scholarly journals Hollow Fiber Polyimide Membranes Prepared in a Triple Orifice Spinneret: Effect of a Reduced Water Activity in the Bore Fluid on the Gas Separation Performance

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2211
Author(s):  
Paola Bernardo ◽  
Franco Tasselli ◽  
Gabriele Clarizia
Keyword(s):  
Gas Separation ◽  
Water Activity ◽  
Physical Aging ◽  
Saline Water ◽  
Water Solution ◽  
Gas Permeation ◽  
Hollow Fibers ◽  
Separation Performance ◽  
Fluid Composition ◽  
Gas Selectivity

Polyimide-based hollow fibers were spun using a triple orifice spinneret in order to apply them in gas separation. The membrane structure was tailored producing a porous external layer and a thin internal skin layer, that controlled the gas transport. The measurement of gas permeation rates and the morphological analysis were combined to obtain information on the performance of the membranes. The aim was to tune the inner top layer and investigate the role of the bore fluid on the gas permeation properties of the membranes. The bore fluid composition was explored by using water mixtures containing the solvent used for preparing the dope solution or a salt in order to reduce the water activity in the inner coagulant, but also a low amount of a crosslinker for improving the gas selectivity. The change of the dope flow-rate was also analyzed. At moderate dope flow-rates, the use of a saline water solution as bore fluid is more effective in enhancing the membrane gas selectivity with respect to a bore fluid containing certain amounts of solvent. This option represents a green approach for the preparation of the membrane. The behavior of the prepared hollow fibers over time (physical aging) in gas permeation was discussed.

scholarly journals Pentiptycene-based ladder polymers with configurational free volume for enhanced gas separation performance and physical aging resistance

2021 ◽  
Vol 118 (37) ◽  
pp. e2022204118
Author(s):  
Tanner J. Corrado ◽  
Zihan Huang ◽  
Dezhao Huang ◽  
Noah Wamble ◽  
Tengfei Luo ◽  
...  
Keyword(s):  
Free Volume ◽  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeation ◽  
Separation Performance ◽  
Structure Property ◽  
Mixed Gas ◽  
Initial Separation ◽  
Primary Advantage ◽  
Polymers Of Intrinsic Microporosity

Polymers of intrinsic microporosity (PIMs) have shown promise in pushing the limits of gas separation membranes, recently redefining upper bounds for a variety of gas pair separations. However, many of these membranes still suffer from reductions in permeability over time, removing the primary advantage of this class of polymer. In this work, a series of pentiptycene-based PIMs incorporated into copolymers with PIM-1 are examined to identify fundamental structure–property relationships between the configuration of the pentiptycene backbone and its accompanying linear or branched substituent group. The incorporation of pentiptycene provides a route to instill a more permanent, configuration-based free volume, resistant to physical aging via traditional collapse of conformation-based free volume. PPIM-ip-C and PPIM-np-S, copolymers with C- and S-shape backbones and branched isopropoxy and linear n-propoxy substituent groups, respectively, each exhibited initial separation performance enhancements relative to PIM-1. Additionally, aging-enhanced gas permeabilities were observed, a stark departure from the typical permeability losses pure PIM-1 experiences with aging. Mixed-gas separation data showed enhanced CO2/CH4 selectivity relative to the pure-gas permeation results, with only ∼20% decreases in selectivity when moving from a CO2 partial pressure of ∼2.4 to ∼7.1 atm (atmospheric pressure) when utilizing a mixed-gas CO2/CH4 feed stream. These results highlight the potential of pentiptycene’s intrinsic, configurational free volume for simultaneously delivering size-sieving above the 2008 upper bound, along with exceptional resistance to physical aging that often plagues high free volume PIMs.

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

Nanomaterials ◽  
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.

scholarly journals The CO2/CH4 Separation Potential of ZIF-8/Polysulfone Mixed Matrix Membranes at Elevated Particle Loading for Biogas Upgradation Process

2020 ◽  
Vol 10 (2) ◽  
pp. 213-219
Author(s):  
Putu Doddy Sutrisna ◽  
Ronaldo Pangestu Hadi ◽  
Jonathan Siswanto ◽  
Giovanni J Prabowo
Keyword(s):  
Renewable Energy ◽  
Gas Separation ◽  
Gas Permeability ◽  
Gas Permeation ◽  
Degree Of Crystallinity ◽  
Polymeric Membrane ◽  
Mixed Matrix Membranes ◽  
Separation Performance ◽  
Particle Loading ◽  
Inorganic Particles

