Fabrication of Self-Supporting Geopolymer Membranes and Gas Permeation through the Membranes

Porous membrane of poly(tetrafluoroethylene) (PTFE) was formed on the surface of porous ceramic tubes by means of heat treatment of the PTFE particles deposit layer prepared by filtering PTFE microparticles emulsified in aqueous phase. By means of inert gas permeation, pore size was determined and compared with scanning electron micrograph observation. Also rejection measurement of aqueous dextran solutions of wide range of molecular weights showed consistent results regarding the pore size. Since the membrane prepared by this method is stable and has unique features derived from PTFE, it is expected that the membrane has interesting applications in the field of water treatment. Membrane separation of activated sludge by this composite membrane and original ceramics membrane showed that the PTFE membrane gives better detachability of the cake layer formed on the membrane. This might be due to the hydrophobic nature of the PTFE skin layer.

Download Full-text

Gas Permeation Properties of High-Silica CHA-Type Zeolite Membrane

Membranes ◽

10.3390/membranes11040249 ◽

2021 ◽

Vol 11 (4) ◽

pp. 249

Author(s):

Yasuhisa Hasegawa ◽

Chie Abe ◽

Mayumi Natsui ◽

Ayumi Ikeda

Keyword(s):

Molecular Size ◽

Gas Permeation ◽

Zeolite Membrane ◽

Type Zeolite ◽

High Silica ◽

Separation Of Co2 ◽

Α Al2o3 ◽

Separation Performances ◽

Molecular Sieving ◽

Permeation Properties

The polycrystalline CHA-type zeolite layer with Si/Al = 18 was formed on the porous α-Al2O3 tube in this study, and the gas permeation properties were determined using single-component H2, CO2, N2, CH4, n-C4H10, and SF6 at 303–473 K. The membrane showed permeation behavior, wherein the permeance reduced with the molecular size, attributed to the effect of molecular sieving. The separation performances were also determined using the equimolar mixtures of N2–SF6, CO2–N2, and CO2–CH4. As a result, the N2/SF6 and CO2/CH4 selectivities were as high as 710 and 240, respectively. However, the CO2/N2 selectivity was only 25. These results propose that the high-silica CHA-type zeolite membrane is suitable for the separation of CO2 from CH4 by the effect of molecular sieving.

Download Full-text

Dependence of gas permeation and adsorption on temperature in vacuum insulation panels (VIPs) containing getter materials

Journal of Building Physics ◽

10.1177/17442591211017154 ◽

2021 ◽

pp. 174425912110171

Author(s):

Hideya Yamamoto ◽

Daisuke Ogura

Keyword(s):

Glass Fiber ◽

Adsorption Mechanism ◽

Gas Adsorption ◽

Gas Permeation ◽

Fiber Core ◽

Vacuum Insulation ◽

Calculation Results ◽

Long Term Performance ◽

Term Performance

Vacuum insulation panels (VIPs) with a glass-fiber core has been considered to be difficult to operate for a long period of time, such as for building applications, because the thermal conductivity rises rapidly as the pressure increases. However, glass-fiber-core VIPs contain a material called a getter that continuously adsorbs permeated gas, and a theoretical model that considers the properties of the getter has not yet been developed. In this paper, the gas-adsorption mechanism by getters was investigated and a long-term-performance prediction model that considers the temperature dependence was proposed. Some gases were not adsorbed by the getter in the VIPs; however, a model was proposed that takes into account the non-absorbed gases by applying partial pressure to the adsorption isotherm in advance. The long-term performance of VIPs with different areas and volumes was compared with the measured values, and the validity of the calculation results was confirmed. These results show that the long-term performance of VIPs of different sizes can be accurately predicted when the getter performance is well understood.

Download Full-text

Miscible blend polyethersulfone/polyimide asymmetric membrane crosslinked with 1,3-diaminopropane for hydrogen separation

Journal of Polymer Engineering ◽

10.1515/polyeng-2020-0316 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Nur’ Adilah Abdul Nasir ◽

Ameen Gabr Ahmed Alshaghdari ◽

Mohd Usman Mohd Junaidi ◽

Nur Awanis Hashim ◽

Mohamad Fairus Rabuni ◽

...

