JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2020
·
IF 2.369
Feifan Chen,Bo Zhang,Luxia Yin,Yongkang Lu,Wanhui Gong,Jianguang Gao,Zekai Zhang,Wensheng Ning
Amine-modified SiO2 hybrid aerogel desulfurization adsorbents with varied Si/N molar ratios (SiO2-NH2-n) were prepared via the sol–gel method followed by the atmospheric drying technique. SiO2-NH2-n aerogels were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), in situ Fourier transform infrared (FT-IR), and N2 adsorption–desorption. The desulfurization performances of SiO2-NH2-n were studied by the batch and breakthrough adsorption experiments. SiO2-NH2-n exhibited an obvious improvement in adsorption capacity for thiophenics compared with SiO2 aerogel due to the hydrogen bonding between thiophenics and amino groups. Among them, SiO2-NH2-8 had the best performance, and the adsorption capacities for thiophene, benzothiophene, and dibenzothiophene were 6.8, 9.5, and 10.2 mg S/gads, respectively. No effect of toluene and cyclohexene on the adsorption of SiO2-NH2-8 for thiophene was observed. The equilibrium adsorption data of SiO2-NH2-8 for thiophene were well fitted by the Freundlich model, indicating that multilayer adsorption occurred on the heterogenetic surface of SiO2-NH2-8. The kinetic adsorption data of SiO2-NH2-8 for thiophene could correlate properly with the pseudo-second-order kinetic model, suggesting that the rate-controlling steps involve surface adsorption. The saturated SiO2-NH2-8 could be regenerated completely via heating at 393 K for 12 h, and the regenerated SiO2-NH2-8 afforded 100% breakthrough adsorption capacity for thiophene.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Gels
·
2022
·Vol. 8
·期 11
·744
·
IF 4.432
Baolu Shi,Long Xie,Bin Ma,Zhiliang Zhou,Baosheng Xu,Lijie Qu
SiO2aerogels have attracted extensive attention due to their unique structural characteristics, which exhibit many special properties, especially good optical transparency. As far as we know, the sol-gel stage during the synthesis of aerogel plays an important role in the construction of the gel skeleton. In this study, we adjusted the amount of silicon source and catalyst to explore the best scheme for preparing highly transparent SiO2aerogels, and further clarify the effects of both on the properties of SiO2aerogels. Results indicated that the pore size distribution was between 10 and 20 nm, the thermal conductivity was between 0.0135 and 0.021 W/(m·K), and the transmittance reached 97.78% at 800 nm of the aerogels, better than most studies. Therefore, it has the potential to be used in aerogel glass for thermal insulation.Keywords:SiO2aerogels;high transparency;thermal insulation;mesoporous materials
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MOLECULES
·
2019
·Vol. 24
·期 21
·3931
·
IF 3.06
Yuxiang Wang,Zeyu Kao,Ting Zhang,Yujun Zhang,Lili Qin,Zhihua Zhang,Bin Zhou,Guangming Wu,Jun Shen,Ai Du
The trans-resveratrol (RSV)-loaded silica aerogel (RLSA) was prepared by the sol-gel method, adding the drug during the aging process, solvent replacement and freeze drying. A series of characterizations showed that RSV stays in the silica aerogel in two ways. First, RSV precipitates due to minimal solubility in water during the solvent replacement process. After freeze drying, the solvent evaporates and the RSV recrystallizes. It can be seen from scanning electron microscope (SEM) and transmission electron microscope (TEM) images that the recrystallized RSV with micron-sized long rod-shaped is integrated with the dense silica network skeleton. Second, from small-angle X-ray scattering (SAXS) results, a portion of the RSV molecules is not crystallized and the size is extremely small. This can be attached to the primary and secondary particles of silica to enhance its network structure and inhibit shrinkage, which is why the volume and pore size of RLSA is larger. In addition, the diffusion of RSV in silica alcogel was studied by a one-dimensional model. The apparent diffusion coefficients of inward diffusion, outward diffusion and internal diffusion were calculated by fitting the time- and position-dependent concentration data. It was found that the outward diffusion coefficient (5.25 × 10−10m2/s) is larger than the inward (2.93 × 10−10m2/s), which is probably due to the interface effect. The diffusion coefficients obtained for different concentrations in the same process (inward diffusion) are found to be different. This suggests that the apparent diffusion coefficient obtained is affected by molecular adsorption.Keywords:RLSA;one-dimension diffusion;alcogel;adsorption/desorption;Silica Aerogel
