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Taishung Chung - One of the best experts on this subject based on the ideXlab platform.

  • Separation of vegetable oil compounds and solvent recovery using commercial organic solvent nanofiltration membranes
    Journal of Membrane Science, 2019
    Co-Authors: Gui Min Shi, Mohammad Hossein Davood Abadi Farahani, Jia Yu Liu, Taishung Chung
    Abstract:

    Abstract Solvent recovery and separation of oil compounds by means of thermal evaporation processes consume a huge amount of energy. Organic solvent nanofiltration (OSN) is an energy-efficient separation technique that can be potentially used for solvent recovery and separation of oil compounds in the vegetable oil industry. However, there are only a few studies on the separation of oil compounds using OSN. Almost no studies have been conducted on membrane fouling and long-term stability using highly concentrated oil/solvent feeds. This study explores the separation of oil compounds such as triglycerides and free fatty acids as well as solvent recovery using a series of Evonik commercial membranes. Under a static testing condition, the permeance of Duramem 500 reduces severely from 1.02 to 0.06 LMH/bar with an increase in oil concentration while its rejection to glyceryl trilinoleate decreases slightly from 86 to 84.8% when the feed concentration increases from 5 to 50 wt%. The severe permeance decline arises from the high viscosity of the permeate and oil layers accumulated on the membrane surface. In contrast, the membrane is able to separate glyceryl trilinoleate from linoleic acid with Permeances approximately 3–6 times of those obtained from the static testing mode under 1-week cross-flow tests using a 20 wt% oil/acetone feed.

  • high performance multiple layer pim composite hollow fiber membranes for gas separation
    Journal of Membrane Science, 2018
    Co-Authors: Can Zeng Liang, Jiangtao Liu, Juinyih Lai, Taishung Chung
    Abstract:

    Abstract The invention of polymers of intrinsic microporosity (PIMs) has opened up great opportunities for the developments of high-performance composite membranes which possess both high gas permeance and selectivity. However, it still remains challenging to translate such PIM materials into PIM-related composite membranes with characteristics of high permeance and selectivity. For the first time, we report defect-free PIM composite hollow fiber membranes that have pure O2 and CO2 Permeances of 69 and 483 GPU, respectively, and O2/N2 and CO2/N2 selectivities of 3.2 and 22.5, respectively. The O2/N2 and CO2/N2 selectivities are further increased to 4.2 and 29.5 respectively in air separation and flue gas tests. The composite hollow fiber membranes consist of three layers. The top selective-layer material is made from the nucleophilic substitution copolymerization between PIM and beta-cyclodextrin (β-CD) (referred to as PIM-CD), while the gutter and substrate materials are polydimethylsiloxane (PDMS) and polyacrylonitrile (PAN), respectively. The key to producing such composite membranes is to introduce a cross-linked PDMS gutter layer between the PIM-CD selective layer and PAN substrates that can (1) mitigate the detrimental solvent effects during the dip coating, (2) allow PIM to adhere on it, and (3) redistribute the gas transport across the membranes.

  • performance enhancement in organic solvent nanofiltration by double crosslinking technique using sulfonated polyphenylsulfone sppsu and polybenzimidazole pbi
    Journal of Membrane Science, 2018
    Co-Authors: Akbar Asadi Tashvigh, Taishung Chung, Lin Luo, Martin Weber, Christian Maletzko
    Abstract:

