Spray coating of cellulose aerogel particles in a miniaturized spouted bed

AbstractAim of this work is to apply protective and homogeneous shellac coating layers on the surface of hydrophilic open-pore cellulose aerogel particles with low densities ≤ 0.1 g/cm3 and high specific surface areas in the range of ~ 400–450 m2/g while keeping the aerogels’ microstructure intact during processing. For this purpose, an innovative miniaturized spouted bed setup was used. Successful process settings for application of enclosed films on aerogel surfaces without intrusion of coating material into the pores were determined. Precise control of coating layer thickness in the range of 10–50 µm was achieved due to variation of coating solution amount without agglomeration and clogging events occurring during processing. Comparison of bulk densities and specific surface areas before and after coating proved the intactness of the porous structure. Coating of particles loaded with vanillin led to controlled release, enhancing release half-life times from 20 to 1600 min. Overall, a successful strategy for coating of organic low-density aerogels was developed.

Download Full-text

Experimental Investigation of the Adsorption Characteristics of Mixed Coal and Variations of Specific Surface Areas before and after CH4 Adsorption

Applied Sciences ◽

10.3390/app9030524 ◽

2019 ◽

Vol 9 (3) ◽

pp. 524 ◽

Cited By ~ 8

Author(s):

Pengxiang Zhao ◽

Hui Liu ◽

Shugang Li ◽

Haifei Lin ◽

Yongyong Jia ◽

...

Keyword(s):

Specific Surface ◽

Laboratory Tests ◽

Gas Adsorption ◽

Longwall Face ◽

Adsorption Volume ◽

Adsorption Characteristics ◽

Surface Areas ◽

Before And After ◽

Tectonic Coal ◽

Specific Surface Areas

Tectonic coal is a kind of soft coal that is generated during tectonic movement. Gas outbursts usually occur in seams containing both virgin coal and tectonic coal. To reveal the adsorption characteristics of this type of coal seam (containing both virgin coal and tectonic coal), both tectonic coal and virgin coal were collected from the same longwall face and a series of laboratory tests were conducted, including coal sorption tests and pore specific surface measurements. Both the tectonic coal and virgin coal were crushed into coal powder (0.18–0.25 mm) for the coal sorption tests. In these laboratory tests, different mass ratios between tectonic coal and virgin coal were tested. We found that with the increase of the percentage of tectonic coal, the adsorption volume showed a rising trend, reached its maximum value, and then decreased. The specific surface areas of the mixed coal samples had the same evolution trends as those of the adsorption volume. From the laboratory tests, we found that when the mass ratio of virgin coal to tectonic coal was 1:1, both the adsorption volume and the specific surface areas reached their maximum values. Due to the percentage variation of the tectonic coal in the panel with the advancement of the longwall face, when the tectonic coal accounted for 50% of the total coal, the gas content would rise. Thus, proper measures should be adopted for outburst hazards control. The mathematical model between the change of specific surface area and the stress and strain of pore expansion before and after gas adsorption was established, and the relationship between the change of pore structure and gas emission before and after gas adsorption was obtained. It provides a theoretical basis for further research on coal and gas outburst mechanisms.

Download Full-text

Electrospun structures with controlled specific surface areas and pores

57th International Astronautical Congress ◽

10.2514/6.iac-06-c2.4.07 ◽

2006 ◽

Author(s):

Vasana Maneeratana ◽

Wolfgang M. Sigmund

Keyword(s):

Specific Surface ◽

Surface Areas ◽

Specific Surface Areas

Download Full-text

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

RSC Advances ◽

10.1039/c5ra23426c ◽

2016 ◽

Vol 6 (2) ◽

pp. 1253-1259 ◽

Cited By ~ 42

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.

Download Full-text

Experimental Investigation of Coal Dust Wettability Based on Surface Contact Angle

Journal of Chemistry ◽

10.1155/2016/9452303 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8 ◽

Cited By ~ 15

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.

Download Full-text

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

Chemistry of Materials ◽

10.1021/cm903303v ◽

2010 ◽

Vol 22 (4) ◽

pp. 1276-1278 ◽

Cited By ~ 39

Author(s):

Xiaoxing Fan ◽

Ying Wang ◽

Xinyi Chen ◽

Ling Gao ◽

Wenjun Luo ◽

...

Keyword(s):

Specific Surface ◽

Surface Areas ◽

Specific Surface Areas

Download Full-text

Carbon Microspheres Prepared by High Internal Phase Emulsion Polymerization

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.239-242.3105 ◽

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.

Download Full-text

The Experimental Study on Grinding Properties of Gas Quenching Steel Slag

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.612 ◽

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.

Download Full-text

Photocatalytic activity of CaTaO2N nanocrystals obtained from a hydrothermally synthesized oxide precursor

10.31219/osf.io/qdgam ◽

2019 ◽

Author(s):

Roberto Köferstein

Keyword(s):

Photocatalytic Activity ◽

Methyl Orange ◽

Specific Surface ◽

Morphological Properties ◽

Soft Chemistry ◽

Co Catalyst ◽

Surface Areas ◽

Oxide Precursor ◽

Photocatalytic Activities ◽

Specific Surface Areas

Highly crystalline CaTaO2N nanoparticles possessing large specific surface areas were investigated as photocatalysts for the decomposition of methyl orange. Two different Ca2Ta2O7 precursors were synthesized by classical solid state synthesis and a hydrothermal soft-chemistry approach, respectively. In both cases, nitridation was carried out by thermal ammonolysis. The obtained CaTaO2N samples were compared with respect to their optical, thermal and morphological properties as well as their photocatalytic activities. In particular, the influence of ammonolysis temperature on the photocatalytic properties was studied. Using hydrothermally synthesized Ca2Ta2O7, phase pure CaTaO2N was obtained already at a relatively low ammonolysis temperature of 860 °C. Morphological investigations show that the CaTaO2N samples from the hydrothermally synthesized precursor consist of single-crystalline particles of 45 to 70 nm diameter with high specific surface areas between 12 and 19 m2 g-1, depending on ammonolysis temperature. A considerable photocatalytic activity for methyl orange degredation was found for the nanoscaled CaTaO2N particles prepared at lower ammonolysis temperatures. Using CoOx as co-catalyst, a further strong enhancement of the methyl orange decomposition by a factor 5-10 was achieved.

Download Full-text