• 멤브레인
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• 제21권3호
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• pp.256-262
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• 2011

저농도의 $SF_6$를 포함하고 있는 기체 혼합물(10% $SF_6$/70% $N_2$/19% $O_2$/1% $CF_4$)로부터 $SF_6$를 분리 및 회수하기 위한 PSF막과 PC막의 성능에 대하여 연구하였다. 회수된 기체 내의 $SF_6$의 농도와 회수율 그리고 혼합기체($N_2/SF_6$, $O_2/SF_6$, $CF_4/SF_6$)의 선택도는 배출 유량과 온도의 함수로 측정하였다. PSF막과 PC막 모두 회수된 기체 내의 $SF_6$ 농도는 배출 유량이 증가하면서 감소하였으며 온도가 증가함에 따라 증가하였다. 동일한 실험조건에서는 PSF막에서 회수된 기체 내의 $SF_6$의 농도가 PC막에서보다 높게 나타났다. 최대회수율은 298.15 K과 배출유량 150cc/min에서 PSF막의 경우 95.9%이고 PC막의 경우 67.8%를 나타냈다. $CF_4/SF_6$를 제외한 $N_2/SF_6$와 $O_2/SF_6$의 실제 선택도는 PSF막이 PC막보다 더 높게 나타났다.

• Korean Membrane Journal
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• 제8권1호
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• pp.1-12
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• 2006

In semiconductor industries, dissolved oxygen is one of the most undesirable contaminants of ultrapure water. A method for dissolved oxygen removal (DOR) consists in the use of polymeric hollow fibres, loaded with a catalyst and fed with a reducing agent such as hydrogen. In this work, PVDF hollow fibres loaded with Pd were characterized by means of perporometry, scanning electron microscopy (SEM), energy dispersive X-ray (EDX). The hollow fibre analyzed shows a five-layer structure with remarkable morphological differences. An estimation of pore diameters and their distribution was performed giving a mean pore diameter of 100 nm. The permeance and selectivity of the fibres were measured using $H_2,\;N_2,\;O_2$ as single gases, at different operating conditions. An $H_2$ permeance of $37 mmol/m^2s$ was measured and $H_2/O_2$ and $H_2/N_2$ selectivities of ca. 3 were obtained. $H_2$ permeance was 1/3 when a water stream flows in the shell side. Catalytic fibrebehaviour was simulated using a mathematical model for a loop membrane reactor, considering only $O_2$ and $H_2$ diffusive transport inside the membrane and their catalytic reaction. Dimensionless parameters such as the Thiele modulus are employed to describe the system behaviour. The model agrees well with the experimental reaction data.

• Macromolecular Research
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• 제11권3호
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• pp.157-162
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• 2003

6FDA-based polyimides were prepared from the thermal imidization reaction of 6FDA with diamines of BAPAF, DAP, and DABA having a polar group of hydroxyL or carboxyl. Properties of the dense polyimide membranes were characterized and their gas permeation properties for H$_2$, $CO_2$, $O_2$, $N_2$, and CH$_4$ were investigated. Permeabilities, diffusion coefficients and diffusivity selectivities of polar group-containing polyimide membranes including 6FDA-BAPAF, 6FDA-DAP, and 6FDA-DABA polymer for the gases did not change largely. The separation properties of 6FDA-TrMPD polyimide membrane used as a reference polymer were compared with those of the polyimide membranes mentioned above. It was found that the polyimides of 6FDA-BAPAF, 6FDA-DAP, and 6FDA-DABA, which were soluble in alcohol or/and 2-methoxyethanol, could be applicable to the preparation of a dense composite membrane by dip-coating method.