    Abstract In this paper, we report a new technique to design highly stable and selective organic solvent nanofiltration (OSN) membranes with enhanced solvent permeance by manipulating the crosslinking reactions. The new technique consists of three steps: (1) membrane fabrication via non-solvent induced phase inversion by blending sulfonated polyphenylsulfone (sPPSU) and polybenzimidazole (PBI) polymers, followed by (2) crosslinking the PBI part using α,α′-dibromo-p-xylene (DBX) to make the membrane chemically stable, and (3) ionically crosslinking the sPPSU part with hyperbranched polyethylenimine (HPEI) to narrow down the membrane pore size without affecting the permeance significantly. Crosslinking reactions have been confirmed by FTIR and XPS analyses. The OSN performance of the double crosslinked membranes was determined by measuring the permeance of various organic solvents and the rejection rates of tetracycline (Mw = 444 g mol−1) as a model pharmaceutical. Depending on the testing solvents, the Permeances ranged from 2 to 11.8 L m−2 h−1 bar−1, while the rejection rates of tetracycline varied from 67% to 97%. Considering the outstanding OSN performance and the great chemical stability in a wide range of solvent polarities, this novel double crosslinking technique represents a step forward in the fabrication of high performance OSN membranes.

  • cross linked mixed matrix membranes consisting of carboxyl functionalized multi walled carbon nanotubes and p84 polyimide for organic solvent nanofiltration osn
    Separation and Purification Technology, 2017
    Co-Authors: Mohammad Hossein Davood Abadi Farahani, Dan Hua, Taishung Chung
    Abstract:

    Abstract We have fabricated mixed matrix membranes (MMMs) consisting of carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) and P84 polyimide in this study for organic solvent nanofiltration (OSN) with the aid of chemical cross-linking by 1,6-hexanediamine (HDA). A moderate annealing is also used to manipulate the pore size for a better solute rejection. The incorporation of hydrophilic carbon nanotubes into P84 not only improves liquid sorption and transport but also increases membrane porosity and pore size. As a result, the Permeances of water, ethanol, and isopropanol across the MMMs increases with an increase in MWCNTs-COOH loading up to 0.075 wt.%. However, a higher loading of MWCNTs-COOH reduces the separation performance. The cross-linked MMM comprising 0.05 wt.% MWCNTs-COOH has a rejection of 85% to rose bengal (1017.65 Da) while ethanol permeance is 9.6 LMH⋅bar −1 at 5 bar. Interestingly, the rejection of rose bengal in isopropanol solutions is higher than that in ethanol solutions (i.e., 99 vs. 85%). After thermal annealing at 150 °C in a 3/1 EG/PEG400 (weight ratio) solution, the resultant membranes (MMM comprising 0.05 wt.% MWCNTs-COOH) show superlative rejections to small dye molecules (almost 100% to Safranin O dye molecules, 350.85 Da) in ethanol solutions. There is an obvious trade-off between rejection and permeance among the fabricated membranes, in which, the permeance enhancement and rejection diminishing occurred with the addition of MWCNTs-COOH; however, a vice-versa trend was observed in annealed membranes.

  • design of high efficiency pvdf peg hollow fibers for air filtration of ultrafine particles
    Journal of Membrane Science, 2017
    Co-Authors: Liangyi Wang, Wai Fen Yong, Liya E Yu, Taishung Chung
    Abstract:

    Abstract This study reveals as the first attempt to apply hollow fibers for air filtration of ultrafine particles. Different from symmetric nano-fiber filters and non-woven fabrics, asymmetric polyvinylidene fluoride – polyethylene glycol (PVDF-PEG) hollow fibers with high gas Permeances have been developed by the dry-jet wet-spinning process. The addition of high molecular weight PEGs in spinning dopes facilitates the formation of loosely connected cross-section and porous outer skin, thus enhances the gas permeance for air filtration. Under the inside-out testing mode, all PVDF-PEG hollow fibers display excellent filtration efficiency of 99.999% against polydispersed NaCl particles with a geometric mean size of ~30 nm. Since permeance increases with an increase in PEG molecular weight in spinning dope, the PVDF-PEG hollow fiber with a PEG molecular weight (MW) of 12,000 Da possesses the highest quality factor because it has the highest permeance and lowest transmembrane pressure. However, the PVDF-PEG hollow fiber with a PEG MW of 8000 Da has the best mechanical properties. Under the dead-end filtration, the filtration efficiency increases with an increase in air flow rate. This trend is contrary to the findings observed in the flat and symmetric fibrous filtration. The asymmetric structure in the cross-section of the newly developed hollow fibers may enhance aerosol deposition via direct impaction and Brownian motion at high flow rates. The dead-end filtration results also show that the quality factor is higher at a lower flow rate. Similarly, the cross-flow filtration results show that the hollow fiber modules operated at low cross-flow ratios have high quality factors. Therefore, it is preferred to operate the newly developed PVDF-PEG hollow fiber at a low flow rate or low cross-flow ratio. This study may provide useful insights for developing hollow fibers for air filtration with the optimal operation conditions.

