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고분자 전해질 막 연료전지(PEMFC)의 백금 나노 입자 및 분자 구성요소간 상호작용 연구
권성현,이지혜,장승순,이승걸 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
고분자전해질 연료전지(PEMFC)는 수소와 산소를 에너지원으로 사용하며 높은 에너지 효율로 인해 친환경적 에너지 시스템으로 연구되고 있다. 특히, 연료전지의 구성요소 중 하나인 막 전극 접합체(MEA)는 지지층, 촉매층 고분자와 같이 구성요소가 다양하며 이에 따라 다양한 계면을 형성하고 있다. 본 연구는, 분자동역학(MD) 이론 및 양자역학 기반의 밀도범함수이론(DFT)을 사용한 멀티 스케일적 접근 방법을 통해 연료전지의 삼상계면 시스템에 대한 시뮬레이션을 진행하였다. 특히 분산력이 고려된 밀도범함수이론을 사용하여 백금 및 구성분자들간 거리에 따른 상호작용에 대해 계산하고, 분자동역학용 백금-분자간 비결합 상호작용에 필요한 힘장을 개발하였다. 개발된 힘장을 기반으로 분자동역학을 이용하여 나피온 -Pt-탄소(흑연)의 삼상계면 시스템의 모델링 및 수송 특성에 대한 연구를 진행하였다. <sup>**</sup>This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2015M1A2A2057129).
밀도범함수이론을 통한 MgO의 CO<sub>2</sub> 흡착효율 향상을 위한 담지체 후보군의 열역학적 물성 연구
권성현,이지혜,이승걸 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
화석연료의 연소로 인한 다량의 이산화탄소 배출은 심각한 지구 기후변화를 유발하게 된다. 따라서 공장 연도에서 배출되는 이산화탄소를 직접적으로 흡착할 수 있는 흡착제에 대한 연구가 활발하게 진행되고 있다. 특히, 이산화탄소 흡착 가능 물질인MgO는 금속산화물 중 하나로 이산화탄소 흡착용량이 높으며 발전소에서 사용되는 흡착 공정에 적용하기에 적합한 흡착온도를 가지고 있다. 하지만, 실제 흡착공정에서 단일 MgO의 사용은 낮은 반응속도 및 MgO간 응집 현상으로 인해 이론 흡착량에 비해 낮은 이산화탄소 흡착량을 보이고 있다. 이러한 MgO의 단점을 해결하기 위해 MgO에 과량의 Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, SiO<sub>2</sub>와 같은 담지체를 사용하여 MgO의 열적 안정성, 기계적 강도, 일정한 표면적을 확보하려는 연구가 진행되고 있다. 본 연구에서는 밀도범함수이론 및 포논 계산을 통해 흡착 온도의 증감에 따른 MgO 및 각 담체 간의 열역학적 특성을 계산하였다. <sup>**</sup>This work was supported by KCRC through the NRF funded by Ministry of Science, ICT, and Future Planning (NRF-2015M1A8A1048902).
A comparative, kinetic study on cork and activated carbon biofilters for VOC degradation
권성현,Daechul Cho 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.1
Two bio-filters packed with cork, an organic macroporous material and activated carbon, an inorganic microporous one were compared in terms of operative performance on biological degradation of VOC, which was a mixture of benzene, toluene, ethylbenzene and xylene (BTEX) vapors. Two filters were successfully operated for 4 months with three different periods. In general, the bio-filter with packed cork in the long thin glass was distinguishably better than the one with biological activated carbon (BAC). During the first period in which 150 ppm of the gas was flown in at 90 s of empty bed retention time (EBRT), the cork bio-filter performed better except for the first 2 weeks, the biological adaptation phase, which provided the BAC bio-filter with its much greater adsorption capacity as to lead to nearly perfect removal. Despite the shorter breakthrough point for cork, however, the cork bio-filter overwhelmed the BAC after that; even three times higher BTEX load at the shorter EBRT guaranteed the cork filter 90% or more removal. The maximum elimination capacities were 86 g/(m3 h) for the cork and 67 g/(m3 h) for the BAC around 94 g/(m3 h) of inlet load. The higher biomass in the cork column could be resulted from organic surfaces, pore structure with sufficient room for soundmicrobial filmor clumps even though its specific surface area was only 1/12 of BAC. This finding was supported by the model calculation in which the effective surface area of cork bed turned out to be 33% more than that of BAC. The derived relationship between consumption of BTEX and growing cell mass was found to be logarithmically proportional to each other, which was confirmed experimentally in here. We also found that through one-third of the whole length of the packed columns, as much as 79% of the inlet concentration of BTEX gas in the cork bio-filter was eliminated, which well agreed to our data and model depicting concentration versus column height, showing 1st order gradient.
