• Korean Chemical Engineering Research
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• 제60권3호
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• pp.377-385
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• 2022

우리나라 전통 숯가마로부터 제조된 숯의 표면형상과 흡착특성을 분석한 후, 습도와 온도를 조절하면서 이들의 수분 흡착성능을 측정하고 황토, 활성탄소섬유 직포 및 활성탄소섬유 종이의 수분 흡착성능과 비교하였다. 숯은 소수성이므로 45% 이하의 습도에서는 수분을 잘 흡착하지 않지만 습도가 증가하면 흡착성능이 서서히 1차식에 비례하여 증가하였다. 황토 분말도 낮은 습도에서는 숯과 유사했지만 습도가 증가하면 흡착성능이 기하급수적으로 증가하면서 Type V 등온흡착곡선을 보였다. 따라서 조선시대에 기상청 직원들이 숯과 황토의 수분 흡착능력을 일기예보에 적용하였다는 기록을 실험적으로 확인할 수 있었다. 활성탄소섬유 직포와 활성탄소섬유 종이는 수분 흡착능력이 월등하고 신속한 반응을 보이므로 습도측정 센서에 적용할 수 있다고 판단된다. 숯 조각의 등온흡착 및 탈착곡선 측정에서 흡착질인 질소의 탈착이 잘 이루어지지 않아 낮은 압력 이력현상(low-pressure hysteresis)이라는 독특한 Type I과 Type IV의 혼합형태를 보이는데, 이는 질소입자가 흡착시에 숯 세공의 틈새를 비비고 들어가 단단히 끼었다가 탈착시에 빠져나오지 않기 때문이다. 숯을 분말로 분쇄하면 이러한 틈새들이 분쇄되어 비표면적이 증가하고 낮은 상대압력에서 흡착질의 탈착량이 증가되었다.

• Carbon letters
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• 제7권2호
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• pp.105-113
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• 2006

The electro-chemical removal (ECR) of water pollutants by metal-ACF electrodes from wastewater was investigated over wide range of ECR time. The ECR capacities of metallic ACF electrodes were related to physical properties such as adsorption isotherm, surface area and pore size and to reaction time. Surface morphologies and elemental analysis for the metal supported ACFs after electro-catalytic reaction were investigated by scanning electron microscopy (SEM) and energy disperse X-ray (EDX) to explain the changes in adsorption properties. The IR spectra of metallic ACFs for the investigation of functional groups show that the electro-catalytic treatment is consequently associated with the removal of pollutants with the increasing surface reactivity of the activated carbon fibers. The metal-ACFs were electro-catalytically reacted to waste water to investigate the removal efficiency for the COD, T-N, $NH_4$-N, $NO_3$-N and $NO_2$-N. From these removal results of the piggery waste using metallic ACFs substrate, satisfactory removal performance was achieved. The removal efficiency of the metallic ACFs substrate was mainly determined by the properties of the material for adsorption and trapping of organics, and catalytic effects.

• Carbon letters
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• 제27권
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• pp.64-71
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• 2018

$TiO_2$-doped activated carbon fibers (ACFs) were successfully prepared as capacitive deionization (CDI) electrode materials by facile ultrasonication-assisted process. ACFs were treated with titanium isopropoxide (TTIP) and isopropyl alcohol solutions of different concentrations and then calcinated by ultrasonication without heat-treatment. The results show that a certain amount of anatase $TiO_2$ was present on the ACF surface. The specific capacitance of the $TiO_2$-doped ACF electrode was remarkably improved (by 93.8% at scan rate of $50mV\;s^{-1}$) over that of the untreated ACF electrode, despite decreases in the specific surface area and total pore volume upon $TiO_2$ doping. From the CDI experiments, the salt adsorption capacity and charge efficiency of the sample with TTIP percent concentration of 15% were found to considerably increase by 71.9 and 57.1%, respectively. These increases are attributed to the improved wettability of the electrode, which increases the number of surface active sites and facilitates salt ion diffusion in the ACF pores. Additionally, the Ti-OH groups of $TiO_2$ act as electrosorption sites, which increases the electrosorption capacity.

