Preparation and Application of Advanced Functional Membranes

A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Membrane Applications".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 18917

Special Issue Editors


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Guest Editor
Institute on Membrane Technology-Research National Council, CNR-ITM, 87036 Rende, Italy
Interests: advanced membranes manufacturing; nanomaterials; smart surfaces and coatings; green membrane technologies; sustainable solutions for water and environmental remediation; intelligent membranes for applications in textiles and cultural heritage assets; gels
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Guest Editor
Department of Civil, Chemical, Environmental and Materials Engineering, Alma Mater Studiorum-Università di Bologna, Via Terracini 34, 40128 Bologna, Italy
Interests: membrane separation processes; membrane chromatography; mixed matrix membranes; protein purification; bioseparations; ultrafiltration; membrane bioreactors
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It is claimed that membranes will bring a large number of benefits to the fields of water and environmental remediation, energy production and storage, transport and space, industry, agriculture and foods, health and biomedicine, as well as the automotive industry, fashion and textiles, architecture and cultural heritage. A high quality of life, healthcare, comfort, safety, protection, security and defense can be ensured through the implementation of sophisticated membrane technologies. However, the successful application of membrane processes depends largely on the properties of single membranes. High selectivity–productivity trade-offs and a broader dynamic range of sophisticated mechanisms of separation, recognition, transcription, transmission and recovery can have a strong impact during membrane processes. In recent years, the membrane concept has undergone a profound evolution, moving from traditional physical barriers to dynamic and interactive interfaces. Today, new membrane models are conceived as multicompartment arrays, where the interplay of complementary functions and high-defined volumetric spaces can be achieved through complex and multifaceted combinations of materials, which force the use of developed and sustainable practices based on a green manufacturing.

This Special Issue aims to bridge the gap between materials science, process technology and circular green transition rules through: a) the synthesis of new greener, natural and biodegradable materials with unusual properties and outstanding performances; b) the characterization and assessment of transport mechanisms; and c) innovative and smart applications. Membrane digitization is a further challenge that we currently face to make the membrane technology a positive choice consistent with the modern times and methods.

This Special Issue aims to gather the recent developments on: (i) ecofriendly practices for the fabrication of hybrid nanocomposite membranes, smart surfaces and coatings; (ii) computational studies and simulations; (iii) new tools for membrane characterization; (iv) strategies to control wetting and fouling events, molecular solubility, affinity and diffusion; (v) cooperative mechanisms for selective filtration, separation and conversion; (vi) integrated manufacturing and digitization membrane technologies; and (vii) groundbreaking and singular applications in every field.

The formats of research may include (but are not limited to) the following: original articles, reviews and mini-reviews, communications, comparative perspectives, and opinions.

We look forward to receiving your contributions.

Dr. Annarosa Gugliuzza
Dr. Cristiana Boi
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Membranes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • nanostructured functional membranes
  • responsive membranes
  • self-cleaning
  • self-healing and (bio-)repairing
  • water purification
  • air purification
  • environment
  • energy
  • modelling
  • monitoring

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Published Papers (12 papers)

