Carbon Dioxide Permeability Research Articles

Fabrication of composite hollow fiber membranes with thin film selective layers from highly permeable polymers

Fabrication of highly efficient composite gas separation membranes involves selection and pretreatment of the support material. In the present work, porous support pretreatment was for the first time studied for deposition of thin selective layers made from highly permeable organosilicon polymers. Asymmetric polysulfone hollow fiber membranes with mesoporous skin layer structure were employed as supports. It was shown that preliminary impregnation of the support pores is essential for composite membranes fabrication. If poly[1-(trimethylsilyl)-1-propyne] layers from casting solution are deposited onto the polysulfone support without impregnation, the casting solution penetrates the mesoporous layer to a depth of > 1 μm, thus predominantly (> 90%) contributing the overall mass transfer resistance, as estimated by the resistance-in-series model. Such membranes provide relatively poor transport properties: carbon dioxide permeance is 0.2-0.3 m3/(m2·h·bar). Preliminary impregnation of porous support by distilled water or aqueous glycerol solution prevents casting solution penetration into porous support and results in defect-free thin polymer layer. According to SEM, the deposited selective layer thickness is less than 1 μm. Composite membranes fabricated via this technique provide permeance increase more than order of magnitude. The composite membranes with poly[1-(trimethylsilyl)-1-propyne] and polydimethylsiloxane selective layers show high transport properties in gas-liquid membrane contactors.

Central Corneal Edema with Scleral-Lens Wear

ABSTRACTPurpose: To evaluate the safety of scleral-lens designs, we model and clinically assess central corneal edema induced by scleral-lens wear for healthy subjects.Materials and Methods: Central corneal swelling during scleral-lens wear is measured using optical coherence tomography (OCT). Transport resistances are modeled for oxygen diffusion through the scleral lens and post-lens tear-film (PoLTF), and into the cornea. Oxygen deficiency in the cornea activates anaerobic metabolic reactions that induce corneal edema. Oxygen permeability, carbon-dioxide permeability, settled-lens PoLTF thickness, and scleral-lens thickness are varied in the calculations to mimic different lens fits.Results: Transport modeling predicts that for open eyes, increasing PoLTF thickness from 50 to 400 µm increases central corneal swelling by approximately 1–1.5% when oxygen transmissibility (Dk/L) is greater than 10 hBarrer/cm (i.e., hectoBarrer/cm). Although swelling is larger for oxygen Dk/L < 10 hBarrer/cm, PoLTF thickness has minimal impact in this range. For open eye, oxygen transmissibility of the lens plays a significant role in corneal edema, but is negligible when oxygen Dk/L is > 40 hBarrer/cm. For closed eye, central corneal swelling is greater than 5% for an oxygen Dk/L range of 0–100 hBarrer/cm with typical lens-fitting parameters. For carbon-dioxide transmissibilities increasing from 50 to 250 hBarrer/cm and with a fixed oxygen Dk/L of 25 hBarrer/cm, calculated swelling diminishes by an additional 0.5%. Comparison of model calculations to clinical-swelling data is within the error range of the clinical measurements.Conclusions: Oxygen/metabolite transport calculations for open-eye scleral-lens wear show that typical PoLTF thicknesses fitted by clinicians (i.e., PoLTF thicknesses < 400 µm) with modern scleral lenses (i.e., oxygen Dk/L > 25 hBarrer/cm) produce corneal swelling of less than 2% in agreement with experiment. Therefore, scleral lenses prescribed today evoke less than physiological hypoxic swelling (i.e., less than 4%) for healthy corneas during open-eye. Closed-eye wear, however, appears clinically unsafe.

Cholesterol is the main regulator of the carbon dioxide permeability of biological membranes.

We present here a compilation of membrane CO2 permeabilities (Pco2) for various cell types from the literature. Pco2 values vary over more than two orders of magnitude. Relating Pco2 to the cholesterol content of the membranes shows that, with the exception of red blood cells, it is essentially membrane cholesterol that determines the value of Pco2. Thus, the observed strong modulation of Pco2 in the majority of membranes is caused by cholesterol rather than gas channels.

