X-ray and FIB Tomography of Extremely High Surface Area Nanostructured Hollow Fiber Membranes

2012 ◽  
Vol 1421 ◽  
Author(s):  
Amy J. Grano ◽  
Franchessa M. Sayler ◽  
Amber Genau ◽  
Keana L. Graves ◽  
Brian M. Patterson ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Porous Silica ◽  
Porous Metal ◽  
Sample Volume ◽  
Ionic Conductors ◽  
Hierarchically Porous ◽  
X Ray ◽  
Synthesis Conditions ◽  
Wide Range

ABSTRACTHierarchically porous materials are of interest in a wide range of applications. If the materials are electronic, or ionic conductors, such materials are of interest as electrodes for use in fuel cells. Using hierarchically porous silica as templates, we have demonstrated the formation of hierarchically porous metal and metal oxide structures. Through the control of the synthesis conditions, we have produced partial replicas ca. 1 cubic centimeter in volume, in which two macroporous networks are separated by a nanoporous membrane. The macroporous network in the silica template is known to be bicontinuous. Our underlying model predicts that the second, induced, macroporous network should be similarly bicontinuous.Micrometer resolution X-ray tomography of the whole sample confirms that the synthesis produces one bicontinuous macroporous network, and is consistent with the existence of a second set of macropores. Preliminary experiments were carried out using FIB/SEM serial tomography to image the second macropore network, however, the length scale of the structures is such that this approach it is unable to firmly establish that the second macropore network is bicontinuous throughout the entire sample volume.

scholarly journals Fractal Structure in Silica and Composites Aerogels

Gels ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Thierry Woignier ◽  
Juan Primera ◽  
Adil Alaoui ◽  
Philippe Dieudonne ◽  
Laurent Duffours ◽  
...  
Keyword(s):  
Fractal Structure ◽  
High Surface ◽  
High Surface Area ◽  
Silica Aerogels ◽  
High Porosity ◽  
Material Density ◽  
X Ray ◽  
Synthesis Conditions ◽  
Fractal Characteristics ◽  
Synthesis Procedure

Silica aerogels are known to be materials with exceptional characteristics, such as ultra-low density, high surface area, high porosity, high adsorption, and low-thermal conductivity. In addition, these unique properties are mainly related to their specific processing. Depending on the aerogel synthesis procedure, the aerogels texture can be tailored with meso and/or macroporosity. Fractal geometry has been observed and used to describe silica aerogels at nanoscales in certain conditions. In this review paper, we describe the fractal structure of silica aerogels that can develop depending on the synthesis conditions. X-ray and neutron scattering measurements allow to show that silica aerogels can exhibit a fractal structure over one or even more than two orders of magnitude in length. The fractal dimension does not depend directly on the material density but can vary with the synthesis conditions. It ranges typically between 1.6 and 2.4. The effect of the introduction of silica particles or of further thermal treatment or compression of the silica aerogels on their microstructure and their fractal characteristics is also resumed.

scholarly journals Enhanced Potential Toxic Metal Removal Using a Novel Hierarchical SiO2–Mg(OH)2 Nanocomposite Derived from Sepiolite

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 298 ◽  
Author(s):  
Qi-Zhi Yao ◽  
Sheng-Hui Yu ◽  
Tian-Lei Zhao ◽  
Fei-Jin Qian ◽  
Han Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heavy Metals ◽  
Metal Removal ◽  
Structural Characteristics ◽  
High Surface ◽  
High Surface Area ◽  
Raw Material ◽  
Amorphous Sio2 ◽  
X Ray ◽  
Wide Range

Clays are widely used as sorbents for heavy metals due to their high specific surface areas, low cost, and ubiquitous occurrence in most soil and sediment environments. However, the low loading capacity for heavy metals is one of their inherent limitations. In this work, a novel SiO2–Mg(OH)2 nanocomposite was successfully prepared via sequential acid–base modification of raw sepiolite. The structural characteristics of the resulting modified samples were characterized by a wide range of techniques including field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and nitrogen physisorption analysis. The results show that a hierarchical nanocomposite constructed by loading the Mg(OH)2 nanosheets onto amorphous SiO2 nanotubes can be successfully prepared, and the nanocomposite has a high surface area (377.3 m2/g) and pore volume (0.96 cm3/g). Batch removal experiments indicate that the nanocomposite exhibits high removal efficiency toward Gd(III), Pb(II), and Cd(II), and their removal capacities were greatly enhanced in comparison with raw sepiolite, due to the synergistic effect of the different components in the hierarchical nanocomposite. This work can provide a novel route toward a hierarchical nanocomposite by using clay minerals as raw material. Taking into account the simplicity of the fabrication route and the high loading capacities for heavy metals, the developed nanocomposite also has great potential applications in water treatment.