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Research

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14 pages, 4280 KiB  
Article
Pathway for Water Transport through Breathable Nanocomposite Membranes of PEBAX with Ionic Liquid [C12C1im]Cl
by Ziqi Cheng, Shen Li, Elena Tocci, Giacomo Saielli, Annarosa Gugliuzza and Yanting Wang
Membranes 2023, 13(9), 749; https://doi.org/10.3390/membranes13090749 - 22 Aug 2023
Viewed by 776
Abstract
Water transport through membranes is an attractive topic among the research dedicated to dehydration processes, microenvironment regulation, or more simply, recovery of freshwater. Herein, an atomistic computer simulation is proposed to provide new insights about a water vapor transport mechanism through PEBAX membranes [...] Read more.
Water transport through membranes is an attractive topic among the research dedicated to dehydration processes, microenvironment regulation, or more simply, recovery of freshwater. Herein, an atomistic computer simulation is proposed to provide new insights about a water vapor transport mechanism through PEBAX membranes filled with ionic liquid (IL) [C12C1im]Cl. Starting from experimental evidence that indicates an effective increase in water permeation as the IL is added to the polymer matrix (e.g., up to 85·10−3 (g·m)/(m2·day) at 318.15 K for PEBAX@2533 membranes loaded with 70% of IL), molecular dynamics simulations are proposed to explore the key role of IL in water transport inside membranes. The polar region composed of anions and cationic head groups of the IL is demonstrated to serve as the pathway for water transport through the membrane. Water molecules always stay near the pathway, which becomes wider and thus has a larger water-accessible area with increasing IL concentration. Hence, the diffusion coefficients of water molecules and ions increase as the IL concentration increases. The simulation provides useful indications about a microscopic mechanism that regulates the transport of water vapor through a kind of PEBAX/IL membrane, resulting in full agreement with the experimental evidence. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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28 pages, 4981 KiB  
Article
Magnetic-Responsive Liposomal Hydrogel Membranes for Controlled Release of Small Bioactive Molecules—An Insight into the Release Kinetics
by Luís Pereira, Frederico Castelo Ferreira, Filipa Pires and Carla A. M. Portugal
Membranes 2023, 13(7), 674; https://doi.org/10.3390/membranes13070674 - 17 Jul 2023
Cited by 2 | Viewed by 1269
Abstract
This work explores the unique features of magnetic-responsive hydrogels to obtain liposomal hydrogel delivery platforms capable of precise magnetically modulated drug release based on the mechanical responses of these hydrogels when exposed to an external magnetic field. Magnetic-responsive liposomal hydrogel delivery systems were [...] Read more.
This work explores the unique features of magnetic-responsive hydrogels to obtain liposomal hydrogel delivery platforms capable of precise magnetically modulated drug release based on the mechanical responses of these hydrogels when exposed to an external magnetic field. Magnetic-responsive liposomal hydrogel delivery systems were prepared by encapsulation of 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) multilayered vesicles (MLVs) loaded with ferulic acid (FA), i.e., DPPC:FA liposomes, into gelatin hydrogel membranes containing dispersed iron oxide nanoparticles (MNPs), i.e., magnetic-responsive gelatin. The FA release mechanisms and kinetics from magnetic-responsive liposomal gelatin were studied and compared with those obtained with conventional drug delivery systems, e.g., free liposomal suspensions and hydrogel matrices, to access the effect of liposome entrapment and magnetic field on FA delivery. FA release from liposomal gelatin membranes was well described by the Korsmeyer–Peppas model, indicating that FA release occurred under a controlled diffusional regime, with or without magnetic stimulation. DPPC:FA liposomal gelatin systems provided smoother controlled FA release, relative to that obtained with the liposome suspensions and with the hydrogel platforms, suggesting the promising application of liposomal hydrogel systems in longer-term therapeutics. The magnetic field, with low intensity (0.08 T), was found to stimulate the FA release from magnetic-responsive liposomal gelatin systems, increasing the release rates while shifting the FA release to a quasi-Fickian mechanism. The magnetic-responsive liposomal hydrogels developed in this work offer the possibility to magnetically activate drug release from these liposomal platforms based on a non-thermal related delivery strategy, paving the way for the development of novel and more efficient applications of MLVs and liposomal delivery systems in biomedicine. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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17 pages, 3960 KiB  
Article
On the Performance of a Ready-to-Use Electrospun Sulfonated Poly(Ether Ether Ketone) Membrane Adsorber
by Niki Joosten, Weronika Wyrębak, Albert Schenning, Kitty Nijmeijer and Zandrie Borneman
Membranes 2023, 13(6), 543; https://doi.org/10.3390/membranes13060543 - 23 May 2023
Viewed by 1258
Abstract
Motivated by the need for efficient purification methods for the recovery of valuable resources, we developed a wire-electrospun membrane adsorber without the need for post-modification. The relationship between the fiber structure, functional-group density, and performance of electrospun sulfonated poly(ether ether ketone) (sPEEK) membrane [...] Read more.
