradiation was experimentally investigated using a single-mode cavity at 2.46 GHz. In order to investigate the effect of electromagnetic fields, inductive heating by a magnetic field was applied to synthetic zeolite containing water. Because the microwave energy absorbed in the sample was less than 15 W, the zeolite sample was only heated to a temperature of 71 C. degrees. Water desorption was observed based on the increased temperature of the zeolite sample and the thermogravimetric curve that indicated a single step phenomenon. As a result, the regeneration process ofmore » zeolite was not complete over a period of 6000 s. A comparison of dielectric heating by an electric field with inductive heating by a magnetic field showed that the regeneration process by microwave irradiation was particularly beneficial in dielectric heating. (authors)« less

Lack of benefit from percutaneous intervention of persistently occluded infarct arteries after the acute phase of myocardial infarction is time independent: insights from Occluded Artery Trial

PubMed Central

Menon, Venu; Pearte, Camille A.; Buller, Christopher E.; Steg, Ph.Gabriel; Forman, Sandra A.; White, Harvey D.; Marino, Paolo N.; Katritsis, Demosthenes G.; Caramori, Paulo; Lasevitch, Ricardo; Loboz-Grudzien, Krystyna; Zurakowski, Aleksander; Lamas, Gervasio A.; Hochman, Judith S.

2009-01-01

Aims The Occluded Artery Trial (OAT) (n = 2201) showed no benefit for routine percutaneous intervention (PCI) (n = 1101) over medical therapy (MED) (n = 1100) on the combined endpoint of death, myocardial infarction (MI), and class IV heart failure (congestive heart failure) in stable post-MI patients with late occluded infarct-related arteries (IRAs). We evaluated the potential for selective benefit with PCI over MED for patients enrolled early in OAT. Methods and results We explored outcomes with PCI over MED in patients randomized to the ≤3 calendar days and ≤7 calendar days post-MI time windows. Earlier, times to randomization in OAT were associated with higher rates of the combined endpoint (adjusted HR 1.04/day: 99% CI 1.01–1.06; P < 0.001). The 48-month event rates for ≤3 days, ≤7 days post-MI enrolled patients were similar for PCI vs. MED for the combined and individual endpoints. There was no interaction between time to randomization defined as a continuous (P = 0.55) or categorical variable with a cut-point of 3 days (P = 0.98) or 7 days (P = 0.64) post-MI and treatment effect. Conclusion Consistent with overall OAT findings, patients enrolled in the ≤3 day and ≤7 day post-MI time windows derived no benefit with PCI over MED with no interaction between time to randomization and treatment effect. Our findings do not support routine PCI of the occluded IRA in trial-eligible patients even in the earliest 24–72 h time window. PMID:19028780

Purification of metal finishing waste waters with zeolites and activated carbons.

PubMed

Leinonen, H; Lehto, J

2001-02-01

Sixteen zeolites and 5 activated carbons were tested for the removal of nickel, zinc, cadmium, copper, chromium, and cobalt from waste simulants mimicking effluents produced in metal plating plants. The best performances were obtained from 4 zeolites: A, X, L, and ferrierite types and from 2 carbon types made from lignite and peat. The distribution coefficients for these sorbents were in the range of 10,000-440,000 ml/g. Column experiments showed that the most effective zeolites for Zn, Ni, Cu, and Cd were A and X type zeolites. The activated carbons, Hydrodarco 3000 and Norit Row Supra, exhibited good sorption properties for metals in aqueous solutions containing complexing agents.

Removal of Ca2+ and Zn2+ from aqueous solutions by zeolites NaP and KP.

PubMed

Yusof, Alias Mohd; Malek, Nik Ahmad Nizam Nik; Kamaruzaman, Nurul Asyikin; Adil, Muhammad

2010-01-01

Zeolites P in sodium (NaP) and potassium (KP) forms were used as adsorbents for the removal of calcium (Ca2+) and zinc (Zn2+) cations from aqueous solutions. Zeolite KP was prepared by ion exchange of K+ with Na+ which neutralizes the negative charge of the zeolite P framework structure. The ion exchange capacity of K+ on zeolite NaP was determined through the Freundlich isotherm equilibrium study. Characterization of zeolite KP was determined using infrared spectroscopy and X-ray diffraction (XRD) techniques. From the characterization, the structure of zeolite KP was found to remain stable after the ion exchange process. Zeolites KP and NaP were used for the removal of Ca and Zn from solution. The amount of Ca2+ and Zn2+ in aqueous solution before and after the adsorption by zeolites was analysed using the flame atomic absorption spectroscopy method. The removal of Ca2+ and Zn2+ followed the Freundlich isotherm rather than the Langmuir isotherm model. This result also revealed that zeolite KP adsorbs Ca2+ and Zn2+ more than zeolite NaP and proved that modification of zeolite NaP with potassium leads to an increase in the adsorption efficiency of the zeolite. Therefore, the zeolites NaP and KP can be used for water softening (Ca removal) and reducing water pollution/toxicity (Zn removal).

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.

Dentinal tubules occluded by bioactive glass-containing toothpaste exhibit high resistance toward acidic soft drink challenge.

PubMed

Bakri, M M; Hossain, M Z; Razak, F A; Saqina, Z H; Misroni, A A; Ab-Murat, N; Kitagawa, J; Saub, R B

2017-06-01

Dentine hypersensitivity is a common problem attributed by patent dentinal tubules. Ingredients incorporated in toothpastes aim to occlude patent dentinal tubules to minimize the dentine hypersensitivity. However, frequent consumption of acidic soft drinks may reverse the dentinal tubules' occlusion. In this in vitro study, the efficacy of dentinal tubules occluded by commercially available toothpastes to withstand different durations of an acidic soft drink challenge was investigated. One hundred and twenty dentine discs were divided into three groups. The discs from each group were brushed with toothpaste containing bioactive glass, arginine and control toothpaste. Each group was then divided into four subgroups and exposed to acidic soft drink over four different time durations. The scoring and the percentage of occluded dentinal tubules by Novamin-containing toothpaste was significantly better compared with arginine or the control toothpaste. Acidic soft drink challenge reduced the extent of dentinal tubules occlusion along with time. Dentinal tubules occluded by Novamin-containing toothpaste withstand the acidic challenge comparatively for a longer period. The findings demonstrated that occlusion of dentinal tubules is more efficient by the bioactive glass-containing toothpaste and thus may contribute to its better resistance to acidic soft drink challenge. © 2016 Australian Dental Association.

New ion-exchanged zeolite derivatives: antifungal and antimycotoxin properties against Aspergillus flavus and aflatoxin B1

NASA Astrophysics Data System (ADS)

Savi, Geovana D.; Cardoso, Willian A.; Furtado, Bianca G.; Bortolotto, Tiago; Da Agostin, Luciana O. V.; Nones, Janaína; Torres Zanoni, Elton; Montedo, Oscar R. K.; Angioletto, Elidio

2017-08-01

Zeolites are microporous crystalline hydrated aluminosilicates with absorbent and catalytic properties. This material can be used in many applications in stored-pest management such as: pesticide and fertilizer carriers, animal feed additives, mycotoxin binders and food packaging materials. Herein, four 4A zeolite forms were prepared by ion-exchange and their antifungal effect against Aspergillus flavus was highlighted. Additionally, the antimycotoxin activity and the aflatoxin B1 (AFB1) adsorption capacity of these zeolites as well as their toxic effects on Artemia sp. were investigated. The ion-exchanged zeolites with Li+ and Cu2+ showed the best antifungal activity against A. flavus, including effects on conidia germination and hyphae morphological alterations. Regarding to antimycotoxin activity, all zeolite samples efficiently inhibited the AFB1 production by A. flavus. However, the ion-exchanged zeolites exhibited better results than the 4A zeolite. On the other hand, the AFB1 adsorption capacity was only observed by the 4A zeolite and zeolite-Li+. Lastly, our data showed that all zeolites samples used at effective concentrations for antifungal and antimycotoxin assays (2 mg ml-1) showed no toxic effects towards Artemia sp. Results suggest that some these ion-exchanged zeolites have great potential as an effective fungicide and antimycotoxin agent for agricultural and food safety applications.

Pore Topology Effects in Positron Annihilation Spectroscopy of Zeolites.

PubMed

Zubiaga, Asier; Warringham, Robbie; Mitchell, Sharon; Gerchow, Lars; Cooke, David; Crivelli, Paolo; Pérez-Ramírez, Javier

2017-03-03

Positron annihilation spectroscopy (PAS) is a powerful method to study the size and connectivity of pores in zeolites. The lifetime of positronium within the host material is commonly described by the Tao-Eldrup model. However, one of its largest limitations arises from the simple geometries considered for the shape of the pores, which cannot describe accurately the complex topologies in zeolites. Here, an atomic model that combines the Tao potential with the crystallographic structure is introduced to calculate the distribution and lifetime of Ps intrinsic to a given framework. A parametrization of the model is undertaken for a set of widely applied zeolite framework types (*BEA, FAU, FER, MFI, MOR, UTL), before extending the model to all known structures. The results are compared to structural and topological descriptors, and to the Tao-Eldrup model adapted for zeolites, demonstrating the intricate dependence of the lifetime on the pore architecture. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selective methane chlorination to methyl chloride by zeolite Y-based catalysts

NASA Astrophysics Data System (ADS)

Joo, Hyeonho; Kim, Daeho; Lim, Kwang Soo; Choi, Yong Nam; Na, Kyungsu

2018-03-01

The CH4 chlorination over Y zeolites was investigated to produce CH3Cl in a high yield. Three different catalytic systems based on Y zeolite were tested for enhancement of CH4 conversion and CH3Cl selectivity: (i) HY zeolites in H+-form having various Si/Al ratios, (ii) Pt/HY zeolites supporting Pt metal nanoparticles, (iii) Pt/NaY zeolites in Na+-form supporting Pt metal nanoparticles. The reaction was carried out using the gas mixture of CH4 and Cl2 with the respective flow rates of 15 and 10 mL min-1 at 300-350 °C using a fixed-bed reactor under a continuous gas flow condition (gas hourly space velocity = 3000 mL g-1 h-1). Above the reaction temperature of 300 °C, the CH4 chlorination is spontaneous even in the absence of catalyst, achieving 23.6% of CH4 conversion with 73.4% of CH3Cl selectivity. Under sufficient supplement of thermal energy, Cl2 molecules can be dissociated to two chlorine radicals, which triggered the C-H bond activation of CH4 molecule and thereby various chlorinated methane products (i.e., CH3Cl, CH2Cl2, CHCl3, CCl4) could be produced. When the catalysts were used under the same reaction condition, enhancement in the CH4 conversion was observed. The Pt-free HY zeolite series with varied Si/Al ratios gave around 27% of CH4 conversion, but there was a slight decrease in CH3Cl selectivity with about 64%. Despite the difference in acidity of HY zeolites having different Si/Al ratios, no prominent effect of the Si/Al ratios on the catalytic performance was observed. This suggests that the catalytic contribution of HY zeolites under the present reaction condition is not strong enough to overcome the spontaneous CH4 chlorination. When the Pt/HY zeolite catalysts were used, the CH4 conversion reached further up to 30% but the CH3Cl selectivity decreased to 60%. Such an enhancement of CH4 conversion could be attributed to the strong catalytic activity of HY and Pt/HY zeolite catalysts. However, both catalysts induced the radical cleavage of Cl2

Electronic eye occluder with time-counting and reflection control

NASA Astrophysics Data System (ADS)

Karitans, V.; Ozolinsh, M.; Kuprisha, G.

2008-09-01

In pediatric ophthalmology 2 - 3 % of all the children are impacted by a visual pathology - amblyopia. It develops if a clear image isn't presented to the retina during an early stage of the development of the visual system. A common way of treating this pathology is to cover the better-seeing eye to force the "lazy" eye to learn seeing. However, children are often reluctant to wear such an occluder because they are ashamed or simply because they find it inconvenient. This fact requires to find a way how to track the regime of occlusion because results of occlusion is a hint that the actual regime of occlusion isn't that what the optometrist has recommended. We design an electronic eye occluder that allows to track the regime of eye occlusion. We employ real-time clock DS1302 providing time information from seconds to years. Data is stored in the internal memory of the CPU (EEPROM). The MCU (PIC16F676) switches on only if a mechanical switch is closed and temperature has reached a satisfactory level. The occlusion is registered between time moments when the infrared signal appeared and disappeared.

Evaluation of synthetic zeolites as oral delivery vehicle for anti-inflammatory drugs

PubMed Central

Khodaverdi, Elham; Honarmandi, Reza; Alibolandi, Mona; Baygi, Roxana Rafatpanah; Hadizadeh, Farzin; Zohuri, Gholamhossein

2014-01-01

Objective(s): In this research, zeolite X and zeolite Y were used as vehicle to prepare intestine targeted oral delivery systems of indomethacin and ibuprofen. Materials and Methods: A soaking procedure was implemented to encapsulate indomethacin or ibuprofen within synthetic zeolites. Gravimetric methods and IR spectra of prepared formulations were used to assess drug loading efficiencies into zeolite structures. Scanning Electron Microscopy (SEM) was also utilized to determine morphologies changes in synthetic zeolites after drug loading. At the next stage, dissolution studies were used to predict the in vivo performance of prepared formulations at HCl 0.1 N and PBS pH 6.5 as simulated gastric fluid (SGF) and simulated intestine fluid (SIF), respectively. Results: Drug loadings of prepared formulations was determined between 24-26 % w/w. Dissolution tests at SGF were shown that zeolites could retain acidic model drugs in their porous structures and can be able to limit their release into the stomach. On the other hand, all prepared formulations completely released model drugs during 3 hr in simulated intestine fluid. Conclusion: Obtained results indicated zeolites could potentially be able to release indomethacin and ibuprofen in a sustained and controlled manner and reduced adverse effects commonly accompanying oral administrations of NSAIDs. PMID:24967062

Occluded Brescia-Cimino Hemodialysis Fistulas: Endovascular Treatment with Both Brachial Arterial and Venous Access Using the Pull-Through Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyayama, Shiro; Matsui, Osamu; Taki, Keiichi

2005-12-15

We retrospectively evaluated the usefulness of both arterial and venous access with the pull-through technique in endovascular treatment of totally occluded Brescia-Cimino fistulas. We treated 26 patients (17 men, 9 women; age range 43-82 years, mean age 66 years) with occluded Brescia-Cimino fistulas. First, the occluded segment was traversed from the antegrade brachial arterial access using a microcatheter-guidewire system. Second, the vein was retrogradely punctured after confirmation of all diseased segments, and a 0.014- or 0.016-inch guidewire was pulled through the venous access when the occluded segment was long. All interventions including thrombolysis, thromboaspiration, angioplasty, and stent placement were performedmore » via the venous access. The occlusion was successfully crossed via the brachial arterial access in 23 patients (88%). In 2 patients it was done from the venous approach. In the remaining patient it was not possible to traverse the occluded segment. The pull-through technique was successful in all 19 attempts. Clinical success was achieved in 96%, the primary patency rates at 6, 12, and 18 months were 83%, 78%, and 69%, the primary assisted patency rates were 92%, 92%, and 72%, and the secondary patency rates were 92%, 92%, and 92%, respectively. Minor complications in 5 patients included venous perforation in 2 (8%), venous rupture in 1 (4%), and regional hematoma in 2 (8%). Our study suggests that endovascular treatments with both arterial and venous access using the pull-through technique are highly effective in restoring function in totally occluded Brescia-Cimino fistulas.« less

Molecular simulation of water removal from simple gases with zeolite NaA.

PubMed

Csányi, Eva; Ható, Zoltán; Kristóf, Tamás

2012-06-01

Water vapor removal from some simple gases using zeolite NaA was studied by molecular simulation. The equilibrium adsorption properties of H(2)O, CO, H(2), CH(4) and their mixtures in dehydrated zeolite NaA were computed by grand canonical Monte Carlo simulations. The simulations employed Lennard-Jones + Coulomb type effective pair potential models, which are suitable for the reproduction of thermodynamic properties of pure substances. Based on the comparison of the simulation results with experimental data for single-component adsorption at different temperatures and pressures, a modified interaction potential model for the zeolite is proposed. In the adsorption simulations with mixtures presented here, zeolite exhibits extremely high selectivity of water to the investigated weakly polar/non-polar gases demonstrating the excellent dehydration ability of zeolite NaA in engineering applications.

Synthesis of zeolite NaA membrane from fused fly ash extract.

PubMed

Ameh, Alechine E; Musyoka, Nicholas M; Fatoba, Ojo O; Syrtsova, Daria A; Teplyakov, Vladimir V; Petrik, Leslie F

2016-01-01

Zeolite-NaA membranes were synthesized from an extract of fused South African fly ash on a porous titanium support by a secondary growth method. The influence of the synthesis molar regime on the formation of zeolite NaA membrane layer was investigated. Two synthesis mixtures were generated by adding either aluminium hydroxide or sodium aluminate to the fused fly ash extract. The feedstock material and the synthesized membranes were characterized by X-diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). It was found by XRD and SEM that the cubic crystals of a typical zeolite NaA with a dense intergrown layer was formed on the porous Ti support. The study shows that the source of Al used had an effect on the membrane integrity as sodium aluminate provided the appropriate amount of Na(+) to form a coherent membrane of zeolite NaA, whereas aluminium hydroxide did not. Morphological, the single hydrothermal stage seeded support formed an interlocked array of zeolite NaA particles with neighbouring crystals. Also, a robust, continuous and well-intergrown zeolite NaA membrane was formed with neighbouring crystals of zeolite fused to each other after the multiple stage synthesis. The synthesized membrane was permeable to He (6.0 × 10(6) L m(-2)h(-1) atm(-1)) and CO2 (5.6 × 10(6) L m(-2)h(-1) atm(-1)), which indicate that the layer of the membrane was firmly attached to the porous Ti support. Membrane selectivity was maintained showing membrane integrity with permselectivity of 1.1, showing that a waste feedstock, fly ash, could be utilized for preparing robust zeolite NaA membranes on Ti support.

A unified computational model of the development of object unity, object permanence, and occluded object trajectory perception.

PubMed

Franz, A; Triesch, J

2010-12-01

The perception of the unity of objects, their permanence when out of sight, and the ability to perceive continuous object trajectories even during occlusion belong to the first and most important capacities that infants have to acquire. Despite much research a unified model of the development of these abilities is still missing. Here we make an attempt to provide such a unified model. We present a recurrent artificial neural network that learns to predict the motion of stimuli occluding each other and that develops representations of occluded object parts. It represents completely occluded, moving objects for several time steps and successfully predicts their reappearance after occlusion. This framework allows us to account for a broad range of experimental data. Specifically, the model explains how the perception of object unity develops, the role of the width of the occluders, and it also accounts for differences between data for moving and stationary stimuli. We demonstrate that these abilities can be acquired by learning to predict the sensory input. The model makes specific predictions and provides a unifying framework that has the potential to be extended to other visual event categories. Copyright © 2010 Elsevier Inc. All rights reserved.

Framework Stabilization of Si-Rich LTA Zeolite Prepared in Organic-Free Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conato, Marlon T.; Oleksiak, Matthew D.; McGrail, B. Peter

2014-10-16

Zeolite HOU-2 (LTA type) is prepared with the highest silica content (Si/Al = 2.1) reported for Na-LTA zeolites without the use of an organic structure-directing agent. The rational design of Si-rich zeolites has the potential to improve their thermal stability for applications in catalysis, gas storage, and selective separations.

Removal of calcium and magnesium ions from shale gas flowback water by chemically activated zeolite.

PubMed

Chang, Haiqing; Liu, Teng; He, Qiping; Li, Duo; Crittenden, John; Liu, Baicang

2017-07-01

Shale gas has become a new sweet spot of global oil and gas exploration, and the large amount of flowback water produced during shale gas extraction is attracting increased attention. Internal recycling of flowback water for future hydraulic fracturing is currently the most effective, and it is necessary to decrease the content of divalent cations for eliminating scaling and maintaining effectiveness of friction reducer. Zeolite has been widely used as a sorbent to remove cations from wastewater. This work was carried out to investigate the effects of zeolite type, zeolite form, activation chemical, activation condition, and sorption condition on removal of Ca 2+ and Mg 2+ from shale gas flowback water. Results showed that low removal of Ca 2+ and Mg 2+ was found for raw zeolite 4A and zeolite 13X, and the efficiency of the mixture of both zeolites was slightly higher. Compared with the raw zeolites, the zeolites after activation using NaOH and NaCl greatly improved the sorption performance, and there was no significant difference between dynamic activation and static activation. Dynamic sorption outperformed static sorption, the difference exceeding 40% and 7-70% for removal of Ca 2+ and Mg 2+ , respectively. Moreover, powdered zeolites outperformed granulated zeolites in divalent cation removal.

The growth of zeolites A, X and mordenite in space

NASA Technical Reports Server (NTRS)

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

1994-01-01

Zeolites are a class of crystalline aluminosilicate materials that form the backbone of the chemical process industry worldwide. They are used primarily as adsorbents and catalysts and support to a significant extent the positive balance of trade realized by the chemical industry in the United States (around $19 billion in 1991). The magnitude of their efforts can be appreciated when one realizes that since their introduction as 'cracking catalysts' in the early 1960's, they have saved the equivalent of 60 percent of the total oil production from Alaska's North Slope. Thus the performance of zeolite catalysts can have a profound effect on the U.S. economy. It is estimated that a 1 percent increase in yield of the gasoline fraction per barrel of oil would represent a savings of 22 million barrels of crude oil per year, representing a reduction of $400 million in the United States' balance of payments. Thus any activity that results in improvement in zeolite catalyst performance is of significant scientific and industrial interest. In addition, due to their 'stability,' uniformity, and, within limits, their 'engineerable' structures, zeolites are being tested as potential adsorbents to purify gases and liquids at the parts-per-billion levels needed in today's electronic, biomedical, and biotechnology industries and for the environment. Other exotic applications, such as host materials for quantum-confined semiconductor atomic arrays, are also being investigated. Because of the importance of this class of material, extensive efforts have been made to characterize their structures and to understand their nucleation and growth mechanisms, so as to be able to custom-make zeolites for a desired application. To date, both the nucleation mechanics and chemistry (such as what are the 'key' nutrients) are, as yet, still unknown for many, if not all, systems. The problem is compounded because there is usually a 'gel' phase present that is assumed to control the degree of

Safety and efficacy of transcatheter closure of large patent ductus arteriosus in adults with a self-expandable occluder.

PubMed

Yu, Man-Li; Huang, Xin-Miao; Wang, Jia-Feng; Qin, Yong-Wen; Zhao, Xian-Xian; Zheng, Xing

2009-11-01

Most occurrences of large patent ductus arteriosus (PDAs) of > or =10 mm have been surgically closed, and transcatheter closure of these large PDAs was only reported in a few case reports. The present study reviewed our experience in transcatheter closure of such large PDAs with a Chinese self-expandable occluder, which is similar to but much cheaper than the Amplatzer occluder. From July 2000 to January 2008, 23 patients underwent transcatheter closure of large PDA > or =10 mm with this kind of occluder. The mean (SD) age of the patients was 38.0 (15.6) years (range 18-75 years). Radiographs of the chest, electrocardiograms, and echocardiograms were used for follow-up evaluation of the treatment within 1 day, 1 month, 6 months, and then every year after successful closure. The mean (SD) angiographic PDA diameter was 12.8 (2.6) mm (range 10-18 mm) and the mean occluder diameter was 18.0 (2.9) mm (range 16-22 mm). The occluders were delivered successfully and closed the PDA completely in 19 out of the 23 patients. Pulmonary arterial pressures decreased significantly after occlusion in patients with successful treatment: 67.3 (24.7) mmHg (range 29-122 mmHg) before occlusion and 42.3 (22.0) mmHg (range 19-98 mmHg) immediately after the procedure. Radiographs of the chest and echocardiograms showed that the diameters of the left atrium, left ventricle, and the main pulmonary artery decreased, and the ejection fraction (EF) increased at a mean (SD) follow-up of 36.3 (18.7) months (range 6-72 months). No severe complication occurred. The immediate and long-term outcomes suggested that transcatheter closure of PDAs with the native PDA occluder is a safe and effective treatment for adults with large PDA > or =10 mm.

Association between autistic traits and emotion adaptation to partially occluded faces.

PubMed

Luo, Chengwen; Burns, Edwin; Xu, Hong

2017-04-01

Prolonged exposure to a happy face makes subsequently presented faces appear sadder: the facial emotion aftereffect (FEA). People with autism spectrum disorders and their relatives have diminished holistic perception of faces. Levels of autism can be measured continuously in the general population by autistic traits using the autism-quotient (AQ). Prior work has not found any association between AQ and FEA in adults, possibly due to non-holistic processing strategies employed by those at the higher end of the spectrum. In the present study, we tested whether AQ was associated with FEA to partially occluded faces. We hypothesized that inferring emotion from such faces would require participants to process their viewable parts as a gestalt percept, thus we anticipated this ability would diminish as autistic traits increased. In Experiment 1, we partially occluded the adapting faces with aligned or misaligned opaque bars. Both conditions produced significant FEAs, with aftereffects and AQ negatively correlated. In Experiment 2, we adapted participants to obscured faces flickering in luminance, and manipulated the facilitation of holistic perception by varying the synchronization of this flickering. We found significant FEAs in all conditions, but abolished its association with AQ. In Experiment 3, we showed that the association between AQ and FEA in the occluded conditions in Experiment 1 was not due to the recognizability or perceived emotional intensity of our adaptors; although the overall FEAs were linked to emotional intensity. We propose that increasing autistic traits are associated with diminishing abilities in perceiving emotional faces as a gestalt percept. Copyright © 2017 Elsevier Ltd. All rights reserved.

