Membranes

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12 pages, 2515 KiB

Open AccessArticle

Recovery of Methanol during Natural Gas Dehydration Using Polymeric Membranes: Modeling of the Process

by Daria Miroshnichenko, Vladimir Teplyakov and Maxim Shalygin

Membranes 2022, 12(12), 1176; https://doi.org/10.3390/membranes12121176 - 22 Nov 2022

Cited by 2 | Viewed by 1732

Abstract

A significant proportion of natural gas (NG) is produced in cold climates, where conditions are relevant to the formation of gas hydrates in raw gas stream. Methanol is often used as an effective inhibitor of hydrate formation. Further conditioning of NG includes dehydration, [...] Read more.

A significant proportion of natural gas (NG) is produced in cold climates, where conditions are relevant to the formation of gas hydrates in raw gas stream. Methanol is often used as an effective inhibitor of hydrate formation. Further conditioning of NG includes dehydration, and the most common process of water vapor removal from NG is absorption. Absorption also provides removal of methanol vapors, which allows it reuse. The membrane method of natural gas dehydration is considered as a promising alternative; however, the study of methanol recovery by the membrane method, simultaneously to the dehydration of NG, has not been carried out previously. In addition, data on methanol vapor transfer in gas separation polymer membranes are almost absent in the literature. This paper evaluates the permeability coefficients of methanol vapors for several polymer materials, which are applied to the production of industrial membranes (PPO, PSf, CA). Mathematical modeling of the membrane process of NG dehydration with simultaneous recovery of methanol was performed. The dependencies of membrane area, methanol recovery and energy consumption for methane recycling and recompression on the process parameters are calculated. Obtained data show that the recovery of methanol during membrane dehydration of NG varies in the range 57–95%. The lowest values of membrane area and specific energy consumption were found for PPO based membrane. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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14 pages, 5687 KiB

Open AccessArticle

The Influence of Mechanical Stress Micro Fields around Pores on the Strength of Elongated Etched Membrane

by Venera Gumirova, Irina Razumovskaya, Pavel Apel, Sergey Bedin and Andrey Naumov

Membranes 2022, 12(11), 1168; https://doi.org/10.3390/membranes12111168 - 21 Nov 2022

Cited by 3 | Viewed by 1257

Abstract

The investigation of the mechanical properties of polymer track-etched membranes (TMs) has attracted significant attention in connection with the extended region of their possible applications. In the present work, the mechanical stress fields around the pores of an elongated polyethylene terephthalate TM and [...] Read more.

The investigation of the mechanical properties of polymer track-etched membranes (TMs) has attracted significant attention in connection with the extended region of their possible applications. In the present work, the mechanical stress fields around the pores of an elongated polyethylene terephthalate TM and around the 0.3 mm holes in model polymer specimens were studied in polarized light and with the finite element method. A break-up experiment showed the controlling role of stress field interaction in the forming of a microcrack system and the generation of a main crack with rupture of the TM (or model pattern). This interaction depended on the relative distance between the pores (holes) and their orientation. The results of the calculations of the pore distribution function over the surface of the TM via the net method and wavelet analysis are presented. The fractal character of pore distribution was established. The geometric characteristics of the TM pore system as initial defects are inherited by obtaining TM-based composites. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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9 pages, 1433 KiB

Open AccessArticle

A Novel Membrane-like 2D A’-MoS₂ as Anode for Lithium- and Sodium-Ion Batteries

by Ekaterina V. Sukhanova, Liudmila A. Bereznikova, Anton M. Manakhov, Hassan S. Al Qahtani and Zakhar I. Popov

Membranes 2022, 12(11), 1156; https://doi.org/10.3390/membranes12111156 - 16 Nov 2022

Cited by 5 | Viewed by 1921

Abstract

Currently, new nanomaterials for high-capacity lithium-ion batteries (LIBs) and sodium- ion batteries (SIBs) are urgently needed. Materials combining porous structure (such as representatives of metal–organic frameworks) and the ability to operate both with lithium and sodium (such as transition-metal dichalcogenides) are of particular [...] Read more.

Currently, new nanomaterials for high-capacity lithium-ion batteries (LIBs) and sodium- ion batteries (SIBs) are urgently needed. Materials combining porous structure (such as representatives of metal–organic frameworks) and the ability to operate both with lithium and sodium (such as transition-metal dichalcogenides) are of particular interest. Our work reports the computational modelling of a new A’-MoS₂ structure and its application in LIBs and SIBs. The A’-MoS₂ monolayer was dynamically stable and exhibited semiconducting properties with an indirect band gap of 0.74 eV. A large surface area, together with the presence of pores resulted in a high capacity of the A’-MoS₂ equal to ~391 mAg⁻¹ at maximum filling for both Li and Na atoms. High adsorption energies and small values of diffusion barriers indicate that the A’-MoS₂ is promising in the application of anode material in LIBs and SIBs. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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29 pages, 7175 KiB

