Improved Synthesis of Nanosized Silica in Water-in-Oil Microemulsions

Present contribution describes modified Stöber synthesis of silica nanoparticles in oil-in-water microemulsion, formulated using heptane, 2-ethylhexanol, Tween® 85 nonionic surfactant, and tetraethyl orthosilicate (TEOS). After some specified incubation time, ammonium hydroxide was added and the reaction mixture was stirred for 24 hours at room temperature. Prior to synthesis, pseudoternary diagram was created for oil-rich area and Winsor IV region was identified. These microemulsions were used for synthesis of silica particles. Resulting particles were characterized by dynamic light scattering, electrokinetic measurements, specific surface area measurements, and powder diffraction. Particles’ diameter was ranging between ca. 130 and 500 nm; usually monodisperse distribution was obtained. The specific surface area of nanoparticles was ranging between 250 and 300 m2/g. Notably, productivity per unit volume of solution was 3 to 5 times higher than for previously reported procedures. Our method can be extended, because polymeric materials can be added to dispersed aqueous phase. In our studies, β-cyclodextrin and hydroxyethylcellulose have been used, giving particles between 170 and 422 nm, with the surface area larger than 300 m2/g.

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Preparation and Application of 2D MXene-Based Gas Sensors: A Review

Chemosensors ◽

10.3390/chemosensors9080225 ◽

2021 ◽

Vol 9 (8) ◽

pp. 225

Author(s):

Qingting Li ◽

Yanqiong Li ◽

Wen Zeng

Keyword(s):

Composite Materials ◽

Specific Surface ◽

Surface Area ◽

Gas Sensor ◽

Specific Surface Area ◽

Gas Sensors ◽

Room Temperature ◽

Gas Sensing ◽

Interlayer Spacing ◽

Preparation Methods

Since MXene (a two-dimensional material) was discovered in 2011, it has been favored in all aspects due to its rich surface functional groups, large specific surface area, high conductivity, large porosity, rich organic bonds, and high hydrophilicity. In this paper, the preparation of MXene is introduced first. HF etching was the first etching method for MXene; however, HF is corrosive, resulting in the development of the in situ HF method (fluoride + HCl). Due to the harmful effects of fluorine terminal on the performance of MXene, a fluorine-free preparation method was developed. The increase in interlayer spacing brought about by adding an intercalator can affect MXene’s performance. The usual preparation methods render MXene inevitably agglomerate and the resulting yields are insufficient. Many new preparation methods were researched in order to solve the problems of agglomeration and yield. Secondly, the application of MXene-based materials in gas sensors was discussed. MXene is often regarded as a flexible gas sensor, and the detection of ppb-level acetone at room temperature was observed for the first time. After the formation of composite materials, the increasing interlayer spacing and the specific surface area increased the number of active sites of gas adsorption and the gas sensitivity performance improved. Moreover, this paper discusses the gas-sensing mechanism of MXene. The gas-sensing mechanism of metallic MXene is affected by the expansion of the lamellae and will be doped with H2O and oxygen during the etching process in order to become a p-type semiconductor. A p-n heterojunction and a Schottky barrier forms due to combinations with other semiconductors; thus, the gas sensitivities of composite materials are regulated and controlled by them. Although there are only several reports on the application of MXene materials to gas sensors, MXene and its composite materials are expected to become materials that can effectively detect gases at room temperature, especially for the detection of NH3 and VOC gas. Finally, the challenges and opportunities of MXene as a gas sensor are discussed.

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New Production Route of Magnesium Hydroxide and Related Environmental Impact

Sustainability ◽

10.3390/su12218822 ◽

2020 ◽

Vol 12 (21) ◽

pp. 8822

Author(s):

Andrzej Jarosinski ◽

Piotr Radomski ◽

Lukasz Lelek ◽

Joanna Kulczycka

Keyword(s):

Environmental Impact ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Magnesium Hydroxide ◽

Flame Retardants ◽

Polymeric Materials ◽

New Production ◽

Constant Flow Rate ◽

The Impact

The paper presents research on a method of obtaining magnesium hydroxide from magnesium sulphate salts and NaOH. In order to acquire the desired and controlled properties, the method of precipitating in aqueous solutions by introducing a NaOH solution into a solution of MgSO4 has been applied. To get as stable a product as possible with graining, the introduction of NaOH takes place at a constant flow rate. In order to identify the environmental impact of the developed process, a life cycle assessment (LCA) has been made. The use of the proposed method for the synthesis of Mg(OH)2 incorporating washing with 25% ammonia solution and acetone enabled a product with a high specific surface area. The Mg(OH)2 obtained was characterised by a higher specific surface area than commercially available magnesium hydroxides that are used as additives for flame retardants in polymeric materials. This allows the material to be used as an anti-pyrogen for a wider group of polymeric materials. For the LCA analysis, two scenarios were assumed, from which the basic one included recovery of ammonia and acetone. The environmental analysis carried out confirmed the validity of this assumption, as it was stated that the main part of the impact was connected with the supply chain for the process examined.