Morpho-chemical characterization and surface properties of carcinogenic zeolite fibers.

PubMed

Mattioli, Michele; Giordani, Matteo; Dogan, Meral; Cangiotti, Michela; Avella, Giuseppe; Giorgi, Rodorico; Dogan, A Umran; Ottaviani, Maria Francesca

2016-04-05

Erionite belonging to the zeolite family is a human health-hazard, since it was demonstrated to be carcinogenic. Conversely, offretite family zeolites were suspected carcinogenic. Mineralogical, morphological, chemical, and surface characterizations were performed on two erionites (GF1, MD8) and one offretite (BV12) fibrous samples and, for comparison, one scolecite (SC1) sample. The specific surface area analysis indicated a larger availability of surface sites for the adsorption onto GF1, while SC1 shows the lowest one and the presence of large pores in the poorly fibrous zeolite aggregates. Selected spin probes revealed a high adsorption capacity of GF1 compared to the other zeolites, but the polar/charged interacting sites were well distributed, intercalated by less polar sites (Si-O-Si). MD8 surface is less homogeneous and the polar/charged sites are more interacting and closer to each other compared to GF1. The interacting ability of BV12 surface is much lower than that found for GF1 and MD8 and the probes are trapped in small pores into the fibrous aggregates. In comparison with the other zeolites, the non-carcinogenic SC1 shows a poor interacting ability and a lower surface polarity. These results helped to clarify the chemical properties and the surface interacting ability of these zeolite fibers which may be related to their carcinogenicity. Copyright © 2015 Elsevier B.V. All rights reserved.

Selective thermal oxidation of hydrocarbons in zeolites by oxygen

DOEpatents

Frei, Heinz; Blatter, Fritz; Sun, Hai

2000-01-01

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

Rapid-synthesis of zeolite T via sonochemical-assisted hydrothermal growth method.

PubMed

Jusoh, Norwahyu; Yeong, Yin Fong; Mohamad, Maisarah; Lau, Kok Keong; M Shariff, Azmi

2017-01-01

Sonochemical-assisted method has been identified as one of the potential pre-treatment methods which could reduce the formation duration of zeolite as well as other microporous and mesoporous materials. In the present work, zeolite T was synthesized via sonochemical-assisted pre-treatment prior to hydrothermal growth. The durations for sonochemical-assisted pre-treatment were varied from 30min to 90min. Meanwhile, the hydrothermal growth durations were ranged from 0.5 to 3days. The physicochemical properties of the resulting samples were characterized using XRD, FESEM, FTIR and BET. As verified by XRD, the samples synthesized via hydrothermal growth durations of 1, 2 and 3days and sonochemical-assisted pre-treatment durations of 60min and 90min demonstrated zeolite T structure. The samples which underwent sonochemical-assisted pre-treatment duration of 60min yielded higher crystallinity with negligible change of zeolite T morphology. Overall, the lengthy synthesis duration of zeolite T has been successfully reduced from 7days to 1day by applying sonochemical-assisted pre-treatment of 60min, while synthesis duration of 0.5days via sonochemical-assisted pre-treatment of 60min was not sufficient to produce zeolite T structure. Copyright © 2016 Elsevier B.V. All rights reserved.

Polymethylated [4.1.1] Octanes Leading to Zeolite SSZ-50

NASA Astrophysics Data System (ADS)

Lee, Greg S.; Zones, Stacey I.

2002-09-01

In this communication, we report on the discovery of novel zeolite compositions, SSZ-50. The zeolite has the RTH topology but can be made over a large silica-to-alumina range including no aluminum at all. The surprising capability to produce a broad compositional range comes from the use of a single organo-cation guest molecule in the zeolite synthesis. The molecule is a specific derivative from within a family of 2-aza [4.1.1] bicyclo octanes that were prepared employing a sequence of organic synthesis steps from a starting ketone. Other cage-based zeolites like SSZ-35,-36,-39 and MTN arose from the use of the other derivatives in this series. We also comment on the tendency of a variety of polymethylated organo-cations to produce RTH, the closely related ITE, or the intergrowth structure, SSZ-36.

A family of zeolites with controlled pore size prepared using a top-down method

NASA Astrophysics Data System (ADS)

Roth, Wieslaw J.; Nachtigall, Petr; Morris, Russell E.; Wheatley, Paul S.; Seymour, Valerie R.; Ashbrook, Sharon E.; Chlubná, Pavla; Grajciar, Lukáš; Položij, Miroslav; Zukal, Arnošt; Shvets, Oleksiy; Čejka, Jiří

2013-07-01

The properties of zeolites, and thus their suitability for different applications, are intimately connected with their structures. Synthesizing specific architectures is therefore important, but has remained challenging. Here we report a top-down strategy that involves the disassembly of a parent zeolite, UTL, and its reassembly into two zeolites with targeted topologies, IPC-2 and IPC-4. The three zeolites are closely related as they adopt the same layered structure, and they differ only in how the layers are connected. Choosing different linkers gives rise to different pore sizes, enabling the synthesis of materials with predetermined pore architectures. The structures of the resulting zeolites were characterized by interpreting the X-ray powder-diffraction patterns through models using computational methods; IPC-2 exhibits orthogonal 12- and ten-ring channels, and IPC-4 is a more complex zeolite that comprises orthogonal ten- and eight-ring channels. We describe how this method enables the preparation of functional materials and discuss its potential for targeting other new zeolites.

Synthesis and characterization of mesoporous NaY zeolite from natural Blitar’s kaolin

NASA Astrophysics Data System (ADS)

Khalifah, S. N.; aini, Z. N.; Hayati, E. K.; Aini, N.; Prasetyo, A.

2018-03-01

Mesoporous NaY Zeolite has been synthesized from calcined natural Blitar’s kaolin with the addition of NaOH and CTABr surfactant as mesoporous template by hydrothermal method. Natural kaolin was calcinated with different time and temperature to change kaolin to metakaolin. X-ray diffraction data showed that mesoporous NaY zeolite was formed with impurities compound of sodalite, kaolin and quartz phases. The BET analysis resulted that the pore of NaY Zeolite belongs to mesoporous type with pore size 9,421 nm. Characterization from FTIR confirmed about the functional group of zeolites (988, 776, 663, 464 cm-1). Scanning electron microscopy characterization showed that the morphological of mesoporous NaY zeolites have uniform and crystalline particles formed.

Ion exchangers in radioactive waste management: natural Iranian zeolites.

PubMed

Nilchi, A; Maalek, B; Khanchi, A; Ghanadi Maragheh, M; Bagheri, A; Savoji, K

2006-01-01

Five samples of natural zeolites from different parts of Iran were chosen for this study. In order to characterize and determine their structures, X-ray diffraction and infrared spectrometry were carried out for each sample. The selective absorption properties of each zeolite were found by calculating the distribution coefficient (K(d)) of various simulated wastes which were prepared by spiking the radionuclides with (131)I, (99)Mo, (153)Sm, (140)La and (147)Nd. All the zeolite samples used in this study had extremely high absorption value towards (140)La; clinoptolite from Mianeh and analsite from Ghalehkhargoshi showed good absorption for (147)Nd; clinoptolite from Semnan and clinoptolite from Firozkoh showed high absorption for (153)Sm; mesolite from Arababad Tabas showed good absorption for (99)Mo; and finally mesolite from Arababad Tabas, clinoptolite from Semnan and clinoptolite from Firozkoh could be used to selectively absorb (131)I from the stimulated waste which was prepared. The natural zeolites chosen for these studies show a similar pattern to those synthetic ion exchangers in the literature and in some cases an extremely high selectivity towards certain radioactive elements. Hence the binary separation of radioactive elements could easily be carried out. Furthermore, these zeolites, which are naturally occurring ion exchangers, are viable economically and extremely useful alternatives in this industry.

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.

Performance Evaluations of Ion Exchanged Zeolite Membranes on Alumina Supports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhave, Ramesh R.; Jubin, Robert Thomas; Spencer, Barry B.

2017-08-27

This report describes the synthesis and evaluation of molecular sieve zeolite membranes to separate and concentrate tritiated water (HTO) from dilute HTO-bearing aqueous streams. In the first phase of this effort, several monovalent and divalent cation-exchanged silico alumino phosphate (SAPO-34) molecular sieve zeolite membranes were synthesized on disk supports and characterized with gas and vapor permeation measurements. In the second phase, Linde Type A (LTA) zeolite membranes were synthesized in disk and tubular supports. The pervaporation process performance was evaluated for the separation and concentration of tritiated water.

Isomerization of glucose into fructose by environmentally friendly Fe/β zeolite catalysts.

PubMed

Xu, Siquan; Zhang, Lei; Xiao, Kehao; Xia, Haian

2017-06-29

Herein, the environmentally friendly Fe/β zeolite for glucose isomerization to fructose in aqueous media was reported for the first time. The effects of various reaction conditions including reaction temperature, reaction time, catalyst dosage, etc. on the isomerization reaction over Fe/β zeolite were studied in detail. Under the optimized conditions, yield of fructose higher than 20% were obtained. Moreover, the Fe/β zeolite catalysts were stable and remained constant catalytic activity after five consecutive runs. The possible active Fe species for isomerization of glucose in Fe/β zeolite is also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

NO2 disproportionation for the IR characterisation of basic zeolites.

PubMed

Marie, Olivier; Malicki, Nicolas; Pommier, Catherine; Massiani, Pascale; Vos, Ann; Schoonheydt, Robert; Geerlings, Paul; Henriques, Carlos; Thibault-Starzyk, Fréderic

2005-02-28

NO2 disproportionation on alkaline zeolites is used to generate nitrosonium (NO+) and nitrate ions on the surface, and the infrared vibrations observed are very sensitive to the cation chemical hardness and to the basicity of zeolitic oxygen atoms.

Biodiesel synthesis via transesterification of lipid Chlorophyta cultivated in walne rich carbon medium using KOH/Zeolite catalyst

NASA Astrophysics Data System (ADS)

Dianursanti, Hayati, Siti Zahrotul; Putri, Dwini Normayulisa

2017-11-01

Microalgae from the Chlorophyta division such as Nannochloropsis oculata and Chlorella vulgaris are highly potential to be developed as biodiesel feedstocks because they have a high oil content up to 58%. Biodiesel is produced by transesterification of triglycerides and alcohols with the aid of homogeneous catalysts such as KOH. However, the use of KOH catalysts produces soaps in the biodiesel synthesis. Heterogeneous catalysts are known to solve this problem. One of them is natural zeolite. Zeolite can be used as a catalyst and as a support catalyst. Loading KOH on the zeolite surface is expected to increase alkalinity in KOH/Zeolite catalysts so as to increase the activity of KOH/Zeolite catalyst in transesterification of triglyceride with methanol. In this experimental lipid of microalgae will be used for produced biodiesel via transesterification reaction with methanol and KOH/Zeolite as a catalyst heterogeneous at 60 °C for 3h and utilized catalyst modificated KOH/Zeolite with variation 0.5 M, 1 M and 1.5 M KOH. The modified zeolite was then analyzed by XRF, XRD and BET. The result showed that the yield of biodiesel from lipid N.oculata was 81,09% by 0.5KOH/Zeolite catalyst, 86,53% by 1KOH/Zeolite catalyst, 1,5KOH/Zeolite and 88,13% by 1.5KOH/Zeolit, while the biodiesel produced from lipid C.vulgaris was 59.29% by 0.5KOH/Zeolite, 82.27% by 1KOH/Zeolite and 83.72% by 1.5KOH/Zeolite.

A bioscaffolding strategy for hierarchical zeolites with a nanotube-trimodal network.

PubMed

Li, Guannan; Huang, Haibo; Yu, Bowen; Wang, Yun; Tao, Jiawei; Wei, Yingxu; Li, Shougui; Liu, Zhongmin; Xu, Yan; Xu, Ruren

2016-02-01

Hierarchical zeolite monoliths with multimodal porosity are of paramount importance as they open up new horizons for advanced applications. So far, hierarchical zeolites based on nanotube scaffolds have never been reported. Inspired by the organization of biominerals, we have developed a novel precursor scaffolding-solid phase crystallization strategy for hierarchical zeolites with a unique nanotube scaffolding architecture and nanotube-trimodal network, where biomolecular self-assembly (BSA) provides a scaffolding blueprint. By vapor-treating Sil-1 seeded precursor scaffolds, zeolite MFI nanotube scaffolds are self-generated, during which evolution phenomena such as segmented voids and solid bridges are observed, in agreement with the Kirkendall effect in a solid-phase crystallization system. The nanotube walls are made of intergrown single crystals rendering good mechanical stability. The inner diameter of the nanotube is tunable between 30 and 90 nm by varying the thickness of the precursor layers. Macropores enclosed by cross-linked nanotubes can be modulated by the choice of BSA. Narrow mesopores are formed by intergrown nanocrystals. Hierarchical ZSM-5 monoliths with nanotube (90 nm), micropore (0.55 nm), mesopore (2 nm) and macropore (700 nm) exhibit superior catalytic performance in the methanol-to-hydrocarbon (MTH) conversion compared to conventional ZSM-5. BSA remains intact after crystallization, allowing a higher level of organization and functionalization of the zeolite nanotube scaffolds. The current work may afford a versatile strategy for hierarchical zeolite monoliths with nanotube scaffolding architectures and a nanotube-multimodal network leading to self-supporting and active zeolite catalysts, and for applications beyond.

Potential of sustainable hierarchical zeolites in the valorization of α-pinene.

PubMed

Nuttens, Nicolas; Verboekend, Danny; Deneyer, Aron; Van Aelst, Joost; Sels, Bert F

2015-04-13

In the valorization of α-pinene, which is an important biomass intermediate derived from turpentine oil, hierarchical (mesoporous) zeolites represent a superior class of catalysts. Hierarchical USY, ZSM-5, and beta zeolites have been prepared, characterized, and catalytically evaluated, with the aim of combining the highest catalytic performance with the most sustainable synthetic protocol. These zeolites are prepared by alkaline treatment in aqueous solutions of NH4 OH, NaOH, diethylamine, and NaOH complemented with tetrapropylammonium bromide. The hierarchical USY zeolite is the most attractive catalyst of the tested series, and is able to combine an overall organic-free synthesis with an up to sixfold activity enhancement and comparable selectivity over the conventional USY zeolite. This superior performance relates to a threefold greater activity than that of the commercial standard, namely, H2 SO4 /TiO2 . Correlation of the obtained benefits to the amount of solid lost during the postsynthetic modifications highlights that the highest activity gains are obtained with minor leaching. Furthermore, a highly zeolitic character, as determined by bulk XRD, is beneficial, but not crucial, in the conversion of α-pinene. The alkaline treatments not only result in a higher overall activity, but also a more functional external surface area, attaining up to four times the pinene conversions per square nanometer. The efficiency of the hierarchical USY zeolite is concomitantly demonstrated in the conversion of limonene and turpentine oil, which emphasizes its industrial potential. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of different natural zeolite concentrations on the anaerobic digestion of piggery waste.

PubMed

Milán, Z; Sánchez, E; Weiland, P; Borja, R; Martín, A; Ilangovan, K

2001-10-01

The effect of different natural zeolite concentrations on the anaerobic digestion of piggery waste was studied. Natural zeolite doses in the range 0.2-10 g/l of wastewater were used in batch experiments, which were carried out at temperatures between 27 degrees C and 30 degrees C. Total chemical oxygen demand (COD), total and volatile solids, ammonia and organic nitrogen, pH, total volatile fatty acids (TVFA), alkalinity (Alk) and accumulative methane production were determined during 30 days of digestion. The anaerobic digestion process was favored by the addition of natural zeolite at doses between 2 and 4 g/l and increasingly inhibited at doses beyond 6 g/l. A first-order kinetic model of COD removal was used to determine the apparent kinetic constants of the process. The kinetic constant values increased with the zeolite amount up to a concentration of 4 g/l. The values of the maximum accumulative methane production (Gm) increased until zeolite concentrations of 2-4 g/l. The addition of zeolite reduced the values of the TVFA/ Alk ratio while increasing the pH values, and these facts could contribute to the process failure at zeolite doses of 10 g/l.

A Fiber Optic Interferometric Sensor Platform for Determining Gas Diffusivity in Zeolite Films.

PubMed

Yang, Ruidong; Xu, Zhi; Zeng, Shixuan; Jing, Wenheng; Trontz, Adam; Dong, Junhang

2018-04-04

Fiber optic interferometer (FOI) sensors have been fabricated by directly growing pure-silica MFI-type zeolite (i.e., silicalite) films on straight-cut endfaces of single-mode communication optical fibers. The FOI sensor has been demonstrated for determining molecular diffusivity in the zeolite by monitoring the temporal response of light interference from the zeolite film during the dynamic process of gas adsorption. The optical thickness of the zeolite film depends on the amount of gas adsorption that causes the light interference to shift upon loading molecules into the zeolitic channels. Thus, the time-dependence of the optical signal reflected from the coated zeolite film can represent the adsorption uptake curve, which allows computation of the diffusivity using models derived from the Fick’s Law equations. In this study, the diffusivity of isobutane in silicalite has been determined by the new FOI sensing method, and the results are in good agreement with literature values obtained by various conventional macroscopic techniques. The FOI sensor platform, because of its robustness and small size, could be useful for studying molecular diffusion in zeolitic materials under conditions that are inaccessible to the existing techniques.

Atmospheric Pressure Plasma Jet-Assisted Synthesis of Zeolite-Based Low-k Thin Films.

PubMed

Huang, Kai-Yu; Chi, Heng-Yu; Kao, Peng-Kai; Huang, Fei-Hung; Jian, Qi-Ming; Cheng, I-Chun; Lee, Wen-Ya; Hsu, Cheng-Che; Kang, Dun-Yen

2018-01-10

Zeolites are ideal low-dielectric constant (low-k) materials. This paper reports on a novel plasma-assisted approach to the synthesis of low-k thin films comprising pure-silica zeolite MFI. The proposed method involves treating the aged solution using an atmospheric pressure plasma jet (APPJ). The high reactivity of the resulting nitrogen plasma helps to produce zeolite crystals with high crystallinity and uniform crystal size distribution. The APPJ treatment also remarkably reduces the time for hydrothermal reaction. The zeolite MFI suspensions synthesized with the APPJ treatment are used for the wet deposition to form thin films. The deposited zeolite thin films possessed dense morphology and high crystallinity, which overcome the trade-off between crystallinity and film quality. Zeolite thin films synthesized using the proposed APPJ treatment achieve low leakage current (on the order of 10 -8 A/cm 2 ) and high Young's modulus (12 GPa), outperforming the control sample synthesized without plasma treatment. The dielectric constant of our zeolite thin films was as low as 1.41. The overall performance of the low-k thin films synthesized with the APPJ treatment far exceed existing low-k films comprising pure-silica MFI.

Application of natural zeolite for phosphorus and ammonium removal from aqueous solutions.

PubMed

Karapinar, Nuray

2009-10-30

Removal of both nutrients ammonium and phosphorus by natural zeolite has been studied in lab scale by using a mechanically stirred batch system (1000 ml). Zeolite, a mean particle size of 13 microm, was used as an adsorbent for the removal of ammonium and then as a seed material for the precipitation of calcium phosphate. A relationship was established between the uptake of ammonium by zeolite and the ratio of initial ammonium concentration to zeolite dosage. Ammonium uptake of zeolite was almost completed within initial 5 min of adsorption period. There is no pronounced effect of zeolite and ammonium, neither positive nor negative on the amount of calcium phosphate precipitation. The extent of the precipitation of phosphate increased with rising pH. It was also observed that when the system was allowed to relax at constant pH (i.e. under relatively low super saturations), a certain lag time was noted to elapse at the onset of the precipitation. At the pH 7.2, the amount of initial fast precipitation within 5 min and total precipitation within 120 min were around 34% and 93%, respectively. Precipitation of calcium phosphate on to ammonium-loaded zeolite was achieved at low super saturations (< pH 7.5) through secondary nucleation and crystal growth, leading to an increase in particle size.

Halloysite nanotube-based electrospun ceramic nanofibre mat: a novel support for zeolite membranes

PubMed Central

Chen, Zhuwen; Zeng, Jiaying; Lv, Dong; Gao, Jinqiang; Zhang, Jian; Bai, Shan; Li, Ruili; Wu, Jingshen

2016-01-01

Some key parameters of supports such as porosity, pore shape and size are of great importance for fabrication and performance of zeolite membranes. In this study, we fabricated millimetre-thick, self-standing electrospun ceramic nanofibre mats and employed them as a novel support for zeolite membranes. The nanofibre mats were prepared by electrospinning a halloysite nanotubes/polyvinyl pyrrolidone composite followed by a programmed sintering process. The interwoven nanofibre mats possess up to 80% porosity, narrow pore size distribution, low pore tortuosity and highly interconnected pore structure. Compared with the commercial α-Al2O3 supports prepared by powder compaction and sintering, the halloysite nanotube-based mats (HNMs) show higher flux, better adsorption of zeolite seeds, adhesion of zeolite membranes and lower Al leaching. Four types of zeolite membranes supported on HNMs have been successfully synthesized with either in situ crystallization or a secondary growth method, demonstrating good universality of HNMs for supporting zeolite membranes. PMID:28083098

Investigation of mircroorganisms colonising activated zeolites during anaerobic biogas production from grass silage.

PubMed

Weiss, S; Zankel, A; Lebuhn, M; Petrak, S; Somitsch, W; Guebitz, G M

2011-03-01

The colonisation of activated zeolites (i.e. clinoptilolites) as carriers for microorganisms involved in the biogas process was investigated. Zeolite particle sizes of 1.0-2.5mm were introduced to anaerobic laboratory batch-cultures and to continuously operated bioreactors during biogas production from grass silage. Incubation over 5-84 days led to the colonisation of zeolite surfaces in small batch-cultures (500 ml) and even in larger scaled and flow-through disturbed bioreactors (28 l). Morphological insights were obtained by using scanning electron microscopy (SEM). Single strand conformation polymorphism (SSCP) analysis based on amplification of bacterial and archaeal 16S rRNA fragments demonstrated structurally distinct populations preferring zeolite as operational environment. via sequence analysis conspicuous bands from SSCP patterns were identified. Populations immobilised on zeolite (e.g. Ruminofilibacter xylanolyticum) showed pronounced hydrolytic enzyme activity (xylanase) shortly after re-incubation in sterilised sludge on model substrate. In addition, the presence of methanogenic archaea on zeolite particles was demonstrated. Copyright © 2010 Elsevier Ltd. All rights reserved.

Halloysite nanotube-based electrospun ceramic nanofibre mat: a novel support for zeolite membranes

NASA Astrophysics Data System (ADS)

Chen, Zhuwen; Zeng, Jiaying; Lv, Dong; Gao, Jinqiang; Zhang, Jian; Bai, Shan; Li, Ruili; Hong, Mei; Wu, Jingshen

2016-12-01

Some key parameters of supports such as porosity, pore shape and size are of great importance for fabrication and performance of zeolite membranes. In this study, we fabricated millimetre-thick, self-standing electrospun ceramic nanofibre mats and employed them as a novel support for zeolite membranes. The nanofibre mats were prepared by electrospinning a halloysite nanotubes/polyvinyl pyrrolidone composite followed by a programmed sintering process. The interwoven nanofibre mats possess up to 80% porosity, narrow pore size distribution, low pore tortuosity and highly interconnected pore structure. Compared with the commercial α-Al2O3 supports prepared by powder compaction and sintering, the halloysite nanotube-based mats (HNMs) show higher flux, better adsorption of zeolite seeds, adhesion of zeolite membranes and lower Al leaching. Four types of zeolite membranes supported on HNMs have been successfully synthesized with either in situ crystallization or a secondary growth method, demonstrating good universality of HNMs for supporting zeolite membranes.

Endovascular treatment of occluded and stenotic visceral vessels in patients with chronic mesenteric ischemia.

PubMed

Christofi, Georgia; Donas, Konstantinos P; Pitoulias, Georgios A; Torsello, Giovanni; Schwindt, Arne G; Stavroulakis, Konstantinos

2017-02-01

Objective Current evidence in the literature about endovascular treatment (ET) of visceral vessels in patients with chronic mesenterial ischemia (CMI) based on morphological characteristics is limited. The aim of this study was the evaluation of ET in occluded and stenotic visceral vessels. Methods Patients undergoing ET for CMI between November 2000 and November 2012 were included in this retrospective study. Primary measure outcome was the symptom-free survival (SFS). Secondary outcomes were primary (PPR), secondary patency (SPR) rates and technical success rate (TSR). A Cox-regression analysis identified risk factors for the primary and secondary measure outcomes. Results Forty patients were included in the present study (men: 21, mean age: 68). The overall number of vessels with intention-to-treat was 62. Fifty-two visceral arteries (18 occlusions and 34 stenoses) were successfully treated by endovascular means. The overall TSR was 84%. Visceral vessel occlusions and atherosclerotic disease of the superior mesenteric artery (SMA) were identified as independent risk factors for poorer TSR ( p < 0.05). The 12-month SFS was 60%. The overall 12-month PPR and SPR were 71% and 94%, respectively. No significant differences were observed between occluded and stenotic vessels ( p > 0.05) concerning the PPR. On the other hand, the subgroup analysis revealed higher SPR among occluded visceral vessels ( p < 0.001) and coeliac axis lesions ( p < 0.001). Conclusions ET was associated with high incidence of symptoms recurrence despite the satisfying patency rates in both occluded and stenotic vessels. Additionally, visceral vessel occlusion and presence of atherosclerotic lesions in the SMA were associated with poorer TSR.