Motivated by the need for efficient purification methods for the recovery of valuable resources, we developed a wire-electrospun membrane adsorber without the need for post-modification. The relationship between the fiber structure, functional-group density, and performance of electrospun sulfonated poly(ether ether ketone) (sPEEK) membrane adsorbers was explored. The sulfonate groups enable selective binding of lysozyme at neutral pH through electrostatic interactions. Our results show a dynamic lysozyme adsorption capacity of 59.3 mg/g at 10% breakthrough, which is independent of the flow velocity confirming dominant convective mass transport. Membrane adsorbers with three different fiber diameters (measured by SEM) were fabricated by altering the concentration of the polymer solution. The specific surface area as measured with BET and the dynamic adsorption capacity were minimally affected by variations in fiber diameter, offering membrane adsorbers with consistent performance. To study the effect of functional-group density, membrane adsorbers from sPEEK with different sulfonation degrees (52%, 62%, and 72%) were fabricated. Despite the increased functional-group density, the dynamic adsorption capacity did not increase accordingly. However, in all presented cases, at least a monolayer coverage was obtained, demonstrating ample functional groups available within the area occupied by a lysozyme molecule. Our study showcases a ready-to-use membrane adsorber for the recovery of positively charged molecules, using lysozyme as a model protein, with potential applications in removing heavy metals, dyes, and pharmaceutical components from process streams. Furthermore, this study highlights factors, such as fiber diameter and functional-group density, for optimizing the membrane adsorber’s performance. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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14 pages, 1627 KiB  
Article
Application of Hybrid Electrobaromembrane Process for Selective Recovery of Lithium from Cobalt- and Nickel-Containing Leaching Solutions
by Dmitrii Butylskii, Vasiliy Troitskiy, Daria Chuprynina, Lasâad Dammak, Christian Larchet and Victor Nikonenko
Membranes 2023, 13(5), 509; https://doi.org/10.3390/membranes13050509 - 11 May 2023
Cited by 3 | Viewed by 1057
Abstract
New processes for recycling valuable materials from used lithium-ion batteries (LIBs) need to be developed. This is critical to both meeting growing global demand and mitigating the electronic waste crisis. In contrast to the use of reagent-based processes, this work shows the results [...] Read more.
New processes for recycling valuable materials from used lithium-ion batteries (LIBs) need to be developed. This is critical to both meeting growing global demand and mitigating the electronic waste crisis. In contrast to the use of reagent-based processes, this work shows the results of testing a hybrid electrobaromembrane (EBM) method for the selective separation of Li+ and Co2+ ions. Separation is carried out using a track-etched membrane with a pore diameter of 35 nm, which can create conditions for separation if an electric field and an oppositely directed pressure field are applied simultaneously. It is shown that the efficiency of ion separation for a lithium/cobalt pair can be very high due to the possibility of directing the fluxes of separated ions to opposite sides. The flux of lithium through the membrane is about 0.3 mol/(m2 × h). The presence of coexisting nickel ions in the feed solution does not affect the flux of lithium. It is shown that the EBM separation conditions can be chosen so that only lithium is extracted from the feed solution, while cobalt and nickel remain in it. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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18 pages, 8424 KiB  
Article
Aliquots of MIL-140 and Graphene in Smart PNIPAM Mixed Hydrogels: A Nanoenvironment for a More Eco-Friendly Treatment of NaCl and Humic Acid Mixtures by Membrane Distillation
by Giuseppe Di Luca, Guining Chen, Wanqin Jin and Annarosa Gugliuzza
Membranes 2023, 13(4), 437; https://doi.org/10.3390/membranes13040437 - 17 Apr 2023
Cited by 1 | Viewed by 1468
Abstract
The problem of water scarcity is already serious and risks becoming dramatic in terms of human health as well as environmental safety. Recovery of freshwater by means of eco-friendly technologies is an urgent matter. Membrane distillation (MD) is an accredited green operation for [...] Read more.
The problem of water scarcity is already serious and risks becoming dramatic in terms of human health as well as environmental safety. Recovery of freshwater by means of eco-friendly technologies is an urgent matter. Membrane distillation (MD) is an accredited green operation for water purification, but a viable and sustainable solution to the problem needs to be concerned with every step of the process, including managed amounts of materials, membrane fabrication procedures, and cleaning practices. Once it is established that MD technology is sustainable, a good strategy would also be concerned with the choice of managing low amounts of functional materials for membrane manufacturing. These materials are to be rearranged in interfaces so as to generate nanoenvironments wherein local events, conceived to be crucial for the success and sustainability of the separation, can take place without endangering the ecosystem. In this work, discrete and random supramolecular complexes based on smart poly(N-isopropyl acrylamide) (PNIPAM) mixed hydrogels with aliquots of ZrO(O2C-C10H6-CO2) (MIL-140) and graphene have been produced on a polyvinylidene fluoride (PVDF) sublayer and have been proven to enhance the performance of PVDF membranes for MD operations. Two-dimensional materials have been adhered to the membrane surface through combined wet solvent (WS) and layer-by-layer (LbL) spray deposition without requiring further subnanometer-scale size adjustment. The creation of a dual responsive nanoenvironment has enabled the cooperative events needed for water purification. According to the MD’s rules, a permanent hydrophobic state of the hydrogels together with a great ability of 2D materials to assist water vapor diffusion through the membranes has been targeted. The chance to switch the density of charge at the membrane–aqueous solution interface has further allowed for the choice of greener and more efficient self-cleaning procedures with a full recovery of the permeation properties of the engineered membranes. The experimental evidence of this work confirms the suitability of the proposed approach to obtain distinct effects on a future production of reusable water from hypersaline streams under somewhat soft working conditions and in full respect to environmental sustainability. