Gas permeability and free volume in poly(amide-b-ethylene oxide)/polyethylene glycol blend membranes

Polymeric composite membranes in carbon dioxide capture process: a review

Carbon dioxide (CO₂) emission to the atmosphere is the prime cause of certain environmental issues like global warming and climate change, in the present day scenario. Capturing CO₂ from various stationary industrial emission sources is one of the initial steps to control the aforementioned problems. For this concern, a variety of resources, such as liquid absorbents, solid adsorbents, and membranes, have been utilized for CO₂ capturing from various emission sources. Focused on membrane-based CO₂ capture, polymeric membranes with composite structure (polymeric composite membrane) offer a better performance in CO₂ capturing process than other membranes, due to the composite structure it offers higher gas flux and less material usage, thus facile to use high performed expensive material for membrane fabrication and achieved good efficacy in CO₂ capture. This compressive review delivers the utilization of different polymeric composite membranes in CO₂ capturing applications. Further, the types of polymeric materials used and the different physicochemical modifications of those membrane materials and their CO₂ capturing ability are briefly discussed in the text. In conclusion, the current status and possible perspective ways to improve the CO₂ capture process in industrial CO₂ gas separation applications are described in this review.

CO2-selective poly (ether-block-amide)/polyethylene glycol composite blend membrane for CO2 separation from gas mixtures

This work focuses on the preparation of composite blend membranes based on poly (ether-block-amide) (Pebax-1657) by incorporating polyethylene glycol (PEG) for gas separation applications. The influence of PEG with different molecular weights (PEG600, PEG1500, and PEG4000) at loading content in the range of 10%wt. to 40%wt. was investigated on the microstructure and gas separation performance of the prepared blend membranes. The fabricated membranes were characterized using SEM, XRD, and water contact angle analyses. Based on the experimental results, the blending of low molecular weight PEG (PEG600) into the Pebax-1657 matrix increased the chain mobility of the membrane, led to a smooth microstructure, and improved the hydrophilicity of the blend membranes, as well as enhanced the gas permeability of N₂, O₂, CH₄, and CO₂, but only slightly affected the ideal selectivity of O₂/N₂, CH₄/N₂, CO₂/N₂, and CO₂/CH₄. In contrast, the incorporation of PEG1500 and PEG4000 meaningfully increased the membrane crystallinity, decreased chain mobility, resulted in a rough microstructure, and reduced the blend membranes' hydrophilicity. For CO₂/N₂ mixture, the Pebax/40%PEG600 membrane had CO₂ permeability of 62.9 Barrer and selectivity of 83.8, while the Pebax/20%PEG600 showed the CO₂ permeability of 63.12 Barrer and selectivity of 23.6 for CO₂/CH₄ separation.

Recent Progresses in Application of Membrane Bioreactors in Production of Biohydrogen

Biohydrogen is a clean and viable energy carrier generated through various green and renewable energy sources such as biomass. This review focused on the application of membrane bioreactors (MBRs), emphasizing the combination of these devices with biological processes, for bio-derived hydrogen production. Direct biophotolysis, indirect biophotolysis, photo-fermentation, dark fermentation, and conventional techniques are discussed as the common methods of biohydrogen production. The anaerobic process membrane bioreactors (AnMBRs) technology is presented and discussed as a preferable choice for producing biohydrogen due to its low cost and the ability of overcoming problems posed by carbon emissions. General features of AnMBRs and operational parameters are comprehensively overviewed. Although MBRs are being used as a well-established and mature technology with many full-scale plants around the world, membrane fouling still remains a serious obstacle and a future challenge. Therefore, this review highlights the main benefits and drawbacks of MBRs application, also discussing the comparison between organic and inorganic membranes utilization to determine which may constitute the best solution for providing pure hydrogen. Nevertheless, research is still needed to overcome remaining barriers to practical applications such as low yields and production rates, and to identify biohydrogen as one of the most appealing renewable energies in the future.

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

Blend membranes based on polyurethane and polyethylene glycol: exploring the impact of molecular weight and concentration of the second phase on gas permeation enhancement

This work seeks to explore the permeability dependence of polyurethane (PU)/polyethylene glycol (PEG) blend membranes on the molecular weight and composition of PEG constituent polymer. In this regard, gases with different polar nature were mixed (CO2/N2, CO2/CH4, and O2/N2) and subjected to a series of PU/PEG blends prepared via solution casting method. With the alteration of the molecular weight (1000, 2000, and 6000 g/mol) and composition (0, 10, 15, and 20 wt.%) of PEG in the blend films, the potentials of membranes in controlling the permeation of gas molecules within the films were quantified, compared, and discussed. It is known that the introduction of PEG into PU-based membranes causes the films to become more flexible, which brings advantages from an application point of view. Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and scanning electron microscopy analyses were used to study the microstructural changes in the prepared PU/PEG blend membranes. The selectivity of the films was obviously displaced by the introduction of PEG, particularly when higher-molecular-weight PEGs were used and the resulting hybrid membranes were subjected to a mixture of CO2/CH4 or CO2/N2 gases.

