• Membrane Journal
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• v.24 no.1
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• pp.69-77
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• 2014

To prepare the hollow fiber nanofiltration composite membranes, the poly(vinylidene fluoride) (PVDF) membrane was hydrophilized with $K_2Cr_2OH$ and $KMnO_4$ aqueous solutions. And then the composite membrane was synthesized on that membrane surfaces using interfacial polymerization with piperazine (PIP) and trimesoyl chloride (TMC). The resulting membranes were characterized in terms of the rejection and flux for NaCl, $CaSO_4$, $MgCl_2$ 100 ppm solution and 300 ppm of NaCl and $CaSO_4$ mixed solution by varying the coating time, drying time, and the concentration of the coating materials. As a result, the higher rejections were shown for $K_2Cr_2OH$ solutionas a hydrophilization material, and the flux was enhanced while the rejection reduced as the hydrophilization time is longer. Also, the rejection increased and the flux reduced as the concentrations of triethyl amine (TEA) and sodium lauryl sulfate (SLS) were higher. Typically, the rejection 50% and flux 40 LMH for NaCl 100 ppm solution, and the rejection 55% and flux 48 LMH for $CaSO_4$ 100 ppm solution were obtained for the PVDF hollow fiber composite membrane prepared with the conditions of PIP 2 wt% (Triethyl amine (TEA) 7 wt%, SLS 20 wt% mixed solution against PIP concentration) and TMC 0.1 wt%.

• Membrane and Water Treatment
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• v.8 no.4
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• pp.311-321
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• 2017

Hydrophilic and high modulus PPTA molecules were incorporated into PVDF matrix via the in situ polymerization of PPD and TPC in PVDF solution. PPTA/PVDF/NWF blend membrane was prepared through the immersion precipitation phase inversion method and nonwoven coating technique. The membrane integrated technology including PPTA/PVDF/NWF blend membrane and reverse osmosis (RO) membrane was employed to treat the polyester/viscose spunlace nonwoven process wastewater. During the consecutive running of six months, the effects of membrane integrated technology on the COD, ammonia nitrogen, suspended substance and pH value of water were studied. The results showed that the removal rate of COD, ammonia nitrogen and suspended substance filtered by PPTA/PVDF blend membrane was kept above 90%. The pH value of the permeate water was about 7.1 and the relative water flux of blend membrane remained above 90%. After the deep treatment of RO membrane, the permeate water quality can meet the water circulation requirement of spunlace process.

• Membrane Journal
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• v.28 no.3
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• pp.180-186
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• 2018

The nano-composite membranes were prepared onto the polyvinylidene fluoride (PVDF) hollow fiber membranes through twice dip-coating known layer-by-layer method. For the first coating, poly(vinylsulfonic acid, sodium salt)(PVSA) and Poly(styrene sulfonic acid)(PSSA) were used with varying the concentration and ionic strength (IS) and the poly(ethyleneimine)(PEI) as the second coating material was fixed at 10,000 ppm and IS = 0.3. To characterize the prepared nano-composite membranes, the permeabilities and rejection ratio were measured for each 100 ppm NaCl, $CaSO_4$, $MgCl_2$, and 25 ppm MO aqueous solution. The rejections were increased as the concentrations of coating materials increased. And it was confirmed that the salt rejections for PSSA as the coating material were higher than for PVSA. Typically, the permeability, 1.848 LMH and the rejection for MO 76.3% were obtained at the coating conditions of PSSA 30,000 ppm and I.S = 1.0.

• Clean Technology
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• v.16 no.1
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• pp.39-45
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• 2010

