• Membrane Journal
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• v.22 no.5
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• pp.326-331
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• 2012

In this study, rejection behavior of 2-MIB (methylisoborneal) and geosmin which are known as taste-and-odor (T & O) causing micropollutants in drinking water source was investigated using hydrophobic polyethersulfone (PES) nanofiltration "loose" membrane (MWCO : 400 Da). It was found that the rejection of the geosmin was higher than that of the 2-MIB in all experimental conditions tested. This study also showed that the rejections of 2-MIB and geosmin were increased by increasing solution pH due to enhancing electrostatic repulsions between micropollutants and membrane surface. The presence of natural organic matter led to increase the rejection of the hydrophobic 2-MIB and geosmin and the effectiveness was more pronounced at higher solution pH. Increasing hydrophilicity of the hydrophobic membrane surface by coating with $TiO_2$ particles resulted in the significant increase in the rejection of 2-MIB and geosmin. In addition to the charge repulsion, this result suggests that hydrophobic-hydrophobic interaction should be one of main rejection mechanisms of T & O compounds by NF membrane.

• Membrane Journal
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• v.29 no.6
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• pp.348-354
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• 2019

Recently, the application range of organic solvent nanofiltration (OSN) technology has been expanding, requiring membranes with better performance. In this work, thin film composite (TFC) OSN membrane was fabricated. First, ultrafiltration support membrane was prepared via nonsolvent-induced phase separation (NIPS) technique using polysulfone (PSf) and polyethersulfone (PES). Then, the effect of pore forming additives such as polyvinylpyrrolidone (PVP) and pluronic F-127 were employed to improve the membrane permeance. The well-known interfacial polymerization technique was employed using MPD-TMC chemistry to form a thin film on top of the fabricated support, and its solvent permeance and nanofiltration performance was characterized. It was found that polyethersulfone support exhibited more reliable performance compared to polysulfone, and PVP additive was more effective compared to Pluronic F-127. As for the oSN performance, polar aprotic solvents like acetonitrile show significantly higher flux (986.5 L·m^-2·h^-1·bar^-1) compared to water and EtOH (9.5 L·m^-2·h^-1·bar^-1).

• Environmental Engineering Research
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• v.23 no.3
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• pp.316-322
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• 2018

In this study, the effects of polymer concentration and additive in the formation of asymmetric nanofiltration (NF) membrane were evaluated. The membrane fabrication was carried out via dry/wet phase inversion technique. A new formulation of dope solution with polymer concentration ranging between 17 wt% to 21 wt% and the present of additive was developed. The results show that the permeate flux gradually decreases as polymer concentration increased, until $2.5969L/m^2h$ and increased the rejection up to 98.7%. Addition of additive, polyethylene glycol 600 increased dyes rejection up to 99.8% and decreased the permeate flux to $3.6501L/m^2h$. This indicates that the addition of polyethylene glycol additive led towards better membrane performance. The morphological characteristics of NF membrane were analysed using a Scanning Electron Microscopy.

• Membrane Journal
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• v.15 no.1
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• pp.34-43
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• 2005

The poly(vinyl alcohol) (PVA)-based thin film composite nanofiltration (NF) membranes were prepared by coating polysulfone ultrafiltration membranes, sulfonated polyethersulfone and polyamide NF membranes with aqueous PVA solution by a pressurizing method. The PVA was cross-linked with aqueous glutaraldehyde solution. The NF membranes coated with a very low concentration of PVA on all the support membranes was successfully prepared. With increasing the hydrophilicity of the support membranes, the water flux increased. Especially, ζ-potential of negatively charged polyamide NF membrane was reduced by coating the membrane with PVA. A fouling experiment was carried out with positively charged surfactant, humic acid, complex of humic acid and calcium ion and bovine serum albumin. A non-coated polyamide NF membrane was significantly fouled by various foulants. The fouling process when using humic acid and protein occurred at the isoelectric point. There was severe fouling when using humic acid and adding bivalent cations. By coating the polyamide NF membrane with aqueous PVA solution, fouling was reduced. The polyamide NF membrane coated with PVA was resistant to the acidic and basic solution.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.60-61
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• 1994

