The Effect of Ultrasonic Radiation on Gelation and Properties of Ormosils

1992 ◽  
Vol 271 ◽  
Author(s):  
Kazuki Monta ◽  
Yi Hu ◽  
John D. Mackenzie
Keyword(s):  
Specific Surface ◽  
Liquid State ◽  
Sol Gel ◽  
Exothermic Reaction ◽  
Ultrasonic Radiation ◽  
Surface Areas ◽  
Organically Modified Silicates ◽  
Organically Modified ◽  
Specific Surface Areas ◽  
Hydrolysis And Polycondensation

ABSTRACTUltrasound has been applied to organically modified silicates (ORMOSILs) solutions during gelation. A series of silica and polydimethylsiloxane (PDMS) composites have been prepared by the sol-gel method. Tetraethoxysilane (TEOS), PDMS, water and a HC1 catalyst were mixed and exposed to 20 kHz ultrasonic radiation under different conditions. Ultrasonic radiation made it possible to obtain wet gels in 5 to 30 min. without solvent (e.g. alcohol, and THF). And exothermic reaction was observed due to hydrolysis and polycondensation of TEO S. The reaction process was examined by liquid state 29Si NM R. Densities of obtained sono-ORMOSILs were observed to be higher than those produced by ordinary processes. Some sono-ORMOSIL samples demonstrated extremely low porosity and low specific surface areas.

scholarly journals Towards Macroporous α-Al2O3—Routes, Possibilities and Limitations

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1787
Author(s):  
Simon Carstens ◽  
Ralf Meyer ◽  
Dirk Enke
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Surface Areas ◽  
Alumina Membranes ◽  
Sol Gel Process ◽  
Specific Surface Areas ◽  
Α Al2o3 ◽  
Sol Gel Synthesis

This article combines a systematic literature review on the fabrication of macroporous α-Al2O3 with increased specific surface area with recent results from our group. Publications claiming the fabrication of α-Al2O3 with high specific surface areas (HSSA) are comprehensively assessed and critically reviewed. An account of all major routes towards HSSA α-Al2O3 is given, including hydrothermal methods, pore protection approaches, dopants, anodically oxidized alumina membranes, and sol-gel syntheses. Furthermore, limitations of these routes are disclosed, as thermodynamic calculations suggest that γ-Al2O3 may be the more stable alumina modification for ABET > 175 m2/g. In fact, the highest specific surface area unobjectionably reported to date for α-Al2O3 amounts to 16–24 m2/g and was attained via a sol-gel process. In a second part, we report on some of our own results, including a novel sol-gel synthesis, designated as mutual cross-hydrolysis. Besides, the Mn-assisted α-transition appears to be a promising approach for some alumina materials, whereas pore protection by carbon filling kinetically inhibits the formation of α-Al2O3 seeds. These experimental results are substantiated by attempts to theoretically calculate and predict the specific surface areas of both porous materials and nanopowders.

Ambient temperature NO oxidation over Cr-based amorphous mixed oxide catalysts: effects from the second oxide components

2017 ◽  
Vol 7 (11) ◽  
pp. 2362-2370 ◽  
Author(s):  
Aiyong Wang ◽  
Bo Lin ◽  
Hanlei Zhang ◽  
Mark H. Engelhard ◽  
Yanglong Guo ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Specific Surface ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Sol Gel ◽  
No Oxidation ◽  
Gel Method ◽  
Mixed Oxide Catalysts ◽  
Surface Areas ◽  
Specific Surface Areas

Three series of Cr-based mixed oxides (Cr–Co, Cr–Fe, and Cr–Ni oxides) with high specific surface areas and amorphous textures were synthesized using a novel sol–gel method.

scholarly journals Variation of Gelatin Amount as Template for Mesoporous Silica-Alumina Synthesis based on Lapindo Mud

2020 ◽  
Vol 32 (7) ◽  
pp. 1575-1580
Author(s):  
R. Nuryanto ◽  
W. Trisunaryanti ◽  
Triyono
Keyword(s):  
Mesoporous Silica ◽  
Specific Surface ◽  
Surface Area ◽  
Sol Gel ◽  
Tem Analysis ◽  
Gel Method ◽  
Sol Gel Method ◽  
Surface Areas ◽  
Silica Alumina ◽  
Specific Surface Areas

