• Title/Summary/Keyword: Poly(vinyl alcohol) composite membranes

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Preparation of poly(vinyl alcohol)-coated Composite Nanofiltration Membranes on Various Support Membranes (다양한 지지체 분리막 위에 poly(vinyl alcohol)이 코팅된 나노복합막의 제조)

  • Lee Kew-Ho;Kim In-Chul
    • 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.

Bioelectricity Generation Using a Crosslinked Poly(vinyl alcohol) (PVA) and Chitosan (CS) Ion Exchange Membrane in Microbial Fuel Cell

  • Badillo-Cardoso Jonathan;Minsoo Kim;Jung Rae Kim
    • Journal of Electrochemical Science and Technology
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    • v.14 no.4
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    • pp.303-310
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    • 2023
  • Microbial fuel cells (MFCs) are a bioelectrochemical system where electrochemically active bacteria convert organic waste into electricity. Poly(vinyl alcohol) (PVA) and chitosan (CS) are polymers that have been studied as potential alternative ion exchange membranes to Nafion for many electrochemical systems. This study examined the optimal mixing ratio of PVA and chitosan CS in a PVA:CS composite membrane for MFC applications. PVA:CS composite membranes with 1:1, 2:1, and 3:1 ratios were synthesized and tested. The water uptake and ion exchange capacity, Fourier transform infrared spectra, and scanning electron microscopy images were analyzed to determine the physicochemical properties of PVA:CS membranes. The prepared membranes were applied to the ion exchange membrane of the MFC system, and their effects on the electrochemical performance were evaluated. These results showed that the composite membrane with a 3:1 (PVA:CS) ratio showed comparable performance to the commercialized Nafion membrane and produced more electricity than the other synthesized membranes. The PVA:CS membrane implemented MFCs produced a maximum power density of 0.026 mW cm-2 from organic waste with stable performance. Therefore, it can be applied to a cost-effective MFC system.

Nanofiltration Composite Membranes Based on Poly(vinyl alcohol) (폴리비닐알콜로 제조된 나노복합막)

  • 오남운;제갈종건;이규호
    • Proceedings of the Membrane Society of Korea Conference
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    • 1998.10a
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    • pp.106-108
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    • 1998
  • It has been proved by the study on nanofiltration with PVA dense membranes in our laboratory that the PVA is good material for the formation of chemically stable nanofiltration (NF) membranes. However, the PVA NF composite membranes prepared so far have rarely shown flux and rejection high enough for the commerciallyzation. The reasons for them would be the relatively thick thickness and improper crosslinking degree of the PVA active layers of the composite membranes. In this study, PVA composite membranes with improved nanofiltration properties have been prepared and characterized in terms of the morphology and permeation properties.

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Pervaporation Separation Characteristics for Water-Ethanol Mixtures Using Porous Hollow Fiber PVA Composite Membranes (미세 다공성 중공사 PVA복합막을 이용한 에탄올 수용액의 투과증발분리 특성)

  • Kim, Ji Seon;Park, Hun Whee;Seo, Chang Hee;Rhim, Ji Won
    • 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 $50^{\circ}C$.

Dehydration of Alcohol Solutions Through Crosslinked Chitosan Composite Membranes II. Dehydration of Ethanol Solution Through Modified Chitosan Composite Membranes (가교키토산 복합막을 통한 알콜수용액의 탈수 II. 변성 키토산 복합막을 통한 에탄올의 탈수)

  • 이영무;남상용;유제강;류경옥
    • Membrane Journal
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    • v.6 no.4
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    • pp.242-249
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    • 1996
  • To improve pervaporation performance of water/ethanol mixtures, chitosan/poly(vinyl alcohol) blended and phosphorylated chitosan composite membranes were prepared. Chitosan/poly(vinyl alcohol) blends were prepared with various blend ratios and then crosslinked with glutaraldehyde by two methods. With increasing crosslinking agent content and crosslinking times separation factor increased and permeate flux decreased. Separation factor of the membrane which contains glutaraldehyde as a crosslinking agent was higher than that of the membrane surface crosslinked. Phosphorylated chitosan was prepared with various reaction times and composite membrane was prepared. As reaction times increased, the separation factor increased with high affinity for water.