Experiment 3: Zeolite Crystal Growth in Microgravity- The USML-2 Mission

NASA Technical Reports Server (NTRS)

Bac, Nurcan; Warzywoda, Juliusz; Sacco, Albert, Jr.

1998-01-01

The extensive use of zeolites and their impact on the world's economy leads to many efforts to characterize their structure, and to improve the knowledge base for nucleation and growth of these crystals. The Zeolite Crystal Growth (ZCG) experiment on USML-2 aims to enhance the understanding of nucleation and growth of zeolite crystals while attempting to provide a means of controlling the defect concentration in microgravity. Zeolites A, X, Beta, and Silicalite were grown during the 16-day USML-2 mission. The solutions where the nucleation event was controlled yielded larger and more uniform crystals of better morphology and purity than their terrestrial/control counterparts. Space-grown Beta crystals were free of line defects while terrestrial/controls had substantial defects.

Zeolite catalysis in the synthesis of isobutylene from hydrous ethanol

NASA Astrophysics Data System (ADS)

Phillips, Cory Bernard

1999-11-01

This work deals with the synthesis of isobutylene from a hydrous ethanol feedstock over zeolites. The synthesis is accomplished in three steps: (1) low-temperature direct ethanol conversion to ethylene on H-ZSM-5 zeolite, (2) ethylene conversion to butene products over metal-exchanged zeolites, and (3) butene skeletal rearrangement to isobutylene over FER zeolites. The key to understanding and optimizing each synthesis step lies in the ability to control and regulate the zeolite acidity (Bronsted and Lewis)---both strength and number. Therefore, the continuous temperature programmed amine desorption (CTPAD) technique was further developed to simultaneously count the Bronsted acid sites and quantitatively characterize their strength. The adsorption of ethanol, reaction products, amines, coke and ethanol-derived residue (EDR) were monitored gravimetrically using the highly sensitive, novel Tapered Element Oscillating Microreactor (TEOM) apparatus. The TEOM was also used also in conjunction with CTPAD to characterize Bronsted acidity which is a new application for the instrument. For the first synthesis step, a parallel reaction exists which simultaneously produces diethyl ether and ethylene directly over H-ZSM-5. The reaction rates for each pathway were measured directly using a differential reactor operating at low temperatures (<473 K). Water in the ethanol feed enhances the rate of ethylene formation. A mechanism and kinetic expression are proposed for this reaction over H-ZSM-5, with diethyl-ether desorption and ethylene formation as the rate limiting steps. Heat of adsorption values measured from the independent microcalorimetry work reported in the literature are incorporated into the kinetic analysis which reduces the number of regressed parameters. For the remaining synthesis steps, several zeolite structures (ZSM-5, Y, FER) partially exchanged with Pd, Ti, Ni and Au were prepared and tested. It was determined from this screening study that the zeolites

Crewmember working on the mid deck Zeolite Crystal Growth experiment.

NASA Technical Reports Server (NTRS)

1992-01-01

View showing Payload Specialist Bonnie Dunbar, in the mid deck, conducting the Zeolite Crystal Growth (ZCG) Experiment in the mid deck stowage locker work area. View shows assembly of zeolite sample in the metal autoclave cylinders prior to insertion into the furnace.

Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations.

PubMed

Oleksiak, Matthew D; Ghorbanpour, Arian; Conato, Marlon T; McGrail, B Peter; Grabow, Lars C; Motkuri, Radha Kishan; Rimer, Jeffrey D

2016-11-02

Designing zeolites with tunable physicochemical properties can substantially impact their performance in commercial applications, such as adsorption, separations, catalysis, and drug delivery. Zeolite synthesis typically requires an organic structure-directing agent to produce crystals with specific pore topology. Attempts to remove organics from syntheses to achieve commercially viable methods of preparing zeolites often lead to the formation of impurities. Herein, we present organic-free syntheses of two polymorphs of the small-pore zeolite P (GIS), P1 and P2. Using a combination of adsorption measurements and density functional theory calculations, we show that GIS polymorphs are selective adsorbents for H 2 O relative to other light gases (e.g., H 2 , N 2 , CO 2 ). Our findings refute prior theoretical studies postulating that GIS-type zeolites are excellent materials for CO 2 separation/sequestration. We also show that P2 is significantly more thermally stable than P1, which broadens the operating conditions for GIS-type zeolites in commercial applications and opens new avenues for exploring their potential use in processes such as catalysis. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal Properties of Zeolite-Containing Composites

PubMed Central

Shimonosono, Taro; Hirata, Yoshihiro; Nishikawa, Kyohei; Sameshima, Soichiro; Sodeyama, Kenichi; Masunaga, Takuro; Yoshimura, Yukio

2018-01-01

A zeolite (mordenite)–pore–phenol resin composite and a zeolite–pore–shirasu glass composite were fabricated by hot-pressing. Their thermal conductivities were measured by a laser flash method to determine the thermal conductivity of the monolithic zeolite with the proposed mixing rule. The analysis using composites is useful for a zeolite powder with no sinterability to clarify its thermal properties. At a low porosity <20%, the thermal conductivity of the composite was in excellent agreement with the calculated value for the structure with phenol resin or shirasu glass continuous phase. At a higher porosity above 40%, the measured value approached the calculated value for the structure with pore continuous phase. The thermal conductivity of the monolithic mordenite was evaluated to be 3.63 W/mK and 1.70–2.07 W/mK at room temperature for the zeolite–pore–phenol resin composite and the zeolite–pore–shirasu glass composite, respectively. The analyzed thermal conductivities of monolithic mordenite showed a minimum value of 1.23 W/mK at 400 °C and increased to 2.51 W/mK at 800 °C. PMID:29534034

Applicability of Zeolite Based Systems for Ammonia Removal and Recovery From Wastewater.

PubMed

Das, Pallabi; Prasad, Bably; Singh, Krishna Kant Kumar

2017-09-01

  Ammonia discharged in industrial effluents bears deleterious effects and necessitates remediation. Integrated systems devoted to recovery of ammonia in a useful form and remediation of the same addresses the challenges of waste management and its utilization. A comparative performance evaluation study was undertaken to access the suitability of different zeolite based systems (commercial zeolites and zeolites synthesized from fly ash) for removal of ammonia followed by its subsequent release. Four main parameters which were studied to evaluate the applicability of such systems for large scale usage are cost-effectiveness, ammonia removal efficiency, performance on regeneration, and ammonia release percentage. The results indicated that synthetic zeolites outperformed zeolites synthesized from fly ash, although the later proved to be more efficient in terms of total cost incurred. Process technology development in this direction will be a trade-of between cost and ammonia removal and release efficiencies.

Palladium-Zeolite nanofiber as an effective recyclable catalyst membrane for water treatment.

PubMed

Choi, Jungsu; Chan, Sophia; Yip, Garriott; Joo, Hyunjong; Yang, Heejae; Ko, Frank K

2016-09-15

Zeolite is an exciting natural material due to its unique capability of ammonium nitrogen (NH3N) adsorption in water. In this study, multifunctional hybrid composites of zeolite/palladium (Ze/Pd) on polymer nanofiber membranes were fabricated and explored for sustainable contaminant removal. SEM and XRD demonstrated that zeolite and palladium nanoparticles were uniformly distributed and deposited on the nanofibers. NH3N recovery rate was increased from 23 to 92% when palladium coated zeolite was embedded on the nanofiber. Multifunctional nanofibers of Ze/Pd membranes were able to adsorb NH3N on the zeolites placed on the surface of fibers and palladium catalysts were capable of selective oxidation of NH3N to N2 gas. The cycling of NH3N adsorption-oxidation, high flux, hydrophilicity, and flexibility of the membrane makes it a strong candidate for water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Co-remediation of the lead-polluted garden soil by exogenous natural zeolite and humic acids.

PubMed

Shi, Wei-yu; Shao, Hong-bo; Li, Hua; Shao, Ming-an; Du, Sheng

2009-08-15

The current study reported the co-remediation effect on the lead-polluted garden soil by zeolite and humic acids (HA), which was from comparing with the remediation of single zeolite in term of the lead fraction of sequential extraction in the soil and the distribution of lead in different parts of rape. Mixed treatment (zeolite and HA) and single treatment (zeolite) were, respectively, applied to the artificially polluted garden soil to examine the difference of their remediation effects in pot experiment. Results indicated that the co-remediation led to significantly greater (p<0.01) reduction in the lead concentration in plants than by singly adding to zeolite. The co-application of zeolite and HA reduced the available fraction of lead compounds, but slightly increased (p<0.01) the water-soluble fraction of lead compounds in the garden soil, compared with the application of single zeolite, especially in the severe lead-polluted soil (> or =1000 mg kg(-1)). This method might be an efficient way to remediate the lead-polluted soils on a large scale, although zeolite is a kind of hazardous material.

Transformation of Indonesian Natural Zeolite into Analcime Phase under Hydrothermal Condition

NASA Astrophysics Data System (ADS)

Lestari, W. W.; Hasanah, D. N.; Putra, R.; Mukti, R. R.; Nugrahaningtyas, K. D.

2018-04-01

Natural zeolite is abundantly available in Indonesia and well distributed especially in the volcano area like Java, Sumatera, and Sulawesi. So far, natural zeolite from Klaten, Central Java is one of the most interesting zeolites has been widely studied. This research aims to know the effect of seed-assisted synthesis under a hydrothermal condition at 120 °C for 24 hours of Klaten’s zeolite toward the structural change and phase transformation of the original structure. According to XRD and XRF analysis, seed-assisted synthesis through the addition of aluminosilicate mother solution has transformed Klaten’s zeolite which contains (mordenite and clinoptilolite) into analcime type with decreasing Si/Al ratio from 4.51 into 1.38. Morphological analysis using SEM showed the shape changes from irregular into spherical looks like takraw ball in the range of 0.3 to 0.7 micrometer. Based on FTIR data, structure of TO4 site (T = Si or Al) was observed in the range of 300-1300 cm-1 and the occupancy of Brønsted acid site as OH stretching band from silanol groups was detected at 3440-3650 cm-1. Nitrogen adsorption-desorption analysis confirmed that transformation Klaten’s zeolite into analcime type has decreased the surface area from 55.41 to 22.89 m2/g and showed inhomogeneous pore distribution which can be classified as micro-mesoporous aluminosilicate materials.

Diffusion of aromatic hydrocarbons in hierarchical mesoporous H-ZSM-5 zeolite

DOE PAGES

Bu, Lintao; Nimlos, Mark R.; Robichaud, David J.; ...

2018-02-08

Hierarchical mesoporous zeolites exhibit higher catalytic activities and longer lifetime compared to the traditional microporous zeolites due to improved diffusivity of substrate molecules and their enhanced access to the zeolite active sites. Understanding diffusion of biomass pyrolysis vapors and their upgraded products in such materials is fundamentally important during catalytic fast pyrolysis (CFP) of lignocellulosic biomass, since diffusion makes major contribution to determine shape selectivity and product distribution. However, diffusivities of biomass relevant species in hierarchical mesoporous zeolites are poorly characterized, primarily due to the limitations of the available experimental technology. In this work, molecular dynamics (MD) simulations are utilizedmore » to investigate the diffusivities of several selected coke precursor molecules, benzene, naphthalene, and anthracene, in hierarchical mesoporous H-ZSM-5 zeolite. The effects of temperature and size of mesopores on the diffusivity of the chosen model compounds are examined. The simulation results demonstrate that diffusion within the microspores as well as on the external surface of mesoporous H-ZSM-5 dominates only at low temperature. At pyrolysis relevant temperatures, mass transfer is essentially conducted via diffusion along the mesopores. Additionally, the results illustrate the heuristic diffusion model, such as the extensively used Knudsen diffusion, overestimates the diffusion of bulky molecules in the mesopores, thus making MD simulation a powerful and compulsory approach to explore diffusion in zeolites.« less

Highly crystallized nanometer-sized zeolite a with large Cs adsorption capability for the decontamination of water.

PubMed

Torad, Nagy L; Naito, Masanobu; Tatami, Junichi; Endo, Akira; Leo, Sin-Yen; Ishihara, Shinsuke; Wu, Kevin C-W; Wakihara, Toru; Yamauchi, Yusuke

2014-03-01

Nanometer-sized zeolite A with a large cesium (Cs) uptake capability is prepared through a simple post-milling recrystallization method. This method is suitable for producing nanometer-sized zeolite in large scale, as additional organic compounds are not needed to control zeolite nucleation and crystal growth. Herein, we perform a quartz crystal microbalance (QCM) study to evaluate the uptake ability of Cs ions by zeolite, to the best of our knowledge, for the first time. In comparison to micrometer-sized zeolite A, nanometer-sized zeolite A can rapidly accommodate a larger amount of Cs ions into the zeolite crystal structure, owing to its high external surface area. Nanometer-sized zeolite is a promising candidate for the removal of radioactive Cs ions from polluted water. Our QCM study on Cs adsorption uptake behavior provides the information of adsorption kinetics (e.g., adsorption amounts and rates). This technique is applicable to other zeolites, which will be highly valuable for further consideration of radioactive Cs removal in the future. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Potential of Ni supported on KH zeolite catalysts for carbon dioxide reforming of methane

NASA Astrophysics Data System (ADS)

Kaengsilalai, Athiya; Luengnaruemitchai, Apanee; Jitkarnka, Sirirat; Wongkasemjit, Sujitra

The catalytic activity of Ni on a series of catalysts supported on the synthesized KH zeolite for the CO 2 reforming of methane has been investigated. The KH zeolite supports were previously synthesized via silatrane and alumatrane precursors using the sol-gel process and hydrothermal microwave treatment. Eight percent Ni was impregnated onto the synthesized KH zeolites, which have different morphologies: called dog-bone, flower, and disordered shapes. The prepared Ni/KH zeolites were tested for their catalytic activity at 700 °C, at atmospheric pressure, and at a CH 4/CO 2 ratio of 1. The results showed that Ni supported on dog-bone and flower-shaped KH zeolites provided better activity than that of disordered KH zeolite due to higher CH 4 and CO 2 conversions, a higher H 2 production, and a smaller amount of coke formation on the catalyst surface. Furthermore, the stability of the Ni/KH zeolite was greatly superior to that of Ni supported on alumina and clinoptiolite catalysts after 65 h on stream.

[Preparation of HDTMA-modified Zeolite and Its Performance in Nitro-phenol Adsorption from Wastewaters].

PubMed

Guo, Jun-yuan; Wang, Bin

2016-05-15

In this study, natural zeolite was modified by HDTMA. Effects of the modified conditions, HDTMA-modified zeolite doses, solution pH values, and reaction time on nitro-phenol removal were investigated, and the adsorption kinetics and isotherms were discussed. Compared with natural zeolite, HDTMA-modified zeolite showed better performance in nitro-phenol removal. An adsorption capacity of 2.53 mg · g⁻¹ was achieved when the concentration of HDTMA solution (pH = 10) was 1.2% in preparation of modified zeolite. This adsorption capacity was higher than that obtained by natural zeolite (0.54 mg · g⁻¹). In adsorption tests, when HDTMA- modified zeolite dose was adjusted to 8 g · L⁻¹, the removal efficiency of nitro-phenol reached 93.9% after 90 min reaction, with wastewater pH of 6. Furthermore, the nitro-phenol adsorption process could be well fitted to the pseudo-first-order kinetics model (R² > 0.90), whereas the adsorption isotherm results indicated that Langmuir model provided the best fitting for the equilibrium data at different temperatures, with R² of higher than 0.90.

Transcatheter closure of left ventricle to right atrial communication using cera duct occluder.

PubMed

Ganesan, Gnanavelu; Paul, G Justin; Mahadevan, Vaikom S

Left ventricle-right atrial communication could be congenital (Gerbode defect) or acquired as a complication of surgery or infective endocarditis and leads to volume overloading of pulmonary circulation. Two types, direct and indirect types are known depending on the involvement of septal tricuspid leaflet. Transcatheter closure of this defect is feasible and appears an attractive alternative to surgical management. Various devices like Amplatzer duct occluder I, II, Muscular ventricular septal defect device etc. have been used to close this defect. We report two patients, a preteen boy with direct left ventricle-right atrial communication as post operative complication and an adult female with indirect communication who underwent transcatheter closure with Cera duct occluder (Lifetech Scientific (Shenzhen), China). Copyright © 2017. Published by Elsevier B.V.

Mobil/Badger to market zeolite-based cumene technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rotman, D.

1993-02-24

Badger (Cambridge, MA) and Mobil (Fairfax, VA) are ready to jointly license a new cumene technology that they say achieves higher yields and product purity than existing processes. The zeolite-based technology is scheduled to be introduced at next month's DeWitt Petrochemical Review in Houston. The Mobil/Badger technology aims to challenge the dominant position of UOP's (Des Plaines, IL) solid phosphoric acid (SPA) catalyst process - which accounts for 80%-90% of the world's cumene production. In addition, Monsanto/Kellogg's aluminum chloride-based technology has gained significant momentum since its introduction in the 1980s. And late last year, ABB Lummus Crest (Bloomfield, NJ) alsomore » began marketing a zeolite-based cumene technology. While all the technologies make cumene via the alkylation of benzene with propylene, the Mobil/Badger process uses a zeolite-containing catalyst designed by Mobil to selectively catalyze the benzene/propylene reaction, avoiding unwanted propylene oligomerization. Because the olefin reactions are so fast, says Frank A. Demers, Badger's v.p./technology development and marketing, other zeolite technologies are forced to use complex reactor arrangements to stop the propylene-propylene reactions. However, he says, Mobil has designed a catalyst that wants to react benzene with propylene to make cumene.'« less

Simulation of Water Gas Shift Zeolite Membrane Reactor

NASA Astrophysics Data System (ADS)

Makertiharta, I. G. B. N.; Rizki, Z.; Zunita, Megawati; Dharmawijaya, P. T.

2017-07-01

The search of alternative energy sources keeps growing from time to time. Various alternatives have been introduced to reduce the use of fossil fuel, including hydrogen. Many pathways can be used to produce hydrogen. Among all of those, the Water Gas Shift (WGS) reaction is the most common pathway to produce high purity hydrogen. The WGS technique faces a downstream processing challenge due to the removal hydrogen from the product stream itself since it contains a mixture of hydrogen, carbon dioxide and also the excess reactants. An integrated process using zeolite membrane reactor has been introduced to improve the performance of the process by selectively separate the hydrogen whilst boosting the conversion. Furthermore, the zeolite membrane reactor can be further improved via optimizing the process condition. This paper discusses the simulation of Zeolite Membrane Water Gas Shift Reactor (ZMWGSR) with variation of process condition to achieve an optimum performance. The simulation can be simulated into two consecutive mechanisms, the reaction prior to the permeation of gases through the zeolite membrane. This paper is focused on the optimization of the process parameters (e.g. temperature, initial concentration) and also membrane properties (e.g. pore size) to achieve an optimum product specification (concentration, purity).

High-pressure alchemy on a small-pore zeolite

NASA Astrophysics Data System (ADS)

Lee, Y.

2011-12-01

While an ever-expanding variety of zeolites with a wide range of framework topology is available, it is desirable to have a way to tailor the chemistry of the zeolitic nanopores for a given framework topology via controlling both the coordination-inclusion chemistry and framework distortion/relaxation. This is, however, subjected to the ability of a zeolitic nanopore to allow the redistribution of cations-water assembly and/or insertion of foreign molecules into the pores and channels. Small-pore zeolites such as natrolite (Na16Al16Si24O80x16H2O), however, have been known to show very limited capacity for any changes in the confinement chemistry. We have recently shown that various cation-exchanged natrolites can be prepared under modest conditions from natural sodium natrolite and exhibit cation-dependent volume expansions by up to 18.5% via converting the elliptical channels into progressively circular ones. Here, we show that pressure can be used as a unique and clean tool to further manipulate the chemistry of the natrolite nanopores. Our recent crystallographic and spectroscopic studies of pressure-insertion of foreign molecules, trivalent-cation exchange under pressure, and pressure-induced inversion of cation-water coordination and pore geometry in various cation-exchanged natrolites will be presented.

Characterization of modified zeolite as microbial immobilization media on POME anaerobic digestion

NASA Astrophysics Data System (ADS)

Cahyono, Rochim B.; Ismiyati, Sri; Ginting, Simparmin Br; Mellyanawaty, Melly; Budhijanto, Wiratni

2018-03-01

As the world’s biggest palm oil producer, Indonesia generates also huge amount of Palm Oil Mill Effluent (POME) wastewater and causes serious problem in environment. In conventional method, POME was converted into biogas using lagoon system which required extensive land area. Anaerobic Fluidized Bed Reactor (AFBR) proposes more effective biogas producing with smaller land area. In the proposed system, a immobilization media would be main factor for enhancing productivity. This research studied on characterization of Lampung natural zeolite as immobilization media in the AFBR system for POME treatment. Various activation method such as physical and chemical were attempted to create more suitable material which has larger surface area, pore size distribution as well as excellent surface structures. The physical method was applied by heating up the material till 400°C while HCl was used on the chemical activation. Based on the result, the chemical activation increased the surface area significantly into 71 m2/g compared to physical as well as original zeolite. The strong acid material was quite effective to enforce the impurities within zeolite pore structure compared to heating up the material. According to distribution data, the Lampung zeolite owned the pore size with the range of 3 – 5 μm which was mesopore material. The pore size was appropriate for immobilization media as it was smaller than size of biogas microbial. The XRD patterns verified that chemical activation could maintain the zeolite structure as the original. Obviously, the SEM photograph showed apparent structure and pore size on the modified zeolite using chemical method. The testing of modified zeolite on the batch system was done to evaluate the characterization process. The modified zeolite using chemical process resulted fast reduction of COD and stabilized the volatile fatty acid as the intermediate product of anaerobic digestion, especially in the beginning of the process. Therefore, the

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2014 CFR

2014-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2012 CFR

2012-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2010 CFR

2010-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2011 CFR

2011-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2013 CFR

2013-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

Intuitive physical reasoning about occluded objects by inexperienced chicks

PubMed Central

Chiandetti, Cinzia; Vallortigara, Giorgio

2011-01-01

Questions concerning the role of nature and nurture in higher cognition appear to be intractable if one restricts one's attention to development in humans. However, in other domains, such as sensory development, much information has been gained from controlled rearing studies with animals. Here, we used a similar experimental strategy to investigate intuitive reasoning about occluded objects. Newborn domestic chicks (Gallus gallus) were reared singly with a small object that became their social partner. They were then accustomed to rejoin such an imprinting object when it was made to move and disappear behind either one of two identical opaque screens. After disappearance of the imprinting object, chicks were faced with two screens of different slants, or of different height or different width, which may or may not have been compatible with the presence of the imprinting object hidden beneath/behind them. Chicks consistently chose the screen of slant/height/width compatible with the presence of the object beneath/behind it. Preventing chicks from touching and pecking at the imprinting object before testing did not affect the results, suggesting that intuitive reasoning about physical objects is largely independent of specific experience of interaction with objects and of objects' occluding events. PMID:21270036

Energetics of alkali and alkaline earth ion-exchanged zeolite A

DOE PAGES

Sun, Hui; Wu, Di; Liu, Kefeng; ...

2016-06-30

Alkali and alkaline earth ion-exchanged zeolite A samples were synthesized in aqueous exchange media. They were thoroughly studied by powder X-ray diffraction (XRD), electron microprobe (EMPA), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), and high temperature oxide melt solution calorimetry. The hydration energetics and enthalpies of formation of these zeolite A materials from constituent oxides were determined. Specifically, the hydration level of zeolite A has a linear dependence on the average ionic potential ( Z/r) of the cation, from 0.894 (Rb-A) to 1.317 per TO 2 (Mg-A). The formation enthalpies from oxides (25 °C) range from –93.71 ± 1.77 (K-A)more » to –48.02 ± 1.85 kJ/mol per TO 2 (Li-A) for hydrated alkali ion-exchanged zeolite A, and from –47.99 ± 1.20 (Ba-A) to –26.41 ± 1.71 kJ/mol per TO 2 (Mg-A) for hydrated alkaline earth ion-exchanged zeolite A. As a result, the formation enthalpy from oxides generally becomes less exothermic as Z/r increases, but a distinct difference in slope is observed between the alkali and the alkaline earth series.« less

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.

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.

Hydrothermal fabrication of ZSM-5 zeolites: biocompatibility, drug delivery property, and bactericidal property.

PubMed

Guo, Ya-Ping; Long, Teng; Song, Zhen-Fu; Zhu, Zhen-An

2014-04-01

The bone graft-associated infection is widely considered in orthopedic surgery, which may lead to implant failure, extensive bone debridement, and increased patient morbidity. In this study, we fabricated ZSM-5 zeolites for drug delivery systems by hydrothermal method. The structure, morphology, biocompatibility, drug delivery property, and bactericidal property of the ZSM-5 zeolites were investigated. The ZSM-5 zeolites have mordenite framework inverted-type structure and exhibit the disk-like shape with the diameter of ∼350 nm and thickness of ∼165 nm. The biocompatibility tests indicate that human bone marrow stromal cells spread out well on the surfaces of the ZSM-5 zeolites and proliferate significantly with increasing culture time. As compared with the conventional hydroxyapatite particles, the ZSM-5 zeolites possess greater drug loading efficiency and drug sustained release property because of the ordered micropores, large Brunauer-Emmett-Teller (BET) surface areas, and functional groups. For the gentamicin-loaded ZSM-5 zeolites, the sustained release of gentamicin minimizes significantly bacterial adhesion and prevents biofilm formation against Staphylococcus epidermidis. The excellent biocompatibility, drug delivery property, and bactericidal property of the ZSM-5 zeolites suggest that they have great application potentials for treating implant-associated infections. Copyright © 2013 Wiley Periodicals, Inc.

