Dual-porous cellulose nanofibril aerogels via modular drying and cross-linking

Nanoscale ◽  
2020 ◽  
Vol 12 (13) ◽  
pp. 7383-7394 ◽  
Author(s):  
Tingting Wu ◽  
Zhihui Zeng ◽  
Gilberto Siqueira ◽  
Kevin De France ◽  
Deeptanshu Sivaraman ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Supercritical Drying ◽  
Cross Linking ◽  
Cellulose Nanofibril ◽  
Bet Specific Surface Area

Cellulose nanofibril (CNF) dual-porous aerogel with BET specific surface area up to 430 m2 g−1 was prepared via a modular process combining directional freeze-thawing (macro-pores, ca. 50–200 μm) and supercritical drying (meso-pores, ca. 2–50 nm).

Microstructural and porosimetry analysis of Ag-TiO2intercalated kaolin and diatomite as nanocomposite ceramic materials

Clay Minerals ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 665-674 ◽  
Author(s):  
Emmanuel Ajenifuja ◽  
Abimbola P.I. Popoola ◽  
Kabir O. Oyedotun ◽  
Olawale Popoola
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ceramic Materials ◽  
Mineral Particle ◽  
Scanning Calorimetry ◽  
Sintered Ceramic ◽  
Morphological Studies ◽  
Bet Specific Surface Area ◽  
Bet Analysis

ABSTRACTKaolin and diatomite are abundant and widely available geological materials that may immobilize or stabilize functional chemical species on their surfaces for various applications. Acid-treated kaolin and diatomite were intercalated with photocatalyst Ag-TiO2nanoparticles using the sol–gel technique to prepare nanocomposite ceramic materials. The nanocomposites were sintered between 900°C and 1000°C to induce thermal reactions and to enhance nanoparticle–substrate attachment. Chemical and thermal characterizations of the acid-treated materials and intercalated nanocomposites were performed with energy-dispersive X-ray (EDX) analysis and differential scanning calorimetry (DSC), respectively. The Brunauer–Emmett–Teller (BET)-specific surface area and scanning electron microscopy (SEM) were employed for physical and microstructural characterization of the nanocomposites, respectively. Morphological studies revealed a uniform distribution of Ag-TiO2nanocrystallites in pores and on mineral particle surfaces. The BET analysis showed remarkable surface and grain modification by sintering. Decreases in the BET-specific surface area were observed for the sintered ceramic nanocomposite, Ag-TiO2-kaolin (20.244 to 5.446 m2/g) and Ag-TiO2-diatomite (19.582 to 10.148 m2/g).

scholarly journals Activated Carbons from Thermoplastic Precursors and Their Energy Storage Applications

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 896 ◽  
Author(s):  
Hye-Min Lee ◽  
Kwan-Woo Kim ◽  
Young-Kwon Park ◽  
Kay-Hyeok An ◽  
Soo-Jin Park ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Specific Surface ◽  
Surface Area ◽  
Field Emission ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Cross Linking ◽  
Mesopore Volume

In this study, low-density polyethylene (LDPE)-derived activated carbons (PE-AC) were prepared as electrode materials for an electric double-layer capacitor (EDLC) by techniques of cross-linking, carbonization, and subsequent activation under various conditions. The surface morphologies and structural characteristics of the PE-AC were observed by field-emission scanning electron microscope, Cs-corrected field-emission transmission electron microscope, and X-ray diffraction analysis, respectively. The nitrogen adsorption isotherm-desorption characteristics were confirmed by Brunauer–Emmett–Teller, nonlocal density functional theory, and Barrett–Joyner–Halenda equations at 77 K. The results showed that the specific surface area and total pore volume of the activated samples increased with increasing the activation time. The specific surface area, the total pore volume, and mesopore volume of the PE-AC were found to be increased finally to 1600 m2/g, 0.86 cm3/g, and 0.3 cm3/g, respectively. The PE-AC also exhibited a high mesopore volume ratio of 35%. This mesopore-rich characteristic of the activated carbon from the LDPE is considered to be originated from the cross-linking density and crystallinity of precursor polymer. The high specific surface area and mesopore volume of the PE-AC led to their excellent performance as EDLC electrodes, including a specific capacitance of 112 F/g.