研究领域:
药学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Huafei Cai,Yonggang Jiang,Jian Feng,Qu Chen,Sizhao Zhang,Liangjun Li,Junzong Feng
Silica aerogel is a typical nanoporous material exhibiting excellent thermal insulation property, and its nanostructure change at high temperature has attracted extensive attention. However, there is a lack of real-time research on the nanostructure evolution of silica aerogel under rapid heating. Here, silica aerogel was rapidly heated and imaged via an in-situ heating TEM to characterize the nanostructure evolution of from 600 °C to 1300 °C. After rapid heating at different temperatures, the silica aerogels were characterized by SEM, BET, TG-DSC, XRD and FT-IR. The nanostructure evolution of the aerogels can be divided into three temperature stages and experimental strategies for inhibiting aerogel shrinkage at high temperature can be provided. In stage Ⅰ (600 °C–1000 °C), the shrinkage of the silica aerogels occurred during the initial time of the heating process (within 2 h), and then the structure of silica aerogel became stable. The shrinkage of silica aerogels is primarily caused by the fusion of secondary particles, and increasing the secondary silica aerogel particle size may contribute to reducing the aerogel shrinkage. In stage Ⅱ (1100 °C), the aerogel shrinkage can be observed all the time with the heating process continues, and finally closed to the dense state. The shrinkage of silica aerogels is caused by the fusion of secondary particles and the macropore collapse, increasing the particle size and reducing the macropore content may slow down aerogel shrinkage. In stage Ⅲ (1200 °C–1300 °C), the aerogel will shrink rapidly and reach a dense state in a very short time (within 0.5 h). The shrinkage of silica aerogels is caused by the rapid pore collapse and the rapid fusion and shrinkage of the secondary particles of the aerogel, and pure silica aerogels cannot be used at this temperature.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Sustainable Cement-Based Materials
·
2024
·
IF 4.7
Jinzhu Tang,Guangxu Ju,Tingyun Zheng,Rui Liang,Guoxing Sun
Silica aerogels (SA) have exceptional thermal insulation capabilities, however, their superhydrophobic nature hinders the formation of a uniform composite when combined with cement slurry. To address this issue, an aqueous solution was employed to disperse SA particles using sodium dodecyl sulfate (SDS). Subsequently, the dispersed micelles were coated with polydopamine (PDA) through in situ polymerization. This approach effectively enhanced the dispersion of SA in cement slurry and improved its connection force with the cement hydration products, thereby mitigating the adverse effects of aggregated SA on the mechanical properties of the cement composite. The successful PDA coating led to the formation of smaller aggregated micelles, resulting in a 30% improvement in compressive strength of cement composites containing modified SA compared to those using unmodified SA, while maintaining the desired thermal conductivity properties. With a strategic increase in the quantity of modified SA, a remarkable thermal conductivity of 0.1351 W/m·K was achieved without significantly compromising the compressive strength, which reached about 13.94 MPa. This enhanced compressive strength surpassed that of conventional thermal insulation materials like expanded polystyrene (EPS) and foam concrete. Consequently, this novel technique has the potential to markedly enhance the thermal insulation of cement composites without excessively impacting their compressive strength, thus contributing to the development of green insulation and energy-saving building materials.
