Preparation and Characterization of Aerogel-Based Carbon Nanocomposites

1994 ◽  
Vol 349 ◽  
Author(s):  
Wanqing Cao ◽  
Xian Yun Song ◽  
Arlon J. Hunt
Keyword(s):  
Elevated Temperatures ◽  
High Surface ◽  
Sol Gel ◽  
Average Particle Size ◽  
High Surface Area ◽  
Porous Solids ◽  
Average Particle ◽  
Infrared Transmission ◽  
Hydrocarbon Gases ◽  
Original Weight

ABSTRACTAerogels are highly porous solids prepared by sol-gel processing and supercritical evacuation. Because of their high surface area, aerogels can be used as an effective catalyst for the thermal decomposition of many gaseous compounds. A variety of hydrocarbon gases have been chosen to deposit carbon in the aerogel matrix, with the deposition temperature varying from 500° to 850°C depending on the hydrocarbon used. The amount of carbon that can be deposited in the aerogel is surprisingly large, reaching up to 10 times the original weight after extensive deposition using acetylene. Overall, the aerogel composites prepared have a uniform microstructure with the average particle size in the nanometer range. In addition, we have observed some interesting graphitic structures including carbon nanotubes and rings of various shapes. Carbon deposited in the aerogel can reduce infrared transmission of the material as well as volume shrinkage at elevated temperatures, thereby improving its thermal performance.

Effects of Preparation Conditions on Characters of Hydrophobic Silica Granular Aerogel and its Applications

2012 ◽  
Vol 600 ◽  
pp. 190-193 ◽  
Author(s):  
Wei Wei ◽  
Jing Yi Zhang ◽  
Li Ping Wu ◽  
Guo Tong Qin
Keyword(s):  
Particle Size ◽  
Ambient Pressure ◽  
High Surface ◽  
Sol Gel ◽  
Average Particle Size ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Ambient Pressure Drying ◽  
Average Particle ◽  
Hydrophobic Silica

The hydrophobic silica granular aerogels were synthesized via sol-gel synthesis followed by ambient pressure drying. The tetraethyloxylane (TEOS) was used as original precursor. The aerogels were analyzed using nitrogen adsorption, scanning electron microscopy (SEM) and laser particle size analyzer. It was found that the aerogel was mesoporous material with high surface area. The aerogels were prepared in grain form by dipping into disperse solution in order to adsorption application. The average particle size of the aerogel was controlled by pH and disperse solution volume. The pH also affected gel time. The aerogels were used to absorb phenol from water. The saturated adsorption amount could reach up to 145 mg•g-1.

scholarly journals Fabrication and characterisation of Fe2O3/chitosan aerogel-like spheres

2021 ◽  
Vol 10 (1) ◽  
pp. 74-78
Author(s):  
Nhan Dang Thi Thanh ◽  
Don Truong Thi ◽  
Thang Le Quoc ◽  
Tien Tran Dong ◽  
Son Le Lam
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
Average Particle Size ◽  
High Surface Area ◽  
Hollow Structure ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Factors Affecting ◽  
Sol Gel Process ◽  
High Surface Area Materials

Presently, biopolymer materials have been given more attention for their outstanding properties, high efficiencies and promising applications in various fields. In this study, Fe2O3/chitosan aerogel-like spheres were successfully prepared from chitosan and FeCl3 by sol–gel process and freeze-drying to provide high-surface area materials. The factors affecting the material synthesis have been studied. The asprepared Fe2O3/chitosan material was characterized by Infrared Spectroscopy (IR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) methods. The results showed that the aerogel spheres have a hollow structure made of chitosan nanofibril networks. Fe2O3 nanoparticles get high crystallinity and have an average particle size of 33 nm.

Porous Solids of Boron Phosphate, Aluminum Phosphate, and Silicon Phosphate

1994 ◽  
Vol 371 ◽  
Author(s):  
K. B. Babb ◽  
D. A. Lindquist ◽  
S. S. Rooke ◽  
W. E. Young ◽  
M. G. Kleve
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Total Pore Volume ◽  
Aluminum Phosphate ◽  
Porous Solids ◽  
Gel Point ◽  
Average Pore ◽  
Average Pore Radius ◽  
Surface Areas

AbstractAnhydrous sol-gel condensation of triethyl phosphate [(CH3CH2O)3PO] with boron trichioride (BCl3), triethyl aluminum [(CH3CH2)3Al] or silicon tetrachloride [SiCI4] in organic solvents led to rigid gels. The pore fluid of the gels was removed under supercritical conditions in a pressurized vessel to form porous solids. The condensation chemistry prior to the gel point was monitored by solution 1H, 13C, 31P, and 11B NMR. The materials were then calcined at progressively higher temperatures to produce high surface area phosphates. Nitrogen gasphysisorption was used to determine the surface areas, total pore volume, and average pore radius of the products. FT-IR was used to determine functional groups in the materials. The microstructure was also examined by scanning electron microscopy.