• 대한환경공학회지
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• 제31권11호
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• pp.1025-1032
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• 2009

본 연구에서는 세탁소에서 배출되는 휘발성유기화합물을 흡착처리하는 공정의 개발 가능성을 검토하였다. 휘발성 유기화합물을 흡착하는 재료로는 핏치계 활성탄소섬유를 선택하였고, 흡착제의 재생방법으로는 전기변동법을 사용하였다. 용제는 트리클로로에틸렌과 톨루엔을 대상으로 하였으며 활성탄소섬유와 용제의 종류에 따른 파과곡선과 흡착량을 비교 검토하였다. 흡착량을 증대시키기 위하여 다양한 방법으로 활성탄소섬유를 전처리하였다. 또한 흡착이 완료된 활성탄소섬유의 재생에 필요한 온도와 허용전압을 측정하였다. 그 결과 트리클로로에틸렌의 흡착에는 미세 기공이 잘 발달된 활성탄소섬유가 우수한 성능을 나타낸 반면 톨루엔의 경우에는 비표면적이 큰 흡착제가 우수한 성능을 보였다. 활성탄소섬유는 흡착제 무게의 41~54%에 해당하는 트리클로로에틸렌을 흡착하였으며 유입되는 휘발성유기화합물의 농도가 높아지면 완전흡착시간은 급격히 짧아지고 흡착량은 서서히 감소하여 낮은 농도의 휘발성유기화합물을 처리하는 것이 보다 유리한 것으로 나타났다. 활성탄소섬유 표면의 산소작용기를 조절한 결과, 진공열처리를 한 활성탄소섬유의 톨루엔 흡착성능이 가장 우수한 것으로 나타나, 톨루엔의 흡착은 빈자리 탄소(vacant carbon site)가 흡착점이라고 판단된다. 흡착된 용제는 $150^{\circ}C$에서 대부분 탈착되었다.

• 한국안전학회지
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• 제36권1호
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• pp.80-85
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• 2021

Radionuclides, particularly radioactive cesium (Cs), are a concern of human health in some nuclear power accidents. It could lead to a high level of intracellular accumulation due to its high radioactivity and long half-life. Therefore, it is imperative to develop a method to remove Cs from wastewater. Herein, we synthesized activated carbon fibers (ACFs) doped with Prussian blue (PB) via in situ methods. We classified samples by their preparation method as either physical (PB-ACF-A) or physicochemical (PB-ACF-B) syntheses for comparison. The PB-ACF-B sample showed a significant surface loss compared to PB-ACF-A but a better ¹³³Cs adsorption capacity. All samples fit well to Langmuir isotherms and the values of qmax were directly correlated to the amount of PB on the surface of the ACFs. Adsorption characteristics were further confirmed by the calculated free energy, enthalpy, and entropy.

• 상하수도학회지
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• 제14권1호
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• pp.84-98
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• 2000

Control of Trihalomethanes(THMs) is a major concern of many water treatment plants. A number of researchers have studied the effectiveness of activated carbon adsorption process in removing THMs or organic halogen compounds. Recently, attention has been paid to the biological activated carbon (BAC) treatment of THM precursors as an alternative to the carbon adsorption treatment because of its effectiveness as well as its low running cost. In this study, changes of THM formation potential(THMFP) and removal of substrates in the SBR effluent were investigated in an attempt to clarify the mechanisms of the decrease/increase of THMFP in the BAC treatment. The increase and decrease of THMFP concentrations were observed in effluents during prolonged operation. When PCP or DBS was feeded as substrate contained in SBR effluent, the THMFPs were easyly removed with TOCs removal. But the case of SBR effluent containing SDS or glycine was introduced, and when microbial growth came to its near steady state, the THMFPs of treated effluents were increased more or less in comparison to those in the influents. Such increases of THMFP coincided with the increase in microbial growth within the activated carbon fiber(ACF) column. In the case of only sucrose was feeded as substrate on ACF colume, THMFP concentrations of effluent were higher than those of influent. The THMFP concentration was significantly increased on inlet part of ACF column, which biomass inhabits abundantly, then they were decreased gradually. These increases mean production of the secondary THM precursors by biological activities, which can be removed by adsorption and biological degradation on ACF column.