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Pervaporation Separation of fluoroethanol/water Mixtures through Crosslinked Poly(vinyl alcohol) Composite Membranes (가교된 폴리비닐알콜 복합막을 이용한 불화에탄올/물 혼합용액의 투과증발분리 특성)

  • 이수복;안상만;장봉준;김정훈;이용택
    • Membrane Journal
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    • v.14 no.2
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    • pp.166-172
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    • 2004
  • As a preliminary study for esterification membrane reactor used to produce 2,2,2-trifluoroethylmetacrylate (TFEMA), Pervaporation behaviors with crosslinked Poly(vinyl alcohol) composite membranes were investigated for aqueous TFEA (2,2,2-trifluoroethanol) feed solutions. In this study, crosslinked PVA composite membranes were prepared by reacting PVA with glutaraldehyde (CA)/acid catalyst onto porous polyethersulfone (PES) supports. SEH images (scanning electron microscopy) showed the thicknesses of selective coating layer was about 2-3 ${\mu}{\textrm}{m}$. The swelling tests showed the dogree of crosslinking decreased as content of the crosslinking agent, GA, increased. Total permeation flux decreased while separation factor increased as the CA content increased. As operating temperature increased, total permeation flux remarkably increased in the range of 85-95 wt% TFEA aqueous solutions. Interestingly, however, separation factor decreased in 85-90 wt% with operating temperature, while that increased in 95 wt%. In case of 90 wt% TFEA concentration and operating temperature 8$0^{\circ}C$, the PVA composite membrane crosslinked with 0.1 mol GA per PVA repeating unit showed high permeation flux of 1.5 kg/$m^2$hr and separation factor of 320. These results confirmed the applicability of the PVA composite membranes for the esterification membrane reactor of TFEMA.

Pervaporation of TFEA/MA/Water Mixtures through PVA Composite Membranes

  • Ahn, Sang-Man;Kim, Jeong-Hoon;Lee, Yong-Taek;Lee, Soo-Bok
    • Proceedings of the Membrane Society of Korea Conference
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    • 2005.11a
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    • pp.133-147
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    • 2005
  • In order to investigate applicability for 2,2,2-trifluoroethyl methacrylate (TFEMA) produced by esterification of 2,2,2-trifluoroethanol(TFEA) and methacrylic acid(MA) using pervaporation membrane, poly(vinyl alcohol) (PVA) composite membranes were prepared with glutaraldehyde(GA) onto porous polyethersulfone(PES) support. The degree of crosslinking and thickness of PVA coating layer were analyzed by swelling test and SEM(scanning electron microscopy), respectively. Pervaporation test was done with two feed mixures; TFEA/water, MA/water. The pervaporation data were obtained as a function of content of crosslinking agent, feed composition, and operating temperature, respectively. In case of TFEA-water(90/10 wt%) feed mixture at $80^{\circ}C$, the optimized membrane showed the high permeation flux of 1.5 $kg/m^2hr$ and separation factor of 320. In case of MA-water(90/10 wt%) feed mixture, the membranealso showed high permeation flux of 2.3 $kg/m^2hr$ and separation factor of 740 in same conditions.

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Ionic Cluster Mimic Membranes Using Ionized Cyclodextrin

  • Won Jong-Ok;Yoo Ji-Young;Kang Moon-Sung;Kang Yong-Soo
    • Macromolecular Research
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    • v.14 no.4
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    • pp.449-455
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    • 2006
  • Ionic cluster mimic, polymer electrolyte membranes were prepared using polymer composites of crosslinked poly(vinyl alcohol) (PVA) with sulfated-${\beta}$-cyclodextrins (${\beta}-CDSO_3H$) or phosphated-${\beta}$-cyclodextrins (${\beta}-CDPO(OH)_2$). When Nafion, developed for a fuel cell using low temperature, polymer electrolyte membranes, is used in a direct methanol fuel cell, it has a methanol crossover problem. The ionic inverted micellar structure formed by micro-segregation in Nafion, known as ionic cluster, is distorted in methanol aqueous solution, resulting in the significant transport of methanol through the membrane. While the ionic structure formed by the ionic sites in either ${\beta}-CDSO_3H$ or ${\beta}-CDPO(OH)_2$ in this composite membrane is maintained in methanol solution, it is expected to reduce methanol transport. Proton conductivity was found to increase in PVA membranes upon addition of ionized cyclodextrins. Methanol permeability through the PVA composite membrane containing cyclodextrins was lower than that of Nafion. It is thus concluded that the structure and fixation of ionic clusters are significant barriers to methanol crossover in direct methanol fuel cells.

Proton Conducting Behavior of a Novel Composite Based on Phosphosilicate/Poly(Vinyl Alcohol)

  • Huang, Sheng-Jian;Lee, Hoi-Kwan;Kang, Won-Ho
    • Journal of the Korean Ceramic Society
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    • v.42 no.2 s.273
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    • pp.77-80
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    • 2005
  • A series of proton conductive composite membranes based on poly(vinyl alcohol) and phosphosilicate gels powders were successfully prepared. The proton conductivity of these composite was attributed to the phosphosilicate gel, which derived from tetraethoxysilane and phosphoric acid by sol-gel process at a molar ratio of P/Si = 1.5. The proton conductivity increased with increasing both the content of phosphosilicate gel and relative humidity. Temperature dependence of conductivity showed a Vogel-Tamman-Fulcher type behavior, indicating that proton was transferred through a liquidlike phase formed in micropores of phosphosilicate gel. The high conductivity of 0.065 S/cm with a membrane containing 60 wt$\%$ of the gel was obtained at $60^{\circ}C$ at $90\%$ relative humidity.