Comparison of nickel oxide and palladium nanoparticle loaded on activated carbon for efficient removal of methylene blue

2014 ◽  
Vol 34 (2) ◽  
pp. 153-169 ◽  
Author(s):  
S Arabzadeh ◽  
M Ghaedi ◽  
A Ansari ◽  
F Taghizadeh ◽  
M Rajabi
Keyword(s):  
Electron Microscopy ◽  
Methylene Blue ◽  
Particle Size ◽  
Activated Carbon ◽  
Nickel Oxide ◽  
High Surface ◽  
Average Particle Size ◽  
High Surface Area ◽  
Average Particle ◽  
Efficient Removal

Palladium nanoparticles (Pd-NPs) and nickel oxide nanoparticles (NiO-NPs) were synthesized and loaded on activated carbon (AC). This novel material successfully used for the removal of methylene blue (MB) dye from aqueous medium. Full characterization of both material using X-ray diffraction, transmission electron microscopy, scanning electron microscopy and Brunauer–Emmet–Teller analyses for Pd-NP show their high surface area (>1340 m2/g) and low pore size (<20 Å) and average particle size lower than 45 Å and for NiO-NP show their high surface area (>1316.1554 m2/g) and low pore size (<20 Å) and average particle size lower than 46 Å in addition to high reactive atom and presence of various functional groups. These unique properties make them possible for efficient removal of MB. In batch experimental set-up, optimum conditions for maximum removal of MB by both adsorbents were attained following searching effect of variables such as central composite design. The Langmuir isotherm was found to be highly recommended for fitting the experimental equilibrium data. The kinetic of adsorption of MB on both adsorbents strongly can be fitted by a combination of pseudo-second order and intraparticle diffusion pathway. The experimental result achieved in this article shows the superiority of Pd-NP-AC for MB removal than NiO-NP-AC, so the maximum adsorption capacities of Pd-NP-AC and NiO-NP-AC were 555.5 mg/g and 588.2 mg/g, respectively.

SYNTHESIS OF MESOPOROUS IRON OXIDE NANOPARTICLES FROM MESOPOROUS SILICA TEMPLATE VIA NANO-REPLICATION

2008 ◽  
Vol 01 (02) ◽  
pp. 151-154 ◽  
Author(s):  
JEONG KUK SHON ◽  
SOO SUNG KONG ◽  
SUNG SOO KIM ◽  
MIN SUK KANG ◽  
JI MAN KIM ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Mesoporous Silica ◽  
High Surface ◽  
Average Particle Size ◽  
High Surface Area ◽  
Spherical Shape ◽  
Average Particle ◽  
Replication Method ◽  
Ordered Mesoporous ◽  
Silica Template

Highly ordered mesoporous iron oxide (α- Fe 2 O 3) material has been successfully obtained from mesoporous silica template, KIT-6 (3-D Cubic Ia3d symmetry), through nano-replication method. The mesoporous α- Fe 2 O 3 material thus obtained exhibits well-defined mesopores (2.7 nm in diameter), high surface area (148 m2/g), high pore volume (0.47 cm3/g) and crystalline frameworks. The morphology of the mesoporous α- Fe 2 O 3 material is very uniform in spherical shape of which the average particle size is about 100 nm in diameter.

scholarly journals PEG Coated Fe3O4/RGO Nano-Cube-Like Structures for Cancer Therapy via Magnetic Hyperthermia

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2398
Author(s):  
Anoud Alkhayal ◽  
Arshia Fathima ◽  
Ali H. Alhasan ◽  
Edreese H. Alsharaeh
Keyword(s):  
Time Pressure ◽  
High Surface ◽  
Average Particle Size ◽  
High Surface Area ◽  
Volume Ratio ◽  
Superparamagnetic Iron Oxide ◽  
Magnetic Hyperthermia ◽  
Average Particle ◽  
Microwave Hydrothermal ◽  
Poly Ethylene

Superparamagnetic iron oxide nanoparticles (SPIONs) have high saturation magnetization and are promising candidates for hyperthermia. They may act as magnetic heating agents when subjected to magnetic field in nano-based hyperthermia. In this work, cube-like Fe3O4 nanoparticles (labelled as cubic SPIONs) with reduced graphene oxide (RGO) nanocomposites were prepared by a microwave hydrothermal method. The shape and size of magnetic nanoparticles were controlled by varying synthesis parameters, including reaction time, pressure and microwave power. This study successfully synthesized cubic SPIONs nanocomposites with an average particle size between 24–34 nm. Poly-(ethylene) glycol (PEG) was used as a coating material on SPIONs to enhance biocompatibility. The RGO sheets provided a high surface area-to-volume ratio for SPIONs to be dispersed on their surface, and hence, they prevented aggregation of the SPIONs in the nanocomposites. Magnetically induced heating studies on the optimized nanocomposite (Fe3O4/RGO/PEG) demonstrated heating capabilities for magnetic hyperthermia application with a promising specific absorption rate (SAR) value of 58.33 W/g in acidic solution. Cytotoxicity tests were also performed to ensure low nanoparticle toxicity before incorporation into the human body. The results of the standard assay for the toxicity determination of the nanocomposites revealed over 70% cell survival after 48 h, suggesting the feasibility of using the synthesized nanocomposites for magnetic hyperthermia.