Application of 3-D Hierarchically Porous Silver, Cobalt Oxide and Zinc Oxide Monoliths to Chromatographic Separations

2012 ◽  
Vol 1389 ◽  
Author(s):  
Franchessa M. Sayler ◽  
Amy Grano ◽  
Susan Wiedmer ◽  
Jan-Henrik Smått ◽  
Martin G. Bakker
Keyword(s):  
Zinc Oxide ◽  
Cobalt Oxide ◽  
High Surface ◽  
High Surface Area ◽  
Porous Silica ◽  
Chromatographic Separations ◽  
Hierarchically Porous ◽  
Molecular Separation ◽  
Porous Silver ◽  
Liquid Chromatographic

ABSTRACTHierarchically porous silica monoliths were introduced into liquid phase chromatography at the beginning of the last decade. The high surface area, high void volume and bicontinuous nature of the porosity of the materials are significant advantages over existing chromatographic supports and have resulted in rapid acceptance of these materials into the chromatography market.We report here on the synthesis of 3-D porous silver, cobalt oxide and zinc oxide monoliths, their materials characterization, fabrication as liquid chromatographic columns and initial chromatographic characterization. The, as prepared, columns gave very low back pressure, consistent with the bicontinuous nature of the columns. Cobalt oxide and zinc oxide both demonstrated retention of a number of nitrogen heterocycles, providing the basis for molecular separation.

Formation and Applications of Hierarchically Porous Carbon, Metals and Metal Oxides Formed by Nanocasting

2012 ◽  
Vol 1389 ◽  
Author(s):  
Franchessa M. Sayler ◽  
Amy J. Grano ◽  
William Scogin ◽  
Pasha Sanders ◽  
Jan-Henrik Smått ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Porous Carbon ◽  
Porous Silica ◽  
Ionic Conductors ◽  
Hierarchically Porous ◽  
Surface Areas ◽  
Wide Range ◽  
Hierarchically Porous Materials ◽  
Silica Template

ABSTRACTHierarchically porous materials are of interest in a wide range of applications. If the materials are electronic or ionic conductors such materials are of interest as electrodes for use in fuel cells, flow batteries, electrocatalysis, and pseudo/supercapacitors. We have demonstrated the synthesis of hierarchically porous carbon, metal and metal oxide monoliths. Hierarchically porous silica with porosity at three length scales: 0.5-30 micrometer, 200-500 nm, and 3-8 nm, is used as a template to form these materials. The porosity of the silica template is produced by spinodal decomposition (0.5-30 micrometer), particle agglomeration (200-500 nm) and addition of surfactant or block copolymer (3-8 nm). Nanocasting: replication of all or part of the structure via one of a number of chemical replication techniques has been used to produce the carbon, metal oxide and metal replicas. The final surface areas of the materials can be as high as 1200 m2/g for carbon replicas, and >300 m2/g for metals and metal oxides. The use of the nanocasting technique allows for formation of materials that are compositionally or spatially heterogeneous.We report here results on the synthesis and characterization of hierarchically porous monoliths of carbon and, nickel and the use of some of these monoliths in catalysis and electrochemical capacitors.

scholarly journals Understanding Pore Surface Modification of Sucrose-Modified Iron Oxide/Silica Mesoporous Composite for Degradation of Methylene Blue

2021 ◽  
Vol 16 (3) ◽  
pp. 459-471
Author(s):  
Yuvita Eka Pertiwi ◽  
Maria Ulfa ◽  
Teguh Endah Saraswati ◽  
Didik Prasetyoko ◽  
Wega Trisunaryanti
Keyword(s):  
Methylene Blue ◽  
Iron Oxide ◽  
Surface Area ◽  
Heterogeneous Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Impregnation Method ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Wide Range