Characterization of sonicated natural zeolite/ferric chloride hexahydrate by infrared spectroscopy

NASA Astrophysics Data System (ADS)

Prasetyo, T. A. B.; Soegijono, B.

2018-03-01

The characteristics of sonicated Bayah natural zeolite with and without ferric chloride hexahydrate solution using infrared method has been studied. High intensity ultrasonic waves were exposed to the samples for 40 min, 80 min and 120 min. Infra red spectra analysis was conducted to evaluate zeolite vibrational spectrum contributions, namely, the vibrations from the framework of the zeolite, from the charge-balancing cations, and from the relatively isolated groups, such as the surface OH groups and their behavior after sonication process. An addition of FeCl3.6H2O and sonication process on natural zeolite improved secondary building units link by forming oxygen bridges and also close relationship with duration of applied high intensity ultrasonic process. Longer ultrasonic process resulted in more increment of O-H absorbance.

Characterization and Activation of Indonesian Natural Zeolite from Southwest Aceh District-Aceh Province

NASA Astrophysics Data System (ADS)

Yulianis, Y.; Muhammad, S.; Pontas, K.; Mariana, M.; Mahidin, M.

2018-05-01

This study aims to identify the effect of activation processes of Indonesian zeolite from Southwest Aceh District, Aceh Province on the physical characteristics and chemical contents changes. The work was conducted by downsizing of natural zeolite into nano particle size, treating it physically (heated up to 105˚C) and chemically (soaked with 0.5 M HCl for 1 hour), and finally calcining it at the temperature of 350° C for 2 hours. The natural and activated nano zeolites were then characterized by using SEM, BET, XRD, XRF and FTIR in order to examine their characters and chemical contents. The characterization results showed that the activated nano zeolite has better appearances than the natural one. The XRD analysis showed that the main minerals of zeolite are quartz and calcite clinochlore. Further, the XRF analysis showed that there are elements of magnesium, calcium and potassium which can be as a cation exchange with other metal elements. Based on the identified properties, this zeolite showed a good performance to be used as an adsorbent in waste water treatment process, especially after activated.

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

DNA unwinding by ring-shaped T4 helicase gp41 is hindered by tension on the occluded strand.

PubMed

Ribeck, Noah; Saleh, Omar A

2013-01-01

The replicative helicase for bacteriophage T4 is gp41, which is a ring-shaped hexameric motor protein that achieves unwinding of dsDNA by translocating along one strand of ssDNA while forcing the opposite strand to the outside of the ring. While much study has been dedicated to the mechanism of binding and translocation along the ssDNA strand encircled by ring-shaped helicases, relatively little is known about the nature of the interaction with the opposite, 'occluded' strand. Here, we investigate the interplay between the bacteriophage T4 helicase gp41 and the ss/dsDNA fork by measuring, at the single-molecule level, DNA unwinding events on stretched DNA tethers in multiple geometries. We find that gp41 activity is significantly dependent on the geometry and tension of the occluded strand, suggesting an interaction between gp41 and the occluded strand that stimulates the helicase. However, the geometry dependence of gp41 activity is the opposite of that found previously for the E. coli hexameric helicase DnaB. Namely, tension applied between the occluded strand and dsDNA stem inhibits unwinding activity by gp41, while tension pulling apart the two ssDNA tails does not hinder its activity. This implies a distinct variation in helicase-occluded strand interactions among superfamily IV helicases, and we propose a speculative model for this interaction that is consistent with both the data presented here on gp41 and the data that had been previously reported for DnaB.

[The mutagenic action of the dust of natural zeolites and chrysotile asbestos].

PubMed

Durnev, A D; Suslova, T B; Cheremisina, Z P; Dubovskaia, O Iu; Nigarova, E A; Korkina, L G; Seredenin, S B; Velichkovskiĭ, B T

1990-01-01

The cell chemiluminescence method was used to demonstrate the ability of asbest and zeolite dusts from 8 deposits of the USSR to induce generation of free oxygen radicals in the phagocytosing cells suspension. It has been found that asbest and zeolite (0.01 and 0.05 mg/ml) increase levels of cells with chromosome aberrations in human cell cultures. The cytogenetic effect of asbest was inhibited by superoxide dismutase (50 mg/ml). The damaging effect of zeolite was decreased by the pharmacological drug bemithyl (0.007-0.07 mM) and completely eliminated by catalase (20 mg/ml). The results obtained indicate that mutagenic effect of dust particles of asbest and zeolite is mediated by oxygen radicals.

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.

Optimized Production of Coal Fly Ash Derived Synthetic Zeolites for Mercury Removal from Wastewater

NASA Astrophysics Data System (ADS)

Tauanov, Z.; Shah, D.; Itskos, G.; Inglezakis, V.

2017-09-01

Coal fly ash (CFA) derived synthetic zeolites have become popular with recent advances and its ever-expanding range of applications, particularly as an adsorbent for water and gas purification and as a binder or additive in the construction industry and agriculture. Among these applications, perpetual interest has been in utilization of CFA derived synthetic zeolites for removal of heavy metals from wastewater. We herein focus on utilization of locally available CFA for efficient adsorption of mercury from wastewater. To this end, experimental conditions were investigated so that to produce synthetic zeolites from Kazakhstani CFAs with conversion into zeolite up to 78%, which has remarkably high magnetite content. In particular, the effect of synthesis reaction temperature, reaction time, and loading of adsorbent were systematically investigated and optimized. All produced synthetic zeolites and the respective CFAs were characterized using XRD, XRF, PSA and porosimetric instruments to obtain microstructural and mineralogical data. Furthermore, the synthesized zeolites were studied for the removal of mercury from aqueous solutions. A comparison of removal eficiency and its relationship to the physical and chemical properties of the synthetic zeolites were analyzed and interpreted.

CIT-9: A Fault-Free Gmelinite Zeolite.

PubMed

Dusselier, Michiel; Kang, Jong Hun; Xie, Dan; Davis, Mark E

2017-10-16

A synthetic, fault-free gmelinite (GME) zeolite is prepared using a specific organic structure-directing agent (OSDA), cis-3,5-dimethylpiperidinium. The cis-isomers align in the main 12-membered ring (MR) channel of GME. Trans-isomer OSDA leads to the small-pore zeolite SSZ-39 with the OSDA in its cages. Data from N 2 -physisorption and rotation electron diffraction provide evidence for the openness of the 12 MR channel in the GME 12×8×8 pore architecture and the absence of stacking faults, respectively. CIT-9 is hydrothermally stable when K + -exchanged, while in the absence of exchange, the material transforms into an aluminous AFI-zeolite. The process of this phase-change was followed by in situ variable temperature powder X-ray diffraction. CIT-9 has the highest Si/Al ratio reported for GME, and along with its good porosity, opens the possibility of using GME in a variety of applications including catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of three patent foramen ovale closure devices in a randomized trial (Amplatzer versus CardioSEAL-STARflex versus Helex occluder).

PubMed

Taaffe, Margaret; Fischer, Evelyn; Baranowski, Andreas; Majunke, Nicolas; Heinisch, Corinna; Leetz, Michaela; Hein, Ralph; Bayard, Yves; Büscheck, Franziska; Reschke, Madlen; Hoffmann, Ilona; Wunderlich, Nina; Wilson, Neil; Sievert, Horst

2008-05-01

This randomized trial compared procedural complications and 30-day clinical outcomes of 3 patent foramen ovale (PFO) closure devices (Amplatzer, Helex, and CardioSEAL-STARflex). It examined 660 patients (361 men, 299 women, mean age 49.3+/-1.9 years), with 220 patients per group. All patients had a history of paradoxical embolism. All PFO closures were successful technically. Exchange of devices for others was most frequently required for the Helex occluder (7 of 220) and 2 of 220 in either of the other groups. Three device embolizations in the Helex group were retrieved and replaced successfully. One patient with a Helex occluder developed a transient ischemic attack and recovered without treatment. A hemopericardium in that group was punctured without affecting the device. One tamponade in the Amplatzer group required surgical device explantation. In 8 of 660 patients in the CardioSEAL-STARflex group, thrombi resolved after anticoagulation. Sixteen patients (11 in the CardioSEAL-STARflex group, 3 in the Amplatzer group, and 2 in the Helex group) had episodes of atrial fibrillation. PFOs were closed completely in 143 of 220 patients (65%) in the Amplatzer group, 116 of 220 patients (52.7%) in the Helex group, and 137 of 220 patients (62.3%) in the CardioSEAL-STARflex group at 30 days with significant differences between the Helex and Amplatzer occluders (p=0.0005) and the Helex and CardioSEAL-STARflex occluders (p=0.0003). PFO closure can be performed safely with each device. In conclusion, the Helex occluder embolized more frequently. Device thrombus formation and paroxysmal atrial fibrillation were more common with the CardioSEAL-STARflex occluder.

Biogas cleaning and upgrading with natural zeolites from tuffs.

PubMed

Paolini, Valerio; Petracchini, Francesco; Guerriero, Ettore; Bencini, Alessandro; Drigo, Serena

2016-01-01

CO2 adsorption on synthetic zeolites has become a consolidated approach for biogas upgrading to biomethane. As an alternative to synthetic zeolites, tuff waste from building industry was investigated in this study: indeed, this material is available at a low price and contains a high fraction of natural zeolites. A selective adsorption of CO2 and H2S towards CH4 was confirmed, allowing to obtain a high-purity biomethane (CO2 <2 g m(-3), i.e. 0.1%; H2S <1.5 mg m(-3)), suitable for injection in national grids or as vehicle fuel. The loading capacity was found to be 45 g kg(-1) and 40 mg kg(-1), for CO2 and H2S, respectively. Synthetic gas mixtures and real biogas samples were used, and no significant effects due to biogas impurities (e.g. humidity, dust, moisture, etc.) were observed. Thermal and vacuum regenerations were also optimized and confirmed to be possible, without significant variations in efficiency. Hence, natural zeolites from tuffs may successfully be used in a pressure/vacuum swing adsorption process.

Zeolite scaffolds for cultures of human breast cancer cells. Part II: Effect of pure and hybrid zeolite membranes on neoplastic and metastatic activity control.

PubMed

Tavolaro, Palmira; Martino, Guglielmo; Andò, Sebastiano; Tavolaro, Adalgisa

2016-11-01

This work is focused on the response of two invasive phenotypes of human breast cancer cells, MCF-7 and MDA-MB-231, grown on synthesized zeolite scaffolds in order to study the influence of those biomaterials in controlled conditions with and without anti-tumoral drug treatments. Our research was directed to the use of doxorubicin (DOX) and bergapten (5-MOP). The former is broadly considered the most active single agent available for the treatment of breast cancer, the second is a natural psoralen with an apoptotic effect. The results indicate that both drugs inhibit the cell viability of all cell lines grown on all zeolite scaffolds and that all Pure Zeolite Membranes are more responsive with respect to all Mixed Matrix Membranes. Moreover, the results after treatment with DOX at a concentration of 7.4μM for 24h, show that the expression of the matrix metalloproteinases (MMP-2 and MMP-9) is greatly reduced in both cell lines, especially in those adherent on Pure Zeolite Scaffolds. Copyright © 2016 Elsevier B.V. All rights reserved.

Study of Molecular-Shape Selectivity of Zeolites by Gas Chromatography

ERIC Educational Resources Information Center

Chao, Pei-Yu; Chuang, Yao-Yuan; Ho, Grace Hsiuying; Chuang, Shiow-Huey; Tsai, Tseng-Chang; Lee, Chi-Young; Tsai, Shang-Tien; Huang, Jun-Fu

2008-01-01

A sorption experiment using a gas chromatograph is described that can help students understand the "molecular-shape selectivity" behavior of zeolites in the subnano regime. Hexane isomers are used as probe molecules to demonstrate the sorption phenomena. In the experiment, a zeolite adsorbs certain hexane isomers with molecular sizes smaller than…

Phosphorus promotion and poisoning in zeolite-based materials: synthesis, characterisation and catalysis

PubMed Central

van der Bij, Hendrik E.

2015-01-01

Phosphorus and microporous aluminosilicates, better known as zeolites, have a unique but poorly understood relationship. For example, phosphatation of the industrially important zeolite H-ZSM-5 is a well-known, relatively inexpensive and seemingly straightforward post-synthetic modification applied by the chemical industry not only to alter its hydrothermal stability and acidity, but also to increase its selectivity towards light olefins in hydrocarbon catalysis. On the other hand, phosphorus poisoning of zeolite-based catalysts, which are used for removing nitrogen oxides from exhaust fuels, poses a problem for their use in diesel engine catalysts. Despite the wide impact of phosphorus–zeolite chemistry, the exact physicochemical processes that take place require a more profound understanding. This review article provides the reader with a comprehensive and state-of-the-art overview of the academic literature, from the first reports in the late 1970s until the most recent studies. In the first part an in-depth analysis is undertaken, which will reveal universal physicochemical and structural effects of phosphorus–zeolite chemistry on the framework structure, accessibility, and strength of acid sites. The second part discusses the hydrothermal stability of zeolites and clarifies the promotional role that phosphorus plays. The third part of the review paper links the structural and physicochemical effects of phosphorus on zeolite materials with their catalytic performance in a variety of catalytic processes, including alkylation of aromatics, catalytic cracking, methanol-to-hydrocarbon processing, dehydration of bioalcohol, and ammonia selective catalytic reduction (SCR) of NOx. Based on these insights, we discuss potential applications and important directions for further research. PMID:26051875

Phosphorus promotion and poisoning in zeolite-based materials: synthesis, characterisation and catalysis.

PubMed

van der Bij, Hendrik E; Weckhuysen, Bert M

2015-10-21

Phosphorus and microporous aluminosilicates, better known as zeolites, have a unique but poorly understood relationship. For example, phosphatation of the industrially important zeolite H-ZSM-5 is a well-known, relatively inexpensive and seemingly straightforward post-synthetic modification applied by the chemical industry not only to alter its hydrothermal stability and acidity, but also to increase its selectivity towards light olefins in hydrocarbon catalysis. On the other hand, phosphorus poisoning of zeolite-based catalysts, which are used for removing nitrogen oxides from exhaust fuels, poses a problem for their use in diesel engine catalysts. Despite the wide impact of phosphorus-zeolite chemistry, the exact physicochemical processes that take place require a more profound understanding. This review article provides the reader with a comprehensive and state-of-the-art overview of the academic literature, from the first reports in the late 1970s until the most recent studies. In the first part an in-depth analysis is undertaken, which will reveal universal physicochemical and structural effects of phosphorus-zeolite chemistry on the framework structure, accessibility, and strength of acid sites. The second part discusses the hydrothermal stability of zeolites and clarifies the promotional role that phosphorus plays. The third part of the review paper links the structural and physicochemical effects of phosphorus on zeolite materials with their catalytic performance in a variety of catalytic processes, including alkylation of aromatics, catalytic cracking, methanol-to-hydrocarbon processing, dehydration of bioalcohol, and ammonia selective catalytic reduction (SCR) of NOx. Based on these insights, we discuss potential applications and important directions for further research.

Atomistic simulations of CO2 and N2 within cage-type silica zeolites.

PubMed

Madison, Lindsey; Heitzer, Henry; Russell, Colin; Kohen, Daniela

2011-03-01

The behavior of CO(2) and N(2), both as single components and as binary mixtures, in two cage-type silica zeolites was studied using atomistic simulations. The zeolites considered, ITQ-3 and paradigm cage-type zeolite ZK4 (the all-silica analog of LTA), were chosen so that the principles illustrated can be generalized to other adsorbent/adsorbate systems with similar topology and types of interactions. N(2) was chosen both because of the potential uses of N(2)/CO(2) separations and because it differs from CO(2) most significantly in the magnitude of its Coulombic interactions with zeolites. Despite similarities between N(2) and CO(2) diffusion in other materials, we show here that the diffusion of CO(2) within cage-type zeolites is dominated by an energy barrier to diffusion located at the entrance to the narrow channels connecting larger cages. This barrier originates in Coulombic interactions between zeolites and CO(2)'s quadrupole and results in well-defined orientations for the diffusing molecules. Furthermore, CO(2)'s favorable electrostatic interactions with the zeolite framework result in preferential binding in the windows between cages. N(2)'s behavior, in contrast, is more consistent with that of molecules previously studied. Our analysis suggests that CO(2)'s behavior might be common for adsorbates with quadrupoles that interact strongly with a material that has narrow windows between cages.

Effect of zinc oxide amounts on the properties and antibacterial activities of zeolite/zinc oxide nanocomposite.

PubMed

Alswat, Abdullah A; Ahmad, Mansor Bin; Saleh, Tawfik A; Hussein, Mohd Zobir Bin; Ibrahim, Nor Azowa

2016-11-01

Nanocomposites of zinc oxide loaded on a zeolite (Zeolite/ZnO NCs) were prepared using co-precipitation method. The ratio effect of ZnO wt.% to the Zeolite on the antibacterial activities was investigated. Various techniques were used for the nanocomposite characterization, including UV-vis, FTIR, XRD, EDX, FESEM and TEM. XRD patterns showed that ZnO peak intensity increased while the intensities of Zeolite peaks decreased. TEM images indicated a good distribution of ZnO-NPs onto the Zeolite framework and the cubic structure of the zeolite was maintained. The average particle size of ZnO-nanoparticles loaded on the surface of the Zeolite was in the range of 1-10nm. Moreover, Zeolite/ZnO NCs showed noticeable antibacterial activities against the tested bacteria; Gram- positive and Gram- negative bacteria, under normal light. The efficiency of the antibacterial increased with increasing the wt.% from 3 to 8 of ZnO NPs, and it reached 87% against Escherichia coli E266. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasonic assisted synthesis of Bikitaite zeolite: A potential material for hydrogen storage application.

PubMed

Roy, Priyanka; Das, Nandini

2017-05-01

Li containing Bikitaite zeolite has been synthesized by an ultrasound-assisted method and used as a potential material for hydrogen storage application. The Sonication energy was varied from 150W to 250W and irradiation time from 3h to 6h. The Bikitaite nanoparticles were characterized by X-ray diffraction (XRD), infrared (IR) spectral analysis, and field-emission scanning electron microscopy (FESEM) thermo-gravimetrical analysis and differential thermal analysis (TGA, DTA). XRD and IR results showed that phase pure, nano crystalline Bikitaite zeolites were started forming after 3h irradiation and 72h of aging with a sonication energy of 150W and nano crystalline Bikitaite zeolite with prominent peaks were obtained after 6h irradiation of 250W sonic energy. The Brunauer-Emmett-Teller (BET) surface area of the powder by N 2 adsorption-desorption measurements was found to be 209m 2 /g. The TEM micrograph and elemental analysis showed that desired atomic ratio of the zeolite was obtained after 6h irradiation. For comparison, sonochemical method, followed by the hydrothermal method, with same initial sol composition was studied. The effect of ultrasonic energy and irradiation time showed that with increasing sonication energy, and sonication time phase formation was almost completed. The FESEM images revealed that 50nm zeolite crystals were formed at room temperature. However, agglomerated particles having woollen ball like structure was obtained by sonochemical method followed by hydrothermal treatment at 100°C for 24h. The hydrogen adsorption capacity of Bikitaite zeolite with different Li content, has been investigated. Experimental results indicated that the hydrogen adsorption capacities were dominantly related to their surface areas as well as total pore volume of the zeolite. The hydrogen adsorption capacity of 143.2c.c/g was obtained at 77K and ambient pressure of (0.11MPa) for the Bikitaite zeolite with 100% Li, which was higher than the reported values for

Magnetic targeting to enhance microbubble delivery in an occluded microarterial bifurcation

NASA Astrophysics Data System (ADS)

de Saint Victor, M.; Carugo, D.; Barnsley, L. C.; Owen, J.; Coussios, C.-C.; Stride, E.

2017-09-01

Ultrasound and microbubbles have been shown to accelerate the breakdown of blood clots both in vitro and in vivo. Clinical translation of this technology is still limited, however, in part by inefficient microbubble delivery to the thrombus. This study examines the obstacles to delivery posed by fluid dynamic conditions in occluded vasculature and investigates whether magnetic targeting can improve microbubble delivery. A 2D computational fluid dynamic model of a fully occluded Y-shaped microarterial bifurcation was developed to determine: (i) the fluid dynamic field in the vessel with inlet velocities from 1-100 mm s-1 (corresponding to Reynolds numbers 0.25-25) (ii) the transport dynamics of fibrinolytic drugs; and (iii) the flow behavior of microbubbles with diameters in the clinically-relevant range (0.6-5 µm). In vitro experiments were carried out in a custom-built microfluidic device. The flow field was characterized using tracer particles, and fibrinolytic drug transport was assessed using fluorescence microscopy. Lipid-shelled magnetic microbubbles were fluorescently labelled to determine their spatial distribution within the microvascular model. In both the simulations and experiments, the formation of laminar vortices and an abrupt reduction of fluid velocity were observed in the occluded branch of the bifurcation, severely limiting drug transport towards the occlusion. In the absence of a magnetic field, no microbubbles reached the occlusion, remaining trapped in the first vortex, within 350 µm from the bifurcation center. The number of microbubbles trapped within the vortex decreased as the inlet velocity increased, but was independent of microbubble size. Application of a magnetic field (magnetic flux density of 76 mT, magnetic flux density gradient of 10.90 T m-1 at the centre of the bifurcation) enabled delivery of microbubbles to the occlusion and the number of microbubbles delivered increased with bubble size and with decreasing inlet velocity.

A study on removing nitrogen from paddy field rainfall runoff by an ecological ditch-zeolite barrier system.

PubMed

Wang, Xiaoling; Li, Jiansheng; Li, Songmin; Zheng, Xiaotong

2017-12-01

Ecological ditches and zeolite have been widely applied in the removal of farmland nonpoint source pollution separately; little research has been done on the effects of combining the two methods. Specifically, few studies have focused on the in situ regeneration of zeolite. A 2-year field experiment using an ecological ditch-zeolite barrier system was conducted in a paddy field of summer rice-winter wheat rotation in the Taihu Lake area. The system consisted of two zeolite barriers positioned at one third and two thirds of the length of the ditch. This study focused on the effect of the system on in situ nitrogen removal during the rice-growing season. Simultaneous laboratory kinetics experiments with natural zeolite and a series of adsorbed zeolites taken from the ditch at different time were also conducted. The concentration removal efficiencies of total nitrogen are averaged 24.66% in 2014 and 30.39% in 2015. Meanwhile, the cumulative adsorption quantity of ammonia nitrogen by the two barriers accounted for 49.27% of the ammonia nitrogen removed in 2014 and 54.35% of that in 2015. The amount of nitrogen adsorbed by plants was larger than that adsorbed by zeolite. The breakthrough curves of the zeolite and the characteristics of the zeolite surface structures from different periods all demonstrated that the zeolite can be regenerated in situ in the case of unsaturated zeolite within the ecological ditch. It can be concluded that an ecological ditch-zeolite barrier system is a realistic option for removing nitrogen from agricultural rainfall runoff in the Taihu Lake area.

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

PubMed Central

Liu, Zhendong; Okabe, Kotatsu; Anand, Chokkalingam; Yonezawa, Yasuo; Zhu, Jie; Yamada, Hiroki; Endo, Akira; Yanaba, Yutaka; Yoshikawa, Takeshi; Ohara, Koji; Okubo, Tatsuya; Wakihara, Toru

2016-01-01

The hydrothermal synthesis of zeolites carried out in batch reactors takes a time so long (typically, on the order of days) that the crystallization of zeolites has long been believed to be very slow in nature. We herein present a synthetic process for ZSM-5, an industrially important zeolite, on the order of seconds in a continuous flow reactor using pressurized hot water as a heating medium. Direct mixing of a well-tuned precursor (90 °C) with the pressurized water preheated to extremely high temperature (370 °C) in the millimeter-sized continuous flow reactor resulted in immediate heating to high temperatures (240–300 °C); consequently, the crystallization of ZSM-5 in a seed-free system proceeded to completion within tens of or even several seconds. These results indicate that the crystallization of zeolites can complete in a period on the order of seconds. The subtle design combining a continuous flow reactor with pressurized hot water can greatly facilitate the mass production of zeolites in the future. PMID:27911823

Synthetic zeolites and other microporous oxide molecular sieves

PubMed Central

Sherman, John D.

1999-01-01

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. PMID:10097059

The removal of bacteria by modified natural zeolites.

PubMed

Milán, Z; de Las Pozas, C; Cruz, M; Borja, R; Sánchez, E; Ilangovan, K; Espinosa, Y; Luna, B

2001-01-01

The removal effect of natural and modified zeolites containing different heavy metals (Ni2+, Zn2+, Fe3+ and Cu2+) on pure cultures of Escherichia coli and Staphylococcus aureus in a solid medium was evaluated in this work. These experiments were carried out in a continuous mode treating municipal wastewater. Faecal coliform species and Pseudomonas aeruginosa were identified. The rate constants of heavy metal lixiviation were determined using a first order kinetic model. The removal effect of modified natural zeolites in both a solid medium and in continuous mode showed an increased elimination of the bacterial population. The results established a decreasing order of the removal effect as follows: Cu2+ > Fe3+ > Zn2+ > Ni2+. The best performance of columns was obtained for inlet bacterial concentrations below 10(6) cells/100 ml. Most of the identified bacterial species were affected by copper modified zeolites, although Serratia marcescens presented the highest sensitivity and Klebsiella pneumoniae the greatest resistance.

