• Carbon letters
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• 제12권2호
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• pp.112-115
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• 2011

The scope of this work investigates the relationship between the amount of oxygen-functional groups and hydrogen adsorption capacity with different concentrations of phosphoric acid. The amount of oxygen-functional groups of activated carbons (ACs) is characterized by X-ray photoelectron spectroscopy. The effects of chemical treatments on the pore structures of ACs are investigated by $N_2$/77 K adsorption isotherms. The hydrogen adsorption capacity is measured by $H_2$ isothermal adsorption at 298 K and 100 bar. In the results, the specific surface area and pore volume slightly decreased with the chemical treatments due to the pore collapsing behaviors, but the hydrogen storage capacity was increased by the oxygen-functional group characteristics of AC surfaces, resulting from enhanced electron acceptor-donor interaction at interfaces.

• Carbon letters
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• 제4권3호
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• pp.140-145
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• 2003

Antibacterial behaviors of PAN-based activated carbon fibers (ACFs) containing silver metal were investigated. The effects of surface and pore structures of the ACFs were studied by $N_2$/77 K adsorption and D-R plot as a function of silver loading content. The antibacterial activities were investigated by a dilution test against Staphylococcus aureus (S. aureus; gram positive) and Klebsiella pnemoniae (K. pnumoniae; gram negative). As experimental results, the ACFs showed some decreases in specific surface areas, micropore volumes, and total pore volume with an increase of silver content. However, the antibacterial activities of the ACFs were strongly increased against S. aureus as well as K. pnumoniae, which could be attributed to the presence of antibacterial metal in the ACFs system.

• Carbon letters
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• 제4권3호
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• pp.126-132
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• 2003

Granular Activated Carbon (GAC) has been proven to be an excellent material for many industrial applications. A systematic study has been carried out of the kinetics of physical as well as chemical activation of phenolic resin chars. Physical activation was carried out using $CO_2$ and chemical activation using KOH as activating agent. There are number of factors which influence the rate of activation. The activation temperature and residence time at HTT varied in the range $550{\sim}1000^{\circ}C$ and $\frac{1}{2}{\sim}8$ hrs respectively. Kinetic studies show that the rate of chemical activation is 10 times faster than physical activation even at much lower temperature. Above study show that the chemical activation process is suitable to prepare granular activated carbon with very high surface area i.e.$ 2895\;m^2/g$ in short duration of time i.e. 1 to 2 hrs at lower temperature i.e. $750^{\circ}C$ from phenolic resins.

• Carbon letters
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• 제13권2호
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• pp.61-72
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• 2012

Dye removal from waste water via adsorption by activated carbons (ACs) developed from agricultural wastes represents an ideal alternative to other expensive treatment options. Physical and chemical ACs were prepared from rice husks. The textural properties of the ACs were characterized by Brunauer-Emmett-Teller-$N_2$ adsorption and scanning electron microscopy. The chemistry of the carbon surface was investigated by Fourier transform infrared spectroscopy, base and acid neutralization capacities, pH of the active carbon slurry, and $pH_{pzc}$. The adsorption capacities of the ACs for the basic dye (methylene blue) and acid dye (acid green 25) were determined using parameters such as contact time, pH, and temperature. NaOH-ACs showed the highest surface area and total pore volume, whereas steam-ACs showed the lowest ones.

• Carbon letters
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• 제4권1호
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• pp.21-23
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• 2003

In this work, the effect of anodic oxidation treatment on Cr(VI) ion adsorption behaviors of activated carbon fibers (ACFs) was investigated. The aqueous solutions of 10 wt% $H_3PO_4$ and $NH_4OH$ were used for acidic and basic electrolytes, respectively. Surface characteristics and textural properties of ACFs were determined by XPS and $N_2$ adsorption at 77 K. The heavy metal adsorption of ACFs was conducted by ICP. As a result, the adsorption amount of the anodized ACFs was improved in order of B-ACFs > A-ACFs > pristine-ACFs. In case of the anodized treated ACFs, the specific surface area was decreased due to the pore blocking or pore destroying by acidic electrolyte. However, the anodic oxidation led to an increase of the Cr(VI) adsorption, which can be attributed to an increase of oxygen-containing functional groups, such as, carboxylic, lactonic, and phenolic groups. It was clearly found that the Cr(VI) adsorption was largely influenced by the surface functional groups, in spite of the reduced specific surface area of the ACFs.

• Carbon letters
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• 제14권4호
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• pp.234-242
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• 2013

Potassium hydroxide-activated carbons (CK21, CK11, and CK12) were prepared from pistachio nutshells. Physicochemical properties of activated carbons were characterized by TGA, $pH_{pzc}$, Fourier transform infrared spectroscopy, scanning electron microscopy, and $N_2$-adsorption at $-196^{\circ}C$. The examinations showed that activated carbons have high surface area ranging between 695-1218 $m^2/g$, total pore volume ranging between 0.527-0.772 mL/g, and a pore radius around 1.4 nm. The presence of acidic and basic surface C-O groups was confirmed. Batch adsorption experiments were carried out to study the effects of adsorbent dosage, temperature, initial concentration of adsorbate, and contact time on deltamethrin adsorption by activated carbons. The kinetic studies showed that the adsorption data followed a pseudo-second order kinetic model. The Langmuir model showed a maximum adsorption capacity of 162.6 mg/g at $35^{\circ}C$ on CK12. Thermodynamic studies indicated that adsorption was spontaneous and increased with temperature, suggesting an endothermic process.

