Special Issue "State-of-the-Art Membrane Science and Technology in the Iberian Peninsula 2021-2022"

A special issue of Membranes (ISSN 2077-0375).

Deadline for manuscript submissions: 25 December 2022 | Viewed by 8112

Special Issue Editors

Dr. Isabel Coelhoso
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Guest Editor
Department of Chemistry, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Interests: design of biopolymer membranes for biotechnology applications; biodegradable polymers and nanocomposites for food packaging
Special Issues, Collections and Topics in MDPI journals
Dr. Clara Casado-Coterillo
E-Mail Website
Guest Editor
Department of Chemical and Biomolecular Engineering, University of Cantabria, Av. Los Castros s/n, 39005 Santander, Spain
Interests: synthesis; characterization; CO2 capture and utilization; mixed matrix membranes; pervaporation; sustainable process intensification using membranes
Special Issues, Collections and Topics in MDPI journals
Dr. Diogo M.F. Santos
E-Mail Website
Guest Editor
Center of Physics and Engineering of Advanced Materials (CeFEMA), Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
Interests: low-temperature fuel cells; alkaline water electrolysis; electrochemical wastewater treatment
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Prof. Dr. José Ignacio Calvo
E-Mail Website
Guest Editor
Department of Applied Physics, Universidad de Valladolid, Palencia, Spain
Interests: membranes and porous materials; membrane processes; fouling; characterization of membranes and porous materials
Dr. Liliana C. Tomé
E-Mail Website
Guest Editor
LAQV/REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Interests: poly(ionic liquid)s; ionic liquids; gas separation; membranes; bio-based polymers; composites; ion gels; bioelectronic devices
Special Issues, Collections and Topics in MDPI journals
Dr. Svetlozar Velizarov
E-Mail Website
Guest Editor
Associate Laboratory for Green Chemistry (LAQV), Faculty of Science and Technology, New University of Lisbon, 2829-516 Caparica, Portugal.
Interests: clean (mainly membrane-assisted) (bio)chemical processes and technologies; electromembrane processes; water treatment; sustainable salinity gradient-based (“blue”) energy generation and/or storage
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Over the last few decades, considerable effort has been devoted to developing better membranes and extending their range of applications to different areas. Membrane processes already have an established role in gas separation and water treatment, and their applications in the food, pharmaceutical, and health areas have been continuously increasing.

In the last few years, membrane processes have proved to also have a key role in biorefinery and bioenergy production processes, namely for process intensification and the recovery and purification of valuable products. Membranes are also a crucial component of electrochemical energy conversion devices, including fuel cells and electrolyzers.

Moreover, the growing environmental concerns have drawn attention to the use of fossil-based polymers and toxic solvents for membrane fabrication. Therefore, the development of new membranes, using polymers from renewable sources and more sustainable methods of fabrication, is being pursued.

On the Iberian Peninsula, active membrane-related research is now being performed in a variety of domains, ranging from the production of clean water for potable use, agriculture and irrigation; the recovery of valuable compounds from natural sources and industrial effluents; and membrane reactors to energy generation and storage, as well as the integration of membranes and membrane technology in carbon capture and utilization strategies.

This issue aims to provide an overview of the trends and challenges in membrane processes and materials, involving Portuguese and Spanish researchers, as a contribution to a more sustainable water-energy–material–food nexus. The topics include but are not limited to emerging membrane-based technologies, innovative process design, modeling and validation, and lifecycle and techno-economic analysis. Both original papers and reviews are welcome.

Prof. Dr. Isabel Coelhoso
Dr. Clara Casado-Coterillo
Dr. Diogo Miguel Franco dos Santos
Prof. Dr. José Ignacio Calvo
Dr. Liliana C. Tomé
Dr. Svetlozar Velizarov
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 2200 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

  • membrane processes
  • process intensification
  • (bio)economy
  • renewable sources
  • sustainability
  • circular economy
  • water and wastewater treatment
  • advanced oxidation processes
  • membrane (bio)reactors
  • process modeling
  • hybrid processes
  • CO2 capture and utilization
  • membranes for fuel cells and electrolyzers
  • ionic liquid-based materials
  • gas separation
  • new membranes characterization

Published Papers (13 papers)

