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Journal ArticleDOI: 10.1016/J.JHAZMAT.2020.124216

Insight to hydrophobic SiO2 encapsulated SiO2 gel: Preparation and application in fire extinguishing.

05 Mar 2021-Journal of Hazardous Materials (Elsevier)-Vol. 405, pp 124216
Abstract: Micron-sized hydrophobic SiO2 encapsulated SiO2 gel (HSESG) was prepared successfully by using SiO2 gel as the solid core and hydrophobic nano-SiO2 particle as the shell under high-speed shear stirring. The flowability, stability, particle size distribution, bulk density and water repellency of the powder were measured separately, and it was concluded that this type of product can exhibit smaller static angle, larger flow rate and lower bulk density. After the formation of a stable spatial network of SiO2 gel in its interior, relevant fire extinguishing experiments were carried out and HSESG exhibits higher efficiency in suppressing wood stack fires than that of ordinary dry water (DW) and ABC dry powder. As a high-efficiency fire-extinguishing material, it also exhibits excellent environmental friendliness and non-toxicity, which will make it have the potential to develop a new application market.

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Topics: Dry water (56%), Particle (50%)

10 results found

Journal ArticleDOI: 10.1016/J.FUEL.2020.120121
Qi Zhao1, Jing Liu1, Chuyuan Huang1, Hongming Zhang  +3 moreInstitutions (1)
01 May 2021-Fuel
Abstract: To investigate the flame propagation of coal dust deflagration and the inhibition characteristics of coal ash which as a mixed inert powder under the atmosphere of methane. A vertical combustion pipe with half-open was built to study the methane/coal dust deflagration at different concentrations of coal dust and different mass fractions of coal ash. The residues after coal dust deflagration were characterized by SEM, XPS and FTIR. Results indicate that the deflagration intensity of coal dust firstly increases and then decreases with the increasing of coal dust concentration. Under this experimental conditions with 7 vol% methane/air, the optimum deflagration phenomenon appears at the dust concentration of 200 g/m3. After the addtion of coal ash, the decomposition of coal dust was prevented to some extent for its heat resistance and absorption. The intensity of methane/coal dust deflagration was weakened with the increasing of coal ash mass fraction. In addition, the inhibition mechanisms of coal ash on coal dust deflagration were summarized based on the material analysis of the deflagration residues.

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Topics: Coal dust (75%), Deflagration (57%), Fly ash (57%) ... show more

12 Citations

Journal ArticleDOI: 10.1016/J.CEJ.2020.128286
Song He1, Guibin Shi1, Huan Xiao1, Guoxiang Sun1  +6 moreInstitutions (1)
Abstract: In this study, lignin-based pitch extracted from black liquor was used as the precursor for synthesis of activated carbon (AC) with high specific surface area and pore volume through chemical activation with potassium hydroxide (KOH). The effect of the activation temperature on AC properties was also explored. The optimized activated carbon (PAC-5-850-60) was prepared at the activation temperature of 850 °C. At this temperature, the specific surface area and total pore volume of PAC-5-850-60 reached the maximum values of 3652 m2·g−1 and 2.35 cm3·g−1, respectively. The physicochemical properties and structural characteristics of ACs were characterized by N2 adsorption/desorption, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectrometry (FTIR) and X-ray photoelectron spectroscopy (XPS). In the adsorption study, gaseous benzene was selected as the adsorbate. Dynamic adsorption experiment was carried out to explore the adsorption behavior and mechanism of PACs. Under 5000 ppm (or 500 Pa partial pressure), the adsorption capacity and partition coefficient for gaseous benzene on PAC-5-850-60 were 802.06 mg g−1, and 0.20 mol kg−1Pa−1 at 10% breakthrough level and 819.77 mg g−1, and 0.02 mol kg−1Pa−1 at 100% breakthrough level. PAC-5-850-60 exhibited favorable recycling adsorption performance and could be a good absorbent for removal of gaseous benzene.

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Topics: Adsorption (62%), Activated carbon (58%), Specific surface area (57%) ... show more

12 Citations

Journal ArticleDOI: 10.1016/J.FUEL.2021.120954
Xiaotong Wang1, Xiaotong Wang2, Huaming Dai1, Guangqian Liang1  +6 moreInstitutions (2)
15 Sep 2021-Fuel
Abstract: The leakage of pulverized coal easily results in fire and explosion accidents during coal gasification process. A vertical pipeline was built with the high-speed camera, micro-thermocouple and pressure sensor to obtain the characteristics of flame propagation. Based on the atmosphere of coal gasification, the effects of the spraying time, particle conditions, and rank of the pulverized coal were studied. The results show that the peak temperature, combustion pressure and velocity increase first and then decrease with the increasing of spraying time. When the particle size pulverized coal is 200 mesh, the peak pressure reaches the highest value. The flame propagation characteristics are similar at different concentrations of pulverized coal and the maximum appears at 333 g/m3. In addition, the peak temperature of the pulverized coal flame increases with the increasing of the proportion of long-flame coal in the mixed coal. The optimum characteristics of flame propagation appear at different ratios of mixed coal due to the effect of coal rank.

