• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.155-160
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• 2004

Permeation experiments of a commercial nanofiltration membrane (nominated as ESNA 1) were carried out with aqueous solutions of various single salts, that is, five chlorides (NH$_4$Cl, NaCl, KCl, MgCl$_2$ and $CaCl_2$), three nitrates $(NaNo_3,\;Mg(No_3)_2\;and\;Ca(NO_3)_2)\;and\;three\;sulfates\;((NH_4)_2SO_4,\;Na_2SO_4\;and\;MgSO_4)$. The experimental results showed that (1) the permeate volume flux of the ESNA 1 membrane increased and decreased with the growth of the applied pressure and the feed concentration of salts, respectively. The real rejection of ESNA 1 membrane to most single salts increased with the growth of the permeate volume flux. (2) The reflection coefficients of ESNA 1 membrane to chlorides, nitrates and sulfates are 0.97, 0.96 and 0.99, respectively. The solute permeability of most salts except for magnesium and calcium salts increased with the growth of feed concentration. (3) The sequence of the rejections of ESNA 1 membrane to anions is $R({SO_4}^{2-})>R(CI)>R(NO_3)$ at the same feed concentration. While the sequence of the rejections to cations is cataloged into two cases: $R(Na^+)>R(K^+)>R(Mg^{2+})>R(Ca^{2+})$ at the concentration of 10 mol/$m^3$ and $R(Mg^{2+})>R(Ca^{2+})>R(Na^+)>R(K^+)$ at the concentration of 100 mol/$m^3$. The separation capability of a NF membrane is usually affected by the electrostatic effect and the steric-hindrance effect. In this case, the electrostatic effect is the major factor at low concentration and the steric-hindrance effect is the major factor at high concentration. Both the specific sorption and the hydration also reasonably influenced the separation performance of NF membrane to salts.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.94-97
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• 2004

Micro/nano-sized L $a_{0.6}$S $r_{0.4}$Co $O_{3-}$$\delta$/ particles are considered to improve oxygen permeability in highly selective inorganic oxygen separation membrane. A L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membrane with perovskite structure is fabricated by a conventional solid-state reaction. As the oxygen permeation flux of the L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membrane was lower than commercial gas separation membranes, we coated the L $a_{0.6}$S $r_{0.4}$Co $O_{3-}$$\delta$/ particles to enhance the oxygen permeation flux. It has been demonstrated that the effective area of reactive free surface is an important factor in determining the effectiveness of the introduction of coating layer for oxygen permeation. The introduction of micro/nano L $a_{0.6}$S $r_{0.4}$Co $O_{3-}$$\delta$/ particles was very effective for increasing oxygen flux, as the flux was as much as 2 to 6 times higher than that of an uncoated L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membrane.\delta$/ membrane.>/ membrane.brane.

• Membrane and Water Treatment
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• v.6 no.2
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• pp.141-160
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• 2015

This study aims to investigate the impacts of chemical cleaning on the performance of a reverse osmosis membrane. Chemicals used for simulating membrane cleaning include a surfactant (sodium dodecyl sulfate, SDS), a chelating agent (ethylenediaminetetraacetic acid, EDTA), and two proprietary cleaning formulations namely MC3 and MC11. The impact of sequential exposure to multiple membrane cleaning solutions was also examined. Water permeability and the rejection of boron and sodium were investigated under various water fluxes, temperatures and feedwater pH. Changes in the membrane performance were systematically explained based on the changes in the charge density, hydrophobicity and chemical structure of the membrane surface. The experimental results show that membrane cleaning can significantly alter the hydrophobicity and water permeability of the membrane; however, its impacts on the rejections of boron and sodium are marginal. Although the presence of surfactant or chelating agent may cause decreases in the rejection, solution pH is the key factor responsible for the loss of membrane separation and changes in the surface properties. The impact of solution pH on the water permeability can be reversed by applying a subsequent cleaning with the opposite pH condition. Nevertheless, the impacts of solution pH on boron and sodium rejections are irreversible in most cases.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.89-92
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• 2020