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.

Adsorption and separation of n/iso-pentane on zeolites: A GCMC study.

PubMed

Fu, Hui; Qin, Hansong; Wang, Yajun; Liu, Yibin; Yang, Chaohe; Shan, Honghong

2018-03-01

Separation of branched chain hydrocarbons and straight chain hydrocarbons is very important in the isomerization process. Grand canonical ensemble Monte Carlo simulations were used to investigate the adsorption and separation of iso-pentane and n-pentane in four types of zeolites: MWW, BOG, MFI, and LTA. The computation of the pure components indicates that the adsorption capacity is affected by physical properties of zeolite, like pore size and structures, and isosteric heat. In BOG, MFI and LTA, the amount of adsorption of n-pentane is higher than iso-pentane, while the phenomenon is contrary in MWW. For a given zeolite, a stronger adsorption heat corresponds to a higher loading. In the binary mixture simulations, the separation capacity of n-and iso-pentane increases with the elevated pressure and the increasing iso-pentane composition. The adsorption mechanism and competition process have been examined. Preferential adsorption contributions prevail at low pressure, however, the size effect becomes important with the increasing pressure, and the relatively smaller n-pentane gradually competes successfully in binary adsorption. Among these zeolites, MFI has the best separation performance due to its high shape selectivity. This work helps to better understand the adsorption and separation performance of n- and iso-pentane in different zeolites and explain the relationship between zeolite structures and adsorption performance. Copyright © 2017 Elsevier Inc. All rights reserved.

Ethylene formation by dehydration of ethanol over medium pore zeolites

NASA Astrophysics Data System (ADS)

Gołąbek, Kinga; Tarach, Karolina A.; Filek, Urszula; Góra-Marek, Kinga

2018-03-01

In this work, the role of pore arrangement of 10-ring zeolites ZSM-5, TNU-9 and IM-5 on their catalytic properties in ethanol transformation were investigated. Among all the studied catalysts, the zeolite IM-5, characterized by limited 3-dimensionality, presented the highest conversion of ethanol and the highest yields of diethyl ether (DEE) and ethylene. The least active and selective to ethylene and C3 + products was zeolite TNU-9 with the largest cavities formed on the intersection of 10-ring channels. The catalysts varied, however, in lifetime, and their deactivation followed the order: IM-5 > TNU-9 > ZSM-5. The processes taking place in the microporous zeolite environment were tracked by IR spectroscopy and analysed by the 2D correlation analysis (2D COS) allowing for an insight into the nature of chemisorbed adducts and transition products of the reaction. The cage dimension was found as a decisive factor influencing the tendency for coke deposition, herein identified as polymethylated benzenes, mainly 1,2,4-trimethyl-benzene.

Ethylene formation by dehydration of ethanol over medium pore zeolites.

PubMed

Gołąbek, Kinga; Tarach, Karolina A; Filek, Urszula; Góra-Marek, Kinga

2018-03-05

In this work, the role of pore arrangement of 10-ring zeolites ZSM-5, TNU-9 and IM-5 on their catalytic properties in ethanol transformation were investigated. Among all the studied catalysts, the zeolite IM-5, characterized by limited 3-dimensionality, presented the highest conversion of ethanol and the highest yields of diethyl ether (DEE) and ethylene. The least active and selective to ethylene and C 3+ products was zeolite TNU-9 with the largest cavities formed on the intersection of 10-ring channels. The catalysts varied, however, in lifetime, and their deactivation followed the order: IM-5>TNU-9>ZSM-5. The processes taking place in the microporous zeolite environment were tracked by IR spectroscopy and analysed by the 2D correlation analysis (2D COS) allowing for an insight into the nature of chemisorbed adducts and transition products of the reaction. The cage dimension was found as a decisive factor influencing the tendency for coke deposition, herein identified as polymethylated benzenes, mainly 1,2,4-trimethyl-benzene. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermal transpiration in zeolites: A mechanism for motionless gas pumps

NASA Astrophysics Data System (ADS)

Gupta, Naveen K.; Gianchandani, Yogesh B.

2008-11-01

We explore the use of a naturally occurring zeolite, clinoptilolite, for a chip-scale, thermal transpiration-based gas pump. The nanopores in clinoptilolite enable the required free-molecular flow, even at atmospheric pressure. The pump utilizes a foil heater located between zeolite disks in a plastic package. A 2.3mm thick zeolite disk generates a typical gas flow rate of 6.6×10-3 cc/min-cm2 with an input power of <300mW/cm2. The performance is constrained by imperfections in clinoptilolite, which provide estimated leakage apertures of 10.2-13.5μm/cm2 of flow cross section. The transient response of the pump is studied to quantify nonidealities.

Balloon-Occluded Percutaneous Transhepatic Obliteration of Isolated Vesical Varices Causing Gross Hematuria

PubMed Central

Lim, Dong Hoon; Kim, Min Seok; Kim, Chul Sung

2013-01-01

Gross hematuria secondary to vesical varices is an unusual presentation. We report such a case recurrent gross hematuria in a male patient who had a history of bladder substitution with ileal segments that had been treated by balloon-occluded percutaneous transhepatic obliteration of vesical varices. PMID:23323037

Anammox-zeolite system acting as buffer to achieve stable effluent nitrogen values.

PubMed

Yapsakli, Kozet; Aktan, Cigdem Kalkan; Mertoglu, Bulent

2017-02-01

For a successful nitrogen removal, Anammox process needs to be established in line with a stable partial nitritation pretreatment unit since wastewater influent is mostly unsuitable for direct treatment by Anammox. Partial nitritation is, however, a critical bottleneck for the nitrogen removal since it is often difficult to maintain the right proportions of NO 2 -N and NH 4 -N during long periods of time for Anammox process. This study investigated the potential of Anammox-zeolite biofilter to buffer inequalities in nitrite and ammonium nitrogen in the influent feed. Anammox-zeolite biofilter combines the ion-exchange property of zeolite with the biological removal by Anammox process. Continuous-flow biofilter was operated for 570 days to test the response of Anammox-zeolite system for irregular ammonium and nitrite nitrogen entries. The reactor demonstrated stable and high nitrogen removal efficiencies (approximately 95 %) even when the influent NO 2 -N to NH 4 -N ratios were far from the stoichiometric ratio for Anammox reaction (i.e. NO 2 -N to NH 4 -N ranging from 0 to infinity). This is achieved by the sorption of surplus NH 4 -N by zeolite particles in case ammonium rich influent came in excess with respect to Anammox stoichiometry. Similarly, when ammonium-poor influent is fed to the reactor, ammonium desorption took place due to shifts in ion-exchange equilibrium and deficient amount were supplied by previously sorbed NH 4 -N. Here, zeolite acted as a preserving reservoir of ammonium where both sorption and desorption took place when needed and this caused the Anammox-zeolite system to act as a buffer system to generate a stable effluent.

Planar Zeolite Film-Based Potentiometric Gas Sensors Manufactured by a Combined Thick-Film and Electroplating Technique

PubMed Central

Marr, Isabella; Reiß, Sebastian; Hagen, Gunter; Moos, Ralf

2011-01-01

Zeolites are promising materials in the field of gas sensors. In this technology-oriented paper, a planar setup for potentiometric hydrocarbon and hydrogen gas sensors using zeolites as ionic sodium conductors is presented, in which the Pt-loaded Na-ZSM-5 zeolite is applied using a thick-film technique between two interdigitated gold electrodes and one of them is selectively covered for the first time by an electroplated chromium oxide film. The influence of the sensor temperature, the type of hydrocarbons, the zeolite film thickness, and the chromium oxide film thickness is investigated. The influence of the zeolite on the sensor response is briefly discussed in the light of studies dealing with zeolites as selectivity-enhancing cover layers. PMID:22164042

An Introduction to Zeolite Synthesis Using Imidazolium-Based Cations as Organic Structure-Directing Agents.

PubMed

Vinaches, Paloma; Bernardo-Gusmão, Katia; Pergher, Sibele B C

2017-08-06

Zeolite synthesis is a wide area of study with increasing popularity. Several general reviews have already been published, but they did not summarize the study of imidazolium species in zeolite synthesis. Imidazolium derivatives are promising compounds in the search for new zeolites and can be used to help understand the structure-directing role. Nearly 50 different imidazolium cations have already been used, resulting in a variety of zeolitic types, but there are still many derivatives to be studied. In this context, the purpose of this short review is to help researchers starting in this area by summarizing the most important concepts related to imidazolium-based zeolite studies and by presenting a table of recent imidazolium derivatives that have been recently studied to facilitate filling in the knowledge gaps.

Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen

DOEpatents

Frei, Heinz; Blatter, Fritz; Sun, Hai

1999-01-01

A process 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.

Inoculum and zeolite synergistic effect on anaerobic digestion of poultry manure.

PubMed

Fotidis, Ioannis A; Kougias, Panagiotis G; Zaganas, Ioannis D; Kotsopoulos, Thomas A; Martzopoulos, Gerasimos G

2014-01-01

Poultry manure is an ammonia-rich substrate due to its high content of proteins and amino acids. Ammonia is the major inhibitor of anaerobic digestion (AD) process, affecting biogas production and causing great economic losses to the biogas plants. In this study, the effect of different natural zeolite dosages on the mesophilic AD of poultry manure inoculated with a non-acclimatized to ammonia inoculum (dairy manure) was investigated. Additionally, a comparative analysis was performed between the data extracted from this study and the results of a previous study, which has been conducted under the same experimental conditions but with the use of ammonia acclimatized inoculum (swine manure). At 5 and 10 g zeolite L(-1), the methane yield of poultry manure was 43.4% and 80.3% higher compared with the experimental set without zeolite addition. However, the ammonia non-acclimatized inoculum was not efficient in digesting poultry manure even in the presence of 10 g zeolite L(-1), due to low methane production (only 39%) compared with the maximum theoretical yield. Finally, ammonia acclimatized inoculum and zeolite have demonstrated a possible 'synergistic effect', which led to a more efficient AD of poultry manure. The results of this study could potentially been used by the biogas plant operators to efficiently digest poultry manure.

Sn-Beta zeolites with borate salts catalyse the epimerization of carbohydrates via an intramolecular carbon shift

PubMed Central

Gunther, William R.; Wang, Yuran; Ji, Yuewei; Michaelis, Vladimir K.; Hunt, Sean T.; Griffin, Robert G.; Román-Leshkov, Yuriy

2012-01-01

Carbohydrate epimerization is an essential technology for the widespread production of rare sugars. In contrast to other enzymes, most epimerases are only active on sugars substituted with phosphate or nucleotide groups, thus drastically restricting their use. Here we show that Sn-Beta zeolite in the presence of sodium tetraborate catalyses the selective epimerization of aldoses in aqueous media. Specifically, a 5 wt% aldose (for example, glucose, xylose or arabinose) solution with a 4:1 aldose:sodium tetraborate molar ratio reacted with catalytic amounts of Sn-Beta yields near-equilibrium epimerization product distributions. The reaction proceeds by way of a 1,2 carbon shift wherein the bond between C-2 and C-3 is cleaved and a new bond between C-1 and C-3 is formed, with C-1 moving to the C-2 position with an inverted configuration. This work provides a general method of performing carbohydrate epimerizations that surmounts the main disadvantages of current enzymatic and inorganic processes. PMID:23047667

Evaluation of the adsorptive behavior of cesium and strontium on hydroxyapatite and zeolite for decontamination of radioactive substances.

PubMed

Ozeki, K; Aoki, H

2016-08-12

Removal of radioactive substances, such as cesium (Cs) and strontium (Sr), has become an emerging issue after the Fukushima Daiichi Nuclear Power Plant Disaster. To assess the possibility that hydroxyapatite (HA) and zeolites can be used for removal of radioactive substances, the adsorption capacities of Cs and Sr on the HA and a zeolite were investigated. The influence of Fe ions on Cs and Sr adsorption on the HA and the zeolite was also evaluated, because Fe ions are the most effective inhibitor of Cs adsorption on the zeolite.In the Cs adsorption process on the HA and the zeolite, the zeolite showed a higher adsorption ratio than the HA, and the maximum sorption capacity of the zeolite was calculated as 196 mg/g, whereas the HA showed a higher Sr adsorption ratio than the zeolite. The maximum sorption capacity of Sr on the HA was 123 mg/g. Under coexistence with Fe, Cs adsorption on the zeolite decreased with increasing Fe concentration, reaching 2.0 ± 0.8% at 0.1 M Fe concentration. In contrast, Cs adsorption on the zeolite was improved by adding the HA. In the case of coexistence of the HA, the Cs adsorption on the mixture of the HA and the zeolite was 52.4% ± 3.6 % at 0.1 M Fe concentration, although Cs adsorption on the HA alone was quite low. In the Fe adsorption processes of the HA and the zeolite, the HA exhibited a maximum sorption capacity of 256 mg/g, which was much higher than that of the zeolite (111 mg/g). The high affinity of Fe on the HA contributes to the improvement of the deteriorated Cs adsorption on the zeolite due to Fe ions.

Effect of Fe3O4 addition on removal of ammonium by zeolite NaA.

PubMed

Liu, Haibo; Peng, Shuchuan; Shu, Lin; Chen, Tianhu; Bao, Teng; Frost, Ray L

2013-01-15

Magnetic zeolite NaA with different Fe(3)O(4) loadings was prepared by hydrothermal synthesis based on metakaolin and Fe(3)O(4). The effect of added Fe(3)O(4) on the removal of ammonium by zeolite NaA was investigated by varying the Fe(3)O(4) loading, pH, adsorption temperature, initial concentration, adsorption time. Langmuir, Freundlich, and pseudo-second-order modeling were used to describe the nature and mechanism of ammonium ion exchange using both zeolite and magnetic zeolite. Thermodynamic parameters such as change in Gibbs free energy, enthalpy and entropy were calculated. The results show that all the selected factors affect the ammonium ion exchange by zeolite and magnetic zeolite, however, the added Fe(3)O(4) apparently does not affect the ion exchange performance of zeolite to the ammonium ion. Freundlich model provides a better description of the adsorption process than Langmuir model. Moreover, kinetic analysis indicates the exchange of ammonium on the two materials follows a pseudo-second-order model. Thermodynamic analysis makes it clear that the adsorption process of ammonium is spontaneous and exothermic. Regardless of kinetic or thermodynamic analysis, all the results suggest that no considerable effect on the adsorption of the ammonium ion by zeolite is found after the addition of Fe(3)O(4). According to the results, magnetic zeolite NaA can be used for the removal of ammonium due to the good adsorption performance and easy separation method from aqueous solution. Copyright © 2012 Elsevier Inc. All rights reserved.

Development of electrochemical biosensors with various types of zeolites

NASA Astrophysics Data System (ADS)

Soldatkina, O. V.; Kucherenko, I. S.; Soldatkin, O. O.; Pyeshkova, V. M.; Dudchenko, O. Y.; Akata Kurç, B.; Dzyadevych, S. V.

2018-03-01

In the work, different types of zeolites were used for the development of enzyme-based electrochemical biosensors. Zeolites were added to the biorecognition elements of the biosensors and served as additional components of the biomembranes or adsorbents for enzymes. Three types of biosensors (conductometric, amperometric and potentiometric) were studied. The developed biosensors were compared with the similar biosensors without zeolites. The biosensors contained the following enzymes: urease, glucose oxidase, glutamate oxidase, and acetylcholinesterase and were intended for the detection of urea, glucose, glutamate, and acetylcholine, respectively. Construction of the biosensors using the adsorption of enzymes on zeolites has several advantages: simplicity, good reproducibility, quickness, absence of toxic compounds. These benefits are particularly important for the standardization and further mass production of the biosensors. Furthermore, a biosensor for the sucrose determination contained a three-enzyme system (invertase/mutatorase/glucose oxidase), immobilized by a combination of adsorption on silicalite and cross-linking via glutaraldehyde; such combined immobilization demonstrated better results as compared with adsorption or cross-linking separately. The analysis of urea and sucrose concentrations in the real samples was carried out. The results, obtained with biosensors, had high correlation with the results of traditional analytical methods, thus the developed biosensors are promising for practical applications.

Towards Organic Zeolites and Inclusion Catalysts: Heptazine Imide Salts Can Exchange Metal Cations in the Solid State.

PubMed

Savateev, Aleksandr; Pronkin, Sergey; Willinger, Marc Georg; Antonietti, Markus; Dontsova, Dariya

2017-07-04

Highly crystalline potassium (heptazine imides) were prepared by the thermal condensation of substituted 1,2,4-triazoles in eutectic salt melts. These semiconducting salts are already known to be highly active photocatalysts, for example, for the visible-light-driven generation of hydrogen from water. Herein, we show that within the solid-state structure, potassium ions can be exchanged to other metal ions while the crystal habitus is essentially preserved. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selective Ring Opening of 1-Methylnaphthalene Over NiW-Supported Catalyst Using Dealuminated Beta Zeolite.

PubMed

Kim, Eun-Sang; Lee, You-Jin; Kim, Jeong-Rang; Kim, Joo-Wan; Kim, Tae-Wan; Chae, Ho-Jeong; Kim, Chul-Ung; Lee, Chang-Ha; Jeong, Soon-Yong

2016-02-01

Nanoporous Beta zeolite was dealuminated by weak acid treatment for reducing the acidity. Bi-functional catalysts were prepared using commercial Beta zeolites and the dealuminated zeolites for acidic function, NiW for metallic function. 1-Methylnaphthalene was selected as a model compound for multi-ring aromatics in heavy oil, and its selective ring opening reaction has been investigated using the prepared bi-functional catalysts with different acidity in fixed bed reaction system. The dealuminated Beta zeolites, which crystal structure and nanoporosity were maintained, showed the higher SiO2/Al2O3 ratio and smaller acidity than their original zeolite. NiW-supported catalyst using the dealuminated Beta zeolite with SiO2/Al203 mole ratio of 55 showed the highest performance for the selective ring opening. The acidity of catalyst seemed to play an important role as active sites for the selective ring opening of 1-methylnaphthalene but there should be some optimum catalyst acidity for the reaction. The acidity of Beta zeolite could be controlled by the acid treatment and the catalyst with the optimum acidity for the selective ring opening could be prepared.

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

PubMed Central

2014-01-01

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. PMID:24636423

A Sensor Based on LiCl/NaA Zeolite Composites for Effective Humidity Sensing.

PubMed

Zhang, Ying; Xiang, Hongyu; Sun, Liang; Xie, Qiuhong; Liu, Man; Chen, Yu; Ruan, Shengping

2018-03-01

LiCl/NaA zeolite composites were successfully prepared by doping 1 wt%, 2 wt%, 5 wt%, and 8 wt% of LiCl into NaA zeolite. The humidity sensing properties of LiCl/NaA composites were investigated among 11% 95% relative humidity (RH). The LiCl/NaA composites exhibited better humidity sensing properties than pure NaA zeolite. The sensor made by 2 wt% Li-doped NaA zeolite possesses the best linearly in the whole RH. These results demonstrate that the LiCl/NaA composites have the potential application in humidity sensing.

Performance of Nitrogen and Phosphorus Removal in Petrochemical Wastewater by Zeolited Fly Ash

NASA Astrophysics Data System (ADS)

Li, Zheng; Gu, Guizhou; Ji, Shenghao

2018-05-01

The zeolitized fly ash was synthesized by alkali melt hydrothermal method. The cation exchange capacity of zeolitized fly ash was far greater than the raw material fly ash. The main component was NaP1 zeolite (Na6Al6Si10O32·12H2O), followed by mullite, and a small amount of heterozygous crystals. The effect of synthetic zeolite dosage, pH value, adsorption time and reaction temperature on the effect of nitrogen and phosphorus removal in petrochemical wastewater were investigated. The results showed that when the zeolitized fly ash dosage was 9 g/L, the petrochemical wastewater pH value was 6∼8, adsorption time was 30 min and the reaction temperature was 30°C, the synthetic zeolite had the best effect on the removal of TN and TP in petrochemical wastewater, and the removal was 65.5%, 91.4% respectively. Besides, the concentrations of TN and TP in the effluent were 11.04 mg/L, 0.31 mg/L respectively. The concentrations met the sewage discharge standard in petrochemical industry of "Liaoning sewage comprehensive discharge standard" (DB21 1627-2008). This study was to realize the comprehensive utilization of solid waste and achieve the purpose of waste and waste.

Corrosion Behavior of Yttria-Stabilized Zirconia-Coated 9Cr-1Mo Steel in Molten UCl3-LiCl-KCl Salt

NASA Astrophysics Data System (ADS)

Jagadeeswara Rao, Ch.; Venkatesh, P.; Prabhakara Reddy, B.; Ningshen, S.; Mallika, C.; Kamachi Mudali, U.

2017-02-01

For the electrorefining step in the pyrochemical reprocessing of spent metallic fuels of future sodium cooled fast breeder reactors, 9Cr-1Mo steel has been proposed as the container material. The electrorefining process is carried out using 5-6 wt.% UCl3 in LiCl-KCl molten salt as the electrolyte at 500 °C under argon atmosphere. In the present study, to protect the container vessel from hot corrosion by the molten salt, 8-9% yttria-stabilized zirconia (YSZ) ceramic coating was deposited on 9Cr-1Mo steel by atmospheric plasma spray process. The hot corrosion behavior of YSZ-coated 9Cr-1Mo steel specimen was investigated in molten UCl3-LiCl-KCl salt at 600 °C for 100-, 500-, 1000- and 2000-h duration. The results revealed that the weight change in the YSZ-coated specimen was insignificant even after exposure to molten salt for 2000 h, and delamination of coating did not occur. SEM examination showed the lamellar morphology of the YSZ coating after the corrosion test with occluded molten salt. The XRD analysis confirmed the presence of tetragonal and cubic phases of ZrO2, without any phase change. Formation of UO2 in some regions of the samples was evident from XRD results.

A new approach to evaluate natural zeolite ability to sorb lead (Pb) from aqueous solutions

NASA Astrophysics Data System (ADS)

Drosos, Evangelos I. P.; Karapanagioti, Hrissi K.

2013-04-01

Lead (Pb) is a hazardous pollutant commonly found in aquatic ecosystems. Among several methods available, the addition of sorbent amendments to soils or sediments is attractive, since its application is relatively simple, while it can also be cost effective when a low cost and re-usable sorbent is used; e.g. natural zeolites. Zeolites are crystalline aluminosilicates with a three-dimensional structure composed of a set of cavities occupied by large ions and water molecules. Zeolites can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+, which are rather loosely held and can readily be exchanged for others in an aqueous solution. Natural zeolites are capable of removing cations, such as lead, from aqueous solutions by ion exchange. There is a wide variation in the cation exchange capacity (CEC) of natural zeolites because of the different nature of various zeolites cage structures, natural structural defects, adsorbed ions, and their associated gangue minerals. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, such as clays and feldspars, metals, quartz, or other zeolites as well. These impurities affect the CEC even for samples originated from the same region but from a different source. CEC of the material increases with decreasing impurity content. Potentially exchangeable ions in such impurities do not necessarily participate in ion exchange mechanism, while, in some cases, impurities may additionally block the access to active sites. For zeoliferous rocks having the same percentage of a zeolitic phase, the CEC increases with decreasing Si/Al ratio, as the more Si ions are substituted by Al ions, the more negative the valence of the matrix becomes. Sodium seems to be the most effective exchangeable ion for lead. On the contrary, it is unlikely that the potassium content of the zeolite would be substituted. A pretreatment with high concentration solutions of Na, such as 2 M NaCl, can

Highly mesoporous single-crystalline zeolite beta synthesized using a nonsurfactant cationic polymer as a dual-function template.

PubMed

Zhu, Jie; Zhu, Yihan; Zhu, Liangkui; Rigutto, Marcello; van der Made, Alexander; Yang, Chengguang; Pan, Shuxiang; Wang, Liang; Zhu, Longfeng; Jin, Yinying; Sun, Qi; Wu, Qinming; Meng, Xiangju; Zhang, Daliang; Han, Yu; Li, Jixue; Chu, Yueying; Zheng, Anmin; Qiu, Shilun; Zheng, Xiaoming; Xiao, Feng-Shou

2014-02-12

Mesoporous zeolites are useful solid catalysts for conversion of bulky molecules because they offer fast mass transfer along with size and shape selectivity. We report here the successful synthesis of mesoporous aluminosilicate zeolite Beta from a commercial cationic polymer that acts as a dual-function template to generate zeolitic micropores and mesopores simultaneously. This is the first demonstration of a single nonsurfactant polymer acting as such a template. Using high-resolution electron microscopy and tomography, we discovered that the resulting material (Beta-MS) has abundant and highly interconnected mesopores. More importantly, we demonstrated using a three-dimensional electron diffraction technique that each Beta-MS particle is a single crystal, whereas most previously reported mesoporous zeolites are comprised of nanosized zeolitic grains with random orientations. The use of nonsurfactant templates is essential to gaining single-crystalline mesoporous zeolites. The single-crystalline nature endows Beta-MS with better hydrothermal stability compared with surfactant-derived mesoporous zeolite Beta. Beta-MS also exhibited remarkably higher catalytic activity than did conventional zeolite Beta in acid-catalyzed reactions involving large molecules.

Method for encapsulating nanoparticles in a zeolite matrix

DOEpatents

Coker, Eric N.

2007-12-11

A method for preparing a metal nanocluster composite material. A porous zeolitic material is treated with an aqueous metal compound solution to form a metal ion-exchanged zeolitic material, heated at a temperature ramp rate of less than 2.degree. C./min to an elevated temperature, cooled, contacted with an organic monomer and heating to induce polymerization, and heating the composite material to greater than 350.degree. C. under non-oxidizing conditions to form a metal nanocluster-carbon composite material with nanocluster sizes between approximately 0.6 nm and 10 nm.

