• 공업화학
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• 제30권5호
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• pp.639-642
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• 2019

본 연구에서는 침전법을 이용하여 양이온성 계면활성제인 hexadecyltrimethylammonium chloride (CTAC)를 도입한 수산화인회석을 합성하였다. X-선 회절 분석법과 투과전자현미경, 비표면적 분석기를 이용하여 수산화인회석과 CTAC을 도입한 수산화인회석의 결정성, 형태, 비표면적을 분석하였다. 열처리 후, HAP와 CTAC-HAP는 열처리 전과 비교하여 비표면적이 감소하였다. 또한 열처리는 뾰족한 막대 모양에서 종횡비가 감소한 둥근 모양으로의 CTAC-HAP의 형태변화를 유도하였다. 이러한 형태의 변화는 순수한 HAP에서도 관찰되었다. 그러므로 형태 변화와 열처리 후의 비표면적 감소는 열처리 중 CTAC의 제거로 생성된 기공들이 형태 변화로 인해 유지되지 않는 것으로 판단된다.

• 한국대기환경학회지
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• 제21권4호
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• pp.471-478
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• 2005

The objective of this research is to improve adsorption efficiency of adsorbent made from MSWI (Municipal Solid Waste Incinerator) ny ash by $HNO_3$ activation. The acidity and the basicity were determined by Boehm's method and the surface structure was studied by BET method with N2 adsorption. The adsorption properties were investigated with benzene and MEK (Methylethylketone). $HNO_3$ activation can modify the surface property of an adsorbent such as specific surface area, pore volume, and functional group. According to the results, the specific surface area of the adsorbent was increased from $309.2m^2/g\;to\;553.2 m^2/g$ by activation. Also oxygen-containing functional groups were formed on it.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.683-686
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• 2004

In recent years, the supercapacitor and hybrid capacitor have related with substitutional energy source focused of many scientists because of their usage in power sources for electric vehicles, computers and other electric devices. The storage energy of electrical charge is based on electrostatic interactions in the electric double layer at the electrode/electrolyte interface, resulting in high rate capability and long cycle performance compared with batteries based on Faradaic electrode reactions. So we have been considered to carbon nanofibers as the ideal material for supercapacitors due to their high utilization of specific surface area, good conductivity, chemical stability and other advantages. In this work, we aimed to find out that the capacitance have increased because of electrochemical capacitance to provide by carbon nanofibers. Also carbon nanofibers based on chemical method and water treatment have been resulted larger capacitances and also exhibit better electrochemical behaviors about 15% than before of nontreated state. And also optical observations with treated and nontrteated carbon nanofibers discussed by the TEM, SEM, EDX, BET works and specific surface area analyzer. Their results also focused on the surface area of electrode and electrical capacitance was also improved by the effect of surface treatments.

• 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.

• 한국환경과학회지
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• 제16권9호
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• pp.1091-1098
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• 2007

Activated carbon was prepared from waste citrus peels by chemical activation with $ZnCl_2$. The optimal condition of carbonization was at $300^{\circ}C$ for 1.5 hr. Activation experiments with carbonized samples prepared at optimal carboniztion condition were carried out under various conditions such as activation temperature of 400 to $900^{\circ}C$, activation time of 0.5 to 2.0 hr, and $ZnCl_2$ ratio of 100 to 300%. In order to investigate the physical properties of the activated carbons prepared, iodine adsorptivities and specific surface areas were measured and their morphologies were observed from scanning electron microscopy. As $ZnCl_2$ ratio increased, activation yield decreased, while iodine adsorptivity and specific surface area increased. The optimal condition of activation was at 300% $ZnCl_2$ ratio and $300^{\circ}C$ for 1.5 hr, and then iodine adsorptivity and specific surface area was measured as about 862 mg/g and $756m^2/g$, respectively. SEM photography showed that the surface morphology was changed and many active pore were produced by chemical activation.

• 상하수도학회지
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• 제10권1호
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• pp.112-120
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• 1996

In this study, the porous glass media was utilized as biomass carrier, and the optimum characteristics of this new media in fixed bed biofilm process were investigated. The characteristics of media considered here are a void volume fraction, a specific surface area, and surface characteristics of media. The effect of surface roughness and material could be clearly demonstrated by the fact that the porous glass media showed a good potential for biofilm development. This might results from the fact that biofilm is initially formed in the surface cavities of the media is protect from the shear effect. Therefore, the microcolonies are not readily detached by the fluid shear. In the steady state, biofilm formation along the packing bed depth was different from media to media. The specific area was also an important factor for the attachment of microorganism on the media surface. The specific area was also an important factor for the attachment of microorganism on the media surface. In the case of porous glass media, about $100m^2/m^3$ was enough to obtain a good organic removal efficiency The organic removal efficiency could be improved by increasing the void volume fraction in the reactor, at least 80% was required to obtain a high removal efficiency and prevent clogging. From the analysis of kinetics study, the yield coefficient, Y, was 0.42 mgMLSS/mgSBOD, endogenous respiration coefficient, ke, was $0.12day^{-1}$ and substrate removel coefficient of Mckinney. km, was $16.8hr^{-1}$ for the porous glass media G-2