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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11 pages, 941 KiB  
Article
Lévy Flights Diffusion with Drift in Heterogeneous Membranes
by Anna Strzelewicz, Monika Krasowska and Michał Cieśla
Membranes 2023, 13(4), 417; https://doi.org/10.3390/membranes13040417 - 07 Apr 2023
Viewed by 1340
Abstract
The modelling of diffusion in membranes is essential to understanding transport processes through membranes, especially when it comes to improving process efficiency. The purpose of this study is to understand the relationship between membrane structures, external forces, and the characteristic features of diffusive [...] Read more.
The modelling of diffusion in membranes is essential to understanding transport processes through membranes, especially when it comes to improving process efficiency. The purpose of this study is to understand the relationship between membrane structures, external forces, and the characteristic features of diffusive transport. We investigate Cauchy flight diffusion with drift in heterogeneous membrane-like structures. The study focuses on numerical simulation of particle movement across different membrane structures with differently spaced obstacles. Four studied structures are similar to real polymeric membranes filled with inorganic powder, while the next three structures are designed to show which distribution of obstacles can cause changes in transport. The movement of particles driven by Cauchy flights is compared to a Gaussian random walk both with and without additional drift action. We show that effective diffusion in membranes with an external drift depends on the type of the internal mechanism that causes the movement of particles as well as on the properties of the environment. In general, when movement steps are provided by the long-tailed Cauchy distribution and the drift is sufficiently strong, superdiffusion is observed. On the other hand, strong drift can effectively stop Gaussian diffusion. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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22 pages, 5872 KiB  
Article
Bactericide Activity of Cellulose Acetate/Silver Nanoparticles Asymmetric Membranes: Surfaces and Porous Structures Role
by Ana Sofia Figueiredo, Ana Maria Ferraria, Ana Maria Botelho do Rego, Silvia Monteiro, Ricardo Santos, Miguel Minhalma, María Guadalupe Sánchez-Loredo, Rosa Lina Tovar-Tovar and Maria Norberta de Pinho
Membranes 2023, 13(1), 4; https://doi.org/10.3390/membranes13010004 - 21 Dec 2022
Cited by 5 | Viewed by 1471
Abstract
The antibacterial properties of cellulose acetate/silver nanoparticles (AgNP) ultrafiltration membranes were correlated with their integral asymmetric porous structures, emphasizing the distinct features of each side of the membranes, that is, the active and porous layers surfaces. Composite membranes were prepared from casting solutions [...] Read more.
The antibacterial properties of cellulose acetate/silver nanoparticles (AgNP) ultrafiltration membranes were correlated with their integral asymmetric porous structures, emphasizing the distinct features of each side of the membranes, that is, the active and porous layers surfaces. Composite membranes were prepared from casting solutions incorporating polyvinylpyrrolidone-covered AgNP using the phase inversion technique. The variation of the ratio acetone/formamide and the AgNP content resulted in a wide range of asymmetric porous structures with different hydraulic permeabilities. Comprehensive studies assessing the antibacterial activity against Escherichia coli (cell death and growth inhibition of bacteria in water) were performed on both membrane surfaces and in E. coli suspensions. The results were correlated with the surface chemical composition assessed by XPS. The silver-free membranes presented a generalized growth of E. coli, which is in contrast with the inhibition patterns displayed by the membranes containing AgNP. For the surface bactericide test, the growth inhibition depends on the accessibility of E. coli to the silver present in the membrane; as the XPS results show, the more permeable membranes (CA30 and CA34 series) have higher silver signal detected by XPS, which is correlated with a higher growth inhibition. On the other hand, the inhibition action is independent of the membrane porous structure when the membrane is deeply immersed in an E. coli inoculated suspension, presenting almost complete growth inhibition. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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13 pages, 17629 KiB  
Article
Functionalized GO Membranes for Efficient Separation of Acid Gases from Natural Gas: A Computational Mechanistic Understanding
by Quan Liu, Zhonglian Yang, Gongping Liu, Longlong Sun, Rong Xu and Jing Zhong
Membranes 2022, 12(11), 1155; https://doi.org/10.3390/membranes12111155 - 16 Nov 2022
Cited by 2 | Viewed by 1811
Abstract