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Topics: Coal (68%), Pulverized coal-fired boiler (67%), Coal gasification (57%) ... show more

6 Citations

Journal ArticleDOI: 10.1016/J.CEJ.2021.130184
Guanyu Chen1, Song He1, Guibin Shi1, Yuansheng Ma1  +7 moreInstitutions (2)
Abstract: Metal-organic framework (MOF) materials have been extensively studied in the removal of pollutants in wastewater. However, MOFs, which are usually in powder form, suffer from complex separation that hinder their practical application. Herein, a composite adsorbent material, ZIF-67@WA (wood aerogel), has been successfully fabricated through in-situ anchoring of ZIF-67 rhombic dodecahedron on the wood aerogel obtained by selectively removing lignin and hemicellulose from natural wood. WA with lamellar structure provided sufficient attachment sites for ZIF-67, and the content of ZIF-67 in the composite reached 32.65 wt%. ZIF-67 with 1 μm in grain size maintained its crystallinity when it was introduced to the surface of WA. The effects of pH, contact time, initial concentration, temperature, coexisting ions and humic acid on tetracycline (TC) adsorption were investigated. The composite showed excellent TC adsorption capacity (273.84 mg·g−1 at 298 K), which was comparable to most previously reported adsorbents. Pseudo-second-order kinetic model and Langmuir isotherm model described the adsorption process well. Adsorption thermodynamic studies implied that the adsorption process was spontaneous and endothermic. Furthermore, the possible adsorption mechanism was proposed. The TC removal efficiency dropped from 94.09% to 80.27% after 3 cycles, revealing the composite could be recycled. The leaching of cobalt was measured to be within the permissible range, indicating that no serious secondary contamination would be caused during using the composite. The superior adsorption performance coupled with compressibility, light weight and facile separation gave ZIF-67@WA the potential to effectively remove TC from water.

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Topics: Adsorption (60%), Langmuir adsorption model (55%), Aerogel (51%)

5 Citations

Journal ArticleDOI: 10.1016/J.COLSURFA.2020.126053
Guibin Shi1, Chichi Ruan1, Song He1, Hongjie Pan  +5 moreInstitutions (1)
Abstract: A novel and flexible paper-based filtration material, namely Zirconium-based metal-organic framework @ carboxymethylated filter paper (CMP-UiO-66), was synthesized in this work. The CMP-UiO-66 was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS mapping), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectrometry (FTIR) and thermogravimetric analysis (TGA). The removal performance and corresponding mechanisms were evaluated with the help of a batch experiments under different conditions, FTIR, isotherm models and thermodynamics studies. The Langmuir isotherm model can accurately describe the removal process under the initial concentrations from 10 to 50 mg/L. The values of thermodynamics parameters were positive standard entropy (ΔS) and standard enthalpy (ΔH) values, but negative standard Gibbs free energy (ΔG), indicating a random, endothermic and spontaneous process. The removal mechanisms which were made of physical interactions (fibers obstruction and pores filling) and chemical interactions (hydrogen bonding, electrostatic attraction, π-π and n-π interactions), synthetically played a role in the removal process. The CMP-UiO-66 exhibited the excellent removal efficiencies and partition coefficients toward methylene blue (MB) dye for a wide range of pH via simple filtration. Compared with powder-type absorbents, CMP-UiO-66 which possessed the favorable reusability, simplicity and rapidity can be considered as a promising adsorbent for effectively capturing the MB dye molecules. It could also be reused after a simple washing process. This work may provide an effective method for capturing the MB dye molecules by a simple filtration step of the dye solution in the short time, without causing secondary pollution.