Phonation Threshold Pressure Measurement With a Semi-Occluded Vocal Tract

PubMed Central

Titze, Ingo R.

2015-01-01

Purpose The purpose of this article was to determine if a semi-occluded vocal tract could be used to measure phonation threshold pressure. This is in contrast to the shutter technique, where an alternation between a fully occluded tract and an unoccluded tract is used. Method Five male and 5 female volunteers phonated through a thin straw held between the lips. Oral pressure behind the lips was measured. Mathematical predictions of phonation threshold pressures were compared to the measured ones over a range of frequencies. Results It was shown that, for a 2.5-mm diameter straw, phonation threshold pressures were obtainable over a 2-octave range of fundamental frequency by all volunteers. In magnitude, the pressures agreed with the 0.2–0.5 kPa values obtained in previous investigations. Sensitivity to viscoelastic and geometric properties of the vocal folds was generally not compromised with greater oral impedance, but some differences were predicted theoretically in contrast to an open mouth configuration. Conclusion Because phonation threshold pressure is always dependent on vocal tract interaction, it may be advantageous to choose an exact and fixed oral semi-occlusion for the measurement and interpret the results in light of the known acoustic load. PMID:19641082

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.

Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen

DOEpatents

Frei, Heinz; Blatter, Fritz; Sun, Hai

2001-01-01

A process for a combined selective thermal oxidation and photooxidation of hydrocarbons adsorbed onto zeolite matrices. A highly combined 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.

Electro-elastoviscous response of polyaniline functionalized nano-porous zeolite based colloidal dispersions.

PubMed

Chattopadhyay, Ankur; Rani, Poonam; Srivastava, Rajendra; Dhar, Purbarun

2018-06-01

The present article discusses the typical influence of grafted conducting polymers in the mesoscale pores of dielectric particles on the static and dynamic electrorheology and electro-viscoelastic behavior of corresponding colloids. Nanocrystalline meso-nanoporous zeolite has been prepared by chemical synthesis and subsequently polyaniline (PANI) coating has been implemented. Electrorheological (ER) suspensions have been formed by dispersing the nanoparticles in silicone oil and their viscoelastic behaviors are examined to understand the nature of such complex colloidal systems under electric fields. PANI-Zeolite ER fluids demonstrate higher static electroviscous effects and yield stress potential than untreated Zeolite, typically studied in literature. Transient electro-viscous characterizations show a stable and negligible hysteresis behavior when both the fluids are exposed to constant as well as time varying electric field intensities. Further oscillatory shear experiments of frequency and strain sweeps exhibit predominant elastic behavior in case of Zeolite based ER suspensions as compared to PANI systems. Detailed investigations reveal Zeolite based ER suspensions display enhanced relative yielding as well as electro-viscoelastic stability than the PANI-Zeolite. The steady state viscous behaviors are scaled against the non-dimensional Mason number to model the system behavior for both fluids. Experimental data of flow behaviors of both the ER fluids are compared with semi-classical models and it is found that the CCJ model possesses a closer proximity than traditional Bingham model, thereby revealing the fluids to be generic pseudo-linear fluids. The present article reveals that while the PANI based fluids are typically hailed superior in literature, it is only restricted to steady shear utilities. In case of dynamic and oscillatory systems, the traditional Zeolite based fluids exhibit superior ER caliber. Copyright © 2018 Elsevier Inc. All rights reserved.

Metalloenzyme-like catalyzed isomerizations of sugars by Lewis acid zeolites

PubMed Central

Bermejo-Deval, Ricardo; Assary, Rajeev S.; Nikolla, Eranda; Moliner, Manuel; Román-Leshkov, Yuriy; Hwang, Son-Jong; Palsdottir, Arna; Silverman, Dorothy; Lobo, Raul F.; Curtiss, Larry A.; Davis, Mark E.

2012-01-01

Isomerization of sugars is used in a variety of industrially relevant processes and in glycolysis. Here, we show that hydrophobic zeolite beta with framework tin or titanium Lewis acid centers isomerizes sugars, e.g., glucose, via reaction pathways that are analogous to those of metalloenzymes. Specifically, experimental and theoretical investigations reveal that glucose partitions into the zeolite in the pyranose form, ring opens to the acyclic form in the presence of the Lewis acid center, isomerizes into the acyclic form of fructose, and finally ring closes to yield the furanose product. The zeolite catalysts provide processing advantages over metalloenzymes such as an ability to work at higher temperatures and in acidic conditions that allow for the isomerization reaction to be coupled with other important conversions. PMID:22665778

Platinum/zeolite catalyst for reforming n-hexane: Kinetic and mechanistic considerations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lane, G.S.; Modica, F.S.; Miller, J.T.

A platinum/L-zeolite-reforming catalyst exhibits activity and selectivity for converting n-hexane into benzene than other Pt catalyst. The reaction pathways indicate that for all catalysts, e.g., Pt/K L or Pt/K Y, benzene is formed as a primary product by one-six-ring closure and methylcyclopentane is formed as a primary product via one-five-ring closure. The ratio for one-six to one-five-ring closure, however, is about two times greater for the Pt/K L than for the Pt/K Y, or other platinum catalysts. The preference for the one-six-ring closure in L zeolite appears to be related to the optimum pore size of the L zeolite. Inmore » addition to an increased selectivity for one-six-ring closure, the Pt/K L-zeolite catalyst also displays increased reactivity. For example, the turnover frequency of the Pt/K L-zeolite catalyst is 10 times higher for formation of benzene and 3.3 times higher for formation of methylcyclopentane compared with the Pt/K Y-zeolite catalyst. Although the Pt/K L is more reactive than Pt/K Y, the apparent activation energies, 54 kcal/mol for one-six-ring closure and 39 kcal/mol for one-five-ring closure, are the same for both catalysts. Differences in reactivity are associated with an increase in the preexponential term for the Pt/K L catalyst. The increased aromatics selectivity for Pt/K L is consistent with the confinement model which proposes that n-hexane is adsorbed as a six-ring pseudo-cycle resembling the transition state for one-six-ring closure.« less

Factors affecting adsorption characteristics of Zn2+ on two natural zeolites.

PubMed

Oren, Ali Hakan; Kaya, Abidin

2006-04-17

Mining-related and industrial wastes are primary sources of heavy metal contamination in soils and groundwater. The limitation of such waste in drinking water needs to meet government requirements in order to safeguard human health and environment. Zinc, one of the most preponderant pollutants, is difficult to remove from wastewater rather than other heavy metals (i.e. lead, copper and cadmium). This paper investigates Zn2+ adsorption characteristics of two natural zeolites found in the regions of Gordes and Bigadic, in western Turkey. The results show that the Zn2+ adsorption behavior of both zeolites is highly dependent on the pH. Adsorption dependence on lower pH values (pH<4) is explained by the dissolution of crystal structure and the competition of the zinc ions with the H+. Between pH 4 and 6, the basic mechanism is the ion exchange process. The results also showed that decrease in grain size does not increase the adsorption capacity of zeolite from Gordes, yet it increases that of zeolite from Bigadic about 23%. The results also reveal that an increase in the initial concentration of Zn2+ in the system causes an increase in the adsorption capacity to a degree, then it becomes more constant at higher concentrations. With this, the removal efficiency of Gordes zeolite is two times higher than that of Bigadic zeolite. Results show that an increase in slurry concentration results in a lower uptake of Zn2+. In the final part of the paper, we compared the experimental data with the Langmuir and Freundlich isotherms. The results show that there is a good fit between the experimental data and empirical isotherms.

Methylcellulose-Directed Synthesis of Nanocrystalline Zeolite NaA with High CO₂ Uptake.

PubMed

Shakarova, Dilshod; Ojuva, Arto; Bergström, Lennart; Akhtar, Farid

2014-07-28

Zeolite NaA nanocrystals with a narrow particle size distribution were prepared by template-free hydrothermal synthesis in thermo-reversible methylcellulose gels. The effects of the amount of methylcellulose, crystallization time and hydrothermal treatment temperature on the crystallinity and particle size distribution of the zeolite NaA nanocrystals were investigated. We found that the thermogelation of methylcellulose in the alkaline Na₂O-SiO₂-Al₂O₃-H₂O system played an important role in controlling the particle size. The synthesized zeolite nanocrystals are highly crystalline, as demonstrated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) shows that the nanocrystals can also display a well-defined facetted morphology. Gas adsorption studies on the synthesized nanocrystalline zeolite NaA showed that nanocrystals with a size of 100 nm displayed a high CO₂ uptake capacity (4.9 mmol/g at 293 K at 100 kPa) and a relatively rapid uptake rate compared to commercially available, micron-sized particles. Low-cost nanosized zeolite adsorbents with a high and rapid uptake are important for large scale gas separation processes, e.g., carbon capture from flue gas.

An Infectious Pseudoaneurysm Caused by Ventricular Septal Defect Occluder in Patent Ductus Arteriosus Closure in a Two-Year-Old Child.

PubMed

Li, Dingyang; Qiu, Qiu; Jin, Jing; Zhang, Changdong; Wang, Lijun; Zhang, Gangcheng

2017-12-12

We present a case of an infectious pseudoaneurysm after patent ductus arteriosus (PDA) closure with a ventricular septal defect (VSD) occluder in a two-year-old child. The aneurysm grew rapidly but was successfully removed in time and the patient survived. To our knowledge, this is the first report of an infectious pseudoaneurysm caused by VSD occluder in PDA closure.

Pioneering In Situ Recrystallization during Bead Milling: A Top-down Approach to Prepare Zeolite A Nanocrystals.

PubMed

Anand, Chokkalingam; Yamaguchi, Yudai; Liu, Zhendong; Ibe, Sayoko; Elangovan, Shanmugam P; Ishii, Toshihiro; Ishikawa, Tsuyoshi; Endo, Akira; Okubo, Tatsuya; Wakihara, Toru

2016-07-05

Top-down approach has been viewed as an efficient and straightforward method to prepare nanosized zeolites. Yet, the mechanical breaking of zeolite causes amorphization, which usually requires a post-milling recrystallization to obtain fully crystalline nanoparticles. Herein we present a facile methodology to prepare zeolite nanocrystals, where milling and recrystallization can be performed in situ. A milling apparatus specially designed to work under conditions of high alkalinity and temperature enables the in situ recrystallization during milling. Taking zeolite A as an example, we demonstrate its size reduction from ~3 μm to 66 nm in 30 min, which is quite faster than previous methods reported. Three functions, viz., miniaturization, amorphization and recrystallization were found to take effect concurrently during this one-pot process. The dynamic balance between these three functions was achieved by adjusting the milling period and temperature, which lead to the tuning of zeolite A particle size. Particle size and crystallinity of the zeolite A nanocrystals were confirmed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and water adsorption-desorption. This work presents a pioneering advancement in this field of nanosized zeolites, and will facilitate the mass production as well as boost the wide applications of nanosized zeolites.

Pioneering In Situ Recrystallization during Bead Milling: A Top-down Approach to Prepare Zeolite A Nanocrystals

PubMed Central

Anand, Chokkalingam; Yamaguchi, Yudai; Liu, Zhendong; Ibe, Sayoko; Elangovan, Shanmugam P.; Ishii, Toshihiro; Ishikawa, Tsuyoshi; Endo, Akira; Okubo, Tatsuya; Wakihara, Toru

2016-01-01

Top-down approach has been viewed as an efficient and straightforward method to prepare nanosized zeolites. Yet, the mechanical breaking of zeolite causes amorphization, which usually requires a post-milling recrystallization to obtain fully crystalline nanoparticles. Herein we present a facile methodology to prepare zeolite nanocrystals, where milling and recrystallization can be performed in situ. A milling apparatus specially designed to work under conditions of high alkalinity and temperature enables the in situ recrystallization during milling. Taking zeolite A as an example, we demonstrate its size reduction from ~3 μm to 66 nm in 30 min, which is quite faster than previous methods reported. Three functions, viz., miniaturization, amorphization and recrystallization were found to take effect concurrently during this one-pot process. The dynamic balance between these three functions was achieved by adjusting the milling period and temperature, which lead to the tuning of zeolite A particle size. Particle size and crystallinity of the zeolite A nanocrystals were confirmed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and water adsorption-desorption. This work presents a pioneering advancement in this field of nanosized zeolites, and will facilitate the mass production as well as boost the wide applications of nanosized zeolites. PMID:27378145

Hydrogen storage in Chabazite zeolite frameworks.

PubMed

Regli, Laura; Zecchina, Adriano; Vitillo, Jenny G; Cocina, Donato; Spoto, Giuseppe; Lamberti, Carlo; Lillerud, Karl P; Olsbye, Unni; Bordiga, Silvia

2005-09-07

We have recently highlighted that H-SSZ-13, a highly siliceous zeolite (Si/Al = 11.6) with a chabazitic framework, is the most efficient zeolitic material for hydrogen storage [A. Zecchina, S. Bordiga, J. G. Vitillo, G. Ricchiardi, C. Lamberti, G. Spoto, M. Bjørgen and K. P. Lillerud, J. Am. Chem. Soc., 2005, 127, 6361]. The aim of this new study is thus to clarify both the role played by the acidic strength and by the density of the polarizing centers hosted in the same framework topology in the increase of the adsorptive capabilities of the chabazitic materials towards H2. To achieve this goal, the volumetric experiments of H2 uptake (performed at 77 K) and the transmission IR experiment of H2 adsorption at 15 K have been performed on H-SSZ-13, H-SAPO-34 (the isostructural silico-aluminophosphate material with the same Brønsted site density) and H-CHA (the standard chabazite zeolite: Si/Al = 2.1) materials. We have found that a H2 uptake improvement has been obtained by increasing the acidic strength of the Brønsted sites (moving from H-SAPO-34 to H-SSZ-13). Conversely, the important increase of the Brønsted sites density (moving from H-SSZ-13 to H-CHA) has played a negative role. This unexpected behavior has been explained as follows. The additional Brønsted sites are in mutual interaction via H-bonds inside the small cages of the chabazitic framework and for most of them the energetic cost needed to displace the adjacent OH ligand is higher than the adsorption enthalpy of the OH...H2 adduct. From our work it can be concluded that proton exchanged chabazitic frameworks represent, among zeolites, the most efficient materials for hydrogen storage. We have shown that a proper balance between available space (volume accessible to hydrogen), high contact surface, and specific interaction with strong and isolated polarizing centers are the necessary characteristics requested to design better materials for molecular H2 storage.

Supported rhenium complexes: almost uniform rhenium tricarbonyls synthesized from CH3Re(CO)5 and HY zeolite.

PubMed

Lobo-Lapidus, Rodrigo J; Gates, Bruce C

2010-11-02

Supported rhenium complexes were prepared from CH(3)Re(CO)(5) and dealuminated HY zeolite or NaY zeolite, each with a Si/Al atomic ratio of 30. The samples were characterized with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. EXAFS data characterizing the sample formed by the reaction of CH(3)Re(CO)(5) with dealuminated HY zeolite show that the rhenium complexes were bonded to the zeolite frame, incorporating, on average, three carbonyl ligands per Re atom (as shown by Re-C and multiple-scattering Re-O EXAFS contributions). The IR spectra, consistent with this result, show that the supported rhenium carbonyls were bonded near aluminum sites of the zeolite, as shown by the decrease in intensity of the IR bands characterizing the acidic silanol groups resulting from the reaction of the rhenium carbonyl with the zeolite. This supported metal complex was characterized by narrow peaks in the ν(CO) region of the IR spectrum, indicating highly uniform species. In contrast, the species formed from CH(3)Re(CO)(5) on NaY zeolite lost fewer carbonyl ligands than those formed on HY zeolite and were significantly less uniform, as indicated by the greater breadth of the ν(CO) bands in the IR spectra. The results show the importance of zeolite H(+) sites for the formation of uniform supported rhenium carbonyls from CH(3)Re(CO)(5); the formation of such uniform complexes did not occur on the NaY zeolite.

Physicochemical regeneration of high silica zeolite Y used to clean-up water polluted with sulfonamide antibiotics.

PubMed

Braschi, I; Blasioli, S; Buscaroli, E; Montecchio, D; Martucci, A

2016-05-01

High silica zeolite Y has been positively evaluated to clean-up water polluted with sulfonamides, an antibiotic family which is known to be involved in the antibiotic resistance evolution. To define possible strategies for the exhausted zeolite regeneration, the efficacy of some chemico-physical treatments on the zeolite loaded with four different sulfonamides was evaluated. The evolution of photolysis, Fenton-like reaction, thermal treatments, and solvent extractions and the occurrence in the zeolite pores of organic residues eventually entrapped was elucidated by a combined thermogravimetric (TGA-DTA), diffractometric (XRPD), and spectroscopic (FT-IR) approach. The chemical processes were not able to remove the organic guest from zeolite pores and a limited transformation on embedded molecules was observed. On the contrary, both thermal treatment and solvent extraction succeeded in the regeneration of the zeolite loaded from deionized and natural fresh water. The recyclability of regenerated zeolite was evaluated over several adsorption/regeneration cycles, due to the treatment efficacy and its stability as well as the ability to regain the structural features of the unloaded material. Copyright © 2015. Published by Elsevier B.V.

A comparison of the amorphization of zeolitic imidazolate frameworks (ZIFs) and aluminosilicate zeolites by ball-milling.

PubMed

Baxter, Emma F; Bennett, Thomas D; Cairns, Andrew B; Brownbill, Nick J; Goodwin, Andrew L; Keen, David A; Chater, Philip A; Blanc, Frédéric; Cheetham, Anthony K

2016-03-14

X-ray diffraction has been used to investigate the kinetics of amorphization through ball-milling at 20 Hz, for five zeolitic imidazolate frameworks (ZIFs) - ZIF-8, ZIF-4, ZIF-zni, BIF-1-Li and CdIF-1. We find that the rates of amorphization for the zinc-containing ZIFs increase with increasing solvent accessible volume (SAV) in the sequence ZIF-8 > ZIF-4 > ZIF-zni. The Li-B analogue of the dense ZIF-zni amorphizes more slowly than the corresponding zinc phase, with the behaviour showing a correlation with their relative bulk moduli and SAVs. The cadmium analogue of ZIF-8 (CdIF-1) amorphizes more rapidly than the zinc counterpart, which we ascribe primarily to its relatively weak M-N bonds as well as the higher SAV. The results for the ZIFs are compared to three classical zeolites - Na-X, Na-Y and ZSM-5 - with these taking up to four times longer to amorphize. The presence of adsorbed solvent in the pores is found to render both ZIF and zeolite frameworks more resistant to amorphization. X-ray total scattering measurements show that amorphous ZIF-zni is structurally indistinguishable from amorphous ZIF-4 with both structures retaining the same short-range order that is present in their crystalline precursors. By contrast, both X-ray total scattering measurements and (113)Cd NMR measurements point to changes in the local environment of amorphous CdIF-1 compared with its crystalline CdIF-1 precursor.

Reduced Performance of Prey Targeting in Pit Vipers with Contralaterally Occluded Infrared and Visual Senses

PubMed Central

Chen, Qin; Deng, Huanhuan; Brauth, Steven E.; Ding, Li; Tang, Yezhong

2012-01-01

Both visual and infrared (IR) senses are utilized in prey targeting by pit vipers. Visual and IR inputs project to the contralateral optic tectum where they activate both multimodal and bimodal neurons. A series of ocular and pit organ occlusion experiments using the short-tailed pit viper (Gloydius brevicaudus) were conducted to investigate the role of visual and IR information during prey targeting. Compared with unoccluded controls, snakes with either both eyes or pit organs occluded performed more poorly in hunting prey although such subjects still captured prey on 75% of trials. Subjects with one eye and one pit occluded on the same side of the face performed as well as those with bilateral occlusion although these subjects showed a significant targeting angle bias toward the unoccluded side. Performance was significantly poorer when only a single eye or pit was available. Interestingly, when one eye and one pit organ were occluded on opposite sides of the face, performance was poorest, the snakes striking prey on no more than half the trials. These results indicate that, visual and infrared information are both effective in prey targeting in this species, although interference between the two modalities occurs if visual and IR information is restricted to opposite sides of the brain. PMID:22606229

Surfactant modified zeolite as amphiphilic and dual-electronic adsorbent for removal of cationic and oxyanionic metal ions and organic compounds.

PubMed

Tran, Hai Nguyen; Viet, Pham Van; Chao, Huan-Ping

2018-01-01

A hydrophilic Y zeolite was primarily treated with sodium hydroxide to enhance its cation exchange capacity (Na-zeolite). The organo-zeolite (Na-H-zeolite) was prepared by a modification process of the external surface of Na-zeolite with a cationic surfactant (hexadecyltrimethylammonium; HDTMA). Three adsorbents (i.e., pristine zeolite, Na-zeolite, and Na-H-zeolite) were characterized with nitrogen adsorption/desorption isotherms, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, cation exchange capacities, and zeta potential. Results demonstrated that HDTMA can be adsorbed on the surface of Na-zeolite to form patchy bilayers. The adsorption capacity of several hazardous pollutants (i.e., Pb 2+ , Cu 2+ , Ni 2+ , Cr 2 O 7 2- , propylbenzene, ethylbenzene, toluene, benzene, and phenol) onto Na-H-zeolite was investigated in a single system and multiple-components. Adsorption isotherm was measured to further understand the effects of the modification process on the adsorption behaviors of Na-H-zeolite. Adsorption performances indicated that Na-H-zeolite can simultaneously adsorb the metal cations (on the surface not covered by HDTMA), oxyanions (on the surface covered by HDTMA). Na-H-zeolite also exhibited both hydrophilic and hydrophobic surfaces to uptake organic compounds with various water solubilities (from 55 to 75,000mg/L). It was experimentally concluded that Na-H-zeolite is a potential dual-electronic and amphiphilic adsorbent for efficiently removing a wide range of potentially toxic pollutants from aquatic environments. Copyright © 2017 Elsevier Inc. All rights reserved.

Zeolite formation from coal fly ash and its adsorption potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duangkamol Ruen-ngam; Doungmanee Rungsuk; Ronbanchob Apiratikul

The possibility in converting coal fly ash (CFA) to zeolite was evaluated. CFA samples from the local power plant in Prachinburi province, Thailand, were collected during a 3-month time span to account for the inconsistency of the CFA quality, and it was evident that the deviation of the quality of the raw material did not have significant effects on the synthesis. The zeolite product was found to be type X. The most suitable weight ratio of sodium hydroxide (NaOH) to CFA was approximately 2.25, because this gave reasonably high zeolite yield with good cation exchange capacity (CEC). The silica (Si)-to-aluminummore » (Al) molar ratio of 4.06 yielded the highest crystallinity level for zeolite X at 79% with a CEC of 240 meq/100 g and a surface area of 325 m{sup 2}/g. Optimal crystallization temperature and time were 90{sup o}C and 4 hr, respectively, which gave the highest CEC of approximately 305 meq/100 g. Yields obtained from all experiments were in the range of 50-72%. 29 refs., 5 tabs., 7 figs.« less

Zeolites in Eocene basaltic pillow lavas of the Siletz River Volcanics, Central Coast Range, Oregon

USGS Publications Warehouse

Keith, Terry E.C.; Staplese, Lloyd W.

1985-01-01

Zeolites and associated minerals occur in a tholeiitic basaltic pillow lava sequence that makes up part of the Eocene Siletz River Volcanics in the central Coast Range, Oregon. Regional zoning of zeolite assemblages is not apparent; the zeolites formed in joints, fractures, and interstices, although most occur in central cavities of basalt pillows. The zeolites and associated minerals identified, in general order of paragenetic sequence, are smectite, pyrite, calcite (small spheres), thomsonite, natrolite, analcime, scolecite, mesolite, stilbite, heulandite, apophyllite, chahazite, mordenite, calcite (scalenohedra and twinned rhombohedra), laumontite, and amethystine quartz. Common three-mineral assemblages are: natrolite-analcime-sfilbite, stilbite-heulandite-chabazite, stilbite-apophyllie-chabazite, and natrolite-mesolite-laumontite.Alteration of basaltic glass, which was initially abundant, appears to have been an important factor in formation of the zeolites. Isotopic data suggest that zeolitization occurred during a low-temperature (60 ~ 70°C submarine hydrothermal event, or by reactions of cold (~ 10°C meteoric water with basalt over a long time. The occurrence of different mineral assemblages in cavities of adjacent basalt pillows indicates that these minerals crystallized in dosed systems that were isolated as fractures and joints were sealed by deposition of smectite and early zeolites. Although the total chemical composition of the mineral assemblages in cavities is similar, different mineral species formed because of the sensitivity of zeolite minerals to slight variations in physical and chemical conditions within individual cavities.

[Effect of Nano Zeolite on Chemical Fractions of Cd in Soil and Its Uptake by Cabbage].

