• Journal of the Korean Ceramic Society
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• v.33 no.6
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• pp.700-708
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• 1996

TiO2 membranes for microfiltration were prepared on $\alpha$-alumina support tube by slurry coating. The coating layer was obtained by flowing TiO2 slip on the inner surface of the alumina support. TiO2 membranes were heat-treated at 9$25^{\circ}C$ for 2 hrs. The thickness of the unsupported membrane was about 10${\mu}{\textrm}{m}$. The mean pore diameter of the membranes were 0.09 and 0.15${\mu}{\textrm}{m}$ respectively and the pure water flux was 900~1,200ι/m2.hr at room temperature and 1 bar. For a possible application of oily wastewater treatement an kerosene/wa-ter emulsion was separated in terms of flux and removal efficiency. In 60 min of operating time the flux of TiO2 membranes was 50~100 ι/m2.hr and removal efficiency was over 97% at 3kgf/cm2 of operating pres-sure and 600 ml/min of flow rate. TiO2 membranes could be recycled by reheat treatments at $600^{\circ}C$ for 2 hrs.

• Membrane and Water Treatment
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• v.1 no.2
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• pp.103-120
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• 2010

Surface modification of microfiltration and ultrafiltration membranes has been widely used to improve the protein adsorption resistance and permeation properties of hydrophobic membranes. Several surface modification methods for converting conventional membranes into low-protein-binding membranes are reviewed. They are categorized as either physical modification or chemical modification of the membrane surface. Physical modification of the membrane surface can be achieved by coating it with hydrophilic polymers, hydrophilic-hydrophobic copolymers, surfactants or proteins. Another method of physical modification is plasma treatment with gases. A hydrophilic membrane surface can be also generated during phase-inverted micro-separation during membrane formation, by blending hydrophilic or hydrophilic-hydrophobic polymers with a hydrophobic base membrane polymer. The most widely used method of chemical modification is surface grafting of a hydrophilic polymer by UV polymerization because it is the easiest method; the membranes are dipped into monomers with and without photo-initiators, then irradiated with UV. Plasma-induced polymerization of hydrophilic monomers on the surface is another popular method, and surface chemical reactions have also been developed by several researchers. Several important examples of physical and chemical modifications of membrane surfaces for low-protein-binding are summarized in this article.

• Membrane and Water Treatment
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• v.5 no.4
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• pp.235-250
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• 2014

The impacts of membrane degradation due to chlorine attack on the rejection of inorganic salts and trace organic contaminants by nanofiltration (NF) and reverse osmosis (RO) membranes were investigated in this study. The rejection of trace contaminants was examined at environmentally relevant concentrations. Changes in the membrane surface morphology were observed as a result of chlorine exposure. A small increase in rejection was consistently observed with all four membranes selected in this study after being exposed to a low concentration of hypochlorite (100 ppm). In contrast, a higher concentration of hypochlorite (i.e., 2000 ppm) could be detrimental to the membrane separation capacity. Membranes with severe chlorine impact showed a considerable decrease in rejection over filtration time, possibly due to rearrangement of the polyamide chains under the influence of chlorine degradation and filtration pressure. The reported results indicate that loose NF membranes are more sensitive to chlorine exposure than RO membranes. The impact of hypochlorite exposure (both positive and negative) on rejection is dependent on the strength of the hypochlorite solution and is more significant for the neutral carbamazepine compound than the negatively charged sulfamethoxazole.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.1
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• pp.56-60
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• 2014

The polyimide composite membranes were prepared with polyimide composite solutions including graphenes by using the phase inversion method. The morphologies of these membranes were significantly changed according to the graphene loadings in composite solutions and the solvent systems of the composite solutions. The finger-like macro-voids were formed in the hollow fiber membranes which were prepared in the NMP solvent system with a small amount of ethanol. As increasing the content of the viscous alcohols such as glycerol or 1,3-propanediol in the composite solution, however, the morphologies of the hollow fiber membranes were changed to sponge-like types. In case of flat membranes, the increase of graphene content in polyimide composites causes that their membranes change from the finger-like macro-porous to sponge-like morphologies.

• Membrane and Water Treatment
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• v.8 no.1
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• pp.89-112
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• 2017

Dyeing wastewaters are the most problematic wastewater in textile industries and also, growing amounts of waste fibers in carpet industries have concerned environmental specialists. Among different treatment methods, membrane filtration processes as energy-efficient and compatible way, were utilized for several individual problems. In this research, novel hybrid membranes were prepared by waste fibers of mechanical carpets as useful resource of membrane matrix and industrial graphite powder as filler to eliminate Chrysophenine GX from dyeing wastewater. These membranes were expected to be utilized for first stage of hybrid membrane filtration process including (adsorption-ultrafiltration) and nanofiltration in Kashan Textile Company. For scaling of membrane filtration process, fouling mechanism of these membranes were recognized and explained by the use of genetic algorithm, as well. The graphite increased rejection and diminished permeate flux at low concentration but in high concentration, the performance was significantly worsened. Among all hybrid membranes, 18% wt. waste fibers-1% wt. graphite membrane had the best performance and minimum fouling. The maximum pore size of this optimum membrane was ranged from 16.10 to 18.72 nm.

