• Title/Summary/Keyword: alumina membrane

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Change of Phase Transformation and Microstructure of Alumina Membrane: I. Effect by Porosity of Support (알루미나 여과막의 상전이와 미세구조 변화: I. 지지체의 기공율에 의한 영향)

  • Cheong, Hun;Hwang, Kwang-Taek;Choi, Duck-Kyun;Cheong, Deock-Soo
    • Korean Journal of Materials Research
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    • v.12 no.3
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    • pp.205-210
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    • 2002
  • The HPS(High Porosity Support, 39.3%) and the LPS( Low Porosity Support, 18.7%) were fabricated to investigate the phase transformation and the chance of microstructure with porosity of alumina support. Alumina sol was made using aluminum tri-sec $butoxide(ATSB,\; Al(O-Bu)_3)$, the membrane on porous support with different porosity and the membrane without support were fabricated. The $\theta$-to ${\alpha}-A1_2O_3$ phase transformation in the membranes was investigated using thin film X-ray diffraction (XRD), and the change of microstructure was observed using scanning electron microscopy(SEM). XRD patterns showed that the membrane on LPS and HPS had 10$0^{\circ}C$, 5$0^{\circ}C$ higher $\theta$-to ${\alpha}-A1_2O_3$ transformation temperature compared to the unsupported membrane. A similar effect was also observed in microstructure of the membranes, theoritical temperature difference were 97$^{\circ}C$ and 44$^{\circ}C$ by Crapeyron equation.

Composite TiN-Al2O3 Syntheses and Hydrogen Permeability Characteristics Evaluation (복합 TiN-Al2O3 합성과 수소투과도 특성 평가)

  • CHO, KYOUNG-WON;LEE, YOUNG-HWAN;HAN, JEONG-HEUM;YU, JE-SEON;HONG, TAE-WHAN
    • Journal of Hydrogen and New Energy
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    • v.31 no.2
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    • pp.177-183
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    • 2020
  • To utilize hydrogen energy, high-yield, high-purity hydrogen needs to be produced; therefore, hydrogen separation membrane studies are being conducted. The membrane reactor that fabricates hydrogen needs to have high hydrogen permeability, selective permeability, heatresistant and a stable mechanical membrane. Dense membranes of Pd and Pd alloys are usually used, but these have drawbacks associated with high cost and durability. Therefore, many researchers have studied replacing Pd and Pd alloys. Dense TiN membrane is highly selective and can separate high-purity hydrogen. The porous alumina has a high permeation rate but low selectivity; therefore, separating high-purity hydrogen is difficult. To overcome this drawback, the two materials are combined as composite reclamations to produce a separation membrane with a high penetration rate and high selectivity. Accordingly, TiN-alumina was manufactured using a high-energy ball mill. The TiN-alumina membrane was characterized by X-ray diffraction analysis, scanning electron microscopy, and energy dispersive spectroscopy. The hydrogen permeability of the TiN-alumina membrane was estimated by a Sievert-type hydrogen permeation membrane apparatus. Due to the change in the diffusion mechanism, the transmittance value was lower than that of the general TiN ceramic separator.

Synthesis and Characterization of Sol-Gel Derived Mesoporous Titania/Alumina Membranes (솔젤법에 의한 메조기공 티타니아/알루미나 막의 제조 및 기체투과 특성)

  • Kwon, Hyuk-Taek;Kim, Jin-Soo
    • Membrane Journal
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    • v.21 no.3
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    • pp.229-235
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    • 2011
  • In this study, mesoporous titania/alumina membranes were prepared by sol-gel method. Pore structure and phase composition of titania/alumina membranes could be changed by calcination temperature. The addition of alumina into titania membranes retarded anatase-to-rutile phase transformation, resulting in stabilization of pore structures. The 5 time dip-coated membrane calcined at $450^{\circ}C$ is about $10.3{\mu}m$ in thickness with an average pore size of 5 nm. Hydrogen and nitrogen permeances through the membrane were $17.1{\times}10^{-7}mol/m^2{\cdot}s{\cdot}Pa$ and $4.7{\times}10^{-7}mol/m^2{\cdot}s{\cdot}Pa$, respectively. These data were explained by the Knudsen diffusion mechanism.

Vapor Permeation of Aqueous Ester Solutions Through Surface-modified Alumina Membrane (표면 개질한 알루미나막을 통한 ester 수용액의 증기 투과)

  • 오한기;송근호;이광래
    • Membrane Journal
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    • v.10 no.4
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    • pp.186-191
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    • 2000
  • The recovery of three ethyl esters (aroma model compounds; ethyl acetate, ethyl propionate. ethyl butyrate) from aqueous solutions was studied for vapor permeation with surface-modified hydrophobic alumina membrane, Although the driving force of ethyl butyrate is the highest, the ethyl butyrate concentration in permeate is lower than those of propionate and acetate. Since the solubility of aroma compounds for water is very low, phase separation occurred in permeate, and we could obtain pure ethyl esters. The experimental results showed that the porous hydrophobic alumina membrane had high selectivity and permeation flux on the ester-model compounds.

