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The present investigation was undertaken to determine the adsorption properties and evaluate the adsorption capacities of several coal- and wood-based chemically activated carbons using the Dubinin–Radushkevich (DR) characteristic adsorption analysis. Limiting micropore volumes (W 0 ), determined from CCl 4 and acetone adsorption isotherms at room temperature, were generally in good...
New quasi one-dimensional (1D) and dimensionless (0D) objects–nanotubes constructed of C and BN fragments–are considered and their electron spectra are computed by the method of crystal orbitals. Main and mini-zone gaps are shown to be considerably varied for (n,0) zigzag tube superlattices with C 2kn BN ln (l,k=1,…) unit cells when C (or BN) fragment length is changed. Dot and interface...
The oxidation behavior of B 4 C–SiC/C composites of various compositions at temperatures up to 1500°C was analyzed by the thermal gravimetric/differential thermal analysis (TG/DTA) technique and the surface morphology of the composites after isothermal oxidation at 800, 1000 and 1200°C was examined by scanning electron microscopy. The results indicated that the composites exhibited variable...
NH 3 and H 2 S adsorption studies on coal- and wood-based chemically activated carbons were carried out at room temperature using a gravimetric adsorption technique. The adsorption capacity of NH 3 and H 2 S in the very low relative pressure range was independent of the surface area development. Activated carbons with lower surface area generally adsorbed more of these...
This study is concerned with the preparation of high carbon yield coal-tar pitches by tar air-blowing under pressure (0.5MPa). The influence of the temperature (275–325°C), reaction time (0–20h) and air flow (60–120lh −1 ) on pitch composition and properties were monitored by elemental analysis, solubility measurements and Fourier transform infrared spectroscopy. Pyrolysis behaviour of parent...
Moulding and successive carbonization of the toluene-insoluble fraction in fullerene soot were studied to prepare carbon disks with unique properties. Separation of the graphitic component by precipitation in acetone allows the fraction to be moulded and carbonized into a carbon disk of significant strength. The disk was found to consist of large grains and fine particles which were densely packed...
The polymer was prepared by γ-ray induced polymerization in air and pyrolysis under argon at various temperatures in the range 600–900°C. The content in the carbon and oxygen increases at the expense of decreasing content in nitrogen and hydrogen. The ferromagnetic phase separated from the residue resulted by the pyrolysis of polyacrylonitrile has been analysed using Fourier transform infrared, X-ray...
Adsorption studies of mercury (II) from aqueous solutions on coirpith carbon were investigated under the varying conditions of agitation time, metal ion concentration, adsorbent dose and pH. Adsorption equilibrium reached in 10, 25, 30 and 40min for 10, 20, 30 and 40mgl −1 Hg(II) concentration. Adsorption followed both Langmuir and Freundlich isotherms. The adsorption capacity was 154mgg ...
Multiwalled carbon nanotubes (MWNT) have been obtained by catalytic decomposition of acetylene at 900°C over silica supported cobalt. The thermal treatment at 1600, 2000 and 2800°C allowed improvement of their structural and microtextural organization as well as the elimination of any remaining nanoparticles of cobalt. Such a tubular carbon host with graded texture and chemical composition is a very...
Raman and infrared spectra of the three Tm@C 82 isomers and of Gd@C 82 were used to study the electronic state of endohedral fullerenes. It is shown that the determination of the electronic state is possible from the wave number of the metal cage Raman mode below 200cm −1 . Moreover a significant influence of the C 82 cage structure on the internal vibrations of the...
X-ray photoelectron spectroscopy (XPS) was employed to evaluate the surface element distribution/concentration and surface chemical structure of coal- and wood-based chemically activated carbons and to investigate the effect of these features on the adsorption of water vapor at low relative pressure and room temperature. It was found that high surface area carbon samples generally show low concentrations...
In the process of produce carbon materials by pyrolyzing polycarbodiimide (PCDI), the starting PCDI is preliminarily stabilized by a low temperature treatment in an oxidative atmosphere. In this study, the relation between the carbonization behavior of PCDI films and the stabilization conditions was investigated with the aim of optimizing stabilization conditions. The extent of stabilization was evaluated...
Adsorption equilibria of chloropentafluoroethane (CF 3 CF 2 Cl, CFC-115) on Pd/activated carbon powder and on activated carbon powder were examined between 298.15 and 373.15K. The adsorption equilibria of CFC-115 on the Pd/activated carbon powder and the activated carbon powder can be well represented by the BET equation. The isosteric heats of adsorption of CFC-115 on both adsorbents...
Tantalum(V) chloride was intercalated from the gas phase into highly oriented pyrolytic graphite and into natural graphite. Second stage intercalation compounds were produced. The TaCl 5 –graphite intercalation compounds were heated in a hydrogen atmosphere for 1week at 200°C. The flakes showed no exfoliation, but reduction was insufficient at this temperature. A reduction for 1week at 1000°C...
Three series of porous carbon fibers were prepared by electrochemical oxidation of a synthetic polyacrylonitrile-based fiber to various degrees. The electrooxidized fibers were characterized by N 2 adsorption at 77K, CO 2 adsorption at 273K, NaOH neutralization and X-ray photoelectron spectroscopy (XPS). In all cases standard BET surface areas calculated from nitrogen adsorption data...
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