研究领域:
材料科学
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土木工程
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热绝缘
·
建筑材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POROUS MATERIALS
·
2024
·
IF 2.5
Liu Quan,Kong Yong,Shen Xiaodong
This study aims to develop a hydrophobic silica aerogel with high specific surface area and pore volume for thermal insulation under humid and high temperature conditions. Silica aerogels are synthesized through the co-condensation of methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS). The effect of MTES/TEOS ratio on chemical structure, hydrophobicity, and pore structure is investigated. The silica aerogel with a MTES/TEOS molar ratio of 1.4 (MT1.4) exhibits the highest water contact angle of 134°, in addition to a surface area of 1052 m 2 /g and a pore volume of 3.17 cm 3 /g. Excessive MTES results in a slight decrease in water contact angle as well as a significant reduction in specific surface area and pore volume. MT1.4 retains a water contact angle of 101° at 300 °C and a specific surface area of 695 m 2 /g at 500 °C. The thermal conductivity of MT1.4 is as low as 0.0182 W/(m·K) at 25 °C. In the long term up to 42 d, the liquid water and moisture sorption capacities of MT1.4 are as low as 1.9 wt% and 4.7 wt%, respectively. The thermal conductivity hardly changes after water soaking and hygrothermal aging for 42 d. Compared to its state-of-the-art counterparts, MT1.4 offers significant advantages in term of pore structure, thermal stability, thermal insulation, and water resistance, and thus shows great promise for thermal insulation under humid and high temperature conditions.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2024
·Vol. 17
·期 11
·2641
·
IF 3.1
Jinjing Guo,Kaiqiang Luo,Wenqi Zou,Jun Xu,Baohua Guo
Ambient pressure drying (APD) of silica aerogels has emerged as an attractive method adapting to large-scale production. Spring-back is a unique phenomenon during APD of silica aerogels with volume expansion after its shrinkage under capillary force. We attribute the intense spring-back at elevated drying temperatures to a dense structure formed on the surface and the formation of positive internal pressure. Furthermore, an APD-assisted foaming method with an in situ introduction of NH4HCO3was proposed. NH4HCO3decomposing at drying temperatures hastened the emergence of positive pressure, thereby increasing the expansion volume. Compared to the previous method, the porosity of silica aerogel increased from 82.2% to 92.6%, and mesopore volume from 1.79 cm3g−1to 4.54 cm3g−1. By adjusting the amount of the silicon source, silica aerogels prepared by the APD-assisted foaming method generated higher volume expansion and lower thermal conductivity. After calcination to remove undecomposed ammonium salts, the hydrophobic silica aerogel with a density of 0.112 g cm−3reached a mesopore volume of 5.07 cm3g−1and a thermal conductivity of 18.9 mW m−1·K−1. This strategy not only improves the thermal insulation properties, but also offers a significant advancement in tailoring silica aerogels with specific porosity and mesopore volume for various applications.
研究领域:
材料科学
·
隔热材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
TEXTILE RESEARCH JOURNAL
·
2025
·
IF 1.9
Luman Qi,Lingjie Yu,Qiang Zhou,Yuanyuan Lyu,Yongzhen Wang,Yaming Liu,Wei Fan,Jiaguang Meng,Chao Zhi
Polyurethane (PU) foam is widely used in various industries due to its advantages in heat preservation, heat insulation, sound absorption, etc., but this kind of material is extremely flammable and has fire hazards in use. Furthermore, the material compressive properties are insufficient, and the sound absorption performance of medium and low frequencies at low thickness also needs to be improved. Based on the above, in order to comprehensively improve the properties of polyurethane, a ternary layer-stacked composite consisting of spacer fabric/polyurethane/silica aerogel (FPS composite) was innovatively designed and prepared in this study. In the FPS composite, the spacer fabric surface layer functions similarly to the wall mesh fabric, which successfully solves the cracking problem of SiO2 aerogel layer. In addition, the FPS composite reinforced by the spacer fabric with chain + inlay and hexagonal mesh surface structure has compressive modulus of 1.25 MPa and 0.8 MPa, respectively. The thermal conductivity of the two FPS composites is 0.0479 and 0.0452 (W m−1 K−1), respectively, and the FPS composite can achieve flame self-extinguishing within 40 s. In addition, the “filled microperforated plate-like” structure implemented by the introduction of spacer yarns gives the material resonance sound absorption characteristics, the FPS composite has a noise reduction coefficient value of 0.26 at a low thickness of 7.5 mm. To sum up, the composite materials prepared in this study can expand the application field of PU foam and adapt to industries that have requirements for heat preservation, heat insulation, fire prevention, sound absorption, and other aspects.