The synthesis of mesoporous silica-alumina from Na2SiO3 and NaAlO2 solutions extracted from lapindo mud using mesoporous gelatin templates from catfish bone extract has been performed. Mesoporous silica-alumina (MSA) synthesis was carried out by sol-gel method with a gelatin template of catfish bone for as much as 0.0; 0.5; 1.0 and 1.5 g, which produced MSA-G00, MSA-G05, MSA-G10 and MSA-G15, respectively. The obtained MSA was analyzed using FTIR, XRD, TEM and surface area analyzer (BET and BJH methods). The MSA-G00, MSA-G05, MSA-G10 and MSA-G15 showed a specific surface areas of 24.58, 41.73, 59.73, 89.82 m2/g and pore diameters of 10.20, 3.86, 9.97, and 7.31 nm, respectively. The XRD results proved that all the MSA were amorphous while the TEM analysis showed that all prepared MSAs using gelatin as a template were wormhole-like pores

Preparation of TiO2-based powders with high photocatalytic activities

1997 ◽  
Vol 12 (3) ◽  
pp. 607-609 ◽  
Author(s):  
Tomoko Kasuga ◽  
Masayoshi Hiramatsu ◽  
Masayoshi Hirano ◽  
Akihiko Hoson ◽  
Kyoko Oyamada
Keyword(s):  
Specific Surface ◽  
Sol Gel ◽  
Photocatalytic Property ◽  
Reflection Spectra ◽  
Gel Method ◽  
Sol Gel Method ◽  
Surface Areas ◽  
Infrared Reflection ◽  
Photocatalytic Activities ◽  
Specific Surface Areas

TiO2-based powders doped with a small amount of SiO2 were prepared by a sol-gel method and subsequently were heated to precipitate fine anatase crystals. Although the obtained powders have large specific surface areas (≈200 m2 · g−1), they showed poorer activity in a photocatalytic property than the undoped TiO2 powders which have the area of 50 m2 · g−1. The SiO2-doped TiO2 powders were treated chemically with aqueous NaOH. Infrared reflection spectra showed that the treatment reduced the amount of SiO2 in the powders. The photocatalytic property of the powders was extremely improved by the treatment, and the powders showed higher activity than the undoped TiO2 powders.

scholarly journals Ultrafine porous boron nitride nanofibers synthesized via a freeze-drying and pyrolysis process and their adsorption properties

RSC Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 1253-1259 ◽  
Author(s):  
Jing Lin ◽  
Lulu Xu ◽  
Yang Huang ◽  
Jie Li ◽  
Weijia Wang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Specific Surface ◽  
Freeze Drying ◽  
Adsorption Properties ◽  
Pyrolysis Process ◽  
Surface Areas ◽  
Aspect Ratios ◽  
Large Pore ◽  
Specific Surface Areas

Ultrafine porous boron nitride nanofibers with high aspect ratios, high specific surface areas and large pore volumes has been synthesized in large quantity via a freeze-drying and post pyrolysis process.

scholarly journals Experimental Investigation of Coal Dust Wettability Based on Surface Contact Angle

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Gang Zhou ◽  
Han Qiu ◽  
Qi Zhang ◽  
Mao Xu ◽  
Jiayuan Wang ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Specific Surface ◽  
Coal Dust ◽  
Single Point ◽  
Contact Angles ◽  
Critical Surface ◽  
Volume Percentage ◽  
Surface Areas ◽  
Specific Surface Areas

Wettability is one of the key chemical properties of coal dust, which is very important to dedusting. In this paper, the theory of liquid wetting solid was presented firstly; then, taking the gas coal of Xinglongzhuang coal mine in China as an example, by determination of critical surface tension of coal piece, it can be concluded that only when the surface tension of surfactant solution is less than 45 mN/m can the coal sample be fully wetted. Due to the effect of particle dispersity, compared with the contact angle of milled coal particle, not all the contact angles of screened coal powder with different sizes have a tendency to increase. Furthermore, by the experiments of coal samples’ specific surface areas and porosities, it can be achieved that the volume of single-point total pore decreases with the gradual decreasing of coal’s porosity, while the ultramicropores’ dispersities and multipoint BET specific surface areas increase. Besides, by a series of contact angle experiments with different surfactants, it can be found that with the increasing of porosity and the decreasing of volume percentage of ultramicropore, the contact angle tends to reduce gradually and the coal dust is much easier to get wetted.

