Superhydrophobic and oleophobic ultra-fine dry chemical agent with higher chemical activity and longer fire-protection

Zhao, Junchao; Yin, Zhitao; Shahid, Muhammad; Xing, Haoran; Cheng, Xiaomin; Fu, Yangyang; Lu, Song

doi:10.1016/j.jhazmat.2019.05.018

Cited by 40 publications

(19 citation statements)

References 39 publications

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“…As shown in Figure 3 a, for silica aerogels after heat treatment at different temperatures, in the spectrum, peak of ~960 cm −1 were observed for the sample heat treated at 400 °C, which was due to the stretching vibration of Si–OH [ 26 ] and it disappeared after 800 °C. The peak of ~2973 cm −1 , ~2911 cm −1 and ~1260 cm −1 from the stretching, bending and deformation vibration of C–H bonds of Si–CH 3 groups, respectively [ 27 , 28 ], gradually became weaker and eventually could not be observed after 800 °C. The changes of peaks indicated that when the silica aerogel was pyrolyzed, Si–CH 3 was oxidized and Si–OH was produced.…”

Section: Resultsmentioning

confidence: 99%

Improvement of the Thermal Insulation Performance of Silica Aerogel by Proper Heat Treatment: Microporous Structures Changes and Pyrolysis Mechanism

Lun

Gong

Zhang

et al. 2022

Gels

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A simple heat treatment method was used to optimize the three-dimensional network structure of the hydrophobic aerogel, and during the heat treatment process at 200–1000 °C, the thermal conductivity of the aerogel reached the lowest to 0.02240 W/m·K between 250 °C and 300 °C, which was mainly due to the optimization of microstructure and pyrolysis of surface groups. Further Fluent heat-transfer simulation also confirmed the above results. Synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was used to finely measure the pyrolysis process of aerogels, and the pyrolysis process of aerogel was divided into four stages. (I) Until 419 °C, as the temperature continued to rise, surface methyl groups were oxidized to form hydroxyl. (II) As the temperature reached to 232 °C, the oxidation proceeded. In addition, inside the aerogel, because of lacking oxygen, the reaction produced CH4 and C–Si bonds would form. (III) After 283 °C, Si–OH groups began to condense to form Si–O–Si, which optimized the three-dimensional network structures to be beneficial to improve the thermal insulation performance of silica aerogel. (IV) When it reached 547 °C, the chemical reaction was terminated, and all the primary particles gradually fused into secondary particles and sintered to form clusters.

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Section: Resultsmentioning

confidence: 99%

Improvement of the Thermal Insulation Performance of Silica Aerogel by Proper Heat Treatment: Microporous Structures Changes and Pyrolysis Mechanism

Lun

Gong

Zhang

et al. 2022

Gels

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“…Sredstva kao što su voda, pena i CO 2 gas nije moguće koristiti za sve vrste požara. Uvođenjem SGP u formi praha eliminisani su skoro svi nedostaci ranije korišćenih sredstava, a što je najvažnije postignuta je velika moć gašenja koja se ogleda u trenutnoj eliminaciji plamena [1][2][3]. Praktična primena praškastih materijala za gašenje požara počela je pojavom prvih ručnih aparata za gašenje požara prahom.…”

Section: Uvodunclassified

Optimization of the active component grinding process and hydrophobization of the obtained powder fire extinguisher

Mihajlovic

Đorđević

Jovanović

et al. 2021

Hem Ind

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This work presents a grinding process of monoammonium phosphate (MAP) as an active component in a powder fire extinguisher (PFE). The aim was to determine the grinding time for reaching the optimal particle size of MAP necessary for permanent fire extinguishing. MAP grinding was performed by using a laboratory ceramic ball mill and a vibrating cup mill. The grinding process was controlled by sieving using a 100 ?m sieve at precisely defined time intervals. The efficiency of a PFE depends on the share of the -100 ?m fraction of the active component, which has to exceed 60 %. The optimal grain size with 64 % of fraction of particle size -100 ?m was obtained after 33 min of grinding of ?3000 ?m mm grain size MAP by using a ball mill (single-stage grinding). In two-stage process, by grinding the same initial MAP sample (?3000 ?m) in the vibro mill for 10 min, powder with the upper limit grain size of 300 ?m and the mean grain diameter of 120 ?m was obtained. This sample with a reduced size was further ground in the ceramic ball mill yielding 67.5 % of the fraction of particle size -100 ?m after 19 min. The total time of the two-stage grinding process was 29 min. By analyzing the grinding time of MAP required to get the lowest required share of the fraction of particle size -100 ?m that provides the effectiveness of formed PFE it can be concluded that 64 % of this fraction was obtained after 33 min of single-stage grinding, while only after 26 min in the two-stage process. Thus, the grinding time was reduced by 7 min indicating certain energy savings. Stability and hydrophobicity of the obtained PFE were achieved by coating with magnesium stearate (MgSt) at the content of 2 % in a ball mill for 15 min. The coating was confirmed by the standardized procedure for verification of PFE hydrophobic properties in contact with water drops. To obtained PFE had component mass ratios of MAP:AS:CC:QS:MgSt=55:20:18:5:2 (AS-ammonium sulfate; CC-calcium carbonate, QS-quartz sand) and was further characterized by chemical and granulometric analyses. The fire extinguishing efficiency of the PFE was tested in controlled conditions, whereby fires were initiated by burning solid materials and flammable liquids. In both cases, immediate elimination of flames was achieved, thus proving the efficiency of the PFE obtained in this work for practical applications.

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“…Their study revealed that the interfacial shear strength increased by 36.52% compared with that of the original glass fiber composites. Zhao et al fabricated a superoleophobic dry chemical agent for the re-ignition of pool fires [124]. The dry chemical agent can splashed onto oils to prevent oil evaporation, which can quickly quench pool fires.…”

Section: Other Cemsmentioning

confidence: 99%

Superhydrophobic Civil Engineering Materials: A Review from Recent Developments

Xiang

Fang

et al. 2019

Coatings

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Superhydrophobic surfaces have drawn attention from scientists and engineers because of their extreme water repellency. More interestingly, these surfaces have also demonstrated an infinite influence on civil engineering materials. In this feature article, the history of wettability theory is described firstly. The approaches to construct hierarchical micro/nanostructures such as chemical vapor deposition (CVD), electrochemical, etching, and flame synthesis methods are introduced. Then, the advantages and limitations of each method are discussed. Furthermore, the recent progress of superhydrophobicity applied on civil engineering materials and its applications are summarized. Finally, the obstacles and prospects of superhydrophobic civil engineering materials are stated and expected. This review should be of interest to scientists and civil engineers who are interested in superhydrophobic surfaces and novel civil engineering materials.

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Superhydrophobic and oleophobic ultra-fine dry chemical agent with higher chemical activity and longer fire-protection

Cited by 40 publications

References 39 publications

Improvement of the Thermal Insulation Performance of Silica Aerogel by Proper Heat Treatment: Microporous Structures Changes and Pyrolysis Mechanism

Improvement of the Thermal Insulation Performance of Silica Aerogel by Proper Heat Treatment: Microporous Structures Changes and Pyrolysis Mechanism

Optimization of the active component grinding process and hydrophobization of the obtained powder fire extinguisher

Superhydrophobic Civil Engineering Materials: A Review from Recent Developments

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