• Carbon letters
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• 제9권1호
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• pp.23-27
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• 2008

The adsorption and reduction of Cr (VI) to Cr (III) by surface modified activated carbon (AC) in an aqueous solution was studied. The effects of surface modifications on the properties of the carbons were investigated by the analysis of specific surface area, carbon surface pH, acid/base surface values and functional groups. In order to understand the Cr(VI) adsorption and reduction ratio from Cr(VI) to Cr(III), the Cr adsorption capacity of AC was also measured and discussed by using inductively coupled plasma and UV spectrophotometer. The modifications bring about substantial variation in the chemical properties whereas the physical properties such as specific surface area, pore volume and pore size distribution nearly were not changed. Total Cr adsorption efficiency of as-received activated carbon (R-AC) and nitric acid treated activated carbon (N1-AC and N2-AC) were recorded on 98.2, 99.7 and 100%. Cr(III) reduction efficiency of R-AC increased largely from 0.4% to 28.3% compared to N1-AC and N2-AC.

• 대한환경공학회지
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• 제32권12호
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• pp.1147-1153
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• 2010

본 연구에서는 Compound parabolic concentrator reactor system을 이용하여 초기농도 10 mg/L의 클로로포름을 광촉매 반응으로 처리하였다. 1000 W의 메탈할라이드 방전램프를 인공태양광원으로 사용하였으며 약 99%의 클로로포름이 광촉매반응에 의하여 90분 안에 제거되어 먹는물 수질기준인 0.08 mg/L을 만족하였다(pH 5.24, $TiO_2$ 농도 0.2 g/L). 또한 초기 pH와 $TiO_2$ 농도가 클로로포름의 분해에 미치는 영향 을 알아보기 위해 pH 4, 5, 6, 7과 $TiO_2$ 농도 0.1, 0.2, 0.4의 조건에서 실험을 수행하였으며, 각 pH 에서의 $TiO_2$ 입자크기(particle size)와 비표면적(specific surface area)을 측정하여 클로로포름 분해율과 비교하여 비표면적과 광촉매반응 활성 사이의 상관관계를 규명하고자 하였다. 그 결과 pH와$TiO_2$ 농도에 따른 클로로포름 분해율은 큰 차이를 보이지 않았다. 하지만 pH에 따라 $TiO_2$의 입자크기분포(particle distribution)와 비표면적이 변했고 pH 7은 다른 pH 영역보다 비표면적이 약 2배 정도 작은 결과를 보였다. 본 연구의 결과를 바탕으로 클로로포름의 광촉매반응은 $TiO_2$의 비표면적과 상관관계가 없는 TCE-type인 것을 유추할 수 있었다.

• 한국세라믹학회지
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• 제25권3호
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• pp.193-200
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• 1988

침전법에 의해서 pH가 7, 9, 10, 11인 조건에서 생성된 알루미늄 수산화물을 출발물질로 하여 열처리에 따른 알루미나 분말의 특성을 연구하였다. $600^{\circ}C$에서 2시간 동안 열처리하였을 때 비정질 알루미늄 수산화물의 결정수가 탈수된 후에 생성된 최초의 상은 비정질 알루미나의 비표면적은 감소하였다. 비정질 알루미늄 수산화물을 제외한 나머지 알루미늄 수산화물로부터 결정수의 탈수는 비표면적을 증가시켰으며 AlOOH 형태의 수산화물의 존재비가 클수록 전이 알루미나 존재영역까지는 비표면적이 더 크게 나타났다. $\alpha-Al_2O_3$로의 전이속도는 동일온도에서 pH=7 > pH=10 > pH=9 > pH=11의 순서로 일어났으며, 생성된 $\alpha-Al_2O_3$ 분말의 morphology는 알루미늄 수산화물의 외형을 남긴 형골입자(skeleton particle였다. 또한, 열처리 온도의 증가와 $\alpha-Al_2O_3$로의 전이가 일어남에 따라 비표면적의 감소와 더불어 입자성장이 일어나다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.501-504
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• 2003

The purpose of this work is to introduce some fundamental stereological concepts to quantify damage parameters using X-ray CT(Computed Tomography) in the scope of CDM(Continuum Damage Mechanics). X-ray CT is a completely nondestructive technique for visualizing features in the interior of opaque solid objects, and for obtaining digital information on their 3D geometries and properties. Many researchers have introduced lots of damage parameters to model the mechanical behavior of deteriorated materials. Those damage parameters can be represented in many forms such as specific void or crack surfaces, the spacing between cracks, the specific damaged surface area, the specific damaged surface area tensor, the mean solid path among the damaged surfaces and the mean solid path tensor. Despite of many accomplishments in CDM since there is no the systematic experiment, it have limitations in application. In this situation, X-ray computed tomography is highlited by many researchers and applied in a wide range of materials including rock, bone, ceramic, metal, soft tissue and concrete.