• Carbon letters
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• v.14 no.1
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• pp.14-21
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• 2013

Physically and chemically activated carbons (ACs) exhibited high adsorption capacities for organic and inorganic pollutants compared with other adsorbents due to their expanded surface areas and wide pore volume distribution. In this work, seven steam-ACs with different burn-off have been prepared from cotton stalks. The textural properties of these sorbents were determined using nitrogen adsorption at $-196^{\circ}C$. The chemistry of the surface of the present sorbents was characterized by determining the surface functional C-O groups using Fourier transform infrared spectroscopy, surface pH, $pH_{pzc}$, and Boehm's acid-base neutralization method. The textural properties and the morphology of the sorbent surface depend on the percentage of burn-off. The surface acidity and surface basicity are related to the burn-off percentage. A theoretical model was developed to find a mathematical expression that relates the % burn-off to ash content, surface area, and mean pore radius. Also, the chemistry of the carbon surface is related to the % burn-off. A mathematical expression was proposed where % burn-off was taken as an independent factor and the other variable as a dependent factor. This expression allows the choice of the value of % burn-off with required steam-AC properties.

• Journal of Hydrogen and New Energy
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• v.17 no.1
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• pp.47-54
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• 2006

Activated carbon fibers (ACFs) with high surface area and pore volume were modified with metal Ni impregnation and fluorination and investigated hydrogen storage properties by volumetric method. Micropore volume values of ACFs obtained from surface modification with Ni impregnation and fluorination were decreased 9 and 35 %, respectively. Hydrogen storage capacities of fluorinated ACFs were slightly changed, on the other hand, that of Ni impregnated ACF was considerably increased. It means that hydrogen was not only adsorbed on ACF surface, but also on Ni metal surface by means of dissociation. Although the microphone volume of ACF modified with fluorination was decreased, its hydrogen storage were found not to be changed compared with fresh ACF. These results indicated that the surface of ACF after fluorination modification may be strongly attracted hydrogen due to high electronegativity of fluorine. Therefore, it was proven that hydrogen storage capacity was related with micropore volume and surface property of carbon materials as well as specific surface area.

• Carbon letters
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• v.6 no.3
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• pp.166-172
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• 2005

The objective of this study was to investigate the possibility of application for water treatment using the zeocarbon. The zeocarbon was mixture of zeolite and activated carbon. In general, the application of commercial zeocarbon to water treatment is difficult because of weak strength in water and the high pH value of effluents after water treatment. Therefore, we have modified the surface of zeocarbon. For the surface modification, we used the acid treatment to make surface functional group. As a result of modification, was created functional group on zeocarbon surface and was formed mesopore in zeocarbon. The surface modified zeocarbon was applied to removal of nitrogen. In removal experiments of nitrogen, removal efficiency was very high. And, strength of zeocarbon after water treatment and pH of effluents were stabilized. This indicates that the surface modified zeocarbon was easy to recover and reuse. Consequently, our results were shown the possibility of application for water treatment using the surface modified zeocarbon.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1681-1688
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• 2010

Density functional theory was adopted to study the various surface products and their reaction channels focusing on the on-dimer configuration which has not been suggested before. Energetic results show that the most stable on-dimer configuration is the 6,6-[2+2] structure which resembles the typical [2+2] cycloaddition product. The 6,6-[2+2] product is also more stable than any other possible surface structures of inter-dimer configuration further suggesting its existence. Potential energy surface scan along various possible initial surface reactions show that some of the possible on-dimer surface products require virtually no reaction barrier indicating that initial population of on-dimer surface products is thermodynamically determined. Various surface isomerization reaction channels exist further facilitating thermal redistribution of the initial surface products.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.729-733
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• 1998

The surface structure and the pore size distribution of the activated carbon impregnated with silver have been investigated. It has been confirmed that the impregnants had an effect only on the external surface, not on the internal surface and that adsorption isotherms of both impregnated and non-impregnated activated carbons were classified as a typical BET type-I. As the amount of the impregnants increased, the amounts of adsorption, the specific surface area, and the micropore volume decreased and the window blocking was observed. The average pore diameter of the activated carbon impregnated with silver was observed to show the constant values regardless of the amount of the impregnants.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1098-1103
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• 1994