권성현,조대철 한국산학기술학회 2002 한국산학기술학회논문지 Vol.3 No.4
본 연구는 천연계 계면활성제의 하나인 사이클로덱스트린을 이용한 화학적 토양세정을 다룬다. 두가지 polycyclic aromatic hydrocarbon인 phenanthrene과 naphthalene을 오염물질로 선정하고 토양종류 및 세정강도를 주변수로 하여 수직칼럼 상에서의 오염물질 제거효과를 분석, 고찰하였다. 실험실 규모의 연구결과, 오염원 제거효율은 세정액의 유량, 농도, 온도 및 토양칼럼의 공극률에 비례하는 것으로 나타났으며, 형광광도 분석과 methylene blue와 같은 염료 라벨링 분석을 통하여 초기 세정은 토양과 계면활성제의 흡착에 의존하고 세정이 거듭될수록 유체흐름에 의한 전단력이 주요변수임을 확인할 수 있었다. 본 데이터는 향후 pilot 규모의 현장세정시 기초자료로 활용가능하며, 세정전략(회분식, 연속식) 수립에 유용할 것으로사료된다. PAHs (polycyclic aromatic hydrocarbons) deposited in soil are one of serious problems against sustainable land use. In this paper, chemical soil flushing in a packed sandy soil matrix using a natural surfactant, β-cyclodextrin (CD) was studied via a fluorescence spectroscopy and a dye labelling. The contaminants are lipophilic ring compounds - phenanthrene and naphthalene. Sand type and flushing intensity (rate and concentration) are chosen as important investigation variables. The removal efficiencies were proportional to flow rate, concentration, temperature of the flushing solution and voidity of the sand column. Initial sorption of the surfactant onto the soil matrix was found to be a key step while flow shear was more crucial in the latter steps. The residual portion of the surfactant, which was most likely to be due to the initial sorption, would not be so influential on this type of soil washing for long times. These results will be useful in future for pilot scale in situ washing and for establishing better soil washing strategy.
Bioremediation of Aroclor 1242 by a Consortium Culture in Marine Sediment Microcosm
권성현,홍명현,최정혜,황경숙,이한석,소재성,고성철 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.6
Plant terpenes have proven to be effective in stimulation of polychlorinated biphenyls (PCBs) biodegradation in soil systems. However, data on the application of plant terpenes in marine sediments contaminated with PCBs remains limited. The aim of this study was to ascertain the roles of a PCB degrading consortium and plant terpenes in stimulation of PCB biodegradation in marine sediments. The consortium culture 1-2Mix (strains 1-2M and 1-2T in commensalism), a utilizer of biphenyl and a natural substrate was enriched and isolated from marine sediments from the Busan coast, South Korea. PCB degradation by this culture was shown to be more effectively induced by tangerine peel extract than other known substrates (limonene, pinene, and cymene). Coastal sediment microcosms inoculated with 1-2Mix were set up to elucidate the effect of the consortium and plant terpenes on degradation of Aroclor 1242. After four weeks, the highest removal rates of PCBs, compared with the control (autoclaved sediment and no inoculation of 1-2Mix), were observed in order of the inducers tested; biphenyl (71.1%), tangerine peel extract (69.5%), surfactant (66.0%), and limonene (63.0%). Bioaugmentation effect was doubled in the presence of natural substrates such as tangerine peel extract and limonene, indicating effectiveness of these substrates in biostimulation. It was concluded that the tangerine peel extract could replace biphenyl as a feasible induction substrate for effective remediation of PCBs in the marine sediment.