Investigation of microstructure and mechanical properties of novolac/silica and C/SiO2/SiC aerogels using mercury porosimetry method

Seraji, Mohamad Mehdi; Ghafoorian, Nafiseh Sadat; Bahramian, Ahmad Reza

doi:10.1016/j.jnoncrysol.2015.12.021

Cited by 26 publications

(5 citation statements)

References 25 publications

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“…This increase in surface areas can be related to the formation of new micro pores, due to Novolac particles present in OX texture can decompose into volatile gases in heat treatment. In fact when these volatile gases leave the xerogel structure, new voids are generated in the xerogel composite structure [23]. Also, explosive property of NH 4 Cl in high temperature causes developing new micro pores in the texture of CX [19].…”

Section: Characterization Resultsmentioning

confidence: 99%

Use of NH4Cl for activation of carbon xerogel to prepare a novel efficacious adsorbent for benzene removal from contaminated air streams in a fixed-bed column

Rastegar

Gholami

Jafari

et al. 2020

J Environ Health Sci Engineer

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Background Ammonium chloride as an explosive salt has proved to be a prominent activation agent for adsorbents and increase the specific surface area and volume of cavities. In this work, the ability of this substance was scrutinized for activation of carbon aerogel to prepare an efficient adsorbent for benzene removal from air streams. Methods A carbon xerogel was fabricated from Novallac polymer and activated by ammonium chloride.The changes in structure and morphology were considered via Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Barrett-Joyner-Halenda (BJH), and energy dispersive X-ray (EDX) analyses. Also, comprehensive studies were conducted to vouchsafe the properties of the new adsorbent for benzene removal, using a fixed-bed column mode. Results The results showed both the successful synthesis and the suitability of the activation process. ACX possessed a higher specific surface area (1008 g/m3), compared to the parent carbon xerogel (CX; 543.7 g/m3) and organic xerogel (OX; 47 g/m3), as well as a higher adsorption capacity. Conclusion NH4CL is a very beneficial for modifying the structure and morphology of carbon aerogel, and the dynamic behavior of the column with respect inlet benzene concentration can be explained by Yan-Nelson model.

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Section: Characterization Resultsmentioning

confidence: 99%

Use of NH4Cl for activation of carbon xerogel to prepare a novel efficacious adsorbent for benzene removal from contaminated air streams in a fixed-bed column

Rastegar

Gholami

Jafari

et al. 2020

J Environ Health Sci Engineer

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“…For aerogel A1, P 1 is about 5 MPa, which is much higher than those of A2 and A3. Then, we apply the Washburn equation (eq ) to each aerogel at P c as follows: − where r refers to radius of the cylindrical pore, γ refers to the surface tension of mercury, P refers to the pressure at which mercury penetrates into the pore, and θ refers to the contact angle between the mercury meniscus and a flat nonmetallic surface. For each P c , aerogel prepared without acid (aerogel A1) has the minimum r .…”

Section: Resultsmentioning

confidence: 99%

Vacuum-Dried Synthesis of Low-Density Hydrophobic Monolithic Bridged Silsesquioxane Aerogels for Oil/Water Separation: Effects of Acid Catalyst and Its Excellent Flexibility

Chen

Gao

Jin

et al. 2018

ACS Appl. Nano Mater.

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Low-density hydrophobic monolithic bridged silsesquioxane aerogels were prepared by vacuum drying using terephthalaldehyde (TPAL) and 3-aminopropyl-triethoxysilane (APTES) as precursors and acetic acid as catalyst. The effects of acid on the vacuum-dried synthesis of bridged silsesquioxane aerogels were investigated. The results indicate that the growth mechanism changes from cluster−cluster to monomer−cluster when acid is added, which induces the formation of the low-density monolithic aerogels with increased pore size. The methyltrimethoxysilane (MTMS) co-precursor could endow the aerogels with good hydrophobicity. The densities, pore structure, hydrophobicity, and mechanical properties of the obtained bridged silsesquioxane aerogels were investigated in detail. The results show that the monolithic aerogels possess low density (0.071 g/cm 3 ), high hydrophobicity (contact angle, >140°), and excellent flexibility (Young's modulus, 0.029 MPa). All of these characteristics make the hydrophobic aerogels competitive candidates for oil/water separation.

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“…Regardless, the pore size distribution can also be verified by SEM images. The nitrogen adsorption method and mercury injection method have also been widely used to evaluate the multiscale pore size distribution of aerogel materials [ 31 , 32 , 33 , 34 ].…”

Section: Resultsmentioning

confidence: 99%

Experimental Characterization of the Thermal Conductivity and Microstructure of Opacifier-Fiber-Aerogel Composite

Zhang

et al. 2018

Molecules

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Due to their high-porosity, nanoporous structure and pores, aerogel materials possess extremely low thermal conductivity and have broad potential in the thermal insulation field. Silica aerogel materials are widely used because of their low thermal conductivity and high temperature resistance. Pure silica aerogel is very fragile and nearly transparent to the infrared spectrum within 3–8 μm. Doping fibers and opacifiers can overcome these drawbacks. In this paper, the influences of opacifier type and content on the thermal conductivity of silica fiber mat-aerogel composite are experimentally studied using the transient plane source method. The thermal insulation performances are compared from 100 to 750 °C at constant pressure in nitrogen atmosphere among pure fiber mat, fiber mat-aerogel, 20% SiC-fiber mat-aerogel, 30% ZrO2-fiber mat-aerogel and 20% SiC + 30% ZrO2-fiber mat-aerogel. Fiber mat-aerogel doped with 20% SiC has the lowest thermal conductivity, 0.0792 W/m·K at 750 °C, which proves that the proper type and moderate content of opacifier dominates the low thermal conductivity. The pore size distribution indicates that the volume fraction of the micropore and mesopore is also the key factor for reducing the thermal conductivity of porous materials.

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Investigation of microstructure and mechanical properties of novolac/silica and C/SiO2/SiC aerogels using mercury porosimetry method

Cited by 26 publications

References 25 publications

Use of NH4Cl for activation of carbon xerogel to prepare a novel efficacious adsorbent for benzene removal from contaminated air streams in a fixed-bed column

Use of NH4Cl for activation of carbon xerogel to prepare a novel efficacious adsorbent for benzene removal from contaminated air streams in a fixed-bed column

Vacuum-Dried Synthesis of Low-Density Hydrophobic Monolithic Bridged Silsesquioxane Aerogels for Oil/Water Separation: Effects of Acid Catalyst and Its Excellent Flexibility

Experimental Characterization of the Thermal Conductivity and Microstructure of Opacifier-Fiber-Aerogel Composite

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