Inhibition of microbial concrete corrosion by Acidithiobacillus thiooxidans with functionalised zeolite-A coating.

PubMed

Haile, Tesfaalem; Nakhla, George

2009-01-01

The inhibition of the corrosive action of Acidithiobacillus thiooxidans on concrete specimens coated by functionalised zeolite-A containing 14% zinc and 5% silver by weight was studied. Uncoated concrete specimens, epoxy-coated concrete specimens (EP), and functionalised zeolite-A coated concrete specimens with epoxy to zeolite weight ratios of 3:1 (Z1), 2:2 (Z2) and 1:3 (Z3) were studied. Specimens were characterised by x-ray powder diffraction and field emission scanning electron microscopy for the identification of corrosion products and morphological changes. Biomass growth at the conclusion of the 32-day experiments was 4, 179 and 193 mg volatile suspended solids g(-1) sulphur for the uncoated, EP and Z1 specimens, whereas that of Z2 and Z3 were negligible. In the uncoated, EP and Z1 specimens, sulphate production rates were 0.83, 9.1 and 8.8 mM SO(4)(2-) day(-1) and the specific growth rates, mu, were 0.14, 0.57 and 0.47 day(-1), respectively. The corresponding values for Z2 and Z3 were negligible due to their bacterial inhibition characteristics.

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

PubMed

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

2016-01-01

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

Intracellular delivery of peptide nucleic acid and organic molecules using zeolite-L nanocrystals.

PubMed

Bertucci, Alessandro; Lülf, Henning; Septiadi, Dedy; Manicardi, Alex; Corradini, Roberto; De Cola, Luisa

2014-11-01

The design and synthesis of smart nanomaterials can provide interesting potential applications for biomedical purposes from bioimaging to drug delivery. Manufacturing multifunctional systems in a way to carry bioactive molecules, like peptide nucleic acids able to recognize specific targets in living cells, represents an achievement towards the development of highly selective tools for both diagnosis and therapeutics. This work describes a very first example of the use of zeolite nanocrystals as multifunctional nanocarriers to deliver simultaneously PNA and organic molecules into living cells. Zeolite-L nanocrystals are functionalized by covalently attaching the PNA probes onto the surface, while the channel system is filled with fluorescent guest molecules. The cellular uptake of the PNA/Zeolite-L hybrid material is then significantly increased by coating the whole system with a thin layer of biodegradable poly-L-lysine. The delivery of DAPI as a model drug molecule, inserted into the zeolite pores, is also demonstrated to occur in the cells, proving the multifunctional ability of the system. Using this zeolite nanosystem carrying PNA probes designed to target specific RNA sequences of interest in living cells could open new possibilities for theranostic and gene therapy applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and performance of manganese-oxide-coated zeolite for the removal of manganese-contamination in groundwater.

PubMed

Lyu, Cong; Yang, Xuejiao; Zhang, Shengyu; Zhang, Qihui; Su, Xiaosi

2017-12-29

A promising and easily prepared catalytic filler media, manganese-oxide-coated zeolite (MOCZ), for the removal of Mn (II) contamination in groundwater was studied. The optimal condition for MOCZ preparation was given as follows: acid activation of zeolite with 5% HCl mass percent for 12 h, then soaking of acid-activated zeolite with 7% KMnO 4 mass percent for 8 h, and finally calcination at 300°C for 5 h. Acid activation significantly enlarged the specific surface area of the zeolite (>79 m 2  g -1 ), subsequently enhancing the coating of manganese oxides onto the surface of the zeolite. This was further supported by the manganese-to-zeolite ratio (γ Mn ) and Energy dispersive analysis-mapping. The γ Mn was over 12.26 mg Mn g -1 zeolite, representing more active sites for the adsorption and catalytic-oxidation of Mn (II). As such, great performance of Mn (II) removal by MOCZ was obtained in the filter experiment. An estimated 98-100% removal efficiency of Mn (II) was achieved in a greatly short startup time (only 2 h). During the filtration process, newborn flocculent manganese oxides with a mixed-valence of manganese (Mn (II) and Mn (IV)) were generated on the MOCZ surface, further facilitating the adsorption and catalytic-oxidation of Mn (II). The filter with MOCZ as adsorbent had a great performance on the Mn (II) removal in a wide range of hydraulic retention time (HRT) (4-40 min), particularly in a short HRT. Besides, the filter prolonged the filtration period (60 days), which would significantly reduce the frequency of backwash. Thus, it could be concluded that MOCZ prepared in this study showed a good performance in terms of Mn (II) removal in waterworks, especially small waterworks in the villages/towns.

Molecular Adsorber Coating

NASA Technical Reports Server (NTRS)

Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

2011-01-01

A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

Silver zeolite antimicrobial activity in aluminium heating, ventilation and air conditioning system ducts.

PubMed

Rizzetto, R; Mansi, A; Panatto, D; Rizzitelli, E; Tinteri, C; Sasso, T; Gasparini, R; Crovari, P

2008-03-01

Air pollution in confined environments is a serious health problem, in that most people spend long periods indoors (in homes, offices, classrooms etc.). Some people (children, the elderly, heart disease patients, asthmatic or allergic subjects) are at greater risk because of their conditions of frailty. The growing use of air-conditioning systems in many public and private buildings aggravates this health risk, especially when these systems are not correctly installed or regularly serviced. The aim of our study was to verify the capacity of Ag+ ions to stop the growth of bacteria and moulds inside the ducts of Heating, Ventilation and Air Conditioning system ducts (HVAC) systems when these ducts were lined with active Ag+ ions zeolite-coated panels. A Y-shaped HVAC model with two branches was used; one branch was made of traditional galvanized iron, as was the whole system, while the other was lined with active Ag+ zeolite-coated polyurethane panels. During the test, samples of dust present inside both ducts were collected and seeded in liquid and solid media to detect bacteria and moulds. The presence of bacteria was also sought in the air emerging from the outlets of both ducts. Tests made on samples of particulate collected from the two different ducts revealed a lower total bacterial load in the samples collected from the Ag+ zeolite-coated duct than in the samples from the traditional Zn galvanized duct. In addition, the values of bacterial load found in the air emerging from the Ag+ ions zeolite-lined duct were 5 times lower than those found in the air from the traditional galvanized iron duct. The utilization of Ag+ zeolite-coated panels in air-conditioning systems could improve the quality of the emerging air in comparison with traditional installations in galvanized iron. This innovation could prove particularly advantageous in the event of accidents during the installation of air-conditioning systems or of contaminated aerosols coming from outside.

Novel Synthesis Method of Micronized Ti-Zeolite Na-A and Cytotoxic Activity of Its Silver Exchanged Form

PubMed Central

Youssef, H. F.; Hegazy, W. H.; Abo-almaged, H. H.; El-Bassyouni, G. T.

2015-01-01

The core-shell method is used as a novel synthetic process of micronized Ti-Zeolite Na-A which involves calcination at 700°C of coated Egyptian Kaolin with titanium tetrachloride in acidic medium as the first step. The produced Ti-coated metakaolinite is subjected to microwave irradiation at low temperature of 80°C for 2 h. The prepared micronized Ti-containing Zeolites-A (Ti-Z-A) is characterized by FTIR, XRF, XRD, SEM, and EDS elemental analysis. Ag-exchanged form of Ti-Z-Ag is also prepared and characterized. The Wt% of silver exchanged onto the Ti-Zeolite structure was determined by atomic absorption spectra. The in vitro cytotoxic activity of Ti-Z-Ag against human hepatocellular carcinoma cell line (HePG2), colon cell line carcinoma (HCT116), lung carcinoma cell line (A549), and human Caucasian breast adenocarcinoma (MCF7) is reported. The results were promising and revealed that the exchanged Ag form of micronized Ti-Zeolite-A can be used as novel antitumor drug. PMID:25705142

Improving the osteointegration of Ti6Al4V by zeolite MFI coating

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

Li, Yong; Jiao, Yilai; Li, Xiaokang

Osteointegration is crucial for success in orthopedic implantation. In recent decades, there have been numerous studies aiming to modify titanium alloys, which are the most widely used materials in orthopedics. Zeolites are solid aluminosilicates whose application in the biomedical field has recently been explored. To this end, MFI zeolites have been developed as titanium alloy coatings and tested in vitro. Nevertheless, the effect of the MFI coating of biomaterials in vivo has not yet been addressed. The aim of the present work is to evaluate the effects of MFI-coated Ti6Al4V implants in vitro and in vivo. After surface modification, the surface was investigated usingmore » field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). No difference was observed regarding the proliferation of MC3T3-E1 cells on the Ti6Al4V (Ti) and MFI-coated Ti6Al4V (M−Ti) (p > 0.05). However, the attachment of MC3T3-E1 cells was found to be better in the M−Ti group. Additionally, ALP staining and activity assays and quantitative real-time RT-PCR indicated that MC3T3-E1 cells grown on the M−Ti displayed high levels of osteogenic differentiation markers. Moreover, Van-Gieson staining of histological sections demonstrated that the MFI coating on Ti6Al4V scaffolds significantly enhanced osteointegration and promoted bone regeneration after implantation in rabbit femoral condylar defects at 4 and 12 weeks. Therefore, this study provides a method for modifying Ti6Al4V to achieve improved osteointegration and osteogenesis. - Highlights: • Osteointegration is a crucial factor for orthopedic implants. • We coated MFI zeolite on Ti6Al4V substrates and investigated the effects in vitro and in vivo. • The MFI coating displayed good biocompatibility and promoted osteogenic differentiation in vitro. • The MFI coating promoted osteointegration and osteogenesis peri-implant in vivo.« less

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.

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.

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.

Sub-Micrometer Zeolite Films on Gold-Coated Silicon Wafers with Single-Crystal-Like Dielectric Constant and Elastic Modulus

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

Tiriolo, Raffaele; Rangnekar, Neel; Zhang, Han

A low-temperature synthesis coupled with mild activation produces zeolite films exhibiting low dielectric constant (low-k) matching the theoretically predicted and experimentally measured values for single crystals. This synthesis and activation method allows for the fabrication of a device consisting of a b-oriented film of the pure-silica zeolite MFI (silicalite-1) supported on a gold-coated silicon wafer. The zeolite seeds are assembled by a manual assembly process and subjected to optimized secondary growth conditions that do not cause corrosion of the gold underlayer, while strongly promoting in-plane growth. The traditional calcination process is replaced with a non-thermal photochemical activation to ensure preservationmore » of an intact gold layer. The dielectric constant (k), obtained through measurement of electrical capacitance in a metal-insulator-metal configuration, highlights the ultralow k approximate to 1.7 of the synthetized films, which is among the lowest values reported for an MFI film. There is large improvement in elastic modulus of the film (E approximate to 54 GPa) over previous reports, potentially allowing for integration into silicon wafer processing technology.« less

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.

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.

Development of the Molecular Adsorber Coating for Spacecraft and Instrument Interiors

NASA Technical Reports Server (NTRS)

Abraham, Nithin

2011-01-01

On-orbit Molecular Contamination occurs when materials outgas and deposit onto very sensitive interior surfaces of the spacecraft and instruments. The current solution, Molecular Adsorber Pucks, has disadvantages, which are reviewed. A new innovative solution, Molecular Adsorber Coating (MAC), is currently being formulated, optimized, and tested. It is a sprayable alternative composed of Zeolite-based coating with adsorbing properties.

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.

Capture and isotopic exchange method for water and hydrogen isotopes on zeolite catalysts up to technical scale for pre-study of processing highly tritiated water

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

Michling, R.; Braun, A.; Cristescu, I.

2015-03-15

Highly tritiated water (HTW) may be generated at ITER by various processes and, due to the excessive radio toxicity, the self-radiolysis and the exceedingly corrosive property of HTW, a potential hazard is associated with its storage and process. Therefore, the capture and exchange method for HTW utilizing Molecular Sieve Beds (MSB) was investigated in view of adsorption capacity, isotopic exchange performance and process parameters. For the MSB, different types of zeolite were selected. All zeolite materials were additionally coated with platinum. The following work comprised the selection of the most efficient zeolite candidate based on detailed parametric studies during themore » H{sub 2}/D{sub 2}O laboratory scale exchange experiments (about 25 g zeolite per bed) at the Tritium Laboratory Karlsruhe (TLK). For the zeolite, characterization analytical techniques such as Infrared Spectroscopy, Thermogravimetry and online mass spectrometry were implemented. Followed by further investigation of the selected zeolite catalyst under full technical operation, a MSB (about 22 kg zeolite) was processed with hydrogen flow rates up to 60 mol*h{sup -1} and deuterated water loads up to 1.6 kg in view of later ITER processing of arising HTW. (authors)« less

Removing Escherichia coli from water using zinc oxide-coated zeolite.

PubMed

Wang, Lingling; Wu, Wenlin; Xie, Xiaolan; Chen, Hongbin; Lin, Jianming; Dionysiou, Dionysios D

2018-05-11

The removal of Escherichia coli (E. coli) from water by zinc oxide-coated zeolite (ZOCZ) and ZOCZ's antibacterial properties were examined in laboratory experiments using plate counting method and tests of cell apoptosis. Batch experiments showed that ZOCZ has a maximum removal capacity for E. coli of about 4.34 × 10 6  CFU g -1  at 25 °C. Element mappings confirm that zinc ions accumulate in the E. coli cells causing cell death. Pseudo-second-order kinetics and Freundlich isotherms were found to best describe the removal of E. coli, suggesting that a multilayer of E. coli cells forms on the surface of ZOCZ particles. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sorption of Cu(II) Ions on Chitosan-Zeolite X Composites: Impact of Gelling and Drying Conditions.

PubMed

Djelad, Amal; Morsli, Amine; Robitzer, Mike; Bengueddach, Abdelkader; di Renzo, Francesco; Quignard, Françoise

2016-01-19

Chitosan-zeolite Na-X composite beads with open porosity and different zeolite contents were prepared by an encapsulation method. Preparation conditions had to be optimised in order to stabilize the zeolite network during the polysaccharide gelling process. Composites and pure reference components were characterized using X-ray diffraction (XRD); scanning electron microscopy (SEM); N₂ adsorption-desorption; and thermogravimetric analysis (TG). Cu(II) sorption was investigated at pH 6. The choice of drying method used for the storage of the adsorbent severely affects the textural properties of the composite and the copper sorption effectiveness. The copper sorption capacity of chitosan hydrogel is about 190 mg·g(-1). More than 70% of this capacity is retained when the polysaccharide is stored as an aerogel after supercrititcal CO₂ drying, but nearly 90% of the capacity is lost after evaporative drying to a xerogel. Textural data and Cu(II) sorption data indicate that the properties of the zeolite-polysaccharide composites are not just the sum of the properties of the individual components. Whereas a chitosan coating impairs the accessibility of the microporosity of the zeolite; the presence of the zeolite improves the stability of the dispersion of chitosan upon supercritical drying and increases the affinity of the composites for Cu(II) cations. Chitosan-zeolite aerogels present Cu(II) sorption properties.

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, e.g. erionite. However, in other zeolites, the antiproliferative and pro-apoptotic effects can be used for tumor therapy.

Incredible antibacterial activity of noble metal functionalized magnetic core-zeolitic shell nanostructures.

PubMed

Padervand, M; Janatrostami, S; Karanji, A Kiani; Gholami, M R

2014-02-01

Functionalized magnetic core-zeolitic shell nanostructures were prepared by hydrothermal and coprecipitation methods. The products were characterized by Vibrating Sample Magnetometer (VSM), X-ray powder diffraction (XRD), Fourier Transform Infrared (FTIR) spectra, nitrogen adsorption-desorption isotherms, and Transmission Electron Microscopy (TEM). The growth of mordenite nanoparticles on the surface of silica coated nickel ferrite nanoparticles in the presence of organic templates was also confirmed. Antibacterial activity of the prepared nanostructures was investigated by the inactivation of Escherichia coli as a gram negative bacterium. A new mechanism was proposed for inactivation of E. coli over the prepared samples. In addition, the Minimum Inhibitory Concentration (MIC) and reuse ability were studied. TEM images of the destroyed cell wall after the treatment time were performed to illustrate the inactivation mechanism. According to the experimental results, the core-shell nanostructures which were modified by organic agents and then functionalized with noble metal nanoparticles were the most active. The interaction of the noble metals with the organic components on the surface of nanostructures was studied theoretically and the obtained results were used to interpret the experimental results. © 2013. Published by Elsevier B.V. All rights reserved.

Lotus Dust Mitigation Coating and Molecular Adsorber Coating

NASA Technical Reports Server (NTRS)

O'Connor, Kenneth M.; Abraham, Nithin S.

2015-01-01

NASA Goddard Space Flight Center has developed two unique coating formulations that will keep surfaces clean and sanitary and contain contaminants.The Lotus Dust Mitigation Coating, modeled after the self-cleaning, water-repellant lotus leaf, disallows buildup of dust, dirt, water, and more on surfaces. This coating, has been successfully tested on painted, aluminum, glass, silica, and some composite surfaces, could aid in keeping medical assets clean.The Molecular Adsorber Coating is a zeolite-based, sprayable molecular adsorber coating, designed to prevent outgassing in materials in vacuums. The coating works well to adsorb volatiles and contaminates in manufacturing and processing, such as in pharmaceutical production. The addition of a biocide would also aid in controlling bacteria levels.

Ultra-selective high-flux membranes from directly synthesized zeolite nanosheets

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

Jeon, Mi Young; Kim, Donghun; Kumar, Prashant

A zeolite with structure type MFI is an aluminosilicate or silicate material that has a three-dimensionally connected pore network, which enables molecular recognition in the size range 0.5-0.6 nm. These micropore dimensions are relevant for many valuable chemical intermediates, and therefore MFI-type zeolites are widely used in the chemical industry as selective catalysts or adsorbents. As with all zeolites, strategies to tailor them for specific applications include controlling their crystal size and shape. Nanometre-thick MFI crystals (nanosheets) have been introduced in pillared and self-pillared (intergrown) architectures, offering improved mass-transfer characteristics for certain adsorption and catalysis applications. Moreover, single (non-intergrown andmore » nonlayered) nanosheets have been used to prepare thin membranes that could be used to improve the energy efficiency of separation processes. However, until now, single MFI nanosheets have been prepared using a multi-step approach based on the exfoliation of layered MFI9,15, followed by centrifugation to remove non-exfoliated particles. This top-down method is time-consuming, costly and low-yield and it produces fragmented nanosheets with submicrometre lateral dimensions. Alternatively, direct (bottom-up) synthesis could produce high-aspect-ratio zeolite nanosheets, with improved yield and at lower cost. Here we use a nanocrystal-seeded growth method triggered by a single rotational intergrowth to synthesize high-aspect-ratio MFI nanosheets with a thickness of 5 nanometres (2.5 unit cells). These high-aspect-ratio nanosheets allow the fabrication of thin and defect-free coatings that effectively cover porous substrates. Finally, these coatings can be intergrown to produce high-flux and ultra-selective MFI membranes that compare favourably with other MFI membranes prepared from existing MFI materials (such as exfoliated nanosheets or nanocrystals).« less

Ultra-selective high-flux membranes from directly synthesized zeolite nanosheets

DOE PAGES

Jeon, Mi Young; Kim, Donghun; Kumar, Prashant; ...

2017-03-15

A zeolite with structure type MFI is an aluminosilicate or silicate material that has a three-dimensionally connected pore network, which enables molecular recognition in the size range 0.5-0.6 nm. These micropore dimensions are relevant for many valuable chemical intermediates, and therefore MFI-type zeolites are widely used in the chemical industry as selective catalysts or adsorbents. As with all zeolites, strategies to tailor them for specific applications include controlling their crystal size and shape. Nanometre-thick MFI crystals (nanosheets) have been introduced in pillared and self-pillared (intergrown) architectures, offering improved mass-transfer characteristics for certain adsorption and catalysis applications. Moreover, single (non-intergrown andmore » nonlayered) nanosheets have been used to prepare thin membranes that could be used to improve the energy efficiency of separation processes. However, until now, single MFI nanosheets have been prepared using a multi-step approach based on the exfoliation of layered MFI9,15, followed by centrifugation to remove non-exfoliated particles. This top-down method is time-consuming, costly and low-yield and it produces fragmented nanosheets with submicrometre lateral dimensions. Alternatively, direct (bottom-up) synthesis could produce high-aspect-ratio zeolite nanosheets, with improved yield and at lower cost. Here we use a nanocrystal-seeded growth method triggered by a single rotational intergrowth to synthesize high-aspect-ratio MFI nanosheets with a thickness of 5 nanometres (2.5 unit cells). These high-aspect-ratio nanosheets allow the fabrication of thin and defect-free coatings that effectively cover porous substrates. Finally, these coatings can be intergrown to produce high-flux and ultra-selective MFI membranes that compare favourably with other MFI membranes prepared from existing MFI materials (such as exfoliated nanosheets or nanocrystals).« less

One-pot synthesis of zeolitic imidazolate framework-8/poly (methyl methacrylate-ethyleneglycol dimethacrylate) monolith coating for stir bar sorptive extraction of phytohormones from fruit samples followed by high performance liquid chromatography-ultraviolet detection.

PubMed

You, Linna; He, Man; Chen, Beibei; Hu, Bin

2017-11-17

In this work, zeolitic imidazolate framework-8 (ZIF-8)/poly (methyl methacrylate-ethyleneglycol dimethacrylate) (MMA-EGDMA) composite monolith was in situ synthesized on stir bar by one-pot polymerization. Compared with the neat monolith, ZIF-8/poly(MMA-EGDMA) composite monolith has larger surface area and pore volume. It also exhibits higher extraction efficiency for target phytohormones than poly(MMA-EGDMA) monolith and commercial polyethylene glycol (PEG) coated stir bar. Based on it, a method of ZIF-8/poly(MMA-EGDMA) monolith coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detection (HPLC-UV) was established for the analysis of five phytohormones in apple and pear samples. The developed method exhibited low limits of detection (0.11-0.51μg/L), wide linear range (0.5-500μg/L) and good recoveries (82.7-111%), which demonstrated good application potential of the ZIF-8/monolith coated stir bar in trace analysis of organic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

High Water Tolerance of a Core-Shell-Structured Zeolite for CO2 Adsorptive Separation under Wet Conditions.

PubMed

Miyamoto, Manabu; Ono, Shumpei; Kusukami, Kodai; Oumi, Yasunori; Uemiya, Shigeyuki

2018-06-11

Dehumidification in CO 2 adsorptive separation processes is an important issue, owing to its high energy consumption. However, available adsorbents such as low-silica zeolites show a significant decrease in CO 2 adsorption capacity when water vapor is present. A core-shell-structured MFI-type zeolite with a hydrophilic ZSM-5 coated with a hydrophobic silicalite-1 shell layer was applied in CO 2 adsorptive separation under wet conditions. This hybrid material demonstrated remarkably high water tolerance with stable CO 2 adsorption performance without additional thermal treatment for regeneration, whereas a significant decrease in the CO 2 adsorption amount because of water vapor was observed on the parent ZSM-5. The core-shell structure of zeolites with high pore volumes, such as LTA or CHA, could also be suitable candidates for high CO 2 adsorption capacity and high water tolerance for practical applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Studies of the water adsorption on Lampung’s natural zeolite of Indonesia for cooling application

NASA Astrophysics Data System (ADS)

Wulandari, D. A.; Nasruddin; Lemington

2018-03-01

Part of minerals that originally formed from volcanic rock and ash layers reacting further with alkaline groundwater is called natural zeolite, where its sources are not always available in all countries. Indonesia is located in the ring of fire which have a huge sources of zeolite, one of the area is Lampung, South Sumatra. Natural zeolite has been considered as one of potential heat adsorbent medium which can contribute to the energy consumption and reduce air pollution in the using of cooling application. The characteristic of this Lampung natural zeolite such as adsorption kinetics, adsorption water uptake, and adsorption capacity were test with ASAP 2020 system. Sorption kinetics by this experiment of zeolite samples were carried out in a constant temperature and humidity chamber. The chamber can supply constant air condition with deviations of ±0.5 °C for temperature and ±3% for relative humidity. The data based on rate of adsorption and the defined working condition was set as 20°C and 70% RH. Pore volume is a significant parameter for determining the limitation of water uptake, which can describe the saturated condition of zeolite. Sorption isotherm models used to describe sorption phenomena are commonly deduced from the Polanyi potential theory were investigated. The water adsorption quantity increased with the increase of relative pressure. To sum up, this pure zeolite has a less heat and mass transfer performance so its need to be activated before using in cooling application to get their great potential and by being coated in a desiccant heat exchanger systems.

Enrichment process of biogas using simultaneous Absorption - Adsorption methods

NASA Astrophysics Data System (ADS)

Kusrini, Eny; Lukita, Maya; Gozan, Misri; Susanto, Bambang Heru; Nasution, Dedy Alharis; Rahman, Arif; Gunawan, Cindy

2017-03-01

Removal of CO2 in biogas is an essential methods to the purification and upgrading of biogas. Natural Clinoptilolite zeolites were evaluated as sorbents for purification of biogas that produced from palm oil mill effluent (POME) by anerobic-digestion method. The absorption and adsorption experiments were conducted in a fixed-bed two column adsorption unit by simultaneous absorption-adsorption method. The Ca(OH)2 solution with concentration of 0.062 M was used as absorption method. Sorbent for removal of CO2 in biogas have been prepared by modifying of Clinoptilolite zeolites with an acid (HCl, 2M) and alkaline (NaOH, 2M), calcined at 450°C and then coated using chitosan (0.5 w/v%) in order to increase their adsorption capacity. The removal of CO2 in biogas was achieved about ˜83% using 2.5 g of sorbent zeolite (2M)/chitosan dosage for each column, breakthrough time of 30 min, and flow rate of 100 mL/min. Clinoptilolite zeolites with modifications of an acid-alkaline and chitosan (zeolite (2M)/chitosan) are promising sorbents due to the amine groups from chitosan and high surface-volume ratio are one of important factors in a simultaneous absorption-adsorption method.

Zeolitic imidazolate framework-coated acoustic sensors for room temperature detection of carbon dioxide and methane

DOE PAGES

Devkota, Jagannath; Kim, Ki-Joong; Ohodnicki, Paul R.; ...

2018-01-01

The integration of nanoporous materials such as metal organic frameworks (MOFs) with sensitive transducers can result in robust sensing platforms for monitoring gases and chemical vapors for a range of applications.

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.

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.

CORROSION RESISTANT ZEOLITE COATINGS BY IN-SITU CRYSTALLIZATION. (R828134)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Zeolite Coating System for Corrosion Control to Eliminate Hexavalent Chromium from DoD Applications

DTIC Science & Technology

2009-08-01

Beving D.; Munoz R.; Yushan Y. 2005, Hydrothermal Synthesis and Corrosion Resistance of Vanadium ZSM-5 Films, The American Institute of Chemical...Engineers National Meeting, October 30 - November 4, Cincinnati, Ohio. 8) Mao Y.; Beving D.; Munoz R.; Yushan Y. 2005, Hydrothermal Synthesis of...directly at the solid-liquid interface from a synthesis solution during the coating formation process (Figure 2-4)12. The synthesis solution used is a

Study on the strategies of waste solvent minimization in automobile production industry

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

Chang, C.T.; Lin, K.L.; Wu, Y.P.

1998-12-31

There are six automobile manufacturers who produce several kinds of vehicles in Taiwan. To meet the consumer`s needs, the automobile coating processes are necessary for the basic functions of anti-rust protection, weatherproofing and appearance. Some kinds of solvents are added as thinners and additives to avoid excessive viscosity of the coating materials and to increase facility productivity. The total consumption of volatile organic solvents is about 407,000 ton/year of which about 100,700 ton/year is used in surface coating. It is worthy of attention that solvents used in automobile industries account for 7,200 ton/year in major coating processes, including electrodeposition coating,more » primer coating, top coating, and bar coating, according to statistics of VOCs emission rate calculated from the data of consumption provided by each automobile plant. The amount of solvents used for washing spray gun and base coating are about 3,350 ton/year; and about 1,700 ton/year for primer coat and clear coat. The species of organic solvents include toluene, xylene, ethylacetate, n-butyl acetate, ketone, etc. VOCs emission factor from each plant lies between 500 to 650 g-VOCs/L coating. To reduce the amount of coating and waste liquor, the suggested methods include increasing gun spray efficiency, lengthening same colors painting period, reducing the solvent content in paint, and adding treatment equipment. The high solid content painting, waterborne coat, and powder coat should be used for traditional painting. Additionally, a carbon adsorption bed and zeolite rotator recovery system can replace scrubbers since they can be used as solvent recovery equipment.« less

Sustained release of doxorubicin from zeolite-magnetite nanocomposites prepared by mechanical activation.

PubMed

Arruebo, Manuel; Fernández-Pacheco, Rodrigo; Irusta, Silvia; Arbiol, Jordi; Ibarra, M Ricardo; Santamaría, Jesús

2006-08-28

Nanocomposites consisting of magnetite and FAU zeolite with a high surface area and adsorption capacity have been prepared by mechanical activation using high-energy milling at room temperature. FTIR results, as well as HRTEM, EFTEM, and XPS measurements, show that the resulting magnetic nanoparticles are covered by a thin aluminosilicate coating. A saturation magnetization as high as 16 emu g(-1) and 94.2 Oe of coercivity were observed for the obtained composites. The main advantages of this synthesis procedure are (i) simplicity of the preparation procedure, (ii) prevention of agglomeration of the magnetite nanoparticles to a large extent, and (iii) absence of free magnetite outside the zeolitic matrix. In addition, in vitro experiments revealed that the nanoparticles prepared were able to store and release substantial amounts of doxorubicin. In view of these advantages, these magnetic nanoparticles can be considered as potential candidates for drug-delivery applications.

Sustained release of doxorubicin from zeolite magnetite nanocomposites prepared by mechanical activation

NASA Astrophysics Data System (ADS)

Arruebo, Manuel; Fernández-Pacheco, Rodrigo; Irusta, Silvia; Arbiol, Jordi; Ibarra, M. Ricardo; Santamaría, Jesús

2006-08-01

Nanocomposites consisting of magnetite and FAU zeolite with a high surface area and adsorption capacity have been prepared by mechanical activation using high-energy milling at room temperature. FTIR results, as well as HRTEM, EFTEM, and XPS measurements, show that the resulting magnetic nanoparticles are covered by a thin aluminosilicate coating. A saturation magnetization as high as 16 emu g-1 and 94.2 Oe of coercivity were observed for the obtained composites. The main advantages of this synthesis procedure are (i) simplicity of the preparation procedure, (ii) prevention of agglomeration of the magnetite nanoparticles to a large extent, and (iii) absence of free magnetite outside the zeolitic matrix. In addition, in vitro experiments revealed that the nanoparticles prepared were able to store and release substantial amounts of doxorubicin. In view of these advantages, these magnetic nanoparticles can be considered as potential candidates for drug-delivery applications.

Surfactant-Modified Soil Amendments Reduce Nitrogen and Phosphorus Leaching in a Sand-Based Rootzone.

PubMed

Shaddox, Travis W; Kruse, Jason K; Miller, Grady L; Nkedi-Kizza, Peter; Sartain, Jerry B

2016-09-01

United States Golf Association putting greens are susceptible to nitrogen (N) and phosphorus (P) leaching. Inorganic soil amendments are used to increase moisture and nutrient retention and may influence N and P leaching. This study was conducted to determine whether N and P leaching could be reduced using soil amendments and surfactant-modified soil amendments. Treatments included a control (sand), sand-peat, zeolite, calcined clay, hexadecyltrimethylammonium-zeolite, and hexadecyltrimethylammonium-calcined clay. Lysimeters were filled with a 30-cm rootzone layer of sand-peat (85:15 by volume), below which a 5-cm treatment layer of amendments was placed. A solution of NO-N, NH-N, and orthophosphate-P (2300, 2480, and 4400 μg mL, respectively) was injected at the top of each lysimeter, and leachate was collected using an autocollector set to collect a 10-mL sample every min until four pore volumes were collected. Uncoated amendments, sand, and peat had no influence on NO-N retention, whereas hexadecyltrimethylammonium-coated amendments reduced NO-N leaching to below detectable limits. Both coated and uncoated amendments reduced NH-N leaching, with zeolite reducing NH-N leached to near zero regardless of hexadecyltrimethylammonium coating. Pure sand resulted in a 13% reduction of applied orthophosphate-P leaching, whereas peat contributed to orthophosphate-P leaching. Surfactant-modified amendments reduced orthophosphate-P leaching by as much as 97%. Surfactant-modified soil amendments can reduce NO-N, NH-N, and orthophosphate-P leaching and, thus, may be a viable option for removing leached N and P before they enter surface or ground waters. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Application of Molecular Adsorber Coatings in Chamber A for the James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Abraham, Nithin S.

2017-01-01

As a coating made of highly porous zeolite materials, the Molecular Adsorber Coating (MAC) was developed to capture outgassed molecular contaminants, such as hydrocarbons and silicones. For spaceflight applications, the adsorptive capabilities of the coating can alleviate on-orbit outgassing concerns on or near sensitive surfaces and instruments within the spacecraft. Similarly, this sprayable paint technology has proven to be significantly beneficial for ground-based space applications, in particular, for vacuum chamber environments. This presentation describes the application of the MAC technology for the James Webb Space Telescope (JWST) at NASA Johnson Space Center (JSC). The coating was used as a mitigation tool to entrap outgassed contaminants, specifically silicone-based diffusion pump oil, from within JSCs cryogenic optical vacuum chamber test facility called Chamber A. This presentation summarizes the background, fabrication, installation, chemical analysis test results, and future plans for the MAC technology, which was effectively used to protect the JWST test equipment from vacuum chamber contamination. As a coating made of highly porous zeolite materials, the Molecular Adsorber Coating (MAC) was developed to capture outgassed molecular contaminants, such as hydrocarbons and silicones. For spaceflight applications, the adsorptive capabilities of the coating can alleviate on-orbit outgassing concerns on or near sensitive surfaces and instruments within the spacecraft. Similarly, this sprayable paint technology has proven to be significantly beneficial for ground-based space applications, in particular, for vacuum chamber environments. This presentation describes the application of the MAC technology for the James Webb Space Telescope (JWST) at NASA Johnson Space Center (JSC). The coating was used as a mitigation tool to entrap outgassed contaminants, specifically silicone-based diffusion pump oil, from within JSCs cryogenic optical vacuum chamber test facility called Chamber A. This presentation summarizes the background, fabrication, installation, chemical analysis test results, and future plans for the MAC technology, which was effectively used to protect the JWST test equipment from vacuum chamber contamination.

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.

Studies on Molecular and Ion Transport in Silicalite Membranes and Applications as Ion Separator for Redox Flow Battery

NASA Astrophysics Data System (ADS)

Yang, Ruidong

Microporous zeolite membranes have been widely studied for molecular separations based on size exclusion or preferential adsorption-diffusion mechanisms. The MFI-type zeolite membranes were also demonstrated for brine water desalination by molecular sieving effect. In this research, the pure silica MFI-type zeolite (i.e. silicalite) membrane has been for the first time demonstrated for selective permeation of hydrated proton (i.e. H3O+) in acidic electrolyte solutions. The silicalite membrane allows for permeation of H 3O+ ions, but is inaccessible to the large hydrated multivalent vanadium ions due to steric effect. The silicalite membrane has been further demonstrated as an effective ion separator in the all-vanadium redox flow battery (RFB).The silicalite is nonionic and its proton conductivity relies on the electric field-driven H3O+ transport through the sub nanometer-sized pores under the RFB operation conditions. The silicalite membrane displayed a significantly reduced self-discharge rate because of its high proton-to-vanadium ion transport selectivity. However, the nonionic nature of the silicalite membrane and very small diffusion channel size render low proton conductivity and is therefore inefficient as ion exchange membranes (IEMs) for practical applications. The proton transport efficiency may be improved by reducing the membrane thickness. However, the zeolite thin films are extremely fragile and must be supported on mechanically strong and rigid porous substrates. In this work, silicalite-Nafion composite membranes were synthesized to achieve a colloidal silicalite skin on the Nafion thin film base. The "colloidal zeolite-ionic polymer" layered composite membrane combines the advantages of high proton-selectivity of the zeolite layer and the mechanical flexibility and low proton transport resistance of the ionic polymer membrane. The composite membrane exhibited higher proton/vanadium ion separation selectivity and lower electrical resistance than the commercial Nafion 117 membrane. The high proton transport selectivity is a result of the molecular sieving effect between the H3O+ and multivalent vanadium ions by the zeolitic pores; thus the zeolite particles significantly reduced the effective membrane surface area for vanadium ion permeation. The low resistance of the composite membrane can be attributed to the reduced thickness of the Nafion base film and the thinness of the colloidal silicalite top layer. The composite membrane outperformed the Nafion 117 membrane in the vanadium RFB operation in terms of the overall charge-discharge energy efficiency. Efforts have been made in further investigation of ion and molecular transport diffusivity in the polycrystalline silicalite film using zeolite-coated optical fiber interferometers. A physical model has been established for analyzing the molecular diffusivity in the zeolite layer based on the temporal responses of the optical interferometric signals during the transient process of molecular sorption. Experiments were first carried out to study the diffusivity of isobutane to evaluate the effectiveness of the proposed optical method. The isobutane diffusivities in silicalite measured by this method were in good agreement with the values reported in literature. The zeolite coated fiber optic interferometer was however ineffective in monitoring ion sorption or ion exchange in the silicalite films. It is suggested that more sensitive fiber optic devices are needed for studying the ion diffusion.

The Wide Field/Planetary Camera 2 (WFPC-2) molecular adsorber

NASA Technical Reports Server (NTRS)

Barengoltz, Jack; Moore, Sonya; Soules, David; Voecks, Gerald

1995-01-01

A device has been developed at the Jet Propulsion Laboratory, California Institute of Technology, for the adsorption of contaminants inside a space instrument during flight. The molecular adsorber was developed for use on the Wide Field Planetary Camera 2, and it has been shown to perform at its design specifications in the WFPC-2. The basic principle of the molecular adsorber is a zeolite-coated ceramic honeycomb. The arrangement is efficient for adsorption and also provides the needed rigidity to retain the special zeolite coating during the launch vibrational environment. The adsorber, on other forms, is expected to be useful for all flight instruments sensitive to internal sources of contamination. Typically, some internal contamination is unavoidable. A common design solution is to increase the venting to the exterior. However, for truly sensitive instruments, the external contamination environment is more severe. The molecular adsorber acts as a one-way vent to solve this problem. Continued development is planned for this device.

Biofiltration of ammonia gas with sponge cubes coated with mixtures of activated carbon and zeolite.

PubMed

Kim, H; Xi, Q; Kim, Y J; Chung, S

2002-08-01

Removal of ammonia gas was investigated using a biofilter system packed with small cubes of polyurethane sponge that were coated with a powder mixture of activated carbon and natural zeolite. Experimental tests and measurements include removal efficiency, pH, metabolic products of ammonia and kinetic analysis. A removal efficiency over 90% can be obtained with ammonia concentrations below 150 ppm and at contact times above 23 sec.The ammonia adsorbing power of the present biocarrier can protect the biofilter system from a high ammonia shock loading in the feed. The maximum removal rate, Vm, obtained from the kinetic analysis is 8.47 g N (kg carrier)(-1) day(-1) and the saturation constant Ks is 50.36 ppm. Nitrite is produced dominantly during the entire experiments. The cell number of nitrifying bacteria is 1.58 x 10( cell (g carrier)(-1). The present synthetic bio-carrier is considered to be one of the best among bio-carriers that have been used for the biofiltration of ammonia.

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

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.

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.

Thiophenic compounds adsorption on Na(I)Y and rare earth exchanged Y zeolites: a density functional theory study.

PubMed

Gao, Xionghou; Geng, Wei; Zhang, Haitao; Zhao, Xuefei; Yao, Xiaojun

2013-11-01

We have theoretically investigated the adsorption of thiophene, benzothiophene, dibenzothiophene on Na(I)Y and rare earth exchanged La(III)Y, Ce(III)Y, Pr(III)Y Nd(III)Y zeolites by density functional theory calculations. The calculated results show that except benzothiophene adsorbed on Na(I)Y with a stand configuration, the stable adsorption structures of other thiophenic compounds on zeolites exhibit lying configurations. Adsorption energies of thiophenic compounds on the Na(I)Y are very low, and decrease with the increase of the number of benzene rings in thiophenic compounds. All rare earth exchanged zeolites exhibit strong interaction with thiophene. La(III)Y and Nd(III)Y zeolites are found to show enhanced adsorption energies to benzothiophene and Pr(III)Y zeolites are favorable for dibenzothiophene adsorption. The analysis of the electronic total charge density and electron orbital overlaps show that the thiophenic compounds interact with zeolites by π-electrons of thiophene ring and exchanged metal atom. Mulliken charge populations analysis reveals that adsorption energies are strongly dependent on the charge transfer of thiophenic molecule and exchanged metal atom.

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

Qian, Mr. Suxin; Gluesenkamp, Kyle R; Hwang, Dr. Yunho

Adsorption chillers are capable of utilizing inexpensive or free low grade thermal energy such as waste heat and concentrated solar thermal energy. Recently developed low regeneration temperature working pairs allow adsorption chillers to be driven by even lower temperature sources such as engine coolant and flat plate solar collectors. In this work, synthetic zeolite/water was implemented into a 3kW adsorption chiller test facility driven by hot water at 70 C. The zeolite was coated onto two fin-and-tube heat exchangers, with heat recovery employed between the two. Cyclic steady state parametric studies were experimentally conducted to evaluate the chiller's performance, resultingmore » in a cooling coefficient of performance (COP) ranging from 0.1 to 0.6 at different operating conditions. Its performance was compared with published values for other low regeneration temperature working pairs. The physical limitations of the synthetic zeolite revealed by parametric study results were then discussed. A novel operating control strategy was proposed based on the unique characteristics of synthetic zeolite. In addition, a physics-based COP prediction model was derived to predict the performance of the chiller under equilibrium loading, and was validated by the experiment results. This analytical expression can be used to estimate the cyclic steady state performance for future studies.« less

Gravity-dependent transport in industrial processes

NASA Technical Reports Server (NTRS)

Ostrach, Simon; Kamotani, Yasuhiro

1994-01-01

Gravity-dependent transport phenomena in various industrial processes are investigated in order to address a broader range of microgravity phenomena and to develop new applications of microgravity. A number of important topics are identified and analyzed in detail. The present article describes results on coating flow, zeolite growth, and rotating electrochemical system.

SYNTHESIS AND CORROSION RESISTANCE OF HIGH-SILICA ZEOLITE MTW, BEA, AND MFI COATINGS ON STEEL AND ALUMINUM. (R828134)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

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.

Synthesis and hydrophobic adsorption properties of microporous/mesoporous hybrid materials.

