scholarly journals Carbon-Based Nanocomposites as Fenton-Like Catalysts in Wastewater Treatment Applications: A Review

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2643
Author(s):  
Ling Xin ◽  
Jiwei Hu ◽  
Yiqiu Xiang ◽  
Caifang Li ◽  
Liya Fu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wastewater Treatment ◽  
Free Radicals ◽  
Organic Pollutants ◽  
Transition Metal Ions ◽  
Future Research ◽  
Hydroxyl Groups ◽  
Edge Structure ◽  
Transmission Electron

Advanced oxidation (e.g., fenton-like reagent oxidation and ozone oxidation) is a highly important technology that uses strong oxidizing free radicals to degrade organic pollutants and mineralize them. The fenton-like reactions have the characteristics of low cost, simple operation, thorough reaction and no secondary pollution. Fenton-like reagents refer to a strong oxidation system composed of transition metal ions (e.g., Fe3+, Mn2+ and Ag+) and oxidants (hydrogen peroxide, potassium persulfate, sodium persulfate, etc). Graphene and carbon nanotube possess a distinctive mechanical strength, flexibility, electrical and thermal conductivity and a very large specific surface area, which can work as an excellent carrier to disperse the catalyst and prevent its agglomeration. Fullerene can synergize with iron-based materials to promote the reaction of hydroxyl groups with organic pollutants and enhance the catalytic effect. Fenton-like catalysts influence the catalytic behavior by inducing electron transfer under strong interactions with the support. Due to the short lifespan of free radicals, the treatment effect is usually enhanced with the assistance of external conditions (ultraviolet and electric fields) to expand the application of fenton-like catalysts in water treatment. There are mainly light-fenton, electro-fenton and photoelectric-fenton methods. Fenton-like catalysts can be prepared by hydrothermal method, impregnation and coordination-precipitation approaches. The structures and properties of the catalysts are characterized by a variety of techniques, such as high-resolution transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption near-edge structure spectroscopy. In this paper, we review the mechanisms, preparation methods, characterizations and applications status of fenton-like reagents in industrial wastewater treatment, and summarize the recycling of these catalysts and describe prospects for their future research directions.

scholarly journals Applications of in situ electron microscopy in oxygen electrocatalysis

2022 ◽  
Author(s):  
Zhi-Peng Wu ◽  
Hui Zhang ◽  
Cailing Chen ◽  
Guanxing Li ◽  
Yu Han
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Degradation Mechanism ◽  
Structural Evolution ◽  
Reduction Reaction ◽  
Future Research ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
In Situ Electron Microscopy

Oxygen electrocatalysis involving the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a vital role in cutting-edge energy conversion and storage technologies. In situ studies of the evolution of catalysts during oxygen electrocatalysis can provide important insights into their structure - activity relationships and stabilities under working conditions. Among the various in situ characterization tools available, in situ electron microscopy has the unique ability to perform structural and compositional analyzes with high spatial resolution. In this review, we present the latest developments in in situ and quasi-in situ electron microscopic techniques, including identical location electron microscopy, in situ liquid cell (scanning) transmission electron microscopy and in situ environmental transmission electron microscopy, and elaborate their applications in the ORR and OER. Our discussion centers on the degradation mechanism, structural evolution and structure - performance correlations of electrocatalysts. Finally, we summarize the earlier discussions and share our perspectives on the current challenges and future research directions of using in situ electron microscopy to explore oxygen electrocatalysis and related processes.

Energy-filtering Transmission Electron Microscopy in materials and life science

1994 ◽  
Vol 52 ◽  
pp. 936-937
Author(s):  
L. Reimer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Analytical Electron Microscopy ◽  
Edge Structure ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Plasmon Loss ◽  
Electron Energy Loss

Energy-filtering transmission electron microscopy can be realized by an imaging filter lens in thecolumn of a TEM, a post-column electron energy-loss spectrometer or a dedicated STEM. This offers new possibilities in analytical electron microscopy by combining the operation modes of electron-spectroscopic imaging (ESI), electron-spectroscopic diffraction (ESD) and the record of an electron energy-loss spectrum (EELS).ESI can be used in the zero-loss mode to remove all inelastically scattered electrons. Thicker amorphous and crystalline specimens can be observed without chromatic aberration and with a transmissionof 10−3 up to 80(110) and 150(200) μg/cm2 at 80(120) keV, respectively. This results in a condiserable increase of scattering, phase and Bragg contrast, especially for low Z material because the ratio of inelastic-to-elastic cross section increases as 20/Z with decreasing atomic number. In future energy-filtered high-resolution crystal-lattice images will offer us a better comparison with dynamical simulations. Plasmon loss filtering can be applied for a better separation of phases (e.g. precipitates in a matrix), which differ in their plasmon loss by about 1 eV. Owing to intersections of the energy loss spectra, different parts of a specimen can change their contrast when tuning the selected energy window. Structures containing non carbon atoms will beconsiderably increased in a bright field like contrast relative to the carboneous matrix just below the carbon K edge (structure—sensitive imaging).

