• Korean Chemical Engineering Research
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• 제53권6호
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• pp.690-694
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• 2015

최근에 직접 액체 연료전지 중에서 직접 개미산 연료전지(Direct Formic Acid Fuel Cells, DFAFC)가 활발히 연구되고 있다. 불소계막을 대신할 저가의 탄화수소막이 DFAFC막으로 주목받고 있다. 본 연구에서는 sulfonated poly(ether ether ketone ketone, sPEEK)막과 Poly(arylene ether sulfone)(PAES)막을 사용해 Nafion 막과 그 특성을 DFAFC 조건에서 비교하였다. 탄화수소계막의 개미산 투과 전류밀도가 $240{\sim}250mA/cm^2$로 불소계인 Nafion 211 막의 $600mA/cm^2$보다 낮았다. sPEEK MEA(Membrane and Electrode Assembly)와 Nafion 211 MEA의 막 저항이 서로 비슷해 I-V 성능도 거의 같았다. 개미산 투과도가 낮은 sPEEK MEA가 Nafion 211 MEA보다 안정함을 보였다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권1호
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• pp.32-37
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• 2006

In this study, we have purified and characterized the membrane bound nitrate reductase obtained from the denitrifying bacteria, Ochrobactrum anthropi SY509, which was isolated from soil samples. O. anthropi SY509 can grow in minimal medium using nitrate as a nitrogen source. We achieved an overall purification rate of 15-fold from the protein extracted from the membrane fraction, with a recovery of approximately 12% of activity. The enzyme exhibited its highest level of activity at pH 5.5, and the activity was increased up to $70^{\circ}C$. Periplasmic and cytochromic proteins, including nitrite and nitrous oxide reductase, were excluded during centrifugation and were verified using enzyme essay. Reduced methyl viologen was determined to be the most efficient electron donor among a variety of anionic and cationic dyestuffs, which could be also used as an electron donor with dimethyl dithionite. The effects of purification and storage conditions on the stability of enzyme were also investigated. The activity of the membranebound nitrate reductase was stably maintained for over 2 weeks in solution. To maintain the stability of enzyme, the cell was disrupted using sonication at low temperatures, and enzyme was extracted by hot water without any surfactant. The purified enzyme was stored in solution with no salt to prevent any significant losses in activity levels.

• Membrane and Water Treatment
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• 제8권5호
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• pp.395-409
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• 2017

Membrane bioreactor (MBR) is a compact and efficient wastewater treatment and reclamation technology; but, it is limited by membrane fouling. The control of membrane fouling significantly increases operational and maintenance costs. Bacteria and their byproducts - extracellular polymeric substances (EPS) - are major contributors to membrane fouling in MBRs. A recent attempt at fouling mitigation is the development of aerobic granular sludge membrane bioreactor (AGMBR) through the integration of a novel biotechnology - aerobic granulation - and MBR. This paper provides an overview on the development of AGMBR to mitigate membrane fouling caused by bacteria and EPS. In AGMBR, EPS are used up in granule formation; and, the rigid structure of granules provides a surface for bacteria to attach to rather than the membrane surface. Preliminary research on AGMBR using synthetic wastewater show remarkable membrane fouling reduction compared to conventional MBR, thus improved membrane filtration. Enhanced performance in AGMBR using actual municipal wastewater at pilot-scale has also been reported. Therefore, further research is needed to determine AGMBR optimal operational conditions to enhance granule stability in long-term operations and in full-scale applications.

• Korean Membrane Journal
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• 제7권1호
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• pp.19-27
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• 2005

PP hollow fiber membrane was hydrophilized by EVOH dip coating followed by low temperature plasma treatment and UV irradiation. EVOH coating attained high water flux without any prewetting but its stability did not guaranteed at high water permeation rate. At high water permeation rate, water flux declined gradually due to swelling and delamination of the EVOH coating layer causing pore blocking effect. However, plasma treatment reduces the swelling, which suppress delamination of the EVOH coating layer from PP support result in relieving the flux decline. Also, UV irradiation helped the crosslinking of the EVOH coating layer to enhance the performance at low water permeation rate. FT-IR and ESCA analyses reveal that EVOH dip coating performed homogeneously through not only membrane surface but also matrix. Thermogram of EVOH film modified plasma treatment and W irradiation show that crosslinking density of EVOH layer increased. Chemical modification by plasma treatment and UV irradiation stabilized the hydrophilic coating layer to increase the critical flux of the submerged membrane.

• 멤브레인
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• 제31권5호
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• pp.351-362
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• 2021

전 바나듐 레독스 흐름 전지(VRFB)는 유망한 대용량 에너지 저장 기술 중 하나이다. 이온교환막은 VRFB의 충·방전 성능 및 내구성을 좌우하는 핵심 구성 요소이다. 본 연구에서는 기존 탄화수소계 이온교환막의 단점을 보완하기 위해 우수한 물리적 및 화학적 안정성을 갖는 다공성 폴리테트라플루오로에틸렌(PTFE) 지지체의 세공에 불소부가 포함된 탄화수소계 이오노머를 충진하는 방식으로 세공충진 음이온교환막(PFAEMs)을 제조하였다. 얇은 다공성 PTFE 지지체의 사용으로 전기적 저항을 현저히 낮출 수 있었으며 PTFE 지지체의 사용과 더불어 충진 이오노머에 불소부를 도입함으로써 막의 산화 안정성을 크게 향상시킬 수 있었다. 충·방전 성능 평가 결과, PFAEM에 불소부의 함량이 증가할수록 높은 전류 효율을 나타내었으며 낮은 전기적 저항으로 상용막 대비 우수한 전압 효율 및 에너지 효율을 보였다. 또한, 산화 안정성 및 충·방전성능의 관점에서 소수성 PTFE 지지체의 사용이 더 바람직함을 확인하였다.