Keyword(s):

Separation Efficiency ◽

Chemical Characterization ◽

Gas Permeation ◽

Separation Performance ◽

Membrane Composition ◽

Asymmetric Membrane ◽

Wet Phase Inversion ◽

Pair Performance ◽

Improved Performance ◽

Physical And Chemical

Abstract Efficient purification technology is crucial to fully utilize hydrogen (H2) as the next generation fuel source. Polyimide (PI) membranes have been intensively applied for H2 purification but its current separation performance of neat PI membranes is insufficient to fulfill industrial demand. This study employs blending and crosslinking modification simultaneously to enhance the separation efficiency of a membrane. Polyethersulfone (PES) and Co-PI (P84) blend asymmetric membranes have been prepared via dry–wet phase inversion with three different ratios. Pure H2 and carbon dioxide (CO2) gas permeation are conducted on the polymer blends to find the best formulation for membrane composition for effective H2 purification. Next, the membrane with the best blending ratio is chemically modified using 1,3-diaminopropane (PDA) with variable reaction time. Physical and chemical characterization of all membranes was evaluated using field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR). Upon 15 min modification, the polymer membrane achieved an improvement on H2/CO2 selectivity by 88.9%. Moreover, similar membrane has demonstrated the best performance as it has surpassed Robeson’s upper bound curve for H2/CO2 gas pair performance. Therefore, this finding is significant towards the development of H2-selective membranes with improved performance.

Download Full-text

Integration of Stable Ionic Liquid-Based Nanofluids into Polymer Membranes. Part II: Gas Separation Properties toward Fluorinated Greenhouse Gases

Nanomaterials ◽

10.3390/nano11030582 ◽

2021 ◽

Vol 11 (3) ◽

pp. 582

Author(s):

Fernando Pardo ◽

Sergio V. Gutiérrez-Hernández ◽

Carolina Hermida-Merino ◽

João M. M. Araújo ◽

Manuel M. Piñeiro ◽

...

Keyword(s):

Ionic Liquid ◽

Gas Separation ◽

Value Added ◽

Gas Permeation ◽

Mixed Matrix Membranes ◽

Separation Performance ◽

Mixed Gas ◽

Neat Polymer ◽

Stable Suspension ◽

Base Polymer

Membrane technology can play a very influential role in the separation of the constituents of HFC refrigerant gas mixtures, which usually exhibit azeotropic or near-azeotropic behavior, with the goal of promoting the reuse of value-added compounds in the manufacture of new low-global warming potential (GWP) refrigerant mixtures that abide by the current F-gases regulations. In this context, the selective recovery of difluorometane (R32, GWP = 677) from the commercial blend R410A (GWP = 1924), an equimass mixture of R32 and pentafluoroethane (R125, GWP = 3170), is sought. To that end, this work explores for the first time the separation performance of novel mixed-matrix membranes (MMMs) functionalized with ioNanofluids (IoNFs) consisting in a stable suspension of exfoliated graphene nanoplatelets (xGnP) into a fluorinated ionic liquid (FIL), 1-ethyl-3-methylpyridinium perfluorobutanesulfonate ([C2C1py][C4F9SO3]). The results show that the presence of IoNF in the MMMs significantly enhances gas permeation, yet at the expense of slightly decreasing the selectivity of the base polymer. The best results were obtained with the MMM containing 40 wt% IoNF, which led to an improved permeability of the gas of interest (PR32 = 496 barrer) with respect to that of the neat polymer (PR32 = 279 barrer) with a mixed-gas separation factor of 3.0 at the highest feed R410A pressure tested. Overall, the newly fabricated IoNF-MMMs allowed the separation of the near-azeotropic R410A mixture to recover the low-GWP R32 gas, which is of great interest for the circular economy of the refrigeration sector.

Download Full-text

Free Volume and Gas Permeation in Anthracene Maleimide-Based Polymers of Intrinsic Microporosity

Membranes ◽

10.3390/membranes5020214 ◽

2015 ◽

Vol 5 (2) ◽

pp. 214-227 ◽

Cited By ~ 14

Author(s):

Muntazim Khan ◽

Volkan Filiz ◽

Thomas Emmler ◽

Volker Abetz ◽

Toenjes Koschine ◽

...

Keyword(s):

Free Volume ◽

Gas Permeation ◽

Polymers Of Intrinsic Microporosity ◽

Intrinsic Microporosity

Download Full-text

A Gas-Permeation Controllable Packaging Membrane with Porous Microspheres as Gas “Switches” for Efficient Preservation of Litchi

Journal of Agricultural and Food Chemistry ◽

10.1021/acs.jafc.1c02293 ◽

2021 ◽

Author(s):

Jinju Ma ◽

Zhiqiang Zhou ◽

Kai Li ◽

Xinghao Tu ◽

Kun Li ◽

...