Shigenori Fujikawa - One of the best experts on this subject based on the ideXlab platform.

  • critical role of the molecular interface in double layered pebax 1657 pdms nanomembranes for highly efficient co2 n2 gas separation
    ACS Applied Materials & Interfaces, 2020
    Co-Authors: Olena Selyanchyn, Roman Selyanchyn, Shigenori Fujikawa
    Abstract:

    In this work, we deposited a CO2-selective block copolymer, Pebax-1657, as a selective layer with a thickness of 2-20 nm on the oxygen plasma-activated surface of poly(dimethylsiloxane) (PDMS) used as a gutter layer (thickness ∼400 nm). This double-layered structure was subsequently transferred onto the polyacrylonitrile (PAN) microporous support and studied for CO2/N2 separation. The effect of interfacial molecular arrangements between the selective and gutter layers on CO2 permeance and selectivity has been investigated. We have revealed that the gas permeance and selectivity do not follow the conventional theoretical predictions for the multilayer membrane (resistance in series transport model); specifically, more selective CO2/N2 separation membranes were achieved with ultrathin selective layers. Detailed characterization of the chemical structure of the outermost membrane surface suggests that nanoscale blending of the ultrathin Pebax-1657 layer with O2 plasma-activated PDMS chains on the surface takes place. This nanoblending at the interface between the selective and gutter layers played a critical role in enhancing the CO2/N2 selectivity. CO2 Permeances in the developed thin-film composite membranes (TFCM) were between 1200 and 3500 gas permeance units (GPU) and the respective CO2/N2 selectivities were between 72 and 23, providing the gas separation performance suitable for CO2 capture in postcombustion processes. This interpenetrating polymer interface enhanced the overall selectivity of the membrane significantly, exceeding the separation ability of the pristine Pebax-1657 polymer.

  • thickness effect on co2 n2 separation in double layer pebax 1657 pdms membranes
    Membranes (Basel), 2018
    Co-Authors: Roman Selyanchyn, Miho Ariyoshi, Shigenori Fujikawa
    Abstract:

    The effect of thickness in multilayer thin-film composite membranes on gas permeation has received little attention to date, and the gas Permeances of the organic polymer membranes are believed to increase by membrane thinning. Moreover, the performance of defect-free layers with known gas permeability can be effectively described using the classical resistance in series models to predict both permeance and selectivity of the composite membrane. In this work, we have investigated the Pebax®-MH1657/PDMS double layer membrane as a selective/gutter layer combination that has the potential to achieve sufficient CO2/N2 selectivity and permeance for efficient CO2 and N2 separation. CO2 and N2 transport through membranes with different thicknesses of two layers has been investigated both experimentally and with the utilization of resistance in series models. Model prediction for permeance/selectivity corresponded perfectly with experimental data for the thicker membranes. Surprisingly, a significant decrease from model predictions was observed when the thickness of the polydimethylsiloxane (PDMS) (gutter layer) became relatively small (below 2 µm thickness). Material properties changed at low thicknesses—surface treatments and influence of porous support are discussed as possible reasons for observed deviations.

