• Membrane Journal
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• v.16 no.1
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• pp.68-76
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• 2006

This is the research about the concentration of trace citrus flavor components in water by pervaporation. We have investigated the permeation characteristics depending on the material and formation of membranes using four siloxane-based polymer composite membranes. We have also chosen the optimal membrane and investigated the permeation characteristics depending on the feed temperature, concentration and flow rate. And then it has been analyzed by using resistance-in series model. In the permeation experiment of citrus essence aroma model solution through the four siloxane-based polymer composite membranes, PVDF/POMS membranes have showed the best flavor flux and enrichment factor. As a result of the permeation experiment depending on the feed temperature, concentration and flow rate, we can find that as the feed temperature and concentration increase, the flavor flux increases while the enrichment factor decreases. And the flavor flux and enrichment factor increased as the flow rate increases.

• Membrane Journal
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• v.16 no.2
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• pp.159-166
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• 2006

MFI(Mobil Five) structured hydrophobic ZSM-5 zeolite membrane was used for selective pervaporation of trichlorinated organic compounds(trichloromethane, trichloroethane, trichloroethylene) from their aqueous solutions. ZSM-5 zeolite membrane was hydrothermally synthesized on the inside of a porous stainless steel tube by secondary growth employing ZSM-5 seed powders. Separation factors for each binary mixtures were observed $16{\sim}66$ for trichloromethane/water, $3.3{\sim}4.6$ for trichloroethane/water and $1.4{\sim}8$ for trichloroethylene/water at the experimental conditions of the feed mole fraction from 0.0001 to 0.001 with temperature ranged $25{\sim}35^{\circ}C$.

• Membrane Journal
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• v.9 no.2
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• pp.114-125
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• 1999

Dense polymer membranes were made from vanous silicone polymers such as poly(1-trimethylsilyl-1-propyneHPTMSP), poly(dimethylsiloxaneHPDMS), PTMSP- g-PDMS. These membranes were evaluated in terms of the removal of chlorinated organic hydrocarbons such as chloroform, trichloroethylene(TCE), perchloroethylene(PCE) from water by pervaporation. It was possible for membranes used in this study to remove PCE selectively which is dissolved small quantity in water among other separable solutes. PTMSP membranes exhibited a remarkable decay in permeability with time because of the free volume decreases. However, PTMSP-g-PDMS membrane underwent no physical aging and showed the stable flux behavior. From the results of the contact angle measurement, polymeric membranes used in this study showed affinity with solutes for separation and no affinity with water. The relative swelling degree was directly related to the selectivity, while it has no influence on the flux.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.441-447
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• 2016

Development of shale gas has drawn increasing attention since it is one of promising alternative energy resources. However, contamination of groundwater and surface water during the extraction of shale gas is becoming a serious environmental issues, which brings the needs to treat wastewater generated from hydraulic fracking. In this study, the feasibility of membrane distillation (MD) for the treatment of shale gas wastewater was investigated using a laboratory scale experimental setup. Flat-sheet MD membranes were used to treat produced water from a shale gas well in the United States. Different configurations such as direct contact MD (DCMD) and air gap MD (AGMD) were compared in terms of flux and fouling propensity. The foulants on the surface of the membranes were examined. The results suggest that MD can treat the shale gas produced water containing more than 200,000 mg/L of total dissolved solids, which is impossible by other technologies such as reverse osmosis (RO) and forward osmosis (FO). In this study, we investigated the possibility of processing and characterization of shale gas produce wastewater using membrane distillation. Laboratory scale membrane distillation experimental device was developed. It was compared the flat-sheet direct contact membrane distillation and flat-sheet air gap membrane distillation. AGMD flux in lower than the flux of DCMD, it was expected that the contamination caused by organic matters.

• Microbiology and Biotechnology Letters
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• v.20 no.4
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• pp.451-458
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• 1992

Pervaporation which is capable of removing ethanol selectively was adopted to reduce the ethanol inhibition and in situ recovery of ethanol in ethanol fermentation, The composite membrane made of silicone and polysulfone was used to separate the ethanol selectively. The ethanol selectivity of the membrane was about 4 and the total flux was 300 g/m2 h at 301:: and 10 mmHg for 25 g/l of feed concentration. Saccharomyces cerevisiae entrapped within Ca-alginate gels was employed for ethanol fermentations in a fluidized-bed bioreactor. The pervaporation membrane unit and fluidized-bed bioreactor were combined into one system. The proposed model equations for the combined system showed good accordances with the experimental results. It was found from the simulation results that the ethanol concentration in the broth for the combined system was lower than that for the continuous fermentation system without a membrane unit. Ethanol productivity can be thus increased by employing the combined system.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.486-486
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• 2014