N2-BET specific surface area of bentonites

2010 ◽  
Vol 349 (1) ◽  
pp. 275-282 ◽  
Author(s):  
S. Kaufhold ◽  
R. Dohrmann ◽  
M. Klinkenberg ◽  
S. Siegesmund ◽  
K. Ufer
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Bet Specific Surface Area

Alumina aerogel catalysts prepared by two supercritical drying methods used in methane combustion

1995 ◽  
Vol 10 (6) ◽  
pp. 1424-1428 ◽  
Author(s):  
Yasuyuki Mizushima ◽  
Makoto Hori
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Methane Combustion ◽  
Supercritical Drying ◽  
High Specific Surface Area ◽  
The Other ◽  
Drying Methods ◽  
Alumina Aerogel ◽  
Lower Temperature

Palladium-supported alumina aerogels were prepared by two different supercritical drying methods. In one method, an alumina wet gel was dried under supercritical conditions of ethanol in an autoclave. In the other, the aerogel was supercritically dried by extracting ethanol using carbon dioxide in an extractor. The Pd-supported alumina aerogel prepared in the autoclave exhibited a high specific surface area of 112.8 m2/g after firing at 1200 °C for 5 h, while the other had a specific surface area of only 5.2 m2/g due to α-alumina transformation. Their catalytic properties for methane combustion were measured. The Pd-supported alumina aerogel prepared in the autoclave combusts methane perfectly at 50–60 °C lower temperature than the other. Palladium particles on the alumina aerogel prepared in the autoclave contained palladium oxide, while those prepared in the CO2 extractor contained only palladium metal.

Synthesis of Mesoporous Zr-P-Al Materials with High BET Specific Surface Area without Calcination

2011 ◽  
Vol 287-290 ◽  
pp. 2094-2101
Author(s):  
Zi Yu Liu ◽  
Yue Qi ◽  
Ying Xu Wei ◽  
Zong Bin Wu ◽  
Zhong Min Liu
Keyword(s):  
Phosphoric Acid ◽  
Specific Surface ◽  
Surface Area ◽  
Long Range ◽  
Specific Surface Area ◽  
Acid Concentration ◽  
Long Range Order ◽  
Bet Specific Surface Area ◽  
Textual Data ◽  
Phosphoric Acid Concentration

A mesostructured zirconium oxide was synthesized hydrothermally using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent and ZrSO4. 4H2O as the reactant. Subsequent post-synthetic treatment with H3PO4followed by the treatment with AlCl3solutions resulted in mesoporous Zr-P-Al materials, which exhibited high BET specific surface area before calcination. The phosphoric acid concentrationaffected the textual data of the resulting Zr-P and Zr-P-Al materials greatly. 0.1-0.5 M H3PO4increased obviously the long-range order of the as-synthesized Zr-P materials while 0.76 M H3PO4decreased it. After calcination at 773 K, the Zr-P materials turned to nonporous materials except the one synthesized by 0.5 M H3PO4, which showed micropores with a BET specific surface area of 147 m2/g. Further treating the Zr-P materials (synthesized from different concentration of phosphoric acid) with the same amount of AlCl3solution resulted in mesoporous Zr-P-Al materials, but the long-range order of which decreased when the H3PO4concentration increased. Similarly, the BET specific surface area of the above-mentioned Zr-P-Al materials decreased from 462 m2/g for 0.25 M H3PO4to 394 m2/g for 0.5 M H3PO4and finally to 332 m2/g for 0.76 M H3PO4after calcination at 773 K, while the pore size increased gradually from 3.0 to 3.5 nm. It was found that about 90% of the CTAB had been removed during the AlCl3treatment and that the as-synthesized Zr-P-Al materials exhibited high BET specific surface area as well as mesopores. The AlCl3amount is another factor affecting the textual data of the uncalcined Zr-P-Al materials besides the H3PO4concentration. With the phosphoric acid concentration of 0.25 M, the BET specific surface area of the as-synthesized Zr-P-Al materials increased from 477 m2/g to as high as 734 m2/g with the increasing AlCl3amount before it decreased from then on.

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