Biogas is a renewable energy that has been explored widely in Indonesia to substitute non-renewable energy. However, the presence of certain gas, such as carbon dioxide (CO2), can decrease the calorific value and generate greenhouse gas. Hence, the separation of CO2 from methane (CH4) occurs as a crucial step to improve the utilization of biogas. The separation of CH4/CO2 can be conducted using a polymeric membrane that needs no chemical, hence considered as an environmentally friendly technique. However, the utilization of polymeric membrane in gas separation processes is hampered by the trade-off between gas throughput and selectivity. To solve this problem, the incorporation of inorganic particles, such as Zeolitic Imidazolate Framework-8 (ZIF-8) particles, into the polymer matrix to improve the gas separation performance of the membrane has been conducted recently. In this research, ZIF-8 has been incorporated into Polysulfone matrix to form ZIF-8/Polysulfone-based membrane by simple blending and phase inversion techniques in flat sheet configuration. The pure gas permeation tests showed an increase in gas permeability (26 Barrer compared to 17 Barrer) after the inclusion of ZIF-8 particles with a slight decrease in CO2/CH4selectivity for particle loading more than 15wt. %. Therefore, the membrane with 15wt. % of particles showed the best performance in terms of gas selectivity. This result was due to the aggregation of ZIF-8 particles at particle loading higher than 15wt. %. Chemical analysis indicated an interaction between filler and polymer, and there were increases in the degree of crystallinity after the incorporation of ZIF-8.

Preparation and performance characterization of novel PVA blended with fluorinated polyimide membrane for gas separation

2020 ◽  
pp. 095400832095970
Author(s):  
Yunwu Yu ◽  
Peng Lin ◽  
Ye Zhao ◽  
Changwei Liu ◽  
Changwei Xu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Gas Separation ◽  
Amic Acid ◽  
Gas Permeation ◽  
Separation Performance ◽  
Hydroxyl Groups ◽  
Operating Pressure ◽  
Polyimide Membrane ◽  
Fluorinated Polyimide

Fluorinated polyimide and PVA blending membranes were prepared by aqueous solution casting. We chose a poly (amic acid) ammonium salt (PAAS) in aqueous solution based on a novel green strategy as the PI precursor. The blending membranes were characterized by ATR-FTIR, DSC, TGA and gas permeation measurement. The ATR-FTIR analysis revealed that the imidization reaction of 6FPI based on aqueous precursor was completed at 180°C and hydrogen bonds formed between PVA and 6FPI. 6FPI showed good compatibility with PVA segment in blending membranes without obvious separated phase structure. The blending membranes showed high separation properties, for blending with 6FPI the gas separation performance stability was improved due to the hydrogen bonds between hydroxyl groups of PVA and carbonyl groups of 6FPI, and the rigid structure of 6FPI. At high operating pressure 10 bar, the CO2 permeability and CO2/N2 selectivity remained rather high. Using water as the solvent in the PAAS synthesis and membrane preparation is more environmentally friendly and less costly.

scholarly journals Recovery of free volume in PIM-1 membranes through alcohol vapor treatment

2021 ◽  
Author(s):  
Faiz Almansour ◽  
Monica Alberto ◽  
Rupesh S. Bhavsar ◽  
Xiaolei Fan ◽  
Peter M. Budd ◽  
...  
Keyword(s):  
Binary Mixture ◽  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeability ◽  
Separation Performance ◽  
Aging Effects ◽  
Methanol Vapor ◽  
Alcohol Vapor ◽  
Industrial Level ◽  
Vapor Treatment

AbstractPhysical aging is currently a major obstacle for the commercialization of PIM-1 membranes for gas separation applications. A well-known approach to reversing physical aging effects of PIM-1 membranes at laboratory scale is soaking them in lower alcohols, such as methanol and ethanol. However, this procedure does not seem applicable at industrial level, and other strategies must be investigated. In this work, a regeneration method with alcohol vapors (ethanol or methanol) was developed to recover permeability of aged PIM-1 membranes, in comparison with the conventional soaking-in-liquid approach. The gas permeability and separation performance, before and post the regeneration methods, were assessed using a binary mixture of CO2 and CH4 (1:1, v:v). Our results show that an 8-hour methanol vapor treatment was sufficient to recover the original gas permeability, reaching a CO2 permeability > 7000 barrer.

scholarly journals A Novel Composite Material UiO-66@HNT/Pebax Mixed Matrix Membranes for Enhanced CO2/N2 Separation

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 693
Author(s):  
Fei Guo ◽  
Bingzhang Li ◽  
Rui Ding ◽  
Dongsheng Li ◽  
Xiaobin Jiang ◽  
...  
Keyword(s):  
Composite Material ◽  
Gas Separation ◽  
Halloysite Nanotubes ◽  
Gas Permeation ◽  
Mixed Matrix Membranes ◽  
Mixed Matrix Membrane ◽  
Separation Performance ◽  
Mixed Matrix ◽  
Transport Pathways ◽  
Gas Separation Performance