PubMed

Hu, Qin; Li, Jinjun; Qiao, Shizhang; Hao, Zhengping; Tian, Hua; Ma, Chunyan; He, Chi

2009-05-30

Hybrid materials of silicalite-1 (Sil-1)-coated SBA-15 particles (MSs) have been successfully synthesized by crystallization process under hydrothermal conditions. These MSs materials were characterized by X-ray diffraction, nitrogen adsorption/desorption and TEM techniques, which illustrated that the silicalite-1-coated SBA-15 particles were successfully prepared and had large pore volume and hierarchical pore size distribution. Further experimental studies indicated that longer crystallization time under basic condition caused the mesostructure of SBA-15 materials to collapse destructively and higher calcination temperature tended to disrupt the long-range mesoscopic order while they had little influence on the phase of microcrystalline silicalite-1 zeolite. The resultant MSs materials were investigated by estimating dynamic adsorption capacity under dry and wet conditions to evaluate their adsorptive and hydrophobic properties. The hydrophobicity index (HI) value followed the sequence of silicalite-1>MSs>SBA-15, which revealed that the SBA-15 particles coated with the silicalite-1 seeds enhanced the surface hydrophobicity, and also were consistent with FTIR results. Our studies show that MSs materials combined the advantages of the ordered mesoporous material (high adsorptive capacity, large pore volume) and silicalite-1 zeolite (super-hydrophobic property, high hydrothermal stability), and the presence of micropores directly led to an increase in the dynamic adsorption capacity of benzene under dry and wet conditions.

Vapor Responsive One-Dimensional Photonic Crystals from Zeolite Nanoparticles and Metal Oxide Films for Optical Sensing

PubMed Central

Lazarova, Katerina; Awala, Hussein; Thomas, Sebastien; Vasileva, Marina; Mintova, Svetlana; Babeva, Tsvetanka

2014-01-01

The preparation of responsive multilayered structures with quarter-wave design based on layer-by-layer deposition of sol-gel derived Nb2O5 films and spin-coated MEL type zeolite is demonstrated. The refractive indices (n) and thicknesses (d) of the layers are determined using non-linear curve fitting of the measured reflectance spectra. Besides, the surface and cross-sectional features of the multilayered structures are characterized by scanning electron microscopy (SEM). The quasi-omnidirectional photonic band for the multilayered structures is predicted theoretically, and confirmed experimentally by reflectance measurements at oblique incidence with polarized light. The sensing properties of the multilayered structures toward acetone are studied by measuring transmittance spectra prior and after vapor exposure. Furthermore, the potential of the one-dimensional photonic crystals based on the multilayered structure consisting of Nb2O5 and MEL type zeolite as a chemical sensor with optical read-out is discussed. PMID:25010695

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.

Thermodynamic properties of zeolites: low-temperature heat capacities and thermodynamic functions for phillipsite and clinoptilolite. Estimates of the thermochemical properties of zeolitic water at low temperature.

USGS Publications Warehouse

Hemingway, B.S.; Robie, R.A.

1984-01-01

Measured heat capacities between 15 and 305 K and calculated heat capacities, entropies, enthalpy functions and Gibbs energy functions are reported and analysed for phillipsite and clinoptilolite. - J.A.Z.

SEM-EDS Observation of Structure Changes in Synthetic Zeolites Modified for CO2 Capture Needs

NASA Astrophysics Data System (ADS)

Wdowin, Magdalena; Panek, Rafal; Franus, Wojciech

Carbon dioxide is the main greenhouse gas and its amount still increase in the atmosphere. Air pollution and greenhouse effect caused by CO2 emission have become a major threat to the environment on a global scale. Carbon dioxide sequestration (i.e. capture and consequently geological storage) is the key strategy within the portfolio of actions to reduce CO2 emission to the atmosphere. The most costly stage is capture of CO2, therefore there is a need to search new solutions of this technology. For this purpose it was examined Na-X synthetic zeolites, that were silver and PEI (polyethyleneimine) activated. SEM-EDS investigation enable to find a changes in structure of this materials after treatment. Where, as a result of silver activation from EDS analysis it is seen that Ag occur in Na-X structure, what indicate a substitution of Ag2+ for Na+ ions in crystal lattice. Analysing wt% the EDS analysis has shown that zeolite Na-X after silver impregnation becomes Ag-X zeolite. For Na-X-PEI activated it is observed a distinct organic compound in the form of coatings on Na-X crystals causing a sealing of pores in tested zeolite. Further examination of these materials concern determination of surface properties and experiments of CO2 sorption. But SEM-EDS analysis enable to determine the extent of activation, what is very important in determination of optimal conditions for such treatment in order to obtain better sorbent of CO2.

The influence of zeolites fly ash bead/TiO2 composite material surface morphologies on their adsorption and photocatalytic performance

NASA Astrophysics Data System (ADS)

Yang, Lu; Wang, Fazhou; Hakki, Amer; Macphee, Donald E.; Liu, Peng; Hu, Shuguang

2017-01-01

A low cost zeolite fly ash bead/TiO2 (ZFABT) composite materials with various surface structure features were prepared for describing those structures importance on TiO2 coating, adsorbability and photocatalytic performances. The results indicated that fly ash bead (FAB) surface was significantly altered by the precipitation/growth of secondary zeolite phases after alkali activation, which generates abundant open pores and stacked petal-liked spherical beads (∼2 μm, Sodalite zeolites). More importantly, this porosity increases as activation time was increased from 2 h to 12 h, through the precipitation of sodalite and then Na-P1 (lamellar crystals) and Na-X (octahedral crystals) zeolite structures. Compared to those of unsupported TiO2 or inactivated support/TiO2 samples, all of ZFABT samples exhibited a higher adsorption capacity and photocatalytic efficiency for RhB removal. However, adsorption is not only one factor to influence TiO2 surface reaction, the intraparticle diffusion rate of rhodamine B (RhB) molecules, and light penetration are also important parameters. Alkali activated 4 h ZFABT sample exhibited the highest photocatalytic activity, indicating its pore structure provided a better balance for those parameters to achieve a synergistic adsorption/photocatalytic process. The kinetics model suggested its high intraparticle diffusion rate allowed for more RhB molecules to easily reach the reaction surface, which is more important for high efficiency photocatalysis.

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.

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

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

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.

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.

Development of metal organic fromwork-199 immobilized zeolite foam for adsorption of common indoor VOCs.

PubMed

Saini, Vipin K; Pires, João

2017-05-01

Reticulated foam shaped adsorbents are more efficient for the removal of volatile organic compounds (VOCs), particularly from low VOC-concentration indoor air streams. In this study composite structure of zeolite and metal organic frameworks (MOFs), referred as ZMF, has been fabricated by immobilization of fine MOF-199 powder on foam shaped Zeolite Socony Mobil-5 (ZSM-5) Zeolitic structure, referred as ZF. The ZMF possess a uniform and well-dispersed coating of MOF-199 on the porous framework of ZF. It shows higher surface area, pore volume, and VOCs adsorption capacity, as compared to ZF-structure. Post-fabrication changes in selective adsorption properties of ZMF were studied with three common indoor VOCs (benzene, n-hexane, and cyclohexane), using gravimetric adsorption technique. The adsorption capacity of ZMF with different VOCs follow the order of benzene>n-hexane>cyclohexane. In comparison with MOF-199 and ZF, the composite structure ZMF shows improvement in selectivity for benzene from other two VOCs. Further, improvement in efficiency and stability of prepared ZMF was found to be associated with its high MOF loading capacity and unique morphological and structural properties. The developed composite structure with improved VOCs removal and recyclability could be a promising material for small to limited scale air pollution treatment units. Copyright © 2016. Published by Elsevier B.V.

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.

Influence of natural zeolite and nitrification inhibitor on organics degradation and nitrogen transformation during sludge composting.

PubMed

Zhang, Junya; Sui, Qianwen; Li, Kun; Chen, Meixue; Tong, Juan; Qi, Lu; Wei, Yuansong

2017-04-01

Sludge composting is one of the most widely used treatments for sewage sludge resource utilization. Natural zeolite and nitrification inhibitor (NI) are widely used during composting and land application for nitrogen conservation, respectively. Three composting reactors (A-the control, B-natural zeolite addition, and C-3,4-dimethylpyrazole phosphate (DMPP) addition) were established to investigate the influence of NI and natural zeolite addition on organics degradation and nitrogen transformation during sludge composting conducted at the lab scale. The results showed that, in comparison with the control, natural zeolite addition accelerated organics degradation and the maturity of sludge compost was higher, while the DMPP addition slowed down the degradation of organic matters. Meanwhile, the nitrogen transformation functional genes including those responses for nitrification (amoA and nxrA) and denitrification (narG, nirS, nirK, and nosZ) were quantified through quantitative PCR (qPCR) to investigate the effects of natural zeolites andDMPP addition on nitrogen transformation. Although no significant difference in the abundance of nitrogen transformation functional genes was observed between treatments, addition of both natural zeolite and DMPP increases the final total nitrogen content by 48.6% and 23.1%, respectively. The ability of natural zeolite for nitrogen conservation was due to the absorption of NH 3 by compost, and nitrogen conservation by DMPP was achieved by the source reduction of denitrification. Besides, it was assumed that the addition of natural zeolite and DMPP may affect the activity of these genes instead of the abundance.

Influence of natural zeolite and nitrification inhibitor on organics degradation and nitrogen transformation during sludge composting.

PubMed

Zhang, Junya; Sui, Qianwen; Li, Kun; Chen, Meixue; Tong, Juan; Qi, Lu; Wei, Yuansong

2016-01-01

Sludge composting is one of the most widely used treatments for sewage sludge resource utilization. Natural zeolite and nitrification inhibitor (NI) are widely used during composting and land application for nitrogen conservation, respectively. Three composting reactors (A--the control, B--natural zeolite addition, and C--3,4-dimethylpyrazole phosphate (DMPP) addition) were established to investigate the influence of NI and natural zeolite addition on organics degradation and nitrogen transformation during sludge composting conducted at the lab scale. The results showed that, in comparison with the control, natural zeolite addition accelerated organics degradation and the maturity of sludge compost was higher, while the DMPP addition slowed down the degradation of organic matters. Meanwhile, the nitrogen transformation functional genes including those responses for nitrification (amoA and nxrA) and denitrification (narG, nirS, nirK, and nosZ) were quantified through quantitative PCR (qPCR) to investigate the effects of natural zeolites and DMPP addition on nitrogen transformation. Although no significant difference in the abundance of nitrogen transformation functional genes was observed between treatments, addition of both natural zeolite and DMPP increases the final total nitrogen content by 48.6% and 23.1%, respectively. The ability of natural zeolite for nitrogen conservation was due to the absorption of NH3 by compost, and nitrogen conservation by DMPP was achieved by the source reduction of denitrification. Besides, it was assumed that the addition of natural zeolite and DMPP may affect the activity of these genes instead of the abundance.

Zeolite A functionalized with copper nanoparticles and graphene oxide for simultaneous electrochemical determination of dopamine and ascorbic acid.

PubMed

He, Ping; Wang, Wei; Du, Licheng; Dong, Faqin; Deng, Yuequan; Zhang, Tinghong

2012-08-20

A novel Cu-zeolite A/graphene modified glassy carbon electrode for the simultaneous electrochemical determination of dopamine (DA) and ascorbic acid (AA) has been described. The Cu-zeolite A/graphene composites were prepared using Cu(2+) functionalized zeolite A and graphene oxide as the precursor, and subsequently reduced by chemical agents. The composites were characterized by X-ray diffraction, Fourier transform infrared spectra and scanning electron microscopy. Based on the Cu-zeolite A/graphene-modified electrode, the potential difference between the oxidation peaks of DA and AA was over 200mV, which was adequate for the simultaneous electrochemical determination of DA and AA. Also the proposed Cu-zeolite/graphene-modified electrode showed higher electrocatalytic performance than zeolite/graphene electrode or graphene-modified electrode. The electrocatalytic oxidation currents of DA and AA were linearly related to the corresponding concentration in the range of 1.0×10(-7)-1.9×10(-5)M for DA and 2.0×10(-5)-2.0×10(-4)M for AA. Detection limits (S/N=3) were estimated to be 4.1×10(-8)M for DA and 1.1×10(-5)M for AA, respectively. Copyright © 2012 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.

Zeolitic imidazolate framework-8-derived N-doped porous carbon coated olive-shaped FeOx nanoparticles for lithium storage

NASA Astrophysics Data System (ADS)

Gan, Qingmeng; Zhao, Kuangmin; He, Zhen; Liu, Suqin; Li, Aikui

2018-04-01

We propose a new strategy to uniformly coat zeolitic imidazolate framework-8 (ZIF-8) on iron oxides containing no Zn to obtain an α-Fe2O3@ZIF-8 composite. After carbonization, the α-Fe2O3@ZIF-8 transforms into iron oxides@N-doped porous carbon (FeOx@NC). The uniform N-doped porous carbon layer gives rise to a superior electrical conductivity, highly-increased specific BET surface area (179.2 m2 g-1), and abundant mesopores for the FeOx@NC composite. When served as the LIB anode, the FeOx@NC shows a high reversible capacity (of 1064 mA h g-1 at 200 mA g-1), excellent rate performance (of 198.1 mA h g-1 at 10000 mA g-1) as well as brilliant long-term cyclability (with a capacity retention of 93.3% after 800 cycles), which are much better than those of the FeOx@C and pristine FeOx anodes. Specifically, the Li-ion intercalation pseudocapacitive behavior of the FeOx@NC anode is improved by this N-doped porous carbon coating, which is beneficial for rapid Li-ion insertion/extraction processes. The excellent electrochemical performance of FeOx@NC should be ascribed to the increased electrolyte penetration areas, improved electrical conductivity, boosted lithium storage kinetics, and shortened Li-ion transport length.

Application of the Molecular Adsorber Coating Technology on the Ionospheric Connection Explorer Program

NASA Technical Reports Server (NTRS)

Abraham, Nithin S.; Hasegawa, Mark M.; Secunda, Mark S.

2016-01-01

The Molecular Adsorber Coating (MAC) is a zeolite based highly porous coating technology that was developed by NASA Goddard Space Flight Center (GSFC) to capture outgassed contaminants, such as plastics, adhesives, lubricants, silicones, epoxies, potting compounds, and other similar materials. This paper describes the use of the MAC technology to address molecular contamination concerns on NASAs Ionospheric Connection Explorer (ICON) program led by the University of California (UC) Berkeleys Space Sciences Laboratory. The sprayable paint technology was applied onto plates that were installed within the instrument cavity of ICONs Far Ultraviolet Imaging Spectrograph (FUV). However, due to the instruments particulate sensitivity, the coating surface was vibrationally cleaned through simulated acoustics to reduce the risk of particle fall-out contamination. This paper summarizes the coating application efforts on the FUV adsorber plates, the simulated laboratory acoustic level cleaning test methods, particulation characteristics, and future plans for the MAC technology.

Application of the Molecular Adsorber Coating technology on the Ionospheric Connection Explorer program

NASA Astrophysics Data System (ADS)

Abraham, Nithin S.; Hasegawa, Mark M.; Secunda, Mark S.

2016-09-01

The Molecular Adsorber Coating (MAC) is a zeolite based highly porous coating technology that was developed by NASA Goddard Space Flight Center (GSFC) to capture outgassed contaminants, such as plastics, adhesives, lubricants, silicones, epoxies, potting compounds, and other similar materials. This paper describes the use of the MAC technology to address molecular contamination concerns on NASA's Ionospheric Connection Explorer (ICON) program led by the University of California (UC) Berkeley's Space Sciences Laboratory. The sprayable paint technology was applied onto plates that were installed within the instrument cavity of ICON's Far Ultraviolet Imaging Spectrograph (FUV). However, due to the instrument's particulate sensitivity, the coating surface was vibrationally cleaned through simulated acoustics to reduce the risk of particle fall-out contamination. This paper summarizes the coating application efforts on the FUV adsorber plates, the simulated laboratory acoustic level cleaning test methods, particulation characteristics, and future plans for the MAC technology.

Catalyst and method for reduction of nitrogen oxides

DOEpatents

Ott, Kevin C [Los Alamos, NM

2008-05-27

A Selective Catalytic Reduction (SCR) catalyst was prepared by slurry coating ZSM-5 zeolite onto a cordierite monolith, then subliming an iron salt onto the zeolite, calcining the monolith, and then dipping the monolith either into an aqueous solution of manganese nitrate and cerium nitrate and then calcining, or by similar treatment with separate solutions of manganese nitrate and cerium nitrate. The supported catalyst containing iron, manganese, and cerium showed 80 percent conversion at 113 degrees Celsius of a feed gas containing nitrogen oxides having 4 parts NO to one part NO.sub.2, about one equivalent ammonia, and excess oxygen; conversion improved to 94 percent at 147 degrees Celsius. N.sub.2O was not detected (detection limit: 0.6 percent N.sub.2O).

Catalyst and method for reduction of nitrogen oxides

DOEpatents

Ott, Kevin C [Los Alamos, NM

2008-08-19

A Selective Catalytic Reduction (SCR) catalyst was prepared by slurry coating ZSM-5 zeolite onto a cordierite monolith, then subliming an iron salt onto the zeolite, calcining the monolith, and then dipping the monolith either into an aqueous solution of manganese nitrate and cerium nitrate and then calcining, or by similar treatment with separate solutions of manganese nitrate and cerium nitrate. The supported catalyst containing iron, manganese, and cerium showed 80 percent conversion at 113 degrees Celsius of a feed gas containing nitrogen oxides having 4 parts NO to one part NO.sub.2, about one equivalent ammonia, and excess oxygen; conversion improved to 94 percent at 147 degrees Celsius. N.sub.2O was not detected (detection limit: 0.6 percent N.sub.2O).

Catalyst for reduction of nitrogen oxides

DOEpatents

Ott, Kevin C.

2010-04-06

A Selective Catalytic Reduction (SCR) catalyst was prepared by slurry coating ZSM-5 zeolite onto a cordierite monolith, then subliming an iron salt onto the zeolite, calcining the monolith, and then dipping the monolith either into an aqueous solution of manganese nitrate and cerium nitrate and then calcining, or by similar treatment with separate solutions of manganese nitrate and cerium nitrate. The supported catalyst containing iron, manganese, and cerium showed 80 percent conversion at 113 degrees Celsius of a feed gas containing nitrogen oxides having 4 parts NO to one part NO.sub.2, about one equivalent ammonia, and excess oxygen; conversion improved to 94 percent at 147 degrees Celsius. N.sub.2O was not detected (detection limit: 0.6 percent N.sub.2O).

Environmental Technology Verification: Test Report of Mobile Source Selective Catalytic Reduction--Nett Technologies, Inc., BlueMAX 100 version A urea-based selective catalytic reduction technology

EPA Science Inventory

Nett Technologies’ BlueMAX 100 version A Urea-Based SCR System utilizes a zeolite catalyst coating on a cordierite honeycomb substrate for heavy-duty diesel nonroad engines for use with commercial ultra-low–sulfur diesel fuel. This environmental technology verification (ETV) repo...

Zeolite-imidazolate framework (ZIF-8) membrane synthesis on a mixed-matrix substrate.

PubMed

Barankova, Eva; Pradeep, Neelakanda; Peinemann, Klaus-Viktor

2013-10-21

A thin, dense, compact and hydrogen selective ZIF-8 membrane was synthesized on a polymer/metal oxide mixed-matrix support by a secondary seeding method. The new concept of incorporating ZnO particles into the support and PDMS coating of the ZIF-8 layer is introduced to improve the preparation of ZIF-polymer composite membranes.

Enhancing the antibacterial activity of the gold standard intracanal medicament with incorporation of silver zeolite: An in vitro study.

PubMed

Ghatole, Kiran; Gowdra, Ramesh Halebathi Giriyappa; Azher, Samer; Sabharwal, Sumit; Singh, Veerandar T; Sundararajan, Bharath Vardhana

2016-01-01

Enterococcus faecalis is a persistent organism that plays a major role in the etiology of persistent periradicular lesions after root canal treatment has been associated with different forms of periradicular disease including primary endodontic infections and persistent infections. The present study compares the antibacterial activities of calcium hydroxide, calcium hydroxide mixed with silver zeolite, and calcium hydroxide mixed with 2% chlorhexidine against E. faecalis using direct contact test. The test materials of the in vitro experimental study were grouped as group 1-calcium hydroxide mixed with sterile water, group 2-2% silver zeolite added in calcium hydroxide mixed with sterile water, and group 3-calcium hydroxide mixed with 2% chlorhexidine. The bottom of microtiter plate were coated with freshly mixed tested material and a 10 μL of bacterial suspension was placed. After 1 h of incubation at 37°C, brain-heart infusion (BHI) broth (245 μL) was added and mixed for 2 min. These were designated as "subgroup 1" wells. A volume of 15 μL of broth then transferred from subgroup 1 wells to an adjacent set of four wells containing fresh BHI medium (215 μL); these wells were designated as "subgroup 2"' wells. The optical density was measured by a spectrophotometer after the first day, third day, and seventh day. One-way analysis of variance (ANOVA) and Tukey tests were performed for the analysis. Calcium hydroxide mixed with silver zeolite showed maximum antibacterial activity. Silver zeolite can be added in calcium hydroxide to enhance the latter's antibacterial activity against E. faecalis.

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.

Investigating the Influence of Temperature on the Kaolinite-Base Synthesis of Zeolite and Urease Immobilization for the Potential Fabrication of Electrochemical Urea Biosensors.

PubMed

Anderson, David Ebo; Balapangu, Srinivasan; Fleischer, Heidimarie N A; Viade, Ruth A; Krampa, Francis D; Kanyong, Prosper; Awandare, Gordon A; Tiburu, Elvis K

2017-08-08

Temperature-dependent zeolite synthesis has revealed a unique surface morphology, surface area and pore size which influence the immobilization of urease on gold electrode supports for biosensor fabrication. XRD characterization has identified zeolite X (Na) at all crystallization temperatures tested. However, N₂ adsorption and desorption results showed a pore size and pore volume of zeolite X (Na) 60 °C, zeolite X (Na) 70 °C and zeolite X (Na) 90 °C to range from 1.92 nm to 2.45 nm and 0.012 cm³/g to 0.061 cm³/g, respectively, with no significant differences. The specific surface area of zeolite X (Na) at 60, 70 and 90 °C was 64 m²/g, 67 m²/g and 113 m²/g, respectively. The pore size, specific surface area and pore volumes of zeolite X (Na) 80 °C and zeolite X (Na) 100 °C were dramatically increased to 4.21 nm, 295 m²/g, 0.762 cm³/g and 4.92 nm, 389 m²/g, 0.837 cm³/g, in that order. The analytical performance of adsorbed urease on zeolite X (Na) surface was also investigated using cyclic voltammetry measurements, and the results showed distinct cathodic and anodic peaks by zeolite X (Na) 80 °C and zeolite X (Na) 100 °C. These zeolites' molar conductance was measured as a function of urea concentration and gave an average polynomial regression fit of 0.948. The findings in this study suggest that certain physicochemical properties, such as crystallization temperature and pH, are critical parameters for improving the morphological properties of zeolites synthesized from natural sources for various biomedical applications.

Hydrophobic surface functionalization of Philippine natural zeolite for a targeted oil remediation application

NASA Astrophysics Data System (ADS)

Osonio, Airah P.; Olegario-Sanchez, Eleanor M.

2017-12-01

The objective of this study is to modify and compare the oil sorption capacity on the surface of natural zeolite (NZ) and functionalized natural zeolite (FNZ) and to compare with activated charcoal samples. The NZ samples were surface modified via esterification process and characterized using XRD, SEM, and IR spectroscopy. The NZ, FNZ and activated charcoal were then tested using ASTM method F726-12 to validate the oil sorption capacity and TGA was used for the oil selectivity of the adsorbents. The results indicate that FNZ has an improved oil/water adsorption capacity than NZ when functionalized with ester and has a comparable capacity with activated charcoal.

Theoretical studies of the nitrogen containing compounds adsorption behavior on Na(I)Y and rare earth exchanged RE(III)Y zeolites.

PubMed

Geng, Wei; Zhang, Haitao; Zhao, Xuefei; Zan, Wenyan; Gao, Xionghou; Yao, Xiaojun

2015-01-01

In this work, the adsorption behavior of nitrogen containing compounds including NH3, pyridine, quinoline, and carbazole on Na(I)Y and rare earth exchanged La(III)Y, Pr(III)Y, Nd(III)Y zeolites was investigated by density functional theory (DFT) calculations. The calculation results demonstrate that rare earth exchanged zeolites have stronger adsorption ability for nitrogen containing compounds than Na(I)Y. Rare earth exchanged zeolites exhibit strongest interaction with quinoline while weakest with carbazole. Nd(III)Y zeolites are found to have strongest adsorption to all the studied nitrogen containing compounds. The analysis of the electronic total charge density and electron orbital overlaps show that nitrogen containing compounds interact with zeolites by π-electrons of the compounds and the exchanged metal atom. Mulliken charge population analysis also proves that adsorption energies are strongly dependent on the charge transfer between the nitrogen containing molecules and exchanged metal atom in the zeolites.

Fuel Composition Analysis of Endothermically Heated JP-8 Fuel for Use in a Pulse Detonation Engine

DTIC Science & Technology

2008-06-01

detonation engine (PDE) was extracted via zeolite catalyst coated concentric tube-counter flow heat exchangers to produce supercritical pyrolytic conditions...gas chromatography flame ionization and thermal conductivity detectors ............................................. 68 Table B.1. Elemental bias... chromatography ...................... 98 Table D.1b. Products found in the liquid sample by gas chromatography (continued) ... 99 Table D.1c

Preparation of Iridescent 2D Photonic Crystals by Using a Mussel-Inspired Spatial Patterning of ZIF-8 with Potential Applications in Optical Switch and Chemical Sensor.

PubMed

Razmjou, Amir; Asadnia, Mohsen; Ghaebi, Omid; Yang, Hao-Cheng; Ebrahimi Warkiani, Majid; Hou, Jingwei; Chen, Vicki

2017-11-01

In this work, spatial patterning of a thin, dense, zeolitic imidazolate framework (ZIF-8) pattern was generated using photolithography and nanoscale (60 nm) dopamine coating. A bioinspired, unique, reversible, two-color iridescent pattern can be easily obtained for potential applications in sensing and photonics.

Nanoscale zero valent supported by Zeolite and Montmorillonite: Template effect of the removal of lead ion from an aqueous solution.

PubMed

Arancibia-Miranda, Nicolás; Baltazar, Samuel E; García, Alejandra; Muñoz-Lira, Daniela; Sepúlveda, Pamela; Rubio, María A; Altbir, Dora

2016-01-15

In this work, we have studied the Pb(2+) sorption capacity of Zeolite (Z) and Montmorillonite (Mt) functionalized with nanoscale zero-valent iron (nZVI), at 50% w/w, obtained by means of an impregnating process with a solvent excess. The composites were characterized by several techniques including X-ray diffraction; scanning electron microscopy (SEM); BET area; isoelectric point (IEP); and, finally a magnetic response. Comparatively significant differences in terms of electrophoretic and magnetic characteristics were found between the pristine materials and the composites. Both structures show a high efficiency and velocity in the removal of Pb(2+) up to 99.0% (200.0 ppm) after 40 min of reaction time. The removal kinetics of Pb(2+) is adequately described by the pseudo second-order kinetic model, and the maximum adsorbed amounts (q(e)) of this analyte are in close accordance with the experimental results. The intraparticle diffusion model shows that this is not the only rate-limiting step, this being the Langmuir model which was well adjusted to our experimental data. Therefore, maximum sorption capacities were found to be 115.1±11.0, 105.5±9.0, 68.3±1.3, 54.2±1.3, and 50.3±4.2 mg g(-1), for Mt-nZVI, Z-nZVI, Zeolite, Mt, and nZVI, respectively. The higher sorption capacities can be attributed to the synergetic behavior between the clay and iron nanoparticles, as a consequence of the clay coating process with nZVI. These results suggest that both composites could be used as an efficient adsorbent for the removal of lead from contaminated water sources. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of soot on ammonium nitrate species and NO2 selective catalytic reduction over Cu-zeolite catalyst-coated particulate filter.

PubMed

Mihai, Oana; Tamm, Stefanie; Stenfeldt, Marie; Olsson, Louise

2016-02-28

A selective catalytic reduction (SCR)-coated particulate filter was evaluated by means of dynamic tests performed using NH3, NO2, O2 and H2O. The reactions were examined both prior to and after soot removal in order to study the effect of soot on ammonium nitrate formation and decomposition, ammonia storage and NO2 SCR. A slightly larger ammonia storage capacity was observed when soot was present in the sample, which indicated that small amounts of ammonia can adsorb on the soot. Feeding of NO2 and NH3 in the presence of O2 and H2O at low temperature (150, 175 and 200°C) leads to a large formation of ammonium nitrate species and during the subsequent temperature ramp using H2O and argon, a production of nitrous oxides was observed. The N2O formation is often related to ammonium nitrate decomposition, and our results showed that the N2O formation was clearly decreased by the presence of soot. We therefore propose that in the presence of soot, there are fewer ammonium nitrate species on the surface due to the interactions with the soot. Indeed, we do observe CO2 production during the reaction conditions also at 150°C, which shows that there is a reaction with these species and soot. In addition, the conversion of NOx due to NO2 SCR was significantly enhanced in the presence of soot; we attribute this to the smaller amount of ammonium nitrate species present in the experiments where soot is available since it is well known that ammonium nitrate formation is a major problem at low temperature due to the blocking of the catalytic sites. Further, a scanning electron microscopy analysis of the soot particles shows that they are about 30-40 nm and are therefore too large to enter the pores of the zeolites. There are likely CuxOy or other copper species available on the outside of the zeolite crystallites, which could have been enhanced due to the hydrothermal treatment at 850°C of the SCR-coated filter prior to the soot loading. We therefore propose that soot is interacting with the ammonium nitrate species on the CuxOy or other copper species on the surface of the zeolite particles, which reduces the ammonium nitrate blocking of the catalyst and thereby results in higher NO2 SCR activity. © 2016 The Author(s).

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

Gianetto, A.; Farag, H.I.; Blasetti, A.P.

Changes of the relative importance of intradiffusion on USY zeolite crystals were studied as a way of affecting selectivity of catalytic cracking reactions. Zeolite crystals were synthesized (Si/Al = 2.4), activated and stabilized using ion exchange and steam calcination to obtain USSY (Ultra Stable Submicron Y) zeolites. After the activation the zeolites were pelletized (45--60 [mu]m particles). USSYs were tested in a novel Riser Simulator. Results obtained show that total aromatics (BTX), benzene, C[sub 4] olefins, and coke were significantly affected with the change of zeolite crystal sizes. Gasolines produced with USSY zeolites contain less aromatics and particularly lower benzenemore » levels. Experimental results were analyzed with a model including several lumps: unconverted gas oil, gasoline, light gases, and coke. This model also accounts for catalyst deactivation as a function of coke on catalyst. Various kinetic parameters were determined with their corresponding spans for the 95% level of confidence.« 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.

Investigating the Influence of Temperature on the Kaolinite-Base Synthesis of Zeolite and Urease Immobilization for the Potential Fabrication of Electrochemical Urea Biosensors

PubMed Central

Anderson, David Ebo; Balapangu, Srinivasan; Fleischer, Heidimarie N. A.; Viade, Ruth A.; Awandare, Gordon A.; Tiburu, Elvis K.

2017-01-01

Temperature-dependent zeolite synthesis has revealed a unique surface morphology, surface area and pore size which influence the immobilization of urease on gold electrode supports for biosensor fabrication. XRD characterization has identified zeolite X (Na) at all crystallization temperatures tested. However, N2 adsorption and desorption results showed a pore size and pore volume of zeolite X (Na) 60 °C, zeolite X (Na) 70 °C and zeolite X (Na) 90 °C to range from 1.92 nm to 2.45 nm and 0.012 cm3/g to 0.061 cm3/g, respectively, with no significant differences. The specific surface area of zeolite X (Na) at 60, 70 and 90 °C was 64 m2/g, 67 m2/g and 113 m2/g, respectively. The pore size, specific surface area and pore volumes of zeolite X (Na) 80 °C and zeolite X (Na) 100 °C were dramatically increased to 4.21 nm, 295 m2/g, 0.762 cm3/g and 4.92 nm, 389 m2/g, 0.837 cm3/g, in that order. The analytical performance of adsorbed urease on zeolite X (Na) surface was also investigated using cyclic voltammetry measurements, and the results showed distinct cathodic and anodic peaks by zeolite X (Na) 80 °C and zeolite X (Na) 100 °C. These zeolites’ molar conductance was measured as a function of urea concentration and gave an average polynomial regression fit of 0.948. The findings in this study suggest that certain physicochemical properties, such as crystallization temperature and pH, are critical parameters for improving the morphological properties of zeolites synthesized from natural sources for various biomedical applications. PMID:28786961

Magnetic spherical cores partly coated with periodic mesoporous organosilica single crystals.

PubMed

Li, Jing; Wei, Yong; Li, Wei; Deng, Yonghui; Zhao, Dongyuan

2012-03-07

Core-shell structured materials are of special significance in various applications. Until now, most reported core-shell structures have polycrystalline or amorphous coatings as their shell layers, with popular morphologies of microspheres or quasi-spheres. However, the single crystals, either mesoscale or atomic ones, are still rarely reported as shell layers. If single crystals can be coated on core materials, it would result in a range of new type core-shell structures with various morphologies, and probably more potential applications. In this work, we demonstrate that periodic mesoporous organosilica (PMO) single crystals can partly grow on magnetic microspheres to form incomplete Fe(3)O(4)@nSiO(2)@PMO core-shell materials in aqueous solution, which indeed is the first illustration that mesoporous single-crystal materials can be used as shell layers for preparation of core-shell materials. The achieved materials have advantages of high specific surface areas, good magnetic responses, embedded functional groups and cubic mesopore channels, which might provide them with various application conveniences. We suppose the partial growth is largely decided by the competition between growing tendency of single crystals and the resistances to this tendency. In principle, other single crystals, including a range of atomic single crystals, such as zeolites, are able to be developed into such core-shell structures.

Catalytic membrane reactor for water and wastewater treatment

NASA Astrophysics Data System (ADS)

Heng, Samuel

A double membrane reactor was fabricated and assessed for continuous treatment of water containing organic contaminants by ozonation. This innovative reactor consisted of a zeolite membrane prepared on the inner surface of a porous a-alumina support, which served as water selective extractor and active contactor, and a porous stainless membrane which was the ozone gas diffuser. The coupling of membrane separation and chemical oxidation was found to be highly beneficial to both processes. The total organic carbon (TOC) removal rate at the retentate was enhanced by up to 2.2 times, as compared to membrane ozonation. Simultaneously, clean water (< 2 mg C.L-1 ) was consistently produced on the permeate side, using a feed solution containing up to 1000 mg C.L-1, while the retentate was concentrated and treated. Most significantly, the addition of an adsorbing material, as a bed or a coated layer, onto the pores of the membrane support, was shown to further enhance TOC degradation, permeated TOC concentration, permeate flux, and moreover, ozone yield. The achievements of this project included: (1) The development of a novel low-temperature zeolite membrane activation method that generates consistently high quality membranes (i.e. high reproducibility and fewer defects). (2) The demonstration that gamma-alumina and gamma-alumina supported catalysts do not have significant activity and that the TOC removal enhancement usually observed during catalytic ozonation was due primarily to the contribution of adsorption and metal leaching. Thermogravimetric analysis (TGA) and elemental analysis (EA) of the spent catalyst showed that, during catalytic ozonation, oxygenated by-products of increased adsorbability were concentrated onto the gamma-alumina contactor, and were subsequently degraded. (3) The development of a method for coating high surface area gamma-alumina layers onto the grains of zeolite membrane support used as the active membrane contactor.

Modified zeolitic imidazolate framework-8 as solid-phase microextraction Arrow coating for sampling of amines in wastewater and food samples followed by gas chromatography-mass spectrometry.

PubMed

Lan, Hangzhen; Rönkkö, Tuukka; Parshintsev, Jevgeni; Hartonen, Kari; Gan, Ning; Sakeye, Motolani; Sarfraz, Jawad; Riekkola, Marja-Liisa

2017-02-24

In this study, a novel solid phase microextration (SPME) Arrow was prepared for the sampling of volatile low molecular weight alkylamines (trimethylamine (TMA) and triethylamine (TEA)) in wastewater, salmon and mushroom samples before gas chromatographic separation with mass spectrometer as detector. Acidified zeolitic imidazolate framework-8 (A-ZIF-8) was utilized as adsorbent and poly(vinyl chloride) (PVC) as the adhesive. The custom SPME Arrow was fabricated via a physical adhesion: (1) ZIF-8 particles were suspended in a mixture of tetrahydrofuran (THF) and PVC to form a homogeneous suspension, (2) a non-coated stainless steel SPME Arrow was dipped in the ZIF-8/PVC suspension for several times to obtain a uniform and thick coating, (3) the pore size of ZIF-8 was modified by headspace exposure to hydrochloric acid in order to increase the extraction efficiency for amines. The effect of ZIF-8 concentration in PVC solution, dipping cycles and aging temperature on extraction efficiency was investigated. In addition, sampling parameters such as NaCl concentration, sample volume, extraction time, potassium hydroxide concentration, desorption temperature and desorption time were optimized. The Arrow-to-Arrow reproducibilities (RSDs) for five ZIF-8 coated Arrows were 15.6% and 13.3% for TMA and TEA, respectively. The extraction with A-ZIF-8/PVC Arrow was highly reproducible for at least 130 cycles without noticeable decrease of performance (RSD<12.5%). Headspace SPME of 7.5mL sample solution with the fabricated ZIF-8 coated Arrow achieved linear ranges of 1-200ngmL -1 for both TMA and TEA. The limit of quantitation (LOQ) was 1ngmL -1 for both TMA and TEA. The method was successfully applied to the determination of TMA and TEA in wastewater, salmon and mushroom samples giving satisfactory selectivity towards the studied amines. Copyright © 2016 Elsevier B.V. All rights reserved.

In situ upgrading of whole biomass to biofuel precursors with low average molecular weight and acidity by the use of zeolite mixture

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

Ben, Haoxi; Huang, Fang; Li, Liwei

2015-09-09

The pyrolysis of whole biomass—pine wood and bark—with mordenite (M), beta (β) and Y zeolites has been examined at 600°C. The GPC results indicated that the pyrolysis oils upgraded by Y and β zeolites have a very low average molecular weight range (70–170 g mol –1). Several NMR methods have been employed to characterize the whole portion of pyrolysis products. After the use of these two zeolites (Y and β), the two main products from the pyrolysis of cellulose—levoglucosan and HMF—were eliminated; this indicates a significant deoxygenation process. When a mixture of zeolites (Y and M) was used, the upgradedmore » pyrolysis oil exhibited advantages provided by both zeolites; this pyrolysis oil represents a biofuel precursor that has a very low average molecular weight and a relatively low acidity. Finally, this study opens up a new way to upgrade pyrolysis oils by employing mixtures of different functional zeolites to produce biofuel/biochemical precursors from whole biomass.« less

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.

Metal Oxide Assisted Preparation of Core-Shell Beads with Dense Metal-Organic Framework Coatings for the Enhanced Extraction of Organic Pollutants.

PubMed

Del Rio, Mateo; Palomino Cabello, Carlos; Gonzalez, Veronica; Maya, Fernando; Parra, Jose B; Cerdà, Victor; Turnes Palomino, Gemma

2016-08-08

Dense and homogeneous metal-organic framework (MOF) coatings on functional bead surfaces are easily prepared by using intermediate sacrificial metal oxide coatings containing the metal precursor of the MOF. Polystyrene (PS) beads are coated with a ZnO layer to give ZnO@PS core-shell beads. The ZnO@PS beads are reactive in the presence of 2-methylimidazole to transform part of the ZnO coating into a porous zeolitic imidazolate framework-8 (ZIF-8) external shell positioned above the internal ZnO precursor shell. The obtained ZIF-8@ZnO@PS beads can be easily packed in column format for flow-through applications, such as the solid-phase extraction of trace priority-listed environmental pollutants. The prepared material shows an excellent permeance to flow when packed as a column to give high enrichment factors, facile regeneration, and excellent reusability for the extraction of the pollutant bisphenol A. It also shows an outstanding performance for the simultaneous enrichment of mixtures of endocrine disrupting chemicals (bisphenol A, 4-tert-octylphenol and 4-n-nonylphenol), facilitating their analysis when present at very low levels (<1 μg L(-1) ) in drinking waters. For the extraction of the pollutant bisphenol A, the prepared ZIF-8@ZnO@PS beads also show a superior extraction and preconcentration capacity to that of the PS beads used as precursors and the composite materials obtained by the direct growth of ZIF-8 on the surface of the PS beads in the absence of metal oxide intermediate coatings. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theoretical Investigation of Methane Hydroxylation over Isoelectronic [FeO]2+- and [MnO]+-Exchanged Zeolites Activated by N2O.

PubMed

Mahyuddin, M Haris; Shiota, Yoshihito; Staykov, Aleksandar; Yoshizawa, Kazunari

2017-09-05

While the most likely structure of the active site in iron-containing zeolites has been recently identified as [FeO] 2+ (Snyder et al. Nature 2016, 536, 317-321), the mechanism for the direct conversion of methane to methanol over this active species is still debatable between the direct-radical-rebound or nonradical (concerted) mechanism. Using density functional theory on periodic systems, we calculated the two reaction mechanisms over two d 4 isoelectronic systems, [FeO] 2+ and [MnO] + zeolites. We found that [FeO] 2+ zeolites favor the direct-radical-rebound mechanism with low CH 4 activation energies, while [MnO] + zeolites prefer the nonradical mechanism with higher CH 4 activation energies. These contrasts, despite their isoelectronic structures, are mainly due to the differences in the metal coordination number and O α (oxo) spin density. Moreover, molecular orbital analyses suggest that the zeolite steric hindrance further degrades the reactivity of [MnO] + zeolites toward methane. Two types of zeolite frameworks, i.e., medium-pore ZSM-5 (MFI framework) and small-pore SSZ-39 (AEI framework) zeolites, were evaluated, but no significant differences in the reactivity were found. The rate-determining reaction step is found to be methanol desorption instead of methane activation. Careful examination of the most stable sites hosting the active species and calculation for N 2 O decomposition over [Fe] 2+ -MFI and -AEI zeolites were also performed.

Studying Zeolite Catalysts with a 2D Model System

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

Boscoboinik, Anibal

2016-12-07

Anibal Boscoboinik, a materials scientist at Brookhaven’s Center for Functional Nanomaterials, discusses the surface-science tools and 2D model system he uses to study catalysis in nanoporous zeolites, which catalyze reactions in many industrial processes.

Multilevel organization in hybrid thin films for optoelectronic applications.