• Biomedical Science Letters
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• v.17 no.2
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• pp.167-171
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• 2011

[ ${\alpha}$ ]synuclein (${\alpha}$-syn) is implicated in the pathogenesis of Parkinson's disease (PD) and other related diseases. We have previously reported that ${\alpha}$-syn binds to the cell membranes in a transient and reversible manner. However, little is known about the physiologic function and/or consequence of this association. Here, we examined whether chemically induced perturbations to the cellular membranes enhance the binding of ${\alpha}$-syn, based on hypothesis that ${\alpha}$-syn may play a role in maintenance of membrane integrity or repair. We induced membrane perturbations or alterations in ${\alpha}$-syn-overexpressing human neuroblastoma cells (SH-SY5Y) by treating the cells with hydrogen peroxide ($H_2O_2$) or oleic acid. In addition, membranes fractionated from these cells were perturbed by treating them with proteinase K or chloroform. Dynamic interaction of ${\alpha}$-syn to the membranes was analyzed by the chemical cross-linking assay that we developed in the previous study. We found that membrane interaction of ${\alpha}$-syn was increased upon treatment with membrane-perturbing reagents in a dose and time dependent manner. These results suggest that perturbations in the cellular membranes cause increased binding of ${\alpha}$-syn, and this may have significant implication in the physiological function of ${\alpha}$-syn in cells.

• Macromolecular Research
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• v.14 no.4
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• pp.438-442
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• 2006

Novel sulfonated poly(aryl ether ketones) containing benzoxazole were directly synthesized by aromatic nucleophilic polycondensation using various ratios of 2,2'-bi[2-( 4-flurophenyl)benzoxazol-6-yl]hexafluoropropane to sodium 5,5'-carbonylbis(2-fluorobenzenesulfonate). The copolymers were soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide at a relatively high solid composition (>15 wt%) and formed tough, flexible and transparent membranes. The membranes exhibited a degradation temperature of above $290^{\circ}C$. The exact dissolution times of these membranes at $80^{\circ}C$ in Fenton's reagent (3 wt% $H_2O_2$ containing 2 ppm $FeSO_4$) were undetectable, confirming their excellent chemical stability in fuel cell application. The membranes showed a moderate increase in water uptake with respect to increasing temperature. The proton conductivities of the membranes were dependent on the composition and ranged from $1.10{\times}10^{-2}$ to $5.50{\times}10^{-2}Scm^{-1}$ at $80^{\circ}C$ and 95% relative humidity (RH). At $120^{\circ}C$ without externally humidified conditions, the conductivities increased above $10^{-2}Scm^{-1}$ with respect to increasing benzoxazole content, which suggested that the benzoxazole moieties contributed to the proton conduction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.223-227
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• 2001

In this paper, the authors present the fabrication of high-yield Si thin-membranes by electrochemical etch-stop in tetramethyl ammonium hydroxide (TMAH): isopropyl alcohol (IPA):pyrazine solutions. The current-voltage (I-V) characteristics of n- and p-type Si in TMAH:IPA;pyrazine solutions were analysed, repsectively. Open circuit potential (OCP)and passivation potential (PP) of n- and p-type Si, respectively, were obtained and applied potential was selected between n- and p-type Si PPs. The electrochemical etch-stop method was applied to the fabrication of 801 micro-membranes with 20.0 $\mu\textrm{m}$ thickness on a 5" Si wafer. The average thickness of fabricated 801 micro-membranes on one wafer 20.03$\mu\textrm{m}$ and the standard deviation was ${\pm}$0.26$\mu\textrm{m}$. The Si surface of the etch-stopped micro-membranes was extremely flat with no noticeable taper or nonuniformity. The results indicate that use of the electrochemical etch-stop method for the etching of Si in TMAH:IPA;pyrazine solutions provides a powerful and versatile alternative process for fabricating high-yield Si micro-membranes.

• 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).

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.713-723
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• 2014

Biofouling in brackish water reverse osmosis (RO) membranes still needs extensive research to understand cause and mechanism and to obtain methods for reduction of its impact on RO applications. Natural compounds with biofilm formation inhibitory properties are being investigated. Two compounds, vanillin and Epigallocatechin gallate (EGCG), were selected due to their great potential on biofilm formation inhibition. Vanillin shows inhibition on quorum sensing mechanisms of biofilm formation. EGCG has potential to inactivate microbial activity. The two compounds were incorporated in typical polyamide reverse osmosis membranes and evaluated on flux behaviours and biofilm formation potential. The surface properties of membrane coated with vanillin were changed tremendously compared to those with EGCG. As a result, the flux was reduced substantially. The biofilm formation seems hindered with EGCG coated membranes compared to the virgin membranes. More research is needed to optimize coating methods applicable to RO membranes and to enhance biofouling reduction.