• 한국광물학회지
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• 제15권3호
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• pp.195-204
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• 2002

광물조성과 노출표면적(exposed surface area)은 토양풍화속도 계산모델에 영향을 미치는 중요한 요인들이다. PROFILE 등 기존의 풍화속도 계산모델에서는 입도분석자료에 기초한 기하학적 계산값이나 $N_2$-BET 비표면적 등을 그대로 노출표면적으로 적용하고 있다. 그러나, 토양은 광물과 유기물의 혼합체로써 노출표면적을 정확히 구하기는 상당히 어려운 것이 사실이다. 본 연구에서는 유기물의 영향에 의한 토양광물의 노출표면적변화를 토양 깊이에 따른 peroxidation 전후의 N2-BET 비표면적값을 통해 살펴보고, 토양칼럼실험을 이용하여 풍화속도의 차이를 살펴보았다. 실험결과 peroxidation 후의 $N_2$-BET 비표면적은 1.68~4.87 $m^2$/g의 범위에서 증가하였으며, 깊이에 따라 증가하는 범위가 감소하는 경향을 보여주었다 이는 부식산 등 토양표면에 농집되어 존재하는 다양한 형태의 유기산 등이 광물의 노출표면적을 감소시키고 있다는 것을 의미한다고 할 수 있다 기존의 토양풍화속도 모델에서 토양광물 노출표면적변화 계산에 있어서 광물-유기산간의 결합에 의한 영향을 결합세기 측면에서 고려하고 정량화 하는 것이 향후과제라고 생각된다.

• 분석과학
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• 제24권6호
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• pp.503-509
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• 2011

비표면적은 기능성 나노소재의 특성평가에 있어 매우 중요한 지표가 되고 있다. 하지만 비표면적 측정은 측정방법 및 해석 방법에 따라 결과에 많은 차이가 있어왔다. 국내에 보급된 비표면적 측정장치의 신뢰성 검증을 위하여, 21개 산학연 기관을 대상으로 순회평가(RRT)를 수행하였다. 순회평가 분석 결과 많은 기관에서는 비표면적 측정장비의 흡착량 측정 성능에 문제가 있음을 확인 하였으며, 이는 인증기준물질의 필요성을 확인시켜 주었다. 또한 BET 분석방법이 분석자의 주관에 의해 많이 좌우됨을 확인 하였다. 즉 BET 분석구간의 선택영역에 따라 CRM I의 경우 16% 까지 차이를 줄 수 있음을 확인하였는데, 이는 적정한 BET 구간의 선택을 위한 BET 매개변수 C 값과 fitting 상관계수 R 값에 대한 기준이 필요함을 확인시켜 주었다. 이러한 순회평가의 경험과 검증된 비표면적 인증물질 및 표준 절차서의 보급은 산업계에 신뢰성 있는 비표면적 측정결과를 주게 됨으로서, 일관성 있는 공정운용에 의한 품질관리, 생산성 향상, 안정성 판단 및 신제품 개발 등에 기여할 것이다.

• 한국전기전자재료학회논문지
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• 제31권2호
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• pp.112-116
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• 2018

Electric double layer capacitors (EDLCs) are promising candidates for energy storage devices in electronic applications. An EDLC yields high power density but has low specific capacitance. Carbon material is used in EDLCs owing to its large specific surface area, large pore volume, and good mechanical stability. Consequently, the use of carbon materials for EDLC electrodes has attracted considerable research interest. In this paper, in order to evaluate the electrochemical performance, graphene is used as an EDLC electrode with flake sizes of 3, 12, and 60 nm. The surface characteristic and electrochemical properties of graphene were investigated using SEM, BET, and cyclic voltammetry. The specific capacitance of the graphene based EDLC was measured in a 1 M $TEABF_4/ACN$ electrolyte at the scan rates of 2, 10, and 50 mV/s. The 3 nm graphene electrode had the highest specific capacitance (68.9 F/g) compared to other samples. This result was attributed to graphene's large surface area and meso-pore volume. Therefore, large surface area and meso-pore volume effectively enhances the specific capacitance of EDLCs.

• 임산에너지
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• 제21권2호
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• pp.1-9
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• 2002

소용량 실험실용 탄화로 및 3종류의 대형 탄화로 (간이 탄화로 (400 - 500℃), 개량 탄화로(600 - 700℃) 및 전용탄화로 (800 - 1,000℃))를 이용하여 소나무 수피의 탄화를 실시하였다 그리고 제조된 수피탄의 물성과 세공구조를 분석하였다. 소나무 수피를 실험실용 소용량 탄화로를 이용하여 질소 존재하에서 500℃에서 900℃까지의 다양한 온도 조건에서 탄화시키면, 탄화수율은 탄화 온도의 증가와 함께 급속하게 낮아졌으며, 700 - 900℃에서 일정하게 유지되었다. 수피의 탄화수율은 동일 탄화온도에서 소나무 목부의 탄화수율보다 16 - 18％더 높았다. 제조된 수피탄의 BET 비표면적은 탄화수율 약 35 - 40％에서 약400 - 500㎡／g 을 나타내었다. 600℃ 30분의 탄화조건에서 제조된 소나무 목부탄은 미세공이 많이 발달해 있었으나, 동일조건에서 제조된 수피탄이 경우 미세공은 물론 중세공도 많이 존재하였다. 대형 탄화로에서 제조된 수피탄의 탄화 수율 및 요오드가 및 BET 비표면적은 소용량 탄화로의 결과와 매우 유사하였다. 이러한 결과는 소나무 수피가 높은 비표면적과 수율을 가지는 양질의 숯을 생산 할 수 있는 원료로 사용될 수 있음을 나타낸다.