Santa Barbara Amorphous (SBA-15) containing iron oxide with a sucrose-modified in a heterogeneous reaction for degradation methylene blue (MB) successful synthesized used hydrothermal, ultrasonication, and wet impregnation method. SBA-15 is mesoporous silica that can easily serve as external and internal surfaces making it suitable for a wide range of applications. The structure and morphology of materials were characterized using Surface Area Analyzer (SAA), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), and Transmission Electron Microscopy (TEM). Iron oxide impregnated as a maghemite phase has an average size of 12 nm and well distributed on the SBA-15. After modified with sucrose the materials remaining stable, which has a two-dimensional hexagonal (p6mm) structure, high specific surface area, and large pore volume (up to 1.82 cm3.g−1). The degradation of MB was evaluated under visible light irradiation using UV-Vis spectroscopy. Catalytic activity showed efficiencies of 52.9; 70.2; and 21.1% for SBA-15, Fe2O3/SBA-15, and sucrose-modified Fe2O3/SBA-15 respectively. Sucrose-modified Fe2O3/SBA-15 has the lowest efficiency, which probably occurs due to the presence of pore-blocking and the formation of micropores on the external pore. The modification with sucrose has the advantage of producing a high surface area even though there is a catalytic center due to partial decomposition which causes a decrease in the efficiency of degradation of MB. All materials provide a high micro surface area so that they can be further adapted and can be widely applied to many potential applications as both catalyst support and an adsorbent. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

scholarly journals Synthesis, characterization, and reactivity of tungsten oxynitride

1998 ◽  
Vol 13 (8) ◽  
pp. 2321-2327 ◽  
Author(s):  
Toby E. Lucy ◽  
Todd P. St. Clair ◽  
S. Ted Oyama
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
X Ray Diffraction ◽  
Heating Rates ◽  
Continuous Transformation ◽  
X Ray ◽  
Synthesis Conditions ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction

High surface area tungsten oxynitride has been prepared by the temperature programmed reaction (TPR) of WO3 with NH3. All samples were characterized by x-ray diffraction (XRD), nitrogen physisorption, CO chemisorption, and elemental analysis. Samples were prepared at different heating rates (β), and a Redhead analysis yielded an activation energy for nitridation of 109 kJ mol−1. A heating rate of 0.016 K s−1 gave optimal synthesis conditions. Solid state intermediates were studied by interrupting the temperature program at various stages. No distinct suboxide phases were found using XRD. The nitridation step was determined to be a continuous transformation from oxide to oxynitride. Surface area, CO uptake, and nitrogen weight % were all found to increase as the reaction progressed. Reactivity experiments showed reasonable hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) activity, but little hydrogenation (HYD) or hydrodesulfurization (HDS) activity.

scholarly journals Non-Thermal Plasma-Modified Ru-Sn-Ti Catalyst for Chlorinated Volatile Organic Compound Degradation

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1456
Author(s):  
Yujie Fu ◽  
You Zhang ◽  
Qi Xin ◽  
Zhong Zheng ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Surface Oxidation ◽  
Treatment Method ◽  
X Ray ◽  
Chlorinated Volatile Organic Compounds ◽  
Volatile Organic ◽  
Doped Titania

Chlorinated volatile organic compounds (CVOCs) are vital environmental concerns due to their low biodegradability and long-term persistence. Catalytic combustion technology is one of the more commonly used technologies for the treatment of CVOCs. Catalysts with high low-temperature activity, superior selectivity of non-toxic products, and resistance to chlorine poisoning are desirable. Here we adopted a plasma treatment method to synthesize a tin-doped titania loaded with ruthenium dioxide (RuO2) catalyst, possessing enhanced activity (T90%, the temperature at which 90% of dichloromethane (DCM) is decomposed, is 262 °C) compared to the catalyst prepared by the conventional calcination method. As revealed by transmission electron microscopy, X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction, the high surface area of the tin-doped titania catalyst and the enhanced dispersion and surface oxidation of RuO2 induced by plasma treatment were found to be the main factors determining excellent catalytic activities.

scholarly journals A Brief Overview of Recent Progress in Porous Silica as Catalyst Supports

