• Carbon letters
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• 제7권1호
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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.

• Carbon letters
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• 제6권4호
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• pp.248-254
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• 2005

Silver impregnated activated carbon fibers were post-modified using hydrochloric acid. Adsorption behaviors, SEM morphologies, and functional groups for the silver impregnated ACFs were compared with those of post-modified ACFs. Adsorption isotherms were used to characterize $S_{BET}$, the pore structure and volume of silver-activated carbon fibers (ACFs) before and after acid post-treatment. In order to the reveal the causes of the differences surface states after the samples were washed with hydrochloric acid, outer surface and pore structure were investigated by SEM. And the type and quality of various functional groups were studied from FT-IR spectra and Boehm titration method. Finally, the quantitative properties in silver contents were also examined by EDX spectra.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1189-1194
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• 2004

The adsorption isotherms of N2 onto the metallic silver treated activated carbon fiber samples after acid treatment are Type I with a small amount of capillary condensation hysteresis. Increasing amount of acid treatment leads to a decrease in SBETs and external surface area. But, micropore volume and average pore diameter are presented in constant regular values with increasing amount of sulfuric acid treatment. SEM observes the surface morphology and crystal grown state of metal on the fiber surface. The results of EDX of Ag-activated carbon fiber pre-treated with acid show the spectra corresponding to almost all samples rich in silver with increasing the amount of acid treated. The FT-IR spectra of Ag-activated carbon fiber show that the acid pre-treatment is consequently associated with the homogeneous dispersion of metal with the increased surface acidity of the activated carbon fiber. The type and quality of oxygen groups are determined with Boehm titration method. From the those results, a positive influence of the acidic groups on the carbon fiber surface by acid treatment is also demonstrated by an increase in the contents of metallic silver with increasing of acidic groups.

• 분석과학
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• 제18권4호
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• pp.355-361
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• 2005

본 연구는 인산의 전처리에 의한 두 종류의 활성탄소섬유의 특성 변화와 여기에 칼륨을 처리하여 표면 특성을 비교하고자 하였다. X-선 회절 패턴은 인산을 전처리함에 따라 칼륨종을 포함하는 활성탄소섬유에 대한 금속과 금속염의 존재에 대한 좋은 결과를 나타내었다. 인산을 처리한 후에 표면특성과 비표면적 변화에 차이의 원인을 나타내기 위하여, 동공구조와 표면 모폴로지를 흡착분석과 SEM에 의하여 연구하였다. 인산을 가지고 전처리한 활성탄소섬유의 칼륨 처리효과에 대한 화학적 구성에 대한 원소분석을 위하여 EDX를 사용하였다. 최종적으로, 산소를 포함하는 기능기의 형태와 정성분석은 Boehm에 의하여 제안된 방법으로 부터 결정하였다.

• 분석과학
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• 제19권2호
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• pp.121-130
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• 2006

In this study, silver pre-treated activated carbons are transformed using sulfuric acid. From the results of adsorption, each isotherm shows a distinct knee band, which is characteristic of microporous adsorbents with capillary condensation in micropores. In order to reveal the causes of the differences in adsorption capacity and specific surface area after the samples were washed with various strengths of sulfuric acid, surface morphology and external pore structure were investigated by SEM. X-ray diffraction patterns indicated that Ag-activated carbons show better performance for silver and silver compounds removal by post-treatment with acid. The FT-IR spectra of silver-activated carbon samples show that the acid post-treatment was consequently associated with the removal of silver with an increased surface functional group containing oxygen of the activated carbon. The type and quality of oxygen groups are determined on the method proposed by Boehm. For the chemical composition microanalysis of silver-activated carbons transformed by post-treatment with sulfuric acid, samples were analyzed by EDX.