PubMed

Vohra, Varun; Bolognesi, Alberto; Calzaferri, Gion; Botta, Chiara

2009-10-20

In this work we report two simple approaches to prepare hybrid thin films displaying a high concentration of zeolite crystals that could be used as active layers in optoelectronic devices. In the first approach, in order to organize nanodimensional zeolite crystals of 40 nm diameter in an electroactive environment, we chemically modify their external surface and play on the hydrophilic/hydrophobic forces. We obtain inorganic nanocrystals that self-organize in honeycomb electroluminescent polymer structures obtained by breath figure formation. The different functionalizations of the zeolite surface result in different organizations inside the cavities of the polymeric structure. The second approach involving soft-litography techniques allows one to arrange single dye-loaded zeolite L crystals of 800 nm of length by mechanical loading into the nanocavities of a conjugated polymer. Both techniques result in the formation of thin hybrid films displaying three levels of organization: organization of the dye molecules inside the zeolite nanochannels, organization of the zeolite crystals inside the polymer cavities, and micro- or nanostructuration of the polymer.

Carbonic anhydrase inspired poly(N-vinylimidazole)/zeolite Zn-β hybrid membranes for CO2 capture.

PubMed

Liu, Yanni; Wang, Zhi; Shi, Mengqi; Li, Nan; Zhao, Song; Wang, Jixiao

2018-06-14

A carbonic anhydrase inspired material was developed by incorporating Zn(ii) ion exchanged zeolite β into poly(N-vinylimidazole) solution. The hydrophobic zeolite channels were designed to imitate the function of the hydrophobic pocket in carbonic anhydrase. The composite membrane prepared by casting the material on a polysulfone ultrafiltration membrane showed a high CO2 permeance of 4620 GPU with a high CO2/N2 selectivity of 224.

Studying Zeolite Catalysts with a 2D Model System

ScienceCinema

Boscoboinik, Anibal

2018-06-13

Anibal Boscoboinik, a materials scientist at Brookhaven’s Center for Functional Nanomaterials, discusses the surface-science tools and 2D model system he uses to study catalysis in nanoporous zeolites, which catalyze reactions in many industrial processes.

Framework Stability of Nanocrystalline NaY in Aqueous Solution at Varying pH

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

Petushkov, Anton; Freeman, Jasmine; Larsen, Sarah C.

Nanocrystalline zeolites (with crystal sizes of less than 50 nm) are versatile, porous nanomaterials with potential applications in a broad range of areas including bifunctional catalysis, drug delivery, environmental protection, and sensing, to name a few. The characterization of the properties of nanocrystalline zeolites on a fundamental level is critical to the realization of these innovative applications. Nanocrystalline zeolites have unique surface chemistry that is distinct from conventional microcrystalline zeolite materials and that will result in novel applications. In the proposed work, magnetic resonance techniques (solid state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR)) will be used tomore » elucidate the structure and reactivity of nanocrystalline zeolites and to motivate bifunctional applications. Density functional theory (DFT) calculations will enhance data interpretation through chemical shift, quadrupole coupling constant, g-value and hyperfine calculations.« less

Impact of zeolite-Y framework on the geometry and reactivity of Ru (III) benzimidazole complexes - A DFT study

NASA Astrophysics Data System (ADS)

Selvaraj, Tamilmani; Rajalingam, Renganathan; Balasubramanian, Viswanathan

2018-03-01

A detailed comparative Density Functional Theory (DFT) study is made to understand the structural changes of the guest complex due to steric and electronic interactions with the host framework. In this study, Ru(III) benzimidazole and 2- ethyl Ru(III) benzimidazole complexes encapsulated in a supercage of zeolite Y. The zeolitic framework integrity is not disturbed by the intrusion of the large guest complex. A blue shift in the d-d transition observed in the UV-Visible spectroscopic studies of the zeolite encapsulated complexes and they shows a higher catalytic efficiency. Encapsulation of zeolite matrix makes the metal center more viable to nucleophilic attack and favors the phenol oxidation reaction. Based on the theoretical calculations, transition states and structures of reaction intermediates involved in the catalytic cycles are derived.

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.

Sensitivity differences between microporous NaY and hierarchical ZSM-5 modified electrodes as ammonia gas sensor

NASA Astrophysics Data System (ADS)

Lisnawati, E.; Agustin, I.; Krisnandi, Y. K.; Triyono, D.

2017-07-01

The hierarchical ZSM-5 had been successfully synthesized with double template using a hydrotermal method and microporous NaY zeolite had been successfully synthesized using a sol-gel method. XRD pattern confirmed hat the as-synthesized materials were ZSM-5 and NaY zeolites. SEM images of ZSM-5 showed that it has a hexagonal shape, which can be called coffin type,and rough surface. The EDS elemental analysis gives Si/Al molar ratio of 24.2. On the other hand, NaY crystals were intergrown in cuboid shapes with Si/Al molar ratio of 2. ZSM-5 and NaY were coated onto the surface of Interdigitated Capacitor (IDC) pattern made of gold/silver/quartz through spin coating method. IDC, ZSM-5/IDC and NaY/IDC were tested using Electrochemical Impedance Spectroscopy (EIS) method. The composite has different sensitivity in range concentration of ammonia 20-300 ppm. IDC has no significant effect of the presence of various concentrations, NaY/IDC and ZSM-5/IDC composite have frequency 100 Hz with R2 = 0.8312 and R2 = 0.8037. The NaY/IDC has higher sensitivity compared toZSM-5/IDC, this could be caused by the higher polarity of NaY compared to ZSM-5 to attract ammonia.

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

Oleksiak, Matthew D.; Ghorbanpour, Arian; Conato, Marlon T.

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 obtain 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. Here, 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 H2O relative to other light gasesmore » (e.g., H2, N2, CO2).« less

Application of nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, UV-Visible spectroscopy and kinetic modeling for elucidation of adsorption chemistry in uptake of tetracycline by zeolite beta.

PubMed

Kang, Jin; Liu, Huijuan; Zheng, Yu-Ming; Qu, Jiuhui; Chen, J Paul

2011-02-01

Extensive usage of tetracycline has resulted in its contamination in surface water and groundwater. The adsorption of tetracycline on zeolite beta was systematically investigated for the decontamination of the antibiotic polluted water in this study. Ninety percent of uptake by the zeolite beta occured in 0.25h, and the adsorption equilibrium was obtained within 3h, which was well described by an intraparticle diffusion model. The adsorption generally increased when pH was increased from 4.0 to 5.0, and then decreased significantly as the pH was further increased, which was caused by the pH-dependent speciation of tetracycline and surface charge of zeolite beta. Both Freundlich and Langmuir equations well described the adsorption isotherm. A thermodynamic analysis showed that the sorption process was spontaneous and endothermic. Aluminum atoms in the zeolite played a crucial role in the uptake; the adsorption increased with the increasing aluminum content in zeolite. The UV-Visible spectroscopy study showed that the spectra of tetracycline changed upon the interaction with zeolite beta, which could be ascribed to the formation of complexes of tetracycline and aluminum atoms in the zeolite surface. Nuclear magnetic resonance spectroscopy study further confirmed the participation of Al in the tetracycline adsorption. Fourier transform infrared spectroscopy studies showed that the amino functional groups in tetracycline were involved in the complexation with the zeolite surface. Copyright © 2010 Elsevier Inc. All rights reserved.

Structure-Property Relationships of Inorganically Surface-Modified Zeolite Molecular Sieves for Nanocomposite Membrane Fabrication

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

Lydon, Megan E; Unocic, Kinga A; Jones, Christopher W

2012-01-01

A multiscale experimental study of the structural, compositional, and morphological characteristics of aluminosilicate (LTA) and pure-silica (MFI) zeolite materials surface-modified with MgO{sub x}H{sub y} nanostructures is presented. These characteristics are correlated with the suitability of such materials in the fabrication of LTA/Matrimid mixed-matrix membranes (MMMs) for CO{sub 2}/CH{sub 4} separations. The four functionalization methods studied in this work produce surface nanostructures that may appear superficially similar under SEM observation but in fact differ considerably in shape, size, surface coverage, surface area/roughness, degree of attachment to the zeolite surface, and degree of zeolite pore blocking. The evaluation of these characteristics bymore » a combination of TEM, HRTEM, N{sub 2} physisorption, multiscale compositional analysis (XPS, EDX, and ICP-AES elemental analysis), and diffraction (ED and XRD) allows improved understanding of the origin of disparate gas permeation properties observed in MMMs made with four types of surface-modified zeolite LTA materials, as well as a rational selection of the method expected to result in the best enhancement of the desired properties (in the present case, CO{sub 2}/CH{sub 4} selectivity increase without sacrificing permeability). A method based on ion exchange of the LTA with Mg{sup 2+}, followed by base-induced precipitation and growth of MgOxHy nanostructures, deemed 'ion exchange functionalization' here, offers modified particles with the best overall characteristics resulting in the most effective MMMs. LTA/Matrimid MMMs containing ion exchange functionalized particles had a considerably higher CO{sub 2}/CH{sub 4} selectivity (40) than could be obtained with the other functionalization techniques (30), while maintaining a CO{sub 2} permeability of 10 barrers. A parallel study on pure silica MFI surface nanostructures is also presented to compare and contrast with the zeolite LTA case.« less

Understanding of local structure-function relationships of zeolites used in industry through polarized raman spectroscopy

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

Rivera, O.; Lascola, R.; Fessler, K.

The overall objective of this project is to optics procurement and instrumental setup completed in Robert Lascola’s laboratory. An Ondax THz-Raman probe was installed in order to obtain Raman terahertz spectra of commercially available Zeolites.

Quantification of thickness and wrinkling of exfoliated two-dimensional zeolite nanosheets

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

Kumar, Prashant; Agrawal, Kumar Varoon; Tsapatsis, Michael

Some two-dimensional (2D) exfoliated zeolites are single- or near single-unit cell thick silicates that can function as molecular sieves. Although they have already found uses as catalysts, adsorbents and membranes precise determination of their thickness and wrinkling is critical as these properties influence their functionality. Here we demonstrate a method to accurately determine the thickness and wrinkles of a 2D zeolite nanosheet by comprehensive 3D mapping of its reciprocal lattice. Since the intensity modulation of a diffraction spot on tilting is a fingerprint of the thickness, and changes in the spot shape are a measure of wrinkling, this mapping ismore » achieved using a large-angle tilt-series of electron diffraction patterns. As a result, application of the method to a 2D zeolite with MFI structure reveals that the exfoliated MFI nanosheet is 1.5 unit cells (3.0 nm) thick and wrinkled anisotropically with up to 0.8 nm average surface roughness.« less

Quantification of thickness and wrinkling of exfoliated two-dimensional zeolite nanosheets

DOE PAGES

Kumar, Prashant; Agrawal, Kumar Varoon; Tsapatsis, Michael; ...

2015-05-11

Some two-dimensional (2D) exfoliated zeolites are single- or near single-unit cell thick silicates that can function as molecular sieves. Although they have already found uses as catalysts, adsorbents and membranes precise determination of their thickness and wrinkling is critical as these properties influence their functionality. Here we demonstrate a method to accurately determine the thickness and wrinkles of a 2D zeolite nanosheet by comprehensive 3D mapping of its reciprocal lattice. Since the intensity modulation of a diffraction spot on tilting is a fingerprint of the thickness, and changes in the spot shape are a measure of wrinkling, this mapping ismore » achieved using a large-angle tilt-series of electron diffraction patterns. As a result, application of the method to a 2D zeolite with MFI structure reveals that the exfoliated MFI nanosheet is 1.5 unit cells (3.0 nm) thick and wrinkled anisotropically with up to 0.8 nm average surface roughness.« less

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.

Mars weathering analogs - Secondary mineralization in Antarctic basalts

NASA Technical Reports Server (NTRS)

Berkley, J. L.

1982-01-01

Alkalic basalt samples from Ross Island, Antarctica, are evaluated as terrestrial analogs to weathered surface materials on Mars. Secondary alteration in the rocks is limited to pneumatolytic oxidation of igneous minerals and glass, rare groundmass clay and zeolite mineralization, and hydrothermal minerals coating fractures and vesicle surfaces. Hydrothermal mineral assemblages consist mainly of K-feldspar, zeolites (phillipsite and chabazite), calcite, and anhydrite. Low alteration rates are attributed to cold and dry environmental factors common to both Antarctica and Mars. It is noted that mechanical weathering (aeolian abrasion) of Martian equivalents to present Antarctic basalts would yield minor hydrothermal minerals and local surface fines composed of primary igneous minerals and glass but would produce few hydrous products, such as palagonite, clay or micas. It is thought that leaching of hydrothermal vein minerals by migrating fluids and redeposition in duricrust deposits may represent an alternate process for incorporating secondary minerals of volcanic origin into Martian surface fines.

Surface modification of a natural zeolite by treatment with cold oxygen plasma: Characterization and application in water treatment

NASA Astrophysics Data System (ADS)

De Velasco-Maldonado, Paola S.; Hernández-Montoya, Virginia; Montes-Morán, Miguel A.; Vázquez, Norma Aurea-Rangel; Pérez-Cruz, Ma. Ana

2018-03-01

In the present work the possible surface modification of natural zeolite using cold oxygen plasma was studied. The sample with and without treatment was characterized using nitrogen adsorption isotherms at -196 °C, FT-IR spectroscopy, SEM/EDX analysis and X-Ray Diffraction. Additionally, the two samples were used for the removal of lead and acid, basic, reactive and food dyes in batch systems. The natural zeolite was found to be a mesoporous material with a low specific surface area (23 m2/g). X-ray patterns confirmed that clinoptilolite was the main crystal structure present in the natural zeolite. The molecular properties of dyes and the zeolitic structure were studied using molecular simulation, with the purpose to understand the adsorption mechanism. The results pointed out that only the roughness of the clinoptilolite was affected by the plasma treatment, whereas the specific surface area, chemical functionality and crystal structure remained constant. Finally, adsorption results confirmed that the plasma treatment had no significant effects on the dyes and lead retention capacities of the natural zeolite.

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.

Separation of BSA through FAU-type zeolite ceramic composite membrane formed on tubular ceramic support: Optimization of process parameters by hybrid response surface methodology and biobjective genetic algorithm.

PubMed

Vinoth Kumar, R; Ganesh Moorthy, I; Pugazhenthi, G

2017-08-09

In this study, Faujasite (FAU) zeolite was coated on low-cost tubular ceramic support as a separating layer through hydrothermal route. The mixture of silicate and aluminate solutions was used to create a zeolitic separation layer on the support. The prepared zeolite ceramic composite membrane was characterized using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), particle size distribution (PSD), field emission scanning electron microscopy (FESEM), and zeta potential measurements. The porosity of ceramic support (53%) was reduced by the deposition of FAU (43%) zeolite layer. The pore size and water permeability of the membrane were evaluated as 0.179 µm and 1.62 × 10 -7  m 3 /m 2  s kPa, respectively, which are lower than that of the support (pore size of 0.309 µm and water permeability of 5.93 × 10 -7  m 3 /m 2  s kPa). The permeate flux and rejection potential of the prepared membrane were evaluated by microfiltration of bovine serum albumin (BSA). To study the influences of three independent variables such as operating pressure (68.94-275.79 kPa), concentration of BSA (100-500 ppm), and solution pH (2-4) on permeate flux and percentage of rejection, the response surface methodology (RSM) was used. The predicted models for permeate flux and rejection were further subjected to biobjective genetic algorithm (GA). The hybrid RSM-GA approach resulted in a maximum permeate flux of 2.66 × 10 -5  m 3 /m 2  s and BSA rejection of 88.02%, at which the optimum conditions were attained as 100 ppm BSA concentration, 2 pH solution, and 275.79 kPa applied pressure. In addition, the separation efficiency was compared with other membranes applied for BSA separation to know the potential of the fabricated FAU zeolite ceramic composite membrane.

The Use of the Molecular Adsorber Coating Technology to Mitigate Vacuum Chamber Contamination During Pathfinder Testing for the James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Abraham, Nithin S.; Hasegawa, Mark M.; Wooldridge, Eve M.; Henderson-Nelson, Kelly A.

2016-01-01

As a coating made of highly porous zeolite materials, the Molecular Adsorber Coating (MAC) was developed to capture outgassed molecular contaminants, such as hydrocarbons and silicones. For spaceflight applications, the adsorptive capabilities of the coating can alleviate on-orbit outgassing concerns on or near sensitive surfaces and instruments within the spacecraft. Similarly, this sprayable paint technology has proven to be significantly beneficial for ground based space applications, in particular, for vacuum chamber environments. This paper describes the recent use of the MAC technology during Pathfinder testing of the Optical Ground Support Equipment (OGSE) for the James Webb Space Telescope (JWST) at NASA Johnson Space Center (JSC). The coating was used as a mitigation tool to entrap persistent outgassed contaminants, specifically silicone based diffusion pump oil, from within JSC's cryogenic optical vacuum chamber test facility called Chamber A. This paper summarizes the sample fabrication, installation, laboratory testing, post-test chemical analysis results, and future plans for the MAC technology, which was effectively used to protect the JWST test equipment from vacuum chamber contamination.

The use of the Molecular Adsorber Coating technology to mitigate vacuum chamber contamination during Pathfinder testing for the James Webb Space Telescope

NASA Astrophysics Data System (ADS)

Abraham, Nithin S.; Hasegawa, Mark M.; Wooldridge, Eve M.; Henderson-Nelson, Kelly A.

2016-09-01

As a coating made of highly porous zeolite materials, the Molecular Adsorber Coating (MAC) was developed to capture outgassed molecular contaminants, such as hydrocarbons and silicones. For spaceflight applications, the adsorptive capabilities of the coating can alleviate on-orbit outgassing concerns on or near sensitive surfaces and instruments within the spacecraft. Similarly, this sprayable paint technology has proven to be significantly beneficial for ground based space applications, in particular, for vacuum chamber environments. This paper describes the recent use of the MAC technology during Pathfinder testing of the Optical Ground Support Equipment (OGSE) for the James Webb Space Telescope (JWST) at NASA Johnson Space Center (JSC). The coating was used as a mitigation tool to entrap persistent outgassed contaminants, specifically silicone based diffusion pump oil, from within JSC's cryogenic optical vacuum chamber test facility called Chamber A. This paper summarizes the sample fabrication, installation, laboratory testing, post-test chemical analysis results, and future plans for the MAC technology, which was effectively used to protect the JWST test equipment from vacuum chamber contamination.

Diamond or Diamond Like Carbon Coated Chemical Sensors and a Method of Making Same

DTIC Science & Technology

1997-04-30

will cause a synchronous machanical deformation of the substrate with a coincident generation of an acoustic wave in the material. The time 25...light may be altered and the change detetted by some optically sensitive detector. Figs. 1(a) and (b) show a basic acoustic cher.ical senscr 10...bond basic analytes are zeolites, fluoropolyol and other fluorinated polyols. Suitable chemoselective films for hydrogen bond acidic analytes are

Catalytic Combustion of Ethanol and Butanol

DTIC Science & Technology

2009-09-01

demonstrated 75% conversion of ethanol. I then selected a more active rhodium -coated alumina foam with a larger surface area and attained 100...catalysts composed of thermally stabilized, ion-exchanged zeolite, palladium on stabilized alumina, and catalysts doped with cerium (Ce) and nickel...platinum mesh weighed about 0.50 g and was roughly 0.5 mm thick. The rhodium (Rh)/aluminum oxide (Al2O3) foam contained 0.061 g of Rh and was prepared

Effect of Chromate and Chromate-Free Organic Coatings on Corrosion Fatigue of an Aluminum Alloy

DTIC Science & Technology

2012-02-20

Investigations of alloy AA7075 corrosion in acid rain solution, inhibited by chromate-free blends of zinc phosphate with bentonite, zeolite and calcium...with solution components. Single use of zinc phosphate and these ion exchanged pigments for corrosion inhibition do not provide desired effect...primer performance against corrosion fatigue cracking under a commercial polyurethane topcoat. As a control , they used samples of chromated AA2024

CO2 sorption on surface-modified carbonaceous support: Probing the influence of the carbon black microporosity and surface polarity

NASA Astrophysics Data System (ADS)

Gargiulo, Valentina; Alfè, Michela; Ammendola, Paola; Raganati, Federica; Chirone, Riccardo

2016-01-01

The use of solid sorbents is a convenient option in post-combustion CO2 capture strategies. Sorbents selection is a key point because the materials are required to be both low-cost and versatile in typical post-combustion conditions in order to guarantee an economically advantageous overall process. This work compares strategies to tailor the chemico-physical features of carbon black (CB) by surface-modification and/or coating with a CO2-sorbent phase. The influence of the CB microporosity, enhanced by chemical/thermal treatments, is also taken into account. Three CB surface modifications are performed and compared: (i) oxidation and functionalization with amino-groups, (ii) coating with iron oxides and (iii) impregnation with an ionic liquid (IL). The CO2 capture performance is evaluated on the basis of the breakthrough curves measured at atmospheric pressure and room temperature in a lab-scale fixed bed micro-reactor. Most of tested solids adsorb a CO2 amount significantly higher than a 13X zeolite and DARCO FGD (Norit) activated carbon (up to 4 times more in the best case). The sorbents bearing basic functionalities (amino-groups and IL) exhibit the highest CO2 sorption capacity. The use of a microporous carbonaceous support limits the accessibility of CO2 toward the adsorbing phase (IL or FM) lowering the number of accessible binding sites for CO2.

Black Molecular Adsorber Coatings for Spaceflight Applications

NASA Technical Reports Server (NTRS)

Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

2014-01-01

The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

Black molecular adsorber coatings for spaceflight applications

NASA Astrophysics Data System (ADS)

Abraham, Nithin S.; Hasegawa, Mark M.; Straka, Sharon A.

2014-09-01

The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

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.

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 IMPACT OF BLENDING RESIDUAL SOLIDS FROM TANKS 18/19 MOUNDS WITH TANK 7 OPERATIONS

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

Eibling, R; Erich Hansen, E; Bradley Pickenheim, B

2007-03-29

High level waste tanks 18F and 19F have residual mounds of waste which may require removal before the tanks can be closed. Conventional slurry pump technology, previously used for waste removal and tank cleaning, has been incapable of removing theses mounds from tanks 18F and 19F. A mechanical cleaning method has been identified that is potentially capable of removing and transferring the mound material to tank 7F for incorporation in a sludge batch for eventual disposal in high level waste glass by the Defense Waste Processing Facility. The Savannah River National Laboratory has been requested to evaluate whether the materialmore » transferred from tanks 18F/19F by the mechanical cleaning technology can later be suspended in Tank 7F by conventional slurry pumps after mixing with high level waste sludge. The proposed mechanical cleaning process for removing the waste mounds from tanks 18 and 19 may utilize a high pressure water jet-eductor that creates a vacuum to mobilize solids. The high pressure jet is also used to transport the suspended solids. The jet-eductor system will be mounted on a mechanical crawler for movement around the bottom of tanks 18 and 19. Based on physical chemical property testing of the jet-eductor system processed IE-95 zeolite and size-reduced IE-95 zeolite, the following conclusions were made: (1) The jet-eductor system processed zeolite has a mean and median particle size (volume basis) of 115.4 and 43.3 microns in water. Preferential settling of these large particles is likely. (2) The jet-eductor system processed zeolite rapidly generates settled solid yield stresses in excess of 11,000 Pascals in caustic supernates and will not be easily retrieved from Tank 7 with the existing slurry pump technology. (3) Settled size-reduced IE-95 zeolite (less than 38 microns) in caustic supernate does not generate yield stresses in excess of 600 Pascals in less than 30 days. (4) Preferential settling of size-reduced zeolite is a function of the amount of sludge and the level of dilution for the mixture. (5) Blending the size-reduced zeolite into larger quantities of sludge can reduce the amount of preferential settling. (6) Periodic dilution or resuspension due to sludge washing or other mixing requirements will increase the chances of preferential settling of the zeolite solids. (7) Mixtures of Purex sludge and size-reduced zeolite did not produce yield stresses greater than 200 Pascals for settling times less than thirty days. Most of the sludge-zeolite blends did not exceed 50 Pascals. These mixtures should be removable by current pump technology if sufficient velocities can be obtained. (8) The settling rate of the sludge-zeolite mixtures is a function of the ionic strength (or supernate density) and the zeolite- sludge mixing ratio. (9) Simulant tests indicate that leaching of Si may be an issue for the processed Tank 19 mound material. (10) Floating zeolite fines observed in water for the jet-eductor system and size-reduced zeolite were not observed when the size-reduced zeolite was blended with caustic solutions, indicating that the caustic solutions cause the fines to agglomerate. Based on the test programs described in this report, the potential for successfully removing Tank 18/19 mound material from Tank 7 with the current slurry pump technology requires the reduction of the particle size of the Tank 18/19 mound material.« less

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.

Improving the indoor air quality of respiratory type of medical facility by zeolite filtering.

PubMed

Shen, Jyun-Hong; Wang, Yeoung-Sheng; Lin, Jhan-Ping; Wu, Sheng-Hung; Horng, Jao-Jia

2014-01-01

This study investigated the indoor air quality (IAQ) conditions of carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), formaldehyde (HCHO), total volatile organic compounds (TVOCs), and bio-aerosols (bacteria and fungi) in a respiratory type of medical facility in Chia-Yi County in southern Taiwan. Among those IAQ conditions, the concentrations of CO, O3, and HCHO exceeded the regulation values of the Taiwan Environmental Protection Administration (EPA) mostly in the morning. The concentrations of bacteria and fungi did not exceed the regulation values but still posed potential health and environment problems for workers, patients, and visitors. Therefore, self-made silver-coated zeolite (AgZ) was used as a filter material in air cleaners to remove bio-aerosols in the respiratory care ward (RCW), and the removals were still effective after 120 hr. The cumulative bio-aerosol removals for bacteria and fungi were 900 and 1,088 colony-forming units (CFU) g(-1) after 24 hr and were above 3,100 and 2,700 CFU g(-1) after 120 hr. From the research results, it is suggested that AgZ filtering could be used as a feasible engineering measure for hospitals to control their bacteria and fungi parameters in IAQ management. Hospitals should maintain their environmental management and monitoring programs and use different engineering measures to improve different IAQ parameters. This study investigated the IAQ conditions in the field at a hospital in Chia-Yi County in southern Taiwan. Although concentrations of most parameters were still within the regulation values, the concentrations of CO, O3, and HCHO were partially exceeded. We propose a method using an air cleaner with silver-coated zeolite (AgZ) as a possible engineering measure, and there were effective reductions of bacteria and fungi to lower levels with antibacterial effects after 120 hr. Furthermore, this study implies that hospitals should continuously maintain environmental monitoring programs and adopt optimal engineering measures for different needs.

A comparative study of ozonation, iron coated zeolite catalyzed ozonation and granular activated carbon catalyzed ozonation of humic acid.

PubMed

Gümüş, Dilek; Akbal, Feryal

2017-05-01

This study compares ozonation (O 3 ), iron coated zeolite catalyzed ozonation (ICZ-O 3 ) and granular activated carbon catalyzed ozonation (GAC-O 3 ) for removal of humic acid from an aqueous solution. The results were evaluated by the removal of DOC that specifies organic matter, UV 254 absorbance, SUVA (Specific Ultraviolet Absorbance at 254 nm) and absorbance at 436 nm. When ozonation was used alone, DOC removal was 21.4% at an ozone concentration of 10 mg/L, pH 6.50 and oxidation time of 60 min. The results showed that the use of ICZ or GAC as a catalyst increased the decomposition of humic acid compared to ozonation alone. DOC removal efficiencies were 62% and 48.1% at pH 6.5, at a catalyst loading of 0.75 g/L, and oxidation time of 60 min for ICZ and GAC, respectively. The oxidation experiments were also carried out using <100 kDa and <50 kDa molecular size fractions of humic acid in the presence of ICZ or GAC. Catalytic ozonation also yielded better DOC and UV 254 reduction in both <50 kDa and <100 kDa fractions of HA compared to ozonation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silver Clusters in Zeolites: From Self-Assembly to Ground-Breaking Luminescent Properties.

PubMed

Coutiño-Gonzalez, Eduardo; Baekelant, Wouter; Steele, Julian A; Kim, Cheol Woong; Roeffaers, Maarten B J; Hofkens, Johan

2017-09-19

Interest for functional silver clusters (Ag-CLs) has rapidly grown over years due to large advances in the field of nanoscale fabrication and materials science. The continuous development of strategies to fabricate small-scale silver clusters, together with their interesting physicochemical properties (molecule-like discrete energy levels, for example), make them very attractive for a wide variety of applied research fields, from biotechnology and the environmental sciences to fundamental chemistry and physics. Apart from useful catalytic properties, silver clusters (Ag n , n < 10) were recently shown to also exhibit exceptional optical properties. The optical properties and performance of Ag-CLs offer strong potential for their integration into appealing micro(nano)-optoelectronic devices. To date, however, the rational design and directed synthesis of Ag-CLs with specific functionalities has remained elusive. The inability for rational design stems mainly from a lack of understanding of their novel atomic-scale phenomena. This is because accurately studying silver cluster systems at such a scale is hindered by the perturbations introduced during exposure to various experimental probes. For instance, silver possesses a strong tendency to cluster and form ever-larger Ag aggregates while probed with high-energy electron beams and X-ray irradiation. As well, there exists a need to provide a stabilizing environment for which Ag n δ+ clusters can persist, setting up a complex interacting guest-host system, as isolated silver clusters are confined within a suitable hosting medium. Fundamental research into Ag n δ+ formation mechanisms and their important optical properties is paramount to establishing truly informed synthesis protocols. Over recent years, we have developed several protocols for the ship-in-a-bottle synthesis of highly luminescent Ag-CLs within the microporous interiors of zeolite frameworks. This approach has yielded materials displaying a wide variety of optical properties, offering a spectrum of possible applications, from nano(micro)photonic devices to smart luminescent labels and sensors. The versatility of the Ag-zeolite multicomponent system is directly related to the intrinsic and complex tunability of the system as a whole. There are several key zeolite parameters that confer properties to the clusters, namely, the framework Si/Al ratio, choice of counterbalancing ions, silver loading, and zeolite topology, and cannot be overlooked. This Account is intended to shed light on the current state-of-the-art of luminescent Ag-CLs confined in zeolitic matrices, emphasizing the use of combinatorial approaches to overcome problems associated with the correct characterization and correlation of their structural, electronic, and photoluminescence properties, all to establish the important design principles for developing functional silver-zeolite-based materials. Additionally, examples of emerging applications and future perspectives for functional luminescent Ag-zeolite materials are addressed in this Account.

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.

Spectroscopic investigations of humic-like acids formed via polycondensation reactions between glycine, catechol and glucose in the presence of natural zeolites

NASA Astrophysics Data System (ADS)

Fukuchi, Shigeki; Miura, Akitaka; Okabe, Ryo; Fukushima, Masami; Sasaki, Masahide; Sato, Tsutomu

2010-10-01

Polycondensation reactions between low-molecular-weight compounds, such as amino acids, sugars and phenols, are crucially important processes in the formation of humic substances, and clay minerals have the ability to catalyze these reactions. In the present study, catechol (CT), glycine (Gly) and glucose (Gl) were used as representative phenols, amino acids and sugars, respectively, and the effects of the catalytic activities of natural zeolites on polycondensation reactions between these compounds were investigated. The extent of polycondensation was evaluated by measuring the specific absorbance at 600 nm ( E600) as an index of the degree of darkening. After a 3-week incubation period, the E600 values for solutions that contained zeolite samples were 4-10 times greater than those measured in the absence of zeolite, suggesting that the zeolite had, in fact, catalyzed the polycondensation reaction. The humic-like acids (HLAs) produced in the reactions were isolated, and their elemental composition and molecular weights determined. When formed in the presence of a zeolite, the nitrogen contents and molecular weights for the HLAs were significantly higher, compared to the HLA sample formed in the absence of zeolite. In addition, solid-state CP-MAS 13C NMR spectra and carboxylic group analyses of the HLA samples indicated that the concentration of carbonyl carbon species for quinones and ketones produced in the presence of zeolite were higher than the corresponding values for samples produced in the absence of a zeolite. Carbonyl carbons in quinones and ketones indicate the nucleophilic characteristics of the samples. Therefore, a nitrogen atom in Gly, which serves as nucleophile, is incorporated into quinones and ketones in CT and Gl. The differences in the catalytic activities of the zeolite samples can be attributed to differences in their transition metal content (Fe, Mn and Ti), which function as Lewis acids.

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.

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.

Silylated Zeolites With Enhanced Hydrothermal Stability for the Aqueous-Phase Hydrogenation of Levulinic Acid to γ-Valerolactone

PubMed Central

Vu, Hue-Tong; Harth, Florian M.; Wilde, Nicole

2018-01-01

A systematic silylation approach using mono-, di-, and trichlorosilanes with different alkyl chain lengths was employed to enhance the hydrothermal stability of zeolite Y. DRIFT spectra of the silylated zeolites indicate that the attachment of the silanes takes place at surface silanol groups. Regarding hydrothermal stability under aqueous-phase processing (APP) conditions, i.e., pH ≈ 2, 473 K and autogenous pressure, the selective silylation of the zeolite surface using monochlorosilanes has no considerable influence. By using trichlorosilanes, the hydrothermal stability of zeolite Y can be improved significantly as proven by a stability test in an aqueous solution of 0.2 M levulinic acid (LA) and 0.6 M formic acid (FA) at 473 K. However, the silylation with trichlorosilanes results in a significant loss of total specific pore volume and total specific surface area, e.g., 0.35 cm3 g−1 and 507 m2 g−1 for the silylated zeolite Y functionalized with n-octadecyltrichlorosilane compared to 0.51 cm3 g−1 and 788 m2 g−1 for the parent zeolite Y. The hydrogenation of LA to γ-valerolactone (GVL) was conducted over 3 wt.-% Pt on zeolite Y (3PtY) silylated with either n-octadecyltrichlorosilane or methyltrichlorosilane using different reducing agents, e.g., FA or H2. While in the stability test an enhanced hydrothermal stability was found for zeolite Y silylated with n-octadecyltrichlorosilane, its stability in the hydrogenation of LA was far less pronounced. Only by applying an excess amount of methyltrichlorosilane, i.e., 10 mmol per 1 g of zeolite Y, presumably resulting in a high degree of polymerization among the silanes, a recognizable improvement of the stability of the 3 PtY catalyst could be achieved. Nonetheless, the pore blockage found for zeolite Y silylated with an excess amount of methyltrichlorosilane was reflected in a drastically lower GVL yield at 493 K using FA as reducing agent, i.e., 12 vs. 34% for 3PtY after 24 h. PMID:29868552

Silylated Zeolites with Enhanced Hydrothermal Stability for the Aqueous-Phase Hydrogenation of Levulinic Acid to γ-Valerolactone

NASA Astrophysics Data System (ADS)

Vu, Hue-Tong; Harth, Florian M.; Wilde, Nicole

2018-05-01

A systematic silylation approach using mono-, di- and trichlorosilanes with different alkyl chain lengths was employed to enhance the hydrothermal stability of zeolite Y. DRIFT spectra of the silylated zeolites indicate that the attachment of the silanes takes place at surface silanol groups. Regarding hydrothermal stability under aqueous-phase processing conditions, i.e., pH ≈ 2, 473 K and autogenous pressure, the selective silylation of the zeolite surface using monochlorosilanes has no considerable influence. By using trichlorosilanes, the hydrothermal stability of zeolite Y can be improved significantly as proven by a stability test in an aqueous solution of 0.6 M levulinic acid (LA) and 0.2 M formic acid (FA) at 473 K. However, the silylation with trichlorosilanes results in a significant loss of total specific pore volume and total specific surface area, e.g., 0.35 cm3 g-1 and 507 m2 g 1 for the silylated zeolite Y functionalized with n octadecyltrichlorosilane compared to 0.51 cm3 g 1 and 788 m2 g-1 for the parent zeolite Y. The hydrogenation of LA to γ valerolactone (GVL) was conducted over 3 wt.-% Pt on zeolite Y (3PtY) silylated with either n octadecyltrichlorosilane or methyltrichlorosilane using different reducing agents, e.g., FA or H2. While in the stability test an enhanced hydrothermal stability was found for zeolite Y silylated with n octadecyltrichlorosilane, its stability in the hydrogenation of LA was far less pronounced. Only by applying an excess amount of methyltrichlorosilane, i.e., 10 mmol per 1 g of zeolite Y, presumably resulting in a high degree of polymerization among the silanes, a recognizable improvement of the stability of the 3 PtY catalyst could be achieved. Nonetheless, the pore blockage found for zeolite Y silylated with an excess amount of methyltrichlorosilane was reflected in a drastically lower GVL yield at 493 K using FA as reducing agent, i.e., 12% vs. 34% for 3PtY after 24 h.

Wire-Mesh-Based Sorber for Removing Contaminants from Air

NASA Technical Reports Server (NTRS)

Perry, Jay; Roychoudhury, Subir; Walsh, Dennis

2006-01-01

A paper discusses an experimental regenerable sorber for removing CO2 and trace components principally, volatile organic compounds, halocarbons, and NH3 from spacecraft cabin air. This regenerable sorber is a prototype of what is intended to be a lightweight alternative to activated-carbon and zeolite-pellet sorbent beds now in use. The regenerable sorber consists mainly of an assembly of commercially available meshes that have been coated with a specially-formulated washcoat containing zeolites. The zeolites act as the sorbents while the meshes support the zeolite-containing washcoat in a configuration that affords highly effective surface area for exposing the sorbents to flowing air. The meshes also define flow paths characterized by short channel lengths to prevent excessive buildup of flow boundary layers. Flow boundary layer resistance is undesired because it can impede mass and heat transfer. The total weight and volume comparison versus the atmosphere revitalization equipment used onboard the International Space Station for CO2 and trace-component removal will depend upon the design details of the final embodiment. However, the integrated mesh-based CO2 and trace-contaminant removal system is expected to provide overall weight and volume savings by eliminating most of the trace-contaminant control equipment presently used in parallel processing schemes traditionally used for spacecraft. The mesh-based sorbent media enables integrating the two processes within a compact package. For the purpose of regeneration, the sorber can be heated by passing electric currents through the metallic meshes combined with exposure to space vacuum. The minimal thermal mass of the meshes offers the potential for reduced regeneration-power requirements and cycle time required for regeneration compared to regenerable sorption processes now in use.

Sorption of chlorophenols on microporous minerals: mechanism and influence of metal cations, solution pH, and humic acid.

PubMed

Yang, Hui; Hu, Yuanan; Cheng, Hefa

2016-10-01

Sorption of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) on a range of dealuminated zeolites were investigated to understand the mechanism of their sorption on microporous minerals, while the influence of common metal cations, solution pH, and humic acid was also studied. Sorption of chlorophenols was found to increase with the hydrophobicity of the sorbates and that of the microporous minerals, indicating the important role of hydrophobic interactions, while sorption was also stronger in the micropores of narrower sizes because of greater enhancement of the dispersion interactions. The presence of metal cations could enhance chlorophenol sorption due to the additional electrostatic attraction between metal cations exchanged into the mineral micropores and the chlorophenolates, and this effect was apparent on the mineral sorbent with a high density of surface cations (2.62 sites/nm(2)) in its micropores. Under circum-neutral or acidic conditions, neutral chlorophenol molecules adsorbed into the hydrophobic micropores through displacing the "loosely bound" water molecules, while their sorption was negligible under moderately alkaline conditions due to electrostatic repulsion between the negatively charged zeolite framework and anionic chlorophenolates. The influence of humic acid on sorption of chlorophenols on dealuminated Y zeolites suggests that its molecules did not block the micropores but created a secondary sorption sites by forming a "coating layer" on the external surface of the zeolites. These mechanistic insights could help better understand the interactions of ionizable chlorophenols and metal cations in mineral micropores and guide the selection and design of reusable microporous mineral sorbents for sorptive removal of chlorophenols from aqueous stream.

Substrate- and plant-mediated removal of citrate-coated silver nanoparticles in constructed wetlands.

PubMed

Auvinen, Hannele; Sepúlveda, Viviana Vásquez; Rousseau, Diederik P L; Du Laing, Gijs

2016-11-01

The growing production and commercial application of engineered nanoparticles (ENPs), such as Ag, CeO 2 , and TiO 2 nanoparticles, induce a risk to the environment as ENPs are released during their use. The comprehensive assessment of the environmental risk that the ENPs pose involves understanding their fate and behavior in wastewater treatment systems. Therefore, in this study, we investigate the effect of plants and different substrates on the retention and distribution of citrate-coated silver nanoparticles (Ag-NPs) in batch experimental setups simulating constructed wetlands (CWs). Sand, zeolite, and biofilm-coated gravel induce efficient removal (85, 55, and 67 %, respectively) of Ag from the water phase indicating that citrate-coated Ag-NPs are efficiently retained in CWs. Plants are a minor factor in retaining Ag as a large fraction of the recovered Ag remains in the water phase (0.42-0.58). Most Ag associated with the plant tissues is attached to or taken up by the roots, and only negligible amounts (maximum 3 %) of Ag are translocated to the leaves under the applied experimental conditions.

Preparation, Processing, and Characterization of Oriented Polycrystalline Zeolite and Aluminophosphate Membranes

NASA Astrophysics Data System (ADS)

Stoeger, Jared Andrew

Since the advent of zeolite membranes, speculation on their industrial applicability has been closely monitored, although widespread commercialization has been hampered by limitations in fabrication and post-synthesis processing. Economical, energy-efficient technology breakthroughs require an evaluation of a range of material candidates which show robustness and reliability. Straightforward manufacturing techniques should be devised to generate thousands of square meters of membrane area; however, this demands control of structural characteristics on the scale of nanometers. As described in this dissertation, the path forward will be forged by exploiting the intrinsic crystalline properties of zeolites or aluminophosphates for the next advancement in membrane technology. A facile method is described for the preparation of silicalite-1 (MFI zeolite type) membranes using the secondary growth technique on symmetric porous stainless steel tubes. Activation through rapid thermal processing (RTP), a lamp-based heat-treatment process used as a critical fabrication step in silicon integrated circuit manufacturing, is proven to reduce the density of non-zeolitic transport pathways which are detrimental to high-resolution molecular sieving. RTP-treated membranes are shown to have enhanced performance in the binary separation of vapor-phase isomers (p-/o-xylene), gas-phase isomers (n-/i-butane), and alcohol/water when compared to membranes activated at a much slower heating rate but otherwise similarly-prepared. The performance is discussed in the context of the market potential for industrially-attractive separations: the recovery of p-xylene from an isomeric mixture or alcohol biofuels from aqueous post-fermentation streams. Hydrothermal growth techniques for the preparation and characterization of continuous aluminophosphate (AFI zeolite type) membranes with a preferential crystallographic alignment on porous alpha-Al2O3 disc supports are demonstrated. A mechanism is proposed for flake-like crystal formation in the early stages of in-plane crystalline intergrowth between oriented columnar crystals by electric heating. It is shown that elevated temperatures induce a phase transformation to a densified aluminophosphate phase despite framework metal substitution or alternative heat-treatment conditions. Additionally, stability and membrane characteristics following in situ microwave growth using a TiO2-coated support are examined. Indications of improved quality validate the candidacy of the microwave-grown membranes with regard to the potential for carbon nanotube synthesis in the aligned one-dimensional channels for high flux, high separation factor membrane fabrication.

