Preparation and Properties of Clays Pillared with Al2O3-NiO Mixed Oxide

1994 ◽  
Vol 371 ◽  
Author(s):  
Shoji Yamanaka ◽  
Hironori Yamamoto
Keyword(s):  
Ion Exchange ◽  
Specific Surface ◽  
Surface Area ◽  
Aluminum Hydroxide ◽  
Mixed Oxide ◽  
Nickel Hydroxide ◽  
Room Temperature ◽  
Microporous Structure ◽  
Titration Method ◽  
Na Ions

AbstractMontmorillonite was pillared with Al2O3-NiO mixed oxide by ion-exchange combined with titration process; the interlayer Na ions of montmorillonite were first exchanged with aluminum hydroxide polycations, and then nickel hydroxide was precipitated between the layers by a titration method. The aluminum hydroxide pillars reacted with the nickel hydroxide at room temperature, and the microporous structure was much stabilized against heating. The specific surface area as high as 300 m2/g was maintained up to 700°C.

The Reactivity of Different Active Forms of Sodium Carbonate with Respect to Sulfur Dioxide

1992 ◽  
Vol 57 (11) ◽  
pp. 2302-2308
Author(s):  
Karel Mocek ◽  
Erich Lippert ◽  
Emerich Erdös
Keyword(s):  
Thermal Decomposition ◽  
Liquid Phase ◽  
Sulfur Dioxide ◽  
Specific Surface ◽  
Surface Area ◽  
Sodium Carbonate ◽  
Room Temperature ◽  
Active Form ◽  
The Other ◽  
Kinetics Of

The kinetics of the reaction of solid sodium carbonate with sulfur dioxide depends on the microstructure of the solid, which in turn is affected by the way and conditions of its preparation. The active form, analogous to that obtained by thermal decomposition of NaHCO3, emerges from the dehydration of Na2CO3 . 10 H2O in a vacuum or its weathering in air at room temperature. The two active forms are porous and have approximately the same specific surface area. Partial hydration of the active Na2CO3 in air at room temperature followed by thermal dehydration does not bring about a significant decrease in reactivity. On the other hand, if the preparation of anhydrous Na2CO3 involves, partly or completely, the liquid phase, the reactivity of the product is substantially lower.

Application of ion-exchange materials with high specific surface area for solving environmental problems

2014 ◽  
Vol 84 (13) ◽  
pp. 2545-2551
Author(s):  
M. K. Rustamov ◽  
D. A. Gafurova ◽  
M. M. Karimov ◽  
N. M. Rustamova ◽  
D. Zh. Bekchonov ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Environmental Problems ◽  
High Specific Surface Area

scholarly journals The Properties of Screen Printed (Bi,Pb)-Sr-Ca-Cu-O Thick Films Based On Decomposed Oxalate Powders

1993 ◽  
Vol 15 (3-4) ◽  
pp. 155-163
Author(s):  
J. Hagberg
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mixed Oxide ◽  
Thick Films ◽  
Average Particle Size ◽  
Nominal Composition ◽  
Average Particle ◽  
Transmission Electron ◽  
Screen Printed

The significance of powder and paste characteristics was studied in order to improve the morphology and structure of superconducting (Bi,Pb)-Sr-Ca-Cu-O screen printed thick films. Powder with nominal composition of Bi1.75Pb0.4Sr1.9Ca2.1Cu3.2Oywas prepared via the oxalate route and decomposed at 430 to 795℃. The decomposed powders were characterized by X-ray diffraction, transmission electron microscopy and specific surface area measurements. These studies showed a variation of specific surface area from 16.5 to 0.9 m2/g and a variation of the average particle size from 100 nm to 800 nm in the studied temperature interval. The phase structure showed three distinct temperature areas; between 430 to 620, 620 to 715, and at 795℃.Thick-film pastes were made by the addition of an organic vehicle at 500, 620, 650 and 795℃ to decompose annealed oxalate synthesized powders and, for comparison, the vehicle was also added to sintered mixed-oxide/carbonate-based powder in weight ratios from 0.42 to 0.54:1. Films were screen printed on single crystal MgO (100) substrates and melt annealed at 890 to 895℃ for 3 min and subsequently, for prolonged diffusion, annealed at 852℃. After firing, the films were mainly composed of the (001) textured (Bi,Pb)2Sr2Ca2Cu3Oyphase. The reference films, made from mixed oxide/carbonate powder, resembled the films based on oxalate powders decomposed at 795℃. Films based on oxalate powders, decomposed at lower temperatures, were smoother and were able to carry noticeably higher currents than films based on powders decomposed at higher temperatures.