Open AccessArticle

Profiled Ion-Exchange Membranes for Reverse and Conventional Electrodialysis

by Sergey Loza, Natalia Loza, Natalia Kutenko and Nikita Smyshlyaev

Membranes 2022, 12(10), 985; https://doi.org/10.3390/membranes12100985 - 11 Oct 2022

Cited by 10 | Viewed by 1540

Abstract

Profiled ion-exchange membranes are promising for improving the parameters of reverse electrodialysis due to the reduction of pumping power and electrical resistance. The smooth commercial heterogeneous cation-exchange MK-40 and anion-exchange MA-41 membranes were chosen as the initial membranes. Profiled membranes with three different [...] Read more.

Profiled ion-exchange membranes are promising for improving the parameters of reverse electrodialysis due to the reduction of pumping power and electrical resistance. The smooth commercial heterogeneous cation-exchange MK-40 and anion-exchange MA-41 membranes were chosen as the initial membranes. Profiled membranes with three different types of surface profiles were obtained by hot pressing the initial membranes. The bilayer membranes were made on the basis of single-layer profiled membranes by casting MF-4SK film on the profiled surfaces. The diffusion permeability of all types of single-layer and bilayer profiled membranes was higher than of the initial ones due to the appearance of large defects on their surface during pressing. The conductivity of the profiled membrane was lower in the diluted solution and higher in the concentrated solution than of the initial one for all samples except for the bilayer anion-exchange membrane. The conductivity of that sample was lower than that of the initial anion-exchange MA-41 membrane over the entire range of studied concentrations. The counter-ion transport numbers for all studied membranes were calculated based on the concentration dependences of conductivity and diffusion permeability of the membrane by the microheterogeneous model. The selectivity of single layer and bilayer profiled membranes became lower after their profiling due to the increase of the solution phases of membranes. The asymmetry of the current-voltage curves for all single-layer and bilayer profiled membranes was found. The application of the single layer and bilayer profiled membranes in reverse electrodialysis did not lead to an increase in power density. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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22 pages, 5908 KiB

Open AccessArticle

Animal Cellulose with Hierarchical Structure Isolated from Halocynthia aurantium Tunic as the Basis for High-Performance Pressure-Resistant Nanofiltration Membrane

by Svetlana V. Kononova, Albert K. Khripunov, Vladislav N. Romanov, Anton S. Orekhov, Alexey A. Mikhutkin, Elena N. Vlasova, Maxim S. Lukasov and Vera V. Klechkovskaya

Membranes 2022, 12(10), 975; https://doi.org/10.3390/membranes12100975 - 06 Oct 2022

Viewed by 1591

Abstract

The structure and transport properties of the new Cellokon-AKH membrane based on animal cellulose obtained from tunic of ascidian Halocynthia aurantium were studied. The results of scanning electron microscopy (SEM), FTIR spectroscopy, and the X-ray diffraction data revealed significant differences in the structure [...] Read more.

The structure and transport properties of the new Cellokon-AKH membrane based on animal cellulose obtained from tunic of ascidian Halocynthia aurantium were studied. The results of scanning electron microscopy (SEM), FTIR spectroscopy, and the X-ray diffraction data revealed significant differences in the structure and morphology of upper and lower surfaces of this layered film membrane based on animal cellulose. It was shown that the membrane surface is a network of intertwined cellulose fibers, with both denser and looser areas present on the lower surface compared to the completely uniform morphology of the main part of the upper surface. The hierarchical structure of tunicin-based outgrowths evenly distributed over the upper surface was determined and analyzed. The 3D visual representation of the surface structure was performed with the surface reconstruction technique using scanning electron microscope images. A surface model was calculated from the aligned images based on the photogrammetric approach. The transport properties of samples with different prehistory with respect to ethanol, water, and their mixtures of different compositions were studied depending on the pressure. Representing an alcohol-containing gel film in its original state, as solvents are removed, the membrane transforms into a low-permeability fibrillary organized selective film. The obtained results confirmed the possibility of using Cellokon-AKH (dried form) for the filtration of substances with a molecular weight of more than 600 Da in various media. Further study of this new material will allow to get closer to understanding the structure of the studied seabed inhabitants and to use these natural resources more efficiently. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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11 pages, 3004 KiB

Open AccessArticle

Ultra-Low Thermal Conductivity of Moiré Diamanes

by Suman Chowdhury, Victor A. Demin, Leonid A. Chernozatonskii and Alexander G. Kvashnin

Membranes 2022, 12(10), 925; https://doi.org/10.3390/membranes12100925 - 25 Sep 2022

Cited by 5 | Viewed by 1822

Abstract

Ultra-thin diamond membranes, diamanes, are one of the most intriguing quasi-2D films, combining unique mechanical, electronic and optical properties. At present, diamanes have been obtained from bi- or few-layer graphene in AA- and AB-stacking by full hydrogenation or fluorination. Here, we study the [...] Read more.