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Nano-Sized Fe(III) Oxide Particles Starting from an Innovative and Eco-Friendly Synthesis Method

Nanomaterials ◽

10.3390/nano10020323 ◽

2020 ◽

Vol 10 (2) ◽

pp. 323 ◽

Cited By ~ 3

Author(s):

Ludovico Macera ◽

Giuliana Taglieri ◽

Valeria Daniele ◽

Maurizio Passacantando ◽

Franco D’Orazio

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Photoelectron Spectroscopy ◽

Room Temperature ◽

Magnetic Measurements ◽

Ambient Pressure ◽

Synthesis Method ◽

Hematite Nanoparticles ◽

X Ray

This paper introduces an original, eco-friendly and scalable method to synthesize ferrihydrite nanoparticles in aqueous suspensions, which can also be used as a precursor to produce α-hematite nanoparticles. The method, never used before to synthesize iron oxides, is based on an ion exchange process allowing to operate in one-step, with reduced times, at room temperature and ambient pressure, and using cheap or renewable reagents. The influence of reagent concentrations and time of the process on the ferrihydrite features is considered. The transformation to hematite is then analyzed and discussed in relation to different procedures: (1) A natural aging in the water at room temperature; and (2) heat treatments at different temperatures and times. Structural and morphological features of the obtained nanoparticles are investigated by means of several techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, thermal analysis, nitrogen adsorption and magnetic measurements. Ferrihydrite shows the typical spherical morphology and a very high specific surface area of 420 m2/g. Rhombohedral or plate-like hexagonal hematite nanoparticles are obtained by the two procedures, characterized by dimensions of 50 nm and 30 nm, respectively, and a specific surface area up to 57 m2/g, which is among the highest values reported in the literature for hematite NPs.

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Restricted Dynamics in Polymer-Filler Systems

MRS Proceedings ◽

10.1557/proc-661-kk4.4 ◽

2000 ◽

Vol 661 ◽

Author(s):

V. Arrighi ◽

S. Gagliardi ◽

Julia S. Higgins

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Dynamic Properties ◽

Polymeric Materials ◽

Weight Fraction ◽

Average Diameter ◽

Hydrogen Atoms ◽

Polymer Filler ◽

Wide Range

ABSTRACTComposites in which fibres or fillers are incorporated into a polymeric component exhibit improved mechanical strength compared to the polymer matrix. This reinforcement effect strongly depends on the properties of the interphase and the specific interactions between the polymer and the reinforcing additive.A wide range of experimental methods have been used to assess the effect of active fillers on the mobility of the polymer chains. The experimental results from NMR, dielectric spectroscopy and dynamical thermal analysis reveal that the mobility of chain units adjacent to the adsorbed surface differs considerably from the bulk.We have used quasielastic neutron scattering to investigate the dynamic properties of poly(dimethyl siloxane) (PDMS) filled with silica particles. This technique which probes the motion of the hydrogen atoms has been extensively used to study the local dynamics of polymeric materials. In this paper we show that QENS provides detailed information on the reduced mobility of chain segments in polymer-filler systems.QENS measurements were carried out on PDMS filled with hydrophilic Aerosil with different specific surface area (average diameter 7 and 20 nm). Detailed data analysis indicates that the QENS spectra of the polymer-filler composites can be described by the sum of two contributions: (a) a quasielastic component due to chains not affected by the presence of the fillers and (b) an elastic term from those chain segments strongly affected by the presence of fillers. The latter depends on the specific surface area of the particles and their weight fraction in the composite.

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P–p heterojunction CuO/CuCo2O4 nanotubes synthesized via electrospinning technology for detecting n-propanol gas at room temperature

Inorganic Chemistry Frontiers ◽

10.1039/c7qi00192d ◽

2017 ◽

Vol 4 (7) ◽

pp. 1219-1230 ◽

Cited By ~ 27

Author(s):

Khaled Tawfik Alali ◽

Zetong Lu ◽

Hongsen Zhang ◽

Jingyuan Liu ◽

Qi Liu ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Room Temperature ◽

Gas Sensing ◽

Tubular Structure ◽

Large Specific Surface Area ◽

Sensing Performance

Composite CuO/CuCo2O4 nanotubes were synthesized by electrospinning technology. The large specific surface area, complex tubular structure, and p–p heterojunction are the potential reasons for the excellent room temperature gas sensing performance toward n-propanol vapor.