PubMed

Xiong, Shi-juan; Xu, Wei-hong; Xie, Wen-wen; Chen, Rong; Chen, Yong-qin; Chi, Sun-lin; Chen, Xu- gen; Zhang, Jin-zhong; Xiong, Zhi-ting; Wang, Zheng-yin; Xie, De-ti

2015-12-01

Incubation experiments were carried out to investigate the influence of different nano zeolite (NZ) and ordinary zeolite (OZ) levels(0, 5, 10 and 20 g · kg⁻¹) on the change trends in fraction distribution coefficient (FDC) of Cd when exposed to different Cadmium (Cd) levels (1, 5, 10 and 15 mg · kg⁻¹), and pot experiments were carried out to investigate their influence on soil Cd fraction and Cd uptake by cabbage. The results in incubation experiments showed that the application of nano zeolite as well as ordinary zeolite effectively decreased the FDC of exchangeable Cd and increased the FDC of Fe-Mn oxide fraction. The FDC of soil Cd from 0 d to 28 d was deceased at first, then increased and tended to be stable, and finally increased. At the end of incubation, the FDC of soil exchangeable Cd decreased from 72.0%-88.0% to 30.0%-66.4%. Exchangeable fraction Cd was the most dominant Cd fraction in soil during the whole incubation. The results in pot experiment indicated that the application of nano zeolite and ordinary zeolite decreased the concentration and FDC of soil exchangeable Cd, and concurrently the concentration and FDC of Cd in carbonate, Fe-Mn oxide, organic matter and residual fraction were increased. The lowest EX-Cd was observed in the treatment with high dose of nano zeolite (20 g · kg⁻¹). The FDC of exchangeable Cd showed significant negative relationship with the soil pH (P < 0.05), and was concurrently extremely positively correlated with Cd concentration in shoot and root of cabbage (P < 0.01). Soil pH increased by 1.8%-45.5% and 6.1%-54.3% in the presence of zeolite when exposed to 5 mg · kg⁻¹ 1 and Cd, respectively; FDC of exchangeable Cd decreased by 16.3%-47.7% and 16.2%-46.7%; Cd concentration in each tissues of cabbage decreased by 1.0%-75.0% and 3.8%-53.2%, respectively. Moreover, the reduction effect of nano zeolite on soil and plant Cd was better than that of ordinary zeolite. The growth of cabbage was stimulated by low and

IR and NMR studies of hierarchical material obtained by the treatment of zeolite Y by ammonia solution

NASA Astrophysics Data System (ADS)

Gackowski, Mariusz; Kuterasiński, Łukasz; Podobiński, Jerzy; Sulikowski, Bogdan; Datka, Jerzy

2018-03-01

Ammonia treatment of ultrastable zeolite Y has a great impact on its features. XRD showed a partial loss of crystallinity coupled with a loss of long-distance zeolite ordering. However, a typical short-range zeolite ordering, in the light of 29Si NMR studies, was largely preserved. 27Al MAS NMR spectra evidenced that most of Al was located in zeolitic tetrahedral positions, but some of them adopted a distorted configuration. Evolution of zeolites acidity was followed quantitatively by using IR. In particular, such studies revealed the presence of strongly acidic Sisbnd OHsbnd Al groups. IR studies suggest also heterogeneity of these OH groups. The heterogeneity of Sisbnd OHsbnd Al groups was a consequence of the less ordered structure of zeolites treated with ammonia solutions. It was also found that the treatment with ammonia solutions yields hierarchical material. The samples revealed promising catalytic properties in the liquid phase isomerization of α-pinene. Zeolites desilicated with ammonia may constitute an inexpensive route yielding viable hierarchical catalysts.

Synthesis and characterization of zeolites prepared from industrial fly ash.

PubMed

Franus, Wojciech; Wdowin, Magdalena; Franus, Małgorzata

2014-09-01

In this paper, we present the possibility of using fly ash to produce synthetic zeolites. The synthesis class F fly ash from the Stalowa Wola SA heat and power plant was subjected to 24 h hydrothermal reaction with sodium hydroxide. Depending on the reaction conditions, three types of synthetic zeolites were formed: Na-X (20 g fly ash, 0.5 dm(3) of 3 mol · dm(-3) NaOH, 75 °C), Na-P1 (20 g fly ash, 0.5 dm(3) of 3 mol · dm(-3) NaOH, 95 °C), and sodalite (20 g fly ash, 0.8 dm(3) of 5 mol · dm(-3) NaOH + 0.4 dm(3) of 3 mol · dm(-3) NaCl, 95 °C). As synthesized materials were characterized to obtain mineral composition (X-ray diffractometry, Scanning electron microscopy-energy dispersive spectrometry), adsorption properties (Brunauer-Emmett-Teller surface area, N2 isotherm adsorption/desorption), and ion exchange capacity. The most effective reaction for zeolite preparation was when sodalite was formed and the quantitative content of zeolite from X-ray diffractometry was 90 wt%, compared with 70 wt% for the Na-X and 75 wt% for the Na-P1. Residues from each synthesis reaction were the following: mullite, quartz, and the remains of amorphous aluminosilicate glass. The best zeolitic material as characterized by highest specific surface area was Na-X at almost 166 m(2) · g(-1), while for the Na-P1 and sodalite it was 71 and 33 m(2) · g(-1), respectively. The ion exchange capacity decreased in the following order: Na-X at 1.8 meq · g(-1), Na-P1 at 0.72 meq · g(-1), and sodalite at 0.56 meq · g(-1). The resulting zeolites are competitive for commercially available materials and are used as ion exchangers in industrial wastewater and soil decontamination.

Removal of nickel from aqueous solution using supported zeolite-Y hollow fiber membranes.

PubMed

Muhamad, Norfazilah; Abdullah, Norfazliana; Rahman, Mukhlis A; Abas, Khairul Hamimah; Aziz, Azian Abd; Othman, Mohd Hafiz Dzarfan; Jaafar, Juhana; Ismail, Ahmad Fauzi

2018-05-02

This work describes the development of supported zeolite-Y membranes, prepared using the hydrothermal method, for the removal of nickel from an aqueous solution. Alumina hollow fibers prepared using the phase inversion and sintering technique were used as an inert support. The supported zeolite-Y membranes were characterized using the field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and the water permeation and rejection test. The performance of the supported zeolite-Y membranes for heavy metal removal using batch adsorption and filtration test was studied using the atomic absorption spectroscopy (AAS). The adsorption study shows that the removal of nickel was pH-dependent but affected by the presence of α-alumina. The seeded zeolite-Y membrane gave the highest adsorption capacity which was 126.2 mg g -1 . This enabled the membrane to remove 63% of nickel ions from the aqueous solution within 180 min of contact time. The adsorption mechanism of nickel onto the zeolite-Y membrane was best fitted to the Freundlich isotherm. The kinetic study concluded that the adsorption was best fitted to pseudo-second-order model with higher correlation coefficient (R 2  = 0.9996). The filtration study proved that the zeolite-Y membrane enabled to reduce the concentration of heavy metal at parts per billion level.

Synthesis and characterization of Sn/zeolite and catalytic activity test in the esterification reaction of sludge oil

NASA Astrophysics Data System (ADS)

Alimuddin, Andi Hairil; Usman, Thamrin; Wahyuni, Nelly; Rudiyansyah, Prawatya, Yopa Eka; Astar, Ismail; Yustira, Yudi

2017-03-01

Synthesis of Sn-Zeolite has been made to use for esterification reaction of free fatty acids in sludge oil. Catalyst characterization was accomplished using X-Ray Diffraction (XRD), X-Ray Flourecence (XRF), and Fourier Transform Infra Red (FTIR). Catalyst Sn/zeolite was synthesized by impregnated Sn of SnCl2 into the zeolite. The amount of Sn impregnated base on the value of cation exchange capacity (CEC) of zeolites. Esterification reaction of fatty acids from sludge oil using Sn/Zeolite catalyst was did by variated the reaction time. XRD analysis results showed that the catalyst Sn/zeolite was dominated by modernit and quartz. XRF analysis results was increasing amount of Sn metal and the Si/Al ratio on Sn/zeolite catalyst along with addition of Sn metal. FTIR analysis results showed that the catalyst synthesized had Bronsted acid side (the spectrum 1639.4; 1656.7; 1654.8 cm-1) and the Lewis acid (spectrum 1400.2 and 1402.2 cm-1). The results showed that the optimum conditions of esterification reaction in 4 hours reaction time, 5% concentration of the catalyst, and molar ratio was about 1:10 with a conversion percentage of products reached 96.00%, which can be achieved with a ratio was about 4:1 between Sn and zeolite on Sn/zeolite catalyst.

Conductivity in zeolite-polymer composite membranes for PEMFCs

NASA Astrophysics Data System (ADS)

Sancho, T.; Soler, J.; Pina, M. P.

Structured materials, such as zeolites can be candidates to be used as electrolytes in proton exchange membrane fuel cells (PEMFC) to substitute polymeric membranes, taking advantage of their higher chemical and thermal stability and their specific adsorption properties. The possibility to work at temperatures of nearly 150 °C would make easy the selection of the fuel, decreasing the influence of CO in the catalyst poisoning, and it would also improve the kinetics of the electrochemical reactions involved. In this work, four zeolites and related materials have been studied: mordenite, NaA zeolite, umbite and ETS-10. In special, the influence of relative humidity and temperature have been carefully explored. A conductivity cell was designed and built to measure in cross direction, by using the electrochemical impedance spectroscopy. The experimental system was validated using Nafion ® as a reference material by comparing the results with bibliography data. Samples were prepared by pressing the zeolite powders, with size of 1 μm on average, using polymer PVDF (10 wt.%) as a binder. The results here obtained, in spite of not reaching the absolute values of the Nafion ® ones, show a lower effect of the dehydration phenomenon on the conduction performance in the temperature range studied (from room temperature to 150 °C). This increase of the operation temperature range would give important advantages to the PEMFC. ETS-10 sample shows the best behaviour with respect to conductivity exhibiting an activation energy value comparable with reported for Nafion ® membrane.

A Laboratory Study of Natural Zeolite for Treatment of Fluorinated Water

NASA Astrophysics Data System (ADS)

Pandey, A.

2015-12-01

Fluoride contamination is mainly induced in ground water by chemical interaction between water and fluoride bearing rocks and natural fluoridation is further catalyzed by anthropogenic activities. Elevated fluoride concentrations in the water bodies above the permissible limits are not only degrading water for drinking purposes but also to the agricultural, industrial as well as daily household needs. Fluoride content in water has been constantly a subject of serious concern to the concerned authorities. It is significantly contributing in increasing tolls of arthritis, brain and kidney diseases, cancer, male fertility issues and cases of thyroid diseases. Hence, the present study has been conducted to investigate the possibility of treating fluorinated water using zeolites. The capabilities of natural zeolites are attributed to their catalytic, molecular sieve, adsorption and ion-exchange properties which have been utilized in our laboratory experiment. The experiment was carried out in two phases. In the first phase of the experiment, the properties of zeolites were tested in solid and liquid phases using ICP-OES, SEM, EDX and IC tests. Physio-chemical alterations induced by zeolites in the fluid chemistry were monitored by analyzing fluid sample regularly for pH, redox potential, electrical conductivity and total dissolved solids, and by conducting metal and anion tests. In second phase, zeolite was used for treatment of fluorinated water with known concentration of fluoride, and the geochemical processes associated with fluoride remediation were monitored by conducting non-invasive, invasive geochemical and physical measurements at regular time periods on the water samples collected from both control column and the experiment column. Results thus obtained in this study showed decrease in fluoride concentration over time, indicating the possibility of use of zeolites in treatment of fluorinated water.

Nanoassembled dynamic optical waveguides and sensors based on zeolite L nanocontainers

NASA Astrophysics Data System (ADS)

Barroso, Álvaro; Dieckmann, Katrin; Alpmann, Christina; Buscher, Tim; Studer, Armido; Denz, Cornelia

2015-03-01

Although optical functional devices as waveguides and sensors are of utmost importance for metrology on the nano scale, the micro-and nano-assembly by optical means of functional materials to create such optical elements has yet not been considered. In the last years, an elegant strategy based on holographic optical tweezers (HOT) has been developed to design and fabricate permanent and dynamic three-dimensional micro- and nanostructures based on functional nanocontainers as building blocks. Nanocontainers that exhibit stable and ordered voids to hierarchically organize guest materials are especially attractive. Zeolite L are a type of porous micro-sized crystals which features a high number of strictly one-dimensional, parallel aligned nanochannels. They are highly interesting as building blocks of functional nano-and microsystems due to their potential as nanocontainers to accommodate various different guest molecules and to assemble them in specific configurations. For instance, based on zeolite L crystals, microscopic polarization sensors and chains of several microcrystals for hierarchical supramolecular organization have been realized. Here, we demonstrate the ability of nanocontainers in general, and zeolite L crystals in particular to represent the basic constituent of optical functional microsystems. We show that the capability of HOT to manipulate multitude of non-spherical microparticles in three dimensions can be exploited for the investigation of zeolite L nanocontainers as dynamic optical waveguides. Moreover, we implement as additional elements dye-loaded zeolite L to sense the guiding features of these novel waveguides with high spatial precision and microspheres to enhance the light coupling into the zeolite L waveguides. With this elaborated approach of using nanocontainers as tailored building blocks for functional optical systems a new era of bricking optical components in a lego-like style becomes feasible.

Adsorption of nicotine from aqueous solution onto hydrophobic zeolite type USY

NASA Astrophysics Data System (ADS)

Lazarevic, Natasa; Adnadjevic, Borivoj; Jovanovic, Jelena

2011-07-01

The isothermal adsorption of nicotine from an aqueous solution onto zeolite type USY was investigated. The adsorption isotherms of nicotine onto the zeolite at different temperatures ranging from 298 to 322 K were determined. It was found that the adsorption isotherms can be described by the model of Freundlich adsorption isotherm. Based on the adsorption isotherms the changes of adsorption heat, free energy and entropy with adsorption degree were determined. The determined decrease of adsorption heat with adsorption degree can be explained by the presence of the adsorption centers of different energy and concentration on interface of zeolite-nicotine solution. It was found that the probability function of density distribution of the heat of adsorption (DDF) has exponential form. It was concluded that the possibility of fitting the adsorption isotherms of nicotine onto the zeolite by Freundlich adsorption isotherm was a direct consequence of that. The determined increase in entropy with the increase in adsorption degree can be explained with the change of phase state of adsorbed nicotine.

A long-term study examining the antibacterial effectiveness of Agion silver zeolite technology on door handles within a college campus.

PubMed

Potter, B A; Lob, M; Mercaldo, R; Hetzler, A; Kaistha, V; Khan, H; Kingston, N; Knoll, M; Maloy-Franklin, B; Melvin, K; Ruiz-Pelet, P; Ozsoy, N; Schmitt, E; Wheeler, L; Potter, M; Rutter, M A; Yahn, G; Parente, D H

2015-02-01

Laboratory studies have shown that small concentrations of silver are effective at inhibiting the growth micro-organisms through the disruption of important cell structures and processes. The additional ability to incorporate silver into surfaces has increased the usage of silver in the medical field and expanded its use into the consumer market. To understand the impact of increased silver-containing antimicrobial use, it is important to determine whether silver-based consumer goods are effective at reducing bacterial populations. Our study examined the antibacterial effectiveness of Agion silver zeolite technology applied to 25 silver- and control-coated door handles across a college campus. Door handles were sampled for 6 week periods in both the fall and spring semester, and bacteria were cultured and enumerated on tryptic soy agar (TSA), MacConkey agar (MAC) and mannitol salt agar (MSA). A significant difference was observed between the bacterial populations isolated from silver- and control-coated door handles after 3 years. However, bacteria were consistently isolated from silver-coated door handles suggesting that the silver zeolite was only effective against a portion of the bacterial populations, and further studies are necessary to determine the identities of the isolated bacteria and the prevalence of silver resistance. © 2014 The Society for Applied Microbiology.

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.

A Highly Ion-Selective Zeolite Flake Layer on Porous Membranes for Flow Battery Applications.

PubMed

Yuan, Zhizhang; Zhu, Xiangxue; Li, Mingrun; Lu, Wenjing; Li, Xianfeng; Zhang, Huamin

2016-02-24

Zeolites are crystalline microporous aluminosilicates with periodic arrangements of cages and well-defined channels, which make them very suitable for separating ions of different sizes, and thus also for use in battery applications. Herein, an ultra-thin ZSM-35 zeolite flake was introduced onto a poly(ether sulfone) based porous membrane. The pore size of the zeolite (ca. 0.5 nm) is intermediary between that of hydrated vanadium ions (>0.6 nm) and protons (<0.24 nm). The resultant membrane can thus be used to perfectly separate vanadium ions and protons, making this technology useful in vanadium flow batteries (VFB). A VFB with a zeolite-coated membrane exhibits a columbic efficiency of >99 % and an energy efficiency of >81 % at 200 mA cm(-2), which is by far the highest value ever reported. These convincing results indicate that zeolite-coated membranes are promising in battery applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of sodium loading on zeolite support for catalyzed transesterification of triolein with methanol.

PubMed

Wang, Yu-Yuan; Chou, Hsin-Yu; Chen, Bing-Hung; Lee, Duu-Jong

2013-10-01

Optimization of sodium loading on zeolite HY for catalyzed transesterification of triolein in excess methanol to biodiesel was studied. Zeolite HY catalyst was activated by loading sodium ions to their surface via an ion-exchange method. The effects of ion-exchange process parameters, including the temperature, the process time, the pH value, as well as concentrations and sources of Na(+) cations (NaOH, NaCl and Na2SO4), on the conversion yield of triolein to biodiesel were investigated. Most of these Na(+)-activated zeolite HY catalysts could really facilitate the catalyzed transesterification reaction of triolein to biodiesel at a lower temperature near 65°C. Consequently, a high conversion yield of triglycerides to biodiesel at 97.3% was obtained at 65°C. Moreover, the durability of zeolite catalysts was examined as well. Catalytic performance tests of these zeolite catalysts in transesterification did not show a significant decrease in catalysis at least for three batch cycles. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluation of Zeolite Permeable Treatment Wall for the Removal of Strontium-90 from Groundwater

NASA Astrophysics Data System (ADS)

Seneca, S. M.; Bandilla, K.; Rabideau, A. J.; Ross, E.; Bronner, C. E.

2009-12-01

Experimental and modeling studies are in progress to evaluate the potential performance of a permeable treatment wall comprised of zeolite-rich rock for the removal of strontium-90 from groundwater. Column studies were performed using a synthetic groundwater referenced to anticipate field conditions, with a focus on quantifying the competitive ion exchange among five cations (Na+, K+, Ca2+, Mg2+, and Sr2+). Ongoing studies are focused on the comparison of zeolites obtained from two sources: Teague Mineral Products (Adrian, OR) and Bear River Zeolite (Preston, UT), and on the possible influence of native soil that is mixed with treatment wall material during construction. The data obtained from the column studies is used to support robust estimation of zeolite cation exchange parameters producing a five-solute cation exchange model describing the removal efficiency of the zeolite. The field-scale transport model provides flexibility to explore design parameters to support the possible deployment of a full scale treatment wall at a Western New York nuclear facility.

A mesostructured Y zeolite as a superior FCC catalyst--lab to refinery.

PubMed

García-Martínez, Javier; Li, Kunhao; Krishnaiah, Gautham

2012-12-18

A mesostructured Y zeolite was prepared by a surfactant-templated process at the commercial scale and tested in a refinery, showing superior hydrothermal stability and catalytic cracking selectivity, which demonstrates, for the first time, the promising future of mesoporous zeolites in large scale industrial applications.

Adsorption interaction in the molecular hydrogen-aluminophosphate AlPO-5 zeolite system

NASA Astrophysics Data System (ADS)

Grenev, I. V.; Gavrilov, V. Yu.

2015-03-01

The adsorption interaction between molecular hydrogen and atoms forming the lattice of AlPO-5 zeolite is studied. The potential of intramolecular interaction is calculated by summing the potentials of individual pairwise H2-O(Al, P) interactions in a fragment of the zeolite structure with a volume of ˜32 nm3. Isopotential surfaces are constructed that allow determination of the shape of zeolite microchannels and the places of the preferential localization of sorbate molecules in the porous space. The calculated and experimental values of the Henry constant of H2 adsorption on AlPO-5 at 77 K are compared.

One-pot pseudomorphic crystallization of mesoporous porous silica to hierarchical porous zeolites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing, Jun-Ling; Jiang, Shu-Hua; Pang, Jun-Ling

2015-09-15

Hierarchically porous silica with mesopore and zeolitic micropore was synthesized via pseudomorphic crystallization under high-temperature hydrothermal treatment in the presence of cetyltrimethylammonium tosylate and tetrapropylammonium ions. A combined characterization using small-angle X-ray diffraction (XRD), nitrogen adsorption, high-resolution transmission electron microscopy (TEM), thermogravimetric analysis (TG), and elemental analysis showed that dual templates, CTA{sup +} and TPA{sup +} molecules, can work in a cooperative manner to synthesize mesoporous zeolite in a one-pot system by precisely tuning the reaction conditions, such as reaction time and temperature, and type and amount of heterometal atoms. It is found that the presence of Ti precursor ismore » critical to the successful synthesis of such nanostructure. It not only retards the nucleation and growth of crystalline MFI domains, but also acts as nano-binder or nano-glue to favor the assembly of zeolite nanoblocks. - Graphical abstract: Display Omitted - Highlights: • A facile method to synthesize mesoporous zeolites with hierarchical porosity was presented. • It gives a new insight into keeping the balance between mesoscopic and molecular ordering in hierarchical porous materials. • A new understanding on the solid–solid transformation mechanism for the synthesis of titanosilicate zeolites was proposed.« less

The energetics of mesopore formation in zeolites with surfactants.

PubMed

Linares, Noemi; Jardim, Erika de Oliveira; Sachse, Alexander; Serrano, Elena; Garcia-Martinez, Javier

2018-05-02

Mesoporosity can be conveniently introduced in zeolites by treating them in basic surfactant solutions. The apparent activation energy involved in the formation of mesopores in USY via surfactant-templating was obtained through the combination of in situ synchrotron XRD and ex situ gas adsorption. Additionally, techniques such as pH measurements and TG/DTA were employed to determine the OH- evolution and the CTA+ uptake during the development of mesoporosity, providing information about the different steps involved. By combining both in situ and ex situ techniques, we have been able, for the first time, to determine the apparent activation energies of the different processes involved in the mesostructuring of USY zeolites, which are in the same order of magnitude (30 - 65 kJ mol-1) of those involved in the crystallization of zeolites. Hence, important mechanistic insights on the surfactant-templating method were obtained. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Predictive framework for shape-selective separations in three-dimensional zeolites and metal-organic frameworks.

PubMed

First, Eric L; Gounaris, Chrysanthos E; Floudas, Christodoulos A

2013-05-07

With the growing number of zeolites and metal-organic frameworks (MOFs) available, computational methods are needed to screen databases of structures to identify those most suitable for applications of interest. We have developed novel methods based on mathematical optimization to predict the shape selectivity of zeolites and MOFs in three dimensions by considering the energy costs of transport through possible pathways. Our approach is applied to databases of over 1800 microporous materials including zeolites, MOFs, zeolitic imidazolate frameworks, and hypothetical MOFs. New materials are identified for applications in gas separations (CO2/N2, CO2/CH4, and CO2/H2), air separation (O2/N2), and chemicals (propane/propylene, ethane/ethylene, styrene/ethylbenzene, and xylenes).

Elimination of Escherichia coli and Salmonella in Clam by Using Zeolite in a Station of Depuration.

PubMed

Gdoura, Morsi; Sellami, Hanen; Khannous, Lamia; Ketata, Najib; Neila, Idriss Ben; Traore, Al Ibrahim; Chekir, Zouhair; Gdoura, Radhouane

2017-09-01

  The application of natural zeolite for water and wastewater treatment has been carried out and is still a promising technique in environmental cleaning processes. Natural zeolite can be used to improve the purification process of clams (Ruditapes decussatus). Thus, our study aimed at improving the clam purification system in order to reduce Escherichia coli and eliminate Salmonella in samples artificially contaminated with this bacterium using a natural zeolite to replace the biological filter. The results showed that zeolite used in a depuration system improved the clam purification process. Moreover, natural zeolite exhibited high performance in the adsorption of bacteria and allowed to reduce the Escherichia coli abundance in 24 h, thus ensuring purified clams conformity with the ISO 16649-3 standard. These results indicate the beneficial effects of using zeolite in the adsorption of bacteria and the reduction in the abundance of Escherichia coli and set the Salmonella from marine organisms.

Dispersion enhanced metal/zeolite catalysts

DOEpatents

Sachtler, W.M.H.; Tzou, M.S.; Jiang, H.J.

1987-03-31

Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

Dispersion enhanced metal/zeolite catalysts

DOEpatents

Sachtler, Wolfgang M. H.; Tzou, Ming-Shin; Jiang, Hui-Jong

1987-01-01

Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

History and utility of zeolite framework-type discovery from a data-science perspective

DOE PAGES

Zimmermann, Nils E. R.; Haranczyk, Maciej

2016-05-02

Mature applications such as fluid catalytic cracking and hydrocracking rely critically on early zeolite structures. With a data-driven approach, we find that the discovery of exceptional zeolite framework types around the new millennium was spurred by exciting new utilization routes. The promising processes have yet not been successfully implemented (“valley of death” effect), mainly because of the lack of thermal stability of the crystals. As a result, this foreshadows limited deployability of recent zeolite discoveries that were achieved by novel crystal synthesis routes.

Preparation and characterization of polysulfone/zeolite mixed matrix membranes for removal of low-concentration ammonia from aquaculture wastewater.

PubMed

Moradihamedani, Pourya; Abdullah, Abdul Halim

2018-01-01

Removal of low-concentration ammonia (1-10 ppm) from aquaculture wastewater was investigated via polysulfone (PSf)/zeolite mixed matrix membrane. PSf/zeolite mixed matrix membranes with different weight ratios (90/10, 80/20, 70/30 and 60/40 wt.%) were prepared and characterized. Results indicate that PSf/zeolite (80/20) was the most efficient membrane for removal of low-concentration ammonia. The ammonia elimination by PSf/zeolite (80/20) from aqueous solution for 10, 7, 5, 3 and 1 ppm of ammonia was 100%, 99%, 98.8%, 96% and 95% respectively. The recorded results revealed that pure water flux declined in higher loading of zeolite in the membrane matrix due to surface pore blockage caused by zeolite particles. On the other hand, ammonia elimination from water was decreased in higher contents of zeolite because of formation of cavities and macrovoids in the membrane substructure.