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4 Citations


38 results found

Journal ArticleDOI: 10.1038/NMAT1757
Bernard P. Binks1, Ryo Murakami1Institutions (1)
15 Oct 2006-Nature Materials
Abstract: Small particles attached to liquid surfaces arise in many products and processes, including crude-oil emulsions and food foams and in flotation, and there is a revival of interest in studying their behaviour. Colloidal particles of suitable wettability adsorb strongly to liquid-liquid and liquid-vapour interfaces, and can be sole stabilizers of emulsions and foams, respectively. New materials, including colloidosomes, anisotropic particles and porous solids, have been prepared by assembling particles at such interfaces. Phase inversion of particle-stabilized emulsions from oil in water to water in oil can be achieved either by variation of the particle hydrophobicity (transitional) or by variation of the oil/water ratio (catastrophic). Here we describe the phase inversion of particle-stabilized air-water systems, from air-in-water foams to water-in-air powders and vice versa. This inversion can be driven either by a progressive change in silica-particle hydrophobicity at constant air/water ratio or by changing the air/water ratio at fixed particle wettability, and has not been observed in the corresponding systems stabilized by surfactants. The simplicity of the work is that this novel inversion is achieved in a single system. The resultant materials in which either air or water become encapsulated have potential applications in the food, pharmaceutical and cosmetics industries.

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Topics: Dry water (57%), Particle (57%), Phase inversion (56%)

522 Citations

Journal ArticleDOI: 10.1021/JA8048173
Abstract: Dry water stores 175 v(STP)/v methane at 2.7 MPa and 273.2 K in a hydrate form which is close to the Department of Energy volumetric target for methane storage. Dry water is a silica-stabilized free-flowing powder (95% wt water), and fast methane uptakes were observed (90% saturation uptake in 160 min with no mixing) as a result of the relatively large surface-to-volume ratio of this material.

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Topics: Methane (59%), Dry water (58%), Hydrate (54%) ... show more

246 Citations

Journal ArticleDOI: 10.1016/S0009-2509(03)00137-4
Andrea C. Santomaso1, P Lazzaro1, Paolo Canu1Institutions (1)
Abstract: The propensity of powders to flow under given circumstances (flowability) affects a large number of industrial applications. A single, reliable and widely applicable flowability test does not exist, because of the variety of both granular materials and influence of handling on the measurements results. Here we critically examined the results provided by Hausner's method, based on apparent densities ratio, with several granular materials. Major limitations appeared to be the achievement and measurement of a dense packing condition, provided by the tapped density in the Hausner's ratio. After a detailed discussion of standard and modified techniques to measure bulk density, we eventually suggest a new flowability criterion based on a novel technique to determine a high packing density. The proposed criterion is more sensitive to differences in flowability, as quantified by the repose angle. In order to investigate also the domain of cohesive powders, we developed a novel procedure to measure the repose angle of such powders. Eventually, the new criterion was able to account consistently for free-flowing and cohesive powders. It also stimulates the discussion on subtle issues involved in the determination and use of elementary powder's properties.

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Topics: Angle of repose (57%)

193 Citations

Journal ArticleDOI: 10.1016/J.CES.2008.01.014
Cláudio P. Ribeiro1, Paulo L.C. Lage1Institutions (1)
Abstract: Clathrate hydrates have drawn considerable attention in the last few years due to a variety of possible applications, including transportation and storage of natural gas and carbon dioxide sequestration in the ocean. These applications require the development of effective hydrate formation reactors, which, in turn, asks for a comprehensive understanding of hydrate formation kinetics. Contrary to hydrate thermodynamics, hydrate kinetics are still poorly understood. In the present contribution, a critical review of the literature on hydrate kinetics is provided, with special emphasis upon modelling efforts, essential to the design of any reactor. The main features of the models available in the literature for hydrate nucleation and growth are discussed, together with their limitations. In addition, suggestions for further developments are presented.

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Topics: Hydrate (54%), Clathrate hydrate (54%)

186 Citations

Journal ArticleDOI: 10.1021/LA903120P
Benjamin O. Carter1, Weixing Wang1, Weixing Wang2, Dave J. Adams1  +1 moreInstitutions (2)
02 Mar 2010-Langmuir
Abstract: “Dry water” (DW) is a free-flowing powder prepared by mixing water, hydrophobic silica particles, and air at high speeds. We demonstrated recently that DW can be used to dramatically enhance methane uptake rates in methane gas hydrate (MGH). Here, we expand on our initial work, demonstrating that DW can be used to increase the kinetics of formation of gas clathrates for gases other than methane, such as CO2 and Kr. We also show that the stability of the system toward coalescence can be increased via the inclusion of a gelling agent to form a “dry gel”, thus dramatically improving the recyclability of the material. For example, the addition of gellan gum allows effective reuse over at least eight clathration cycles without the need for reblending. DW and its “dry gel” modification may represent a potential platform for recyclable gas storage or gas separation on a practicable time scale in a static, unmixed system.

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Topics: Dry water (59%), Methane (55%), Gas separation (54%)

127 Citations

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