• Membrane Journal
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• v.12 no.4
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• pp.255-261
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• 2002

Poly(vinyl alcohol) (PVA) membranes crosslinked with poly(acrylic acid-co-maleic anhydride) (PAM) as a polymeric crosslinking agent were prepared to investigate the pervaporation performance for the dehydration separation of aqueous ethanol solution. The characteristics of the resulting membranes crosslinked(x) were analysed by FT-IR and water swelling test. The water swelling decreased with increasing crosslinking agent content. The crosslinked PVA membranes with PAM showed lower water swelling than those of PVA membrane crosslinked with glutaraldehyde and modified PVA membrane. The swelling of water molecules in the crosslinked PVA membranes is more restricted by both chemical crosslinking between PVA and polymeric crosslinking agent chains and physical crosslinking by the entanglement between the PVA and polymeric crosslinking agent chains. For the pervaporation of aqueous ethanol solution through the crosslinked membrane, as the contents of crosslinking agent increased, the separation factor increased while the permeation flux decreased. The separation factor slightly decreased and permeation flux increased with increasing feed water content. As a result it could be considered that PVA-PAM membranes suppressed the plasticization effect even in the range of high water concentration in fled.

• Membrane Journal
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• v.6 no.4
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• pp.250-257
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• 1996

Surface crosslinked chitosan composite membranes were prepared with glutaraldehyde and surfuric acid. Effects of neutralization for complex between chitosan and acetic acid and of water permeability for substrate membranes on pervaporation performance were investigated. For ionically crosskinked membranes, effect of active layer thickness on separation factor of water/ethanol mixture was studied. With increasing the water permeability of the substrate, the membrane showed an increased separation factor, while it maintained a constant permeate flux. Neutralized chitosan composite membranes revealed a decreased separation factor and a constant permeate flux. When the thickness of the active layer increased, an optimum crosslinking time to achieve higher separation factor shifted to a prolonged times.

• Membrane Journal
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• v.18 no.1
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• pp.44-52
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• 2008

Pervaporation separation for water-ethanol mixtures has been carried out using crosslinked poly(vinyl alcohol) (PVA) membranes with poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA) and at which tetraethylorthosilicate (TEOS) was introduced. The concentration of PSSA_MA was fixed 7 wt% over PVA and the TEOS contents, 3, 5, and 7 wt%, were varied against PVA. The composition of the feed mixtures were 10, 20, 30 and 50 wt% of water in it. PVA/PSSA_MA/5 wt% TEOS membrane showed the separation factor, 1730 and the permeability, $16.3g/m^2{\cdot}hr$ for water : ethanol = 10 : 90 at $50^{\circ}C$.

• Membrane Journal
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• v.23 no.5
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• pp.360-366
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• 2013

The Poly (vinylidene fluoride) and poly (acrylonitrile) (PAN) hollow fiber composite membranes coated with poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) as the crosslinkig agent are prepared. The resulting membranes were characterized for aqueous 90 wt% ethanol solution by pervaporation techniques in terms of the permeability and separation factor. In general, as both the crsslinking reaction temperature and the crosslinking agent concentration increase, the permeability decrease while the separation factor tends to increase. And also the permeability increased and the separation factor decreased as the feed temperature increased. Typically, the permeability $502g/m^2hr$ at the feed temperature $70^{\circ}C$ was obtained for PVDF hollow fiber membrane prepared with the crosslinking agent PAA 3 wt% at the reaction temperature $60^{\circ}C$ whereas the separation factor 218 was shown for the membrane reacted with PAA 11 wt% and at $100^{\circ}C$ for the feed temperature $50^{\circ}C$.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.189-195
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• 2006

A study was conducted to develop optimal conditions for a large-scale, sequential separation method for value-added components from egg yolk. Starting with liquid egg yolk, immunoglobulin Y (IgY), phospholipids, and neutral lipids were extracted sequentially using water, ethanol, and n-hexane. The remainder was yolk proteins. Adjusting the pH of diluted egg yolk to pH 5.0-5.2 decreased phospholipids content in the supernatant after centrifugation, which was very important for preventing clogging problem of ultrafiltration filters during the subsequent concentration step for IgY separation. Extraction of precipitants after centrifugation with four volumes of 100% ethanol once removed most of the phospholipids and the purity of phospholipids was more than 85% (wt.) after drying. The subsequent extraction of precipitant from ethanol extraction with four volumes of hexane 3 times removed neutral lipids almost completely and resulted in a high protein product with minimal lipids. The sequential separation method is considered to be advantageous for large-scale separations of many valuable components from egg yolk.