복합막은 기존의 비대칭막에 비해서 극히 얇은 표면층을 형성할 수 있다. 이러한 복합막은 배제율도 우수할 뿐만아니라 투과속도 또한 매우 큰 특징을 가지고 있으며, 해수의 담수화를 비롯하여 초순수 제조 등 각종 산업분야에서 많이 응용되고 있다. 우수한 분리막을 제조하기 위해서는 막의 표면층을 보다 더 치밀하고 얇게 형성할 수 있어야 한다. 이렇게 하기 위해서는 지지막 또한 매우 중요한 요인으로 작용한다. 표면층이 치밀하고, 가능한 한 porosity가 큰 지지막을 제조해야한다. 따라서 본 연구에서는 고분자 물질로 Polyethersulfone을 사용하여 지지막을 만들었다. 이 지지막위에 계면중합법으로 NF/RO용 복합막을 제조하였다. 높은 투과 속도 및 염의 배제율이 우수한 복합막을 제조하기 위해서 먼저 Polymer 농도, 첨가제 종류및 농도 등에 의한 각종 제막조건에 따른 지지막의 성능을 조사하였다. 여기에 Monomer 농도를 변화시켜서 계면중합으로 복합막을 제조하여 그 성능 변화를 측정하였다.

• Membrane and Water Treatment
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• v.4 no.2
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• pp.83-93
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• 2013

In the present investigation, were synthesized composite membranes prepared by simultaneous casting of two polymer solutions using the technique of phase inversion by immersion / precipitation. The support layer was prepared using polyethersulfone and polysulfone as base polymer and for the top layer was used sulfonated polysulfone (SPSU) with 50% sulfonation degree. The morphology of the resulting membranes were characterized by scanning electron microscopy (SEM). The final results showed that it is possible to prepare composite membranes by simultaneous casting of two polymer solutions with adherence between the two layers. Regarding the permeation tests, the developed membranes presented values of hydraulic permeability within the range of commercial nanofiltration (NF) membranes. Values rejection of 80% ammonium ions can be increased by using a SPSU with a greater degree of sulfonation.

• Membrane Journal
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• v.18 no.2
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• pp.185-190
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• 2008

In a previous study, we probed the potential of poly(styrene sulfonate) (PSS)/poly(diallyldimethylammonium chloride) (PDADMAC) nanofiltration (NF) membranes for the separation of monovalent anions, with an emphasis on the selective rejection of $F^-$. Remarkably, deposition of $(PSS/PBADMAC)_4PSS$ films on porous alumina supports yielded membranes that exhibited $Cl^-/F^-$ selectivity > 3 with minimal $Cl^-$ rejection, and a solution flux of $3.5m^3/m^2$-day at 4.8 bar. When the number of PSS/PDADMAC bilayers was increased from 4.5 to 5.5, however, $F^-$ rejection decreased from 73% to 50% and $Cl^-/F^-$ selectivity dropped to 1.9. Addition of another bilayer to form $(PSS/PDADMAC)_6$ PSS films resulted in a significant increase in $Cl^-$ rejection to give essentially no $Cl^-/F^-$ selectivity. The decrease of selectivity with deposition of more than 4.5 bilayers was not expected and it was unclear whether this characteristic was substrate independent. In this study, to investigate the effect of substrates on NF performance of multilayer polyelectrolyte membranes, PSS/PDADMAC films were deposited on 50 kDa polyethersulfone (PES) ultrafiltration supports instead of porous alumina supports. The results indicate that, although fluoride rejection and the number of bilayers at which a maximum $F^-$ rejection occurs are different, the trend is similar for both types of substrates. Therefore, we can conclude that the M: characteristics of multilayer polyelectrolyte membranes may be substrate independent.