• Carbon letters
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• 제2권1호
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• pp.44-54
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• 2001

The characteristics of adsorption and desorption of benzene and toluene were investigated at a fixed bed packed with the activated carbon and activated carbon fiber. Through breakthrough experiments under various feed concentration conditions, it was found that the slope of mass transfer zone and the tailing in the breakthrough curves were different from the feed conditions due to different heats of adsorption. In hot nitrogen desorption, the regeneration time and mass transfer zone of the toluene desorption curve were longer than those of the benzene desorption curve because of the difference in adsorption affinity. With an increase in the regeneration temperature, the height of roll-up and the sharpness of desorption curves increased but the regeneration times decreased. The adsorption capacities of the activated carbon and activated carbon fiber after three-time thermal regenerations decreased about 25% and 37% for benzene and 18% and 25% for toluene, respectively. To investigate the effect of the regeneration temperature on the energetic efficiency, the characteristic desorption temperatures of toluene and benzene were investigated by calculating purge gas consumption and temperature.

• Environmental Engineering Research
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• 제22권2호
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• pp.169-174
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• 2017

Vacuum swing adsorption (VSA) is a promising treatment method for volatile organic compounds (VOCs). This study focuses on a VSA process for regenerating activated carbon spent with VOCs, and then investigates its adsorption capacities. Toluene was selected as the test VOC molecule, and the VSA regeneration experiments results were compared to the thermal swing adsorption process. Cyclic adsorption-desorption experiments were performed using a lab-scale apparatus with commercial activated carbon (Samchully Co.). The VSA regeneration was performed in air (0.5 L/min) at 363.15 K and 13,332 Pa. The comparative results depicted that in terms of VSA regeneration, it was found that after the fifth regeneration, about a 90% regeneration ratio was maintained. These experiments thus confirm that the VSA regeneration process has good recovery while operating at low temperatures (363.15 K) and 13,332 Pa.

• Bulletin of the Korean Chemical Society
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• 제20권12호
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• pp.1447-1450
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• 1999

Countercurrent oxygen reaction (COR) was developed and evaluated for regeneration of exhausted activated carbon. Whether the regeneration technique is feasible or not is affected strongly by gradual loss and physical changes of activated carbon, energy consumption, and effective removal of adsorbed materials during the process. Various parameters such as reaction temperature, the loss of activated carbon, surface area, pore volume, surface structure, adsorptive property, etc. were examined to determine the effectiveness of COR. The results of these tests showed that the parameters were strongly dependent on oxidant flow rate, and suggest that the newly developed COR is comparable and, in some ways, possibly superior to conventional regeneration techniques because the overall process runs in a single step and is less energy intensive, and also because the adsorptive capacity of exhausted activated carbon was completely recovered.

• 한국안전학회지
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• 제7권1호
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• pp.13-19
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• 1992

Supercritical fluid technology was applied to the regeneration of industrial catalyst contaminated with toxic materials. The regeneration process of activated loaded with phenol was proposed, then the adsorphon tower was packed with the activated carbon-bed. Phenol diffuses into supercritical carbon dioxide(SCC) through the micro-pore and voldge of the activated carbon. The saturated solubility of phenol in SCC depended on the density of SCC varing with temperature and pressure conditions. Therefore, the fasile phase equilibrium calculation model of dxpanded liquid One was proposed, and equilibrium solubility of phenol in SCC was calculated using the model theoretically. The regeneration mechanism of activated carbon was analysed by degree of saturation of phenol and diffusion in SCC. The solubility prediction was more satisfactory for the wide range of SCC density than the dense gas model and the desorption of phenol depended on the degree of saturation of phenol in SCC.

• Carbon letters
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• 제11권1호
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• pp.13-21
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• 2010

Coconut shell activated carbon (CSAC) was investigated for its ability in the removal of two neutral chlorinated organic compounds, namely trichloroethylene (TCE) and dichloromethane (DCM) from aqueous solution using a packed bed column. The efficiency of the prepared activated carbon was also compared with a commercial activated carbon (CAC). The important design parameters such as flow rate and bed height were studied. In all the cases the lowest flow rate (5 mL/min) and the highest bed height (25 cm) resulted in maximum uptake and per cent removal. The experimental data were analysed using bed depth service time model (BDST) and Thomas model. The regeneration experiments including about five adsorption-desorption cycles were conducted. The suitable elutant selected from batch regeneration experiments (25% isopropyl alcohol) was used to desorb the loaded activated carbon in each cycle.

• 한국환경과학회지
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• 제17권5호
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• pp.493-500
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• 2008

This paper describes the adsorption/desorpton efficiency of a modified activated carbon by irradiated microwave to treat toluene. By employing microwave energy, the regeneration time was considerably shortened compared with conventional thermal heating regeneration. New adsorbent called ACB (Activated Carbon-Bentonite) was prepared from powder activated carbon with mixing bentonite as a binder. Specific surface area, average pore size and total pore volume of ACB were calculated from the nitrogen adsorption/desorption isotherm. The surface of ACB was characterized with scanning electron microscope(SEM). The results showed that the specific surface area, total pore volume, average pore size of ABC was not influenced by regenerating cycle with microwave irradiation. Toluene was adsorbed onto ACB which desorbed by MW irradiation. Absorption capacity of ACB was 0.117 $g_{toluene}/g_{ACB}$. Desorption efficiency of toluene increased as higher microwave output was applied.

