• Carbon letters
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• v.10 no.3
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• pp.181-189
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• 2009

Activated carbon spheres (ACS) were prepared at different heating rates by carbonization of the resole-type phenolic beads (PB) at $950^{\circ}C$ in $N_2$ atmosphere followed by activation of the resultant char at different temperatures for 5 h in $CO_2$ atmosphere. Influence of heating rate on porosity and temperature on carbon structure and porosity of ACS were investigated. Effect of heating rate and temperature on porosity of ACS was also studied from adsorption isotherms of nitrogen at 77 K using BET method. The results revealed that ACS have exhibited a BET surface area and pore volume greater than $2260\;m^2/g$ and $1.63\;cm^3/g$ respectively. The structural characteristics variation of ACS with different temperature was studied using Raman spectroscopy. The results exhibited that amount of disorganized carbon affects both the pore structure and adsorption properties of ACS. ACS were also evaluated for structural information using Fourier Transform Infrared (FTIR) Spectroscopy. ACS were evaluated for chemical composition using CHNS analysis. The ACS prepared different temperatures became more carbonaceous material compared to carbonized material. ACS have possessed well-developed pores structure which were verified by Scanning Electron Microscopy (SEM). SEM micrographs also exhibited that ACS have possessed well-developed micro- and meso-pores structure and the pore size of ACS increased with increasing activation temperature.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.561-567
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• 2009

The Fe-ACF/$TiO_2$ composites were prepared by a sol-gel method and were characterized by nitrogen adsorption, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Energy Dispersive X-ray (EDX). The Fe-ACF/$TiO_2$ composites were developed for the decomposition of organic dyes by using a UV lamp. The decomposition effect was investigated under various conditions, such as three selected non-biodegradable organic dyes like Methylene Blue (MB), Methyl Orange (MO), Rhodamine B (Rh.B), and in the presence of Fe and hydrogen peroxide ($H_2O_2$). The photocatalytic activity was derived from possible combination effects, such as (1) adsorption of ACF, (2) generation of electron/hole by $TiO_2$, (3) photo-Fenton reaction of Fe, and (4) oxidation of $Fe^{2+}\;to\;Fe^{3+}\;by\;H_2O_2$.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.361-364
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• 2002

BAC (biological activated carbon) process is a combination of biodegradation and active carbon adsorption. Pre-ozonation of raw water increased in biodegradable organic fraction. This study is to investigate the enhancement of dissolved organic matter removals by pre-ozonation process combined with BAC process at a semi-pilot scale. By biodegradation improvement in pre-ozonation process. the charge of adsorption was reduced and the life of biological activated carbon is extended. And, 48 % of total DOC was remove in the upper compartment of BAC column. The removal of the nitrogen-ammonia shows a considerably high removal ratio with 75.9 %.

• Journal of the Korean Society of Tobacco Science
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• v.31 no.1
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• pp.9-17
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• 2009

Activated carbon fiber (ACF) was surface modified by nitric acid to improve the adsorption efficiency of the propylamine. Functional groups and textural properties of modified ACF were investigated. The total surface acidity increased about 7 times to that of as-received ACF by modification with 1 M nitric acid solution, carboxylic and phenolic groups mainly increased. However, the specific surface areas and the total pore volumes of the modified ACFs were decreased by 5-8% due to the increased blocking (or demolition) of micropores in the presence of newly introduced complexes. Despite the decrease of textural properties, it was found that the amount of propylamine adsorbed by the modified ACFs was increased by approximately 17%. The oxygen and nitrogen contents on the modified ACF increased by 1.5 and 3 times compared with the as-received ACF. From the XPS results, it was observed that propylamine reacted with strong or weak acidic groups, such as -COOH or -OH on the ACF surfaces, resulting in the formation of pyrrolic-, pyridonic- or pyridine-like structures.

• Journal of the Korean Ceramic Society
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• v.45 no.11
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• pp.651-657
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• 2008

In this study, CNT/$TiO_2$ composites were prepared using surface modified Multiwall carbon nanotube (MWCNT) and titanium n-butoxide (TNB) with benzene. The composites were characterized by nitrogen adsorption isotherms, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), FT-IR spectra, and UV-vis absorption spectroscopy. The UV radiation induced photoactivity of the CNT/$TiO_2$ composites was tested using a fixed concentration of methylene blue (MB, $C_{16}H_{18}N_3S{\cdot}Cl{\cdot}3H_2O$) in an aqueous solution. Finally, it can be considered that the MB removal effect of the CNT/$TiO_2$ composites is not only due to the adsorption effect of MWCNT and photocatalytic degradation of $TiO_2$, but also to electron transfer between MWCNT and $TiO_2$.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.525-530
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• 2014

Titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst was fabricated by decorating ZSM-5 zeolite on the hydrothermally synthesized titanium dioxide via hydrothermal process and subsequent annealing. The catalyst was characterized by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Nitrogen adsorption-desorption (BET). The surface acidity of the catalyst was measured by means of Fourier transform infrared (FT-IR) spectrum of pyridine adsorption. And the catalytic activity for ethanol dehydration to ethylene was evaluated in a continuous flow fixed-bed reactor. Attributed to the increase of the effective surface acid sites caused by titanium dioxide nanotube as electron acceptor, titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst exhibits strongly enhanced activity for ethanol dehydration to ethylene.