Inorganic and Organic Aerogels

MRS Bulletin ◽  
1990 ◽  
Vol 15 (12) ◽  
pp. 30-36
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Visible Spectrum ◽  
Supercritical Drying ◽  
Porous Solids ◽  
Metal Alkoxides ◽  
Open Cell Foams ◽  
Sol Gel Transition ◽  
Organic Aerogels

Aerogels are a special class of open-cell foams derived from the supercritical drying of highly cross-linked inorganic or organic gels. These materials have ultrafine cell/pore sizes (less than 1,000 Å), continuous porosity, high surface area (400–1000 m2/g), and a microstructure composed of interconnected colloidal-like particles or polymeric chains with characteristic diameters of 100 Å. This microstructure is responsible for the unusual optical, acoustic, thermal, and mechanical properties of aerogels. For example, aerogels can be prepared as transparent, porous solids because their ultrafine cell/pore size minimizes light scattering in the visible spectrum. Figure 4.1 shows the different aerogels that will be discussed in this article.The hydrolysis and condensation of metal alkoxides is the most common synthetic route for the formation of inorganic aerogels. Inorganic aerogels have been prepared from monomers such as tetraisopropoxy titanate, aluminum secbutylate, and zirconium isopropoxide. Nevertheless, the majority of scientific research has concentrated on the sol-gel polymerization of tetramethoxysilane (TMOS), or the less toxic tetraethoxysilane (TEOS). The resultant silica aerogels are being investigated for applications ranging from window insulation to the collection of hypervelocity partis cles in space.The sol-gel polymerization of a multifunctional monomer in solution, leading to the formation of an aerogel, is not unique to metal alkoxides. Organic reactions that proceed through a sol-gel transition have been discovered recently.

scholarly journals High surface area nano-sized La0.6Ca0.4MnO3 perovskite powder prepared by low temperature pyrolysis of a modified citrate gel

2009 ◽  
Vol 7 (4) ◽  
pp. 809-817 ◽  
Author(s):  
Meysam Soleymani ◽  
Ahmad Moheb ◽  
Ezatolah Joudaki
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Single Phase ◽  
High Surface ◽  
Average Particle Size ◽  
High Surface Area ◽  
Average Particle ◽  
Precursor Method ◽  
Modified Method ◽  
Low Temperature Pyrolysis

AbstractSingle phase nanocrystalline La0.6Ca0.4MnO3 powder was synthesized by both the usual and a modified citrate gel precursor method, and the effects on the formation of homogeneous nano-sized powder with a perovskite structure were investigated. In the modified method, single phase La0.6Ca0.4MnO3 powder with an average particle size of 17.2 nm was obtained when the powder was pyrolyzed at 520°C for 2 h. Its specific surface area was 40.7 m2 g−1, about 4-fold larger than that of powder made by the usual citrate gel method.

scholarly journals Photocatalytic Decolorization of Methyl Red on Nanoporous Anodic ZrO2 of Different Crystal Structures

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 215
Author(s):  
Ewa Wierzbicka ◽  
Karolina Syrek ◽  
Klaudia Mączka ◽  
Grzegorz D. Sulka
Keyword(s):  
Photocatalytic Activity ◽  
Photocatalytic Performance ◽  
Elevated Temperatures ◽  
Aqueous Electrolyte ◽  
High Surface ◽  
High Surface Area ◽  
Methyl Red ◽  
Self Organized ◽  
Photocatalytic Decolorization ◽  
Perfect Adhesion

High surface area, self-organized nanoporous ZrO2 arrays with perfect adhesion to the Zr substrate were synthesized by anodization in an aqueous electrolyte containing (NH4)2SO4 and NH4F. The obtained semiconductor materials were tested as photocatalysts for decolorization of the methyl red (MR) as a model azo dye pollutant. It was demonstrated that as-synthesized anodic ZrO2 anodic layers are already crystalline and, therefore, do not require further thermal treatment to provide a high photocatalytic performance. However, photocatalytic efficiency could be improved by annealing at a relatively low-temperature of 350 °C. Higher annealing temperatures caused a gradual drop of photocatalytic activity. The photocatalytic behavior was correlated with the crystal phase transformation in anodic ZrO2. It was found that higher photocatalytic activity was observed for the tetragonal phase over the monoclinic phase (predominant at elevated temperatures). It results from the optimal and complex electronic structure of annealed ZrO2 with three different energy states having absorption edges at 2.0, 4.01 and 5.28 eV.

High-Surface-Area Alumina-Silica Nanocatalysts Prepared by a Hybrid Sol-Gel Route Using a Boehmite Precursor

2010 ◽  
Vol 93 (12) ◽  
pp. 4047-4052 ◽  
Author(s):  
Padmaja Parameswaran Nampi ◽  
Padmanabhan Moothetty ◽  
Wilfried Wunderlich ◽  
Frank John Berry ◽  
Michael Mortimer ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area
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