Ultra-small Ag clusters in zeolite A4: Antibacterial and thermochromic applications

NASA Astrophysics Data System (ADS)

Horta-Fraijo, P.; Cortez-Valadez, M.; Flores-Lopez, N. S.; Britto Hurtado, R.; Vargas-Ortiz, R. A.; Perez-Rodriguez, A.; Flores-Acosta, M.

2018-03-01

The physical and chemical properties of metal clusters depend on their atomic structure, therefore, it is important to determine the lowest-energy structures of the clusters in order to understand and utilize their properties. In this work, we use the Density Functional Theory (DFT) at the generalized gradient approximation level Becke's three-parameter and the gradient corrected functional of Lee, Yang and Puar (B3LYP) in combination with the basis set LANL2DZ (the effective core potentials and associated double-zeta valence) to determine some of the structural, electronic and vibrational properties of the planar silver clusters (Agn clusters n = 2-24). Additionally, the study reports the experimental synthesis of small silver clusters in synthetic zeolite A4. The synthesis was possible using the ion exchange method with some precursors like silver nitrate (AgNO3) and synthetic zeolite A4. The silver clusters in zeolite powder underwent thermal treatment at 450 °C to release the remaining water or humidity on it. The morphology of the particles was determined by Transmission Electron microscopy. The nanomaterials obtained show thermochromic properties. The structural parameters were correlated theoretically and experimentally.

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 improvement of gas-sensing properties of SnO2/zeolite-assembled composite

NASA Astrophysics Data System (ADS)

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

2018-05-01

SnO2-impregnated zeolite composites were used as gas-sensing materials to improve the sensitivity and selectivity of the metal oxide-based resistive-type gas sensors. Nanocrystalline MFI type zeolite (ZSM-5) was prepared by hydrothermal synthesis. Highly dispersive SnO2 nanoparticles were then successfully assembled on the surface of the ZSM-5 nanoparticles by using the impregnation methods. The SnO2 nanoparticles are nearly spherical with the particle size of 10 nm. An enhanced formaldehyde sensing of as-synthesized SnO2-ZSM-5-based sensor was observed whereas a suppression on the sensor response to other volatile organic vapors (VOCs) such as acetone, ethanol, and methanol was noticed. The possible reasons for this contrary observation were proposed to be related to the amount of the produced water vapor during the sensing reactions assisted by the ZSM-5 nanoparticles. This provides a possible new strategy to improve the selectivity of the gas sensors. The effect of the humidity on the sensor response to formaldehyde was investigated and it was found the higher humidity would decrease the sensor response. A coating layer of the ZSM-5 nanoparticles on top of the SnO2-ZSM-5-sensing film was thus applied to further improve the sensitivity and selectivity of the sensor through the strong adsorption ability to polar gases and the "filtering effect" by the pores of ZSM-5.

Structural characterization of a non-heme iron active site in zeolites that hydroxylates methane

DOE PAGES

Snyder, Benjamin E. R.; Bottger, Lars H.; Bols, Max L.; ...

2018-04-02

Iron-containing zeolites exhibit unprecedented reactivity in the low-temperature hydroxylation of methane to form methanol. Reactivity occurs at a mononuclear ferrous active site, α-Fe(II), that is activated by N 2O to form the reactive intermediate α-O. This has been defined as an Fe(IV)=O species. Using nuclear resonance vibrational spectroscopy coupled to X-ray absorption spectroscopy, we probe the bonding interaction between the iron center, its zeolite lattice-derived ligands, and the reactive oxygen. α-O is found to contain an unusually strong Fe(IV)=O bond resulting from a constrained coordination geometry enforced by the zeolite lattice. As a result, density functional theory calculations clarify howmore » the experimentally determined geometric structure of the active site leads to an electronic structure that is highly activated to perform H-atom abstraction.« less

Structural characterization of a non-heme iron active site in zeolites that hydroxylates methane

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

Snyder, Benjamin E. R.; Bottger, Lars H.; Bols, Max L.

Iron-containing zeolites exhibit unprecedented reactivity in the low-temperature hydroxylation of methane to form methanol. Reactivity occurs at a mononuclear ferrous active site, α-Fe(II), that is activated by N 2O to form the reactive intermediate α-O. This has been defined as an Fe(IV)=O species. Using nuclear resonance vibrational spectroscopy coupled to X-ray absorption spectroscopy, we probe the bonding interaction between the iron center, its zeolite lattice-derived ligands, and the reactive oxygen. α-O is found to contain an unusually strong Fe(IV)=O bond resulting from a constrained coordination geometry enforced by the zeolite lattice. As a result, density functional theory calculations clarify howmore » the experimentally determined geometric structure of the active site leads to an electronic structure that is highly activated to perform H-atom abstraction.« less

Positron annihilation lifetime spectroscopy (PALS) study of the as prepared and calcined MFI zeolites

NASA Astrophysics Data System (ADS)

Bosnar, Sanja; Vrankić, Martina; Bosnar, Damir; Ren, Nan; Šarić, Ankica

2017-11-01

The synthesis of high silica zeolites in many cases implies the usage of organic structural direction agents (SDA). However, to manifest their functionalities, the SDA occluded inside the channels of the as-synthesized structure should be removed, usually by a high temperature treatment (calcination). In this paper, the positron annihilation lifetime spectroscopy (PALS) was used to monitor the development of accessible spaces, their sizes and distributions in MFI zeolites, ZSM-5 and silicalite-1 in order to give an additional insight in the process of the SDA removal. For that purpose, a conventional PALS setup with 22Na positron source was applied. It was established that there is a pronounced difference between positron annihilation data for these two zeolites of the same structural type. The samples were additionally analysed by X-ray powder diffraction at room temperature with a crystal structure refinement and thermogravimetry.

Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks

NASA Astrophysics Data System (ADS)

Kim, Hyunho; Cho, H. Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M.; Wang, Evelyn N.

2016-01-01

Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes.

Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks

PubMed Central

Kim, Hyunho; Cho, H. Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M.; Wang, Evelyn N.

2016-01-01

Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes. PMID:26796523

Selective anaerobic oxidation of methane enables direct synthesis of methanol.

PubMed

Sushkevich, Vitaly L; Palagin, Dennis; Ranocchiari, Marco; van Bokhoven, Jeroen A

2017-05-05

Direct functionalization of methane in natural gas remains a key challenge. We present a direct stepwise method for converting methane into methanol with high selectivity (~97%) over a copper-containing zeolite, based on partial oxidation with water. The activation in helium at 673 kelvin (K), followed by consecutive catalyst exposures to 7 bars of methane and then water at 473 K, consistently produced 0.204 mole of CH 3 OH per mole of copper in zeolite. Isotopic labeling confirmed water as the source of oxygen to regenerate the zeolite active centers and renders methanol desorption energetically favorable. On the basis of in situ x-ray absorption spectroscopy, infrared spectroscopy, and density functional theory calculations, we propose a mechanism involving methane oxidation at Cu II oxide active centers, followed by Cu I reoxidation by water with concurrent formation of hydrogen. Copyright © 2017, American Association for the Advancement of Science.

Combined PDF and Rietveld studies of ADORable zeolites and the disordered intermediate IPC-1P.

PubMed

Morris, Samuel A; Wheatley, Paul S; Položij, Miroslav; Nachtigall, Petr; Eliášová, Pavla; Čejka, Jiří; Lucas, Tim C; Hriljac, Joseph A; Pinar, Ana B; Morris, Russell E

2016-09-28

The disordered intermediate of the ADORable zeolite UTL has been structurally confirmed using the pair distribution function (PDF) technique. The intermediate, IPC-1P, is a disordered layered compound formed by the hydrolysis of UTL in 0.1 M hydrochloric acid solution. Its structure is unsolvable by traditional X-ray diffraction techniques. The PDF technique was first benchmarked against high-quality synchrotron Rietveld refinements of IPC-2 (OKO) and IPC-4 (PCR) - two end products of IPC-1P condensation that share very similar structural features. An IPC-1P starting model derived from density functional theory was used for the PDF refinement, which yielded a final fit of Rw = 18% and a geometrically reasonable structure. This confirms the layers do stay intact throughout the ADOR process and shows PDF is a viable technique for layered zeolite structure determination.

Zeolite-based hemostat QuikClot releases calcium into blood and promotes blood coagulation in vitro

PubMed Central

Li, Jing; Cao, Wei; Lv, Xiao-xing; Jiang, Li; Li, Yue-jun; Li, Wang-zhou; Chen, Shao-zong; Li, Xue-yong

2013-01-01

Aim: To examine the changes in electrolyte concentrations after addition of zeolite-based hemostat QuikClot in blood and the effects of zeolite on blood coagulation in vitro. Methods: Fresh blood was taken from healthy adult volunteers and sheep, and the electrolyte concentrations in blood were measured using a blood electrolyte analyzer. Zeolite Saline Solution (ZSS) was prepared by addition of 2 g zeolite to 0.9% NaCl solution (4, 8, or 16 mL). The electrolytes in ZSS were measured using inductively coupled plasma atomic emission spectroscopy. The prothrombin time (PT) and activated partial thromboplastin time (APTT) of blood were measured using the test tube method. The activated clotting time (ACT) and clotting rate (CR) of blood were measured with Sonoclot Coagulation and Platelet Function Analyzer. Results: Addition of zeolite (50 and 100 mg) in 2 mL human blood significantly increased Ca2+ concentration, while Na+ and K+ concentrations were significantly decreased. Addition of zeolite (50 and 100 mg) in 0.9% NaCl solution (2 mL) caused similar changes in Ca2+ and Na+ concentrations. Si4+ (0.2434 g/L) and Al3+ (0.2575 g/L) were detected in ZSS (2 g/8 mL). Addition of ZSS in sheep blood shortened APTT in a concentration dependent manner, without changing PT. ZSS or aqueous solution of CaCl2 that contained Ca2+ concentration identical to that of ZSS significantly shortened ACT in human blood without significantly changing CR, and the effect of ZSS on ACT was not significantly different from that of CaCl2. Conclusion: Zeolite releases Ca2+ into blood, thus accelerating the intrinsic pathway of blood coagulation and shortening the clot formation time. PMID:23334236

Zeolite-based hemostat QuikClot releases calcium into blood and promotes blood coagulation in vitro.

PubMed

Li, Jing; Cao, Wei; Lv, Xiao-xing; Jiang, Li; Li, Yue-jun; Li, Wang-zhou; Chen, Shao-zong; Li, Xue-yong

2013-03-01

To examine the changes in electrolyte concentrations after addition of zeolite-based hemostat QuikClot in blood and the effects of zeolite on blood coagulation in vitro. Fresh blood was taken from healthy adult volunteers and sheep, and the electrolyte concentrations in blood were measured using a blood electrolyte analyzer. Zeolite Saline Solution (ZSS) was prepared by addition of 2 g zeolite to 0.9% NaCl solution (4, 8, or 16 mL). The electrolytes in ZSS were measured using inductively coupled plasma atomic emission spectroscopy. The prothrombin time (PT) and activated partial thromboplastin time (APTT) of blood were measured using the test tube method. The activated clotting time (ACT) and clotting rate (CR) of blood were measured with Sonoclot Coagulation and Platelet Function Analyzer. Addition of zeolite (50 and 100 mg) in 2 mL human blood significantly increased Ca(2+) concentration, while Na(+) and K(+) concentrations were significantly decreased. Addition of zeolite (50 and 100 mg) in 0.9% NaCl solution (2 mL) caused similar changes in Ca(2+) and Na(+) concentrations. Si(4+) (0.2434 g/L) and Al(3+) (0.2575 g/L) were detected in ZSS (2 g/8 mL). Addition of ZSS in sheep blood shortened APTT in a concentration dependent manner, without changing PT. ZSS or aqueous solution of CaCl2 that contained Ca(2+) concentration identical to that of ZSS significantly shortened ACT in human blood without significantly changing CR, and the effect of ZSS on ACT was not significantly different from that of CaCl2. Zeolite releases Ca(2+) into blood, thus accelerating the intrinsic pathway of blood coagulation and shortening the clot formation time.

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.

Interplay of bonding and geometry of the adsorption complexes of light alkanes within cationic faujasites. Combined spectroscopic and computational study.

PubMed

Pidko, Evgeny A; Xu, Jiang; Mojet, Barbara L; Lefferts, Leon; Subbotina, Irina R; Kazansky, Vladimir B; van Santen, Rutger A

2006-11-16

A FT-IR spectroscopic study of methane, ethane, and propane adsorption on magnesium and calcium forms of zeolite Y reveals different vibrational properties of the adsorbed molecules depending on the exchanged cation. This is attributed to different adsorption conformations of the hydrocarbons. Two-fold eta(2) coordination of light alkanes is realized for MgY, whereas in case of CaY zeolite quite different adsorption modes are found, involving more C-H bonds in the interaction with the cation. The topological analysis of the electron density distribution function of the adsorption complexes shows that when a hydrocarbon coordinates to the exchanged Mg(2+) ions, van der Waals bonds between H atoms of the alkane and basic zeolitic oxygens significantly contribute to the overall adsorption energy, whereas in case of CaY zeolite such interactions play only an indirect role. It is found that, due to the much smaller ionic radius of the Mg(2+) ion as compared to that of Ca(2+), the former ions are significantly shielded with the surrounding oxygens of the zeolitic cation site. This results in a small electrostatic contribution to the stabilization of the adsorbed molecules. In contrast, for CaY zeolite the stabilization of alkanes in the electrostatic field of the partially shielded Ca(2+) cation significantly contributes to the adsorption energy. This is in agreement with the experimentally observed lower overall absorption of C-H stretching vibrations of alkanes loaded to MgY as compared to those for CaY zeolite. The preferred conformation of the adsorbed alkanes is controlled by the bonding within the adsorption complexes that, in turn, strongly depends on the size and location of the cations in the zeolite cavity.

Simultaneous removal of aqueous Zn2+, Cu2+, Cd2+, and Pb2+ by zeolites synthesized from low-calcium and high-calcium fly ash.

PubMed

Ji, X D; Ma, Y Y; Peng, S H; Gong, Y Y; Zhang, F

2017-10-01

In this study, zeolites were synthesized from low-calcium (LCZ) and high-calcium (HCZ) fly ash, respectively. Subsequently, the zeolites were tested for their removal effectiveness for four aqueous cations, namely, Zn 2+ , Cu 2+ , Cd 2+ , and Pb 2+ , as a function of contact time, pH value, adsorbent dosage, and initial concentration of heavy metals. Both zeolites were characterized by X-ray diffraction, X-ray fluorescence spectrometry, scanning electron microscopy, specific surface area, and cation exchange capacity. The results show that HCZ mainly consists of an unnamed zeolite (Na 6 [AlSiO 4 ] 6 ·4H 2 O), whereas LCZ mainly consists of faujasite-type zeolite. The optimum sorption conditions were pH = 6.0; adsorbent dosage = 1.0 g·L -1 ; temperature = 25 °C; contact time = 100 min; and initial heavy metal concentration = 100 mg·L -1 . The sorption kinetics of the four aqueous cations on both LCZ and HCZ followed the pseudo-second-order kinetic model, and the sorption isotherm data fitted well with the Langmuir isotherm model. For LCZ, the maximum adsorption capacities of Zn 2+ , Cu 2+ , Cd 2+ , and Pb 2+ were 155.76, 197.86, 123.76, and 186.22 mg·g -1 , respectively. For HCZ, the values were 154.08, 183.15, 118.91, and 191.94 mg·g -1 , respectively. The zeolites were regenerated by NaCl solution (1 mol·L -1 ) and showed high removal efficiency. In conclusion, zeolites produced by fly ash are promising materials for removing Zn 2+ , Cu 2+ , Cd 2+ , and Pb 2+ from wastewater.

From average to local structure: a Rietveld and an atomic pair distribution function (PDF) study of selenium clusters in zeolite-NdY.

PubMed

Abeykoon, A M Milinda; Donner, Wolfgang; Brunelli, Michela; Castro-Colin, Miguel; Jacobson, Allan J; Moss, Simon C

2009-09-23

The structure of Se particles in the approximately 13 A diameter alpha-cages of zeolite NdY has been determined by Rietveld refinement and pair distribution function (PDF) analysis of X-ray data. With the diffuse scattering subtracted an average structure comprised of an undistorted framework containing nanoclusters of 20 Se atoms is observed. The intracluster correlations and the cluster-framework correlations which give rise to diffuse scattering were modeled by using PDF analysis.

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 oxygen sites (rather than one), and formation of a new supercell. New calorimetric measurements of enthalpy are used to examine the energetics of the hydrosodalite family of zeolites---specifically, formation enthalpies and hydration energies. Finally, force-field computational methods begin the examination of water in terms of energetics, structure, and radionuclide containment and diffusion.

The use of zeolites to generate PET phantoms for the validation of quantification strategies in oncology.

PubMed

Zito, Felicia; De Bernardi, Elisabetta; Soffientini, Chiara; Canzi, Cristina; Casati, Rosangela; Gerundini, Paolo; Baselli, Giuseppe

2012-09-01

In recent years, segmentation algorithms and activity quantification methods have been proposed for oncological (18)F-fluorodeoxyglucose (FDG) PET. A full assessment of these algorithms, necessary for a clinical transfer, requires a validation on data sets provided with a reliable ground truth as to the imaged activity distribution, which must be as realistic as possible. The aim of this work is to propose a strategy to simulate lesions of uniform uptake and irregular shape in an anthropomorphic phantom, with the possibility to easily obtain a ground truth as to lesion activity and borders. Lesions were simulated with samples of clinoptilolite, a family of natural zeolites of irregular shape, able to absorb aqueous solutions of (18)F-FDG, available in a wide size range, and nontoxic. Zeolites were soaked in solutions of (18)F-FDG for increasing times up to 120 min and their absorptive properties were characterized as function of soaking duration, solution concentration, and zeolite dry weight. Saturated zeolites were wrapped in Parafilm, positioned inside an Alderson thorax-abdomen phantom and imaged with a PET-CT scanner. The ground truth for the activity distribution of each zeolite was obtained by segmenting high-resolution finely aligned CT images, on the basis of independently obtained volume measurements. The fine alignment between CT and PET was validated by comparing the CT-derived ground truth to a set of zeolites' PET threshold segmentations in terms of Dice index and volume error. The soaking time necessary to achieve saturation increases with zeolite dry weight, with a maximum of about 90 min for the largest sample. At saturation, a linear dependence of the uptake normalized to the solution concentration on zeolite dry weight (R(2) = 0.988), as well as a uniform distribution of the activity over the entire zeolite volume from PET imaging were demonstrated. These findings indicate that the (18)F-FDG solution is able to saturate the zeolite pores and that the concentration does not influence the distribution uniformity of both solution and solute, at least at the trace concentrations used for zeolite activation. An additional proof of uniformity of zeolite saturation was obtained observing a correspondence between uptake and adsorbed volume of solution, corresponding to about 27.8% of zeolite volume. As to the ground truth for zeolites positioned inside the phantom, the segmentation of finely aligned CT images provided reliable borders, as demonstrated by a mean absolute volume error of 2.8% with respect to the PET threshold segmentation corresponding to the maximum Dice. The proposed methodology allowed obtaining an experimental phantom data set that can be used as a feasible tool to test and validate quantification and segmentation algorithms for PET in oncology. The phantom is currently under consideration for being included in a benchmark designed by AAPM TG211, which will be available to the community to evaluate PET automatic segmentation methods.

Fabrication of ZIF-8@SiO2 Micro/Nano Hierarchical Superhydrophobic Surface on AZ31 Magnesium Alloy with Impressive Corrosion Resistance and Abrasion Resistance.

PubMed

Wu, Cuiqing; Liu, Qi; Chen, Rongrong; Liu, Jingyuan; Zhang, Hongsen; Li, Rumin; Takahashi, Kazunobu; Liu, Peili; Wang, Jun

2017-03-29

Superhydrophobic coatings are highly promising for protecting material surfaces and for wide applications. In this study, superhydrophobic composites, comprising a rhombic-dodecahedral zeolitic imidazolate framework (ZIF-8@SiO 2 ), have been manufactured onto AZ31 magnesium alloy via chemical etching and dip-coating methods to enhance stability and corrosion resistance. Herein, we report on a simple strategy to modify hydrophobic hexadecyltrimethoxysilan (HDTMS) on ZIF-8@SiO 2 to significantly improve the property of repelling water. We show that various liquids can be stable on its surface and maintain a contact angle higher than 150°. The morphologies and chemical composition were characterized by means of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FI-IR). In addition, the anticorrosion and antiattrition properties of the film were assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization and HT, respectively. Such a coating shows promising potential as a material for large-scale fabrication.

Effect of humic acid preloading on phosphate adsorption onto zirconium-modified zeolite.

PubMed

Lin, Jianwei; Zhang, Zhe; Zhan, Yanhui

2017-05-01

A zirconium-modified zeolite (ZrMZ) was prepared, and then, humic acid (HA) was immobilized on the ZrMZ surface to prepare HA-loaded ZrMZ (HA-ZrMZ). The obtained ZrMZ and HA-ZrMZ were characterized by energy dispersive X-ray spectroscopy, elemental analyzer, N 2 adsorption/desorption isotherms, pH at the point of zero charge, and X-ray photoelectron spectroscopy. The adsorption characteristics of phosphate on ZrMZ and HA-ZrMZ were comparatively investigated in batch mode. The adsorption mechanism of phosphate on ZrMZ and HA-ZrMZ was investigated by ionic strength effect and 31 P nuclear magnetic resonance. The mechanism for phosphate adsorption onto ZrMZ was the formation of inner-sphere phosphate complexes at the solid/solution interface. The preloading of HA on ZrMZ reduced the phosphate adsorption capacity, and the more the HA loading amount, the lower the phosphate adsorption capacity. However, the preloading of HA on ZrMZ did not change the phosphate adsorption mechanism; i.e., the formation of inner-sphere phosphate surface complexes was still responsible for the adsorption of phosphate on HA-ZrMZ. The decreased phosphate adsorption capacity for ZrMZ after HA coating could be attributed to the fact that the coating of HA on ZrMZ reduced the amount of binding active sites available for phosphate adsorption, changed the adsorbent surface charges, and reduced the specific surface areas and pore volumes of ZrMZ.

Biosensors Based on Urease Adsorbed on Nickel, Platinum, and Gold Conductometric Transducers Modified with Silicalite and Nanozeolites

NASA Astrophysics Data System (ADS)

Kucherenko, Ivan S.; Soldatkin, Oleksandr O.; Kasap, Berna Ozansoy; Kurç, Burcu Akata; Melnyk, Volodymir G.; Semenycheva, Lyudmila M.; Dzyadevych, Sergei V.; Soldatkin, Alexei P.

This work describes urease-based conductometric biosensors that were created using nontypical method of urease immobilization via adsorption on micro- and nanoporous particles: silicalite and nanocrystalline zeolites Beta (BEA) and L. Conductometric transducers with nickel, gold, and platinum interdigitated electrodes were used. Active regions of the nickel transducers were modified with microparticles using two procedures—spin coating and drop coating. Gold and platinum transducers were modified with silicalite using drop coating since it was more effective. Scanning electron microscopy was used to evaluate effectiveness of these procedures. The procedure of spin coating produced more uniform layers of particles (and biosensors had good reproducibility of preparation), but it was more complicated, drop coating was easier and led to formation of a bulk of particles; thus, biosensors had bigger sensitivity but worse reproducibility of preparation. Urease was immobilized onto transducers modified with particles by physical adsorption. Analytical characteristics of the obtained biosensors for determination of urea (calibration curves, sensitivity, limit of detection, linear concentration range, noise of responses, reproducibility of signal during a day, and operational stability during 3 days) were compared. Biosensors with all three particles deposited by spin coating showed similar characteristics; however, silicalite was a bit more effective. Biosensors based on nickel transducers modified by drop coating had better characteristics in comparison with modification by spin coating (except reproducibility of preparation). Transducers with gold electrodes showed best characteristics while creating biosensors, platinum electrodes were slightly inferior to them, and nickel electrodes were the worst.

Inhibition of foodborne bacteria by antibacterial coatings printed onto food packaging films.

PubMed

Widsten, P; Mesic, B B; Cruz, C D; Fletcher, G C; Chycka, M A

2017-07-01

Films containing antibacterial compounds could be used for packaging perishable foods such as fresh fish and meat for sea freighting over long distances. However, existing commercialised options (films with nanosilver zeolites or wasabi extract) are only permitted for food contact in certain regions and films containing alternative antibacterial ingredients are required e.g. for exports to Europe. Certain non-volatile phenolic plant extracts have shown promising antibacterial activity against a wide range of foodborne bacteria in in vitro assays and when integrated in coatings for perishable foods such as fish and meat. Extracts rich in gallotannins tend to show stronger antibacterial effects than other phenols such as flavonoids. Such extracts could be coated onto commercial barrier films by means of flexographic printing-a more industrially feasible option than rod coating or solvent casting typically used in antibacterial coating research. The goal of the present work was to investigate the antibacterial effect of printed latex coatings containing extracts rich in gallotannins and other types of phenolic compounds against 16 common spoilage and pathogenic bacteria of fish and meat. The largest zones of inhibition in disk diffusion assays were obtained with plastic films with coatings containing tannic acid alone, followed by tannic acid with phenolic-rich extracts of feijoa skin or mango seed. Significant inhibition was seen for all bacteria. This study shows that coatings with gallotannins as the main active ingredient can be printed onto commercial barrier films to control the bacteria that limit the shelf-life of fresh fish and meat.

Pyrolysis of polyethylene terephthalate containing real waste plastics using Ni loaded zeolite catalysts

NASA Astrophysics Data System (ADS)

Al-asadi, M.; Miskolczi, N.

2018-05-01

In this work the pyrolysis of polyethylene terephthalate (PET) containing real waste plastic was investigated using different Ni loaded catalysts: Ni/ZSM-5, Ni/y-zeolite, Ni/β-zeolite and Ni/natural zeolite (clinoptilolite). Raw materials were pyrolyzed in a horizontal tubular reactor between 600 and 900°C using 10% of catalysts. It was found, that both temperature increasing and catalysts presence can increase the gas yields, however owing to gasification reactions, the pyrolysis oil yield decreased with increasing temperature. Ni/y-zeolite catalyst had the most benefit in gas yield increasing at low temperature; however Ni/ZSM-5 showed advanced property in gas yield increasing at high temperature. Gases contained hydrogen, carbon oxides and hydrocarbons, which composition was significantly affected by catalysts. Ni loaded zeolites favoured to the formation of hydrogen and branched hydrocarbons; furthermore the concentrations of both CO and CO2 were also increased as function of elevated temperature. That phenomenon was attributed to the further decomposition of PET, especially to the side chain scission reactions. Owing to the Boudouard reaction, the ratio of CO2/CO can increased with temperature. Pyrolysis oils were the mixtures of n-saturated, n-unsaturated, branched, oxygen free aromatics and oxygenated hydrocarbons. Temperature increasing has a significant effect to the aromatization and isomerization reactions, while the catalysts can efficiently decreased the concentration of oxygen containing compounds.

Polynomials for crystal frameworks and the rigid unit mode spectrum

PubMed Central

Power, S. C.

2014-01-01

To each discrete translationally periodic bar-joint framework in , we associate a matrix-valued function defined on the d-torus. The rigid unit mode (RUM) spectrum of is defined in terms of the multi-phases of phase-periodic infinitesimal flexes and is shown to correspond to the singular points of the function and also to the set of wavevectors of harmonic excitations which have vanishing energy in the long wavelength limit. To a crystal framework in Maxwell counting equilibrium, which corresponds to being square, the determinant of gives rise to a unique multi-variable polynomial . For ideal zeolites, the algebraic variety of zeros of on the d-torus coincides with the RUM spectrum. The matrix function is related to other aspects of idealized framework rigidity and flexibility, and in particular leads to an explicit formula for the number of supercell-periodic floppy modes. In the case of certain zeolite frameworks in dimensions two and three, direct proofs are given to show the maximal floppy mode property (order N). In particular, this is the case for the cubic symmetry sodalite framework and some other idealized zeolites. PMID:24379422

Massive ordering and alignment of cylindrical micro-objects by photovoltaic optoelectronic tweezers.

PubMed

Elvira, Iris; Muñoz-Martínez, Juan F; Barroso, Álvaro; Denz, Cornelia; Ramiro, José B; García-Cabañes, Angel; Agulló-López, Fernando; Carrascosa, Mercedes

2018-01-01

Optical tools for manipulation and trapping of micro- and nano-objects are a fundamental issue for many applications in nano- and biotechnology. This work reports on the use of one such method, known as photovoltaic optoelectronics tweezers, to orientate and organize cylindrical microcrystals, specifically elongated zeolite L, on the surface of Fe-doped LiNbO 3 crystal plates. Patterns of aligned zeolites have been achieved through the forces and torques generated by the bulk photovoltaic effect. The alignment patterns with zeolites parallel or perpendicular to the substrate surface are highly dependent on the features of light distribution and crystal configuration. Moreover, dielectrophoretic chains of zeolites with lengths up to 100 μm have often been observed. The experimental results of zeolite trapping and alignment have been discussed and compared together with theoretical simulations of the evanescent photovoltaic electric field and the dielectrophoretic potential. They demonstrate the remarkable capabilities of the optoelectronic photovoltaic method to orientate and pattern anisotropic microcrystals. The combined action of patterning and alignment offers a unique tool to prepare functional nanostructures with potential applications in a variety of fields such as nonlinear optics or plasmonics.

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.

Amine-functionalized mesoporous ZSM-5 zeolite adsorbents for carbon dioxide capture

NASA Astrophysics Data System (ADS)

Wang, Yisong; Du, Tao; Song, Yanli; Che, Shuai; Fang, Xin; Zhou, Lifeng

2017-11-01

ZSM-5 type zeolite with mesoporous structure was prepared and then amine-functionalized with tetraethylenepentamine (TEPA) by wet impregnation method to form a series of CO2 adsorbents (ZTx). The structural properties of ZSM-5 and ZTx were characterized by XRD, FTIR, TGA/DTG, nitrogen adsorption/desorption, SEM and EDX techniques. The adsorption capacity of the adsorbents with different amine loading was measured at a temperature from 40 to 100 °C and the adsorption capacity of ZT7 was 1.80 mmol/g at 100 °C. The adsorption process and mechanism were studied by fitting the experimental data used the three adsorption kinetic models, and a complex physical and chemical mixing process was produced as the amine entered the surface and pore size of the zeolite. The high adsorption selectivity at 10% CO2 concentration and the stability of the five adsorption desorption cycles indicated that ZT7 is a suitable and promising CO2 adsorbent for the purification of industrial flue gas.

Solid-phase microextraction low temperature plasma mass spectrometry for the direct and rapid analysis of chemical warfare simulants in complex mixtures.

PubMed

Dumlao, Morphy C; Jeffress, Laura E; Gooding, J Justin; Donald, William A

2016-06-21

Solid-phase microextraction (SPME) is directly integrated with low temperature plasma ionisation mass spectrometry to rapidly detect organophosphate chemical warfare agent simulants and their hydrolysis products in chemical mixtures, including urine. In this sampling and ionization method, the fibre serves: (i) to extract molecules from their native environment, and (ii) as the ionization electrode that is used to desorb and ionize molecules directly from the SPME surface. By use of a custom fabricated SPME fibre consisting of a stainless steel needle coated with a Linde Type A (LTA) zeolitic microporous material and low temperature plasma mass spectrometry, protonated dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate (DEEP) and pinacolyl methylphosphonic acid (PinMPA) can be detected at less than 100 ppb directly in water and urine. Organophosphates were not readily detected by this approach using an uncoated needle in negative control experiments. The use of the LTA coating significantly outperformed the use of a high alumina Zeolite Socony Mobil-5 (ZSM-5) coating of comparable thickness that is significantly less polar than LTA. By conditioning the LTA probe by immersion in an aqueous CuSO4 solution, the ion abundance for protonated DMMP increased by more than 300% compared to that obtained without any conditioning. Sample recovery values were between 96 and 100% for each analyte. The detection of chemical warfare agent analogues and hydrolysis products required less than 2 min per sample. A key advantage of this sampling and ionization method is that analyte ions can be directly and rapidly sampled from chemical mixtures, such as urine and seawater, without sample preparation or chromatography for sensitive detection by mass spectrometry. This ion source should prove beneficial for portable mass spectrometry applications because relatively low detection limits can be obtained without the use of compressed gases, fluid pumps, and lasers. Moreover, the ion source is compact, can be powered with a 10 V battery, and is tolerant of complex mixtures.

Cost-Effective Filter Materials Coated with Silver Nanoparticles for the Removal of Pathogenic Bacteria in Groundwater

PubMed Central

Mpenyana-Monyatsi, Lizzy; Mthombeni, Nomcebo H.; Onyango, Maurice S.; Momba, Maggy N. B.

2012-01-01

The contamination of groundwater sources by pathogenic bacteria poses a public health concern to communities who depend totally on this water supply. In the present study, potentially low-cost filter materials coated with silver nanoparticles were developed for the disinfection of groundwater. Silver nanoparticles were deposited on zeolite, sand, fibreglass, anion and cation resin substrates in various concentrations (0.01 mM, 0.03 mM, 0.05 mM and 0.1 mM) of AgNO3. These substrates were characterised by SEM, EDS, TEM, particle size distribution and XRD analyses. In the first phase, the five substrates coated with various concentrations of AgNO3 were tested against E. coli spiked in synthetic water to determine the best loading concentration that could remove pathogenic bacteria completely from test water. The results revealed that all filters were able to decrease the concentration of E. coli from synthetic water, with a higher removal efficiency achieved at 0.1 mM (21–100%) and a lower efficiency at 0.01 mM (7–50%) concentrations. The cation resin-silver nanoparticle filter was found to remove this pathogenic bacterium at the highest rate, namely 100%. In the second phase, only the best performing concentration of 0.1 mM was considered and tested against presumptive E. coli, S. typhimurium, S. dysenteriae and V. cholerae from groundwater. The results revealed the highest bacteria removal efficiency by the Ag/cation resin filter with complete (100%) removal of all targeted bacteria and the lowest by the Ag/zeolite filter with an 8% to 67% removal rate. This study therefore suggests that the filter system with Ag/cation resin substrate can be used as a potential alternative cost-effective filter for the disinfection of groundwater and production of safe drinking water. PMID:22470290

Natural clinoptilolite composite membranes on tubular stainless steel supports for water softening.

PubMed

Adamaref, Solmaz; An, Weizhu; Jarligo, Maria Ophelia; Kuznicki, Tetyana; Kuznicki, Steven M

2014-01-01

Disk membranes generated from high-purity natural clinoptilolite mineral rock have shown promising water desalination and de-oiling performance. In order to scale up production of these types of membranes for industrial wastewater treatment applications, a coating strategy was devised. A composite mixture of natural clinoptilolite from St. Cloud (Winston, NM, USA) and aluminum phosphate was deposited on the inner surface of porous stainless steel tubes by the slip casting technique. The commercial porous stainless steel tubes were pre-coated with a TiO2 layer of about 10 μm. Phase composition and morphology of the coating materials were investigated using X-ray diffraction and scanning electron microscopy. Water softening performance of the fabricated membranes was evaluated using Edmonton (Alberta, Canada) municipal tap water as feed source. Preliminary experimental results show a high water flux of 7.7 kg/(m(2) h) and 75% reduction of hardness and conductivity in a once-through membrane process at 95 °C and feed pressure of 780 kPa. These results show that natural zeolite coated, stainless steel tubular membranes have high potential for large-scale purification of oil sands steam-assisted gravity drainage water at high temperature and pressure requirements.

Effective simultaneous removal of Pb(II) and Cd(II) ions by a new magnetic zeolite prepared from stem sweep

NASA Astrophysics Data System (ADS)

Safinejad, A.; Goudarzi, N.; Arab Chamjangali, M.; Bagherian, G.

2017-11-01

In this work, we prepared a new magnetic zeolite (MZ), as a sorbent, from stem sweep and used for the removal of lead and cadmium ions from aqueous solutions. Then the effective parameters involved in the removal efficiency of the studied ions were investigated. The synthetic MZ was characterized using x-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM). The best conditions for the preparation of MZ were found to be as follow: %Fe3O4 loaded  =  25, Si/Al  =  1.5, Na2O/SiO2  =  2.0, H2O/Na2O  =  75.0, crystallization time  =  20.0 h, and crystallization temperature  =  110 °C. The magnetic adsorbent was obtained by coating the zeolite with iron oxide nanoparticles. To study the sorption performance of the synthetic adsorbent, the single and binary systems including Pb(II) and Cd(II) ions were used. The effects of various parameters such as the solution pH, initial metal ion concentrations, amount of adsorbent, and contact time on the removal efficiency of the metal ions were studied. The results obtained showed that the adsorption isotherm data fitted well to the Langmuir isotherm, and that the adsorption kinetics of the metal ions in a binary system followed a pseudo-second order kinetic model.

The Use of Permeable Barriers to Inhibit Virus Migration in the Subsurface

NASA Astrophysics Data System (ADS)

Schulze-Makuch, D.; Guan, H.; Totten, J.; Couroux, E.; Endley, S.; Hielscher, F.; Emmert, S.; Pillai, S. D.

2001-12-01

Ground water is susceptible to fecal contamination due to leaking sewer lines, faulty septic tanks and careless disposal of septic wastes; a problem especially common in low-income areas with no public sewage system. Under these conditions, viral and bacterial infection rates have been shown to increase. However, potential for viral infections can be reduced if the viruses are prevented from reaching the drinking water wells. Laboratory and field studies were conducted to determine whether iron-coated sand (ICS), pure zeolite (PZ) and surfactant modified zeolites (SMZ) could be used to retard virus migration in soils. In the laboratory, using a model aquifer and MS2 bacteriophage (as an enteric virus indicator) we showed that ICS and especially SMZ was able to remove more than 90 % of the injected viruses under various conditions. The removal efficiency of viruses was also tested under field conditions using septic effluent and a constructed submerged wetland. The performance of the wetland was greatly enhanced when using SMZ as filter pack for a pumping well that withdrew water at a downstream location from the wetland. Our results suggest that submerged wetlands, particularly if combined with a pumping well that has a filter pack consisting of surfactant modified zeolite (rather than the usual sand and gravel pack), are efficient in removing viruses from septic effluent. The permeable barrier materials tested here are economical and could significantly reduce the potential for viral contamination of drinking water wells. >http://www.geo.utep.edu/pub/dirksm/geobiowater/geobiowater.htm

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.

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

Remediation of trichloroethylene by bio-precipitated and encapsulated palladium nanoparticles in a fixed bed reactor.

PubMed

Hennebel, Tom; Verhagen, Pieter; Simoen, Henri; De Gusseme, Bart; Vlaeminck, Siegfried E; Boon, Nico; Verstraete, Willy

2009-08-01

Trichloroethylene is a toxic and recalcitrant groundwater pollutant. Palladium nanoparticles bio-precipitated on Shewanella oneidensis were encapsulated in polyurethane, polyacrylamide, alginate, silica or coated on zeolites. The reactivity of these bio-Pd beads and zeolites was tested in batch experiments and trichloroethylene dechlorination followed first order reaction kinetics. The calculated k-values of the encapsulated catalysts were a factor of six lower compared to non-encapsulated bio-Pd. Bio-Pd, used as a catalyst, was able to dechlorinate 100 mgL(-1) trichloroethylene within a time period of 1h. The main reaction product was ethane; yet small levels of chlorinated intermediates were detected. Subsequently polyurethane cubes empowered with bio-Pd were implemented in a fixed bed reactor for the treatment of water containing trichloroethylene. The influent recycle configuration resulted in a cumulative removal of 98% after 22 h. The same reactor in a flow through configuration achieved removal rates up to 1059 mg trichloroethylene g Pd(-1)d(-1). This work showed that fixed bed reactors with bio-Pd polyurethane cubes can be instrumental for remediation of water contaminated with trichloroethylene.

Sub-micron Polymer–Zeolitic Imidazolate Framework Layered Hybrids via Controlled Chemical Transformation of Naked ZnO Nanocrystal Films

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

Meckler, Stephen M.; Li, Changyi; Queen, Wendy L.

2015-11-02

Here we show that sub-micron coatings of zeolitic imidazolate frameworks (ZIFs) and even ZIF–ZIF bilayers can be grown directly on polymers of intrinsic microporosity from zinc oxide (ZnO) nanocrystal precursor films, yielding a new class of all-microporous layered hybrids. The ZnO-to-ZIF chemical transformation proceeded in less than 30 min under microwave conditions using a solution of the imidazole ligand in N,N-dimethylformamide (DMF), water, or mixtures thereof. By varying the ratio of DMF to water, it was possible to control the morphology of the ZIF-on-polymer from isolated crystallites to continuous films. Grazing incidence X-ray diffraction was used to confirm the presencemore » of crystalline ZIF in the thin films, and X-ray absorption spectroscopy was used to quantify film purity, revealing films with little to no residual ZnO. The role solvent plays in the transformation mechanism is discussed in light of these findings, which suggest the ZnO nanocrystals may be necessary to localize heterogeneous nucleation of the ZIF to the polymer surface.« less

Sub-micron Polymer–Zeolitic Imidazolate Framework Layered Hybrids via Controlled Chemical Transformation of Naked ZnO Nanocrystal Films

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

Meckler, Stephen M.; Li, Changyi; Queen, Wendy L.

