Polyimide asymmetric membranes: Elaboration, morphology, and gas permeation performance

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.

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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.

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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.

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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.

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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.

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