研究领域:
材料科学
·
防火材料
·
声学工程
✓ 已验证
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2021
·
IF 6.141
Zhiyong Liu,Chuyue Zang,Shu Zhang,Yunsheng Zhang,Zhengcheng Yuan,Huajian Li,Jinyang Jiang
In this paper, silica aerogel is prepared cheaply by atmospheric drying method using coal fired fly ash, a solid waste produced by power generation. By means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), pore size and surface area analysis, X-ray diffraction (XRD), Fourier transform infrared spectrum(FT-IR), laser confocal Raman spectrum(LRS), differential scanning calorimeter(DSC), thermogravimetric analyser(TG) and coefficient of thermal conductivity meter and other modern characterization methods, to explore the surface morphology, microstructure, chemical bond state, thermal stability, chemical stability and thermal conductivity of silica aerogels, and the effect of acid amount on its performance are analyzed. The results show that fly ash can prepare silica aerogel with high purity, high specific surface area, low thermal conductivity, and good chemical stability. When the volume ratio of sulfuric acid to calcining mixture is 10, the silica aerogel prepared has the best performance, the thermal conductivity is as low as 0.0234 W/m·K, the surface is super hydrophobic, the hydrophobic angle can reach 146°, the limit service temperature is 400°C, and the specific surface area is 809.923 m 2 /g.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·
IF 3.5
Mengmeng Yang,Yang Ding,Zhaofeng Chen,Qiong Wu,Lihao Liu,Tianlong Liu,Manna Li,Kai Xu,Lu Le,Lixia Yang
As promising candidates for widespread application, advanced ceramic fiber mats with robust mechanical properties are urgently needed. However, the brittleness, fatigue failure, and large density of ceramic fiber pose significant obstacles to its practical application. Herein, a novel SiO 2 aerogel/ZrO 2 composite nanofibrous membrane (SZCNFM) with excellent flexibility was prepared by introducing SiO 2 aerogel nanoparticles into ZrO 2 nanofiber via simple co-electrospinning. The developed tetragonal zirconia phase without changing up to 1200°C endows SZCNFM material with excellent thermal stability. Furthermore, the as-prepared membranes exhibit fatigue resistance ability which can maintain 98% of the original stress after 100 buckling cycle tests. The addition of mesoporous structure aerogel reduces the heat transfer of the nanofibrous membrane, giving its low thermal conductivity (30 mW/m/K) and low-frequency sound absorption (noise reduction coefficient of 0.52). Combined with the high-temperature resistance, low thermal conductivity and excellent sound-absorption ability make it a promising material for heat insulation and acoustic absorption.
研究领域:
材料科学
·
热学工程
·
声学工程
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Communications
·
2022
·
IF 3.662
Xiaoshan Zhang,Yonggang Jiang,Nana Xu,Haiyan Liu,Nan Wu,Cheng Han,Bing Wang,Yingde Wang
The radome and antenna windows of aerospace aircrafts highly require multifunctional materials that are thermal stable, capable of wave-transparent and have excellent thermal insulation performance. Due to the SiO 2 aerogel with high thermal stability, low dielectric constant and ultralow thermal conductivity , they are considered as promising high-temperature thermal insulating and wave-transparent materials. In this work, the SiBNO fibers with good wave-transparent performance were used as reinforcements to prepare SiO 2 aerogel composites (SiBNO f /SiO 2 ACs) by sol-gel impregnating and supercritical drying method. The prepared SiBNO f /SiO 2 ACs exhibit integrated performances of excellent fire resistance, high-temperature stability (1100 °C in Air), high mechanical properties (compressive strength is 1.89 ± 0.14 MPa at 40 % strain and bending strength is 1.93 ± 0.03 MPa), ultralow thermal conductivity (0.029 W m −1 K −1 at 25 °C and 0.051 W m −1 K −1 at 1100 °C) and good wave-transparent property (dielectric constant<1.45, loss tangent<0.01 in 4–18 GHz). All of these characteristics are related to the unique nanoporous structure of SiO 2 aerogel and intrinsic nature of SiBNO fibers and SiO 2 aerogel. The prepared multifunctional SiBNO f /SiO 2 ACs have great potential to be used in harsh environment for thermal insulation and wave-transparent.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
DOI
高影响因子
JOURNAL OF NON-CRYSTALLINE SOLIDS
·
2018
·
IF 2.488
Ting Zhou,Lunlun Gong,Xudong Cheng,Yuelei Pan,Congcong Li,Heping Zhang
The by-product silicon tetrachloride (SiCl 4 ) was usually obtained from polysilicon industry and was a cheaper alternative precursor. An economic method to produce silica aerogel using silicon tetrachloride under ambient pressure drying was presented in this work, which can also solve the pollution problem during the by-product silicon tetrachloride treatment process. The prepared aerogel samples were characterized by scanning electron microscopy, Brunauer-Emmett-Teller analysis, thermal conductivity analysis, contact angle test, Fourier transform infrared spectroscopy and thermogravimetric analysis . It was found that the molar ratio of H 2 O/SiCl 4 could affect the properties of aerogels seriously. The density and thermal conductivity first decreased and then increased as the molar ratio increased from 13 to 32. The porosity showed an opposite trend with the density. Silica aerogel with high specific surface area (856.7 m 2 /g), low density (0.077 m 3 /g) and low thermal conductivity (0.0213 W/m·k) were obtained at the optimal conditions when the molar ratio was 25. The resulting aerogel is also mesoporous material with super hydrophobicity and have a huge application in thermal insulation field.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）