Here we show that sub-micron coatings of zeolitic imidazolate frameworks (ZIFs) and even ZIF–ZIF bilayers can be grown directly on polymers of intrinsic microporosity from zinc oxide (ZnO) nanocrystal precursor films, yielding a new class of all-microporous layered hybrids. The ZnO-to-ZIF chemical transformation proceeded in less than 30 min under microwave conditions using a solution of the imidazole ligand in N,N-dimethylformamide (DMF), water, or mixtures thereof. By varying the ratio of DMF to water, it was possible to control the morphology of the ZIF-on-polymer from isolated crystallites to continuous films. Grazing incidence X-ray diffraction was used to confirm the presencemore » of crystalline ZIF in the thin films, and X-ray absorption spectroscopy was used to quantify film purity, revealing films with little to no residual ZnO. The role solvent plays in the transformation mechanism is discussed in light of these findings, which suggest the ZnO nanocrystals may be necessary to localize heterogeneous nucleation of the ZIF to the polymer surface.« less

Development and Testing of Molecular Adsorber Coatings

NASA Technical Reports Server (NTRS)

Abraham, Nithin; Hasegawa, Mark; Straka, Sharon

2012-01-01

The effect of on-orbit molecular contamination has the potential to degrade the performance of spaceflight hardware and diminish the lifetime of the spacecraft. For example, sensitive surfaces, such as optical surfaces, electronics, detectors, and thermal control surfaces, are vulnerable to the damaging effects of contamination from outgassed materials. The current solution to protect these surfaces is through the use of zeolite coated ceramic adsorber pucks. However, these pucks and its additional complex mounting hardware requirements result in several disadvantages, such as size, weight, and cost related concerns, that impact the spacecraft design and the integration and test schedule. As a result, a new innovative molecular adsorber coating was developed as a sprayable alternative to mitigate the risk of on-orbit molecular contamination. In this study, the formulation for molecular adsorber coatings was optimized using various binders, pigment treatment methods, binder to pigment ratios, thicknesses, and spray application techniques. The formulations that passed coating adhesion and vacuum thermal cycling tests were further tested for its adsorptive capacity. Accelerated molecular capacitance tests were performed in an innovatively designed multi-unit system containing idealized contaminant sources. This novel system significantly increased the productivity of the testing phase for the various formulations that were developed. Work performed during the development and testing phases has demonstrated successful application of molecular adsorber coatings onto metallic substrates, as well as, very promising results for the adhesion performance and the molecular capacitance of the coating. Continued testing will assist in the qualification of molecular adsorber coatings for use on future contamination sensitive spaceflight missions.

Volatile organic compound adsorption in a gas-solid fluidized bed.

PubMed

Ng, Y L; Yan, R; Tsen, L T S; Yong, L C; Liu, M; Liang, D T

2004-01-01

Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas concentration. Concentrations up to 220 ppm for methanol and 75 ppm for isobutane were prepared using this method.

Activated zeolite--suitable carriers for microorganisms in anaerobic digestion processes?

PubMed

Weiß, S; Lebuhn, M; Andrade, D; Zankel, A; Cardinale, M; Birner-Gruenberger, R; Somitsch, W; Ueberbacher, B J; Guebitz, G M

2013-04-01

Plant cell wall structures represent a barrier in the biodegradation process to produce biogas for combustion and energy production. Consequently, approaches concerning a more efficient de-polymerisation of cellulose and hemicellulose to monomeric sugars are required. Here, we show that natural activated zeolites (i.e. trace metal activated zeolites) represent eminently suitable mineral microhabitats and potential carriers for immobilisation of microorganisms responsible for anaerobic hydrolysis of biopolymers stabilising related bacterial and methanogenic communities. A strategy for comprehensive analysis of immobilised anaerobic populations was developed that includes the visualisation of biofilm formation via scanning electron microscopy and confocal laser scanning microscopy, community and fingerprint analysis as well as enzyme activity and identification analyses. Using SDS polyacrylamide gel electrophoresis, hydrolytical active protein bands were traced by congo red staining. Liquid chromatography/mass spectroscopy revealed cellulolytical endo- and exoglucanase (exocellobiohydrolase) as well as hemicellulolytical xylanase/mannase after proteolytic digestion. Relations to hydrolytic/fermentative zeolite colonisers were obtained by using single-strand conformation polymorphism analysis (SSCP) based on amplification of bacterial and archaeal 16S rRNA fragments. Thereby, dominant colonisers were affiliated to the genera Clostridium, Pseudomonas and Methanoculleus. The specific immobilisation on natural zeolites with functional microbes already colonising naturally during the fermentation offers a strategy to systematically supply the biogas formation process responsive to population dynamics and process requirements.

Synthesis and characterization of microporous inorganic membranes for propylene/propane separation

NASA Astrophysics Data System (ADS)

Ma, Xiaoli

Membrane-based gas separation is promising for efficient propylene/propane (C3H6/C3H8) separation with low energy consumption and minimum environment impact. Two microporous inorganic membrane candidates, MFI-type zeolite membrane and carbon molecular sieve membrane (CMS) have demonstrated excellent thermal and chemical stability. Application of these membranes into C3H6/C3H 8 separation has not been well investigated. This dissertation presents fundamental studies on membrane synthesis, characterization and C3H 6/C3H8 separation properties of MFI zeolite membrane and CMS membrane. MFI zeolite membranes were synthesized on α-alumina supports by secondary growth method. Novel positron annihilation spectroscopy (PAS) techniques were used to non-destructively characterize the pore structure of these membranes. PAS reveals a bimodal pore structure consisting of intracrystalline zeolitic micropores of ~0.6 nm in diameter and irregular intercrystalline micropores of 1.4 to 1.8 nm in size for the membranes. The template-free synthesized membrane exhibited a high permeance but a low selectivity in C3H 6/C3H8 mixture separation. CMS membranes were synthesized by coating/pyrolysis method on mesoporous gamma-alumina support. Such supports allow coating of thin, high-quality polymer films and subsequent CMS membranes with no infiltration into support pores. The CMS membranes show strong molecular sieving effect, offering a high C3H 6/C3H8 mixture selectivity of ~30. Reduction in membrane thickness from 500 nm to 300 nm causes an increase in C3H8 permeance and He/N2 selectivity, but a decrease in the permeance of He, N 2 and C3H6 and C3H6/C 3H8 selectivity. This can be explained by the thickness dependent chain mobility of the polymer film resulting in final carbon membrane of reduced pore size with different effects on transport of gas of different sizes, including possible closure of C3H6-accessible micropores. CMS membranes demonstrate excellent C3H6/C 3H8 separation performance over a wide range of feed pressure, composition and operation temperature. No plasticization was observed at a feed pressure up to 100 psi. The permeation and separation is mainly controlled by diffusion instead of adsorption. CMS membrane experienced a decline in permeance, and an increase in selectivity over time under on-stream C 3H6/C3H8 separation. This aging behavior is due to the reduction in effective pore size and porosity caused by oxygen chemisorption and physical aging of the membrane structure.

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.

Catalysts as sensors--a promising novel approach in automotive exhaust gas aftertreatment.

PubMed

Moos, Ralf

2010-01-01

Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NO(x) traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NO(x)-loading of lean NO(x) traps, and the soot loading of Diesel particulate filters.

Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment

PubMed Central

Moos, Ralf

2010-01-01

Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NOx traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NOx-loading of lean NOx traps, and the soot loading of Diesel particulate filters. PMID:22163575

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.

Effect of vanadium contamination on the framework and micropore structure of ultra stable Y-zeolite.

PubMed

Etim, U J; Xu, B; Ullah, Rooh; Yan, Z

2016-02-01

Y-zeolites are the main component of fluid catalytic cracking (FCC) catalyst for conversion of crude petroleum to products of high demand including transportation fuel. We investigated effects of vanadium which is present as one of the impurities in FCC feedstock on the framework and micropore structure of ultra-stable (US) Y-zeolite. The zeolite samples were prepared and characterized using standard techniques including: (1) X-ray diffraction, (2) N2 adsorption employing non local density functional theory method, NLDFT, (3) Transmittance and Pyridine FTIR, (4) Transmittance electron microscopy (TEM), and (5) (27)Al and (29)Si MAS-NMR. Results revealed that in the presence of steam, vanadium caused excessive evolution of non inter-crystalline mesopores and structural damage. The evolved mesopore size averaged about 25.0nm at 0.5wt.% vanadium loading, far larger than mesopore size in zeolitic materials with improved hydrothermal stability and performance for FCC catalyst. A mechanism of mesopore formation based on accelerated dealumination has been proposed and discussed. Vanadium immobilization experiments conducted to mitigate vanadium migration into the framework clearly showed vanadium is mobile at reaction conditions. From the results, interaction of vanadium with the passivator limits and decreases mobility and activity of vanadium into inner cavities of the zeolite capable of causing huge structure breakdown and acid sites destruction. This study therefore deepens insight into the causes of alteration in activity and selectivity of vanadium contaminated catalyst and hints on a possible mechanism of passivation in vanadium passivated FCC catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

Identification of tert-Butyl Cations in Zeolite H-ZSM-5: Evidence from NMR Spectroscopy and DFT Calculations.

PubMed

Dai, Weili; Wang, Chuanming; Yi, Xianfeng; Zheng, Anmin; Li, Landong; Wu, Guangjun; Guan, Naijia; Xie, Zaiku; Dyballa, Michael; Hunger, Michael

2015-07-20

Experimental evidence for the presence of tert-butyl cations, which are important intermediates in acid-catalyzed heterogeneous reactions, on solid acids has still not been provided to date. By combining density functional theory (DFT) calculations with (1)H/(13)C magic-angle-spinning NMR spectroscopy, the tert-butyl cation was successfully identified on zeolite H-ZSM-5 upon conversion of isobutene by capturing this intermediate with ammonia. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Epoxy Nanocomposites Containing Zeolitic Imidazolate Framework-8.

PubMed

Liu, Cong; Mullins, Michael; Hawkins, Spencer; Kotaki, Masaya; Sue, Hung-Jue

2018-01-10

Zeolitic imidazole framework-8 (ZIF-8) is utilized as a functional filler and a curing agent in the preparation of epoxy nanocomposites. The imidazole group on the surface of the ZIF-8 initiates epoxy curing, resulting in covalent bonding between the ZIF-8 crystals and epoxy matrix. A substantial reduction in dielectric constant and increase in tensile modulus were observed. The implication of the present study for utilization of metal-organic framework to improve physical and mechanical properties of polymeric matrixes is discussed.

Solar-Light-Driven Renewable Butanol Separation by Core-Shell Ag@ZIF-8 Nanowires.

PubMed

Liu, Xu; He, Liangcan; Zheng, Jianzhong; Guo, Jun; Bi, Feng; Ma, Xiang; Zhao, Kun; Liu, Yaling; Song, Rui; Tang, Zhiyong

2015-06-03

Core-shell Ag@ZIF-8 nanowires, where single Ag nanowires are coated with uniform zeolitic-imidazolate-framework-8 (ZIF-8) shells, successfully realize renewable adsorptive separation of low concentrations of butanol from an aqueous medium under solar light irradiation by taking advantage of the exceptional adsorption capability of the ZIF-8 shells toward butanol and the unique plasmonic photothermal effect of the Ag nanowire cores. Impressively, the high separation efficiency is maintained as almost unchanged, even after 10 adsorption/desorption cycles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Layered zeolite materials and methods related thereto

DOEpatents

Tsapatsis, Michael; Maheshwari, Sudeep; Bates, Frank S; Koros, William J

2013-08-06

A novel oxide material (MIN-I) comprising YO.sub.2; and X.sub.2O.sub.3, wherein Y is a tetravalent element and X is a trivalent element, wherein X/Y=O or Y/X=30 to 100 is provided. Surprisingly, MIN-I can be reversibly deswollen. MIN-I can further be combined with a polymer to produce a nanocomposite, depolymerized to produce predominantly fully exfoliated layers (MIN-2), and pillared to produce a pillared oxide material (MIN-3), analogous to MCM-36. The materials are useful in a wide range of applications, such as catalysts, thin films, membranes, and coatings.

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.

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.

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 measurement of 2D-ACAR can well be an effective in-situ microprobe that could have important practical applications in internal surface characterization of zeolite catalysts in general.

Development of electroactive polymer nanocomposites with porous structured materials

NASA Astrophysics Data System (ADS)

Lopes, Ana Catarina Teixeira Castro

Electroactive polymer composites are interesting materials for advance technological applications due to the possibility to combine the electroactive properties of the polymer matrix with a large variety of fillers that allow tailored responses for specific applications. The best all-around electroactive polymers are poly(vinylidene fluoride) (PVDF) and its copolymers which allied with the properties of porous zeolite materials, with tailored shape, size and Si/Al ratio, among others, leads to the possibility of development of promising PVDF/zeolite composites. In this way, a study of the structural, thermal and electrical properties of PVDF composites prepared with different framework zeolite types (LTL, LTA, FAU and MFI), different polymer solvents (DMF, DMSO, TEP) and different zeolite (NaY) concentrations (4, 16, 24 and 32 wt %) was performed. Further, the dielectric response, electrical conductivity and electric modulus of the composites were investigated as a function of NaYzeolite content. The zeolite influence on the electroactive gamma-phase crystallization of PVDF was explored, as well as the effect of clay layered structure (Montmorillonite, Kaolinite and Laponite) on the electroactive gamma-phase nucleation and on the optical transparency of the composite. It was found that the obtained composites showed an electrical response dependence on the pore structure and chemical content of the inorganic host. The dielectric response of the composites is directly related to the Si/Al ratio, leading zeolites with lower Si/Al ratios to larger dielectric responses and encapsulation efficiencies in the composites. It was also found that the zeolite content strongly influences the macroscopic response of dielectric response, which increases for increasing filler content. The dielectric constant at room temperature reaches values larger than 1000 for the 32 wt.% composite at 1 kHz what is mainly attributed to restricted ion mobility and interfacial polarization effects due to the zeolite inclusion, leading also to high dielectric losses. For the higher zeolite concentrations the composite d.c. electrical conductivity is characterized by two conducting regimes separated by a concentration independent breaking voltage of 4 V, which is associated to an intrazeolite charge transport. Dielectric relaxation studies show that the main relaxation process (?-relaxation) of the amorphous phase of the polymer matrix is not affected by the presence of the zeolite and, in a similar way, the zeolite low temperature relaxation is not significantly affected by the polymer phase. On the other hand, the electric modulus formalism reveals significant contributions of the fillers to the electrical permittivity and conductivity of the composites. The presence of the zeolite particles increases a.c. conductivity and the Maxwell-Wagner-Sillars contribution that is predominant at low frequencies with respect to the ohmic contribution to permittivity. The ability of zeolites to induce the eletroactive gamma-phase nucleation of PVDF is directly dependent on the Si/Al ratio and zeolite content; however it only occurs when the composite is melted at temperatures below 200 ºC. The complete ?-phase crystallization of the polymer crystalline phase occurs for a filler content of 16 wt% of LTA or FAU zeolite structure. The even higher surface interaction of clays when exfoliated leads to the same phenomenon with an amount of 0.50 % of Montmorillonite clay content. The electroactivity of the material has been proven by measuring the piezoelectric d33 response of the material, which presents a value of -7 pC/N, lower than for beta-PVDF obtained by mechanical stretching but still among the largest coefficients obtained for polymers. Further, the optical transmittance in the visible range is strongly enhanced with respect to the transmittance of the pure polymer. The development, characterization and physical-chemical understanding of these PVDF/zeolite and PVDF/clay composites resulted in suitable materials for applications in diverse areas including battery separator membranes and biomedical applications.

Reducing Arsenic Concentration in Panax notoginseng via Contaminant Immobilization in Soil Using Fe–Ce Oxide

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

Lin, Longyong; Zhong, Lirong; Yan, Xiulan

Panax notoginseng (Burk.) F.H. Chen, a precious Chinese medicine, is currently confronted with arsenic (As) contamination in China due to soil pollution. Our previous research demonstrated that Fe(0) and zeolite had certain inhibitory effect on As accumulation in P. notoginseng. To further increase the As immobilization efficiency and to reduce As accumulation in the plant, a synthetic iron material (Fe-Ce oxide, FC) with high As adsorption capacity was tested for As remediation. P. notoginseng was planted in As-contaminated soil when the FC amendment was applied to the soil. The As leaching behavior of the treated soil and As accumulation inmore » P. notoginseng were evaluated. Results showed that FC more effectively immobilized As than Fe(0) and zeolite in soils with high As concentrations. When the FC dosage was 0.5 wt.%, As concentration of P. notoginseng root (the main medicinal part) decreased by 55.8%, and its biomass increased by 54.6%. FC could reduce the non-specifically adsorbed As fraction (F1) and specifically adsorbed As fraction (F2) by 21.8%-30.6% and 4.6%-16.6%, respectively, thus reducing the TCLP (Toxicity Characteristic Leaching Procedure) concentration by 40.6%-67.0%. The finding of iron plaque coating on root and its function as a barrier for As uptake for P. notoginseng was reported for the first time. The occurrence of iron plaque led to As concentration reduction in the phellem and xylem/phloem by 65.6%-79.7% and 43.2%-70.2%, respectively, thus raising the proportion of As(III) to 75%. This study is of significance in developing As contamination control in P. notoginseng planting areas.« less

An innovative approach to bioremediation of mercury contaminated soils from industrial mining operations.

PubMed

McCarthy, Damien; Edwards, Grant C; Gustin, Mae S; Care, Andrew; Miller, Matthieu B; Sunna, Anwar

2017-10-01

Soils contaminated with mercury (Hg) have proved expensive and logistically difficult to remediate. Research continues into finding suitable environmentally-friendly and efficient ways of achieving this end. Bioremediation is an option, which employs the strategies microorganisms have evolved to deal with Hg. One microbial strategy involves uptake and intracellular volatilisation of mercuric ions, which passively diffuse from the cell and back into the atmosphere. In this work, Pseudomonas veronii cells grown to stationary phase were immobilised in a xanthan gum-based biopolymer via encapsulation. The P. veronii-biopolymer mix was then coated onto natural zeolite granules. Zeolite immobilised cells remained viable for at least 16 weeks stored under ambient room temperature. Furthermore, the immobilised cells were shown to retain both viability and Hg volatilisation functionality after transportation from Australia to the USA, where they were applied to Hg contaminated soil. Maximum flux rates exceeded 10 μg Hg m 2  h -1 from mine tailings (≈7 mg kg -1  Hg with 50% v/v water). This was 4 orders of magnitude above background flux levels. It is envisioned that emitted gaseous elemental mercury (GEM) can be readily captured, and transformed back into metallic Hg, which can then be stored appropriately or recycled. This breaks the Hg cycle, as GEM is no longer translocated back to the atmospheric compartment. The immobilising excipients used in this research overcome many logistical issues with delivery of suitable microbial loads to locations of mercury contamination and presents a facile and inexpensive method of augmenting contaminated sites with selected microbial consortia for bioremediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

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).

Subglacial hydrothermal alteration minerals in Jökulhlaup deposits of Southern Iceland, with implications for detecting past or present habitable environments on Mars.

PubMed

Warner, Nicholas H; Farmer, Jack D

2010-06-01

Jökulhlaups are terrestrial catastrophic outfloods, often triggered by subglacial volcanic eruptions. Similar volcano-ice interactions were likely important on Mars where magma/lava may have interacted with the planet's cryosphere to produce catastrophic floods. As a potential analogue to sediments deposited during martian floods, the Holocene sandurs of Iceland are dominated by basaltic clasts derived from the subglacial environment and deposited during jökulhlaups. Palagonite tuffs and breccias, present within the deposits, represent the primary alteration lithology. The surface abundance of palagonite on the sandurs is 1-20%. X-ray diffraction (XRD) analysis of palagonite breccias confirms a mineral assemblage of zeolites, smectites, low-quartz, and kaolinite. Oriented powder X-ray diffractograms (< 2 microm fraction) for palagonite breccia clasts and coatings reveal randomly ordered smectite, mixed layer smectite/illite, zeolites, and quartz. Visible light-near infrared (VNIR) and shortwave infrared (SWIR) lab spectroscopic data of the same palagonite samples show H2O/OH(-) absorptions associated with clays and zeolites. SWIR spectra derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images of the sandurs reveal Al-OH(-) and Si-OH(-) absorption features. The identified alteration mineral assemblage is consistent with low temperature (100-140 degrees C) hydrothermal alteration of basaltic material within the subglacial environment. These results suggest that potential martian analog sites that contain a similar suite of hydrated minerals may be indicative of past hydrothermal activity and locations where past habitable environments for microbial life may be found.

Interaction between the exchanged Mn2+ and Yb3+ ions confined in zeolite-Y and their luminescence behaviours

PubMed Central

Ye, Shi; Sun, Jiayi; Yi, Xiong; Wang, Yonggang; Zhang, Qinyuan

2017-01-01

Luminescent zeolites exchanged with two distinct and interacted emissive ions are vital but less-studied for the potential applications in white light emitting diodes, solar cells, optical codes, biomedicine and so on. Typical transition metal ion Mn2+ and lanthanide ion Yb3+ are adopted as a case study via their characteristic transitions and the interaction between them. The option is considered with that the former with d-d transition has a large gap between the first excited state 4T1 and the ground state 6A1 (normally >17,000 cm−1) while the latter with f-f transition has no metastable excited state above 10,000 cm−1, which requires the vicinity of these two ions for energy transfer. The results of various characterizations, including BET measurement, photoluminescence spectroscopy, solid-state NMR, and X-ray absorption spectroscopy, etc., show that Yb3+ would preferably enter into the zeolite-Y pores and introduction of Mn2+ would cause aggregation of each other. Herein, cation-cation repulsion may play a significant role for the high valence of Mn2+ and Yb3+ when exchanging the original cations with +1 valence. Energy transfer phenomena between Mn2+ and Yb3+ occur only at elevated contents in the confined pores of zeolite. The research would benefit the design of zeolite composite opto-functional materials. PMID:28393920

Preparation of highly ordered cubic NaA zeolite from halloysite mineral for adsorption of ammonium ions.

PubMed

Zhao, Yafei; Zhang, Bing; Zhang, Xiang; Wang, Jinhua; Liu, Jindun; Chen, Rongfeng

2010-06-15

Well-ordered cubic NaA zeolite was first synthesized using natural halloysite mineral with nanotubular structure as source material by hydro-thermal method. SEM and HRTEM images indicate that the synthesized NaA zeolite is cubic-shaped crystal with planar surface, well-defined edges and symmetrical and uniform pore channels. The adsorption behavior of ammonium ions (NH(4)(+)) from aqueous solution onto NaA zeolite was investigated as a function of parameters such as equilibrium time, pH, initial NH(4)(+) concentration, temperature and competitive cations. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. A maximum adsorption capacity of 44.3 mg g(-1) of NH(4)(+) was achieved. The regeneration and reusable ability of this adsorbent was evaluated, and the results indicated that the recovered adsorbent could be used again for NH(4)(+) removal with nearly constant adsorption capacity. Thermodynamic parameters such as change in free energy (DeltaG(0)), enthalpy (DeltaH(0)) and entropy (DeltaS(0)) were also determined, which indicated that the adsorption was a spontaneous and exothermic process at ambient conditions. Compared with other adsorbents, the as-synthesized NaA zeolite displays a faster adsorption rate and higher adsorption capacity, which implies potential application for removing NH(4)(+) pollutants from wastewaters. Copyright 2010 Elsevier B.V. All rights reserved.

Interaction between the exchanged Mn2+ and Yb3+ ions confined in zeolite-Y and their luminescence behaviours

NASA Astrophysics Data System (ADS)

Ye, Shi; Sun, Jiayi; Yi, Xiong; Wang, Yonggang; Zhang, Qinyuan

2017-04-01

Luminescent zeolites exchanged with two distinct and interacted emissive ions are vital but less-studied for the potential applications in white light emitting diodes, solar cells, optical codes, biomedicine and so on. Typical transition metal ion Mn2+ and lanthanide ion Yb3+ are adopted as a case study via their characteristic transitions and the interaction between them. The option is considered with that the former with d-d transition has a large gap between the first excited state 4T1 and the ground state 6A1 (normally >17,000 cm-1) while the latter with f-f transition has no metastable excited state above 10,000 cm-1, which requires the vicinity of these two ions for energy transfer. The results of various characterizations, including BET measurement, photoluminescence spectroscopy, solid-state NMR, and X-ray absorption spectroscopy, etc., show that Yb3+ would preferably enter into the zeolite-Y pores and introduction of Mn2+ would cause aggregation of each other. Herein, cation-cation repulsion may play a significant role for the high valence of Mn2+ and Yb3+ when exchanging the original cations with +1 valence. Energy transfer phenomena between Mn2+ and Yb3+ occur only at elevated contents in the confined pores of zeolite. The research would benefit the design of zeolite composite opto-functional materials.

Prediction of zeolite-cement-sand unconfined compressive strength using polynomial neural network

NASA Astrophysics Data System (ADS)

MolaAbasi, H.; Shooshpasha, I.

2016-04-01

The improvement of local soils with cement and zeolite can provide great benefits, including strengthening slopes in slope stability problems, stabilizing problematic soils and preventing soil liquefaction. Recently, dosage methodologies are being developed for improved soils based on a rational criterion as it exists in concrete technology. There are numerous earlier studies showing the possibility of relating Unconfined Compressive Strength (UCS) and Cemented sand (CS) parameters (voids/cement ratio) as a power function fits. Taking into account the fact that the existing equations are incapable of estimating UCS for zeolite cemented sand mixture (ZCS) well, artificial intelligence methods are used for forecasting them. Polynomial-type neural network is applied to estimate the UCS from more simply determined index properties such as zeolite and cement content, porosity as well as curing time. In order to assess the merits of the proposed approach, a total number of 216 unconfined compressive tests have been done. A comparison is carried out between the experimentally measured UCS with the predictions in order to evaluate the performance of the current method. The results demonstrate that generalized polynomial-type neural network has a great ability for prediction of the UCS. At the end sensitivity analysis of the polynomial model is applied to study the influence of input parameters on model output. The sensitivity analysis reveals that cement and zeolite content have significant influence on predicting UCS.

Advances in theory and their application within the field of zeolite chemistry.

PubMed

Van Speybroeck, Veronique; Hemelsoet, Karen; Joos, Lennart; Waroquier, Michel; Bell, Robert G; Catlow, C Richard A

2015-10-21

Zeolites are versatile and fascinating materials which are vital for a wide range of industries, due to their unique structural and chemical properties, which are the basis of applications in gas separation, ion exchange and catalysis. Given their economic impact, there is a powerful incentive for smart design of new materials with enhanced functionalities to obtain the best material for a given application. Over the last decades, theoretical modeling has matured to a level that model guided design has become within reach. Major hurdles have been overcome to reach this point and almost all contemporary methods in computational materials chemistry are actively used in the field of modeling zeolite chemistry and applications. Integration of complementary modeling approaches is necessary to obtain reliable predictions and rationalizations from theory. A close synergy between experimentalists and theoreticians has led to a deep understanding of the complexity of the system at hand, but also allowed the identification of shortcomings in current theoretical approaches. Inspired by the importance of zeolite characterization which can now be performed at the single atom and single molecule level from experiment, computational spectroscopy has grown in importance in the last decade. In this review most of the currently available modeling tools are introduced and illustrated on the most challenging problems in zeolite science. Directions for future model developments will be given.

Monocopper active site for partial methane oxidation in Cu-exchanged 8MR zeolites

DOE PAGES

Kulkarni, Ambarish R.; Zhao, Zhi -Jian; Siahrostami, Samira; ...

2016-08-17

Direct conversion of methane to methanol using oxygen is experiencing renewed interest owing to the availability of new natural gas resources. Copper-exchanged zeolites such as mordenite and ZSM-5 have shown encouraging results, and di- and tri-copper species have been suggested as active sites. Recently, small eight-membered ring (8MR) zeolites including SSZ-13, -16, and -39 have been shown to be active for methane oxidation, but the active sites and reaction mechanisms in these 8MR zeolites are not known. In this work, we use density functional theory (DFT) calculations to systematically evaluate monocopper species as active sites for the partial methane oxidationmore » reaction in Cu-exchanged SSZ-13. On the basis of kinetic and thermodynamic arguments, we suggest that [Cu IIOH] + species in the 8MR are responsible for the experimentally observed activity. Furthermore, our results successfully explain the available spectroscopic data and experimental observations including (i) the necessity of water for methanol extraction and (ii) the effect of Si/Al ratio on the catalyst activity. Monocopper species have not yet been suggested as an active site for the partial methane oxidation reaction, and our results suggest that [Cu IIOH] + active site may provide complementary routes for methane activation in zeolites in addition to the known [Cu–O–Cu] 2+ and Cu 3O 3 motifs.« less

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.

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.

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

Revealing Lattice Expansion of Small-Pore Zeolite Catalysts during the Methanol-to-Olefins Process Using Combined Operando X-ray Diffraction and UV-vis Spectroscopy.

PubMed

Goetze, Joris; Yarulina, Irina; Gascon, Jorge; Kapteijn, Freek; Weckhuysen, Bert M

2018-03-02

In small-pore zeolite catalysts, where the size of the pores is limited by eight-ring windows, aromatic hydrocarbon pool molecules that are formed inside the zeolite during the Methanol-to-Olefins (MTO) process cannot exit the pores and are retained inside the catalyst. Hydrocarbon species whose size is comparable to the size of the zeolite cage can cause the zeolite lattice to expand during the MTO process. In this work, the formation of retained hydrocarbon pool species during MTO at a reaction temperature of 400 °C was followed using operando UV-vis spectroscopy. During the same experiment, using operando X-ray Diffraction (XRD), the expansion of the zeolite framework was assessed, and the activity of the catalyst was measured using online gas chromatography (GC). Three different small-pore zeolite frameworks, i.e., CHA, DDR, and LEV, were compared. It was shown using operando XRD that the formation of retained aromatic species causes the zeolite lattice of all three frameworks to expand. Because of the differences in the zeolite framework dimensions, the nature of the retained hydrocarbons as measured by operando UV-vis spectroscopy is different for each of the three zeolite frameworks. Consequently, the magnitude and direction of the zeolite lattice expansion as measured by operando XRD also depends on the specific combination of the hydrocarbon species and the zeolite framework. The catalyst with the CHA framework, i.e., H-SSZ-13, showed the biggest expansion: 0.9% in the direction along the c -axis of the zeolite lattice. For all three zeolite frameworks, based on the combination of operando XRD and operando UV-vis spectroscopy, the hydrocarbon species that are likely to cause the expansion of the zeolite cages are presented; methylated naphthalene and pyrene in CHA, 1-methylnaphthalene and phenalene in DDR, and methylated benzene and naphthalene in LEV. Filling of the zeolite cages and, as a consequence, the zeolite lattice expansion causes the deactivation of these small-pore zeolite catalysts during the MTO process.

Revealing Lattice Expansion of Small-Pore Zeolite Catalysts during the Methanol-to-Olefins Process Using Combined Operando X-ray Diffraction and UV–vis Spectroscopy

PubMed Central

2018-01-01

In small-pore zeolite catalysts, where the size of the pores is limited by eight-ring windows, aromatic hydrocarbon pool molecules that are formed inside the zeolite during the Methanol-to-Olefins (MTO) process cannot exit the pores and are retained inside the catalyst. Hydrocarbon species whose size is comparable to the size of the zeolite cage can cause the zeolite lattice to expand during the MTO process. In this work, the formation of retained hydrocarbon pool species during MTO at a reaction temperature of 400 °C was followed using operando UV–vis spectroscopy. During the same experiment, using operando X-ray Diffraction (XRD), the expansion of the zeolite framework was assessed, and the activity of the catalyst was measured using online gas chromatography (GC). Three different small-pore zeolite frameworks, i.e., CHA, DDR, and LEV, were compared. It was shown using operando XRD that the formation of retained aromatic species causes the zeolite lattice of all three frameworks to expand. Because of the differences in the zeolite framework dimensions, the nature of the retained hydrocarbons as measured by operando UV–vis spectroscopy is different for each of the three zeolite frameworks. Consequently, the magnitude and direction of the zeolite lattice expansion as measured by operando XRD also depends on the specific combination of the hydrocarbon species and the zeolite framework. The catalyst with the CHA framework, i.e., H-SSZ-13, showed the biggest expansion: 0.9% in the direction along the c-axis of the zeolite lattice. For all three zeolite frameworks, based on the combination of operando XRD and operando UV–vis spectroscopy, the hydrocarbon species that are likely to cause the expansion of the zeolite cages are presented; methylated naphthalene and pyrene in CHA, 1-methylnaphthalene and phenalene in DDR, and methylated benzene and naphthalene in LEV. Filling of the zeolite cages and, as a consequence, the zeolite lattice expansion causes the deactivation of these small-pore zeolite catalysts during the MTO process. PMID:29527401

Integrated synthesis of zeolites 4A and Na-P1 using coal fly ash for application in the formulation of detergents and swine wastewater treatment.

PubMed

Cardoso, Ariela M; Horn, Martha B; Ferret, Lizete S; Azevedo, Carla M N; Pires, Marçal

2015-04-28

Several researchers have reported zeolite synthesis using coal ash for a wide range of applications. However, little attention has been given to green processes, including moderate synthesis conditions, using waste as raw material and effluent reuse or reduction. In this study, Brazilian coal fly ashes were used for integrated synthesis of zeolites 4A and Na-P1 by two different routes and under moderate operating conditions (temperature and pressure). Both procedures produced zeolites with similar conversions (zeolite 4A at 82% purity and zeolite Na-P1 at 57-61%) and high CEC values (zeolites 4A: 4.5meqCa(2+)g(-1) and zeolites Na-P1: 2.6-2.8meqNH4(+)g(-1)). However, process 1 generated less effluent for the zeolite mass produced (7mLg(-1)), with low residual Si and Al levels and 74% of the Si available in the coal fly ash incorporated into the zeolite, while only 55% is used in process 2. For use as a builder in detergents, synthetic zeolite 4A exhibited conformity parameters equal to or greater than those of the commercial zeolite adopted as reference. Treatment of swine wastewater with zeolite Na-P1 resulted in a high removal capacity for total ammoniacal nitrogen (31mgg(-1)). Copyright © 2015 Elsevier B.V. All rights reserved.

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...

Impact of Zeolite Aging in Hot Liquid Water on Activity for Acid-Catalyzed Dehydration of Alcohols.

PubMed

Vjunov, Aleksei; Derewinski, Miroslaw A; Fulton, John L; Camaioni, Donald M; Lercher, Johannes A

2015-08-19

The location and stability of Brønsted acid sites catalytically active in zeolites during aqueous phase dehydration of alcohols were studied on the example of cyclohexanol. The catalytically active hydronium ions originate from Brønsted acid sites (BAS) of the zeolite that are formed by framework tetrahedral Si atom substitution by Al. Al K-edge extended X-ray absorption fine structure (EXAFS) and (27)Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopies in combination with density functional theory (DFT) calculations are used to determine the distribution of tetrahedral Al sites (Al T-sites) both qualitatively and quantitatively for both parent and HBEA catalysts aged in water prior to catalytic testing. The aging procedure leads to partial degradation of the zeolite framework evidenced from the decrease of material crystallinity (XRD) as well as sorption capacity (BET). With the exception of one commercial zeolite sample, which had the highest concentration of framework silanol-defects, there is no evidence of Al coordination modification after aging in water. The catalyst weight-normalized dehydration rate correlated best with the sum of strong and weak Brønsted acidic protons both able to generate the hydrated hydronium ions. All hydronium ions were equally active for the acid-catalyzed reactions in water. Zeolite aging in hot water prior to catalysis decreased the weight normalized dehydration reaction rate compared to that of the parent HBEA, which is attributed to the reduced concentration of accessible Brønsted acid sites. Sites are hypothesized to be blocked due to reprecipitation of silica dissolved during framework hydrolysis in the aging procedure.

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.

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.

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.

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)

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 zeolites have been proposed and verified. In addition to a significant reduction in liquid wastes and a remarkable increase in zeolite yields, the solvent-free synthesis of zeolites exhibits more unprecedented benefits, including (i) the formation of hierarchical micro-, meso-, and macrostructures, which benefit the mass transfer in the reactions, (ii) rapid synthesis at higher temperatures, which greatly improve the space-time yields of zeolites, and (iii) construction of a novel catalytic system for encapsulation of metal nanoparticles and metal oxide particles within zeolite crystals synergistically combining the advantages of catalytic metal nanoparticles and metal oxide particles (high activity) and zeolites (shape selectivity). We believe that the concept of "solvent-free synthesis of zeolites" would open a door for deep understanding of zeolite crystallization and the design of efficient zeolitic catalysts.

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.

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.

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.

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.

Identification of the silver state in the framework of Ag-containing zeolite by XRD, FTIR, photoluminescence, 109Ag NMR, EPR, DR UV-vis, TEM and XPS investigations.

PubMed

Popovych, Nataliia; Kyriienko, Pavlo; Soloviev, Sergiy; Baran, Rafal; Millot, Yannick; Dzwigaj, Stanislaw

2016-10-26

Silver has been identified in the framework of Ag x SiBEA zeolites (where x = 3-6 Ag wt%) by the combined use of XRD, 109 Ag MAS NMR, FTIR, diffuse reflectance UV-visible, EPR and XPS spectroscopy. The incorporation of Ag ions into the framework of SiBEA zeolite has been evidenced by XRD. The consumption of OH groups as a result of their reaction with the silver precursor has been monitored by FTIR and photoluminescence spectroscopy. The changes in the silver state as a function of Ag content and thermal and hydrogen treatment at 573 K have been identified by 109 Ag MAS NMR, EPR, DR UV-visible, TEM and XPS investigations. The acidity of AgSiBEA has been investigated by FTIR spectroscopy of adsorbed CO and pyridine used as probe molecules.

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.

Polydopamine-reinforced magnetization of zeolitic imidazolate framework ZIF-7 for magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from the air-water environment.

PubMed

Zhang, Suling; Yao, Weixuan; Ying, Jianbo; Zhao, Hongting

2016-06-24

Zeolitic imidazolate frameworks (ZIFs) consist of metal nodes connected to imidazolate linkers, having both the properties of metal-organic frameworks (MOFs) and inorganic zeolites, such as controllable pore sizes, high porosity and surface areas, as well as exceptional thermal and chemical stability, thereby making them a class of attractive materials for diverse analytical applications. In this study, we reported a facile magnetization process of ZIF-7 (zinc benzimidazolate) for simultaneous magnetic extraction of polycyclic aromatic hydrocarbons (PAHs) by simply mixing ZIF-7 and polydopamine (PDA)-coated Fe3O4 nanoparticles (PDA@Fe3O4) in solutions. Functional groups (-OH and -NH2), provided by PDA as a highly efficient molecular linker, could attract and anchor ZIF-7 through noncovalent adsorption and covalent cross-link interactions, thereby promoting the complete magnetization of ZIFs and enhancing their stability and reusability. The bridging ligand benzimidazolate, could be bonded with PAHs because of its high surface area, large pores, accessible coordinative unsaturated sites (π-complexation), and π-π stacking action. This ZIF-based magnetic solid-phase extraction (SPE), coupled with gas chromatography/tandem mass spectrometry (GC/MS), was further evaluated for analysis of PAHs from rainwater and air samples of particulate matter less than 2.5μm in diameter (PM2.5). The main effective parameters, including ionic strength, solution pH, extraction time, desorption solvent and desorption time, were investigated, respectively. Under optimized conditions, the developed method based on Fe3O4@PDA/ZIF-7 gave detection limits of 0.71-5.79ng/L, and quantification limits of 2.50-19.2ng/L for PAHs, respectively. The relative standard deviations for intra-day and inter-day analyses were in the range of 3.1-9.1% and 6.1-12.7%, respectively. The PAHs founded in PM2.5 were in the range of 0.40-6.79ng/m(3). Good recoveries (>82%) with low relative standard deviations (≤9.2%) were achieved. This method was demonstrated to be an accurate, convenient and sensitive pretreatment procedure for trace analysis of environmental water and air samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Zeolitic imidazolate framework-coated acoustic sensors for room temperature detection of carbon dioxide and methane.

PubMed

Devkota, Jagannath; Kim, Ki-Joong; Ohodnicki, Paul R; Culp, Jeffrey T; Greve, David W; Lekse, Jonathan W

2018-05-03

The integration of nanoporous materials such as metal organic frameworks (MOFs) with sensitive transducers can result in robust sensing platforms for monitoring gases and chemical vapors for a range of applications. Here, we report on an integration of the zeolitic imidazolate framework - 8 (ZIF-8) MOF with surface acoustic wave (SAW) and thickness shear mode quartz crystal microbalance (QCM) devices to monitor carbon dioxide (CO2) and methane (CH4) under ambient conditions. The MOF was directly coated on the Y-Z LiNbO3 SAW delay lines (operating frequency, f0 = 436 MHz) and AT-cut quartz TSM resonators (resonant frequency, f0 = 9 MHz) and the devices were tested for various gases in N2 under ambient conditions. The devices were able to detect the changes in CO2 or CH4 concentrations with relatively higher sensitivity to CO2, which was due to its higher adsorption potential and heavier molecular weight. The sensors showed full reversibility and repeatability which were attributed to the physisorption of the gases into the MOF and high stability of the devices. Both types of sensors showed linear responses relative to changes in the binary gas compositions thereby allowing to construct calibration curves which correlated well with the expected mass changes in the sorbent layer based on mixed-gas gravimetric adsorption isotherms measured on bulk samples. For 200 nm thick films, the SAW sensitivities to CO2 and CH4 were 1.44 × 10-6/vol% and 8 × 10-8/vol%, respectively, against the QCM sensitivities 0.24 × 10-6/vol% and 1 × 10-8/vol%, respectively, which were evaluated as the fractional change in the signal. The SAW sensors were also evaluated for 100 nm-300 nm thick films, the sensitivities of which were found to increase with the thickness due to the increased number of pores for the adsorption of a larger amount of gases. In addition, the MOF-coated SAW delay lines had a good response in wireless mode, demonstrating their potential to operate remotely for the detection of the gases at emission sites across the energy infrastructure.

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.

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.

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.

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.

Recycling of phenol from aqueous solutions by pervaporation with ZSM-5/PDMS/PVDF hollow fiber composite membrane

NASA Astrophysics Data System (ADS)

Li, Dan; Yao, Jie; Sun, Hao; Liu, Bing; van Agtmaal, Sjack; Feng, Chunhui

2018-01-01

Zeolite (ZSM-5)/polydimethylsiloxane (PDMS)/polyvinylidene fluoride (PVDF) hollow fiber composite membrane was prepared by dynamic negative pressure. The influence of ZSM-5 silanization, coating time and concentration of ZSM-5 on the resulting pervaporation (PV) performance of composite membranes was investigated. The contact angle (CA) was used to measure surface hydrophobic property and it was found that the water contact angle of the membrane was increased significantly from 99° to 132° when the concentration of ZSM-5 increased from 0% to 50%. The morphology of the membrane was characterized by scanning electron microscope (SEM) and those SEM images illustrated that the thickness of the separating layer has obvious differences at varying coating times. Furthermore, the membranes were investigated in PV process to recycle phenol from aqueous solutions as feed mixtures. The impact of phenol concentration in feed, temperature and pressure of penetration side on the PV performance of membrane was studied systematically. When the ZSM-5 concentration was 40% and the coating time was 60 min, separation factor and phenol permeability were 4.56 and 5.78 g/(m2 h), respectively. ZSM-5/PDMS/PVDF membrane significantly improved the recovery efficiency of phenols.

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

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.

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

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.

Adsorption and desorption of sulfur dioxide on novel adsorbents for flue gas desulfurization. Final report, September 1, 1993--August 31, 1994

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

Lin, Y.S.