Atomic force microscopy (AFM) images of two conducting layered transition-metal ditellurides, $TaTe_2$ and $Ta_{0.5}$$V_{0.5}$$Te_2$, were examined and their surface and bulk structural features were compared. All the measured unit cell parameters from AFM image were consistent and in complete agreement with the results of the X-ray diffraction. The microscopic structures of corrugated surface tellurium sheets were strongly affected by the modification of metal double zig-zag chains underneath Te surface. Large difference in the height amplitudes of AFM images in $TaTe_2$ and $Ta_{0.5}$$V_{0.5}$$Te_2$ phases was observed and this reflects large difference in the surface electron densities of two phases. On surface, the shorter intralayer Te…Te contacts in $TaTe_2$ induce more electron transfer from Te p-block bands to Ta d-block bands, thus electron density on surface observed in $TaTe_2$ is much lower than that of $Ta_{0.5}$$V_{0.5}$$Te_2$. However, in bulk, interlayer Te…Te contacts in V substituted phase are shorter than those in $TaTe_2$ phase, thus tellurium-to-metal electron transfer occurs more easily in $Ta_{0.5}$$V_{0.5}$$Te_2$ phase.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.219-223
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• 2015

Enhancement of the surface hydrophobicity of polydimethylsiloxane (PDMS) thin films deposited on substrates covered with titanium dioxide ($TiO_2$) nanospheres was studied. First, a low-temperature solution-phase method using polyvinylpyrrolidone (PVP) as a surface capping agent and a water/dimethylformamide (DMF) mixture as the reaction medium was used to synthesize monodisperse $TiO_2$ nanospheres. It was possible to easily control hydrolysis rate of the Ti-precursors and the size of the synthesized nanospheres by varying the amount of PVP and the volume ratio of the solvent mixture. Spray coating of the synthesized $TiO_2$ nanospheres under the PDMS film increased the water contact angle of the film surface to $150.3^{\circ}$. This simple treatment can modify the surface morphology at a nanometer scale without any long or complicated nanoprocess; hence, the surface enters the superhydrophobic Cassie-Baxter regime.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.291-296
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• 1987

Vibrational spectroscopy has been applied to the benzenethiol molecule adsorbed on the silver surface. The results of infrared and Raman spectral studies have led to the conclusion that benzenethiol is chemisorbed dissociatively on the silver surface by rupture of S-H bond and the benzenethiolate formed upon adsorption is bound to silver via its sulfur atom. It seemed more likely that benzenethiol is adsorbed as being inclined to the silver surface. On contact with oxygen, the geometry of the adsorbed species appeared to bear a resemblance to that of silver benzenethiolate salt. The infrared bands of adsorbed species remained with little decrease of intensity even after the prolonged evacuation at 673 K, indicating that benzenethiol is very strongly chemisorbred to the silver surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.248.1-248.1
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• 2014

We present results from an experimental study of conductivity change of poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) film according to the surface structuring. We demonstrate that the patterned structure was enhanced with approximately five times conductivity in comparison with non structure of PEDOT:PSS film. In order to patterning, we have fabricated polystyrene (PS) colloidal monolayer as a template with sphere diameter of 780nm and 1.8um. Structure has honeycomb shape and it provide shorter path way to flowing of electron. Pattern size was controlled by PS diameter and varied by Transformer Coupled Plasma (TCP) etching system. Conductivity was converted from sheet resistance which measured by 4-point prove. Film thickness was derived using Field Emission Scanning Electron Microscopy (FE-SEM) images.

• Journal of the Korean Chemical Society
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• v.8 no.4
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• pp.183-187
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• 1964

The excess molar surface entropies of each surface layers are calculated applying the modified significant structure theory of liquid. The calculated excess molar surface entropy for the first top surface layer is slightly greater than the entropy of surface formation of ideal molecules,$^5$ the latter is equal to Rln2. The excess entropy for the second surface layer is small and that for the third layer is negligible at low temperatures. The surface tensions of argon, nitrogen, methane, benzene and halogens are calculated applying the modified significant structure theory of liquid.