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Research

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Article
Membrane Dialysis for Partial Dealcoholization of White Wines
Membranes 2022, 12(5), 468; https://doi.org/10.3390/membranes12050468 - 26 Apr 2022
Viewed by 337
Abstract
Membrane dialysis is studied as a promising technique for partial dealcoholization of white wines. The performance of three membrane processes applied for the partial dealcoholization of white wines of the Verdejo variety has been studied in the present work. Combination of Nanofiltration with [...] Read more.
Membrane dialysis is studied as a promising technique for partial dealcoholization of white wines. The performance of three membrane processes applied for the partial dealcoholization of white wines of the Verdejo variety has been studied in the present work. Combination of Nanofiltration with Pervaporation, single step Pervaporation and, finally, Dialysis, have been applied to white wines from same variety and different vintages. The resulting wines have been chemically and sensorially analyzed and results have been compared with initial characteristics of the wines. From the results obtained, we can conclude that all procedures lead to significant alcohol content reduction (2%, 0.9% and 1.23% v/v respectively). Nevertheless, the best procedure consists in the application of Dialysis to the wines which resulted in a reasonable alcohol content reduction while maintaining organoleptic properties (only 14 consumers were able to distinguish the filtered and original wines, with 17 consumers needed to be this differences significant) and consumer acceptability of the original wine. Therefore, membrane dialysis, as a method of partial dealcoholization of white wines, has undoubted advantages over other techniques based on membranes, which must be confirmed in subsequent studies under more industrial conditions. This work represents the first application of Dialysis for the reduction of alcohol content in wines. Full article
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Article
Flat PVDF Membrane with Enhanced Hydrophobicity through Alkali Activation and Organofluorosilanisation for Dissolved Methane Recovery
Membranes 2022, 12(4), 426; https://doi.org/10.3390/membranes12040426 - 15 Apr 2022
Viewed by 414
Abstract
A three-step surface modification consisting of activation with NaOH, functionalisation with a silica precursor and organofluorosilane mixture (FSiT), and curing was applied to a poly(vinylidene fluoride) (PVDF) membrane for the recovery of dissolved methane (D-CH4) from aqueous streams. Based [...] Read more.
A three-step surface modification consisting of activation with NaOH, functionalisation with a silica precursor and organofluorosilane mixture (FSiT), and curing was applied to a poly(vinylidene fluoride) (PVDF) membrane for the recovery of dissolved methane (D-CH4) from aqueous streams. Based on the results of a statistical experimental design, the main variables affecting the water contact angle (WCA) were the NaOH concentration and the FSiT ratio and concentration used. The maximum WCA of the modified PVDF (mPVDFmax) was >140° at a NaOH concentration of 5%, an FSiT ratio of 0.55 and an FSiT concentration of 7.2%. The presence of clusters and a lower surface porosity of mPVDF was detected by FESEM analysis. In long-term stability tests with deionised water at 21 L h−1, the WCA of the mPVDF decreased rapidly to around 105°, similar to that of pristine nmPVDF. In contrast, the WCA of the mPVDF was always higher than that of nmPVDF in long-term operation with an anaerobic effluent at 3.5 L h−1 and showed greater mechanical stability, since water breakthrough was detected only with the nmPVDF membrane. D-CH4 degassing tests showed that the increase in hydrophobicity induced by the modification procedure increased the D-CH4 removal efficiency but seemed to promote fouling. Full article
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Article
A Novel Methodology to Obtain the Mechanical Properties of Membranes by Means of Dynamic Tests
Membranes 2022, 12(3), 288; https://doi.org/10.3390/membranes12030288 - 02 Mar 2022
Viewed by 426
Abstract
A new, non-destructive methodology is proposed in this work in order to determine the mechanical properties of membrane using vibro-acoustic tests. This procedure is based on the dynamic analysis of the behavior of the membrane. When the membrane is subjected to a sound [...] Read more.
A new, non-destructive methodology is proposed in this work in order to determine the mechanical properties of membrane using vibro-acoustic tests. This procedure is based on the dynamic analysis of the behavior of the membrane. When the membrane is subjected to a sound excitation it responds by vibrating based on its modal characteristics and this modal parameter is directly related to its mechanical properties. The paper is structured in two parts. First, the theoretical bases of the test are presented. The interaction between the sound waves and the membrane (mechano-acoustic coupling) is complex and requires meticulous study. It was broadly studied by means of numerical simulations. A summary of this study is shown. Aspects, such as the position of the sound source, the measuring points, the dimensions of the membrane, the frequency range, and the magnitudes to be measured, among others, were evaluated. The validity of modal analysis curve-fitting techniques to extract the modal parameter from the data measures was also explored. In the second part, an experimental test was performed to evaluate the validity of the method. A membrane of the same material with three different diameters was measured with the aim of estimating the value of the Young’s modulus. The procedure was applied and satisfactory results were obtained. Additionally, the experiment shed light on aspects that must be taken account in future experiments. Full article
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Article
New Insights on the Effects of Water on Polymer Inclusion Membranes Containing Aliquat 336 Derivatives as Carriers
Membranes 2022, 12(2), 192; https://doi.org/10.3390/membranes12020192 - 05 Feb 2022
Viewed by 341
Abstract
Surface characterization of polymer inclusion membranes (PIMs) using the polymers cellulose triacetate and polyvinyl chloride, containing different ionic liquids (ILs) as carriers, has been performed. Three different ILs have been tested: commercial trioctyl methylammonium chloride (Aliquat 336–AlqCl) and two derivatives bearing [...] Read more.