Dry regenerative sorption processes have recently attracted increasing attention in flue gas desulfurization (FGD) because of their several advantages over the conventional wet-scrubbing processes. Dry sorbents are usually made by coating a transition or alkaline earth metal precursor on the surface of a porous support. Major disadvantages of these sorbents prepared by the conventional methods include relatively poor attrition resistance and low SO{sub 2} sorption capacity. The physical and especially chemical attrition (associated with the sulphation-oxidation-reduction cycles in the process) deteriorates the performance of the sorbents. The low SO{sub 2} sorption capacity is primarily due to the small surface areamore » of the support. Materials with a high surface area are not used as the supports for FGD sorbents because these materials usually are not thermally stable at high temperatures. In the past year, the research supported by Ohio Coal Development Office was focused on synthesis and properties of sol-gel derived alumina and zeolite sorbents with improved properties for FGD. The sol-gel derived alumina has large surface area, mesopore size and excellent mechanical strength. Some alumina-free zeolites not only posses the basic properties required as a sorbent for FGD (hydrophobicity, thermal and chemical stability, mechanical strength) but also have extremely large surface area and selective surface chemistry. The major objectives of this research program were to synthesize the sol-gel derived sorbents and to explore the use of the zeolites either directly as adsorbents or as sorbent support for FGD. The research was aimed at developing novel FGD sorbents possessing better sorption equilibrium and kinetic properties and improved physical and chemical attrition resistance.« less

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.

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.

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.

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.

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.

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.

Research on Molecular Sieve Technology.

ERIC Educational Resources Information Center

Shah, Dhananjai B.; Hayhurst, David T.

1985-01-01

The zeolite synthesis and modification research program at Cleveland State University (Ohio) is described, including program philosophy and objectives, and research facilities. Also considers zeolite synthesis, adsorption on zeolites, kinetics of adsorption, and zeolite catalysis research. (JN)

Electronic Structure of the [Cu 3 (μ-O) 3] 2+ Cluster in Mordenite Zeolite and Its Effects on the Methane to Methanol Oxidation

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

Vogiatzis, Konstantinos D.; Li, Guanna; Hensen, Emiel J. M.

Identifying Cu-exchanged zeolites able to activate C–H bonds and selectively convert methane to methanol is a challenge in the field of biomimetic heterogeneous catalysis. Recent experiments point to the importance of trinuclear [Cu 3(μ-O) 3] 2+ complexes inside the micropores of mordenite (MOR) zeolite for selective oxo-functionalization of methane. The electronic structures of these species, namely, the oxidation state of Cu ions and the reactive character of the oxygen centers, are not yet fully understood. In this study, we performed a detailed analysis of the electronic structure of the [Cu 3(μ-O) 3] 2+ site using multiconfigurational wave-function-based methods and densitymore » functional theory. The calculations reveal that all Cu sites in the cluster are predominantly present in the Cu(II) formal oxidation state with a minor contribution from Cu(III), whereas two out of three oxygen anions possess a radical character. These electronic properties, along with the high accessibility of the out-of-plane oxygen center, make this oxygen the preferred site for the homolytic C–H activation of methane by [Cu 3(μ-O) 3] 2+. These new insights aid in the construction of a theoretical framework for the design of novel catalysts for oxyfunctionalization of natural gas and suggest further spectroscopic examination.« less

Electronic Structure of the [Cu 3 (μ-O) 3] 2+ Cluster in Mordenite Zeolite and Its Effects on the Methane to Methanol Oxidation

DOE PAGES

Vogiatzis, Konstantinos D.; Li, Guanna; Hensen, Emiel J. M.; ...

2017-09-28

Identifying Cu-exchanged zeolites able to activate C–H bonds and selectively convert methane to methanol is a challenge in the field of biomimetic heterogeneous catalysis. Recent experiments point to the importance of trinuclear [Cu 3(μ-O) 3] 2+ complexes inside the micropores of mordenite (MOR) zeolite for selective oxo-functionalization of methane. The electronic structures of these species, namely, the oxidation state of Cu ions and the reactive character of the oxygen centers, are not yet fully understood. In this study, we performed a detailed analysis of the electronic structure of the [Cu 3(μ-O) 3] 2+ site using multiconfigurational wave-function-based methods and densitymore » functional theory. The calculations reveal that all Cu sites in the cluster are predominantly present in the Cu(II) formal oxidation state with a minor contribution from Cu(III), whereas two out of three oxygen anions possess a radical character. These electronic properties, along with the high accessibility of the out-of-plane oxygen center, make this oxygen the preferred site for the homolytic C–H activation of methane by [Cu 3(μ-O) 3] 2+. These new insights aid in the construction of a theoretical framework for the design of novel catalysts for oxyfunctionalization of natural gas and suggest further spectroscopic examination.« less

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.

Effects of zeolites on cultures of marine micro-algae: A brief review.

PubMed

Fachini, Adriano; Vasconcelos, Maria Teresa S D

2006-10-01

The cation-exchange capacity of zeolites is well known and has been increasingly explored in different fields with both economic and environmental successes. In aquatic medium with low salinity, zeolites have found multiple applications. However, a review of the literature on the applications of zeolites in salt waters found relatively few articles, including some recently published papers. The purpose of this review is to present the state-of-the-art on applications of using zeolites for amending the trace elemental contents of salt water as well as the implications of this property for promoting marine micro-algal growth. This paper deals with the following features: Sorption capacity of zeolites including 1. application of zeolites in saltwater, 2. the role of silicon and zeolites on cultures of micro-algae, and 3. the role of organically chelated trace metals. The following competing factors have been identified as effects of zeolites on algal growth in salt water: (i) ammonia decrease: growth inhibition reduced; (ii) macro-nutrients increase, mainly silicon: stimulation of silicon-dependent algae; (iii) trace metals increase (desorption from zeolites) or decrease (adsorption): inhibition or stimulation, depending on the nature of the element and its concentration; and, (iv) changes in the chelating organics exudation: inhibition or stimulation of growth, depending on the (a) nature of the complexed element; (b) bioavailability of the complex; and (c) concentration of the elements simultaneously present in inorganic forms. Zeolites have been capable of stimulating the growth of the silicon-demanding marine micro-algae, like diatoms, mainly because they can act as a silicon buffer in seawater. Zeolites can also influence the yield of non-silicon-demanding algae, because the changes they can cause (liberation and adsorption of trace elements) in the composition of the medium. Zeolites have been capable of stimulating the growth of the marine micro-algae. However, the extent of ion exchange between zeolite and seawater, which conditions the effects, will depend on several factors: (1) initial metal concentration in seawater; (2) levels of trace metals in the zeolites (contaminants); (3) characteristics of the zeolites in terms of both ion-exchange capacity and specific affinities for the different cations; (4) quantity of zeolite per litre of solution; (5) pH and (6) response of the organism in terms of liberation of organic ligands. Therefore, a previous investigation in each particular case is recommended, in order to select the zeolitic characteristics and concentrations that will maximize the algal yield. Stimulation of phytoplankton growth can be economically relevant since phytoplankton constitutes the basis of the marine food webs and is required in fish farming nurseries in the marine aquaculture industry. Zeolites are cheap, only small amounts (few milligrams per liter of culture) are required and the addition of some micro-nutrients may be omitted. Therefore, the inclusion of zeolites in algal cultures in aquaculture may have economic advantages.

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...

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

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.

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.

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.

The Surface Coating of Commercial LiFePO4 by Utilizing ZIF-8 for High Electrochemical Performance Lithium Ion Battery

NASA Astrophysics Data System (ADS)

Xu, XiaoLong; Qi, CongYu; Hao, ZhenDong; Wang, Hao; Jiu, JinTing; Liu, JingBing; Yan, Hui; Suganuma, Katsuaki

2018-03-01

The requirement of energy-storage equipment needs to develop the lithium ion battery (LIB) with high electrochemical performance. The surface modification of commercial LiFePO4 (LFP) by utilizing zeolitic imidazolate frameworks-8 (ZIF-8) offers new possibilities for commercial LFP with high electrochemical performances. In this work, the carbonized ZIF-8 (CZIF-8) was coated on the surface of LFP particles by the in situ growth and carbonization of ZIF-8. Transmission electron microscopy indicates that there is an approximate 10 nm coating layer with metal zinc and graphite-like carbon on the surface of LFP/CZIF-8 sample. The N2 adsorption and desorption isotherm suggests that the coating layer has uniform and simple connecting mesopores. As cathode material, LFP/CZIF-8 cathode-active material delivers a discharge specific capacity of 159.3 mAh g-1 at 0.1C and a discharge specific energy of 141.7 mWh g-1 after 200 cycles at 5.0C (the retention rate is approximate 99%). These results are attributed to the synergy improvement of the conductivity, the lithium ion diffusion coefficient, and the degree of freedom for volume change of LFP/CZIF-8 cathode. This work will contribute to the improvement of the cathode materials of commercial LIB.[Figure not available: see fulltext.

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.

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.

Structural analysis of hierarchically organized zeolites

PubMed Central

Mitchell, Sharon; Pinar, Ana B.; Kenvin, Jeffrey; Crivelli, Paolo; Kärger, Jörg; Pérez-Ramírez, Javier

2015-01-01

Advances in materials synthesis bring about many opportunities for technological applications, but are often accompanied by unprecedented complexity. This is clearly illustrated by the case of hierarchically organized zeolite catalysts, a class of crystalline microporous solids that has been revolutionized by the engineering of multilevel pore architectures, which combine unique chemical functionality with efficient molecular transport. Three key attributes, the crystal, the pore and the active site structure, can be expected to dominate the design process. This review examines the adequacy of the palette of techniques applied to characterize these distinguishing features and their catalytic impact. PMID:26482337

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.

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

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.

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.

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.

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+.

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.

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...

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.

Theoretical Study of the Mechanism Behind the para-Selective Nitration of Toluene in Zeolite H-Beta

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

Andersen, Amity; Govind, Niranjan; Subramanian, Lalitha

Periodic density functional theory calculations were performed to investigate the origin of the favorable para-selective nitration of toluene exhibited by zeolite H-beta with acetyl nitrate nitration agent. Energy calculations were performed for each of the 32 crystallographically unique Bronsted acid sites of a beta polymorph B zeolite unit cell with multiple Bronsted acid sites of comparable stability. However, one particular aluminum T-site with three favorable Bronsted site oxygens embedded in a straight 12-T channel wall provides multiple favorable proton transfer sites. Transition state searches around this aluminum site were performed to determine the barrier to reaction for both para andmore » ortho nitration of toluene. A three-step process was assumed for the nitration of toluene with two organic intermediates: the pi- and sigma-complexes. The rate limiting step is the proton transfer from the sigma-complex to a zeolite Bronsted site. The barrier for this step in ortho nitration is shown to be nearly 2.5 times that in para nitration. This discrepancy appears to be due to steric constraints imposed by the curvature of the large 12-T pore channels of beta and the toluene methyl group in the ortho approach that are not present in the para approach.« less

Hydrogen isotope separation using molecular sieve of synthetic zeolite 3A

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

Kotoh, K.; Kimura, K.; Nakamura, Y.

2008-07-15

It is known that hydrogen isotope molecules can be adsorbed easily onto synthetic zeolite 4A, 5A, and 13X at the liquid-nitrogen temperature of 77.4 K. We show here that hydrogen and deuterium are not adsorptive onto zeolite 3A at the same temperature. This phenomenon is explained by assuming the molecular sieve function in zeolite-3A-crystalline lattice structure. From a series of pseudo-isobaric experiments, it is also shown that the sieving phenomenon appears in a range above 77.4 K. This behavior is interpreted as resulting on the dependence of sieve's mesh size on temperature, where the sieving effect is considered to appearmore » at a certain temperature. In this interpretation, an isotopic difference between hydrogen and deuterium is suggested to exist in the sieving effect appearance temperatures. This is endorsed in the result of pseudo-isobaric experiments. This temperature deference is very significant because that indicates the possibility of an effective method of hydrogen isotope separation. This possibility is verified through an experimental series of adsorption-desorption with a mixture of H{sub 2} and D{sub 2}, where the gas samples adsorbed through the sieve operated at intentionally selected temperatures are isolated and then analyzed. The result demonstrates remarkable values of isotope separation factor. (authors)« less

Cation-exchanged zeolites for the selective oxidation of methane to methanol

DOE PAGES

Kulkarni, Ambarish R.; Zhao, Zhi-Jian; Siahrostami, Samira; ...

2017-10-19

Motivated by the increasing availability of cheap natural gas resources, considerable experimental and computational research efforts have focused on identifying selective catalysts for the direct conversion of methane to methanol. One promising class of catalysts are cation-exchanged zeolites, which have steadily increased in popularity over the past decade. Here, in this article, we first present a broad overview of this field from a conceptual perspective, and highlight the role of theory in developing a molecular-level understanding of the reaction. Next, by performing and analyzing a large database of density functional theory (DFT) calculations for a wide range of transition metalmore » cations, zeolite topologies and active site motifs, we present a unifying picture of the methane activation process in terms of active site stability, C–H bond activation and methanol extraction. Based on the trade-offs of active site stability and reactivity, we propose a framework for identifying new, promising active site motifs in these systems. Further, we show that the high methanol selectivity arises due to the strong binding nature of the C–H activation products. Lastly, using the atomistic and mechanistic insight obtained from these analyses, we summarize the key challenges and future strategies for improving the performance of cation-exchanged zeolites for this industrially relevant conversion.« less

Cation-exchanged zeolites for the selective oxidation of methane to methanol

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

Kulkarni, Ambarish R.; Zhao, Zhi-Jian; Siahrostami, Samira

Motivated by the increasing availability of cheap natural gas resources, considerable experimental and computational research efforts have focused on identifying selective catalysts for the direct conversion of methane to methanol. One promising class of catalysts are cation-exchanged zeolites, which have steadily increased in popularity over the past decade. Here, in this article, we first present a broad overview of this field from a conceptual perspective, and highlight the role of theory in developing a molecular-level understanding of the reaction. Next, by performing and analyzing a large database of density functional theory (DFT) calculations for a wide range of transition metalmore » cations, zeolite topologies and active site motifs, we present a unifying picture of the methane activation process in terms of active site stability, C–H bond activation and methanol extraction. Based on the trade-offs of active site stability and reactivity, we propose a framework for identifying new, promising active site motifs in these systems. Further, we show that the high methanol selectivity arises due to the strong binding nature of the C–H activation products. Lastly, using the atomistic and mechanistic insight obtained from these analyses, we summarize the key challenges and future strategies for improving the performance of cation-exchanged zeolites for this industrially relevant conversion.« less

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.

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...

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

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

Silver-Ion-Exchanged Nanostructured Zeolite X as Antibacterial Agent with Superior Ion Release Kinetics and Efficacy against Methicillin-Resistant Staphylococcus aureus.

PubMed

Chen, Shaojiang; Popovich, John; Iannuzo, Natalie; Haydel, Shelley E; Seo, Dong-Kyun

2017-11-15

As antibiotic resistance continues to be a major public health problem, antimicrobial alternatives have become critically important. Nanostructured zeolites have been considered as an ideal host for improving popular antimicrobial silver-ion-exchanged zeolites, because with very short diffusion path lengths they offer advantages in ion diffusion and release over their conventional microsized zeolite counterparts. Herein, comprehensive studies are reported on materials characteristics, silver-ion release kinetics, and antibacterial properties of silver-ion-exchanged nanostructured zeolite X with comparisons to conventional microsized silver-ion-exchanged zeolite (∼2 μm) as a reference. The nanostructured zeolites are submicrometer-sized aggregates (100-700 nm) made up of primary zeolite particles with an average primary particle size of 24 nm. The silver-ion-exchanged nanostructured zeolite released twice the concentration of silver ions at a rate approximately three times faster than the reference. The material exhibited rapid antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 4 to 16 μg/mL after 24 h exposure in various growth media and a minimum bactericidal concentration (MBC; >99.9% population reduction) of 1 μg/mL after 2 h in water. While high concentrations of silver-ion-exchanged nanostructured zeolite X were ineffective at reducing MRSA biofilm cell viability, efficacy increased at lower concentrations. In consideration of potential medical applications, cytotoxicity of the silver-ion-exchanged nanostructured zeolite X was also investigated. After 4 days of incubation, significant reduction in eukaryotic cell viability was observed only at concentrations 4-16-fold greater than the 24 h MIC, indicating low cytotoxicity of the material. Our results establish silver-ion-exchanged nanostructured zeolites as an effective antibacterial material against dangerous antibiotic-resistant bacteria.

Innovative In-Situ Remediation of Contaminated Sediments for Simultaneous Control of Contamination and Erosion. Part 2

DTIC Science & Technology

2011-10-01

00516 20 Table 10. Partitioning coefficients used in transport modeling. Metal Clinoptilolite Zeolite (ml/g) Phillipsite Zeolite (ml/g) As...3 and 5. Laboratory protocols used for these tests were the same as those used for the previously described zeolite bioassays. The significance...amendments. Two cases were simulated using the 1-dimensional model for clinoptilolite zeolite (ZC) and phillipsite zeolite (ZP). The results of the

[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 fibers. Thus, local and systemic effects of zeolites may be complex and interrelated, and an objective assessment requires appropriate experimental models.

'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

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.

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.

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.

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×yH2O precursor.

Lewis Acid Pairs for the Activation of Biomass-derived Oxygenates in Aqueous Media

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

Roman, Yuriy

2015-09-14

The objective of this project is to understand the mechanistic aspects behind the cooperative activation of oxygenates by catalytic pairs in aqueous media. Specifically, we will investigate how the reactivity of a solid Lewis acid can be modulated by pairing the active site with other catalytic sites at the molecular level, with the ultimate goal of enhancing activation of targeted functional groups. Although unusual catalytic properties have been attributed to the cooperative effects promoted by such catalytic pairs, virtually no studies exist detailing the use heterogeneous water-tolerant Lewis pairs. A main goal of this work is to devise rational pathwaysmore » for the synthesis of porous heterogeneous catalysts featuring isolated Lewis pairs that are active in the transformation of biomass-derived oxygenates in the presence of bulk water. Achieving this technical goal will require closely linking advanced synthesis techniques; detailed kinetic and mechanistic investigations; strict thermodynamic arguments; and comprehensive characterization studies of both materials and reaction intermediates. For the last performance period (2014-2015), two technical aims were pursued: 1) C-C coupling using Lewis acid and base pairs in Lewis acidic zeolites. Tin-, zirconium-, and hafnium containing zeolites (e.g., Sn-, Zr-, and Hf-Beta) are versatile solid Lewis acids that selectively activate carbonyl functional groups. In this aim, we demonstrate that these zeolites catalyze the cross-aldol condensation of aromatic aldehydes with acetone under mild reaction conditions with near quantitative yields. NMR studies with isotopically labeled molecules confirm that acid-base pairs in the Si-O-M framework ensemble promote soft enolization through α-proton abstraction. The Lewis acidic zeolites maintain activity in the presence of water and, unlike traditional base catalysts, in acidic solutions. 2) One-pot synthesis of MWW zeolite nanosheets for activation of bulky substrates. Through post-synthetic modifications, layered zeolite precursors can be transformed into 2-dimensional (2D), zeolites with open architectures. These novel hierarchical microporous/mesoporous materials with exposed active sites can facilitate the conversion of bulky substrates while maintaining higher stability than amorphous mesoporous materials. However, post-synthetic exfoliation techniques are energy intensive, multi-step and require highly alkaline conditions that result in low silica yields and a partially amorphous product. In this aim, we demonstrate an effective one-pot synthesis method to generate exfoliated single-unit-cell thick MWW nanosheets. The new material, named MIT-1, is synthesized using a rationally-designed OSDA and results in a material with high crystallinity, surface area, and acidity that does not require post-synthetic treatments other than calcination. A parametric study of Al, Na, and water content reveals that MIT-1 crystallizes over a wide synthetic window. Characterization data show that MIT-1 has high mesoporosity with an external surface area exceeding 500 m2g-1 and a high external acid site density of 21 x 10-5 mol g-1. Catalytic tests demonstrate that MIT-1 has three-fold higher catalytic activity for the Friedel-Crafts alkylation of benzene with benzyl alcohol as compared to that of other 3D MWW topology zeolites.« less

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.

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.

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.

Chemistry of alkali cation exchanged faujasite and mesoporous NaX using alkyl halides and phosphates

NASA Astrophysics Data System (ADS)

Lee, Min-Hong

The purpose of this work was to increase the reactivity of Faujasite X (NaX) zeolite toward the reactive decontamination of materials subject to nucleophilic attack by means of zeolite cation optimization and by means of the synthesis of mesoporous Faujasite X. Primary alkyl halides and trialkyl phosphates have been the test materials on which the cation-optimized and mesoporous zeolites have been tested. In the alkali cation optimization work, reactions of methyl iodide and 1-chloropropane with alkali metal cation exchanged Faujasite zeolite X were investigated at room temperature. The reactivity of the framework and the product formation were shown to depend on zeolite framework counter-cation. A quantitative study of zeolite product formation has been carried out, primarily using solid-state NMR spectroscopy. Large alkali cations showed preference toward substitution chemistry. In contrast, alkyl halide exposed LiX and NaX zeolites underwent both substitution and elimination. Subsequently introduced water molecules led to hydrolysis of framework species that was sensitive to framework counter-cation. The mesoporous NaX zeolites work undertakes to test whether an improvement in surface chemical reactivity can be achieved by introducing mesopores into the already reactive nucleophilic microporous NaX zeolite. Incorporation of the polydiallyl dimethyl ammonium chloride (PDADMAC) template and the formation of mesopores in Faujasite X zeolite (NaX) were successful and well-characterized. The mesopores are proposed to have occurred from incorporation of the cationic PDADMAC polymer into the zeolite by compensating zeolite framework charge. Subsequent sodium cation exchange of calcined mesoporous NaX was shown to restore the chemical reactivity characteristic of as-synthesized NaX. Trialkyl organophosphorous compounds underwent substitution reactions. The reactivity of both microporous and mesoporous Faujasite zeolite X and the product formation was shown to depend on the length of the alkyl chain. Although introduced mesopores alleviated the limited reagent diffusion to reactive sites due to the microporosity of the NaX zeolites, no marked improvement in the product yields was achieved with either the 1-chloroalkanes or the trialkyl phosphates test compounds, regardless of alkyl chain length. The disappointing results have been attributed to lack of substantial net increase in the numbers of zeolite nucleophilic sites accompanying mesopore introduction.

The Effect of K and Acidity of NiW-Loaded HY Zeolite Catalyst for Selective Ring Opening of 1-Methylnaphthalene.

PubMed

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

2016-05-01

Bi-functional catalysts were prepared using HY zeolites with various SiO2/Al2O3 ratios for acidic function, NiW for metallic function, and K for acidity control. 1-Methylnaphthalene was selected as a model compound for multi-ring aromatics in heavy oil, and its selective ring opening reaction was investigated using the prepared bi-functional catalysts with different levels of acidity in a fixed bed reactor system. In NiW/HY catalysts without K addition, the acidity decreased with the SiO2/Al2O3 mole ratio of the HY zeolite. Ni1.1W1.1/HY(12) catalyst showed the highest acidity but slightly lower yields for the selective ring opening than Ni1.1W1.1/HY(30) catalyst. The acidity of the catalyst seemed to play an important role as the active site for the selective ring opening of 1-methylnaphthalene but there should be some optimum catalyst acidity for the reaction. Catalyst acidity could be controlled between Ni1.1W1.1/HY(12) and Ni1.1W1.1/HY(30) by adding a moderate amount of K to Ni1.1W1.1/HY(12) catalyst. K0.3Ni1.1W1.1/HY(12) catalyst should have the optimum acidity for the selective ring opening. The addition of a moderate amount of K to the NiW/HY catalyst must improve the catalytic performance due to the optimization of catalyst acidity.

Preparation of 13X from Waste Quartz and Photocatalytic Reaction of Methyl Orange on TiO2/ZSM-5, 13X and Y-Zeolite.

PubMed

Wang, Jia-Jie; Jing, You-Hai; Ouyang, Tong; Chang, Chang-Tang

2015-08-01

TiO2 photocatalytic reactions not only remove a variety of organic pollutants via complete mineralization, but also destroy the bacterial cell wall and cell membrane, thus playing an important bactericidal role. However, the post-filtration procedures to separate nanometer-levels of TiO2 and the gradual inactivity of photocatalyst during continuous use are defects that limit its application. In this case, we propose loading TiO2 on zeolite for easy separation and 13X is considered as a promising one. In our study, 13X-zeolite was prepared by a hydrothermal method and the source of Si was extracted from waste quartz sand. For comparison, commercial zeolite with different microporous and mesoporous diameters (ZSM-5 and Y-zeolites) were also used as TiO2 supports. The pore size of the three kinds of zeolites are as follows: Y-zeolite > 13X > ZSM-5. Different TiO2 loading content over ZSM-5, 13X and Y-zeolite were prepared by the sol-gel method. XRD, FTIR, BET, UV-vis, TGA and SEM were used for investigation of material characteristics. In addition, the efficiencies of mineralization and photodegradation were studied in this paper. The effects of the loading ratio of TiO2 over zeolites, initial pH, and concentration on photocatalytic performance are investigated. The relationship between best loading content of TiO2 and pore size of the zeolite was studied. The possible roles of the ZSM-5, 13X-zeolites and Y-zeolites support on the reactions and the possible mechanisms of effects were also explored. The best loading content of TiO2 over ZSM-5, 13X and Y-zeolite was found to be 50 wt%, 12.5 wt% and 7 wt%, respectively. The optimum pH condition is 3 with TiO2 over ZSM-5, 13X-zeolites and Y-zeolites. The results showed that the degradation and mineralization efficiency of 12.5 wt%GT13X (TiO2 over 13X) after 90 min irradiation reached 57.9% and 22.0%, which was better than that of 7 wt%GTYZ (TiO2 over Y-zeolites) while much lower than that of 50 wt%GTZ (TiO2 over ZSM-5). The materials were recycled four times while the degradation was remained at a higher level.

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.

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.

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.

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

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.

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

Electrochemical water splitting using nano-zeolite Y supported tungsten oxide electrocatalysts

NASA Astrophysics Data System (ADS)

Anis, Shaheen Fatima; Hashaikeh, Raed

2018-02-01

Zeolites are often used as supports for metals and metal oxides because of their well-defined microporous structure and high surface area. In this study, nano-zeolite Y (50-150 nm range) and micro-zeolite Y (500-800 nm range) were loaded with WO3, by impregnating the zeolite support with ammonium metatungstate and thermally decomposing the salt thereafter. Two different loadings of WO3 were studied, 3 wt.% and 5 wt.% with respect to the overall catalyst. The prepared catalysts were characterized for their morphology, structure, and surface areas through scanning electron microscope (SEM), XRD, and BET. They were further compared for their electrocatalytic activity for hydrogen evolution reaction (HER) in 0.5 M H2SO4. On comparing the bare micro-zeolite particles with the nano-form, the nano-zeolite Y showed higher currents with comparable overpotentials and lower Tafel slope of 62.36 mV/dec. WO3 loading brought about a change in the electrocatalytic properties of the catalyst. The overpotentials and Tafel slopes were observed to decrease with zeolite-3 wt.% WO3. The smallest overpotential of 60 mV and Tafel slope of 31.9 mV/dec was registered for nano-zeolite with 3 wt.% WO3, while the micro-zeolite gave an overpotential of 370 mV and a Tafel slope of 98.1 mV/dec. It was concluded that even with the same metal oxide loading, nano-zeolite showed superior performance, which is attributed to its size and hence easier escape of hydrogen bubbles from the catalyst.

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.

Reactivity of propene, n-butene, and isobutene in the hydrogen transfer steps of n-hexane cracking over zeolites of different structure

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

Lukyanov, D.B.

The reaction of n-hexane cracking over HZSM-5, HY zeolite and mordenite (HM) was studied in accordance with the procedure of the [beta]-test recently proposed for quantitative characterization of zeolite hydrogen transfer activity. It is shown that this procedure allows one to obtain quantitative data on propene, n-butene, and isobutene reactivities in the hydrogen transfer steps of the reaction. The results demonstrate that in the absence of steric constraints (large pore HY and HM zeolites) isobutene is approximately 5 times more reactive in hydrogen transfer than n-butene. The latter, in turn, is about 1.3 times more reactive than propene. With mediummore » pore HZSM-5, steric inhibition of the hydrogen transfer between n-hexane and isobutene is observed. This results in a sharp decrease in the isobutene reactivity: over HZSM-5 zeolites isobutene is only 1.2 times more reactive in hydrogen transfer than n-butene. On the basis of these data it is concluded that the [beta]-test measures the [open quotes]real[close quotes] hydrogen transfer activity of zeolites, i.e., the activity that summarizes the effects of the acidic and structural properties of zeolites. An attempt is made to estimate the [open quotes]ideal[close quotes] zeolite hydrogen transfer activity, i.e., the activity determined by the zeolite acidic properties only. The estimations obtained show that this activity is approximately 1.8 and 1.6 times higher for HM zeolite in comparison with HZSM-5 and HY zeolites, respectively. 16 refs., 4 figs., 2 tabs.« less

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.

Performance of warm mix asphalt with Buton natural asphalt-rubber and zeolite as an additives

NASA Astrophysics Data System (ADS)

Wahjuningsih, N.; Hadiwardoyo, S. P.; Sumabrata, R. J.; Anis, M.

2018-01-01

The aim of this research is improving of asphalt industry to decrease the fuel consumption by lowering the temperature of mixing and compacting of asphalt mixture. This technology known as Warm Mix Asphalt (WMA). Buton Natural Asphalt Rubber (BNA-R) as a function of the additive has been able to improve the performance of HMA. Zeolit has a function as an additive to lowering the mixing temperature. Aggregate composition using the composition of aggregate grading specifications for airport pavement, with the composition of BNA-R 5% and 10% and Zeolite content of 2%. The mixture have produced Resilient Modulus value by using the Universal Material Testing Apparatus (UMATTA) on optimum bitumen content each of which has been obtained from the Marshall test. Furthermore, the value of permanent deformation of asphalt mixtures tested using Wheel Tracking Machine (WTM). The result shows that BNA-R modified binder for WMA can decrease the rutting potential. The additive of local materials has improved the performance of the WMA for airport pavement with certain restrictions. From this research it is known there have been changes in the characteristics of resilient modulus and permanent deformation due to the addition of BNA-R for type of aggregate composition.

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)

Batch sorption results for neptunium transport through Yucca Mountain tuffs. Yucca Mountain Site Characterization Program milestone 3349

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

Triay, I.R.; Cotter, C.R.; Huddleston, M.H.

1996-09-01

We studied the sorption of neptunium onto tuffs characteristic of the proposed nuclear waste repository at Yucca Mountain, Nevada. The neptunium was in the Np(V) oxidation state under oxidizing conditions in groundwaters from two wells located close to the repository site (J-13 and UE-25 p No.1). We used devitrified, vitric, zeolitic (with emphasis on clinoptilolite-rich samples), and calcite-rich tuffs characteristic of the geology of the site. Neptunium sorbed well onto calcite and calcite-rich tuffs, indicating that a significant amount of neptunium retardation can be expected under fractured-flow scenarios because of calcite coating of the fractures. Neptunium sorption onto clinoptilolite-rich zeoliticmore » tuffs in J-13 well water (pH from 7 to 8.5) was moderate, increased with decreasing pH, and correlated to surface area and amount of clinoptilolite. Neptunium sorbed poorly onto zeolitic tuffs from UE-25 p No.1 groundwater (pH from 7 to 9) and onto devitrified and vitric tuffs from J-13 and UE-25 p No.1 waters (pH from 7 to 9). Iron oxides appeared to be passivated in tuffs, not seeming to contribute to the observed neptunium sorption, even though neptunium sorption onto synthetic iron oxide is significant.« less

Ethanol dehydration to ethylene in a stratified autothermal millisecond reactor.

PubMed

Skinner, Michael J; Michor, Edward L; Fan, Wei; Tsapatsis, Michael; Bhan, Aditya; Schmidt, Lanny D

2011-08-22

The concurrent decomposition and deoxygenation of ethanol was accomplished in a stratified reactor with 50-80 ms contact times. The stratified reactor comprised an upstream oxidation zone that contained Pt-coated Al(2)O(3) beads and a downstream dehydration zone consisting of H-ZSM-5 zeolite films deposited on Al(2)O(3) monoliths. Ethanol conversion, product selectivity, and reactor temperature profiles were measured for a range of fuel:oxygen ratios for two autothermal reactor configurations using two different sacrificial fuel mixtures: a parallel hydrogen-ethanol feed system and a series methane-ethanol feed system. Increasing the amount of oxygen relative to the fuel resulted in a monotonic increase in ethanol conversion in both reaction zones. The majority of the converted carbon was in the form of ethylene, where the ethanol carbon-carbon bonds stayed intact while the oxygen was removed. Over 90% yield of ethylene was achieved by using methane as a sacrificial fuel. These results demonstrate that noble metals can be successfully paired with zeolites to create a stratified autothermal reactor capable of removing oxygen from biomass model compounds in a compact, continuous flow system that can be configured to have multiple feed inputs, depending on process restrictions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance Evaluation of Engineered Structured Sorbents for Atmosphere Revitalization Systems On Board Crewed Space Vehicles and Habitats

NASA Technical Reports Server (NTRS)

Howard, David F.; Perry, Jay L.; Knox, James C.; Junaedi, Christian; Roychoudhury, Subir

2011-01-01

Engineered structured (ES) sorbents are being developed to meet the technical challenges of future crewed space exploration missions. ES sorbents offer the inherent performance and safety attributes of zeolite and other physical adsorbents but with greater structural integrity and process control to improve durability and efficiency over packed beds. ES sorbent techniques that are explored include thermally linked and pressure-swing adsorption beds for water-save dehumidification and sorbent-coated metal meshes for residual drying, trace contaminant control, and carbon dioxide control. Results from sub-scale performance evaluations of a thermally linked pressure-swing adsorbent bed and an integrated sub-scale ES sorbent system are discussed.

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.

Modeling cation/anion-water interactions in functional aluminosilicate structures.

PubMed

Richards, A J; Barnes, P; Collins, D R; Christodoulos, F; Clark, S M

1995-02-01

A need for the computer simulation of hydration/dehydration processes in functional aluminosilicate structures has been noted. Full and realistic simulations of these systems can be somewhat ambitious and require the aid of interactive computer graphics to identify key structural/chemical units, both in the devising of suitable water-ion simulation potentials and in the analysis of hydrogen-bonding schemes in the subsequent simulation studies. In this article, the former is demonstrated by the assembling of a range of essential water-ion potentials. These span the range of formal charges from +4e to -2e, and are evaluated in the context of three types of structure: a porous zeolite, calcium silicate cement, and layered clay. As an example of the latter, the computer graphics output from Monte Carlo computer simulation studies of hydration/dehydration in calcium-zeolite A is presented.

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.

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

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 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...

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.

Chloride Diffusion and Acid Resistance of Concrete Containing Zeolite and Tuff as Partial Replacements of Cement and Sand

PubMed Central

Mohseni, Ehsan; Tang, Waiching; Cui, Hongzhi

2017-01-01

In this paper, the properties of concrete containing zeolite and tuff as partial replacements of cement and sand were studied. The compressive strength, water absorption, chloride ion diffusion and resistance to acid environments of concretes made with zeolite at proportions of 10% and 15% of binder and tuff at ratios of 5%, 10% and 15% of fine aggregate were investigated. The results showed that the compressive strength of samples with zeolite and tuff increased considerably. In general, the concrete strength increased with increasing tuff content, and the strength was further improved when cement was replaced by zeolite. According to the water absorption results, specimens with zeolite showed the lowest water absorption values. With the incorporation of tuff and zeolite, the chloride resistance of specimens was enhanced significantly. In terms of the water absorption and chloride diffusion results, the most favorable replacement of cement and sand was 10% zeolite and 15% tuff, respectively. However, the resistance to acid attack reduced due to the absorbing characteristic and calcareous nature of the tuff. PMID:28772737

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.

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.

[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.

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.

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.

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.

Comparative study of As (III) and Zn (II) removal from aqueous solutions using Philippine natural zeolite and alumina

NASA Astrophysics Data System (ADS)

Olegario-Sanchez, Eleanor; Pelicano, Christian Mark

2017-12-01

Herein, the heavy metal removal efficiency of Philippine natural zeolite is investigated through a comparative study with commercial alumina (Al2O3). XRD results revealed a high purity crystalline γ-Al2O3 and a natural zeolite having clinoptilolite (Na,K,Ca)2-3Al3(Al,Si)2Si13O36.12H2O and mordenite (Ca, Na2, K2)Al2Si10O24.7H2O as primary component minerals. Micro-pores and plate-like structures were observed on the surface of the natural zeolite. The natural zeolite has shown three times higher removal efficiency for Zn2+ ion than alumina. On the other hand, alumina exhibited comparable but smaller removal efficiency for As3+ as with that of natural zeolite. Alumina showed a higher capability of increasing the pH of both solutions compared with the natural zeolite. Based on removal efficiency and adsorbent costs, Philippine natural zeolite could be used as a low-cost alternative for wastewater treatment.

Activated and Micronized Zeolite in the Modulation of Cellular Oxidative Stress in Mexican Smokers: A Randomized Clinical Trial.

PubMed

Atitlán-Gil, Alfonso; Bretón-de la Loza, Martín M; Jiménez-Ortega, José C; Belefant-Miller, Helen; Betanzos-Cabrera, Gabriel

2017-01-01

Activated and micronized zeolites are used as detoxifying agents in humans. Detoxification is attributed to their ability to reduce lipid peroxidation by scavenging free radicals. To evaluate activated and micronized zeolites as modulators of cellular oxidative stress in Mexican smokers without lung diseases. Randomized clinical trial. Subjects were randomly divided into three groups: activated and micronized zeolites, n = 29; vitamin E, an accepted antioxidant, n = 29; and maltodextrin as control, n = 27. Each group received the corresponding supplementation, dissolved in water, once a day for 30 days as follows: activated and micronized zeolites, 5.4 g activated and micronized zeolite; vitamin E, 400 mg D-alpha tocopheryl acetate; and maltodextrin, 250 mg of maltodextrin. The thiobarbituric acid reactive substances assay was used to screen for lipid peroxidation. Catalase activity, plasma antioxidant capacity, and hydrogen peroxide levels were also measured. Results were analyzed by a one-way ANOVA and post hoc test of Bonferroni. Subjects administered activated and micronized zeolites had equivalent antioxidant activities as subjects administered vitamin E. Activated and micronized zeolites may be useful as a modulator of oxidative stress in smokers. However, inclusion of a comparison group of non-smokers would be useful in future studies to assess the degree to which zeolites reverse the oxidant stress.

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.

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).

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

NASA Astrophysics Data System (ADS)

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

2008-12-01

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

Magnetic zeolite NaA: synthesis, characterization based on metakaolin and its application for the removal of Cu2+, Pb2+.

PubMed

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

2013-06-01

The optimum parameters for synthesis of zeolite NaA based on metakaolin were investigated according to results of cation exchange capacity and static water adsorption of all synthesis products and selected X-ray diffraction (XRD). Magnetic zeolite NaA was synthesized by adding Fe3O4 in the precursor of zeolite. Zeolite NaA and magnetic zeolite NaA were characterized with scanning electron microscopy (SEM) and XRD. Magnetic zeolite NaA with different Fe3O4 loadings was prepared and used for removal of heavy metals (Cu(2+), Pb(2+)). The results show the optimum parameters for synthesis zeolite NaA are SiO2/Al2O3=2.3, Na2O/SiO2=1.4, H2O/Na2O=50, crystallization time 8h, crystallization temperature 95 °C. The addition of Fe3O4 makes the NaA zeolite with good magnetic susceptibility and good magnetic stability regardless of the Fe3O4 loading, confirming the considerable separation efficiency. Additionally, Fe3O4 loading had a little effect on removal of heavy metal by magnetic zeolite, however, the adsorption capacity still reaches 2.3 mmol g(-1) for Cu(2+), Pb(2+) with a removal efficiency of over 95% in spite of 4.7% Fe3O4 loading. This indicates magnetic zeolite can be used to remove metal heavy at least Cu(2+), Pb(2+) from water with metallic contaminants and can be separated easily after a magnetic process. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modification of zeolite 4A for use as an adsorbent for glyphosate and as an antibacterial agent for water.

PubMed

Zavareh, Siamak; Farrokhzad, Zahra; Darvishi, Farshad

2018-07-15

The aim of this work was to design a low cost adsorbent for efficient and selective removal of glyphosate from water at neutral pH conditions. For this purpose, zeolite 4A, a locally abundant and cheap mineral material, was ion-exchanged with Cu 2+ to produce Cu-zeolite 4A. The FTIR results revealed that the modification has no important effect on chemical structure of zeolite 4A. After modification, highly crystalline zeolite 4A was converted to amorphous Cu-zeolite 4A according to XRD studies. The SEM images showed spherical-like particles with porous surfaces for Cu-zeolite 4A compared to cubic particles with smooth surfaces for zeolite 4A. Adsorption equilibrium data were well fitted with non-linear forms of Langmuir, Freundlich and Temkin isotherms. The maximum adsorption capacity for Cu-zeolite 4A was calculated to be 112.7 mg g -1 based on the Langmuir model. The adsorption of glyphosate by the modified adsorbent had fast kinetics fitted both pseudo-first-order and pseudo-second-order models. A mechanism based on chemical adsorption was proposed for the removal process. The modified adsorbent had a good selectivity to glyphosate over natural waters common cations and anions. It also showed desired regeneration ability as an important feature for practical uses. The potential use of the developed material as antibacterial agent for water disinfection filters was also investigated by MIC method. Relatively strong antibacterial activity was observed for Cu-zeolite 4A against Gram-positive and Gram-negative model bacteria while zeolite 4A had no antibacterial properties. No release of Cu 2+ to aqueous solutions was detected as unique feature of the developed material. Copyright © 2018 Elsevier Inc. All rights reserved.

Supported Rhenium Complexes: Almost Uniform Rhenium Tricarbonyls Synthesized from CH[subscript 3]Re(CO)[subscript 5] and HY Zeolite

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

Lobo-Lapidus, Rodrigo J.; Gates, Bruce C.

2010-12-07

Supported rhenium complexes were prepared from CH{sub 3}Re(CO){sub 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{sub 3}Re(CO){sub 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 bondedmore » 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 {nu}{sub CO} region of the IR spectrum, indicating highly uniform species. In contrast, the species formed from CH{sub 3}Re(CO){sub 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 {nu}{sub CO} bands in the IR spectra. The results show the importance of zeolite H{sup +} sites for the formation of uniform supported rhenium carbonyls from CH{sub 3}Re(CO){sub 5}; the formation of such uniform complexes did not occur on the NaY zeolite.« less

Hierarchical zeolites from class F coal fly ash

NASA Astrophysics Data System (ADS)

Chitta, Pallavi

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

[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 medium zeolite doses (≤ 10 g · kg⁻¹), while inhibited by high zeolite doses (20 g · kg⁻¹). Compared to ordinary zeolite, the biomass of Chinese cabbage was significantly increased by Nano zeolite, while the exchangeable Cd in soil as well as Cd concentration and Cd accumulation of cabbage were significantly reduced.