• Carbon letters
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• 제8권2호
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• pp.108-114
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• 2007

In this work, activated carbon (AC) after $HNO_3$ modification was used as the support during the production of supported $TiO_2$ to increase the high deposition efficiency and the photocatalytic activity. The results of $N_2$ adsorption showed that the BET surface area of samples decreased with an increasing of the concentration of $HNO_3$ due to the penetration of $TiO_2$. From XRD data, a single crystal structure of anatase peak was observed in diffraction patterns for the AC coated with titanium complexes. From the SEM results, almost all particles were aggregated with each other at the carbon surface and AC was covered with $TiO_2$ particles in all of the samples. The EDX spectra show the presence of C, O, Ti and other elements. It was also observed a decreasing of amount of C content with increasing Ti and O content from the EDX. The results of FT-IR revealed that the modified AC contained more surface oxygen bearing groups than that of the original AC. The effect of surface acidity and basity calculated from Boehm titration method was also evaluated from correlations as a function of NaOH, $NaHCO_3$, and $Na_2CO_3$ uptake. The surface modification of AC by $HNO_3$ leads to an increase in the catalytic efficiency of AC/$TiO_2$ catalysts, and the catalytic efficiency increases with increasing of $HNO_3$ concentration.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.229.1-229.1
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• 2010

We investigated the effect of chemical acid treatments on hydrogen storage behaviors of the ordered mesoporous carbons (MCs). The surface functional groups and specific elements of the MCs were characterized with Fourier Transform Infrared (FT-IR) spectrometry and X-ray photoelectron spectroscopy (XPS). Also, the changes in the surface functional groups of the MCs were quantitatively detected by Boehm's titration method. The structural properties of the MCs were investigated using X-ray diffraction (XRD). The hydrogen adsorption capacity of the MCs was evaluated by means of adsorption isotherms at 77 K/1 bar. The formation of surface functional groups by the acidic treatments could influence on the hydrogen storage capacity of the MCs.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.304-304
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• 2009

In this study, the adsorption behaviors of mercury ions on the electroless Cu-plated activated carbons have been investigated. The amount of copper on activated carbons have been confirmed by atomic absorption spectrophotometer (AAS). The surface properties of the ACs studied have been characterized by using Boehm's titration method and scanning electron microscopy (SEM).Experimental results showed the adsorption capacity of mercury ions was increased as the electroless Cu plating. This was probably due to the introduction of copper on ACs leaded to an increase in the surface basicity.

• 한국전기전자재료학회논문지
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• 제23권1호
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• pp.65-69
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• 2010

In this study, we compared two methods(an acid treatment in strong acid reflux and a heat treatment in air atmosphere) for hydrophilic surface treatment of multi-walled carbon nanotubes(MWNT) to enhance the capcity of $RuO_2$/MWNT composite electrode materials for ultracapacitor. Both treatments generated a number of defects on the surface of MWNT by the breakage of $\pi$ bond in graphene layer at which carboxyl groups were introduced. However, the degree of hydrophilicity generated by strong acid treatment was higher than that by heat treatment in air, which was revealed by the quantitative measurement of surface carboxyl groups by using Boehm titration. The increased hydrophilicity save rise to an improved dispersity of $RuO_2$ nanoparticles on MWNT. Finally, the improved dispersity resulted in the capacity enhancement of composite electrode materials for ultracapacitor.

• Korean Chemical Engineering Research
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• 제50권6호
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• pp.1043-1048
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• 2012

본 논문에서는 전기이중층 커패시터(EDLC, Electrical Double Layer Capacitor)의 전극소재로 쓰이는 활성탄소의 안정화를 위해 산소함유관능기를 최소화하고 질소함유관능기의 도입을 통해 유기용액계의 전해질을 가지는 EDLC의 축전용량을 개선하는 연구를 하였다. 주사전자현미경(SEM, Scanning Electron Microscopy), 후리에 변환 적외선분광기(FTIR, Fourier Transform Infrared), 자동원소분석기(EA, Elemental Analysis), 보엠(Boehm) 적정법, 충 방전 테스트 등의 분석법을 이용하여 그 결과를 확인하였다. 산 처리를 통하여 산소함유관능기가 도입되고 요소처리를 통하여 질소함유관능기가 도입되었음을 확인하였다. 질소함유관능기 도입을 통하여 EDLC의 g 당 방전용량을 2 mA 상승시켰으며 빠른 속도로 최대 충 방전 성능을 달성하였다. 반면 산소함유관능기는 전해질 속의 전하가 탄소표면에 흡 탈착되는 것을 방해하기 때문에 낮은 방전용량을 보였고, 충 방전 횟수가 늘어남에 따라 방전용량의 큰 감소를 보여주었다.