• Journal of Industrial Technology
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• v.20 no.A
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• pp.179-184
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• 2000

The surface of porous alumina membrane was modified with silane coupling agent in order to enhance hydrophobicity. The contact angle of water to the surface-modified alumina membrane was greater than $90^{\circ}$. The surface-modified membrane was tested in vapor permeation for the concentration of aqueous ethanol. With the increase of ethanol concentration in the feed, permeation flux increased due to the greater affinity of ethanol with surface-modified alumina membrane than that of water. The experimental results showed that the permeation rate of surface-modified alumina membrane was 15~1000 times greater than that of polymer membranes.

• Proceedings of the Korean Fiber Society Conference
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• 1992.06a
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• pp.27-27
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• 1992

• Journal of Environmental Science International
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• v.9 no.4
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• pp.311-318
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• 2000

To improve $CO_2$pemselectivity, a modified silica membrane was prepared by chemical vapor deposition with tetraethoxysilane(TEOS)-ethanol-water, and TEOS-ethanol-water-HCI solution at 300-$600^{\circ}C$. The silica was effectively deposited in the mesopores of a ${\gamma}$-alumina film coated on a porous $\alpha$-alumina tube by evacuating the reactants through the porous wall. In this membrane, $CO_2$interacts, to some extent, with the pore wall, and $CO_2$/$N_2$selectivity then exceeds the value of the Knudsen diffusion mechanism, while the membrane derived from TEOS alone has no $CO_2$selectivity. The silica membrane prepared from TEOS-ethanol-water-HCI solution showed that $CO_2$permeance was $2.5$\times$10^{-7}mol/s^{-1}.m^{-2}.Pa^{-1} at 30{\circ}C$ and $CO_2$/$N_2$selectivity was approximately 3. The $CO_2$permeance and selectivity was improved by enlarging the surface diffusion with modification of chemical affinity of the silica pores.

• Macromolecular Research
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• v.11 no.3
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• pp.163-171
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• 2003

For the pervaporation of water-ethanol mixtures, new composite membranes having poly(acrylic acid)-poly (butyl methacrylate-co-methyl methacrylate) interpenetrati ng polymer network [PAA-P(BMA-co-MMA) IPN] skin layer supported on porous and crosslinked poly(BMA-co-MMA) were prepared. The morphology of the sub-layer of the composite membrane prepared in the presence of 60 wt% solvent showed cellular structure, on the other hand that of sublayer prepared in the presence of 70 wt% solvent presented very porous interconnected pore structure with macrovoids. Permeation rates of the composite membranes were largely influenced by the morphology of the sublayer. Separation factors increased with the increase of the degree of crosslinking of the PAA network. It was found that permeation rates could be increased by introducing anionic charges on carboxyl groups of the PAA. The permeation rate changes of the PAA-P(BMA-co-MMA) IPN composite membranes according to the feed compositions showed quite similar pattern with the swelling behavior in water-ethanol mixtures.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.469-474
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• 1998

Poly (vinyl alcohol) (PVA) membranes crosslinked with poly (styrene-co-maleic anhydride) (PSMAn) have been prepared by the solution method. To investigate the separation behavior of the crosslinked PVA/PSMAn membranes in the pervaporation process, the selective sorption experiment and swelling measurements of the membranes in ethanol-water mixtures of 30~90 wt % ethanol contents were conducted with equipment that was able to measure the concentration and amount of the liquid absorbed in the membranes. The membranes prepared in this study exhibited good selectivity toward water component in sorption and permeation. Also, in the feed containing ethanol more than 50 wt %, the permeation selectivity of the membrane showed better correlation with the sorption selectivity than that with the swelling ratio changing toward the crosslinking content. This behavior was consistence with a solution-diffusion model correlating permeation and sorption selectivity, and led to the conclusion that the permeation selectivity was determined by sorption step rather than by diffusion step in the membrane.