Polytetrafluoroethylene (PTFE) fibers are widely used in the textile industry, filter media, membrane distillation, electronic appliances, and construction. In this study, PTFE-polyethylene oxide (PEO) fibrous membranes were fabricated by emulsion electrospinning; subsequently, pure PTFE nanofibers were obtained via sintering. PTFE-PEO electrospinning solutions were prepared using different weight ratios to determine the optimized condition. As the ratio of the PEO increased, the fiber structure improved. Scanning electron microscopy and Fourier-transform infrared spectroscopy observations indicate that PEO is removed and PTFE fused gradually to form bonds among them during sintering. The obtained pristine PTFE membrane demonstrated hydrophobicity at 143.6° water contact angle and oleophilicity at 0° oil contact angle, which is known to be utilized for oil/water separation. A simple separation experiment was performed to remove oil droplets from water. The PTFE membrane exhibited good chemical stability and a high surface-area-to-volume nanofiber ratio. These excellent properties suggest that it is applicable to oil/water separation in harsh chemical environments.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.83-84
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• 1997

1. INTRODUCTION : Polyimides containing siloxane moiety(poly(imide siloxane), or polysiloxaneimide) have been synthesized because of their some merits over polyimide itseft. Polyimides have excellent thermal and mechanical properties but their poor solubility and processibility in their fullly imidized form give disadvantages in applications. Incorporation of siloxane units make it possible to increase solubility and processibility, and also impart impact resistance, low moisture uptake, low dielectric constant, thermo-oxidative resistance, good adhesion properties to substrate and etc.. Incorporation methods of siloxane groups into the polyimide was mainly copolymerization or terpolymerization between oligomeric dimethylsiloxane and aromatic dianhydride. A few methods of introducing siloxane units in functional groups of polyimide was reported. In our laboratory poly(amideimide siloxane) and poly(imide siloxane) were prepared and the study about their thermal kinetics was performed. In separation membrane area, polysiloxaneimides was utilized in pervaporation and gas separation. Polyimides in gas separation show high selectivity and very low permeability, and introduction of siloxane segments increase permeability with low decrease in selectivity. We aimed to introduce silicone segments into poly(amic acid) state and synthesize polymer partially imidized, and also show the gas separation characteristics of the synthesized polymer.

• Membrane Journal
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• v.2 no.2
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• pp.135-143
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• 1992

Separation of $N_2-SO_2$ mixed gas by polymer membranes, SEPA-97(CA), TFC, and FT-30 membrane, was investigated by varying pressure and temperature. The permeability coefficients and the separation factors of mixed gases were measured, and the influence of various factors on the gas permeability characteristics and separation performance were investigated. The range of pressure was 0.1~1.0 MPa, and that of temperature was 283~303 K. The experimental results showed that the permeability coefficients and the separation factors were increased with an increase in pressure, but they were deereased with increasing temperature. Among the examined membranes, FT-30 possessed the best gas-separating characteristics.

• Proceedings of the Membrane Society of Korea Conference
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• 2002.05a
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• pp.9-19
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• 2002

No Abstract, See Full-text

• Proceedings of the Membrane Society of Korea Conference
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• 1996.06a
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• pp.33-89
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• 1996

History of Membrane Process Development 1920 : microfiltration : Zsigmondy 1930 : ultrafiltration 1950 : hemodialysis : Kolff 1955 : electrodialysis 1960 : reverse osmosis : Loeb, sourirajan 1960 : ultrafiltration 1979 : gas separation : Henis, Tripodi 1982 : pervaporation : Tusel

• Proceedings of the Membrane Society of Korea Conference
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• 2003.11a
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• pp.193-196
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• 2003

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.12-12
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• 2004

A brief introduction was given in this paper for the research and development on membrane science and technology in China. Ion exchange membranes and electrodialysis, MF, UF, NF and RO membranes, gas separation (GS) membranes, pervaporation (PV), membranes, inorganic membranes (IM) and membrane reactors (MR) were involved.(omitted)