Constructing Ionic Liquid-Filled Proton Transfer Channels within Nanocomposite Membrane by Using Functionalized Graphene Oxide

Herein, nanocomposite membranes are fabricated based on functionalized graphene oxides (FGOs) and sulfonated poly(ether ether ketone) (SPEEK), followed by being impregnated with imidazole-type ionic liquid (IL). The functional groups (acidic group or basic group) on FGOs generate strong interfacial interactions with SPEEK chains and then adjust their motion and stacking. As a result, the nanocomposite membranes possess tunable interfacial domains as determined by its free volume characteristic, which provides regulated location for IL storage. The stored ILs act as hopping sites for water-free proton conduction along the FGO-constructed interfacial channels. The microstructure at SPEEK-FGO interface governs the IL uptake and distribution in nanocomposite membrane. Different from GO and vinyl imidazole functionalized GO (VGO), the presence of acidic (-SO3H) groups confers the p-styrenesulfonic acid functionalized GO (SGO) incorporated nanocomposite membrane loose interface and strong electrostatic attraction with imidazole-type IL, imparting an enhanced IL uptake and anhydrous proton conductivity. Nanocomposite membrane containing 7.5% SGO attains the maximum IL uptake of 73.7% and hence the anhydrous conductivity of 21.9 mS cm(-1) at 150 °C, more than 30 times that of SPEEK control membrane (0.69 mS cm(-1)). In addition, SGOs generate electrostatic attractions to the ILs confined within SGO-SPEEK interface, affording the nanocomposite membrane enhanced IL retention ability.

Effect of the reactive amino and glycidyl ether terminated polyethylene oxide additives on the gas transport properties of Pebax® bulk and thin film composite membranes

New CO₂ selective blend materials were tested for gas transport properties as thick film and thin film composite membrane.

Improving CO2/N2separation performance using nonionic surfactant Tween containing polymeric gel membranes

Schematic representation of the microstructure of PEBA2533 and PEBA2533/Tween gel membranes. Domain identification: A = crystalline hard PA blocks, B = soft PTMO and amorphous hard PA blocks, C = dissolved Tween.

Rational molecular design of PEOlated ladder-structured polysilsesquioxane membranes for high performance CO2 removal

By selectively introducing PEO groups into the ladder-structured polysilsesquioxane, PEO crystallization was suppressed, allowing for the exceptional CO₂ separation performance.

Porous ceramic hollow fiber-supported Pebax/PEGDME composite membrane for CO2 separation from biohythane

Ceramic hollow fiber-supported Pebax/PEGDME membrane was prepared to separate CO₂. The composite membrane showed excellent performance of removing CO₂ from biohythane. The ideal CO₂/H₂ selectivity increased to 26 when temperature decreased to 10 °C.

Effect of hollow silica spheres on water vapor permeability of polyacrylate film

Hollow silica spheres with different hollow size and shell thickness were synthesized via a template method using PS spheres as templates and characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Brunauer–Emmett–Teller analysis.

Development of nanocomposite membranes containing modified Si nanoparticles in PEBAX-2533 as a block copolymer and 6FDA-durene diamine as a glassy polymer

Nanocomposite membranes of modified Si nanoparticles as inorganic filler in two different polymers from two different categories were developed. Synthesized 6FDA-durene diamine as a glassy polymer and PEBAX-2533 as a block copolymer were used as the polymer matrix to develop the nanocomposite membranes of modified Si nanoparticles in polymer matrix. The scanning transmission electron microscopy (STEM) results showed nice nano size dispersion of inorganic nanofillers in the polymer matrix in both cases. Pure gas permeation for the gases CO2, CH4, N2, and O2 and mixed gas of CO2-N2 was carried out at 2 and 6 bar for single gas and 2.6 bar for mixed gas using the developed nanocomposite membranes. The loading of inorganic fillers in the PEBAX-2533 polymer matrix resulted in a dramatic increase in gas permeability for all tested gases, while a decrease was observed for CO2/N2 and CO2/CH4 selectivities with small amounts of loading of filler. With higher loading of inorganic filler, the selectivity did not change, which is probably due to the formation of nanogap around the nanoparticles in the polymer matrix. The dispersion of the nanoparticle inorganic fillers in 6FDA-durene polymer matrix caused an increase on the fractional free volume of the polymer matrix due to the disruption of the polymer chain in the presence of the inorganic fillers. Hence, this disruption resulted in an increase of gas permeability for both single and mixed gases, also with an increase in CO2/N2 and CO2/CH4 selectivities.