Experimental study on the adsorptive-distillation for dehydration of ethanol-water mixture using natural and synthetic zeolites

NASA Astrophysics Data System (ADS)

Megawati, Wicaksono, D.; Abdullah, M. S.

2017-03-01

This research studied adsorptive-distillation (AD) for dehydration of ethanol-water mixture using natural and synthetic zeolites as adsorbent for ethanol purification. Especially, the effect of purification time is recorded and studied to evaluate performance of designed AD equipment. This AD was performed in a batch condition using boiling flask covered with heating mantle and it was maintained at 78°C temperature and 1 atm pressure. The initial ethanol volume was 300 mL with 93.8% v/v concentration. The synthetic zeolite type used was zeolite 3A. The flowed vapour was condensed using water as a cooling medium. Every 5 minutes of time duration the samples were collected until the vapour could not be condensed in that condition and then be analyzed its concentration using Gas-Chromatography. Experiment shows that the designed AD equipment could increase ethanol concentration at first 5 minutes with highest ethanol concentration achieved using synthetic zeolite (97.47% v/v). However, ethanol concentration from AD process using natural zeolite only reached 96.5% v/v. Thus, synthetic zeolite as adsorbent could pass azeotropic point, but natural zeolite fail. The ratio of adsorbed water per adsorbent for natural and synthetic zeolites are about 0.023 and 0.056 gwater/gads, respectively, at 50 minutes of time. Finally, synthetic zeolite (at 55 minutes the value of C/C0 is about 0.85 and the average outlet water concentration is 4.70 mole/L) as adsorbent for AD of ethanol water is better than natural zeolite (at 55 minutes the value of C/C0 is about 0.63 and the average outlet water concentration is 6.43 mole/L).

Exploring Mass Transfer in Mesoporous Zeolites by NMR Diffusometry

PubMed Central

Mehlhorn, Dirk; Valiullin, Rustem; Kärger, Jörg; Cho, Kanghee; Ryoo, Ryong

2012-01-01

With the advent of mesoporous zeolites, the exploration of their transport properties has become a task of primary importance for the auspicious application of such materials in separation technology and heterogeneous catalysis. After reviewing the potential of the pulsed field gradient method of NMR (PFG NMR) for this purpose in general, in a case study using a specially prepared mesoporous zeolite NaCaA as a host system and propane as a guest molecule, examples of the attainable information are provided. PMID:28817004

Microwave pyrolysis of multilayer plastic waste (LDPE) using zeolite catalyst

NASA Astrophysics Data System (ADS)

Juliastuti, Sri Rachmania; Hendrianie, Nuniek; Ramadhan, Pandu Jati; Satria, Dama Husin

2017-05-01

To overcome the problem of garbage, especially plastic waste, environmental experts and scholars from various disciplines have conducted various studies and actions. One way to degrade the multilayer packaging plastic waste LDPE (Low Density Poliethylene) with microwave pyrolysis process by using natural zeolite catalysts. The purpose of this experiment was to determine the effect of temperature and time of microwave pyrolysis process by using natural zeolite catalyst to degrade the plastic waste LDPE and compare them. Pyrolysis process was done by using a closed glass reactor with a capacity of 500 ml, operated at a pressure of 1 atm and flowed nitrogen 0.5 1 / min. Plastic waste was LDPE, and natural zeolite was used as its catalyst. Sample was heated at temperature 300, 400, 500 or 550 °C and was kept during time variables of 45, 60, 75 and 90 minutes. Liquid product was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS), raw material was analyzed by Fourier Transform Infrared (FTIR), and solid product was analyzed by X-Ray Fluorescene (XRF). From the experimental resulted in the best yield products of pyrolisis using natural zeolite at 550 °C and 90 minutes was 2.88 % of solid yield, 28.12 % of liquid yield and the highest hydrocarbon concentration of 19.02 %.

[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.

Consideration of the Aluminum Distribution in Zeolites in Theoretical and Experimental Catalysis Research

DOE PAGES

Knott, Brandon C.; Nimlos, Claire T.; Robichaud, David J.; ...

2017-12-11

Research efforts in zeolite catalysis have become increasingly cognizant of the diversity in structure and function resulting from the distribution of framework aluminum atoms, through emerging reports of catalytic phenomena that fall outside those recognizable as the shape-selective ones emblematic of its earlier history. Molecular-level descriptions of how active-site distributions affect catalysis are an aspirational goal articulated frequently in experimental and theoretical research, yet they are limited by imprecise knowledge of the structure and behavior of the zeolite materials under interrogation. In experimental research, higher precision can result from more reliable control of structure during synthesis and from more robustmore » and quantitative structural and kinetic characterization probes. In theoretical research, construction of models with specific aluminum locations and distributions seldom capture the heterogeneity inherent to the materials studied by experiment. In this Perspective, we discuss research findings that appropriately frame the challenges in developing more predictive synthesis-structure-function relations for zeolites, highlighting studies on ZSM-5 zeolites that are among the most structurally complex molecular sieve frameworks and the most widely studied because of their versatility in commercial applications. We discuss research directions to address these challenges and forge stronger connections between zeolite structure, composition, and active sites to catalytic function. Such connections promise to aid in bridging the findings of theoretical and experimental catalysis research, and transforming zeolite active site design from an empirical endeavor into a more predictable science founded on validated models.« less

Potassic zeolites from Brazilian coal ash for use as a fertilizer in agriculture.

PubMed

Flores, Camila Gomes; Schneider, Helena; Marcilio, Nilson Romeu; Ferret, Lizete; Oliveira, João Carlos Pinto

2017-12-01

Brazilian coal has an ash content ranging from 30 to 50% by weight. Consequently, its use in coal-fired thermoelectric for power production generates a lot of waste. The construction sector is the largest consumer of coal ash, but it cannot absorb the entire amount generated. Thus, other applications for coal ash should be studied in aim to optimize the use of this industrial waste. This research had as focus to synthesize potassic zeolite from of the coal ash into on potassium fertilizer for the grown wheat plant. In this work, it was used a subbituminous coal from Mina do Leão (RS, Brazil) presenting 48.7% ash content on a dry basis. Concerning the synthesis of potassic zeolite, it was adopted the conventional method of hydrothermal treatment with potassium hydroxide. A schedule of experiments was conducted in order to define the optimum condition of zeolite synthesis that was then used an alkaline solution of 5M KOH with a reaction time of 24h at 150°C. According to this procedure, it was obtained a zeolite with a single crystalline phase, identified through X-ray diffraction as Merlinoite. Subsequently, it was performed a set of tests using potassic zeolite asa fertilizer for plants in a greenhouse. The synthesized potassic zeolite showed a good potential for its use as fertilizer in agriculture. Copyright © 2017 Elsevier Ltd. All rights reserved.

Consideration of the Aluminum Distribution in Zeolites in Theoretical and Experimental Catalysis Research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knott, Brandon C.; Nimlos, Claire T.; Robichaud, David J.

Research efforts in zeolite catalysis have become increasingly cognizant of the diversity in structure and function resulting from the distribution of framework aluminum atoms, through emerging reports of catalytic phenomena that fall outside those recognizable as the shape-selective ones emblematic of its earlier history. Molecular-level descriptions of how active-site distributions affect catalysis are an aspirational goal articulated frequently in experimental and theoretical research, yet they are limited by imprecise knowledge of the structure and behavior of the zeolite materials under interrogation. In experimental research, higher precision can result from more reliable control of structure during synthesis and from more robustmore » and quantitative structural and kinetic characterization probes. In theoretical research, construction of models with specific aluminum locations and distributions seldom capture the heterogeneity inherent to the materials studied by experiment. In this Perspective, we discuss research findings that appropriately frame the challenges in developing more predictive synthesis-structure-function relations for zeolites, highlighting studies on ZSM-5 zeolites that are among the most structurally complex molecular sieve frameworks and the most widely studied because of their versatility in commercial applications. We discuss research directions to address these challenges and forge stronger connections between zeolite structure, composition, and active sites to catalytic function. Such connections promise to aid in bridging the findings of theoretical and experimental catalysis research, and transforming zeolite active site design from an empirical endeavor into a more predictable science founded on validated models.« less

Indocyanine green videoangiography (ICGV)-guided surgery of parasagittal meningiomas occluding the superior sagittal sinus (SSS).

PubMed

d'Avella, Elena; Volpin, Francesco; Manara, Renzo; Scienza, Renato; Della Puppa, Alessandro

2013-03-01

Maximal safe resection is the goal of correct surgical treatment of parasagittal meningiomas, and it is intimately related to the venous anatomy both near and directly involved by the tumor. Indocyanine green videoangiography (ICGV) has already been advocated as an intra-operative resourceful technique in brain tumor surgery for the identification of vessels. The aim of this study was to investigate the role of ICGV in surgery of parasagittal meningiomas occluding the superior sagittal sinus (SSS). In this study, we prospectively analyzed clinical, radiological and intra-operative findings of patients affected by parasagittal meningioma occluding the SSS, who underwent ICGV assisted-surgery. Radiological diagnosis of complete SSS occlusion was pre-operatively established in all cases. ICGV was performed before dural opening, before and during tumor resection, at the end of the procedure. Five patients were included in our study. In all cases, ICGV guided dural opening, tumor resection, and venous management. The venous collateral pathway was easily identified and preserved in all cases. Radical resection was achieved in four cases. Surgery was uneventful in all cases. Despite the small number of patients, our study shows that ICG videoangiography could play a crucial role in guiding surgery of parasagittal meningioma occluding the SSS. Further studies are needed to define the role of this technique on functional and oncological outcome of these patients.

One-Step Hydrothermal Synthesis of Zeolite X Powder from Natural Low-Grade Diatomite.

PubMed

Yao, Guangyuan; Lei, Jingjing; Zhang, Xiaoyu; Sun, Zhiming; Zheng, Shuilin

2018-05-28

Zeolite X powder was synthesized using natural low-grade diatomite as the main source of Si but only as a partial source of Al via a simple and green hydrothermal method. The microstructure and surface properties of the obtained samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), wavelength dispersive X-ray fluorescence (XRF), calcium ion exchange capacity (CEC), thermogravimetric-differential thermal (TG-DTA) analysis, and N₂ adsorption-desorption technique. The influence of various synthesis factors, including aging time and temperature, crystallization time and temperature, Na₂O/SiO₂ and H₂O/Na₂O ratio on the CEC of zeolite, were systematically investigated. The as-synthesized zeolite X with binary meso-microporous structure possessed remarkable thermal stability, high calcium ion exchange capacity of 248 mg/g and large surface area of 453 m²/g. In addition, the calcium ion exchange capacity of zeolite X was found to be mainly determined by the crystallization degree. In conclusion, the synthesized zeolite X using diatomite as a cost-effective raw material in this study has great potential for industrial application such as catalyst support and adsorbent.

Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oleksiak, Matthew D.; Ghorbanpour, Arian; Conato, Marlon T.

Designing nanoporous zeolites with tunable physicochemical properties can substantially impact their performance in commercial applications spanning diverse areas such as adsorption, separations, catalysis, and drug delivery. Zeolite synthesis typically requires the use of an organic structure-directing agent to facilitate the formation of crystals with specific pore size and topology. Attempts to remove organics from syntheses to achieve commercially-viable methods of preparing zeolites often lead to the formation of unwanted crystal polymorphs (i.e., impurities). Here, we present an organic-free synthesis of the small-pore zeolite P (GIS framework topology) that can be selectively tailored to produce two pure polymorphs: P1 and P2.more » To this end, we developed kinetic phase diagrams that identify synthesis compositions leading to the formation of GIS (P1 and P2), as well as their structural analogues MER and PHI. Using a combination of adsorption measurements and density functional theory (DFT) calculations, we also show that both GIS polymorphs are highly selective adsorbents for H2O relative to other light gases (e.g,, H2, N2, CO2). These studies highlight the potential application of GIS materials for dehydration processes, while our findings also refute prior theoretical studies postulating that GIS-type zeolites are excellent materials for CO2 separation/sequestration. Moreover, there is an impetus for discovering novel small-pore zeolites that are shape-selective catalysts for the production of value-added chemicals (e.g., light olefins); thus, our discovery of more thermally-stable P2 opens new avenues for exploring the potential role of this material as a high-performance catalyst.« less

Preliminary market analysis for large zeolite crystals. B.S. Thesis

NASA Technical Reports Server (NTRS)

Doblmaier, Thomas; Grafing, Paul; Knight, Kim

1987-01-01

Zeolite crystals are used in the manufacture of countless products today, which utilize their properties of absorption, ion exchange, and catalysis. It was determined that zeolites grown in space could be much larger in size than any of those currently available on Earth. The objective was to identify and examine some of the potential uses for these larger crystals. Of the several industries examined, the medical and nuclear industries offer the greatest potential.

Commander Bowersox Tends to Zeolite Crystal Samples Aboard Space Station

NASA Technical Reports Server (NTRS)

2003-01-01

Expedition Six Commander Ken Bowersox spins Zeolite Crystal Growth sample tubes to eliminate bubbles that could affect crystal formation in preparation of a 15 day experiment aboard the International Space Station (ISS). Zeolites are hard as rock, yet are able to absorb liquids and gases like a sponge. By using the ISS microgravity environment to grow better, larger crystals, NASA and its commercial partners hope to improve petroleum manufacturing and other processes.

Hierarchical Zeolites with Amine-Functionalized Mesoporous Domains for Carbon Dioxide Capture.

PubMed

Nguyen, Tien Hoa; Kim, Sungjune; Yoon, Minyoung; Bae, Tae-Hyun

2016-03-08

To prepare materials with high CO2 adsorption, a series of hierarchical LTA zeolites possessing various mesopore spaces that are decorated with alkylamines was designed and synthesized. The highest CO2 uptake capacity was achieved when (3-aminopropyl)trimethoxysilane (APTMS) was grafted onto the hierarchical LTA zeolite having the largest mesopores. Owing to the contributions of both alkylamine groups grafted onto the mesopore surfaces and active sites in the LTA zeolites, the amount of CO2 that can be taken up on these materials is much higher than for conventional aminosilicas such SBA-15 and MCM-41. Furthermore, the adsorbent shows good CO2 uptake capacity and recyclability in dynamic flow conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

[In vitro study of vitamins B1, B2 and B6 adsorption on zeolite].

PubMed

Basić, Zorica; Kilibarda, Vesna; Dobrić, Silva; Resanović, Radmila

2011-01-01

Zeolites are the hydratised alumosilicates of alcali and earthalcali cations, which have a long three-dimensional crystal structure. Preparations on the basis of zeolites are used for adsorption of organic and nonorganic toxic substances and they, also, find more and more use in veterinary and human medicine and pharmacy. The aim of this study was to evaluate the possibilities of zeolite to adsorb vitamins B1, B2 and B6 in acid and neutral solutions, as well as the characteristics of the process (saturability, reversibility and competitiveness). The specific and sensitive HPLC method with fluorescent detector was used for determination of vitamins B1, B2 and B6. Analyte separation and detection were carried out by applying the reverse-phase method on column C18. An in vitro experiment was done by testing the influence of pH value (2 and 7), concentration of vitamin solution (1, 2 and 5 mg/L), the length of contact with zeolite (10-180 min) and cation competitiveness on the exchange capacity, which is achieved by media and zeolite contact, as well as a possible vitamins desorption through changing pH value of the solution at 37 degrees C. Jon competitiveness was examined by adding commercial feed mixture (grower) with a defined content of the examined vitamins in zeolite solutions the pH = 2 and pH = 7. Vitamins B1, B2 and B6 were stable in both pH=2 and pH = 7 solutions at 37 degrees C, in the defined time intervals. In acid solution concentrations of vitamins significantly declined in the first 10 min, with no significant decline in further 30 min for all the three concentrations tests. In neutral solution, after the addition of 1% zeolite, decrease in vitamins concentrations was slightly lower than in acid solution, but also significant in the first 10 min of the contact with zeolite. It was found that zeolite, which adsorbed vitamins in acid solution, transferred in the neutral one released a significant quantity of adsorbed vitamins after 30 min of extraction

An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

EPA Science Inventory

Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2•6H2O functionalization of zeolite. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The adsorption capacity of the adsorbents at 21...

Adsorption and desorption of carbaryl on hexadecyl trimethyl ammonium bromide modified zeolite NaY using RGB portable photometer

NASA Astrophysics Data System (ADS)

Patdhanagul, Nopbhasinthu; Chanpaka, Saiphon; Intharaksa, Orapan; Sirival, Rujikarn; Thanomsith, Kannikar; Wongkwanklom, Sarayuth

2018-04-01

The carbaryl adsorption-desorption isotherms of zeolite NaY and hexadecyl trimethyl ammonium bromide (HTAB) modified zeolite NaY were investigated. Zeolite NaY was synthesized and modified by HTAB in the concentration range 0.1 - 10.0 mM. The adsorption isotherms indicated that zeolite modified with HTAB could significantly enhance the carbaryl adsorption capacity. Zeolite NaY modified with 5.0 mM HTAB gave great carbaryl adsorption because of hydrophilic surface. The 5.0 mM HTAB could adsorb up to 145.75 ppm g-1 of carbaryl which was equivalent to a 36.7% increase. The Surface area characterization showed the remaining of pore volume and pore size diameter and external surface area whereas the BET surface area and micropore surface area of modified zeolite slightly decreased. The XRD results indicate that modification of zeolite NaY with HTAB does not change the crystallinity of the starting zeolite. The elemental analysis indicated that the Si/Al ratio of synthesized zeolite NaY was close to 2.43. Desorption of carbaryl was tested by organic solvents such as methanol, ethanol, tetrahydrofuran, hexane and Deionized water. The results demonstrated that the percentage desorption of methanol is the highest. Carbaryl was quantitatively desorbed with percentage desorption of 82-100 %. It indicated sorption mechanism of carbaryl on the modified sorbent which was principally driven by hydrophobic forces.

Treatment of radioactive liquid waste by sorption on natural zeolite in Turkey.

PubMed

Osmanlioglu, Ahmet Erdal

2006-09-01

Liquid radioactive waste has been generated from the use of radioactive materials in industrial applications, research and medicine in Turkey. Natural zeolites (clinoptilolite) have been studied for the removal of several key radionuclides ((137)Cs, (60)Co, (90)Sr and (110m)Ag) from liquid radioactive waste. The aim of the present study is to investigate effectiveness of zeolite treatment on decontamination factor (DF) in a combined process (chemical precipitation and adsorption) at the laboratory tests and scale up to the waste treatment plant. In this study, sorption and precipitation techniques were adapted to decontamination of liquid low level waste (LLW). Effective decontamination was achieved when sorbents are used during the chemical precipitation. Natural zeolite samples were taken from different zeolite formations in Turkey. Comparison of the ion-exchange properties of zeolite minerals from different formations shows that Gordes clinoptilolite was the most suitable natural sorbent for radionuclides under dynamic treatment conditions and as an additive for chemical precipitation process. Clinoptilolite were shown to have a high selectivity for (137)Cs and (110m)Ag as sorbent. In the absence of potassium ions, native clinoptilolite removed (60)Co and (90)Sr very effectively from the liquid waste. In the end of this liquid waste treatment, decontamination factor was provided as 430 by using 0.5 mm clinoptilolite at 30 degrees C.

Zeolite inorganic scaffolds for novel biomedical application: Effect of physicochemical characteristic of zeolite membranes on cell adhesion and viability

NASA Astrophysics Data System (ADS)

Tavolaro, Palmira; Catalano, Silvia; Martino, Guglielmo; Tavolaro, Adalgisa

2016-09-01

The design, preparation and selection of inorganic materials useful as functional scaffolds for cell adhesion is a complex question based both on the understanding of the chemical behavior of the materials and individual cells, and on their interactions. Pure zeolite membranes formed from synthetic crystals offer chemically-capable being modulated silanolic surfaces that are amenable to adhesion and growth of fibroblasts. We report the facile preparation of reusable, very longlasting, biocompatible, easily sterilized synthetic scaffolds in a zeolite membrane configuration, which are very stable in aqueous media (apart from ionic strength and pH values), able to adsorb pollutant species and to confine undesired toxic ions (present in culture media). This may ultimately lead to the development of cell supports for economic antibiotic-free culture media.

Influence of zeolite precipitation on borosilicate glass alteration under hyperalkaline conditions

NASA Astrophysics Data System (ADS)

Mercado-Depierre, S.; Fournier, M.; Gin, S.; Angeli, F.

2017-08-01

This study enables a better understanding of how nucleation-growth of zeolites affects glass dissolution kinetics in hyperalkaline solutions characteristic of cement waters. A 20-oxide borosilicate glass, an inactive surrogate of a typical intermediate level waste glass, was altered in static mode at 50 °C in a hyperalkaline solution rich in Na+, K+ and Ca2+ and at an initial pH50°C of 12.6. Experiments were performed at four glass-surface-area-to-solution-volume (S/V) ratios to investigate various reaction progresses. Two types of glass alteration kinetics were obtained: (i) at low S/V, a sharp alteration resumption occurred after a rate drop regime, (ii) at high S/V, a high dissolution rate was maintained throughout the test duration with a slight progressive slow-down. In all the experiments, zeolites precipitated but the time taken to form stable zeolite nuclei varied dramatically depending on the S/V. Resulting changes in pH affected zeolite composition, morphology, solubility and growth rate. A change in a critical parameter such as S/V affected all the processes controlling glass dissolution.

CR-100 synthetic zeolite adsorption characteristics toward Northern Banat groundwater ammonia.

PubMed

Tomić, Željko; Kukučka, Miroslav; Stojanović, Nikoleta Kukučka; Kukučka, Andrej; Jokić, Aleksandar

2016-10-14

The adsorption characteristics of synthetic zeolite CR-100 in a fixed-bed system using continuous flow of groundwater containing elevated ammonia concentration were examined. The possibilities for adsorbent mass calculation throughout mass transfer zone using novel mathematical approach as well as zeolite adsorption capacity at every sampling point in time or effluent volume were determined. The investigated adsorption process consisted of three clearly separated steps indicated to sorption kinetics. The first step was characterized by decrease and small changes in effluent ammonia concentration vs. experiment time and quantity of adsorbed ammonia per mass unit of zeolite. The consequences of this phenomenon were showed in the plots of the Freundlich and the Langmuir isotherm models through a better linear correlation according as graphical points contingent to the first step were not accounted. The Temkin and the Dubinin-Radushkevich isotherm models showed the opposite tendency with better fitting for overall measurements. According to the obtained isotherms parameter data, the investigated process was found to be multilayer physicochemical adsorption, and also that synthetic zeolite CR-100 is a promising material for removal of ammonia from Northern Banat groundwater with an ammonia removal efficiency of 90%.

High ion-exchange properties of hybrid materials from X-type zeolite and ground glass powder

NASA Astrophysics Data System (ADS)

Taira, Nobuyuki; Yoshida, Kohei

2017-10-01

Zeolites are crystalline aluminosilicates with a homogeneous distribution of micropores with a superior cation-exchange capacity. Because they have especially excellent selective exchange properties, a considerable number of studies have been conducted on treating water containing radioisotopes using the zeolites. When using artificial zeolites, they have inferior sinterability; in addition, it is quite hard for them to remove from polluted liquid since these artificial zeolites are principally synthesized as a form of powder, which is a disadvantage. In this study, hybrid materials were prepared from X-type zeolite and waste glass powder. Their ion-removal effect and mechanical strength were investigated. The zeolite and waste glass were ground in an agate mortar in several ratios. 0.5 g of the mixture was pressure-molded into pellets having a diameter of 7 mm. These pellets were slowly heated at the speed of 240°C/h to 700°C and maintained at 700°C for 2 h. The removal rate of Sr2+ ions increased as the amount of X-type zeolite in the hybrid materials increased; the former increased up to 100% when the content of latter exceeded 50%. The mechanical strength increased by increasing the amount of glass in the hybrid materials. This is attributed to the fact that the glass powder acts as a binder that improves the densification and consequently the mechanical strength of the hybrid materials.

Influence of Zeolite on fatty acid composition and egg quality in Tunisian Laying Hens

PubMed Central

2012-01-01

Background The health benefits of omega-3 and omega-6 polyunsaturated fatty acids (PUFA) are generally recognized. Unfortunately, in most Mediterranean countries, the recommended daily intake of these compounds is rarely met. Therefore, enrichment of commonly occurring foods can boost intake of these fatty acids. In this regard, eggs are an interesting target, as they form an integral part of the diet. Result Zeolite (Clinoptilolites) was added to Laying Hens feed at concentrations 1% or 2% and was evaluated for its effects on performance of the production and on egg quality. The Laying Hens were given access to 110 g of feed mixtures daily that was either a basal diet or a ‘zeolite diet’ (the basal diet supplemented with clinoptilolite at a level of 1% or 2%). It was found that zeolite treatment had a positive and significatif (p < 0.05) effect on some parameters that were measured like egg height and eggshell strength. While dietary zeolite supplementation tended to/or has no significant effects on total egg, eggshell, yolk and albumen weights. It was found also that zeolite mainly increases level of polyunsaturated fatty acids in egg. Conclusion This study showed the significance of using zeolite, as a feed additive for Laying Hens, as part of a comprehensive program to control egg quality and to increase level of polyunsaturated fatty acids on egg. PMID:22676421