PBAT/organoclay composite films—part 2: effect of UV aging on permeability, mechanical properties and biodegradation

Biodegradable alternatives are required in order to minimize the environmental impacts caused by inadequate disposal of plastics, especially fast-discharge plastics such as those used in the packaging. This work studied the permeability, mechanical properties and biodegradability of PBAT/organoclay composite films. The materials were melt-mixed in an internal laboratory mixer, and films containing 1, 3 and 5% of organoclay were prepared in a chill roll extruder. The samples were subjected to UV radiation, and their properties were evaluated before and after accelerated aging. Results show that tensile properties, gas permeability and biodegradation depend on filler content and that oxygen and carbon dioxide permeabilities were affected by UV aging. Although the mechanical properties are negatively affected by filler incorporation, oxygen and carbon dioxide permeabilities decreased and biodegradability increased in the composites, making them an interesting option for use in packaging.

Effect of glucose fouling on the dissolved gases permeation through maximum‐crystallized poly(lactic acid) films

ABSTRACTIn this study, we investigated the effect of fouling on the dissolved oxygen and carbon dioxide permeation in water through maximum‐crystallized poly(lactic acid) (PLA) films by using proton nuclear magnetic resonance, attenuated total reflection‐Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, and ultraviolet–visible spectroscopy, contact angle, water content ratio, and dissolved gas permeation. Fouling means the adhesion of contents on a container's internal surface, where content adhesion can directly influence the barrier property of the container. Glucose, a beverage ingredient, was used as a foulant. The permeation of dissolved gases in amorphous PLA film, maximum‐crystallized PLA film, and fouled maximum‐crystallized PLA film was determined. The decreased interstices in the polymer chains during crystallization resulted in the inhibition of the diffusion and decrease in the permeability coefficient of the gases. Moreover, the slope of the permeability coefficient for carbon dioxide in the Arrhenius plot was found smaller than that of oxygen's. This result indicated that the gas barrier property of dissolved carbon dioxide was considerably influenced by solubility and readily decreases during glucose fouling. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46604.

Optimization of the gas separation performance of polyurethane–zeolite 3A and ZSM-5 mixed matrix membranes using response surface methodology

Optimization of the gas separation performance of polyurethane–zeolite 3A and ZSM-5 mixed matrix membranes using response surface methodology

Application of acrylic-based coatings for concrete protection

The paper presents a description of acrylic-based polymers used in civil engineering for concrete protection. Some information on chemistry and properties of the acrylic coatings is included together with current trends in coating technology. Moreover, the paper shows test results, that is barrier properties and SEM observations of a commercial elastic acrylic-based polymer subject to artificial weathering for 1000h. The studies showed that the weathering did not change carbon dioxide permeability of the tested coating and its influence on water vapour permeability of the material was also very small. The test results show that an assessment of coating performance based only on barrier properties is not enough.

An Investigation of the Barrier Properties and of the Residual Acetaldehyde in Polyethylene Terephthalate Composites

The diffusion cell to a Tsvet-800 chromatograph for determining the gas permeability of polymeric materials has been optimised. The oxygen permeability and the carbon dioxide permeability of polymer composites based on polyethylene terephthalate and polybutylene terephthalate have been studied. The optimum compositions, combining high barrier properties and a low acetaldehyde content, have been found.

Effect of High Pressure Carbon Dioxide Exposure on the Permeation Properties of Asymmetric Polysulfone Membranes for Gas Separation

In this study, the dependence of permeability on the feed pressure for glassy asymmetric polysulfone membranes has been investigated. Pure CO2 and CH4 were used as test gases. In pure gas experiments with CO2, the untreated membrane showed that the carbon dioxide permeation rate increased with increasing feed pressure from one bar onwards. This is because carbon dioxide behaves as a plasticizing agent by expanding the polymer lattice and increased the frequency of molecular motions of the polymer. Moreover, high carbon dioxide concentration in the polymer film disrupts the chain packing, thereby leading to a larger free volume and enhanced rates of segmental motions. Due to swelling of the polymer matrix, the structure of the polymer matrix is loosened and consequently polymer chains become more flexible. For the treated membrane, the permeability of carbon dioxide does not increase with feed pressure but gives a steady state value over the feed pressure ranges investigated. This was in agreement with scanning electron microscopy studies, which revealed that heat treatment densified the membrane skin layer. Thus, a subsequent heat treatment to the membrane is necessary in suppressing the plasticization effect.