• 멤브레인
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• 제23권2호
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• pp.176-184
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• 2013

다성분계 휘발성 유기화합물(VOCs; Volatile Organic Compounds)의 분리를 위하여 상전이법을 이용하여 방사한 poly (ether imide) (PEI) 중공사 지지체에 poly (dimethylsiloxane) (PDMS)를 코팅하여 중공사 복합막을 제조하였다. VOCs 회수용 중공사막으로서 적합성을 알아보기 위해서 중공사막의 모폴로지, 질소 및 산소 기체 투과도를 측정하고, 벤젠, 톨루엔 그리고 자일렌에 대한 내구성을 조사하였다. 다성분계 휘발성 유기화합물의 효과적인 분리성능을 조사하기 위하여 Stage-cut과 feed 농도에 따른 다성분계 VOCs 투과 성능 변화를 관찰하였다. PEI 지지체 중공사막에 PDMS를 코팅시킴에 따라 산소와 질소 투과도는 각각 45,000 GPU와 49,450 GPU에서 63 GPU와 30 GPU로 감소하는 것을 확인하였다. VOCs 투과농도는 Stage-cut이 감소함에 따라 증가하나, 회수율은 감소하였다. 반면에 공급농도 증가에 따라 투과농도는 비례적으로 증가하였지만, 농축비나 회수율은 큰 변화가 없었다.

• 멤브레인
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• 제12권2호
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• pp.107-119
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• 2002

이번 연구에서 효율적인 기체분리를 위한 탄소-실리카($C-SiO_2$) 분리막이 방향족 이미드 블록과 실록산 블록으로 구성된 공중합체의 비활성분위기에서의 열분해를 통해 제조되었다. 이 탄소-실리카 기체분리막은 비교적 작은 크기의 기체분리, 즉 $He/N_2, O_2/N_2$ 그리고 $Co_2/N_2$의 분리에 있어 매우 뛰어난 기체선택도를 나타내었다. 두 상을 가진 공중합체의 열분해는 600도, 800도 그리고 1000도의 최종열분해온도로서 수행되었으며, 이러한 두 상으로 이루어진 전구체는 탄소막의 제조에 처음으로 보고되었다. 이러한 전구체는 두 상의 조성 및 같은 조성에서 중합방법의 차이에 의해 형성되는 모폴로지의 변화가 최종 탄소-실리카막의 기체분리특성에 미치는 영향을 살피기 위해 제조되었다. 이러한 탄소-실리카분리막은 $2.6-3.6{\AA}$의 동력학적 반경을 가진 작은 기체분자(헬륨, 산소, 질소, 이산화탄소)들을 사용한 기체투과실험에서, 탄소-실리카 분리막은 높은 투과도와 함께 뛰어난 분자체 효과를 보였다. 게다가 탄소-실리카분리막의 기체분리특성은 사용한 고분자 전구체의 기체분리특성과 매우 유사하며, 이것은 열적으로 안정한 두상의 사용으로 전구체의 초기 모폴로지가 열처리 후에도 상당히 유지되었기 때문이다. 현재의 연구는 탄소막 전구체의 초기의 모폴로지가 최종 탄소막의 분리특성 및 미세구조에 결정적인 영향을 미침을 암시한다.

• Macromolecular Research
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• 제16권6호
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• pp.555-560
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• 2008

A series of hydroxyl-group containing polyimides (HPIs) were prepared in order to investigate the structure-gas permeation property relationship. Each polymer membrane had structural characteristics that varied according to the dianhydride monomers. The imidization processes were monitored using spectroscopic and thermog-ravimetric analyses. The single gas permeability of He, $H_2$, $CO_2$, $O_2$, $N_2$ and $CH_4$ were measured and compared in order to determine the effect of the polymer structure and functional -OH groups on the gas transport properties. Surprisingly, the ideal selectivity of $CO_2/CH_4$ and $H_2/CH_4$ increased with increasing level of -OH incorporation, which affected the diffusion of $H_2$ or the solubility of $CO_2$ in HPIs. For $H_2/CH_4$ separation, the difference in the diffusion coefficients of $H_2$ and $CH_4$ was the main factor for improving the performance without showing any changes in the solubility coefficients. However, the solubility coefficient of $CO_2$ in the HPIs increased at least four fold compared with the conventional polyimide membranes depending on the polymer structures. Based on these results, the polymer membranes modified with -OH groups in the polymer backbone showed favorable gas permeation and separation performance.