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Synthesis and Structural Characterization of Ti2C Nanosheets

Materials Science Forum ◽

10.4028/www.scientific.net/msf.833.44 ◽

2015 ◽

Vol 833 ◽

pp. 44-47 ◽

Cited By ~ 2

Author(s):

Jing Xiao Li ◽

Yu Lei Du ◽

Chong Cui

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Structural Characterization ◽

Room Temperature ◽

Atomic Composition ◽

Two Dimensional

In this paper, two-dimensional (2D) Ti2C nanosheets were synthesized by exfoliation of Ti2AlC powders in HF solution at room temperature. The surface atomic composition and chemistry of as-prepared Ti2C nanosheets were studied by XPS. The specific surface area of Ti2C nanosheets were determined by BET. The as-prepared Ti2C nanosheets are stacked and held together, which leads to the lower specific surface area of the as-prepared Ti2C nanosheets.

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Mechanochemical-hydrothermal preparation of crystalline hydroxyapatite powders at room temperature

Journal of Materials Research ◽

10.1557/jmr.2001.0170 ◽

2001 ◽

Vol 16 (5) ◽

pp. 1231-1234 ◽

Cited By ~ 41

Author(s):

Pavel Shuk ◽

Wojciech L. Suchanek ◽

Tian Hao ◽

Eric Gulliver ◽

Richard E. Riman ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Room Temperature ◽

Heterogeneous Reaction ◽

Stoichiometric Composition ◽

X Ray Diffraction ◽

Hydrothermal Preparation ◽

Hydrothermal Route ◽

20 Nm

Crystalline hydroxyapatite (HAp) powders were prepared at room temperature from heterogeneous reaction between Ca(OH)2powders and (NH4)2HPO4 solutions via the mechanochemical-hydrothermal route. X-ray diffraction, infrared spectroscopy, thermogravimetric characterization, and chemical analysis were performed, and it was determined that the room temperature products were phase-pure, thermally stable HAp with a nearly stoichiometric composition. Dynamic light scattering revealed that the dispersed particle size distribution of the room temperature HAp powders was in the range of 0.15–3.0 μm with a specific surface area of ≈90 m2/g. Both specific surface area measurements and scanning electron microscopy confirmed that the HAp powders consisted of agglomerates containing hundreds of ≈20 nm HAp crystals.

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Silver nanocrystal-decorated polyoxometalate single-walled nanotubes as nanoreactors for desulfurization catalysis at room temperature

Nanoscale ◽

10.1039/c7nr03906a ◽

2017 ◽

Vol 9 (35) ◽

pp. 13334-13340 ◽

Cited By ~ 12

Author(s):

Hao Zhang ◽

Xiaobin Xu ◽

Haifeng Lin ◽

Muhammad Aizaz Ud Din ◽

Haiqing Wang ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Active Sites ◽

Room Temperature ◽

Catalytic Performance ◽

High Specific Surface Area ◽

Single Walled Nanotubes

Ultrathin nanocrystals generally provide a remarkable catalytic performance due to their high specific surface area and exposure of certain active sites.

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Effective 3D open-channel nanostructures of a MgMn2O4 positive electrode for rechargeable Mg batteries operated at room temperature

Journal of Materials Chemistry A ◽

10.1039/d0ta07974j ◽

2021 ◽

Author(s):

Kazuki Sone ◽

Yoshihiro Hayashi ◽

Toshihiko Mandai ◽

Shunsuke Yagi ◽

Yuya Oaki ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Room Temperature ◽

Open Channel ◽

Positive Electrode ◽

Large Specific Surface Area ◽

Channel Network ◽

Coin Cell

Room-temperature operations of rechargeable Mg coin-cell batteries have been achieved using a spinel MgMn2O4 powder having a large specific surface area > 200 m2 g–1 and more than 90% porosity with a triple-tiered 3D open-channel network.

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Properties of Silicon Dioxide Amorphous Nanopowder Produced by Pulsed Electron Beam Evaporation

Journal of Nanotechnology ◽

10.1155/2015/417817 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 6

Author(s):

Vladislav G. Il’ves ◽

Michael G. Zuev ◽

Sergey Yu. Sokovnin

Keyword(s):

Optical Properties ◽

Electron Beam ◽

Silicon Dioxide ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Room Temperature ◽

Luminescent Properties ◽

Electron Beam Evaporation ◽

Pulsed Electron Beam

SiO2amorphous nanopowder (NP) is produced with the specific surface area of 154 m2/g by means of evaporation by a pulsed electron beam aimed at Aerosil 90 pyrogenic amorphous NP (90 m2/g) as a target. SiO2NP nanoparticles showed improved magnetic, thermal, and optical properties in comparison to Aerosil 90 NP. Possible reasons of emergence of d0ferromagnetism at the room temperature in SiO2amorphous NP are discussed. Photoluminescent and cathode luminescent properties of the SiO2NP were investigated.

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