scholarly journals Preparation and Application of 2D MXene-Based Gas Sensors: A Review

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 225
Author(s):  
Qingting Li ◽  
Yanqiong Li ◽  
Wen Zeng
Keyword(s):  
Composite Materials ◽  
Specific Surface ◽  
Surface Area ◽  
Gas Sensor ◽  
Specific Surface Area ◽  
Gas Sensors ◽  
Room Temperature ◽  
Gas Sensing ◽  
Interlayer Spacing ◽  
Preparation Methods

Since MXene (a two-dimensional material) was discovered in 2011, it has been favored in all aspects due to its rich surface functional groups, large specific surface area, high conductivity, large porosity, rich organic bonds, and high hydrophilicity. In this paper, the preparation of MXene is introduced first. HF etching was the first etching method for MXene; however, HF is corrosive, resulting in the development of the in situ HF method (fluoride + HCl). Due to the harmful effects of fluorine terminal on the performance of MXene, a fluorine-free preparation method was developed. The increase in interlayer spacing brought about by adding an intercalator can affect MXene’s performance. The usual preparation methods render MXene inevitably agglomerate and the resulting yields are insufficient. Many new preparation methods were researched in order to solve the problems of agglomeration and yield. Secondly, the application of MXene-based materials in gas sensors was discussed. MXene is often regarded as a flexible gas sensor, and the detection of ppb-level acetone at room temperature was observed for the first time. After the formation of composite materials, the increasing interlayer spacing and the specific surface area increased the number of active sites of gas adsorption and the gas sensitivity performance improved. Moreover, this paper discusses the gas-sensing mechanism of MXene. The gas-sensing mechanism of metallic MXene is affected by the expansion of the lamellae and will be doped with H2O and oxygen during the etching process in order to become a p-type semiconductor. A p-n heterojunction and a Schottky barrier forms due to combinations with other semiconductors; thus, the gas sensitivities of composite materials are regulated and controlled by them. Although there are only several reports on the application of MXene materials to gas sensors, MXene and its composite materials are expected to become materials that can effectively detect gases at room temperature, especially for the detection of NH3 and VOC gas. Finally, the challenges and opportunities of MXene as a gas sensor are discussed.

Preparation and characterization of porous cordierite for potential use in cellular ceramics

2009 ◽  
Vol 63 (4) ◽  
Author(s):  
Marta Valášková ◽  
Gražyna Martynková
Keyword(s):  
Specific Surface ◽  
Size Distribution ◽  
Surface Area ◽  
Aluminum Hydroxide ◽  
Specific Surface Area ◽  
Porous Ceramics ◽  
High Porosity ◽  
Cordierite Ceramics ◽  
Potential Use

AbstractCordierite porous ceramics Z, X, and K were prepared using three mixtures of clay minerals: Z from kaolinite, talc, and aluminum hydroxide, X from kaolinite, talc, vermiculite, and aluminum hydroxide, and K from kaolinite, talc, and magnesium oxide. Ceramics were different in porosity, specific surface area, cordierite polymorphs, and secondary crystalline phases. Vermiculite influenced textural architecture of calcined cordierite ceramics X and predestinated crystallization of the high-temperature hexagonal α-cordierite with secondary minerals enstatite, spinel and corundum. Ceramics Z contained low-temperature orthorhombic β-cordierite, enstatite, and corundum, K was diphase of β-cordierite and forsterite. Total pore area (TPA) and specific surface area (SSA) of X, in spite of the higher porosity and the pore size distribution in the range of 300–1000 nm, were smaller in comparison with TPA and SSA of Z. Ceramics K retained high porosity, two maxima at 300–1000 nm and 50–200 nm in the pores size distribution, and the highest TPA and SSA compared to those observed in ceramics Z and X.

Cerium–zirconium mixed oxide synthesized by sol-gel method and its effect on the oxygen vacancy and specific surface area

2021 ◽  
pp. 122752
Author(s):  
Pablo Teles Aragão Campos ◽  
Claudinei Fabiano Oliveira ◽  
João Pedro Vieira Lima ◽  
Daniele Renata de Queiroz Silva ◽  
Sílvia Cláudia Loureiro Dias ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mixed Oxide ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method

scholarly journals Nano-Sized Fe(III) Oxide Particles Starting from an Innovative and Eco-Friendly Synthesis Method

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 323 ◽  
Author(s):  
Ludovico Macera ◽  
Giuliana Taglieri ◽  
Valeria Daniele ◽  
Maurizio Passacantando ◽  
Franco D’Orazio
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Ambient Pressure ◽  
Synthesis Method ◽  
Hematite Nanoparticles ◽  
X Ray