• Carbon letters
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• 제16권3호
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• pp.183-191
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• 2015

Gas transport through graphene-derived membranes has gained much interest recently due to its promising potential in filtration and separation applications. In this work, we explore Kr-85 gas radionuclide sequestration from natural air in nanoporous graphene oxide membranes in which different sizes and geometries of pores were modeled on the graphene oxide sheet. This was done using atomistic simulations considering mean-squared displacement, diffusion coefficient, number of crossed species of gases through nanoporous graphene oxide, and flow through interlayer galleries. The results showed that the gas features have the densest adsorbed zone in nanoporous graphene oxide, compared with a graphene membrane, and that graphene oxide was more favorable than graphene for Kr separation. The aim of this paper is to show that for the well-defined pore size called P-7, it is possible to separate Kr-85 from a gas mixture containing Kr-85, O₂ and N₂. The results would benefit the oil industry among others.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1769-1774
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• 2006

A new liquid chromatographic chiral stationary phase based on (2S,3S)-O,O'-bis-(10-undecenoyl)-N,N'-bis-(3,5-dinitrobenzoyl)-2,3-diamino-1,4-butandiol was prepared starting from (2R,3R)-1,4-bis(benzyloxy)-2,3-butanediol. The new chiral stationary phase was applied to the resolution of racemic anilide derivatives of N-acetyl-a-amino acids, 1,1'-bi-2-naphthol and 3,3'-diaryl-1,1'-bi-2-naphthols. The CSP was also applied to the resolution of some chiral drugs including a diuretic, bendroflumethiazide, and non-steroidal anti-inflammatory agents such naproxen and alminoprofen. In every case, the chiral recognition efficiency of the new CSP was quite excellent.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3671-3676
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• 2013

A series of carbon nanotube, $C_{60}$, and graphene modified $TiO_2$ nanocomposites were prepared by hydrothermal method. X-ray diffraction, $N_2$ adsorption, UV-Vis spectroscopy, photoluminescence, and Electrochemical impedance spectra were used to characterize the prepared composite materials The results reveal that incorporating $TiO_2$ with carbon materials can extend the adsorption edge of all the $TiO_2$-carbon nanocomposites to the visible light region. The photocatalytic activities were tested in the degradation of 2,4,6-trichlorophenol (TCP) under visible light. No obvious difference in essence was observed in structural and optical properties among three series of carbon modified $TiO_2$ nanocomposites. Three series of carbon materials modified $TiO_2$ composites follow the analogous tentative reaction mechanism for TCP degradation. GR modified $TiO_2$ nanocomposite exhibits the strongest interaction and the most effective interfacial charge transfer among three carbon materials, thus shows the highest electron-hole separation rate, leading to the highest photocatalytic activity and stability.

• 분석과학
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• 제10권6호
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• pp.403-407
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• 1997

Anchor group으로서 1,7,13-trioxa-4,10,16-triazacyclooctadecane($N_3O_3$)을 가지고 있는 이온교환수지를 사용하여 $^6Li$와 $^7Li$의 분리인자를 측정하였다. 가벼운 동위원소 $^6Li$는 액상에, 무거운 동위원소 $^7Li$는 이온교환수지상에 농축되었다. 2.0M 염화암모늄 용액을 용리액으로 사용한 컬럼 [0.9cm(내경)${\times}$20cm(높이)] 크로마토그래피에 의하여, 1.009의 분리인자, ${\alpha}$, $(^7Li/^6Li)_{resin}$/$(^7Li/^6Li)_{solution}$값을 얻었다. 이 값은 용리곡선과 동위원소비로부터 Glueckauf 이론을 적응하여 얻은 것이다.