• 전기화학회지
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• 제17권4호
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• pp.216-221
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• 2014

전기 화학적으로 활성화된 glassy carbon 전극을 사용하여 Clenbuterol 의 정량측정을 위해 신속하고 민감한 전압-전류 법을 개발하였다. 시차 펄스 전압-전류 법(Differential pulse voltammetry)을 이용하여, Clenbuterol에 대해 $1{\times}10^{-7}M$에서 $2{\times}10^{-5}M$의 범위에서 선형적인 반응을 보였으며 검출한계는 $6{\times}10^{-9}M$ (S/N = 3)이었다. Clenbuterol 의 농도가 $1{\times}10^{-6}M$에서의 상대표준편차는 4.3%이었다. 다양한 양의Clenbuterol이 포함된 소변 샘플로부터 96%의 회수율을 나타냈다. (N = 3, $5{\times}10^{-7}M$에서 $1{\times}10^{-6}M$의 Clenbuterol)

• Carbon letters
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• 제12권4호
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• pp.236-242
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• 2011

The oxyfluorination effects of activated carbon nanofibers (OFACFs) were investigated for $CO_2$ storage. Electrospun CFs were prepared from a polyacrylonitrile/N,N-dimethylformamide solution via electrospinning and heat treatment. The electrospun CFs were chemically activated in order to generate the pore structure, and then oxyfluorination was used to modify the surface. The samples were labeled CF (electrospun CF), ACF (activated CF), OFACF-1 ($O_2:F_2$ = 7:3), OFACF-2 ($O_2:F_2$ = 5:5) and OFACF-3 ($O_2:F_2$ = 3:7). The functional group of OFACFs was investigated using X-ray photoelectron spectroscopy analysis. The C-F bonds formed on surface of ACFs. The intensities of the C-O peaks increased after oxyfluorination and increased the oxygen content in the reaction gas. The specific surface area, pore volume and pore size of OFACFs were calculated by the Brunauer-Emmett-Teller and density functional theory equation. Through the $N_2$ adsorption isotherm, the specific surface area and pore volume slightly decreased as a result of oxyfluorination treatment. Nevertheless, the $CO_2$ adsorption efficiency of oxyfluorinated ACF improved around 16 wt% due to the semi-ionic interaction effect of surface modificated oxygen functional groups and $CO_2$ molecules.

• 공업화학
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• 제27권1호
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• pp.62-67
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• 2016

본 연구에서는 정수슬러지를 원료로 사용하여 펠렛형 흡착제를 제조하고 질소흡착법, XRD, XRF 및 암모니아 승온탈착법 등을 사용하여 물리 화학적 특성을 분석하였다. 정수슬러지 유래 펠렛형 흡착제와 첨착활성탄의 암모니아 및 포름알데히드 기체의 흡착 성능을 비교하였다. 정수슬러지로부터 제조된 펠렛형 흡착제는 첨착활성탄보다 표면적과 기공부피는 훨씬 작지만 암모니아를 훨씬 더 많이 흡착할 수 있었다. 이는 정수슬러지로부터 제조된 펠렛형 흡착제 표면에 산점이 훨씬 더 많이 분포해 있어서 화학흡착에 의해 암모니아를 흡착하기 때문이다. 반면에, 산성가스인 포름알데히드 가스 흡착의 경우는 넓은 표면적과 발달된 기공으로 인하여 첨착활성탄의 흡착성능이 정수슬러지로부터 제조된 펠렛형 흡착제에 비해 훨씬 우수하였다.

• Journal of Electrochemical Science and Technology
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• 제10권4호
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• pp.387-393
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• 2019

Activated carbons (ACs) are considered important electrode materials for supercapacitors because their large specific surface areas lead to high charging capacities. In the conventional synthesis of ACs, a substantial amount of carbon is lost during carbonization of a precursor. The development of a method to synthesize ACs in high yield would lower their manufacturing cost. Here, we demonstrate the synthesis of high-specific-surface-area NaOH-AC from carbon prepared via a hydrothermal carbonization (HTC) route, with a higher yield than that achieved through conventional pyrolysis carbonization. The amorphous carbon was derived from HTC of sugar and subsequently activated at 800℃ with various NaOH etchant/C ratios under a N₂ atmosphere. The AC prepared at 4:1 NaOH/C exhibited the highest surface area (as high as 2,918 ㎡ g^-1) and the highest specific capacitance (157 F g^-1 in 1 M aqueous Na₂SO₄ electrolyte solution) among the NaOH-AC samples prepared in this work. On the basis of their high specific capacitance, the NaOH-ACs prepared from HTC sugar are suitable for use as electrode materials for supercapacitors.