• 한국환경과학회지
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• 제8권4호
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• pp.473-477
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• 1999

The purpose of this study was to investigate the characteristics of removal efficiency for aromatic hydrocarbons using a high-temperature fiber filter on a laboratory scale. The main elemental compositions of a high-temperaure fiber filter are aluminium and silica, which can act as the catalysts. Benzene, toluene and o-xylene among aromatic hydrocarbons were used in this experiment. For 3cm thickness of fiber filter, these compounds were removed more than 90% at the face velocities of 3cm/sec and 5cm/sec above 45$0^{\circ}C$. For 4cm thickness of it, the removal efficiencies of these compounds were almost 90% from 40$0^{\circ}C$ at the same face velocities, suggesting that it may be due to increasing the contact time between the fiber filter and aromatic hydrocarbons. The pressure droop ranged from 22 to 48mmH2O for 3cm thickness of fiber filter. However, for 4cm thickness of it, it was about two times(41~89mm$H_2O$) higher than that for 3cm fiber thickness.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권7호
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• pp.41-53
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• 2013

The study is to propose the optimal separation technique of heavy metals (Pb and Zn) contaminated in soil for improving the removal efficiency by various applicable techniques. The heavy metal contaminated soil samples near abandoned mine X-1 and X-2 were used for the study. Firstly, the wet classification process was shown more than 80% of removal efficiency for lead and zinc. Meanwhile, the magnetic separation process was shown low removal efficiency for lead and zincs because those heavy metals were non-magnetic materials. For the next step, the flotation separation process was shown approximately 24.4% of removal efficiency for zinc, while the gravity concentration process was shown approximately 57% of removal efficiency for lead, and 19.9% of removal efficiency for zinc, respectively. Therefore, zinc contaminated in soil would be effectively treated by the combination technique of the wet classification and the flotation technique. Meanwhile, lead contaminated in soil would be effectively treated by the combination technique of the wet classification process and the flotation process. Furthermore, the extraction of organic matter was shown more effective with aeration, 3% of hydrogen peroxide and 3% of lime such as calcium hydroxide.

• 펄프종이기술
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• 제31권2호
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• pp.15-24
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• 1999

A new technique for recycling of white water was developed in order to reduce the calcium hardness in a closed OCC recycling system. Calcium ions present in the white water were precipitated as calcium carbonate by reacting with sodium carbonate, and the precipitated $CaCO_3$ was removed from the system using a flotation fractionation method, which has been commonly used in deinking process. In the flotation stage, a mixed gas of $CO_2$-air was purged into the flotation cell because the pH of $Na_2CO_3$-treated white water was reduced to neutral by $CO_2$ gas. Since $CaCO_3$ precipitate tends to stick onto fine fiber surface and then selectively removed from the white water, a proper amount of suspended solid in white water acts as an important factor for deciding the removal efficiency. By the application of $Na_2CO_3$ addition-$CO_2$ flotation to the short circulated white water, the calcium hardness was significantly reduced by 87% and more. Removal of calcium ions with fine fibers led to a drainage improvement, reduction of fresh water consumption, and enhanced efficiency of wet-end chemicals.

• 한국물환경학회지
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• 제37권4호
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• pp.286-295
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• 2021

The removal efficiency of road-deposited sediment (SDR) by road sweeping was analyzed by performing particle size analysis before and after road sweeping at four highways during May to December 2019. The SDR accounted for the largest proportion in the range of 250 to 850 ㎛ and the degree of its proportion had an effect on the particle size distribution curve. The particle size distribution of the collected sediments showed a similar distribution at all sites. Below 75 ㎛, the removal efficiency of SDR showed a constant value around 40%, but above 75 ㎛, it increased as the particle size increased. The removal efficiency was 82-90% (average 86%) for gravel, 66-93% (average 79%) for coarse sand, 35-92% (average 64%) for fine sand, 29-69% (average 44%) for very fine sand, 19-58% (average 40%) for silt loading, 10-59% (average 40%) for TSP, 13-57% (average 40%) for PM10, and 15-61% (average 38%) for PM2.5. SDR removal efficiency showed an average of 69% for the four highways. It was found that if the amount of SDR was less than 100 g/m², it was affected by the road surface condition and had a large regional deviation. As such, the amount of SDR and the removal efficiency increased. The fine particles, which have relatively low removal efficiency, contained a large amount of pollutants, which is an important factor in water and air pollution. Therefore, various measures to improve the removal efficiency of fine particles in SDR by road sweeping are needed.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.516-522
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• 2023

The co-precipitation process plays a key role in the decontamination of radionuclides from low and intermediate levels of liquid waste. For that reason, the removal of Cs ions from waste solution by the co-precipitation method was carried out. A simulated liquid waste (¹³³Cs) was prepared from a 0.1 M CsCl solution, while wastewater generated by washing steel ash served as a representative of radioactive cesium solution (¹³⁷Cs). By co-precipitation, potassium ferrocyanide was applied for the adsorption of Cs ions, while nickel nitrate and iron sulfate were selected for supporting the precipitation. The amount of residual Cs ions in the CsCl solution after precipitation and filtration was determined by ICP-OES, while the radioactivity of ¹³⁷Cs was measured using a gamma-ray spectrometer. After cesium removal, the amount of cesium appearing in both XRD and SEM-EDS was analyzed. The removal efficiency of ¹³³Cs was 60.21% and 51.86% for nickel nitrate and iron sulfate, respectively. For the ash-washing solution, the removal efficiency of ¹³⁷Cs was revealed to be more than 99.91% by both chemical agents. This implied that the co-precipitation process is an excellent strategy for the effective removal of radioactive cesium in waste solution treatment.