Preparation and characterization of a chitosan film with grape seed extract-carvacrol microcapsules and its effect on the shelf-life of refrigerated Salmon (Salmo salar)

Preparation and characterization of a chitosan film with grape seed extract-carvacrol microcapsules and its effect on the shelf-life of refrigerated Salmon (Salmo salar)

Selective-exhaust gas recirculation for CO2 capture using membrane technology

Selective-exhaust gas recirculation for CO2 capture using membrane technology

Effect of calcium carbonate nanoparticles on barrier properties and biodegradability of polylactic acid

In this study, the effect of calcium carbonate (CaCO3) nanoparticles on the barrier properties and biodegradability of polylactic acid (PLA) was investigated. For this purpose, nanocomposite films with various CaCO3 nanoparticle contents (0, 3, 5, 10, and 15 wt%) were prepared by solution casting method. The gas permeability of nitrogen (N2), oxygen (O2), and carbon dioxide (CO2) was evaluated through a constant volume and variable pressure apparatus at different pressures and temperatures. According to results, barrier properties were improved by loading CaCO3 nanoparticles up to 5 wt%, and the gas permeability of CO2, O2, and N2 was decreased from 1.4, 0.31, and 0.07 Barrer to 0.48, 0.095, and 0.019 Barrer, respectively. In addition, it was also observed that the gas permeability of samples was decreased by increasing feeding pressure and increased by enhancing temperature. Furthermore, morphological results confirmed the formation of agglomerations and large clusters over 5 wt% CaCO3 nanoparticles. Finally, the thermal properties and biodegradability of PLA were increased by employing CaCO3 nanoparticles. These results suggested PLA nanocomposites as favorable candidates for food packaging applications.

Solvent‐Templated Block Ionomers for Base‐ and Acid‐Gas Separations: Effect of Humidity on Ammonia and Carbon Dioxide Permeation

Abstract As energy needs continue to drive the development of biogas and fossil‐fuel technologies, methods by which to selectively remove basic (NH3) and acidic (CO2) gases are becoming increasingly important, especially in light of global climate change. Block copolymers are considered as suitable membrane candidates in gas separations due to the ability of such copolymers to microphase‐separate and spontaneously form nanoscale morphologies that exhibit spatially modulated chemical specificity. Incorporation of charged moieties along the midblock of a thermoplastic elastomeric multiblock copolymer yields an amphiphilic block ionomer possessing a flexible molecular network stabilized by rigid endblocks. The presence of hydrophilic microdomains introduces an important consideration regulating molecular transport: humidity. In this study, solvent‐templating paradigms are employed to control the morphologies of midblock‐sulfonated pentablock ionomers, as discerned by electron microscopy and X‐ray scattering. The effect of humidity on the permeation of NH3, CO2, and N2is then investigated through the resulting membranes. As expected, NH3permeates significantly faster than N2, especially under humid conditions. Although not as pronounced, similar behavior is observed for CO2, thereby establishing that this block ionomer is generally selective to humidified polar gases.

The Gas Permeability of Polyolefin Blends Containing a Glass Flake Filler

The results of investigating the influence of the concentration of glass flake filler on oxygen, carbon dioxide, and water vapour permeability in composites based on high-density polyethylene blends are given.