  • Thickness Effect on CO2/N2 Separation in Double Layer Pebax-1657®/PDMS Membranes
    MDPI AG, 2018
    Co-Authors: Roman Selyanchyn, Miho Ariyoshi, Shigenori Fujikawa
    Abstract:

    The effect of thickness in multilayer thin-film composite membranes on gas permeation has received little attention to date, and the gas Permeances of the organic polymer membranes are believed to increase by membrane thinning. Moreover, the performance of defect-free layers with known gas permeability can be effectively described using the classical resistance in series models to predict both permeance and selectivity of the composite membrane. In this work, we have investigated the Pebax®-MH1657/PDMS double layer membrane as a selective/gutter layer combination that has the potential to achieve sufficient CO2/N2 selectivity and permeance for efficient CO2 and N2 separation. CO2 and N2 transport through membranes with different thicknesses of two layers has been investigated both experimentally and with the utilization of resistance in series models. Model prediction for permeance/selectivity corresponded perfectly with experimental data for the thicker membranes. Surprisingly, a significant decrease from model predictions was observed when the thickness of the polydimethylsiloxane (PDMS) (gutter layer) became relatively small (below 2 µm thickness). Material properties changed at low thicknesses—surface treatments and influence of porous support are discussed as possible reasons for observed deviations

Richard W Baker - One of the best experts on this subject based on the ideXlab platform.

  • power plant post combustion carbon dioxide capture an opportunity for membranes
    Journal of Membrane Science, 2010
    Co-Authors: Timothy C Merkel, Richard W Baker
    Abstract:

    Abstract Carbon dioxide capture from power plant flue gas and subsequent sequestration is expected to play a key role in mitigating global climate change. Conventional amine technologies being considered for separating CO 2 from flue gas are costly, energy intensive, and if implemented, would result in large increases in the cost of producing electricity. Membranes offer potential as an energy-efficient, low-cost CO 2 capture option. Recently, working with the U.S. Department of Energy (DOE), we have developed membranes with CO 2 Permeances of greater than 1000 gpu and a CO 2 /N 2 selectivity of 50 at 30 °C. This permeance is ten times higher than commercial CO 2 membranes and the selectivity is among the highest reported for non-facilitated transport materials. These membranes, in combination with a novel process design that uses incoming combustion air as a sweep gas to generate driving force, could meet DOE CO 2 capture cost targets. Under these conditions, improving membrane permeance is more important than increasing selectivity to further reduce the cost of CO 2 capture from flue gas. Membrane cost and reliability issues will be key to the eventual competitiveness of this technology for flue gas treatment.

  • power plant post combustion carbon dioxide capture an opportunity for membranes
    Journal of Membrane Science, 2010
    Co-Authors: Timothy C Merkel, Richard W Baker
    Abstract:

    Abstract Carbon dioxide capture from power plant flue gas and subsequent sequestration is expected to play a key role in mitigating global climate change. Conventional amine technologies being considered for separating CO 2 from flue gas are costly, energy intensive, and if implemented, would result in large increases in the cost of producing electricity. Membranes offer potential as an energy-efficient, low-cost CO 2 capture option. Recently, working with the U.S. Department of Energy (DOE), we have developed membranes with CO 2 Permeances of greater than 1000 gpu and a CO 2 /N 2 selectivity of 50 at 30 °C. This permeance is ten times higher than commercial CO 2 membranes and the selectivity is among the highest reported for non-facilitated transport materials. These membranes, in combination with a novel process design that uses incoming combustion air as a sweep gas to generate driving force, could meet DOE CO 2 capture cost targets. Under these conditions, improving membrane permeance is more important than increasing selectivity to further reduce the cost of CO 2 capture from flue gas. Membrane cost and reliability issues will be key to the eventual competitiveness of this technology for flue gas treatment.

Shigeharu Morooka - One of the best experts on this subject based on the ideXlab platform.