Ultra-thin diamond membranes, diamanes, are one of the most intriguing quasi-2D films, combining unique mechanical, electronic and optical properties. At present, diamanes have been obtained from bi- or few-layer graphene in AA- and AB-stacking by full hydrogenation or fluorination. Here, we study the thermal conductivity of diamanes obtained from bi-layer graphene with twist angle

θ

between layers forming a Moiré pattern. The combination of DFT calculations and machine learning interatomic potentials makes it possible to perform calculations of the lattice thermal conductivity of such diamanes with twist angles

θ

of 13.2

^{\circ}

, 21.8

^{\circ}

and 27.8

^{\circ}

using the solution of the phonon Boltzmann transport equation. Obtained results show that Moiré diamanes exhibit a wide variety of thermal properties depending on the twist angle, namely a sharp decrease in thermal conductivity from high for “untwisted” diamanes to ultra-low values when the twist angle tends to 30

^{\circ}

, especially for hydrogenated Moiré diamanes. This effect is associated with high anharmonicity and scattering of phonons related to a strong symmetry breaking of the atomic structure of Moiré diamanes compared with untwisted ones. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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0 pages, 3313 KiB

Open AccessArticle

The Transport Properties of Semi-Crystalline Polyetherimide BPDA-P3 in Amorphous and Ordered States: Computer Simulations

by Alexey Y. Dobrovskiy, Victor M. Nazarychev, Igor V. Volgin and Sergey V. Lyulin

Membranes 2022, 12(9), 856; https://doi.org/10.3390/membranes12090856 - 31 Aug 2022

Cited by 5 | Viewed by 1663 | Correction

Abstract

The effect of polymer chain ordering on the transport properties of the polymer membrane was examined for the semi-crystalline heterocyclic polyetherimide (PEI) BPDA-P3 based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and diamine 1,4-bis [4-(4-aminophenoxy)phenoxy]benzene (P3). All-atom Molecular Dynamics (MD) simulations were used to investigate the [...] Read more.

The effect of polymer chain ordering on the transport properties of the polymer membrane was examined for the semi-crystalline heterocyclic polyetherimide (PEI) BPDA-P3 based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and diamine 1,4-bis [4-(4-aminophenoxy)phenoxy]benzene (P3). All-atom Molecular Dynamics (MD) simulations were used to investigate the gas diffusion process carried out through the pores of a free volume several nanometers in size. The long-term (~30 μs) MD simulations of BPDA-P3 were performed at T = 600 K, close to the experimental value of the melting temperature (Tm ≈ 577 K). It was found during the simulations that the transition of the PEI from an amorphous state to an ordered one occurred. We determined a decrease in solubility for both gases examined (CO₂ and CH₄), caused by the redistribution of free volume elements occurring during the structural ordering of the polymer chains in the glassy state (Tg ≈ 487 K). By analyzing the diffusion coefficients in the ordered state, the presence of gas diffusion anisotropy was found. However, the averaged values of the diffusion coefficients did not differ from each other in the amorphous and ordered states. Thus, permeability in the observed system is primarily determined by gas solubility, rather than by gas diffusion. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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Review

Jump to: Research

27 pages, 8068 KiB

Open AccessReview

Recent Advances on Membranes for Water Purification Based on Carbon Nanomaterials

by Nikita S. Lazarenko, Valerii V. Golovakhin, Artem A. Shestakov, Nikita I. Lapekin and Alexander G. Bannov

Membranes 2022, 12(10), 915; https://doi.org/10.3390/membranes12100915 - 22 Sep 2022

Cited by 6 | Viewed by 3874

Abstract

Every year the problem of water purification becomes more relevant. This is due to the continuous increase in the level of pollution of natural water sources, an increase in the population, and sharp climatic changes. The growth in demand for affordable and clean [...] Read more.

Every year the problem of water purification becomes more relevant. This is due to the continuous increase in the level of pollution of natural water sources, an increase in the population, and sharp climatic changes. The growth in demand for affordable and clean water is not always comparable to the supply that exists in the water treatment market. In addition, the amount of water pollution increases with the increase in production capacity, the purification of which cannot be fully handled by conventional processes. However, the application of novel nanomaterials will enhance the characteristics of water treatment processes which are one of the most important technological problems. In this review, we considered the application of carbon nanomaterials in membrane water purification. Carbon nanofibers, carbon nanotubes, graphite, graphene oxide, and activated carbon were analyzed as promising materials for membranes. The problems associated with the application of carbon nanomaterials in membrane processes and ways to solve them were discussed. Their efficiency, properties, and characteristics as a modifier for membranes were analyzed. The potential directions, opportunities and challenges for application of various carbon nanomaterials were suggested. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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