Membrane separation technology is applied in natural gas processing, while a high-performance membrane is highly in demand. This paper considers the bright future of functionalized graphene oxide (GO) membranes in acid gas removal from natural gas. By molecular simulations, the adsorption and diffusion [...] Read more.
Membrane separation technology is applied in natural gas processing, while a high-performance membrane is highly in demand. This paper considers the bright future of functionalized graphene oxide (GO) membranes in acid gas removal from natural gas. By molecular simulations, the adsorption and diffusion behaviors of several unary gases (N2, CH4, CO2, H2S, and SO2) are explored in the 1,4-phenylenediamine-2-sulfonate (PDASA)-doped GO channels. Molecular insights show that the multilayer adsorption of acid gases evaluates well by the Redlich-Peterson model. A tiny amount of PDASA promotes the solubility coefficient of CO2 and H2S, respectively, up to 4.5 and 5.3 mmol·g−1·kPa−1, nearly 2.5 times higher than those of a pure GO membrane, which is due to the improved binding affinity, great isosteric heat, and hydrogen bonds, while N2 and CH4 only show single-layer adsorption with solubility coefficients lower than 0.002 mmol·g−1·kPa−1, and their weak adsorption is insusceptible to PDASA. Although acid gas diffusivity in GO channels is inhibited below 20 × 10−6 cm2·s−1 by PDASA, the solubility coefficient of acid gases is certainly high enough to ensure their separation efficiency. As a result, the permeabilities (P) of acid gases and their selectivities (α) over CH4 are simultaneously improved (PCO2 = 7265.5 Barrer, αCO2/CH4 = 95.7; P(H2S+CO2) = 42075.1 Barrer, αH2S/CH4 = 243.8), which outperforms most of the ever-reported membranes. This theoretical study gives a mechanistic understanding of acid gas separation and provides a unique design strategy to develop high-performance GO membranes toward efficient natural gas processing. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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10 pages, 1582 KiB  
Article
Etching and Doping of Pores in Polyethylene Terephthalate Analyzed by Ion Transmission Spectroscopy and Nuclear Depth Profiling
by Giovanni Ceccio, Jiri Vacik, Jakub Siegel, Antonino Cannavó, Andrey Choukourov, Pavel Pleskunov, Marco Tosca and Dietmar Fink
Membranes 2022, 12(11), 1061; https://doi.org/10.3390/membranes12111061 - 28 Oct 2022
Viewed by 1342
Abstract
This work is devoted to the study of controlled preparation and filling of pores in polyethylene terephthalate (PET) membranes. A standard wet chemical etching with different protocols (isothermal and isochronous etching for different times and temperatures and etching from one or both sides [...] Read more.
This work is devoted to the study of controlled preparation and filling of pores in polyethylene terephthalate (PET) membranes. A standard wet chemical etching with different protocols (isothermal and isochronous etching for different times and temperatures and etching from one or both sides of the films) was used to prepare the micrometric pores. The pores were filled with either a LiCl solution or boron deposited by magnetron sputtering. Subsequent control of the pore shape and dopant filling was performed using the nuclear methods of ion transmission spectroscopy (ITS) and neutron depth profiling (NDP). It turned out that wet chemical etching, monitored and quantified by ITS, was shown to enable the preparation of the desired simple pore geometry. Furthermore, the effect of dopant filling on the pore shape could be well observed and analyzed by ITS and, for relevant light elements, by NDP, which can determine their depth (and spatial) distribution. In addition, both non-destructive methods were proven to be suitable and effective tools for studying the preparation and filling of pores in thin films. Thus, they can be considered promising for research into nanostructure technologies of thin porous membranes. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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20 pages, 3177 KiB  
Article
Analysis of the Influence of Process Parameters on the Properties of Homogeneous and Heterogeneous Membranes for Gas Separation
by Daniel Polak and Maciej Szwast
Membranes 2022, 12(10), 1016; https://doi.org/10.3390/membranes12101016 - 19 Oct 2022
Cited by 3 | Viewed by 1659
Abstract
Heterogeneous membranes, otherwise known as Mixed Matrix Membranes (MMMs), which are used in gas separation processes, are the subject of growing interest. This is due to their potential to improve the process properties of membranes compared to those of homogeneous membranes, i.e., those [...] Read more.
Heterogeneous membranes, otherwise known as Mixed Matrix Membranes (MMMs), which are used in gas separation processes, are the subject of growing interest. This is due to their potential to improve the process properties of membranes compared to those of homogeneous membranes, i.e., those made of polymer only. Using such membranes in a process involves subjecting them to varying temperatures and pressures. This paper investigates the effects of temperature and feed pressure on the process properties of homogeneous and heterogeneous membranes. Membranes made of Pebax®2533 copolymer and containing additional fillers such as SiO2, ZIF−8, and POSS-Ph were investigated. Tests were performed over a temperature range of 25–55 °C and a pressure range of 2–8 bar for N2, CH4, and CO2 gases. It was found that temperature positively influences the increase in permeability, while pressure influences permeability depending on the gas used, which is related to the effect of pressure on the solubility of the gas in the membrane. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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Review