2021 ◽  
Vol 5 (3) ◽  
pp. 75
Author(s):  
Preeti S. Shinde ◽  
Pradnya S. Suryawanshi ◽  
Kanchan K. Patil ◽  
Vedika M. Belekar ◽  
Sandeep A. Sankpal ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
High Surface ◽  
High Surface Area ◽  
Porous Silica ◽  
Textural Properties ◽  
Silica Particles ◽  
Catalyst Supports ◽  
Silica Supports ◽  
Low Degree ◽  
Transfer Properties

Porous silica particles have shown applications in various technological fields including their use as catalyst supports in heterogeneous catalysis. The mesoporous silica particles have ordered porosity, high surface area, and good chemical stability. These interesting structural or textural properties make porous silica an attractive material for use as catalyst supports in various heterogeneous catalysis reactions. The colloidal nature of the porous silica particles is highly useful in catalytic applications as it guarantees better mass transfer properties and uniform distribution of the various metal or metal oxide nanocatalysts in solution. The catalysts show high activity, low degree of metal leaching, and ease in recycling when supported or immobilized on porous silica-based materials. In this overview, we have pointed out the importance of porous silica as catalyst supports. A variety of chemical reactions catalyzed by different catalysts loaded or embedded in porous silica supports are studied. The latest reports from the literature about the use of porous silica-based materials as catalyst supports are listed and analyzed. The new and continued trends are discussed with examples.

scholarly journals Attached β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane to graphene oxide and its application in copper removal

2017 ◽  
Vol 75 (10) ◽  
pp. 2403-2411 ◽  
Author(s):  
Zongxue Yu ◽  
Qi Chen ◽  
Liang Lv ◽  
Yang Pan ◽  
Guangyong Zeng ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
High Surface ◽  
High Surface Area ◽  
Esterification Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cavity Structure ◽  
Optimum Ph ◽  
Exchange Adsorption ◽  
Langmuir Isotherm Model

The environmental applications of graphene oxide and β-cyclodextrin (β-CD) have attracted great attention since their first discovery. Novel nanocomposites were successfully prepared by using an esterification reaction between β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane grafted graphene oxide (β-CD/GPTMS/GO). The β-CD/GPTMS/GO nanocomposites were used to remove the Cu2+ from aqueous solutions. The characteristics of β-CD/GPTMS/GO were detected by scanning electron microscopy (SEM), Fourier transform infrared, X-ray diffraction (XRD), thermogravimetric analysis (TG) and energy dispersive X-ray (EDX). The dispersibility of graphene oxide was excellent due to the addition of β-CD. The adsorption isotherms data obtained at the optimum pH 7 were fitted by Langmuir isotherm model. The excellent adsorption properties of β-CD/GPTMS/GO for Cu2+ ions could be attributed to the apolar cavity structure of β-CD, the high surface area and abundant functional groups on the surface of GO. The adsorption patterns of β-CD/GPTMS/GO were electrostatic attraction, formation of host-guest inclusion complexes and the ion exchange adsorption. The efficient adsorption of β-CD/GPTMS/GO for Cu2+ ions suggested that these novel nanocomposites may be ideal candidates for removing other cation pollutants from waste water.

Facile Synthesis of Unique Bismuth Vanadate Nano-Knitted Hollow Cage and its Application in Environmental Remediation

2019 ◽  
Vol 74 (3) ◽  
pp. 259-263 ◽  
Author(s):  
M. Shamshi Hassan
Keyword(s):  
Environmental Remediation ◽  
Dye Degradation ◽  
High Surface ◽  
High Surface Area ◽  
Bismuth Vanadate ◽  
Bandgap Energy ◽  
Blue Dye ◽  
X Ray ◽  
Photodegradation Efficiency ◽  
Hollow Nanostructure

AbstractHierarchical bismuth vanadate (BiVO4) nano-knitted hollow cages have been synthesized by simple hydrothermal method and characterized by scanning electron microscopy, x-ray diffraction, energy-dispersive x-ray spectrometer, Fourier transform infrared, UV-Vis, and Raman. The photodegradation efficiency of BiVO4 nanocage for universally used methylene blue dye. The BiVO4 hollow nanostructure demonstrated better photocatalytic competence in dye degradation as compared to the commercial TiO2 powders (P25). The excellent dye degradation can be certified to the high crystallisation of monoclinic BiVO4 and hollow nanostructure, which leads to high surface area and small bandgap energy of 2.44 eV.

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