• Carbon letters
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• 제4권1호
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• pp.31-35
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• 2003

The specific adsorption behaviors of activated carbons (ACs) treated with 30 wt% $H_3PO_4$ or NaOH were investigated in the removals of NO or $NH_3$. The acid and base values were determined by Boehm's titration method. And, the surface properties of ACs were studied by FT-IR and XPS analyses. Also, $N_2/77K$ adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET and t-plot methods, respectively. From the adsorption tests of NO and $NH_3$, it was revealed in the case of acidic treatment on ACs that the $NH_3$ removal was more effective due to the increase of acidic functional groups in carbon surfaces. Also, the NO removal was increased, in the case of basic treatment, due to the improvement of basic functional groups, in spite of significant decreases of BET's specific surface area and total pore volume. It was found that the adsorption capacity of ACs was not only determined by the textural characteristics but also correlated with the surface functional groups in the acid-base intermolecular interactions.

• 한국재료학회지
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• 제9권4호
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• pp.362-367
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• 1999

We intended to make the activated carbon fibers which could separate, remove and recover the volatile organic compounds of benzene, toluene, acetone and methanol. Changing activation temperature and time, large specific surface area and narrow pore distribution could be obtained. The activated carbon fibers have large adsorption capacity and selectivility for those organic compounds. We characterized the adsorption capability of the activated carbon fibers for benzene, toluene, acetone and methanol by BET specific surface area and pore size and micropore volume measurements. In the result of activation, the maximum value of BET specific surface area of the fibers was $1100\m^2$/g at $800^{\circ}C$ for 60 minutes and $K_2$O was reduced actively in this condition. Their average pore size was 5.8~5.9$\AA$. The activated carbon fibers prepared in this work had high adsorption rate to saturation and the selectibility for the above organic compounds. The adsorbed amount of acetone and methanol(diameter of$ 4.3\AA$ and $4.4\AA$ respectively) which are smaller than micropore diameter in size was 43~49%, which was larger value than benzene and toluene(in the same diameter as $5.9\AA$).

• 한국응용과학기술학회지
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• 제28권2호
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• pp.225-231
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• 2011

The electrochemical characteristics of electric double layer capacitor(EDLC) were investigated using various carbon materials. The physical properties such as specific surface area and mean pore size of activated carbon were analyzed by BET. The results of the activated carbon used for electrode material showed that the specific surface areas varied from 600 to 1500 $m^2$/g and mean pore sizes from 1.74 to 2.88 nm. A maximum specific capacitance of 0.30 F/$cm^2$ was obtained for the activated carbon with the highest specific surface area and ionic conductivity. Also, it was found that the electrochemical results of the cyclic charge-discharge tests were stable.

• 한국세라믹학회지
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• 제53권1호
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• pp.93-98
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• 2016

Cold plasma and heat treatment were selected as technologies to reduce unburned carbon in fly ash to less than 1.0%. Both cold plasma and heat treatment made it possible to eliminate unburned carbon to less than 1.0%. In the case of fly ash, which almost entirely eliminated unburned carbon with an ignition loss of 0.5%, heat treatment caused adhesion among particles and the BET specific surface area rapidly decreased as the mean particle size increased. On the other hand, with cold plasma, unburned carbon elimination caused the BET specific surface area to decrease and, as no adhesion occurred among particles, the mean particle size became small. Also, cold plasma treatment allowed small spherical particles confined within the unburned carbon particles to be released with the elimination of the unburned carbon frame, so that the quantity of fine particles had a tendency to slightly increase.

• Carbon letters
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• 제5권2호
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• pp.51-54
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• 2004

Isotropic pitch-based carbon fiber was isothermally activated in $CO_2$ atmosphere. Structural parameters of the isotropic carbon fibers and activated carbon fibers (ACFs) were evaluated by X-ray diffraction (XRD). The $d_{002}$ and La of the carbon fibers were measured to be 4.04 ${\AA}$ and 23.6 ${\AA}$ and those of ACFs were 4.29 ${\AA}$ and 22.7 ${\AA}$, respectively, representing less ordered through activation process. The pores in the ACFs were characterized by BET, and they showed super-high specific surface area of maximum value 3,495 $m^2/g$ from average pore size of 8.3 ${\AA}$ at 59% burn-off. It was recognized that 8-9 ${\AA}$ was optimum range of pore size for efficient creation of high specific surface area. The average size of the pores formed at higher temperature ($1100^{\circ}C$) was larger than that of the pores formed at lower temperature ($900^{\circ}C$).

• 한국환경과학회지
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• 제19권6호
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• pp.681-687
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• 2010

Mesoporous silica was prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide (CTMABr) as a surfactant. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of mesoporous silica were determined by XRD, SEM, TEM and BET. Also, surface potential of mesoporous silica was measured using zeta potential. $N_2$ adsorption isotherm characteristics, including the specific surface area ($S_{BET}$), total pore volume $V_T$), and average pore diameter ($D_{BJH}$), were determined by BET. As a result, SBET of $100m^2/g{\sim}1500m^2/g$ was determined from the $N_2$ adsorption isotherm. Also, the average pore diameter was 2 nm∼4 nm. Mesoporous silica's surface potential of minus charge was determined from zeta potential.