Flocculation characteristics of organo-modified clay particles in poly(L-lactide) / montmorillonite hybrid systems

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Pham Hoai Nam ◽  
Atsuhiro Fujimori ◽  
Toru Masuko
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrogen Bonding ◽  
Hybrid Systems ◽  
Hydroxyl Groups ◽  
Clay Particles ◽  
Modified Clay ◽  
Modified Montmorillonite ◽  
Transmission Electron ◽  
Ft Ir

Abstract The stacking characteristics of organo-modified montmorillonite particles in poly(L-lactide) / clay hybrids have been investigated through FT-IR measurements and transmission electron microscopy. The clay particles tend to flocculate with hydrogen bonding among the hydroxyl groups of the surfactant, those located at the edge of clay particles, and/or those existing at the ends of polylactide chains.

scholarly journals New Insight on the Hydrogen Absorption Evolution of the Mg–Fe–H System under Equilibrium Conditions

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 967 ◽  
Author(s):  
Julián Puszkiel ◽  
M. Castro Riglos ◽  
José Ramallo-López ◽  
Martin Mizrahi ◽  
Thomas Gemming ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Formation Mechanism ◽  
X Ray Diffraction ◽  
Equilibrium Conditions ◽  
Edge Structure ◽  
X Ray ◽  
Solid Diffusion ◽  
Transmission Electron ◽  
Scanning Transmission

Mg2FeH6 is regarded as potential hydrogen and thermochemical storage medium due to its high volumetric hydrogen (150 kg/m3) and energy (0.49 kWh/L) densities. In this work, the mechanism of formation of Mg2FeH6 under equilibrium conditions is thoroughly investigated applying volumetric measurements, X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and the combination of scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HR-TEM). Starting from a 2Mg:Fe stoichiometric powder ratio, thorough characterizations of samples taken at different states upon hydrogenation under equilibrium conditions confirm that the formation mechanism of Mg2FeH6 occurs from elemental Mg and Fe by columnar nucleation of the complex hydride at boundaries of the Fe seeds. The formation of MgH2 is enhanced by the presence of Fe. However, MgH2 does not take part as intermediate for the formation of Mg2FeH6 and acts as solid-solid diffusion barrier which hinders the complete formation of Mg2FeH6. This work provides novel insight about the formation mechanism of Mg2FeH6.

Microstructural investigation of the Carancas meteorite

2010 ◽  
Vol 10 (2) ◽  
pp. 105-112 ◽  
Author(s):  
Kani Rauf ◽  
Anthony Hann ◽  
Chandra Wickramasinghe ◽  
Barry E. DiGregorio
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Intermediate Zone ◽  
Hydroxyl Groups ◽  
X Rays ◽  
Microstructural Investigation ◽  
Dark Zone ◽  
Transmission Electron ◽  
Scanning Electron

AbstractParticles in the Carancas meteorite were examined by electron microscopy (transmission electron microscopy/scanning electron microscopy), energy dispersive analysis of X-rays (EDAX) and Fourier Transform Infrared spectroscopy. Scanning electron microscopical observations reveal that the particles of variable sizes have a stony appearance. Many of these particles show fractures in places, thus confirming an ealier observation that the meteorite was subjected to a high-velocity impact. The outer rim of many aggregates displays a mud crack-like texture. At high magifications, this texture shows ovoid and elongated features, which appear similar to microfossils found in other meteorites.As revealed by both scanning and transmission electron microscopy, some particles show three clearly marked zones, distinguishable by their differences in electron density and texture: a light zone, a dark zone and an intermediate zone. The EDAX analysis of these particles shows that the light zone is composed of silicates rich in Fe, Ni and S (the elements of troilite and pentlandite). The dark zone contains high concentrations of Mg and Si (the major elements of high-temperature minerals, such as forsterite, Mg2SiO4 and enstatite, MgSiO3) intermixed with carbonates and traces of Al, Ca and Na. The intermediate zone also contains high-temperature minerals and Fe-Ni rich silicates.The Carancas meteorite produces an infrared waveband showing prominent features of some carbonate species, amorphous and crystalline silicates, and olivine groups. Hydrated silicates and hydroxyl groups are less abundant, as shown by the presence of small humps between 2.5 and 8.0 μm.The abundance of high-temperature minerals and iron-rich metal confirms an earlier observation that the meteorite is an ordinary H4/5 chondrite. Some particles in the Carancas meteorite are found to have structural and chemical characteristics similar to those of the 81P/Wild 2 comet.

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