  • gas permeation properties of ion exchanged faujasite type zeolite membranes
    Aiche Journal, 1999
    Co-Authors: Katsuki Kusakabe, Takahiro Kuroda, K Uchino, Yasuhisa Hasegawa, Shigeharu Morooka
    Abstract:

    NaY-type zeolite membranes were synthesized on a porous support tube by a hydrothermal process. The membranes were ion-exchanged with Li+ and K+ ions, and Permeances through the membranes were determined for an equimolar mixture of CO2 and N2, as well as for single-components thereof, at a temperature range of 0–400°C. The permeance to CO2 showed a maximum at 100°C, but CO2/N2 selectivity decreased with increasing temperature. The zeolite membranes that were exchanged with K+ and Li+ ions gave higher and lower CO2/N2 selectivities, respectively, than were found for the NaY-type membrane. The permeation properties of the ion-exchanged zeolite membranes were analyzed using a sorption–diffusion model. The high CO2/N2 selectivity of the K-exchanged membranes can be explained by the decrease in N2 sorptivity for the mixed feed.

  • separation of carbon dioxide from nitrogen using ion exchanged faujasite type zeolite membranes formed on porous support tubes
    Journal of Membrane Science, 1998
    Co-Authors: Katsuki Kusakabe, Takahiro Kuroda, Shigeharu Morooka
    Abstract:

    Abstract Faujasite-type zeolite membranes were reproducibly synthesized by hydrothermal reaction on the outer surface of a porous α -alumina support tube of 30 or 200 mm in length. The membrane properties were evaluated by CO 2 separation from an equimolar mixture of CO 2 and N 2 at a permeation temperature of 40°C. CO 2 permeance and CO 2 /N 2 selectivity of the NaY-type membranes were in the ranges of 0.4×10 −6 –2.5×10 −6  mol m −2  s −1  Pa −1 and 20–50, respectively. The NaY-type membranes were ion-exchanged with alkali and alkaline earth cations. The LiY-type membrane showed the highest N 2 permeance and the lowest CO 2 /N 2 selectivity. The KY-type membrane gave the highest CO 2 /N 2 selectivity. The NaY-type membrane was stable against exposure to air at 400°C. NaX-type zeolite membranes, formed by decreasing the ratio of SiO 2 /Al 2 O 3 in the starting solution, exhibited lower CO 2 Permeances and higher CO 2 /N 2 selectivities than those of the NaY-type zeolite membranes.

  • pore size control and gas permeation kinetics of silica membranes by pyrolysis of phenyl substituted ethoxysilanes with cross flow through a porous support wall
    Journal of Membrane Science, 1997
    Co-Authors: Katsuki Kusakabe, Shigeharu Morooka
    Abstract:

    Abstract A silica membrane was produced by chemical vapor deposition using tetraethoxysilane (TEOS), phenyltriethoxysilane (PTES) or diphenyldiethoxysilane (DPDES) as the Si source. Amorphous silica was deposited in the mesopores of a γ-alumina film coated on a porous α-alumina tube, by evacuating the reactant through the porous wall. Hydrogen permeance at a permeation temperature of 600°C was of the order of 10−7 mol m−2 s−1 Pa−1, and was not greatly dependent on the Si sources. The silica membrane produced using TEOS contained micropores permeable to both helium and hydrogen, but CO2 and larger molecules were only slightly permeated through those mesopores which were left unplugged. The silica membrane produced from DPDES showed a single-component CO2 permeance equivalent to that of single-component He, and CO 2 N 2 selectivity was approximately 9 at a permeation temperature of 30°C. When a mixture of CO2 and N2 was fed, however, CO2 permeance decreased to the level of N2 permeance. The H 2 N 2 selectivity, determined from single-component Permeances to H2 and N2, was approximately 100, and these Permeances remained unchanged when an equimolar mixture of H2 and N2 was fed. Thus, the DPDES-derived membrane possessed two types of micropores, abundant pores through which helium and hydrogen permeated and a small number of pores in which molecules of CO2 and N2 were permeable but not able to pass one another. Neither meso or macropores remained in the DPDES membrane.