Mixing a polymer matrix and nanofiller to prepare a mixed matrix membrane (MMM) is an effective method for enhancing gas separation performance. In this work, a unique UiO-66-decorated halloysite nanotubes composite material (UiO-66@HNT) was successfully synthesized via a solvothermal method and dispersed into the Pebax-1657 matrix to prepare MMMs for CO2/N2 separation. A remarkable characteristic of this MMM was that the HNT lumen provided the highway for CO2 diffusion due to the unique affinity of UiO-66 for CO2. Simultaneously, the close connection of the UiO-66 layer on the external surface of HNTs created relatively continuous pathways for gas permeation. A suite of microscopy, diffraction, and thermal techniques was used to characterize the morphology and structure of UiO-66@HNT and the membranes. As expected, the embedding UiO-66@HNT composite materials significantly improved the separation performances of the membranes. Impressively, the as-obtained membrane acquired a high CO2 permeability of 119.08 Barrer and CO2/N2 selectivity of 76.26. Additionally, the presence of UiO-66@HNT conferred good long-term stability and excellent interfacial compatibility on the MMMs. The results demonstrated that the composite filler with fast transport pathways designed in this study was an effective strategy to enhance gas separation performance of MMMs, verifying its application potential in the gas purification industry.

Investigation of the silica pore size effect on the performance of polysulfone (PSf) mixed matrix membranes (MMMs) for gas separation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gholamhossein Vatankhah ◽  
Babak Aminshahidy
Keyword(s):  
Mesoporous Silica ◽  
Pore Size ◽  
Gas Separation ◽  
Gas Permeation ◽  
Mixed Matrix Membranes ◽  
Separation Performance ◽  
Mixed Matrix ◽  
Small Pore ◽  
Mcm 41 ◽  
Matrix Membranes

Abstract MCM-41 and SBA-15 mesoporous silica materials with different pore sizes (3.08 nm for small pore size MCM-41 (P 1), 5.89 nm for medium pore size SBA-15 (P 2), and 7.81 nm for large pore size SBA-15 (P 3)) were synthesized by the hydrothermal method and then functionalized with 3-aminopropyltrietoxysilane by postsynthesis treatments. Next, polysulfone-mesoporous silica mixed matrix membranes (MMMs) were prepared by the solution casting method. The obtained materials and MMMs were characterized by various techniques including X-ray diffraction, scanning electron microscopy, and N2 adsorption-desorption, and Brunauer-Emmett-Teller method to examine the crystallinity, morphology, and particle size, pore volume, specific surface area, and pore size distribution, respectively. Finally, the gas permeation rates of prepared MMMs were measured in 8 bar and 25 °C and the effect of pore size of modified and unmodified mesoporous silica on the gas separation performance of these MMMs were investigated. The experimental results indicate that the carbon dioxide (CO2) and methane (CH4) permeability and CO2/CH4 selectivity were increased with an enhancement in the particle pore size.

scholarly journals Thermal Cross Linking of Novel Azide Modified Polymers of Intrinsic Microporosity—Effect of Distribution and the Gas Separation Performance

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1241 ◽  
Author(s):  
Silvio Neumann ◽  
Gisela Bengtson ◽  
David Meis ◽  
Volkan Filiz
Keyword(s):  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeability ◽  
Time Lag ◽  
Polymer Chains ◽  
Separation Performance ◽  
Polymer Backbone ◽  
Cross Linkage ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

The synthesis of polymers of intrinsic microporosity (PIM) modified with azide groups, the cross linkage by nitrene reaction and their performance as gas separation membranes are reported. The azide modification of the spirobisindane units in the polymer backbone was done by post functionalization of methylated spirobisindane containing polymers. These polymers differ in distribution and concentration of the azide group containing spirobisindane units by applying perfectly alternating and randomly distributed copolymers along the polymer chains. To investigate the influence of concentration of the azide groups, additionally the homopolymer of methylated spirobisindane was synthesized and subjected to identical treatments and characterizations as both copolymers. Cross linkage by nitrene reaction was examined by different temperature treatments at 150, 200, 250 and 300 °C. Characterization of the new polymers was performed by NMR, SEC and FT-IR. Furthermore, the crosslinking process was investigated by means of solid state NMR, TGA-FTIR, DSC and isoconversional kinetic analysis performed with TGA. Gas permeability of CO2, N2, CH4, H2 and O2 was determined by time lag experiments and ideal selectivities for several gas pairs were calculated. The two azide groups per repeating unit degrade during thermal treatments by release of nitrogen and form mechanically stable PIM networks, leading to an increase in gas permeability while selectivity remained nearly constant. Measured diffusivity and solubility coefficients revealed differences in the formation of free volume elements depending on distribution and concentration of the azide groups. Aging studies over about five months were performed and physical aging rates (βP) were evaluated with regard to the concentration and distribution of curable azide functionalities. Subsequently, the enhanced sieving effect during aging resulted in membrane materials that surpassed the Robeson upper bound in selected gas pairs.

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