Facile Method To Synthesize Mesoporous Multimetal Oxides (ATiO3, A = Sr, Ba) with Large Specific Surface Areas and Crystalline Pore walls

2010 ◽  
Vol 22 (4) ◽  
pp. 1276-1278 ◽  
Author(s):  
Xiaoxing Fan ◽  
Ying Wang ◽  
Xinyi Chen ◽  
Ling Gao ◽  
Wenjun Luo ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Areas ◽  
Specific Surface Areas

Carbon Microspheres Prepared by High Internal Phase Emulsion Polymerization

2011 ◽  
Vol 239-242 ◽  
pp. 3105-3108
Author(s):  
Ming Xian Liu ◽  
Li Hua Gan ◽  
Jun Hu ◽  
Hong Lai Liu ◽  
Long Wu Chen
Keyword(s):  
Electron Microscopy ◽  
Specific Surface ◽  
Aqueous Phase ◽  
Apparent Density ◽  
Tween 80 ◽  
Carbon Microspheres ◽  
High Internal Phase Emulsion ◽  
Surface Areas ◽  
Internal Phase ◽  
Specific Surface Areas

In this paper, we present a novel approach for the synthesis of carbon microspheres via the polymerization of a high internal phase emulsion (HIPE). By using Span 80 and Tween 80 as emulsifiers, 1iquid paraffin as oil phase, and the mixture of resorcinol/formaldehyde (R/F) solution as aqueous phase, an O/W emulsion was obtained. This emulsion phase inverted to a W/O HIPE induced by ammonia which served as the polymerization catalyst. Carbon microspheres (CMs) were prepared by polymerization of the HIPE, followed by drying and carbonization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analyzer were used to characterize as-prepared CMs. The results indicate that, in case of 0.25 wt% ammonia of the HIPE, the diameters of CMs decreased from about 2 to 1 μm when the mass fraction of aqueous R/F decreased from 0.714 to 0.357; the apparent density and the specific surface areas of the CMs, however, did not change obviously, which are about 0.6 g/cm3and 200 m2/g, respectively. The dosage of ammonia has a significant influence on the morphology and properties of CMs. With increasing of the ammonia mass to 1 wt% of the HIPE, the resultant carbon materials comprise not only CMs, but also some carbon sheets; the apparent density of which increased to 0.9 g/cm3and the specific surface areas of which decreased to below 100 m2/g. In addition, the other parameters for CMs preparation were also investigated. It was found that the proper conditions were controlling the temperature of 303-333 K and the oil/aqueous phase mass ratio of 2.5:7.

The Experimental Study on Grinding Properties of Gas Quenching Steel Slag

2011 ◽  
Vol 189-193 ◽  
pp. 612-617
Author(s):  
Hong Wei Xing ◽  
Yue Long ◽  
Xiu Li ◽  
Gao Liang Li ◽  
Yu Zhu Zhang ◽  
...  
Keyword(s):  
Specific Surface ◽  
New Technology ◽  
Steel Slag ◽  
Economic Benefits ◽  
Surface Areas ◽  
Mineral Phases ◽  
Quenching Process ◽  
Gas Quenching ◽  
Specific Surface Areas ◽  
Better Than

A gas quenching process to deal with steel slag and its characteristics of the new technology was briefly introduced. The grinding characteristics, mineral phases of gas quenching steel slag and the potential economic benefits of using it as cement mixing material was studied by compared to heat-stew steel slag. The results indicated that the specific surface areas (S) and grinding times (t) of the gas quenching steel slag showed a first order exponential decay relationship. With the extension of time, the specific surface areas of heat-stew steel slag was tending to balance earlier than that of gas quenching steel slag; The energy consumption of gas quenching steel slag was much lower than that of heat-stew steel slag. Gas quenching steel slag was comprised of C2S, C3S, a certain amount of (Ca2(Al, Fe)2O5）and RO phase, but the content of RO phase was relatively low, which increased the grindability of the quenching steel slag, so that the grindability of gas quenching steel slag was much better than that of heat-stew steel slag. Gas quenching steel slag prepared for cement addictives would bring great economic benefits.

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