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Preparation and Characterization of α-alumina Hollow Fiber Membrane (알루미나 중공사막 제조 및 특성 분석)

  • Che, Jin Woong;Lee, Hong Joo;Park, Jung Hoon
    • Membrane Journal
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    • v.26 no.3
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    • pp.212-219
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    • 2016
  • The alumina hollow fiber membranes were prepared by spinning and sintering a polymer solution containing suspended alumina powders. For determine pore structure of hollow fiber membranes formed by different solvent-nonsolvent interaction rate, dimethylsulfoxide (DMSO), dimethylacetamide (DMAc), triethylphosphite (TEP) were prepared in dope solution by solvent, polyethersulfone (PESf) and polyvinylpyrrolidone (PVP) were used as a polymer binder and additive. The pore structure of hollow fiber membranes was characterized using scanning electron microscope (SEM). The alumina hollow fiber membranes prepared by DMSO, DMAc were had the asymmetric structure mixed sponge-like and finger-like morphology, while TEP solvent were had single sponge-like structure. The prepared hollow fiber membranes were analyzed gas permeation and mechanical strength experiment also. The hollow fiber membrane having single sponge-like structure was had high gas permeation performance. On the contrary to this, more finger-like morphology was less gas permeation performance.

Preparation of Inorganic Ultrafiltration Membrane by Anodic Oxidation in Oxalic Acid (수산전해액하에서 양극산화에 의한 무기 UF막의 제조)

  • Lee, Chang-Woo;Hong, Young-Ho;Chang, Yoon-Ho;Hahm, Yeong-Min
    • Applied Chemistry for Engineering
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    • v.9 no.4
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    • pp.536-541
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    • 1998
  • The porous size alumina membrane was prepared by anodic oxidation with current method in an aqueous solution of oxalic acid. The aluminum metal plate was pretreated with thermal oxidation, chemical polishing and electropolishing before anodic oxidation. Membrane thickness and pore size distribution were investigated with several anodizing conditions; reaction temperature, cumulative charge, electrolyte concentration and current density. The porous alumina membrane obtained was $55{\sim}75{\mu}m$ thick with straight micropore of 45~100nm. Also, the porous alumina membrane has an uniform pore diameter and pore distribution. It was inorganic ultrafiltration membrane as a kind of the ceramic membrane.

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Improvement in Mechanical Strength of α-Alumina Hollow Fiber Membrane by Introducing Nanosize γ-Alumina Particle as Sintering Agent (소결조제로 나노크기 γ-알루미나 입자의 도입에 따른 α-알루미나 중공사 분리막의 기계적 강도 향상)

  • Kim, Yong-Bin;Kim, Min-Zy;Arepalli, Devipriyanka;Cho, Churl-Hee
    • Membrane Journal
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    • v.32 no.2
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    • pp.150-162
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    • 2022
  • In the field of water treatment and pharmaceutical bio an alumina hollow fiber membrane used for mixture separation. However, due to the lack of strengths it is very brittle to handle and apply. Therefore, it is necessary to study and improve the bending strength of the membrane to 100 MPa or more. In this study, as the mixing ratio of the nano-particles increased to 0, 1, 3, and 5 wt%, the viscosity of the fluid mixture increased. The pore structure of the hollow membrane produced by interrupting the diffusion exchange rate of the solvent and non-solvent during the spinning process suppresses the formation of the finger-like structure and gradually increases the ratio of the sponge-like structure to improve the membrane mechanical strength to more than 100 MPa. As a result, an interparticle space was ensured to improve the porosity of the sponge-like structure with high permeability, and it showed excellent N2 permeability of about 100000 GPU and high water permeability of 3000 L/m2 h. Therefore, it can be concluded, that the addition of γ-Al2O3 nanoparticles as sintering aid is an important method to enhance the mechanical strength of the α-alumina hollow fiber membrane to maintain high permeability.

Novel Fabrication of Nanoporous Alumina Membrane Microtubes: 2-Dimensional Nanoporous Arrays on Every Facets of Microtubes

  • Chae, Weon-Sik;Im, Sung-Jae;Lee, Jin-Kyu;Kim, Yong-Rok
    • Bulletin of the Korean Chemical Society
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    • v.26 no.3
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    • pp.409-412
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    • 2005
  • Free-standing nanoporous alumina membrane microtubes with different shapes (rectangular and cylindrical tubes) and variable dimensions were easily fabricated by direct anodization of the aluminum templates of the specified shapes (strip and wire) and dimensions during the electrochemical reaction.

The Study on Surface Modification of Alumina Membrane by CVD (CVD에 의한 알루미나 멤브레인의 표면개질에 관한 연구)

  • 이동호;최두진;현상훈;고광백
    • Journal of the Korean Ceramic Society
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    • v.32 no.12
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    • pp.1349-1356
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    • 1995
  • The change of permeation mechanism from Knudsen diffusion to micropore diffusion was observed after CVD modification of an alumina-sol coated alumina support which was prepared by slip coating process. Permselectivities of He/N2, H2/N2, and CO2/N2 were 5.67, 5.02, and 1.44, respectively. These values were higher than those under Knudsen diffusion controlled region.

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THE PREPARTION AND CHAEATERIZATION OF ALUMINA UF MEMBRANE BY SOL-GEL PROCESS

  • Choi, Y. H.;Paik, J. S.;Kim, H. C.;Lee, S. B.;Oh-kim, E. O.
    • Proceedings of the Membrane Society of Korea Conference
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    • 1991.10a
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    • pp.29-33
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    • 1991
  • Alumina UF membranes were prepared by sol-gel process and their gas permeabilities were characterized. Alumina MF membrane with average pore diameter about 0.12$\mu$m and tubular shape was used as a support. Gas permeation measurements of helium and nitrogen gas exhibited the permeabilities of 1.58 $\times$ 10E-6 and $0.63 \times 10E-6 cc\cdot cm(STP)/cm^2\cdot sec \cdot cmHg$, respectively. The permeability ratio was 2.5. This means the gas permeation is fully governed by knudsen diffusion mechanism.

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