• 대한환경공학회지
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• 제27권6호
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• pp.614-619
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• 2005

[ $CO_2$ ]와 $CH_4$의 혼합가스로부터 $CO_2$를 선택적으로 분리, 회수하기 위하여 비표면적과 기공구조가 다른 일련의 활성탄소섬유에 벤젠을 CVD하여 기공 크기를 조절하였다. 벤젠 증착 온도 및 증착 시간을 변화시켜 제조한 ACF 분자체의 흡착 선택도를 $CO_2$와 $CH_4$의 흡착을 통해 측정하였으며, 그 기공구조를 질소흡착에 의한 흡착등온선으로부터 조사하였다. 열분해로 생성된 탄소는 활성탄소 섬유의 기공 크기를 크게 변화시켰으며, 벤젠 CVD에 의해 제조된 ACF 분자체는 $CH_4$의 흡착량을 크게 감소시키며 $CO_2$에 대해 우수한 흡착선택도를 보여주었다.

• Korean Chemical Engineering Research
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• 제52권6호
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• pp.775-780
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• 2014

Micellar enhanced ultrafiltration (MEUF) was used to remove cadmium from an aqueous solution using sodium dodecyl sulfate (SDS) as a surfactant. Operational parameters such as initial permeate flux, retentate pressure, initial cadmium concentration, pH solution, molecular weight cut-off (MWCO), and molar ratio of cadmium to SDS were investigated. Removal efficiency of cadmium from an aqueous solution increased with an increase of retentate pressure, pH solution and molar ratio of cadmium to SDS, and decreased with an increase of initial permeate flux. Higher removal efficiency of cadmium from the aqueous solution was achieved using lower MWCO (smaller membrane pore size). Under optimized experimental condition, cadmium removal efficiency reached 74.6 % within an hour. Using MEUF-ACF hybrid process the removal efficiency of both cadmium and SDS was found to be over 90%.

• 대한환경공학회지
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• 제29권12호
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• pp.1329-1336
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• 2007

본 연구에서는 간헐적으로 발생되는 고농도의 NO를 효율적으로 제거할 수 있는 혼합 공정으로 선택적촉매환원(Selective Catalytic Reduction, SCR)과 활성탄소섬유(Activated Carbon Fiber, ACF)흡착이 결합된 신 개념의 공정을 설계하고 특성을 고찰하였다. NO를 흡착한 ACF에 열과 진공을 동시에 가하여 재생 실험을 수행한 결과, $140^{\circ}C$에서 600 mmHg의 진공으로 탈착하였을 때 가장 높은 재생효율을 보였다. SCR공정에는 상용촉매를 사용하였으며, 반응온도 $300^{\circ}C$, $NO/NH_3$몰비 1.0인 조건에서 실험을 수행하였다. ACF 재생공정에서 발생한 NO를 SCR공정으로 처리하였을 경우 98%의 매우 우수한 제거효율을 보였다. 그러나 지속적으로 유입되는 300ppm의 NO와 ACF에서 탈착되는 NO를 기존의 SCR공정에서 동시에 처리하였을 때 약 1분간 고농도의 NO가 배출되었다. 따라서 ACF의 재생시 발생하는 고농도의 NO를 기존의 SCR공정에서 병행처리할 때는 탈착속도를 조절하거나 고농도로 배출되는 짧은 시간 동안 $NH_3$농도를 높여서 주입할 필요가 있으며, 소규모의 SCR공정을 추가로 설치하여야 한다. SCR과 ACF를 결합한 공정을 이용하여 NO를 처리하였을 때, 간헐적으로 2배의 농도를 가지는 NO가 유입되어도 80% 이상의 탈질 효율을 가지는 공정의 구현이 가능하였으며, 반복 사용에도 활성이 유지되어 안정적인 운전이 가능함을 입증하였다.

• 한국재료학회지
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• 제13권11호
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• pp.749-755
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• 2003

A development of micropores of $CO_2$activated isotropic carbon fibers from TEM was observed. It was observed that the micropores of activated carbon fibers(ACFs) were consisted of slit-shaped pores(SP) and cylinder-shaped pores(CP). The SPs were formed between two parallel-carbon layers, and the CPs were formed at a place which is connected polygonally by more than two carbon layers. It was shown that the CPs of the ACFs were developed at high degree of burn-offs and at high activation temperature. The pore size distribution of the best ACF, which was observed at a highest value of specific surface area(3,495 $\m^2$/g), showed a continuous distribution in the range of about $4∼l5\AA$, and the median pore size was 6.7$\AA$. The super-high specific surface area of ACFs was found to be due to that the SPs were connected with a maximum size of 7∼8$\AA$ continuously, It is possible that the SPs should be formed in the ACFs in order to show super-high SSA.