Furfural to Furfuryl Alcohol: Computational Study of the Hydrogen Transfer on Lewis Acidic BEA Zeolites and Effects of Cation Exchange and Tetravalent Metal Substitution.

PubMed

Prasertsab, Anittha; Maihom, Thana; Probst, Michael; Wattanakit, Chularat; Limtrakul, Jumras

2018-06-04

The hydrogen transfer of furfural to furfuryl alcohol with i-propanol as the hydrogen source over cation-exchanged Lewis acidic BEA zeolite has been investigated by means of density functional calculations. The reaction proceeds in three steps. First the O-H bond of i-propanol is broken to form a propoxide intermediate. After that, the furylmethoxy intermediate is formed via hydrogen transfer process, and finally furylmethoxy abstracts the proton to form the furfuryl alcohol product. The second step is rate-determining by requiring the highest activation energy (23.8 kcal/mol) if the reaction takes place on Li-Sn-BEA zeolite. We find that the catalytic activity of various cation-exchanged Sn-BEA zeolites is in the order Li-Sn-BEA > Na-Sn-BEA > K-Sn-BEA. The lower activation energy for Li-Sn-BEA compared to Na-Sn-BEA and K-Sn-BEA can be explained by the larger charge transfer from the carbonyl bond to the catalyst, leading to its activation and to the attraction of the hydrogen being transferred. The larger charge transfer in turn is due to the smaller gap between the energies of furfural HOMO and the zeolite LUMO in Li-Sn-BEA, compared to both Na-Sn-BEA and K-Sn-BEA. In a similar way, we also compare the catalytic activity of tetravalent metal centers (Sn, Zr, and Hf) substituted into BEA and find in the order Zr ≥ Hf > Sn, based on activation energies. Finally we investigate statistically which property of the reactants is a suitable descriptor for an approximative prediction of the reaction rate in order to be able to quickly screen promising catalytic materials for this reaction.

RuO2 supported NaY zeolite catalysts: Effect of preparation methods on catalytic performance during aerobic oxidation of benzyl alcohol

NASA Astrophysics Data System (ADS)

Jung, Dasom; Lee, Sunwoo; Na, Kyungsu

2017-10-01

The effects of preparation method for RuO2 supported zeolite catalysts on the catalytic consequences during the aerobic oxidation of benzyl alcohol to benzaldehyde were investigated. Three preparation methods, i.e., (i) simultaneous crystallization of the zeolite framework in the presence of RuCl3 (Ru(SC)/NaY), (ii) post ion-exchange with RuCl3 on the zeolite framework (Ru(IE)/NaY), and (iii) post support of preformed Ru metal nanoparticles on the zeolite surface (Ru(PS)/NaY), were used to construct three different RuO2 supported NaY zeolite catalysts. The catalyst performance was investigated as functions of the reaction time and temperature, in correlation with the structural changes of the catalysts, as analyzed by X-ray diffraction (XRD). The results revealed that the catalytic consequences were dramatically affected by the preparation methods. Although similar conversion was achieved with all three catalysts, the turnover frequency (TOF) differed. The Ru(PS)/NaY catalyst exhibited the highest TOF (33-48 h-1), whereas the other catalysts produced much lower TOFs (9-12 h-1). The Ru(PS)/NaY catalyst also had the highest activation energy (Ea) of 48.39 kJ mol-1, whereas the Ru(SC)/NaY and Ru(IE)/NaY catalysts had Ea values of 18.58 and 24.11 kJ mol-1, respectively. Notably, the Ru(PS)/NaY catalyst yielded a significantly higher pre-exponential factor of 5.22 × 105 h-1, which is about 5 orders of magnitude larger than that of the Ru(SC)/NaY catalyst (7.15 × 100 h-1). This suggests that collision between benzyl alcohol and molecular oxygen was very intensive on the Ru(PS)/NaY catalyst, which explains the higher TOF of the Ru(PS)/NaY catalyst relative to the others in spite of the higher Ea value of the former. In terms of recyclability, the pristine crystallinity of the zeolite framework was maintained in the Ru(SC)/NaY catalyst and the RuO2 phase exhibited an insignificant loss of the initial activity up to three catalytic cycles, whereas Ru(PS)/NaY showed slight loss of activity and Ru(IE)/NaY showed a significant loss of activity due to the disappearance of the RuO2 phase.

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

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.

PEG-template for surface modification of zeolite: A convenient material to the design of polypropylene based composite for packaging films

NASA Astrophysics Data System (ADS)

Toommee, S.; Pratumpong, P.

2018-06-01

Zeolite was successfully modified by conventional synthetic route. Polyethylene glycol was employed for surface modification of zeolite. The surface of zeolite exhibited therefore hydrophobic properties. Less than 5 wt% of modified zeolites with uniform size and shape were integrated into polypropylene matrix. Mechanical properties of composite exhibited the similar trend compare to neat polypropylene. Oxygen transmission rate and water vapor transmission rate were evaluated and it exhibited the strong potential to be a good candidate material in active packaging.

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.

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.

On the reactive occlusion of the (uranium trichloride + lithium chloride + potassium chloride) eutectic salt in zeolite 4A

NASA Astrophysics Data System (ADS)

Lexa, Dusan; Leibowitz, Leonard; Kropf, Jeremy

2000-03-01

The interaction between the (uranium trichloride + lithium chloride + potassium chloride) eutectic salt and zeolite 4A has been studied by temperature-resolved synchrotron powder X-ray diffraction, evolved gas analysis and differential scanning calorimetry, between 300 and 900 K. The onset of salt occlusion by the zeolite has been detected at 450 K. Evidence of a reaction between zeolitic water and uranium trichloride, leading to the formation of uranium dioxide, has appeared at 600 K. The uranium dioxide particle size increases from 2 nm at 600 K to 25 nm at 900 K - an indication of their extra-zeolitic location. No appreciable degradation of the zeolite structure has been observed.

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.

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.

Fabrication of novel chitosan/PAN/magnetic ZSM-5 zeolite coated sponges for absorption of oil from water surfaces.

PubMed

Samadi, Saman; Yazd, Shabnam Sharif; Abdoli, Hossein; Jafari, Pooya; Aliabadi, Majid

2017-12-01

In the present study, the chitosan (bottom layer)/polyacrylonitrile (top layer, PAN) nanofibers were coated on the sponge surface. The synthesized magnetic Fe 3 O 4 - ZSM-5 nanozeolites have been loaded into the chitosan/PAN nanofibers to increase the performance of nanofibers toward absorption of lubricating oil, motor oil and pump oil from water surfaces. Scanning electron microscope (SEM), Transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis were used to characterize the synthesized nanozeolites. The morphology and wettability of nanofibers were determined using SEM and water contact angle tests. The influence of Fe 3 O 4 - ZSM-5 nanozeolite content and chitosan/PAN/Fe 3 O 4 - ZSM-5 nanofiber thickness was evaluated on the potential of sponges for oils absorption. The maximum capacity of the chitosan/PAN/Fe 3 O 4 - ZSM-5 nanofibers coated sponges for absorption of motor oil, lubricating oil and pump oil was found to be 99.4, 95.3 and 88.1g/g, in Fe 3 O 4 - ZSM-5 2wt.% and nanofiber thickness of 12μm (chitosan layer of 2μm and PAN layer of 10μm). The reusability of nanofibrous sponges showed that the hydrophobic chitosan/PAN/Fe 3 O 4 - ZSM-5 nanofibers coated sponges can be easily reused in water-oil separation for many cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

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

Preparation of highly stable zeolite-alginate foam composite for strontium(90Sr) removal from seawater and evaluation of Sr adsorption performance.

PubMed

Hong, Hye-Jin; Kim, Byoung-Gyu; Ryu, Jungho; Park, In-Su; Chung, Kang-Sup; Lee, Sang Moon; Lee, Jin-Bae; Jeong, Hyeon Su; Kim, Hyunchul; Ryu, Taegong

2018-01-01

Alginate bead is a promising strontium (Sr) adsorbent in seawater, but highly concentrated Na ions caused over-swelling and damaged the hydrogel bead. To improve the mechanical stability of alginate bead, flexible foam-type zeolite-alginate composite was synthesized and Sr adsorption performance was evaluated in seawater; 1-10% zeolite immobilized alginate foams were prepared by freeze-dry technique. Immobilization of zeolite into alginate foam converted macro-pores to meso-pores which lead to more compact structure. It resulted in less swollen composite in seawater medium and exhibited highly improved mechanical stability compared with alginate bead. Besides, Sr adsorption efficiency and selectivity were enhanced by immobilization of zeolite in alginate foam due to the increase of Sr binding sites (zeolite). In particular, Sr selectivity against Na was highly improved. The 10% zeolite-alginate foam exhibited a higher log K d of 3.3, while the pure alginate foam exhibited 2.7 in the presence of 0.1 M Na. Finally, in the real seawater, the 10% zeolite-alginate foam exhibited 1.5 times higher Sr adsorption efficiency than the pure alginate foam. This result reveals that zeolite-alginate foam composite is appropriate material for Sr removal in seawater due to its swelling resistance as well as improved Sr adsorption performance in complex media. Copyright © 2017 Elsevier Ltd. 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.

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.

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.

Immobilizing of catalyst using Bayah's natural zeolite to reduce the chemical oxygen demand (COD) and total organic carbon (TOC)

NASA Astrophysics Data System (ADS)

Jayanudin, Kustiningsih, Indar; Sari, Denni Kartika

2017-05-01

Indonesia is rich of natural minerals, many of which had not been widely used. One potential natural mineral is zeolite from Bayah Banten that can be used to support catalyst in the process of waste degradation. The purpose of this research is to characterize the Bayah's zeolite and to figure out the effectiveness of the zeolite as supporting agent to the Fe catalyst in the process of phenol degradation, with the main purposes are to reduce the Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC). This research consists of three steps, activation of natural zeolite using 1M, 2M, and 3M NaOH solution, impregnation process with 0.025M, 0.05 M and 0.075M Fe(NO3)3.9H2O solution, and calcination at 500°C. Bayah's natural zeolite was characterize using Brauner-Emmet-Teller (BET) for its pore area, X-ray Fluorescence (XRF) for analyzing zeolite's component before and after activation process and after impregnation process, and Scanning Electron Microscope (SEM) for analyzing zeolite's morphology. The result showed that the highest pore area was 9Å, Fe metal from Fe(NO3)3.9H2O 0,075 M solution remained in zeolite pore was 7,73%, the reduction of COD and TOC was yielded at H2O2: phenol ratio of 1 : 6.

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.

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.

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.

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

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.

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.

Study on adsorption of rhodamine B onto Beta zeolites by tuning SiO2/Al2O3 ratio.

PubMed

Cheng, Zhi-Lin; Li, Yan-Xiang; Liu, Zan

2018-02-01

The exploration of the relationship between zeolite composition and adsorption performance favored to facilitate its better application in removal of the hazardous substances from water. The adsorption capacity of rhodamine B (RB) onto Beta zeolite from aqueous solution was reported. The relationship between SiO 2 /Al 2 O 3 ratio and adsorption capacity of Beta zeolite for RB was explored. The structure and physical properties of Beta zeolites with various SiO 2 /Al 2 O 3 ratios were determined by XRD, FTIR, TEM, BET, UV-vis and so on characterizations. The adsorption behavior of rhodamine B onto Beta zeolite matched to Langmuir adsorption isotherm and more suitable description for the adsorption kinetics was a pseudo-second-order reaction model. The maximum adsorption capacity of the as-prepared Beta zeolite with SiO 2 /Al 2 O 3 = 18.4 was up to 27.97mg/g. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

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.

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.

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.

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.

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 significantly improve zeolite CEC by bringing the material to near homoionic form. pH and temperature are the critical parameters for using natural zeolites as sorbents. Zeolites should not be used in extremely acidic, neither in extremely basic pH conditions, except for very short times. The exchange of Pb, requires low solution pH, to avoid precipitation but not too low because the H+ are competitive ions for ion exchange; as a result the zeolite CEC related to Pb removal may be downgraded. If pH enters the basic range (e.g. pH>8), more aquatic complexes with lower positive valence than those prevailing in lower pH are produced; these complexes are less attracted by the negative charged zeolitic matrix. Pb uptake is favored at higher temperatures as ion exchange (including the diffusion of exchangeable ions inside the material and the medium, and vice versa) is an endothermic process. With the increase of temperature there is a decrease in hydration of all available exchangeable cations that eases the movement within the channels of the solid matrix. Additionally, the mobility of the potassium ions, present in the zeolitic material, also increases with the temperature resulting in enhanced CEC.

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.

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.

First Principles Simulations of Hydrocarbon Conversion Processes in Functionalized Zeolitic Materials

NASA Astrophysics Data System (ADS)

Mazar, Mark Nickolaus

With increasing demand for chemicals and fuels, and finite traditional crude oil resources, there is a growing need to invent, establish, or optimize chemical processes that convert gasifiable carbon-based feedstocks (e.g., coal, natural gas, oil sands, or biomass) into the needed final products. Catalysis is central to almost every industrial chemical process, including alkane metathesis (AM) and the methanol-to-hydrocarbons (MTH) process, which represent final steps in a sequence of hydrocarbon conversion reactions. An in depth understanding of AM and MTH is essential to the selective production of the desired end products. In this dissertation, ab initio density functional theory simulations provide unique mechanistic and thermodynamic insight of specific elementary steps involved in AM and MTH as performed on zeolite supports. Zeolites have been employed throughout the petroleum industry because of their ability to perform acid-catalyzed reactions (e.g., cracking or MTH). The crystalline structure of zeolites imparts regular microporous networks and, in turn, the selective passage of molecules based on shape and functionality. Many different elements can be grafted onto or substituted into zeolites, resulting in a broad range of catalytic behavior. However, due to the variety of competing and secondary reactions that occur at experimental conditions, it is often difficult to extract quantitative information regarding individual elementary steps. ab initio calculations can be particularly useful for this purpose. Alkane metathesis (i.e., the molecular redistribution or chain length averaging of alkanes) is typically performed by transition metal hydrides on amorphous alumina or silica supports. In Chapter 3, the feasibility of AM in zeolites is assessed by using a grafted Ta-hydride complex to explore the full catalytic cycle in the self-metathesis of ethane. The decomposition of a Ta-metallacyclobutane reaction intermediate that forms during olefin metathesis is responsible for the largest activation energy of the catalytic cycle. This assessment is similar to the findings of alkane metathesis studies on alumina/silica supports and indicates that the entire AM cycle can be performed in zeolites by isolated single-atom transition metal hydrides. Performed over acid form zeolites, MTH is used in the conversion of methanol into a broad range of hydrocarbons, including alkenes, alkanes, and aromatics. For reasons that are not yet rigorously quantified, product selectivities vary dramatically based on the choice of catalyst and reaction conditions. The methylation of species containing double bonds (i.e., co-catalysts) is central to the overall process. Distinct structure-function relationships were found with respect to the elementary steps in the methylation and beta-scission of olefins. In Chapter 4, the role of zeolite topology in the step-wise methylation of ethene by surface methoxides is investigated. Elementary steps are studied across multiple frameworks (i.e., BEA, CHA, FER, MFI, and MOR) constituting a wide variety of confinement environments. The reaction of surface methoxides with ethene is found to require a transition state containing a primary carbocation. The barrier height is found to decrease nearly monotonically with respect to the degree of dispersion interactions stabilizing the primary carbocationic species in the transition state. In addition, quantification of the ``local'' dispersion energy indicates that confinement effects can not be simply correlated to pore size. The beta-scission of olefins plays an important role in the product selectivities of many important chemical processes, including MTH. In Chapter 5, beta-scission modes involving C6 and C8 isomers are investigated at a single, isolated Bronsted acid site within H-ZSM-5. We find that the relative enthalpic barriers of beta-scission elementary steps can be rationalized by the substitution order of the two different carbocationic carbon atoms that are present in the reactant (C+) and transition states (betaC). In fact, the increase in charge required by the betaC atom to go from the physi/chemi-sorbed reactant state to the beta-scission transition state (+0.23e-0.33e) is found to correlate almost linearly with the intrinsic activation energy (89-233 kJ mol-1). The charge of the betaC atom depends, to a large extent, on the substitution order of both the C+ and betaC atoms and, therefore, each beta-scission mode is a sub-category onto itself. Isomerization reactions, which are fast with respect to beta-scission, enable reactant hydrocarbons to explore and find low barrier beta-scission pathways. Selectivities predicted on the basis of the relative barrier heights of beta-scission modes accessible to C6 and C8 species indicate general agreement with experimental observations.

Spaceflight payload design flight experience G-408

NASA Technical Reports Server (NTRS)

Durgin, William W.; Looft, Fred J.; Sacco, Albert, Jr.; Thompson, Robert; Dixon, Anthony G.; Roberti, Dino; Labonte, Robert; Moschini, Larry

1992-01-01

Worcester Polytechnic Institute's first payload of spaceflight experiments flew aboard Columbia, STS-40, during June of 1991 and culminated eight years of work by students and faculty. The Get Away Special (GAS) payload was installed on the GAS bridge assembly at the aft end of the cargo bay behind the Spacelab Life Sciences (SLS-1) laboratory. The Experiments were turned on by astronaut signal after reaching orbit and then functioned for 72 hours. Environmental and experimental measurements were recorded on three cassette tapes which, together with zeolite crystals grown on orbit, formed the basis of subsequent analyses. The experiments were developed over a number of years by undergraduate students meeting their project requirements for graduation. The experiments included zeolite crystal growth, fluid behavior, and microgravity acceleration measurement in addition to environmental data acquisition. Preparation also included structural design, thermal design, payload integration, and experiment control. All of the experiments functioned on orbit and the payload system performed within design estimates.

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,…

Characterization of Water and CO2 Adsorption by Stores 3A Desiccant Samples Using Thermal Gravimetric Analysis and Fourier Transform Infrared Spectroscopy

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

RIVERA, DION A.; ALAM, M. KATHLEEN; MARTIN, LAURA

2003-02-01

Two lots of manufactured Type 3a zeolite samples were compared by TGA/IR analysis. The first lot, obtained from Davidson Chemical, a commercial vendor, was characterized during the previous study cycle for its water and water-plus-CO{sub 2} uptake in order to determine whether CO{sub 2} uptake prevented water adsorption by the zeolite. It was determined that CO{sub 2} did not hamper water adsorption using the Davidson zeolite. CO{sub 2} was found on the zeolite surface at dewpoints below -40 C, however it was found to be reversibly adsorbed. During the course of the previous studies, chemical analyses revealed that the Davidsonmore » 3a zeolite contained calcium in significant quantities, along with the traditional counterions potassium and sodium. Chemical analysis of a Type 3a zeolite sample retrieved from Kansas City (heretofore referred to as the ''Stores 3a'' sample) indicated that the Stores sample was a more traditional Type 3a zeolite, containing no calcium. TGA/IR studies this year focused on obtaining CO{sub 2} and water absorbance data from the Stores 3a zeolite. Within the Stores 3a sample, CO{sub 2} was found to be reversibly absorbed within the sample, but only at and below -60 C with 5% CO{sub 2} loading. The amount of CO{sub 2} observed eluting from the Stores zeolite at this condition was similar to what was observed from the Davidson zeolite sample but with a greater uncertainty in the measured value. The results of the Stores 3a studies are summarized within this report.« less

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

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.

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.

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

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.

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.

Possible Responsibility of Silicone Materials for Degradation of the CO2 Removal System in the International Space Station

NASA Technical Reports Server (NTRS)

Baeza, Mario; Sharma, Hemant; Borrok, David; Ren, Mingua; Pannell, Keith

2011-01-01

From data concerning the degradation of the CO2 removal system in the International Space Station (ISS) two important features were apparent: (1) The atmosphere within the International Space Station (ISS) contained many organic compounds including alcohols, halocarbons, aldehydes, esters, and ketones, inter alia. Various cyclosiloxanes Dn, hexamethylcyclotrisiloxane (D3) and its higher homologs (D4) and (D5) are also present presumably due to offgassing. (2) Screens within the zeolite-containing canisters, used for the removal of CO2, exhibited partial clogging due to zeolitic fragments (dust) along with "sticky" residues, that in toto significantly reduced the efficiency of the CO2 removal process. Samples of the ISS fresh zeolite, used zeolite, filter clogging zeolite particles and residual polymeric materials were examined using, inter alia, NMR, EM and HRSEM. These data were compared to equivalent samples obtained prior and subsequent to Dn polymerization experiments performed in our laboratories using the clean ISS zeolite samples as catalyst. Polysiloxane materials produced were essentially equivalent in the two cases and the EM images demonstrate a remarkable similarity between the ISS filter zeolite samples and the post-polymerization zeolite material from our experiments. In this regard even the changes in the Al/Si ratio from the virgin zeolite material to the filter samples and the post-polymerization laboratory samples samples is noteworthy. This research was supported by a contract from the Boeing Company

Sequestration and disposal of dissolved Cs+ using zeolite 13X

NASA Astrophysics Data System (ADS)

Park, M.; Park, J.; Jeong, H. Y.

2017-12-01

Low-to-intermediate level liquid radioactive wastes (LILLW) typically contain high levels of radioactive 137Cs. Due to the great radiational and thermal stability as well as the high selectivity, zeolite has been commonly utilized to sequester radioactive isotopes from nuclear wastewater effluents. In this study, an Al-rich synthetic zeolite 13X was evaluated for the sorption capacity of Cs+ as a function of pH (4.0-10.5), ionic strength (0.05 and 0.2 M), and initial Cs+ concentration (1×10-6-5×10-3 M). For safe disposal, Cs+-exchanged 13X was both thermally and hydrothermally treated under different temperature and pressure. Subsequently, the resultant materials were examined for the phase transition by X-ray diffraction (XRD) and the local coordination chemistry by X-ray absorption spectroscopy (XAS). Our experimental results will detail the Cs+ sorption behavior by 13X under varying solution compositions. Also, the structural changes of Cs+-exchanged 13X upon thermal and hydrothermal treatment will be delineated to assess the stability of Cs+ in the treated materials.

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

Yang, Dong; Chen, Mingyang; Martinez-Macias, Claudia

In this study, the adsorption of N 2 on structurally well-defined dealuminated HY zeolite-supported iridium diethylene complexes was investigated. Iridium dinitrogen complexes formed when the sample was exposed to N 2 in H 2 at 298 K, as shown by infrared spectra recorded with isotopically labeled N 2. Four supported species formed in various flowing gases: Ir(N 2), Ir(N 2)(N 2), Ir(C 2H 5)(N 2), and Ir(H)(N 2). Their interconversions are summarized in a reaction network, showing, for example, that, in the presence of N 2, Ir(N 2) was the predominant dinitrogen species at temperatures of 273-373 K. Ir(CO)(N 2)more » formed transiently in flowing CO, and in the presence of H 2, rather stable iridium hydride complexes formed. Here, four structural models of each iridium complex bonded at the acidic sites of the zeolite were employed in a computational investigation, showing that the calculated vibrational frequencies agree well with experiment when full calculations are done at the level of density functional theory, independent of the size of the model of the zeolite.« less

Zeolite based microconcentrators for volatile organic compounds sensing at trace-level: fabrication and performance

NASA Astrophysics Data System (ADS)

Almazán, Fernando; Pellejero, Ismael; Morales, Alberto; Urbiztondo, Miguel A.; Sesé, Javier; Pina, M. Pilar; Santamaría, Jesús

2016-08-01

A novel 6-step microfabrication process is proposed in this work to prepare microfluidic devices with integrated zeolite layers. In particular, microfabricated preconcentrators designed for volatile organic compounds (VOC) sensing applications are fully described. The main novelty of this work is the integration of the pure siliceous MFI type zeolite (silicalite-1) polycrystalline layer, i.e. 4.0  ±  0.5 μm thick, as active phase, within the microfabrication process just before the anodic bonding step. Following this new procedure, Si microdevices with an excellent distribution of the adsorbent material, integrated resistive heaters and Pyrex caps have been obtained. Firstly, the microconcentrator performance has been assessed by means of the normal hexane breakthrough curves as a function of sampling and desorption flowrates, temperature and micropreconcentrator design. In a step further, the best preconcentrator device has been tested in combination with downstream Si based microcantilevers deployed as VOC detectors. Thus, a preliminar evaluation of the improvement on detection sensitivity by silicalite-1 based microconcentrators is presented.

X-ray Fluorescence Tomography of Aged Fluid-Catalytic-Cracking Catalyst Particles Reveals Insight into Metal Deposition Processes.

PubMed

Kalirai, Sam; Boesenberg, Ulrike; Falkenberg, Gerald; Meirer, Florian; Weckhuysen, Bert M

2015-11-01

Microprobe X-ray fluorescence tomography was used to investigate metal poison deposition in individual, intact and industrially deactivated fluid catalytic cracking (FCC) particles at two differing catalytic life-stages. 3 D multi-element imaging, at submicron resolution was achieved by using a large-array Maia fluorescence detector. Our results show that Fe, Ni and Ca have significant concentration at the exterior of the FCC catalyst particle and are highly co-localized. As concentrations increase as a function of catalytic life-stage, the deposition profiles of Fe, Ni, and Ca do not change significantly. V has been shown to penetrate deeper into the particle with increasing catalytic age. Although it has been previously suggested that V is responsible for damaging the zeolite components of FCC particles, no spatial correlation was found for V and La, which was used as a marker for the embedded zeolite domains. This suggests that although V is known to be detrimental to zeolites in FCC particles, a preferential interaction does not exist between the two.

Chemical and Biological Resistant Clothing

DTIC Science & Technology

2013-04-01

for DMMP Measurement (Data from Samples with and without the Addition of Particulate Zeolite Sorbents... zeolite -NaA particles (which is a nanoporous zeolite with composition of [Na12(H2O)27][Al12Si12O48]) as dehydrating agent was added to the solution to...adsorb/remove water from the solution completely. The zeolite had a uniform pore diameter of ~0.41 nm, too small to accommodate DMMP molecules

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

Basaldella, E.I.; Bonetto, R.; Tara, J.C.

The synthesis of NaY zeolite was carried out on fired kaolinite microspheres. Changes in porosity, chemical composition, and crystallinity of the solid show zeolite growth on both internal and external microsphere surfaces. It was also observed that, as a consequence of the alkaline treatment, the SiO[sub 2]/Al[sub 2]O[sub 3] ratio in the solid diminishes prior to the appearance of the zeolite, but increases when the zeolite begins to crystallize.

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

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.

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.

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.

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.

The improvement of removal effects on organic pollutants in Wastewater Treatment Plants (WWTP)

NASA Astrophysics Data System (ADS)

Marincas, O.; Petrov, P.; Ternes, T.; Avram, V.; Moldovan, Z.

2009-08-01

Purpose of this study is to improve the efficiency of removal in wastewater treatment plants of some organic pollutants like pharmaceuticals, antioxidants, pesticides (triazines, phenylurea herbicides), personal care products (PCPs) musk fragrances (galaxolide and tonalide) and estrogens using zeolites with excellent absorption capacity. The zeolite selected for all experiments was Szedimentin-MW. The experiment took place in three stages: no zeolite addition, zeolite added at the end of the bioreactor and zeolite added at the start of the bioreactor. The water samples were pre-concentrated with solid phase extraction (SPE) procedure and analyzed with analytical system Gas Chromatography/Mass Spectrometry (GC/MS).

Mechanical Characterization of Nanoporous Thin Films by Nanoindentation and Laser-induced Surface Acoustic Waves

NASA Astrophysics Data System (ADS)

Chow, Gabriel

Thin films represent a critical sector of modern engineering that strives to produce functional coatings at the smallest possible length scales. They appear most commonly in semiconductors where they form the foundation of all electronic circuits, but exist in many other areas to provide mechanical, electrical, chemical, and optical properties. The mechanical characterization of thin films has been a continued challenge due foremost to the length scales involved. However, emerging thin films focusing on materials with significant porosity, complex morphologies, and nanostructured surfaces produce additional difficulties towards mechanical analysis. Nanoindentation has been the dominant thin film mechanical characterization technique for the last decade because of the quick results, wide range of sample applicability, and ease of sample preparation. However, the traditional nanoindentation technique encounters difficulties for thin porous films. For such materials, alternative means of analysis are desirable and the lesser known laser-induced surface acoustic wave technique (LiSAW) shows great potential in this area. This dissertation focuses on studying thin, porous, and nanostructured films by nanoindentation and LiSAW techniques in an effort to directly correlate the two methodologies and to test the limits and applicabilities of each technique on challenging media. The LiSAW technique is particularly useful for thin porous films because unlike indentation, the substrate is properly accounted for in the wave motion analysis and no plastic deformation is necessary. Additionally, the use of lasers for surface acoustic wave generation and detection allows the technique to be fully non-contact. This is desirable in the measurement of thin, delicate, and porous films where physical sample probing may not be feasible. The LiSAW technique is also valuable in overcoming nanoscale roughness, particularly for films that cannot be mechanically polished, since typical SAW wavelengths are micrometers in scale whereas indentation depths are usually confined to the nanometer scale. This dissertation demonstrates the effectiveness of LiSAW on both thin porous layers and rough surfaces and shows the challenges faced by nanoindentation on the same films. Zeolite thin films are studied extensively in this work as a model system because of their porous crystalline framework and enormous economic market. Many types of zeolite exist and their widely varying structures and levels of porosity present a unique opportunity for mechanical characterization. For a fully dense ZSM-5 type zeolite with wear and corrosion resistance properties, nanoindentation was used to compare its mechanical properties to industrial chromium and cadmium films. Through tribological and indentation tests, it was shown that the zeolite film possesses exceptional resilience and hardness therefore demonstrating superior wear resistance to chromium and cadmium. This also highlighted the quality of nanoindentation measurements on thick dense layers where traditional nanoindentation excels. Nanoindentation was then performed on porous and non-porous MFI zeolite films with low-k (low dielectric constant) properties. These films were softer and much thinner than the ZSM-5 coatings resulting in significant substrate effects, evidenced by inflation of the measurements from the hard silicon substrate, during indentation. Such effects were avoided with the LiSAW technique on the same films where properties were readily extracted without complications. An alternative indentation analysis method was demonstrated to produce accurate mechanical measurements in line with the LiSAW results, but the non-traditional technique requires substantial computational intensity. Thus LiSAW was proven to be an accurate and efficient means of mechanical characterization for thin porous layers. The case for LiSAW was further supported by utilizing the technique on a porous nanostructured V2O5 electrode film. The surface roughness, on the same scale as indentation depths, created difficulty in obtaining consistent nanoindentation results. Since the film was too delicate for mechanical polishing, the nanoindentation results possessed a high level of uncertainty. It was demonstrated that the LiSAW technique could extract the mechanical properties from such layers without substrate effects and with higher accuracy than nanoindentation. The research in this dissertation directly demonstrates the areas where nanoindentation excels and the areas where it encounters difficulty. It is shown how the LiSAW technique can be an efficient alternative in the challenging areas through its dependence on bulk dispersive wave motion rather than localized deformation. Thus, LiSAW opens up many avenues towards the mechanical characterization of thin, porous, soft, or rough films. Nanoindentation remains an extremely useful technique for thin film characterization, especially with the alternative analysis adaptation. However, as films continue trending towards smaller length scales, more complex porous morphologies, and engineered nanoscale surfaces, LiSAW may well become an equally valuable and indispensable technique.

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.

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.

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.

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.

Dual-mesoporous ZSM-5 zeolite with highly b-axis-oriented large mesopore channels for the production of benzoin ethyl ether.

PubMed

Zhou, Xiaoxia; Chen, Hangrong; Zhu, Yan; Song, Yudian; Chen, Yu; Wang, Yongxia; Gong, Yun; Zhang, Guobin; Shu, Zhu; Cui, Xiangzhi; Zhao, Jinjin; Shi, Jianlin

2013-07-22

Dual-mesoporous ZSM-5 zeolite with highly b axis oriented large mesopores was synthesized by using nonionic copolymer F127 and cationic surfactant CTAB as co-templates. The product contains two types of mesopores--smaller wormlike ones of 3.3 nm in size and highly oriented larger ones of 30-50 nm in diameter along the b axis--and both of them interpenetrate throughout the zeolite crystals and interconnect with zeolite microporosity. The dual-mesoporous zeolite exhibits excellent catalytic performance in the condensation of benzaldehyde with ethanol and greater than 99 % selectivity for benzoin ethyl ether at room temperature, which can be ascribed to the zeolite lattice structure offering catalytically active sites and the hierarchical and oriented mesoporous structure providing fast access of reactants to these sites in the catalytic reaction. The excellent recyclability and high catalytic stability of the catalyst suggest prospective applications of such unique mesoporous zeolites in the chemical industry. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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...

Planar Solid-Oxide Fuel Cell System Demonstration at UT SimCenter

DTIC Science & Technology

2015-12-09

including metals, carbon, and zeolites , have been proposed for sulfur adsorption performances [9-13]. Nickel and copper supported on activated carbon and... zeolite exhibited effective desulfurization effects for jet fuels [14,15]. Muzic et al. [16] examined the adsorptive desulfurization of three...sulfur by using a nanoporous Ni loaded, Y-type zeolite at ambient conditions. The adsorption capacity of Ni-Y zeolite was 0.84 and 2.31 mg S/g

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

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.

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.

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

Adsorption of Free Fatty Acid (FFA) in Low-Grade Cooking Oil Used Activated Natural Zeolite as Adsorbent

NASA Astrophysics Data System (ADS)

Larasati Tres Ayu Putranti, Monika; Kompiang Wirawan, Sang; Made Bendiyasa, I.

2018-01-01

Adsorption of free fatty acid (FFA) in low-grade cooking oil using active natural zeolite adsorbent was done as an effort to improve the quality of low-grade cooking oil so that it can fulfill the standard of fried oil which has been set on SNI 01-3741-2013. Adsorption was carried out with natural zeolite which activated with HCl and NaOH solution followed by the calcination process. The results showed that the NaOH activated zeolite decreased FFA content in low-grade cooking oil more than the HCl activated natural zeolite, with optimum NaOH concentration was 0.75 M. In the adsorption equilibrium analysis with temperature variation (25 °C, 40 °C, 80 °C ), obtained that adsorption of FFA with NaOH activated natural zeolite follows Adsorption Isotherm Freundlich Model with equilibrium constant value was 20,5873; 0,9629 dan 0,8053.

Sustainable Separations of C4‐Hydrocarbons by Using Microporous Materials

PubMed Central

Gehre, Mascha; Guo, Zhiyong; Rothenberg, Gadi

2017-01-01

Abstract Petrochemical refineries must separate hydrocarbon mixtures on a large scale for the production of fuels and chemicals. Typically, these hydrocarbons are separated by distillation, which is extremely energy intensive. This high energy cost can be mitigated by developing materials that can enable efficient adsorptive separation. In this critical review, the principles of adsorptive separation are outlined, and then the case for C4 separations by using zeolites and metal–organic frameworks (MOFs) is examined. By analyzing both experimental and theoretical studies, the challenges and opportunities in C4 separation are outlined, with a focus on the separation mechanisms and structure–selectivity correlations. Zeolites are commonly used as adsorbents and, in some cases, can separate C4 mixtures well. The pore sizes of eight‐membered‐ring zeolites, for example, are in the order of the kinetic diameters of C4 isomers. Although zeolites have the advantage of a rigid and highly stable structure, this is often difficult to functionalize. MOFs are attractive candidates for hydrocarbon separation because their pores can be tailored to optimize the adsorbate–adsorbent interactions. MOF‐5 and ZIF‐7 show promising results in separating all C4 isomers, but breakthrough experiments under industrial conditions are needed to confirm these results. Moreover, the flexibility of the MOF structures could hamper their application under industrial conditions. Adsorptive separation is a promising viable alternative and it is likely to play an increasingly important role in tomorrow's refineries. PMID:28621064

Theoretical study on the reaction mechanism of hydrogenation of furfural to furfuryl alcohol on Lewis acidic BEA zeolites: effects of defect structure and tetravalent metals substitution.

PubMed

Injongkol, Yuwanda; Maihom, Thana; Treesukul, Piti; Sirijaraensre, Jakkapan; Boekfa, Bundet; Limtrakul, Jumras

2017-09-13

Furfural acquired from agricultural sources is receiving extensive attention in the petrochemical industry as it offers an alternative route to generate more valuable hydrocarbon compounds. Herein, we investigate the furfural hydrogenation to furfuryl alcohol catalyzed by Lewis acidic BEA zeolites at the molecular level by means of the M06-L density functional theory. The mechanistic pictures in the catalytic procedure are revealed. The possible reaction pathways are considered to proceed via either concerted or stepwise mechanisms. With the contribution of zeolite oxygen bridging for the H-H splitting, the rate determining step activation barrier for the stepwise mechanism is 14.7 kcal mol -1 lower than that for the concerted mechanism. The stepwise reaction therefore seems to be favored compared to the concerted one. The catalytic effect of the defect zeolite framework on the stepwise mechanism is also investigated. The activation energy for the stepwise rate-determining step over this site is significantly lower than the corresponding step over the perfect one by 14.1 kcal mol -1 . Finally, the catalytic activity of tetravalent metal centers (Sn, Ge, Zr and Hf) substituted in BEA is also preliminarily compared and it is found to follow the order of Hf > Zr > Sn > Ge based on activation energies and the reaction rate. The difference in the activation energy can be traced back to the difference in the charge transfer from the catalytic site to the adsorbed molecules.

Ab initio structure determination and quantitative disorder analysis on nanoparticles by electron diffraction tomography.

PubMed

Krysiak, Yaşar; Barton, Bastian; Marler, Bernd; Neder, Reinhard B; Kolb, Ute

2018-03-01

Nanoscaled porous materials such as zeolites have attracted substantial attention in industry due to their catalytic activity, and their performance in sorption and separation processes. In order to understand the properties of such materials, current research focuses increasingly on the determination of structural features beyond the averaged crystal structure. Small particle sizes, various types of disorder and intergrown structures render the description of structures at atomic level by standard crystallographic methods difficult. This paper reports the characterization of a strongly disordered zeolite structure, using a combination of electron exit-wave reconstruction, automated diffraction tomography (ADT), crystal disorder modelling and electron diffraction simulations. Zeolite beta was chosen for a proof-of-principle study of the techniques, because it consists of two different intergrown polymorphs that are built from identical layer types but with different stacking sequences. Imaging of the projected inner Coulomb potential of zeolite beta crystals shows the intergrowth of the polymorphs BEA and BEB. The structures of BEA as well as BEB could be extracted from one single ADT data set using direct methods. A ratio for BEA/BEB = 48:52 was determined by comparison of the reconstructed reciprocal space based on ADT data with simulated electron diffraction data for virtual nanocrystals, built with different ratios of BEA/BEB. In this way, it is demonstrated that this smart interplay of the above-mentioned techniques allows the elaboration of the real structures of functional materials in detail - even if they possess a severely disordered structure.

Sustainable Separations of C4 -Hydrocarbons by Using Microporous Materials.

PubMed

Gehre, Mascha; Guo, Zhiyong; Rothenberg, Gadi; Tanase, Stefania

2017-10-23

Petrochemical refineries must separate hydrocarbon mixtures on a large scale for the production of fuels and chemicals. Typically, these hydrocarbons are separated by distillation, which is extremely energy intensive. This high energy cost can be mitigated by developing materials that can enable efficient adsorptive separation. In this critical review, the principles of adsorptive separation are outlined, and then the case for C 4 separations by using zeolites and metal-organic frameworks (MOFs) is examined. By analyzing both experimental and theoretical studies, the challenges and opportunities in C 4 separation are outlined, with a focus on the separation mechanisms and structure-selectivity correlations. Zeolites are commonly used as adsorbents and, in some cases, can separate C 4 mixtures well. The pore sizes of eight-membered-ring zeolites, for example, are in the order of the kinetic diameters of C 4 isomers. Although zeolites have the advantage of a rigid and highly stable structure, this is often difficult to functionalize. MOFs are attractive candidates for hydrocarbon separation because their pores can be tailored to optimize the adsorbate-adsorbent interactions. MOF-5 and ZIF-7 show promising results in separating all C 4 isomers, but breakthrough experiments under industrial conditions are needed to confirm these results. Moreover, the flexibility of the MOF structures could hamper their application under industrial conditions. Adsorptive separation is a promising viable alternative and it is likely to play an increasingly important role in tomorrow's refineries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Feasible conversion of solid waste bauxite tailings into highly crystalline 4A zeolite with valuable application

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

Ma, Dongyang; Wang, Zhendong; Guo, Min

2014-11-15

Highlights: • Concept to convert waste to valuable product is carried out in this study. • An industrially feasible and cost-effective approach was developed and optimized. • Highly crystalline and well-defined zeolite was produced under moderate conditions. • The zeolite derived from the bauxite tailings displayed high ion exchange capacity. • Bauxite tailings have potential application in heavy metal ions adsorbent. - Abstract: Bauxite tailings are a major type of solid wastes generated in the flotation process. The waste by-products caused significant environmental impact. To lessen this hazardous effect from poisonous mine tailings, a feasible and cost-effective solution was conceivedmore » and implemented. Our approach focused on reutilization of the bauxite tailings by converting it to 4A zeolite for reuse in diverse applications. Three steps were involved in the bauxite conversion: wet-chemistry, alkali fusion, and crystallization to remove impurities and to prepare porous 4A zeolite. It was found that the cubic 4A zeolite was single phase, in high purity, with high crystallinity and well-defined structure. Importantly, the 4A zeolite displayed maximum calcium ion exchange capacity averaged at 296 mg CaCO{sub 3}/g, comparable to commercially-available zeolite (310 mg CaCO{sub 3}/g) exchange capacity. Base on the optimal synthesis condition, the reaction yield of zeolite 4A from bauxite tailings achieved to about 38.43%, hence, this study will provide a new paradigm for remediation of bauxite tailings, further mitigating the environmental and health care concerns, particularly in the mainland of PR China.« less

Synthesis of zeolites Na-A and Na-X from tablet compressed and calcinated coal fly ash

NASA Astrophysics Data System (ADS)

Hu, Tao; Gao, Wenyan; Liu, Xin; Zhang, Yifu; Meng, Changgong

2017-10-01

Zeolites Na-A and Na-X are important synthetic zeolites widely used for separation and adsorption in industry. It is of great significance to develop energy-efficient routines that can synthesize zeolites Na-A and Na-X from low-cost raw materials. Coal fly ash (CFA) is the major residue from the combustion of coal and biomass containing more than 85% SiO2 and Al2O3, which can readily replace the conventionally used sodium silicate and aluminate for zeolite synthesis. We used Na2CO3 to replace the expensive NaOH used for the calcination of CFA and showed that tablet compression can enhance the contact with Na2CO3 for the activation of CFA through calcination for the synthesis of zeolites Na-A and Na-X under mild conditions. We optimized the control variables for zeolite synthesis and showed that phase-pure zeolite Na-A can be synthesized with CFA at reactant molar ratio, hydrothermal reaction temperature and reaction time of 1.3Na2O: 0.6Al2O3: 1SiO2: 38H2O at 80°C for 6 h, respectively, while phase-pure zeolite Na-X can be synthesized at 2.2Na2O: 0.2Al2O3: 1SiO2: 88H2O at 100°C for 8 h, respectively. The composition, morphology, specific surface area, vibration spectrum and thermogravimetry of synthesized Na-A and Na-X were further characterized.