Keyword(s):

Gas Permeation ◽

Porous Microspheres

Download Full-text

Design and Gas Separation Performance of Imidazolium Poly(ILs) Containing Multivalent Imidazolium Fillers and Crosslinking Agents

Polymers ◽

10.3390/polym13091388 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1388

Author(s):

Kathryn E. O’Harra ◽

Emily M. DeVriese ◽

Erika M. Turflinger ◽

Danielle M. Noll ◽

Jason E. Bara

Keyword(s):

Small Molecules ◽

Crosslinking Agent ◽

Gas Permeation ◽

Polymeric Matrix ◽

Separation Performance ◽

Ionic Polymers ◽

Co2 Solubility ◽

Imidazolium Cations ◽

Crosslinking Agents ◽

Gas Separation Performance

This work introduces a series of vinyl-imidazolium-based polyelectrolyte composites, which were structurally modified via impregnation with multivalent imidazolium-benzene ionic liquids (ILs) or crosslinked with novel cationic crosslinkers which possess internal imidazolium cations and vinylimidazolium cations at the periphery. A set of eight [C4vim][Tf2N]-based membranes were prepared via UV-initiated free radical polymerization, including four composites containing di-, tri-, tetra-, and hexa-imidazolium benzene ILs and four crosslinked derivatives which utilized tri- and tetra- vinylimidazolium benzene crosslinking agents. Structural and functional characterizations were performed, and pure gas permeation data were collected to better understand the effects of “free” ILs dispersed in the polymeric matrix versus integrated ionic crosslinks on the transport behaviors of these thin films. These imidazolium PIL:IL composites exhibited moderately high CO2 permeabilities (~20–40 Barrer), a 4–7× increase relative to corresponding neat PIL, with excellent selectivities against N2 or CH4. The addition of imidazolium-benzene fillers with increased imidazolium content were shown to correspondingly enhance CO2 solubility (di- < tri- < tetra- < hexa-), with the [C4vim][Tf2N]: [Hexa(Im+)Benz ][Tf2N] composite showing the highest CO2 permeability (PCO2 = 38.4 Barrer), while maintaining modest selectivities (αCO2/CH4 = 20.2, αCO2/N2 = 23.6). Additionally, these metrics were similarly improved with the integration of more ionic content bonded to the polymeric matrix; increased PCO2 with increased wt% of the tri- and tetra-vinylimidazolium benzene crosslinking agent was observed. This study demonstrates the intriguing interactions and effects of ionic additives or crosslinkers within a PIL matrix, revealing the potential for the tuning of the properties and transport behaviors of ionic polymers using ionic liquid-inspired small molecules.

Download Full-text

Optical, thermal and gas separation properties of acetate-containing copoly(ether-imide)s based on 6FDA and fluorenyl diamines

High Performance Polymers ◽

10.1177/0954008318822118 ◽

2019 ◽

Vol 31 (9-10) ◽

pp. 1101-1111 ◽

Cited By ~ 2

Author(s):

Yunhua Lu ◽

Jican Hao ◽

Guoyong Xiao ◽

Lin Li ◽

Zhizhi Hu ◽

...

Keyword(s):

Gas Separation ◽

Gas Permeation ◽

Light Transmittance ◽

Step Method ◽

Ether Linkage ◽

Nuclear Magnetic Resonance Spectrometer ◽

Thermogravimetric Analyzer ◽

Structures And Properties ◽

Infrared Spectrometer ◽

The Ideal

The diamine, 9,9-bis[4-(4-amino-3-hydroxylphenoxy)phenyl]fluorene (BAHPPF) was synthesized by the modified two-step method. Then, a series of acetate-containing copoly(ether-imide)s were prepared by the copolymerization of BAHPPF, 9,9-bis(4-aminophenyl)fluorene (BAF) and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) followed by chemical imidization. The structures and properties of the BAHPPF and copoly(ether-imide)s were characterized by nuclear magnetic resonance spectrometer (NMR), Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), ultraviolet-visible spectrophotometer (UV-VIS), and tensile testing. Single gas permeation performances of these copoly(ether-imide)s were also studied for five representative gases of interest including H2, O2, N2, CO2, and CH4. The experimental results showed that the copoly(ether-imide)s showed excellent optical properties with high light transmittance above 80.2% at 450 nm. The glass transition temperature of these copolymers were higher than 333°C. Their tensile strength and Young’s module also increased, and the elongation decreased with the decrease of BAHPPF. High gas permeabilities of copoly(ether-imide)s were obtained, and the ideal selectivity of CO2/CH4 was improved due to the introduction of acetate group and flexible ether linkage. These copoly(ether-imide)s could be applied to the field of optics and gas separation.

Download Full-text