• Korean Chemical Engineering Research
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• 제43권3호
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• pp.432-437
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• 2005

혼합가스로부터 $CO_2$를 분리, 회수하기 위하여 활성탄소섬유를 흡착제로 사용한 전기변동흡착(electric swing adsorption, ESA) 공정의 타당성을 검토하였다. 활성탄소 섬유는 상압에서도 $CO_2$에 대해 빠른 흡착 속도를 보였으며, 비교적 짧은 흡착대와 긴 파과시간, 흡착제의 단위무게당 높은 흡착량을 나타내었다. 포화흡착된 흡착탑의 재생에서 비표면적이 큰 활성탄소섬유일수록 일정한 모양의 파과곡선을 유지하여 흡착-탈착의 재생사이클에 유리하였다. 진공탈착에 의한 흡착탑의 재생률은 64 cmHg의 압력에서도 64％ 이상이었고, 전기탈착을 병행한 hybrid 재생단계에서는 17％의 추가적인 재생률을 보이며 7-8 Wh의 낮은 재생에너지에서도 높은 재생률을 보였다.

• 공업화학
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• 제8권5호
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• pp.737-741
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• 1997

휘발성 유기용제의 주된 제거방법은 흡착제를 이용한 흡착 공정이 추천된다. 본 연구에서는 입상활성탄과 활성탄소섬유에 휘발성 유기용제를 흡착시킨 후 폐흡착제를 탈착컬럼에 넣고 318.15 K의 온도에서 압력을 변수(2000~3000 psi)로 하는 초임계 이산화탄소를 이용하여 재생하였다. 초임계 이산화탄소의 압력이 증가함에 따라 탈착율과 요오드 흡착가는 증가하였으며, 재생시간은 MEK와 benzene의 경우 각각 70분과 60분이었다. 최대 탈착율은 3000psi의 압력에서 MEK가 흡착된 입상활성탄과 활성탄소섬유의 경우 각각 초기 흡착량의 64.0%, 55.3%가 탈착되었으며, 벤젠이 흡착된 입상활성탄과 활성탄소섬유의 경우에는 각각 59.1%, 45.2%가 탈착되었다. 또한 Tan과 Liou의 모델로 출구농도를 예측할 수 있었다. 따라서 입상활성탄뿐만 아니라 활성탄소섬유의 재생공정에도 초임계유체 재생법의 적응 가능성을 확인할 수 있었다.

• 상하수도학회지
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• 제23권4호
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• pp.407-416
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• 2009

The objective of this study was to evaluate the variation of physical properties and adsorption capacity after regeneration of Granular Activated Carbon (GAC). It was found that the loss rate of regenerated carbon was related to the usage time of GAC. The correlations between iodide number and loss rate also determined. Effective size and uniformity coefficient for regenerated GAC were within a similar range compared to virgin GAC. This result indicated that the function as media is recovered. Although iodide number and specific surface area for regenerated GAC were not completely recovered compared to that of virgin GAC, cumulative pore volumes of regenerated GAC were increased. Removal efficiency of organic matter in regenerated GAC was resulted the same or slightly higher than that of virgin GAC. This result indicates that the number of mesopore responsible for removal of organic matter was increased after regeneration.

• 공업화학
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• 제31권3호
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• pp.341-345
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• 2020

하폐수처리 및 정수처리에 사용되는 활성탄 흡착 공정에서 기존의 활성탄 열재생법 비해 활성탄 손실과 불완전 연소로 인한 오염물질 발생도 적으며, 사용 활성탄의 인발-재생-재충진에 소요되는 시간의 절약이 가능한 재생 방법으로 오존수를 이용한 in situ regeneration에 대한 기초연구를 수행하였다. 활성탄 흡착 컬럼 상에서 페놀(phenol) 및 PEG를 흡착 파과 시킨 후 오존수 접촉으로 흡착물질을 분해 제거하는 흡착-재생 싸이클을 반복하였다. 오존수 접촉에 의한 재생 횟수가 증가할수록 페놀 흡착용량은 어느 정도 감소하지만, 일정 수준으로의 감소 후에는 구조 변화가 안정화되어 추가적인 감소가 일어나지 않았다. 흡착 용량이 감소하는 이유는 오존과의 반응에 의해 활성탄의 미세공 크기가 증가하면서 비표면적이 감소하기 때문으로 나타났다. 이러한 세공 크기의 변화와 비표면적의 변화로 인하여 재생 후 in-pore adsorption이 우세한 페놀과 같은 저분자량 물질의 흡착효율은 감소하게 되나 external adsorption 비율이 큰 PEG와 같은 고분자량 물질의 흡착효율은 크게 영향을 받지 않았다. 세공 크기 및 비표면적의 변화는 오존수와의 접촉시간이 길어질수록 심화되므로 제거하려는 물질의 크기를 고려하고 접촉시간을 조절함으로써 흡착 효율의 유지를 제어하는 것이 필요하다.