• 멤브레인
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• 제25권5호
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• pp.415-421
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• 2015

고상반응법을 이용하여 $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$ 조성의 산화물을 합성하였으며, 합성된 분말은 압축 성형 후 $1250^{\circ}C$에서 소결하여 치밀한 세라믹 분리막을 제조하였다. XRD 분석을 통해 단일상의 페롭스카이트 구조를 확인하였다. 산소 분압이 0.21 atm, 측정 온도가 $800{\sim}950^{\circ}C$인 조건하에서 산소투과를 분석한 결과 온도가 증가할수록 산소투과량은 증가하였고, $950^{\circ}C$에서 $1.839mL/min{\cdot}cm^2$로 최대값을 나타내었다. 니오븀(Nb)을 포함한 세라믹 분리막의 상안정성 및 이산화탄소 내성을 확인하기 위하여 $900^{\circ}C$에서 이산화탄소가 500 ppm이 포함된 혼합공기를 이용하여 장기투과 실험을 수행하였다. 이산화탄소에 노출된 $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$의 상안정성은 XRD와 TG로 분석하였다. 분석 결과, 이산화탄소에 노출된 $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$ 조성의 경우 약 8%의 $SrCO_3$가 생성되었으나, 이 수준의 $SrCO_3$ 생성량은 분리막의 산소투과도에 큰 영향을 주지 않는 것을 확인하였다.

• 멤브레인
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• 제17권2호
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• pp.93-98
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• 2007

The reliability of innovative membrane contactors technology (i.e. Gas/Liquid Membrane Contactors, Membrane Distillation/Crystallization) is today increasing for seawater desalination processes, where traditional pressure-driven membrane separation units are routinely operated. Furthermore, conventional membrane operations can be integrated with membrane contactors in order to promote possible improvements in process efficiency, operational stability, environmental impact, water quality and cost. Seawater is the most abundant aqueous solution on the earth: the amount of dissolved salts covers about 3% of its composition, and six elements (Na, Mg, Ca, K, Cl, S) account for more than 90% of ionic species. Recent investigations on Membrane Distillation-Crystallization have shown the possibility to achieve significant overall water recovery factors, to limit the brine disposal problem, and to recover valuable salts (i.e. calcium sulphate, sodium chloride, magnesium sulphate) by combining this technology with conventional RO trains. In this work, the kinetics of $CaSO_4{\cdot}2H_2O,\;NaCl\;and\;MgSO_4{\cdot}7H_2O$ crystallization is experimentally investigated in order to improve the design of the membrane-based crystallization unit.

• 한국막학회:학술대회논문집
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• 한국막학회 1994년도 춘계 총회 및 학술발표회
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• pp.51-52
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• 1994

High permeability, selectivity and stability are the basic properties also required for membrane gas separations. The $CO_2$ separation by liquid membranes has been developed as a new technique to improve the permeability and selectivity of polymeric membranes. Sirkar et al.(1) have atlempted the hollow-fiber contained liquid membrane technique under four different operational modes, and permeation models have been proposed for all modes. Compared to a conventional liquid membrane, the diffusional resistance decreased by the work of Teramoto et al.(2), who referred to a moving liquid membrane. Recently, Shelekhin and Beckman (3) considered the possibility of combining absorption and membrane separation processes in one integrated system called a membrane absorber. Their analysis could be predicted effectively the performance of flat sheet membrane, however, there are restrictions for considering a flow effect. The gas absorption rate is determined by both an interfacial area and a mass transfer coefficient. It can be easily understood that although the mass transfer coefficients in hollow fiber modules are smaller than in conventional contactors, the substantial increase of the interfacial area can result in a more efficient absorber (4). In order to predict a performance in the general system of hollow-fiber membrane absorber, a gas-liquid mass transfor should be investigated inevitably. The influence of liquid velocity on both a mass transfer and a performance will be described, and then compared with experimental results. A present study is attempted to provide the fundamentals for understanding aspects of promising a hollow-fiber membrane absorber.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 추계 총회 및 학술발표회
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• pp.50-53
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• 2004

• 한국막학회:학술대회논문집
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• 한국막학회 1992년도 추계 총회 및 학술발표회
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• pp.55-56
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• 1992

본 연구에서는 산/염기 수용액의 탈수분리에 이미 complex site를 가진 막을 투과증발에 응용하는 것이 아니라, 공급액으로 사용되는 산/염기와 complex를 형성할수 있는 작용기를 가진 막을 그들 수용액의 탈수분리에 응용함으로써 형성된 complex site로 분리성능의 향상을 도모하였다. 또한, 분리대상물내의 한성분이 couter ion으로 작용하는 점을 이용하여 long-term stability의 문제도 해결하고자 하였다.