  • formation of a y type zeolite membrane on a porous α alumina tube for gas separation
    Industrial & Engineering Chemistry Research, 1997
    Co-Authors: Katsuki Kusakabe, Takahiro Kuroda, And Atsushi Murata, Shigeharu Morooka
    Abstract:

    A porous α-alumina support tube, polished with a finely powdered X-type zeolite for use as seeds, was placed vertically in an autoclave containing an aqueous mixture of water glass and sodium aluminate. Hydrothermal synthesis was carried out at 90 °C for 24 h. A polycrystalline layer of Y-type zeolite was thus formed on the outer surface of the support tube. After washing and drying in air, Permeances of single components and mixtures of CO2 and N2, as well as CH4, C2H6, and SF6, were determined. The CO2 permeance was higher than that of N2 at temperatures of 30−130 °C. When an equimolar mixture of CO2 and N2 was fed into the feed side, the CO2 permeance was nearly equal to that for the single-component system and the N2 permeance for the mixture was greatly decreased, especially at lower permeation temperatures. This was due to selective adsorption of CO2 in subnanometer micropores of the membrane. At 30 °C, the permeance of CO2 was higher than 10-7 mol·m-2·s-1·Pa-1, and the permselectivity of CO2 to N2 ...

Timothy C Merkel - One of the best experts on this subject based on the ideXlab platform.

  • power plant post combustion carbon dioxide capture an opportunity for membranes
    Journal of Membrane Science, 2010
    Co-Authors: Timothy C Merkel, Richard W Baker
    Abstract:

    Abstract Carbon dioxide capture from power plant flue gas and subsequent sequestration is expected to play a key role in mitigating global climate change. Conventional amine technologies being considered for separating CO 2 from flue gas are costly, energy intensive, and if implemented, would result in large increases in the cost of producing electricity. Membranes offer potential as an energy-efficient, low-cost CO 2 capture option. Recently, working with the U.S. Department of Energy (DOE), we have developed membranes with CO 2 Permeances of greater than 1000 gpu and a CO 2 /N 2 selectivity of 50 at 30 °C. This permeance is ten times higher than commercial CO 2 membranes and the selectivity is among the highest reported for non-facilitated transport materials. These membranes, in combination with a novel process design that uses incoming combustion air as a sweep gas to generate driving force, could meet DOE CO 2 capture cost targets. Under these conditions, improving membrane permeance is more important than increasing selectivity to further reduce the cost of CO 2 capture from flue gas. Membrane cost and reliability issues will be key to the eventual competitiveness of this technology for flue gas treatment.

  • power plant post combustion carbon dioxide capture an opportunity for membranes
    Journal of Membrane Science, 2010
    Co-Authors: Timothy C Merkel, Richard W Baker
    Abstract:

    Abstract Carbon dioxide capture from power plant flue gas and subsequent sequestration is expected to play a key role in mitigating global climate change. Conventional amine technologies being considered for separating CO 2 from flue gas are costly, energy intensive, and if implemented, would result in large increases in the cost of producing electricity. Membranes offer potential as an energy-efficient, low-cost CO 2 capture option. Recently, working with the U.S. Department of Energy (DOE), we have developed membranes with CO 2 Permeances of greater than 1000 gpu and a CO 2 /N 2 selectivity of 50 at 30 °C. This permeance is ten times higher than commercial CO 2 membranes and the selectivity is among the highest reported for non-facilitated transport materials. These membranes, in combination with a novel process design that uses incoming combustion air as a sweep gas to generate driving force, could meet DOE CO 2 capture cost targets. Under these conditions, improving membrane permeance is more important than increasing selectivity to further reduce the cost of CO 2 capture from flue gas. Membrane cost and reliability issues will be key to the eventual competitiveness of this technology for flue gas treatment.