In this paper, 4 bundle modules of PVDF hollow fiber membrane from Woori Tech company (Korea) were manufactured in a treatment capacity of 10 ton/day. A membrane bioreactor (MBR) pilot plant was installed at Sooyoung Wastewater Treatment Plant in Busan. An alternating aeration process was selected to avoid the concentration profile of suspended solid (SS) in the MBR. For stable operation, raw wastewater with mixed liquor suspended solid (MLSS) of about 1,000 ppm, which was in-flowed from the aeration tank of the wastewater treatment plant, was fed and filtered through the pilot plant. Subsequently the pilot plant were washed three times with washing water: once with ethanol solution, once with a solution of 5% NaOCl, and finally with washing water. After the chemical washing, the remaining water in the MBR was fed into the pilot plant. As a result, the SS removal efficiency was found to be more than 99.9%. The amount of filtrate with the aeration tank influent decreased by 16%, compared with that from the initial conditions, giving rise to 30% increase in the suction pressure. These results were used to set up continuous operation conditions. The results from the continuous operation with influent MLSS of 1,900 mg/L showed that the SS removal efficiency was about 99.99% and that the amount of filtrate and the suction pressure were $42{\sim}52L/m^2$ and 16~20 cmHg, respectively, indicating stable operation of the pilot plant. However, for the reuse of wastewater, methods need to be sought to avoid growth of algae which affects the SS removal efficiency at inlet and outlet of the permeate tank.

• Membrane and Water Treatment
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• v.10 no.2
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• pp.113-120
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• 2019

To investigate surface properties and interception performances of the new modified PVDF membrane coated with Graphene Oxide (GO) and nano-$TiO_2$ (for short the modified membrane) via the interface polymerization method combined with the pumping suction filtration way, filtration experiments of the modified membrane on Humic Acid (HA) were conducted. Results showed that the contact angle (characterizing the hydrophilicity) of the modified membrane decreased from $80.6{\pm}1.8^{\circ}$ to $38.6{\pm}1.2^{\circ}$. The F element of PVDF membrane surface decreased from 60.91% to 17.79% after covered with GO and $TiO_2$. O/C element mass ratio has a fivefold increase, the percentage of O element on the modified membrane surface increased from 3.83 wt% to 20.87%. The modified membrane surface was packed with hydrophilic polar groups (like -COOH, -OH, C-O, C=O, N-H) and a functional hydrophilic GO-polyamide-$TiO_2$ composite configuration. This configuration provided a rigid network structure for the firm attachment of GO and $TiO_2$ on the surface of the membrane and for a higher flux as well. The total flux attenuation rate of the modified membrane decreased to 35.6% while 51.2% for the original one. The irreversible attenuation rate has dropped 71%. The static interception amount of HA on the modified membrane was $158.6mg/m^2$, a half of that of the original one ($295.0mg/m^2$). The flux recovery rate was increased by 50%. The interception rate of the modified membrane on HA increased by 12% approximately and its filtration cycle was 2-3 times of that of the original membrane.

• Membrane Journal
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• v.23 no.4
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• pp.312-318
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• 2013

Poly vinylidene fluoride (PVDF) hollow fiber membranes were hydrophilized using polyethylenimine (PEI) and p-xylylene dichloride (XDC), and poly(vinyl alcohol) (PVA) and poly (acrylic acid -co- maleic acid) (PAM) mixed solutions by varying the concentration of PAM were coated onto PVDF membrane surface. The surface coating was verified by the observation of scanning electron microscope (SEM) and the permselective characteristcs of the resulting composite membranes were tested for 90 wt% aqueous ethanol solution by the pervaporation technique. The effects of the corsslinking agent concentraion, the temperature of feed solution, and the reaction temperature on the flux and separation factors were measured. Typically, the flux, $1,480g/m^2hr$ at the reaction temperature $100^{\circ}C$, PAM 3 wt%, feed temperature $70^{\circ}C$ was obtained, on the other hand, for the separation factor, ${\alpha}_{W/E}=82$ at the conditions of the reaction temperature $100^{\circ}C$, PAM 15 wt% and feed temperature $25^{\circ}C$ was shown.

• Journal of the Korean Solar Energy Society
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• v.34 no.5
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• pp.23-31
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• 2014

This study was accomplished to get the foundation design data of VMD(Vacuum Membrane Distillation) system for Solar Thermal VMD plant. VMD experiment was designed to evaluate thermal performance of VMD using PVDF(polyvinylidene fluoride) hollow fiber hydrophobic membranes. The total membrane surface area in a VMD module is $5.3m^2$. Experimental equipments to evaluate VMD system consists of various parts such as VMD module, heat exchanger, heater, storage tank, pump, flow meter, micro filter. The experimental conditions to evaluate VMD module were salt concentration, temperature, flow rate of feed sea water. Salt concentration of feed water were used by aqueous NaCl solutions of 25g/l, 35g/l and 45g/l concentration. As a result, increase in permeate flux of VMD module is due to the increasing feed water temperature and feed water flow rate. Also, decrease in permeate flux of VMD module is due to increasing salinity of feed water. VMD module required about 590 kWh/day of heating energy to produce $1m^3/day$ of fresh water.