Effect of the Organic Loading Rate Increase and the Presence of Zeolite on Microbial Community Composition and Process Stability During Anaerobic Digestion of Chicken Wastes.

PubMed

Ziganshina, Elvira E; Belostotskiy, Dmitry E; Ilinskaya, Olga N; Boulygina, Eugenia A; Grigoryeva, Tatiana V; Ziganshin, Ayrat M

2015-11-01

This study investigates the effect of the organic loading rate (OLR) increase from 1.0 to 3.5 g VS L(-1) day(-1) at constant hydraulic retention time (HRT) of 35 days on anaerobic reactors' performance and microbial diversity during mesophilic anaerobic digestion of ammonium-rich chicken wastes in the absence/presence of zeolite. The effects of anaerobic process parameters on microbial community structure and dynamics were evaluated using a 16S ribosomal RNA gene-based pyrosequencing approach. Maximum 12 % of the total ammonia nitrogen (TAN) was efficiently removed by zeolite in the fixed zeolite reactor (day 87). In addition, volatile fatty acids (VFA) in the fixed zeolite reactor accumulated in lower concentrations at high OLR of 3.2-3.5 g VS L(-1) day(-1). Microbial communities in the fixed zeolite reactor and reactor without zeolite were dominated by various members of Bacteroidales and Methanobacterium sp. at moderate TAN and VFA levels. The increase of the OLR accompanied by TAN and VFA accumulation and increase in pH led to the predominance of representatives of the family Erysipelotrichaceae and genera Clostridium and Methanosarcina. Methanosarcina sp. reached relative abundances of 94 and 57 % in the fixed zeolite reactor and reactor without zeolite at the end of the experimental period, respectively. In addition, the diminution of Synergistaceae and Crenarchaeota and increase in the abundance of Acholeplasmataceae in parallel with the increase of TAN, VFA, and pH values were observed.

Changing the characteristics and properties of zeolite Y and nano-anatase in the formation of a nano-anatase/Y composite with improved photocatalytic and adsorption properties

NASA Astrophysics Data System (ADS)

Domoroshchina, E. N.; Chernyshev, V. V.; Kuz'micheva, G. M.; Dorokhov, A. V.; Pirutko, L. V.; Kravchenko, G. V.; Chumakov, R. B.

2018-02-01

Zeolite Y and the NTD/Y nanocomposite, which were synthesized in situ (the addition of zeolite Y to the reaction mixture in the course of the synthesis of NTD by the sulfate method), were studied by a variety of methods. The decrease in the particle size (scanning electron microscopy) and the water content in pores (X-ray powder diffraction study, the full-profile Rietveld method, IR spectroscopy, differential scanning calorimetry), the increase in OH groups content and the decrease in the water content on the surface of zeolite (X-ray photoelectron spectroscopy) in the composition of NTD/Y compared to the initial zeolite Y were all established. A larger specific surface area of NTD/Y (Brunauer-Emmet-Teller method) compared to the initial zeolite Y is due to the fact that zeolite Y in the nanocomposite contains a smaller amount of water because of the synthesis conditions and the presence of nanocrystalline NTD on the surface of zeolite particles. It was found that NTD/Y nanocomposite exhibits a higher photocatalytic activity in the model decomposition reaction of methyl orange under UV and adsorption capacity for the extraction of P(V) and As(V) ions from aqueous media compared to the initial zeolite and pure NTD obtained under the same conditions, which differs from NTD/Y by the larger particle size, the smaller specific surface and the smaller content of OH groups and water on the surface. The role of Bronsted and Lewis centers in the realization of properties is discussed.

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.

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 ...

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 copper (II) ion from aqueous solution using zeolite Y synthesized from rice husk ash: Equilibrium and kinetic study

NASA Astrophysics Data System (ADS)

Tuyen, Nguyen Thi Kim; Nhan, Do Nguyen Thanh; Nhat, Trieu Thi; An, Ngo Thanh; Long, Nguyen Quang

2017-09-01

Zeolite Y was synthesized from silica of rice-husk ash using hydrothermal process. The crystalline structure FAU of zeolite Y was characterized by X-ray diffraction (XRD). Surface's area of the catalyst was determined by physic-adsorption method using BET model. The zeolite was examined for possibility of Cu2+ adsorbent by an ion-exchange mechanism. Various adsorption isotherm models, such as Langmuir, Freundlich and Dubinin-Radushkevich were tested for equilibrium study. The integration method was applied to find out the possible kinetic equation of the Cu2+ adsorption on the zeolite Y which obtained from cheap and locally available rice husk ash.

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.

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.

Preparation and photoelectrocatalytic performance of N-doped TiO2/NaY zeolite membrane composite electrode material.

PubMed

Cheng, Zhi-Lin; Han, Shuai

2016-01-01

A novel composite electrode material based on a N-doped TiO2-loaded NaY zeolite membrane (N-doped TiO2/NaY zeolite membrane) for photoelectrocatalysis was presented. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) characterization techniques were used to analyze the structure of the N-doped TiO2/NaY zeolite membrane. The XRD and SEM results verified that the N-doped TiO2 nanoparticles with the size of ca. 20 nm have been successfully loaded on the porous stainless steel-supported NaY zeolite membrane. The UV-vis result showed that the N-doped TiO2/NaY zeolite membrane exhibited a more obvious red-shift than that of N-TiO2 nanoparticles. The XPS characterization revealed that the doping of N element into TiO2 was successfully achieved. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane composite electrode material was evaluated by phenol removal and also the effects of reaction conditions on the catalytic performance were investigated. Owing to exhibiting an excellent catalytic activity and good recycling stability, the N-doped TiO2/NaY zeolite membrane composite electrode material was of promising application for photoelectrocatalysis in wastewater treatment.

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.

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.

Improving Ammonium and Nitrate Release from Urea Using Clinoptilolite Zeolite and Compost Produced from Agricultural Wastes

PubMed Central

Omar, Latifah; Ahmed, Osumanu Haruna; Majid, Nik Muhamad Ab.

2015-01-01

Improper use of urea may cause environmental pollution through NH3 volatilization and NO3 − leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4 + and NO3 − release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4 + and NO3 − losses from urea. Bekenu Series soil (Typic Paleudults) was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH4 + and NO3 − release from urea (soil incubation study) compared with urea alone, thus reducing leaching of these ions. Ammonium and NO3 − leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH4 + retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. These observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH4 + and NO3 − release from urea. PMID:25793220

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.

The effect of positioning cations on acidity and stability of the framework structure of Y zeolite

PubMed Central

Deng, Changshun; Zhang, Junji; Dong, Lihui; Huang, Meina; Bin Li; Jin, Guangzhou; Gao, Junbin; Zhang, Feiyue; Fan, Minguang; Zhang, Luoming; Gong, Yanjun

2016-01-01

The investigation on the modification of NaY zeolite on LaHY and AEHY (AE refers Ca and Sr and the molar ratio of Ca and Sr is 1:1) zeolites was proformed by XRD, N2-physisorption (BET), XRF, XPS, NH3-TPD, Py-IR, hydrothermal stability, and catalytic cracking test. These results indicate that HY zeolite with ultra low content Na can be obtained from NaY zeolite through four exchange four calcination method. The positioning capability of La3+ in sodalite cage is much better than that of AE2+ and about 12 La3+ can be well coordinated in sodalite cages of one unit cell of Y zeolite. Appropriate acid amount and strength favor the formation of propylene and La3+ is more suitable for the catalytic cracking of cyclohexane than that of AE2+. Our results not only elaborate the variation of the strong and weak acid sites as well as the Brönsted and Lewis acid sites with the change of exchanged ion content but also explore the influence of hydrothermal aging of LaHY and AEHY zeolites and find the optimum ion exchange content for the most reserved acid sites. At last, the coordination state and stabilization of ion exchanged Y zeolites were discussed in detail. PMID:26987306

Removal of ammonia nitrogen from leachate of Muribeca municipal solid waste landfill, Pernambuco, Brazil, using natural zeolite as part of a biochemical system.

PubMed

Lins, Cecilia Maria M S; Alves, Maria Cristina M; Campos, Juacyara C; Silva, Fabrícia Maria S; Jucá, José Fernando T; Lins, Eduardo Antonio M

2015-01-01

The inadequate disposal of leachate is one of the key factors in the environmental impact of urban solid waste landfills in Brazil. Among the compounds present in the leachates from Brazilian landfills, ammonia nitrogen is notable for its high concentrations. The purpose of this study was to assess the efficiency of a permeable reactive barrier filled with a natural zeolite, which is part of a biochemical system for the tertiary treatment of the leachate from Muribeca Municipal Solid Waste Landfill in Pernambuco, Brazil, to reduce its ammonia nitrogen concentration. This investigation initially consisted of kinetic studies and batch equilibrium tests on the natural zeolite to construct the sorption isotherms, which showed a high sorption capacity, with an average of 12.4 mg NH4+.L(-1), a value close to the sorption rates found for the aqueous ammonium chloride solution. A permeable reactive barrier consisting of natural zeolite, as simulated by the column test, was efficient in removing the ammonia nitrogen present in the leachate pretreated with calcium hydroxide. Nevertheless, the regenerated zeolite did not satisfactorily maintain the sorption properties of the natural zeolite, and an analysis of their cation-exchange properties showed a reduced capacity of 54 meq per 100 g for the regenerated zeolite compared to 150 meq per 100 g for the natural zeolite.

New approach for determination of the influence of long-range order and selected ring oscillations on IR spectra in zeolites

NASA Astrophysics Data System (ADS)

Mikuła, Andrzej; Król, Magdalena; Mozgawa, Włodzimierz; Koleżyński, Andrzej

2018-04-01

Vibrational spectroscopy can be considered as one of the most important methods used for structural characterization of various porous aluminosilicate materials, including zeolites. On the other hand, vibrational spectra of zeolites are still difficult to interpret, particularly in the pseudolattice region, where bands related to ring oscillations can be observed. Using combination of theoretical and computational approach, a detailed analysis of these regions of spectra is possible; such analysis should be, however, carried out employing models with different level of complexity and simultaneously the same theory level. In this work, an attempt was made to identify ring oscillations in vibrational spectra of selected zeolite structures. A series of ab initio calculations focused on S4R, S6R, and as a novelty, 5-1 isolated clusters, as well as periodic siliceous frameworks built from those building units (ferrierite (FER), mordenite (MOR) and heulandite (HEU) type) have been carried out. Due to the hierarchical structure of zeolite frameworks it can be expected that the total envelope of the zeolite spectra should be with good accuracy a sum of the spectra of structural elements that build each zeolite framework. Based on the results of HF calculations, normal vibrations have been visualized and detailed analysis of pseudolattice range of resulting theoretical spectra have been carried out. Obtained results have been applied for interpretation of experimental spectra of selected zeolites.

CuY zeolite catalysts prepared by ultrasonication-assisted ion-exchange for oxidative carbonylation of methanol to dimethyl carbonate.

PubMed

Woo, Je-Min; Seo, Jung Yoon; Kim, Hyunuk; Lee, Dong-Ho; Park, Young Cheol; Yi, Chang-Keun; Park, Yeong Seong; Moon, Jong-Ho

2018-06-01

The influence of ultrasonication treatment on the catalytic performance of CuY zeolite catalysts was investigated for the liquid-phase oxidative carbonylation of methanol to dimethyl carbonate (DMC). The deammoniation method of NH 4 Y into HY zeolites was optimized and characterized by elemental analyzer, derivative thermogravimetry, Brunauer-Emmett-Teller (BET) analyzer, and powder X-ray diffractometry, revealing that the HY zeolite deammoniated at 400 °C presented the highest surface area, complete ammonium/proton ion exchange, and no structure collapse, rendering it the best support from all the prepared zeolites. CuY zeolites were prepared via aqueous phase ion exchange with the aid of ultrasonication. Upon ultrasonication, the Cu + active centers were uniformly dispersed in the Y zeolites, penetrating the core of the zeolite particles in a very short time. In addition to enhancing the Cu dispersity, the ultrasonication treatment influenced the BET surface area, acid amount, Cu + /Cu 2+ ratio, and also had a relatively small impact on the Cu loading. Consequently, adequate exposure to ultrasonication was able to increase the conversion rate of methanol into dimethyl carbonate up to 11.4% with a comparable DMC selectivity of 23.7%. This methanol conversion is 2.65 times higher than that obtained without the ultrasonication treatment. Copyright © 2018 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 other zeolites. To the best of our knowledge, there is no report on the synthesis of a Bikitaite zeolite by sonochemical method for H 2 storage. Copyright © 2016. Published by Elsevier B.V.

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.

Recommended nomenclature for zeolite minerals: report of the subcommittee on zeolites of the International Mineralogical Association, Commission of New Minerals and Mineral Names

USGS Publications Warehouse

Coombs, D.S.; Alberti, A.; Armbruster, T.; Artioli, G.; Colella, C.; Galli, E.; Grice, Joel D.; Liebau, F.; Mandarino, J.A.; Minato, H.; Nickel, E.H.; Passaglia, E.; Peacor, D.R.; Quartieri, S.; Rinaldi, R.; Ross, M.; Sheppard, R.A.; Tillmanns, E.; Vezzalini, G.

1998-01-01

This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association Commission of New Minerals and Mineral Names. In a working definition of a zeolite mineral used for review, interrupted tetrahedral framework structures are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is allowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundance in atomic proportions. To name these, the appropriate chemical symbol is attached by a hyphen to the series name as a suffix except for the names harmotome, pollucite and wairakite in the phillipsite and analcime series. Differences in space-group symmetry and in order-disorder relationships in zeolites having the same topologically distinctive framework do not in general provide adequate grounds for recognition of separate species. Zeolite species are not to be distinguished solely on Si:Al ratio except for heulandite (Si:Al < 4.0) and clinoptilolite (Si:Al ??? 4.0). Dehydration, partial hydration, and over-hydration are not sufficient grounds for the recognition of separate species of zeolites. Use of the term 'ideal formula' should be avoided in referring to a simplified or averaged formula of a zeolite. Newly recognized species in compositional series are as follows: brewsterite-Sr.-Ba: chabazite-Ca.-Na.-K; clinoptilolite-K, -Na, -Ca: dachiardite-Ca, -Na; erionite-K, -Ca: faujasite-Na, -Ca, -Na: paulingite-K. -Ca; phillipsite-Na, -Ca, -Ka; stilbite-Ca, -Na. Key references, type locality, origin of name, chemical data. IZA structure-type symbols, space-group symmetry; unit-cell dimensions, and comments on structure are listed for 13 compositional series, 82 accepted zeolite mineral species, and three of doubtful status. Herschelite, leonhardite, svetlozarite, and wellsite are discredited as mineral species names. Obsolete and discredited names are listed.

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 related to the treatment with the Ag-zeolite product.

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 chemical activation process was most suitable to produce the immobilization media from Lampung natural zeolite for POME waste treatment

Feasible conversion of solid waste bauxite tailings into highly crystalline 4A zeolite with valuable application.

PubMed

Ma, Dongyang; Wang, Zhendong; Guo, Min; Zhang, Mei; Liu, Jingbo

2014-11-01

Bauxite tailings are a major type of solid wastes generated in the flotation process. The waste by-products caused significant environmental impact. To lessen this hazardous effect from poisonous mine tailings, a feasible and cost-effective solution was conceived and implemented. Our approach focused on reutilization of the bauxite tailings by converting it to 4A zeolite for reuse in diverse applications. Three steps were involved in the bauxite conversion: wet-chemistry, alkali fusion, and crystallization to remove impurities and to prepare porous 4A zeolite. It was found that the cubic 4A zeolite was single phase, in high purity, with high crystallinity and well-defined structure. Importantly, the 4A zeolite displayed maximum calcium ion exchange capacity averaged at 296 mg CaCO3/g, comparable to commercially-available zeolite (310 mg CaCO3/g) exchange capacity. Base on the optimal synthesis condition, the reaction yield of zeolite 4A from bauxite tailings achieved to about 38.43%, hence, this study will provide a new paradigm for remediation of bauxite tailings, further mitigating the environmental and health care concerns, particularly in the mainland of PR China. Copyright © 2014 Elsevier Ltd. All rights reserved.

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)).

The effect of zeolite treatment by acids on sodium adsorption ratio of coal seam gas water.

PubMed

Wang, Xiaoyu; Ozdemir, Orhan; Hampton, Marc A; Nguyen, Anh V; Do, Duong D

2012-10-15

Many coal seam gas (CSG) waters contain a sodium ion concentration which is too high relative to calcium and magnesium ions for environment acceptance. Natural zeolites can be used as a cheap and effective method to control sodium adsorption ratio (SAR, which is a measure of the relative preponderance of sodium to calcium and magnesium) due to its high cation exchange capacity. In this study, a natural zeolite from Queensland was examined for its potential to treat CSG water to remove sodium ions to lower SAR and reduce the pH value. The results demonstrate that acid activated zeolite at 30%wt solid ratio can reduce the sodium content from 563.0 to 182.7 ppm; the pH from 8.74 to 6.95; and SAR from 70.3 to 18.5. Based on the results of the batch experiments, the sodium adsorption capacity of the acid-treated zeolite is three times greater than that of the untreated zeolite. Both the untreated and acid-treated zeolite samples were characterized using zeta potential, surface characterization, DTA/TG and particle size distribution in order to explain their adsorption behaviours. Copyright © 2012 Elsevier Ltd. All rights reserved.

Application of zeolitic material synthesized from thermally treated sediment to the removal of trivalent chromium from wastewater.

PubMed

Guan, Qingyu; Wu, Deyi; Lin, Yan; Chen, Xuechu; Wang, Xinze; Li, Chunjie; He, Shengbing; Kong, Hainan

2009-08-15

Zeolitic materials were synthesized from thermally treated sediment by alkali treatment using different NaOH/sediment ratios. Characterization of the materials was done by XRD, FTIR, cation exchange capacity and specific surface area. Use of high NaOH/sediment ratio favored the formation of zeolite. The potential value of the zeolitic materials for the retention of trivalent chromium from water was examined. The maximum of Cr(III) sorption by the zeolitic materials, determined by a repeated batch equilibration method, ranged from 38.9 to 75.8 mg/g which was much greater than that of the thermally treated sediment (6.3 mg/g). No release of sorbed Cr(III) by 1.0M MgCl(2) at pH 7 was observed but Cr(III) desorption by ionic electrolyte increased with decreasing pH. The zeolitic materials could completely remove Cr(III) from wastewater even in the presence of Na(+) and Ca(2+) with high concentrations with a dose above 2.5 g/L. The pH-dependent desorption behavior and the high selectivity of zeolitic material for Cr(III) were explained by sorption at surface hydroxyl sites and formation of surface precipitates.

Cultivation of Chlorella vulgaris and Arthrospira platensis with Recovered Phosphorus from Wastewater by Means of Zeolite Sorption

PubMed Central

Markou, Giorgos; Depraetere, Orily; Vandamme, Dries; Muylaert, Koenraad

2015-01-01

In this study, zeolite was employed for the separation and recovery of P from synthetic wastewater and its use as phosphorus (P) source for the cultivation of the green microalga Chlorella vulgaris and the cyanobacterium Arthrospira (Spirulina) platensis. At P-loaded zeolite concentration of 0.15–1 g/L, in which P was limited, the two species displayed quite different behavior regarding their growth and biomass composition. C. vulgaris preferred to increase the intracellular P and did not synthesize biomass, while A. platensis synthesized biomass keeping the intracellular P as low as possible. In addition under P limitation, C. vulgaris did display some little alteration of the biomass composition, while A. platensis did it significantly, accumulating carbohydrates around 70% from about 15%–20% (control). Both species could desorb P from zeolite biologically. A. platensis could recover over 65% and C. vulgaris 25% of the P bounded onto zeolite. When P-loaded zeolite concentration increased to 5 g/L, P was adequate to support growth for both species. Especially in the case of C. vulgaris, growth was stimulated from the presence of P-loaded zeolite and produced more biomass compared to the control. PMID:25690037

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.

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.

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

Critical evaluation of post-consumption food waste composting employing thermophilic bacterial consortium.

PubMed

Awasthi, Mukesh Kumar; Selvam, Ammaiyappan; Lai, Ka Man; Wong, Jonathan W C

2017-12-01

Effect of single-function (oil degrading) and multi-functional bacterial consortium with zeolite as additive for post-consumption food waste (PCFW) composting was investigated through assessing the oil content reduction in a computer controlled 20-L composter. Three treatments of PCFWs combined with 10% zeolite were developed: Treatment-2 and Treatment-3 were inoculated with multi-functional (BC-1) and oil degrading bacterial consortium (BC-2), respectively, while T-1 was without bacterial inoculation and served as control. Results revealed that BC-2 inoculated treatment (T-3) was superior to control treatment and marginally better than T-2 in terms of oil degradation. The reduction of oil content was >97.8% in T-3 and 92.27% in T-2, while total organic matter degradation was marginally higher in T-2 (42.95%) than T-3 (41.67%). Other parameters of compost maturity including germination test indicated that T-2 was marginally better than T-3 and significantly enhanced the oily PCFW decomposition and shortened the composting period by 20days. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

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

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

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.

Material Science

NASA Image and Video Library

2003-01-12

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.

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.

Molecular models of site-isolated cobalt, rhodium, and iridium catalysts supported on zeolites: Ligand bond dissociation energies

DOE PAGES

Chen, Mingyang; Serna, Pedro; Lu, Jing; ...

2015-09-28

The chemistry of zeolite-supported site-isolated cobalt, rhodium, and iridium complexes that are essentially molecular was investigated with density functional theory (DFT) and the results compared with experimentally determined spectra characterizing rhodium and iridium species formed by the reactions of Rh(C 2H 4) 2(acac) and Ir(C 2H 4) 2(acac) (acac = acetylacetonate) with acidic zeolites such as dealuminated HY zeolite. The experimental results characterize ligand exchange reactions and catalytic reactions of adsorbed ligands, including olefin hydrogenation and dimerization. Two molecular models were used to characterize various binding sites of the metal complexes in the zeolites, and the agreement between experimental andmore » calculated infrared frequencies and metal-ligand distances determined by extended X-ray absorption fine structure spectroscopy was generally very good. The calculated structures and energies indicate a metal-support-oxygen (M(I)-O) coordination number of two for most of the supported complexes and a value of three when the ligands include the radicals C 2H 5 or H. The results characterizing various isomers of the supported metal complexes incorporating hydrocarbon ligands indicate that some carbene and carbyne ligands could form. Ligand bond dissociation energies (LDEs) are reported to explain the observed reactivity trends. The experimental observations of a stronger M-CO bond than M-(C 2H 4) bond for both Ir and Rh match the calculated LDEs, which show that the single-ligand LDEs of the mono and dual-ligand complexes for CO are similar to 12 and similar to 15 kcal/mol higher in energy (when the metal is Rh) and similar to 17 and similar to 20 kcal/mol higher (when the metal is Ir) than the single-ligand LDEs of the mono and dual ligand complexes for C 2H 4, respectively. The results provide a foundation for the prediction of the catalytic properties of numerous supported metal complexes, as summarized in detail here.« less

Levitation effect in zeolites: Quasielastic neutron scattering and molecular dynamics study of pentane isomers in zeolite NaY.

PubMed

Borah, Bhaskar J; Jobic, H; Yashonath, S

2010-04-14

We report the quasielastic neutron scattering (QENS) and molecular dynamics (MD) investigations into diffusion of pentane isomers in zeolite NaY. The molecular cross section perpendicular to the long molecular axis varies for the three isomers while the mass and the isomer-zeolite interaction remains essentially unchanged. Both QENS and MD results show that the branched isomers neopentane and isopentane have higher self-diffusivities as compared with n-pentane at 300 K in NaY zeolite. This result provides direct experimental evidence for the existence of nonmonotonic, anomalous dependence of self-diffusivity on molecular diameter known as the levitation effect. The energetic barrier at the bottleneck derived from MD simulations exists for n-pentane which lies in the linear regime while no such barrier is seen for neopentane which is located clearly in the anomalous regime. Activation energy is in the order E(a)(n-pentane)>E(a)(isopentane)>E(a)(neopentane) consistent with the predictions of the levitation effect. In the liquid phase, it is seen that D(n-pentane)>D(isopentane)>D(neopentane) and E(a)(n-pentane)

Levitation effect in zeolites: Quasielastic neutron scattering and molecular dynamics study of pentane isomers in zeolite NaY

NASA Astrophysics Data System (ADS)

Borah, Bhaskar J.; Jobic, H.; Yashonath, S.

2010-04-01

We report the quasielastic neutron scattering (QENS) and molecular dynamics (MD) investigations into diffusion of pentane isomers in zeolite NaY. The molecular cross section perpendicular to the long molecular axis varies for the three isomers while the mass and the isomer-zeolite interaction remains essentially unchanged. Both QENS and MD results show that the branched isomers neopentane and isopentane have higher self-diffusivities as compared with n-pentane at 300 K in NaY zeolite. This result provides direct experimental evidence for the existence of nonmonotonic, anomalous dependence of self-diffusivity on molecular diameter known as the levitation effect. The energetic barrier at the bottleneck derived from MD simulations exists for n-pentane which lies in the linear regime while no such barrier is seen for neopentane which is located clearly in the anomalous regime. Activation energy is in the order Ea(n-pentane)>Ea(isopentane)>Ea(neopentane) consistent with the predictions of the levitation effect. In the liquid phase, it is seen that D(n-pentane)>D(isopentane)>D(neopentane) and Ea(n-pentane)

GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties

PubMed Central

Sharma, Pankaj; Song, Ju-Sub; Han, Moon Hee; Cho, Churl-Hee

2016-01-01

GIS-NaP1 zeolite samples were synthesized using seven different Si/Al ratios (5–11) of the hydrothermal reaction mixtures having chemical composition Al2O3:xSiO2:14Na2O:840H2O to study the impact of Si/Al molar ratio on the water vapour adsorption potential, phase purity, morphology and crystal size of as-synthesized GIS-NaP1 zeolite crystals. The X-ray diffraction (XRD) observations reveal that Si/Al ratio does not affect the phase purity of GIS-NaP1 zeolite samples as high purity GIS-NaP1 zeolite crystals were obtained from all Si/Al ratios. Contrary, Si/Al ratios have remarkable effect on the morphology, crystal size and porosity of GIS-NaP1 zeolite microspheres. Transmission electron microscopy (TEM) evaluations of individual GIS-NaP1 zeolite microsphere demonstrate the characteristic changes in the packaging/arrangement, shape and size of primary nano crystallites. Textural characterisation using water vapour adsorption/desorption, and nitrogen adsorption/desorption data of as-synthesized GIS-NaP1 zeolite predicts the existence of mix-pores i.e., microporous as well as mesoporous character. High water storage capacity 1727.5 cm3 g−1 (138.9 wt.%) has been found for as-synthesized GIS-NaP1 zeolite microsphere samples during water vapour adsorption studies. Further, the total water adsorption capacity values for P6 (1299.4 mg g−1) and P7 (1388.8 mg g−1) samples reveal that these two particular samples can absorb even more water than their own weights. PMID:26964638

GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties.

PubMed

Sharma, Pankaj; Song, Ju-Sub; Han, Moon Hee; Cho, Churl-Hee

2016-03-11

GIS-NaP1 zeolite samples were synthesized using seven different Si/Al ratios (5-11) of the hydrothermal reaction mixtures having chemical composition Al2O3:xSiO2:14Na2O:840H2O to study the impact of Si/Al molar ratio on the water vapour adsorption potential, phase purity, morphology and crystal size of as-synthesized GIS-NaP1 zeolite crystals. The X-ray diffraction (XRD) observations reveal that Si/Al ratio does not affect the phase purity of GIS-NaP1 zeolite samples as high purity GIS-NaP1 zeolite crystals were obtained from all Si/Al ratios. Contrary, Si/Al ratios have remarkable effect on the morphology, crystal size and porosity of GIS-NaP1 zeolite microspheres. Transmission electron microscopy (TEM) evaluations of individual GIS-NaP1 zeolite microsphere demonstrate the characteristic changes in the packaging/arrangement, shape and size of primary nano crystallites. Textural characterisation using water vapour adsorption/desorption, and nitrogen adsorption/desorption data of as-synthesized GIS-NaP1 zeolite predicts the existence of mix-pores i.e., microporous as well as mesoporous character. High water storage capacity 1727.5 cm(3) g(-1) (138.9 wt.%) has been found for as-synthesized GIS-NaP1 zeolite microsphere samples during water vapour adsorption studies. Further, the total water adsorption capacity values for P6 (1299.4 mg g(-1)) and P7 (1388.8 mg g(-1)) samples reveal that these two particular samples can absorb even more water than their own weights.

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.

Influence of Nutrient Impregnated into Zeolite Addition on Anaerobic Digestion of Palm Oil Mill Effluent (POME)

NASA Astrophysics Data System (ADS)

Mellyanawaty, M.; Chusna, F. M. A.; Sudibyo, H.; Nurjanah, N.; Budhijanto, W.

2018-03-01

Palm oil mill effluent (POME) was wastewater generated from palm oil milling activities which was brownish liquid, acidic with pH 3-4, and contained soluble materials which were hazardous to the environment. It was characterized by high organic loading (COD 40,000–60,000 mg/L). According to its characteristics, POME was identified as a potential source to generate renewable energy through anaerobic digestion. In other words, a combination of wastewater treatment and renewable energy production would be an additional advantage to the palm oil industries. Methanogenesis was the rate limiting step in anaerobic digestion. In the conventional anaerobic digester, it required large reactors and long retention time. The addition of microbial immobilization media was to improve anaerobic reactor performance in term of higher organic removal and methane production. Additionally, better performance could lead to reduction of reactor volume and shorter retention time in high rate anaerobic digester. The loading of essential microorganism nutrient into the media might increase the affinity of bacteria to attach and grow on the media surface. Activating or inhibition effects of natural and modified zeolite addition in anaerobic digestion of POME was studied in batch reactors using erlenmeyer of 1,000 mL at COD concentrations of about 8,000 mg/L. Zeolite was impregnated with nickel and magnesium at concentrations of 0.0561 mg Ni/g zeolite and 0.0108 mg Mg/g zeolite. The effect of the different zeolite addition was determined by the measurement of soluble COD (sCOD), Volatile Fatty Acids (VFAs) and biogas production. Greater effect of modified zeolite was observed in zeolite impregnated with nickel with a 54% increase of biogas production. Meanwhile, the modified zeolite impregnated with magnesium had no positive impact to the methanogenic bacteria activities.

On the Role of Acidity in Bulk and Nanosheet [T]MFI (T=Al3+ , Ga3+, Fe3+, B3+) Zeolites in the Methanol‐to‐Hydrocarbons Reaction

PubMed Central

Meng, Lingqian; Zhu, Xiaochun; Mezari, Brahim; Pestman, Robert; Wannapakdee, Wannaruedee

2017-01-01

Abstract The influence of framework substituents (Al3+, Ga3+, Fe3+ and B3+) and morphology (bulk vs. nanometer‐sized sheets) of MFI zeolites on the acidity and catalytic performance in the methanol‐to‐hydrocarbons (MTH) reaction was investigated. The Brønsted acid density and strength decreased in the order Al(OH)Si>Ga(OH)Si>Fe(OH)Si≫B(OH)Si. Pyridine 15N NMR spectra confirmed the differences in the Brønsted and Lewis acid strengths but also provided evidence for site heterogeneity in the Brønsted acid sites. Owing to the lower efficiency with which tervalent ions can be inserted into the zeolite framework, sheet‐like zeolites exhibited lower acidity than bulk zeolites. The sheet‐like Al‐containing MFI zeolite exhibited the greatest longevity as a MTH catalyst, outperforming its bulk [Al]MFI counterpart. Although the lower acidity of bulk [Ga]MFI led to a better catalytic performance than bulk [Al]MFI, the sheet‐like [Ga]MFI sample was found to be nearly inactive owing to lower and heterogeneous Brønsted acidity. All Fe‐ and B‐substituted zeolite samples displayed very low catalytic performance owing to their weak acidity. Based on the product distribution, the MTH reaction was found to be dominated by the olefins‐based catalytic cycle. The small contribution of the aromatics‐based catalytic cycle was larger for bulk zeolite than for sheet‐like zeolite, indicating that shorter residence time of aromatics can explain the lower tendency toward coking and enhanced catalyst longevity. PMID:29201243

Seonah Kim, Ph.D. | NREL

Science.gov Websites

lignocellulosic biomass enzymes Design of new catalysts for vapor phase upgrading of biomass pyrolysis Enzymatic Engineering for Continuous Hydrocarbon Fuel Production (PI) Computational Pyrolysis Consortium Zeolite design Celluase enzyme structure-function relationships to design enhanced cellulose systems Catalyst

DEVELOPMENT OF NONCARBON SORBENTS FOR HG0 REMOVAL FROM COAL-FIRED POWER PLANTS

EPA Science Inventory

Noncarbon materials or mineral oxides (silica gel, alumina, molecular sieves, zeolites, and montmorillonite) were modified with various functional groups, such as amine, amide, thiol, and urea; and active additives, such as elemental sulfur, sodium sulfide, and sodium polysulfide...

COMBINED SORBENT/CATALYST MEDIA FOR DESTRUCTION OF HALOGENATED VOCS

EPA Science Inventory

Several chromium modified zeolites have been developed and tested for their ability to physisorb chlorinated VOCs (CVOCs) at ambient and then catalytically destroy them at elevated temperatures (ca. 300 degrees C). These dual function materials, which act as both sorbents and cat...

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).

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.

[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.

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.

Catalytic Oxidation of Methane into Methanol over Copper-Exchanged Zeolites with Oxygen at Low Temperature

PubMed Central

2016-01-01

The direct catalytic conversion of methane to liquid oxygenated compounds, such as methanol or dimethyl ether, at low temperature using molecular oxygen is a grand challenge in C–H activation that has never been met with synthetic, heterogeneous catalysts. We report the first demonstration of direct, catalytic oxidation of methane into methanol with molecular oxygen over copper-exchanged zeolites at low reaction temperatures (483–498 K). Reaction kinetics studies show sustained catalytic activity and high selectivity for a variety of commercially available zeolite topologies under mild conditions (e.g., 483 K and atmospheric pressure). Transient and steady state measurements with isotopically labeled molecules confirm catalytic turnover. The catalytic rates and apparent activation energies are affected by the zeolite topology, with caged-based zeolites (e.g., Cu-SSZ-13) showing the highest rates. Although the reaction rates are low, the discovery of catalytic sites in copper-exchanged zeolites will accelerate the development of strategies to directly oxidize methane into methanol under mild conditions. PMID:27413787

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.

In situ solid-state NMR and XRD studies of the ADOR process and the unusual structure of zeolite IPC-6

NASA Astrophysics Data System (ADS)

Morris, Samuel A.; Bignami, Giulia P. M.; Tian, Yuyang; Navarro, Marta; Firth, Daniel S.; Čejka, Jiří; Wheatley, Paul S.; Dawson, Daniel M.; Slawinski, Wojciech A.; Wragg, David S.; Morris, Russell E.; Ashbrook, Sharon E.

2017-10-01

The assembly-disassembly-organization-reassembly (ADOR) mechanism is a recent method for preparing inorganic framework materials and, in particular, zeolites. This flexible approach has enabled the synthesis of isoreticular families of zeolites with unprecedented continuous control over porosity, and the design and preparation of materials that would have been difficult—or even impossible—to obtain using traditional hydrothermal techniques. Applying the ADOR process to a parent zeolite with the UTL framework topology, for example, has led to six previously unknown zeolites (named IPC-n, where n = 2, 4, 6, 7, 9 and 10). To realize the full potential of the ADOR method, however, a further understanding of the complex mechanism at play is needed. Here, we probe the disassembly, organization and reassembly steps of the ADOR process through a combination of in situ solid-state NMR spectroscopy and powder X-ray diffraction experiments. We further use the insight gained to explain the formation of the unusual structure of zeolite IPC-6.

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.

Highly Oriented Growth of Catalytically Active Zeolite ZSM-5 Films with a Broad Range of Si/Al Ratios.

PubMed

Fu, Donglong; Schmidt, Joel E; Ristanović, Zoran; Chowdhury, Abhishek Dutta; Meirer, Florian; Weckhuysen, Bert M

2017-09-04

Highly b-oriented zeolite ZSM-5 films are critical for applications in catalysis and separations and may serve as models to study diffusion and catalytic properties in single zeolite channels. However, the introduction of catalytically active Al 3+ usually disrupts the orientation of zeolite films. Herein, using structure-directing agents with hydroxy groups, we demonstrate a new method to prepare highly b-oriented zeolite ZSM-5 films with a broad range of Si/Al ratios (Si/Al=45 to ∞). Fluorescence micro-(spectro)scopy was used to monitor misoriented microstructures, which are invisible to X-ray diffraction, and show Al 3+ framework incorporation and illustrate the differences between misoriented and b-oriented films. The methanol-to-hydrocarbons process was studied by operando UV/Vis diffuse reflectance micro-spectroscopy with on-line mass spectrometry, showing that the b-oriented zeolite ZSM-5 films are active and stable under realistic process conditions. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Highly Oriented Growth of Catalytically Active Zeolite ZSM‐5 Films with a Broad Range of Si/Al Ratios

PubMed Central

Fu, Donglong; Schmidt, Joel E.; Ristanović, Zoran; Chowdhury, Abhishek Dutta; Meirer, Florian

2017-01-01

Abstract Highly b‐oriented zeolite ZSM‐5 films are critical for applications in catalysis and separations and may serve as models to study diffusion and catalytic properties in single zeolite channels. However, the introduction of catalytically active Al3+ usually disrupts the orientation of zeolite films. Herein, using structure‐directing agents with hydroxy groups, we demonstrate a new method to prepare highly b‐oriented zeolite ZSM‐5 films with a broad range of Si/Al ratios (Si/Al=45 to ∞). Fluorescence micro‐(spectro)scopy was used to monitor misoriented microstructures, which are invisible to X‐ray diffraction, and show Al3+ framework incorporation and illustrate the differences between misoriented and b‐oriented films. The methanol‐to‐hydrocarbons process was studied by operando UV/Vis diffuse reflectance micro‐spectroscopy with on‐line mass spectrometry, showing that the b‐oriented zeolite ZSM‐5 films are active and stable under realistic process conditions. PMID:28675590

Solid-support substrates for plant growth at a lunar base

NASA Technical Reports Server (NTRS)

Ming, D. W.; Galindo, C.; Henninger, D. L.

1990-01-01

Zeoponics is only in its developmental stages at the Johnson Space Center and is defined as the cultivation of plants in zeolite substrates that contain several essential plant growth cations on their exchange sites, and have minor amounts of mineral phases and/or anion-exchange resins that supply essential plant growth anions. Zeolites are hydrated aluminosilicates of alkali and alkaline earth cations with the ability to exchange most of their constituent exchange cations as well as hydrate/dehydrate without change to their structural framework. Because zeolites have extremely high cation exchange capabilities, they are very attractive media for plant growth. It is possible to partially or fully saturate plant-essential cations on zeolites. Zeoponic systems will probably have their greatest applications at planetary bases (e.g., lunar bases). Lunar raw materials will have to be located that are suited for the synthesis of zeolites and other exchange resings. Lunar 'soil' simulants have been or are being prepared for zeolite/smectite synthesis and 'soil' dissolution studies.

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.

Studying Two-Dimensional Zeolites with the Tools of Surface Science: MFI Nanosheets on Au(111)

DOE PAGES

J. D. Kestell; Zhong, J. Q.; Shete, M.; ...

2016-07-26

While surface science has provided fundamental insights into a variety a materials, the most used catalysts in the industry, namely zeolites, still remain a challenge. The recent preparation of two-dimensional versions of MFI zeolite frameworks and the possibility of their deposition on electrically conductive supports provides for the first time a viable strategy to perform detailed studies on industrially relevant zeolites using the vast toolkit of surface science. In this work we demonstrate the use of infrared reflection absorption spectroscopy (IRRAS) and synchrotron-based x-ray photoelectron spectroscopy (XPS) to study these materials. Furthermore, polarization modulation IRRAS is used to study themore » adsorption of methanol and its effect in phonon vibrations of the zeolite framework. The possibility of using surface science methods, in particular under ambient pressure conditions, for the study of well-defined zeolites and other microporous structures opens new avenues to understand structural and mechanistic aspects of these materials as catalysts, adsorbents and molecular sieves.« less

Studying Two-Dimensional Zeolites with the Tools of Surface Science: MFI Nanosheets on Au(111)

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

J. D. Kestell; Zhong, J. Q.; Shete, M.

While surface science has provided fundamental insights into a variety a materials, the most used catalysts in the industry, namely zeolites, still remain a challenge. The recent preparation of two-dimensional versions of MFI zeolite frameworks and the possibility of their deposition on electrically conductive supports provides for the first time a viable strategy to perform detailed studies on industrially relevant zeolites using the vast toolkit of surface science. In this work we demonstrate the use of infrared reflection absorption spectroscopy (IRRAS) and synchrotron-based x-ray photoelectron spectroscopy (XPS) to study these materials. Furthermore, polarization modulation IRRAS is used to study themore » adsorption of methanol and its effect in phonon vibrations of the zeolite framework. The possibility of using surface science methods, in particular under ambient pressure conditions, for the study of well-defined zeolites and other microporous structures opens new avenues to understand structural and mechanistic aspects of these materials as catalysts, adsorbents and molecular sieves.« less

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 more favorably, which ultimately decreased the CH3Cl selectivity. Such trade-off relationship between CH4 conversion and CH3Cl selectivity can be slightly broken by using Pt/NaY zeolite catalyst that is known to possess Frustrated Lewis Pairs (FLP) that are very useful for ionic cleavage of H2 to H+ and H-. Similarly, in the present work, Pt/NaY(FLP) catalysts enhanced the CH4 conversion while keeping the CH3Cl selectivity as compared to the Pt/HY zeolite catalysts.