• 멤브레인
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• 제30권4호
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• pp.269-275
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• 2020

본 연구에서는 세라믹 중공사 접촉막 모듈을 이용하여 CH₄/CO₂ 혼합가스에서 CO₂ 분리 실험을 수행하였다. 높은 성능의 접촉막 모듈을 제작하기 위해 고투과성 중공사막의 제조 실험을 진행하였으며, 제조한 중공사막은 N₂ 기체투과실험을 통해 투과 성능을 평가하였다. 최종적으로 고투과도 중공사막을 이용하여 CH₄/CO₂ 혼합 기체 분리를 위한 Hollow fiber membrane contactor (HFMC)를 제작하였다. 실험에는 CH₄/CO₂ 혼합 기체(34.5% CO₂, CH₄ balance)와 monoethanolamine (MEA)를 사용하였으며, CO₂ 제거 효율이 흡수제의 유량에 따라 어떠한 영향을 받는지 평가하였다. CO₂ 제거 효율은 액체유량이 증가함에 따라 같이 상승하였으며, CO₂ 흡수 flux 또한 액체유량과 함께 증가하는 결과를 보였다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Proceedings of Pre-symposium of the 10th ISWPC
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• pp.164-171
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• 1999

A new technique for recycling process water was developed in order to reduce the calcium hardness of the closed OCC recycling system. Calcium ions present in the white water were precipitated as calcium carbonate by a reaction with sodium carbonate and the CaCO$_3$precipitates were easily removed from the system by a dissolved air flotation(DAF) method. After the DAF stage, CO$_2$-gas was purged into the water because the pH of Na$_2$CO$_3$-treated white water was reduced to neutral by CO$_2$gas. Since CaCO$_3$precipitate tends to stick onto the fine fiber surface and then is selectively removed from the water, a proper amount of suspended solid in the process water acts as an important factor in deciding the removal efficiency. By the application of Na$_2$CO$_3$addition - DAF - CO$_2$purging to the short circulated white water the calcium hardness was significantly reduced by 92% and more. The removal of calcium ions with fine fibers led to drainage improvement, reduction of fresh water consumption, and enhanced efficiency of wet-end chemicals.

• 반도체디스플레이기술학회지
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• 제16권2호
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• pp.55-60
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• 2017

The supercritical $CO_2$ (sc-$CO_2$) mixture and the sc-$CO_2$-based Photoresist(PR) stripping(SCPS) process were applied to the removal of the post etch/ash PR residue on aluminum patterned wafers and the results were observed by scanning of electron microscope(SEM). In the case of MDII wafers, the carbonized PR was able to be effectively removed without pre-stripping by oxygen plasma ashing by using sc-$CO_2$ mixture containing the optimum formulated additives at the proper pressure and temperature, and the same result was also able to be obtained in the case of HDII wafer. It was found that the efficiency of SCPS of ion implanted wafer improved as the temperature of SCPS was high, so a very large amount of MEA in the sc-$CO_2$ mixture could be reduced if the temperature could be increased at condition that a process permits, and the ion implanted photoresist(IIP) on the wafer was able to be removed completely without pre-treatment of plasma ashing by using the only 1 step SCPS process. By using SCPS process, PR polymers formed on sidewalls of metal conductive layers such as aluminum films, titanium and titanium nitride films by dry etching and ashing processes were removed effectively with the minimization of the corrosion of the metal conductive layers.

• 청정기술
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• 제29권4호
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• pp.313-320
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• 2023

대표적인 비암모니아성 선택적 촉매환원반응기인 H₂-SCR의 활용성을 높이기 위하여 Ce를 조촉매로 활용한 PtNi/CeO₂-W-TiO₂의 촉매 분말을 합성하고 다공성 금속 구조(porous metal structure, PMS)에 코팅하여 선택적 촉매 환원에 의한 NOx 제거 특성을 평가하였다. CeO₂를 조촉매로 사용한 H₂-SCR은 CeO₂를 사용하지 않은 경우에 비해 더 높은 NOx 제거 효율을 나타내었으며, CeO₂ 담지율 10 wt%에서는 반응온도 90℃에서 가장 높은 제거효율을 보였다. 한편, 촉매구조체인 PMS의 촉매 코팅량이 증가함에 따라 NOx 제거효율은 90℃ 이하에서는 향상되었으나, 120℃ 이상에서는 감소하는 경향을 보였고 공간속도를 4,000 h^-1에서 20,000 h^-1로 변경한 경우, 120℃이상의 온도에서 NOx 제거 효율이 향상되는 것을 확인할 수 있었다.

• 한국대기환경학회지
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• 제14권5호
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• pp.455-464
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• 1998

Removal teals of Soxmox were performed using low density ceramic filters doped with various catalysts. Disc type (50 mmO.Dx10 mmt) low density ceramic filters were doped with three different catalysts such as Cu to remove SOx and NOx, and Mn and Co to remove NOx. The air permeabilities and specific surface areas were 40~50cc/min.cm2.cmH2O and 4.1~8.88 m2/g, respectively. Also, the peak pore sizes of catalyst support were 3~5nm. Tests were focused to search optimum operating temperatures for different catalysts. It was found that as the CuO content increases, SOx removal efficiency was increased. NOx removal efficiencies for Mn, Cu and Co, were 85% at 30$0^{\circ}C$, 90% at 40$0^{\circ}C$ and 90% at 45$0^{\circ}C$, respectively.