• Textile Coloration and Finishing
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• v.15 no.2
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• pp.68-75
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• 2003

In this work, ultrafiltration(UF) membranes were prepared using polyethersulfone(PES). The polymer was dissolved in various solvent, such as N, N-dimethyl formamide(DMF), N,-dimethyl acetamide (DMAc), N,N-dimethyl sulfoxide(DMSO) and N-methyl-2- pynolidone(NMP). Each polymer solution was casted on the glass plate, and immersed into non-solvent bath. In this way finely porous UF membranes were prepared by phase inversion method. The cross sectional structure of PES membrane was asymmetric which was consist of sponge-like sublayer, finger-like toplayer, and active skin layer. From the solute rejection experiments, the molecular weight cut off of the prepared membrane in various solvent was evaluated 10,000 for DMF, 30,000 for DMAc, 50,000 for DMSO, and 10,000 for NMP respectively.

• Korean Membrane Journal
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• v.5 no.1
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• pp.54-60
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• 2003

The rejection properties and flux rates of silica nanoparticles in ultrafiltration membranes has been investigated. Cross-flow permeation experiments were conducted using polycarbonate track-etch flat membranes with pore sizes of 30 and 50 nm, and a silica nanoparticle solute with particle sizes of 5 and 18 nm with narrow size distributions. The fluxes and rejection factors were investigated at various particle concentrations, cross-flow velocities, pH, and ionic strengths of solution. Even though the size of the silica nanoparticles was much smaller than that of the membrane pores, the observed rejection rates were very high compared with those for a similar-sized polymer (dextran). The observed rejection rate decreased with increasing ionic strength, which implies that the transport mechanism of the silica nanoparticles is significantly influenced by electrostatic repulsion between particles and membranes.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.199-203
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• 1992

This study was aimed to optimize the required condition for recovering the low soluble taste component obtained from sea tangle extract using ultrafiltration, and to investigate effects of membrane type, temperature, transmembrane pressure and flow rate respectively. We also compared relationship between the profile of permeate flux and the recovery yield of taste component under the selected optimal condition using ultrafiltration and diafiltration. Hydrophobic GR 51 PP membrane kept higher average permeate flux than hydrophilic FS membrane, and average permeate flux also had increasing tendency in relation to rising flow rate but it showed limit value of 3.7 l/min. Average permeate flux decreased as transmembrane pressure increased but it showed little change with rising temperature. Investigation upon average permeate flux, total dissolved solid and recovery yield of taste components using ultrafiltration and diafiltration resulted in relatively higher recovery yield in ultrafiltration. Compared ultrafiltration and diafiltration, average permeate flux was lower in ultrafiltration.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.171-178
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• 1991

The two-stage enzyme reactor, packed with cyclodextrin glucanotransferase (CGTase) immobilized on Amberite IRA 900, coupled with ultrafiltration membrane was investigated for continuous production of cyclodextrin (CD). 5% (w/v) of soluble starch was partially cyclized, in the 0.1 l first-stage immobilized enzyme reactor, up to CD conversion yield of 10% (w/w) at retention time of 0.56hr and 1.5 units of immobilized CGTase/1g of carrier. In the second stage main immobilized enzyme reactor capacity of 1.5 l, the maximum CD conversion yield of 39% (w/v) was achieved at retention time of 2.8hr and 0.47 unit of CGTase/1 g of carrier. Unreacted residual dextrin was fractionated with ultrafiltration membrane, and then, recycled into the second-stage main bioreactor to increase the CD conversion yield. The most suitable membrane size and the volume concentration ratio (concentrate: filterate) for recycling of unreacted residual dextrin were found to be 5K dalton and 4:6, respectively. CD conversion yield was increased about 3~4% upon co-immobilization of pulluanase along with CGTase. Spent Amberite IRA 900 can be reutilized consecutively more than 3 times for immobilization of CGTase after regeneration.

• Textile Coloration and Finishing
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• v.21 no.6
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• pp.56-63
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• 2009

In this study we have evaluated the separation characteristics and concentration of sericin using tubular type ultrafiltration membrane in silk degumming solution that extracted from electrolytic reduction water process. Ultrafiltration membranes have used in sericin separation performance and the separation characteristics of membrane satisfied typical Hagen-Poiseuille equation. It had the increase of flux according to the increase of feed pressure and temperature in occasion of pure water flux. And also the flux and solute rejection had about $25{\sim}60{\ell}/m^2{\cdot}h$ and more than 95% in sericin feed solution with concentration 1.00~1.89% at feed pressure force of $3{\sim}8kgf/cm^2$ respectively. In addition, the separation performance of tubular type ultrafiltration membrane for silk degumming solution was very steady-state with long experiment time.

• Membrane Journal
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• v.13 no.4
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• pp.211-218
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• 2003

The removal characteristics of cadmium in micellar enhanced ultrafiltration (MEUF) were investigated by using an anionic biosurfactant, deoxycholic acid (DCA). The ultrafiltration experiments were performed in a batch-type stirred cell. The ultrafiltration membranes used were Millipore YM1, YM3, YM10, and YM30 which had a difference in molecular weight cut-off. The presence of cadmium ion in DCA solution tends to reduce the critical micell concentration considerably and increase the micell size. The molecular weight cut-off of ultrafiltration membrane had a minimal effect on cadmium removal whereas DCA/Cd ratio had a substantial influence. When DCA/Cd ratio was 3, the removal efficiency of cadmium was more than 99.6%. A relative flux, which is defined as ratio of the flux for a separation trial to that of deionized water run using the same piece of membrane, decreased in the order of YM3 > YM1 > YM10 > YM30.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.04a
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• pp.6-10
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• 1995

An inevitable problem feature of membrane processing is concentration polarization (CF) which is a result of the accumulation of retained solutes at the membrane surface. In ultrafiltration (UF), this accumulation can lead to fouling due to the irreversible deposition of macromolecules both at the membrane surface and in the membrane pores. To reduce or control CP and folding, many possible methods have been considered [1]. One of the most effective approaches is to induce fluid instability near the membrane surface by using pusation flow [2, 3], Taylor [4] and Dean [5, 6] vortex flows. Winzeler and Belfort [6] have comprehensively reviewed several possible attempts to use fluid instabihties for improved membrane performance.

• Membrane Journal
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• v.28 no.1
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• pp.21-30
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• 2018

In this study, homogeneous and defect-free ceramic ultrafiltration membranes were fabricated by using the sol-gel method. A boehmite sol was synthesized and coated onto the surface of alumina hollow fiber microfiltration membranes. The effect of sol viscosity and surface tension on the coating layer homogeneity and thickness was investigated. The optimum coating repetition using pristine sol was determined to be 3 times, as the samples coated more than 4 times showed delamination. Fixing the coating repetition to 3 times, the effect of sintering temperature was also studied in this work. The samples sintered at $1000^{\circ}C$ exhibited the highest pure water permeability with the molecular weight cut-off (MWCO) of approximately 51 kDa (10 nm dextran), and the samples sintered at 600, $800^{\circ}C$ displayed the MWCO of 12 kDa (5 nm dextran). The ultrafiltration membranes prepared in this work showed competitive performance compared to the reported ceramic ultrafiltration membranes.

• Proceedings of the Membrane Society of Korea Conference
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• 2001.05a
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• pp.33-43
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• 2001

• Proceedings of the Membrane Society of Korea Conference
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• 1999.10b
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• pp.81-84
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• 1999