Mechanical and Gas Barrier Properties of Poly(L-Lactic Acid) by Plasma-Enhanced Chemical Vapor Deposition of SiOx

ABSTRACTIn this work, poly(L-lactic acid) film was coated with SiOx by the plasma-enhanced chemical vapor deposition with different deposition times. Compared with the neat poly(L-lactic acid) film, the oxygen (O2), carbon dioxide (CO2), nitrogen (N2), and water vapor permeability of the poly(L-lactic acid)/SiOx60 film (depositing for 60 min) decreased by 40.7, 30.6, 58.7, and 53.4% at 25°C, respectively. After treated by the SiOx deposition, the gas permselectivity of the poly(L-lactic acid)/SiOx60 film, such as α(CO2/O2), α(O2/N2), and α(CO2/N2), increased by 17.2, 43.9, and 67.5% at 25°C, respectively. In addition, Young’s modulus and tensile strength of poly(L-lactic acid)/SiOx60 film increased by 107.2 and 49.3%, respectively. Moreover, the poly(L-lactic acid)/SiOx60 films still kept good toughness with an elongation at break of 50.7%.

Hydrothermal stability of silica, hybrid silica and Zr-doped hybrid silica membranes

Hydrothermal stability of silica, hybrid silica and Zr-doped hybrid silica membranes

Zeolite A‐polypropylene and silver‐zeolite A‐polypropylene composite films for antibacterial and breathable applications

ABSTRACTPolypropylene (PP) composite films were successfully prepared using melt blending by directly mixing PP pellets with zeolite A or silver‐zeolite A powder and then blowing. All the prepared films were characterized in terms of their physical, mechanical, optical, and gas permeability properties. The structure of each composite film was similar to that of the pure PP film. The crystallinity and glossy quality of the composite films were increased by the addition of silver, zeolite, and maleic anhydride grafted PP (PP‐g‐MA). The composite PP film with zeolite A and PP‐g‐MA exhibited a level of oxygen and carbon dioxide permeation (6438 and 15,087 cc m−2 day−1 atm−1, respectively). Finally, all the films were evaluated for their antibacterial activity and fruit packaging applications. Silver‐zeolite A‐PP composite films exhibited a bactericidal activity of 79% against Staphylococcus aureus and 52% against Escherichia coli, while the zeolite A‐PP film could extend the shelf‐life of bananas for over a week. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45450.

Carbon dioxide permeation through ceramic-carbonate dual-phase membrane-effects of sulfur dioxide

Carbon dioxide permeation through ceramic-carbonate dual-phase membrane-effects of sulfur dioxide

Sulfonated polyimide/ionic liquid composite membranes for carbon dioxide separation

A series of composite membranes (SPI-NTf2 and SPI-PF6) consisting of a sulfonated polyimide (SPI) and an ionic liquid (IL), either [C4mim][NTf2] or [C4mim]PF6, where [C4mim] and [NTf2] stand for 1-butyl-3-methylimidazolium and bis(trifluoromethanesulfonyl)amide, respectively, were prepared, and their thermal, mechanical and gas (carbon dioxide (CO2) and N2) permeation properties were systematically investigated. The ILs functioned as plasticizers of the SPI, making the composite membranes softer (lower Young’s modulus and larger elongation at break). However, SPI-NTf2 (75), containing 75 wt% [C4mim][NTf2], still exhibited a Young’s modulus higher than 10 MPa, which is much higher than that reported for common IL/polymer composites. The SPI membrane behaved as a gas barrier membrane; however, the addition of IL greatly enhanced gas permeability. Consequently, SPI-NTf2 (75) exhibited CO2 permeability ( ) of 412 Barrer at 30 °C and selectivity against N2 ( ) of 27. The SPI-PF6 composite membranes showed similar behavior; however, gas permeability exhibited by these membranes was lower than that exhibited by the SPI-NTf2 composite membranes. In permeation tests under mixed-gas conditions, the value decreased than that under single-gas conditions, whereas increased, and decreased (from the range 29−27 to 12–16). Ionic liquid (IL)/sulfonated polyimide (SPI) composite membranes exhibit high carbon dioxide (CO2) permeability with good CO2/N2 selectivity. CO2 permeation coefficients (PCO2) are higher than 400 Barrer at 30 °C when the composite membranes include 75 wt% of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide. The IL/SPI composite membranes also exhibits excellent mechanical properties (Young’s modulus ⩾10 MPa) and can be processed into thin and uniform membranes. These characteristics are preferable as CO2 separation membranes.

Carbon dioxide permeability of building materials and their impact on bedroom ventilation need

Carbon dioxide permeability of building materials and their impact on bedroom ventilation need