• Membrane Journal
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• v.24 no.2
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• pp.107-112
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• 2014

The composite membranes were prepared on the surface of hydrophobic porous poly (vinylidene fluoride) (PVDF) hollow fiber membranes through the interfacial polymerization. The preparation variables were the concentrations of piperazine (PIP), trimesoyl chloride (TMC) and the contents of polyethylene glyco l (PEG). The separation characterization of the resulting membranes were carried out for aqueous 100 ppm solution of NaCl, $CaSO_4$, and $MgCl_2$ and also mixed 300 ppm solution of NaCl and $CaSO_4$ in terms of the flux and rejection. Both the flux and rejection were the highest when the interfacial polymerization was conducted using TMC. When TMC concentration was 0.1 wt%, the flux and rejection were shown 48.3 LMH ($L/m^2{\cdot}hr$) and 59%, respectively. To improve the flux, the annealing post-treatment and the addition of PEG into piperazine were done. As expected, the overall flux was enhanced while the rejection was reduced.

• Journal of Hydrogen and New Energy
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• v.18 no.3
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• pp.223-229
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• 2007

여과막 생물반응기를 이용하여 $60^{\circ}C$에서 혐기 세균 복합체가 포도당으로부터 수소를 생산할 수 있는 최적조건을 연구하였다. 여과막 생물반응기는 연속교반 탱크반응기와 외부에 장착된 PVDF (polyvinylidene fluoride) 중공사막 여과장치로 구성되었다. 접종슬러지는 하수처리장 소화 슬러지조에서 얻었고, 포자형성 수소생산 미생물을 얻기 위해 $90^{\circ}C$에서 20분 간 열처리하였다. 16S rRNA PCR-DGGE(polymer chain reaction-denaturing gradient gel electrophoresis) 분석을 통해 열처리 전후의 미생물상 변화를 조사하였다. 열처리 후 DGGE 밴드의 수는 감소하였고, 주요 밴드는 Clostridium perfringens와 유사한 염기서열을 나타내었다. 운전 기간 동안 바이오가스 내 수소함량은 60%(v/v)를 유지하였고, 메탄은 검출되지 않았다. 연속교반 탱크반응기를 여과막 없이 수력학적 체류 4시간에서 운전하였을 때 공급된 포도당의 95.0%가 제거되었고, 이때 균체농도 및 수소생산속도는 각각 1.35 g cell/L 및 7.4 L $H_2$/L/day이었다. 동일한 체류시간에서 PVDF중공사막 여과장치를 장착하여 연속교반 탱크반응기를 운전하였을 때, 균체농도는 1.62 g cel/L로 증가하였고 높은 포도당 제거율(99.5%) 및 수소생산속도(8.8 L $H_2$/L/day)가 관찰되었다. 40 nm 및 100 nm의 공극크기를 가진 여과막은 균체농도 및 수소생산 측면에서 유사한 성능을 나타내었다. 여과막 생물반응기는 여과막의 반복적인 세척을 통해 30일 이상 안정적으로 운전될 수 있었다.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.327-334
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• 2016

The effects of dissolved inorganic and organic matter in seawater and the characteristics of fouling on the membrane surface were investigated within membrane distillation (MD) process. The changes of the membrane flux of PE and PVDF hollow fiber membranes under natural and synthetic seawater were compared with given variances of temperature. The flux of both membranes under the synthetic seawater, without any organic matter, were higher than that of the natural seawater, indicating the organic fouling on the membrane surface. The surface of the membrane was analyzed using scanning electron microscope (SEM) to examine the fouling. The experiment with organics has shown the formation of thin film over the membrane surface, while the experiment with inorganics has shown only the formation of inorganic crystals. The results indicated the organic matter as the major foulants and that the organics affected the formation of the crystals. Permeate water conductivity of all conditions verified the quality of the water to be better if not similar to that of RO.