This paper introduces an original, eco-friendly and scalable method to synthesize ferrihydrite nanoparticles in aqueous suspensions, which can also be used as a precursor to produce α-hematite nanoparticles. The method, never used before to synthesize iron oxides, is based on an ion exchange process allowing to operate in one-step, with reduced times, at room temperature and ambient pressure, and using cheap or renewable reagents. The influence of reagent concentrations and time of the process on the ferrihydrite features is considered. The transformation to hematite is then analyzed and discussed in relation to different procedures: (1) A natural aging in the water at room temperature; and (2) heat treatments at different temperatures and times. Structural and morphological features of the obtained nanoparticles are investigated by means of several techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, thermal analysis, nitrogen adsorption and magnetic measurements. Ferrihydrite shows the typical spherical morphology and a very high specific surface area of 420 m2/g. Rhombohedral or plate-like hexagonal hematite nanoparticles are obtained by the two procedures, characterized by dimensions of 50 nm and 30 nm, respectively, and a specific surface area up to 57 m2/g, which is among the highest values reported in the literature for hematite NPs.

Synthesis of high surface area mixed metal oxide from the NiMgAl LDH precursor for nitro-aldol condensation reaction

2015 ◽  
Vol 39 (1) ◽  
pp. 172-178 ◽  
Author(s):  
Dipshikha Bharali ◽  
Rasna Devi ◽  
Pankaj Bharali ◽  
Ramesh C. Deka
Keyword(s):  
Metal Oxide ◽  
Surface Area ◽  
Mixed Oxide ◽  
Room Temperature ◽  
Aldol Condensation ◽  
Condensation Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Mixed Metal Oxide ◽  
Solvent Free Conditions

NiMgAl mixed oxide catalyzes nitro-aldol condensation reaction at room temperature under solvent free conditions exhibiting 99% conversion.

P–p heterojunction CuO/CuCo2O4 nanotubes synthesized via electrospinning technology for detecting n-propanol gas at room temperature

2017 ◽  
Vol 4 (7) ◽  
pp. 1219-1230 ◽  
Author(s):  
Khaled Tawfik Alali ◽  
Zetong Lu ◽  
Hongsen Zhang ◽  
Jingyuan Liu ◽  
Qi Liu ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Room Temperature ◽  
Gas Sensing ◽  
Tubular Structure ◽  
Large Specific Surface Area ◽  
Sensing Performance

Composite CuO/CuCo2O4 nanotubes were synthesized by electrospinning technology. The large specific surface area, complex tubular structure, and p–p heterojunction are the potential reasons for the excellent room temperature gas sensing performance toward n-propanol vapor.

Physicochemical Characteristics of ZnS Immobilized on Spherical Activated Carbon for Removing HA(Humic Acid)

2008 ◽  
Vol 569 ◽  
pp. 37-40 ◽  
Author(s):  
Joon Jae Lee ◽  
Jeong Kwon Suh ◽  
Ji Sook Hong ◽  
Jung Min Lee ◽  
Jin Won Park
Keyword(s):  
Humic Acid ◽  
Ion Exchange ◽  
Specific Surface ◽  
Surface Area ◽  
Zinc Content ◽  
Physicochemical Characteristics ◽  
Photochemical Activity ◽  
X Ray ◽  
Bet Specific Surface Area ◽  
Ray Patterns

In this study, spherical activated carbons contained ZnS(Zn-SPAC) were successfully prepared through carbonization/activation processes. Strong acid ion exchange resin as starting material of Zn-SPAC was treated by 0.01 N zinc solution. Ion exchange treatment was performed from one time to three times for controling zinc content. The ion exchanged resins was activated under N2/H2O-vapor atmosphere at 900 °C for 0.5 hr following by carbonization treatment at 700 °C under N2 atmosphere. The Zn-SPAC samples were measured physicochemical characteristics such as X-ray patterns, SEM image, energy dispersive X-ray spectra, BET specific surface area, intensity and zinc content and used to remove humic acid(HA) in batch reactor for measuring photochemical activity. The X-ray patterns were appeared ZnS type. The Zn-SPAC had large BET specific surface area and their shape was spherical with a diameter about 350 ~ 400 μm. When the Zn-SPAC were dosed in UV reactor, the HA removal efficiency increased upto 60 % at 4hr. The order hand, the HA removal efficiency by only UV-C(λmax =254nm) irradiation was not good about 15 %. Therefore, we infer that the Zn-SPAC have good photochemical activity and presented possibility of photocatalyst for water purification.

Sign in / Sign up

Export Citation Format

Share Document