• Carbon letters
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• v.7 no.1
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• pp.1-8
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• 2006

The activated carbon "C" was obtained by carbonization followed by activation with steam at 40% of burn-off. Oxidized carbons C-N, C-P and C-H were obtained by oxidizing the activated carbon C with concentrated nitric acid, ammonium peroxysulfate and hydrogen peroxide, respectively. The textural properties of the carbons were determined from nitrogen adsorption at 77 K. The acidic surface functional groups were determined by pH titration, base neutralization capacity and electrophoretic mobility measurements. The cation exchange capacities of un-oxidized and oxidized carbons were determined by the removal of Cu(II) and Ni(II) from their aqueous solutions. The surface area and the total pore volume decreased but the pore radius increased by the treatment of activated carbon with oxidizing agents. These changes were more pronounced in case of oxidation with $HNO_3$. The surface pH of un-oxidized carbon was basic whereas those of the oxidized derivative were acidic. The removal of Cu(II) and Ni(II) was pH dependent and the maximum removal of the both ions was obtained at pH of 5-6. Cu(II) was more adsorbed, a phenomenon which was ascribed to its particular electronic configuration.

• Carbon letters
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• v.7 no.1
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• pp.34-41
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• 2006

The objective of this paper is to compare the variation of surface properties by hydrochloric acid pre-treatment and of metallic potassium and their salts loading effect for activated carbon after surfaces transformation by acid. From the results of nitrogen adsorption, each isotherm shows a distinct knee band, which is closely related to the characteristic of microporous carbons with capillary condensation in micropores. In order to present the causes of the differences in surface properties and $S_{BET}$ after the samples were treated with hydrochloric acid, pore structure and surface morphology are investigated by adsorption analysis. X-ray diffraction (XRD) patterns indicate that activated carbons show better performance for metallic potassium and potassium salts by pre-treatment with hydrochloric acid. Scanning electron microscopy (SEM) pictures of potassium/activated carbon particles provide information about the homogeneous distribution of metal or metal complex on the surface. For the chemical composition microanalysis for potassium treatment of the activated carbon pre-treated with hydrochloric acid, samples were analyzed by energy disperse X-ray (EDX). Finally, the type and quality of oxygen groups are determined from the method proposed by Boehm. A positive influence of the acidic groups on the carbon surface by acid treatment is also demonstrated by an increase in the contents of potassium salts with increasing of acidic groups calculated from Boehm titration.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.249-254
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• 1997

The constructed wetland system which is applicable to rural wastewater treatment was examined by pilot plant experiment. Removal rates of nutrients including nitrogen and phosphorus and total coliform were evaluated. The $NH_4\;^+$ concentration of the influent was in the range of 91.57 to 275.88mg/l and the effluent concentration was about 40% lower than the influent. The decreasing of the $NH_4\;^+$ concentration might be due to volatilization, plant uptake, adsorption onto soil particles, and mainly nitrification. However, generally concentrations of $NO_2\;^-$ and $NO_3\;^-$ were increased in the effluents compared to the influent concentrations, which implies that nitrogen components in the system were nitrified. Overall, the average removal rate of the nitrogen was about 5% which seems inadequate as a wastewater treatment system, and this system needs improvement on nitrogen removal mechamism. The removal rate of the phosphorus was quite high and effluent concentration was very low. Reason for high removal rate of the phosphorus might be mainly strong adsorption characteristic onto soil particles. The average removal rate of the total coliforms was about 83%, and main removal mechanisms are thought to be adsorption onto soil and inability to compete against the established soil microflora. From the results of the study, the constructed wetland system needs to be improved in nitrogen removal mechanism for field application.

• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.44-51
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• 2008

In this study, the effects of carbonization temperature on the physico-chemical properties of Korean red-pine wood (Pinus densiflora S. et Z.) powder charcoal are studied by elemental analysis, nitrogen adsorption-desorption and SEM techniques. The surface structure and physico-chemical properties of the wood charcoal greatly depend on the carbonization temperature and their temperature dependences for sapwood (swd) and heartwood (hwd) are qualitatively analogous. Because of the differences in characteristics such as hardness and composition between heartwood and sapwood, charcoals from heartwood have larger specific surface area and smaller average pore diameter than that from sapwood. Because the decomposition reaction mostly proceeds in the precarbonization stage, the charcoal produced in this stage mainly consists of carbon. The second carbonization reaction is insignificant but still proceeds up to $700^{\circ}C$, and the specific surface area continuously increases. Above $800^{\circ}C$, the surface area is reduced by the pore-filling and narrowing effects and especially above $900^{\circ}C$, new carbon phase with hexagonal column rooted into the pore is formed. The nitrogen adsorption-desorption isotherm of the charcoal is classified as type I and its hysteresis loop was as type H4.