CIGS 박막태양 전지는 I-III-VI2 Chalcopyrite 결정구조를 가진 화합물 반도체 태양전지로 인위적인 밴드갭 조작이 용이하여 효율 향상에 높은 가능성을 보이고 있다. 4원소 화합물인 CIGS 광흡수층의 대표적인 제조 방법으로는 co-evaporation 공정법이 있다. 동시 증발법은 CIGS 결정을 최적화하기 위하여 박막이 증착되는 동안 기판의 온도를 3단계로 변화시켜주는 3-stage 공정을 통하여 제작된다. 일반적으로 CIGS 박막태양전지는 전면전극으로 투명전도막이 사용되며 높은 광투과성과 전기전도성을 가져야 한다. 투명전도막의 광학적, 전기적 특성은 CIGS 박막태양전지의 효율에 영향을 미치기 때문에 최적화된 조건이 요구된다. 본 연구에서는 CIGS 광흡수층은 Ga/(In+Ga)=0.31, Cu/(In+Ga)=0.86으로 최적화 시켰으며, 투명전도막은 Al이 도핑된 ZnO 박막을 RF 마그네트론 스퍼터링법을 이용하여 증착하였다. ZnO:Al 박막의 두께를 가변하여 증착하였으며 박막의 특성을 평가하고, CIGS 광흡수층에 이를 적용함으로써 태양전지 변환효율 특성을 연구하였다. CIGS 박막 태양전지의 투명전극인 ZnO:Al 박막의 두께가 500 nm 일 때, Jsc=29.521 mA/cm2, Voc=564 mV, FF factor=71.116%, Efficiency=12.375%의 광 변환효율을 얻을 수 있었으며, 이에 따른 투명 전도막의 전기적, 광학적 특성을 통해 CIGS 박막태양전지에 미치는 영향에 대해 조사하였다.

• The KSFM Journal of Fluid Machinery
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• v.17 no.2
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• pp.30-34
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• 2014

Membrane distillation (MD) is a thermal driven separation process in which separation a hydrophobic membrane is a barrier for the liquid phase, letting the vapor phase pass through the membrane pores. Therefore, a porous and hydrophobic membrane should be used in membrane distillation. MD cannot work if water penetrates into the pores of the membrane (membrane wetting). Accordingly, it is necessary to prevent wetting of MD membranes and to remove water inside the pores of the wetted membranes if possible. In this context, our study aimed to develop methods to recover wetted membranes in MD processes. Poly-vinylidene fluoride (PVDF) membranes were used in this study. A laboratory-scale direct contact MD (DCMD) system was used to examine the effect of operating parameters on wetting. For dewetting the wetted membranes, specific techniques including the use of high temperature air were applied. The performances of the membranes before and after dewetting were compared in terms of flux, salt rejection and liquid entry pressure(LEP). The surface morphology of dewetted membrane was confirmed by scanning electron microscope (SEM).

• Membrane Journal
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• v.20 no.4
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• pp.326-334
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• 2010

In this study, characterization and performance of membrane humidifier using membrane distillation was evaluated for moisture of fuel gas in the PEMFC. The data were expressed dew point. The best results show $51.19^{\circ}C$ at $60^{\circ}C$ of water temperature, $54.22^{\circ}C$ at 900 mL/min and $60.03^{\circ}C$ at 100 strands. The mass transfer modelling of membrane humidifier were able to predict humidification of fuel gases for operating PEMFC. When the membrane humidifier was applied to the 100 W stack, it showed stable voltage and power. The volume of membrane humidifier was small however, showed better performance than bubble humidifier.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.469-474
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• 1998

Poly (vinyl alcohol) (PVA) membranes crosslinked with poly (styrene-co-maleic anhydride) (PSMAn) have been prepared by the solution method. To investigate the separation behavior of the crosslinked PVA/PSMAn membranes in the pervaporation process, the selective sorption experiment and swelling measurements of the membranes in ethanol-water mixtures of 30~90 wt % ethanol contents were conducted with equipment that was able to measure the concentration and amount of the liquid absorbed in the membranes. The membranes prepared in this study exhibited good selectivity toward water component in sorption and permeation. Also, in the feed containing ethanol more than 50 wt %, the permeation selectivity of the membrane showed better correlation with the sorption selectivity than that with the swelling ratio changing toward the crosslinking content. This behavior was consistence with a solution-diffusion model correlating permeation and sorption selectivity, and led to the conclusion that the permeation selectivity was determined by sorption step rather than by diffusion step in the membrane.

• Membrane Journal
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• v.9 no.1
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• pp.51-62
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• 1999

The recovery of trace volatile organic components from water by pervaporation was investigated. Permeation experiments through homogeneous polydimethylsiloxane(PDMS) membrane was carried out and the effect of feed concentrations and membrane thicknesses on the permeation characteristics were investigated. A solution-diffusion model is used to describe the pervaporation transport mechanism. In homogeneous PDMS membrane it appeared that the selectivities of MEK and toluene are constant, and that organic flux has a linear relationship with feed concentration. These results indicate that the coupling effects between organics were negligible. The selectivity of PDMS membranes is invariant with respect to the membrane thickness. The intrinsic membrane permeability of organic components determined by using a solution-diffusion model. Comparing with various composite type membrane, the membrane using PEG treated nonwoven fabric as sublayer showed the best performance in VOC recovery by pervaporation.