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34 pages, 5773 KiB  
Review
Thorium Removal, Recovery and Recycling: A Membrane Challenge for Urban Mining
by Geani Teodor Man, Paul Constantin Albu, Aurelia Cristina Nechifor, Alexandra Raluca Grosu, Szidonia-Katalin Tanczos, Vlad-Alexandru Grosu, Mihail-Răzvan Ioan and Gheorghe Nechifor
Membranes 2023, 13(9), 765; https://doi.org/10.3390/membranes13090765 - 29 Aug 2023
Cited by 1 | Viewed by 2819
Abstract
Although only a slightly radioactive element, thorium is considered extremely toxic because its various species, which reach the environment, can constitute an important problem for the health of the population. The present paper aims to expand the possibilities of using membrane processes in [...] Read more.
Although only a slightly radioactive element, thorium is considered extremely toxic because its various species, which reach the environment, can constitute an important problem for the health of the population. The present paper aims to expand the possibilities of using membrane processes in the removal, recovery and recycling of thorium from industrial residues reaching municipal waste-processing platforms. The paper includes a short introduction on the interest shown in this element, a weak radioactive metal, followed by highlighting some common (domestic) uses. In a distinct but concise section, the bio-medical impact of thorium is presented. The classic technologies for obtaining thorium are concentrated in a single schema, and the speciation of thorium is presented with an emphasis on the formation of hydroxo-complexes and complexes with common organic reagents. The determination of thorium is highlighted on the basis of its radioactivity, but especially through methods that call for extraction followed by an established electrochemical, spectral or chromatographic method. Membrane processes are presented based on the electrochemical potential difference, including barro-membrane processes, electrodialysis, liquid membranes and hybrid processes. A separate sub-chapter is devoted to proposals and recommendations for the use of membranes in order to achieve some progress in urban mining for the valorization of thorium. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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16 pages, 3052 KiB  
Review
Current and Potential Applications of Green Membranes with Nanocellulose
by Stefanos (Steve) Nitodas, Meredith Skehan, Henry Liu and Raj Shah
Membranes 2023, 13(8), 694; https://doi.org/10.3390/membranes13080694 - 25 Jul 2023
Cited by 2 | Viewed by 1179
Abstract
Large-scale applications of nanotechnology have been extensively studied within the last decade. By exploiting certain advantageous properties of nanomaterials, multifunctional products can be manufactured that can contribute to the improvement of everyday life. In recent years, one such material has been nanocellulose. Nanocellulose [...] Read more.
Large-scale applications of nanotechnology have been extensively studied within the last decade. By exploiting certain advantageous properties of nanomaterials, multifunctional products can be manufactured that can contribute to the improvement of everyday life. In recent years, one such material has been nanocellulose. Nanocellulose (NC) is a naturally occurring nanomaterial and a high-performance additive extracted from plant fibers. This sustainable material is characterized by a unique combination of exceptional properties, including high tensile strength, biocompatibility, and electrical conductivity. In recent studies, these unique properties of nanocellulose have been analyzed and applied to processes related to membrane technology. This article provides a review of recent synthesis methods and characterization of nanocellulose-based membranes, followed by a study of their applications on a larger scale. The article reviews successful case studies of the incorporation of nanocellulose in different types of membrane materials, as well as their utilization in water purification, desalination, gas separations/gas barriers, and antimicrobial applications, in an effort to provide an enhanced comprehension of their capabilities in commercial products. Full article
(This article belongs to the Special Issue Preparation and Application of Advanced Functional Membranes)
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