Surface characterization of polymer inclusion membranes (PIMs) using the polymers cellulose triacetate and polyvinyl chloride, containing different ionic liquids (ILs) as carriers, has been performed. Three different ILs have been tested: commercial trioctyl methylammonium chloride (Aliquat 336–AlqCl) and two derivatives bearing the counter anion NO3 or SCN (AlqNO3 and AlqSCN, respectively). Surface analysis was performed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) for both dry membranes and PIMs immersed for 4 days in ultrapure water to investigate the effect of the interaction of water with the membrane’s morphology and composition. XPS analysis of the PIMs revealed that immersion in ultrapure water causes a decrease in the atomic concentration percentage (A.C.%) of the specific IL atoms (Cl, S, and N) when compared with dry samples. Moreover, SEM images of the PIMs containing the IL AlqNO3 showed an alteration in the morphology of the membrane due to water contact at surface level, whereas no changes were observed at a bulk level. These changes in the surface composition of the water equilibrated PIMs may be associated with the solubilization of the IL in the water solution, which, therefore, may affect the reactivity of the membrane’s surface. To better understand this effect, PIMs containing both AlqCl and AlqNO3 as carriers were used for arsenic (V) transport. It was found that AlqCl was the most effective IL and that the effectivity of the PIM on As(V) removal was not affected after five cycles of the membrane’s reuse. Full article
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Article
Nitrate Removal by Donnan Dialysis and Anion-Exchange Membrane Bioreactor Using Upcycled End-of-Life Reverse Osmosis Membranes
Membranes 2022, 12(2), 101; https://doi.org/10.3390/membranes12020101 - 18 Jan 2022
Cited by 1 | Viewed by 530
Abstract
This work explores the application of Reverse Osmosis (RO) upcycled membranes, as Anion Exchange Membranes (AEMs) in Donnan Dialysis (DD) and related processes, such as the Ion Exchange Membrane Bioreactor (IEMB), for the removal of nitrate from contaminated water, to meet drinking water [...] Read more.
This work explores the application of Reverse Osmosis (RO) upcycled membranes, as Anion Exchange Membranes (AEMs) in Donnan Dialysis (DD) and related processes, such as the Ion Exchange Membrane Bioreactor (IEMB), for the removal of nitrate from contaminated water, to meet drinking water standards. Such upcycled membranes might be manufactured at a lower price than commercial AEMs, while their utilization reinforces the commitment to a circular economy transition. In an effort to gain a better understanding of such AEMs, confocal µ-Raman spectroscopy was employed, to assess the distribution of the ion-exchange sites through the thickness of the prepared membranes, and 2D fluorescence spectroscopy, to evaluate alterations in the membranes caused by fouling and chemical cleaning The best performing membrane reached a 56% average nitrate removal within 24 h in the DD and IEMB systems, with the latter furthermore allowing for simultaneous elimination of the pollutant by biological denitrification, thus avoiding its discharge into the environment. Overall, this work validates the technical feasibility of using RO upcycled AEMs in DD and IEMB processes for nitrate removal. This membrane recycling concept might also find applications for the removal and/or recovery of other target negatively charged species. Full article
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Article
Assessment of the Potential of Using Nanofiltration Polymeric and Ceramic Membranes to Treat Refinery Spent Caustic Effluents
Membranes 2022, 12(1), 98; https://doi.org/10.3390/membranes12010098 - 17 Jan 2022
Viewed by 362
Abstract
Spent caustic effluents are very challenging due to their very hazardous nature in terms of toxicity as well as their extreme pH (approximately 12–14). Spent caustic has presented a challenge for wastewater treatment in refineries, due to its composition rich in mercaptans, sulfides [...] Read more.
Spent caustic effluents are very challenging due to their very hazardous nature in terms of toxicity as well as their extreme pH (approximately 12–14). Spent caustic has presented a challenge for wastewater treatment in refineries, due to its composition rich in mercaptans, sulfides and other aromatic compounds. To address such problems, membrane filtration was studied using real effluents from Sines Refinery, in Portugal. The present study attempts to assess the potential for spent caustic treatment with nanofiltration (NF) polymeric and ceramic membranes, assessing membrane life expectancy. For that, membrane aging studies in static mode were performed with the polymeric membrane before attempting NF treatment (dynamic studies). A ceramic membrane was also tested for the first time with this type of effluents, though only in dynamic mode. Although the polymeric membrane performance was very good and in accordance with previous studies, its lifespan was very reduced after 6 weeks of contact with spent caustic, compromising its use in an industrial unit. Contrarily to expectations, the ceramic membrane tested was not chemically more resistant than the polymeric one upon direct contact with spent caustic (loss of retention capacity in less than 1 h in contact with the spent caustic). The results obtained suggest that a pH of 13.9 is very aggressive, even for ceramic membranes. Full article
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Article
Low-Temperature Hydrophilic Pervaporation of Lactic Acid Esterification Reaction Media
Membranes 2022, 12(1), 96; https://doi.org/10.3390/membranes12010096 - 17 Jan 2022
Viewed by 287
Abstract
Esterification reactions show a limited conversion due to the presence of water, which favors the opposite reaction. The removal of water from the reaction mixture increases the production of the ester. Pervaporation is an effective dehydration technique, usually applied to binary mixtures. The [...] Read more.
Esterification reactions show a limited conversion due to the presence of water, which favors the opposite reaction. The removal of water from the reaction mixture increases the production of the ester. Pervaporation is an effective dehydration technique, usually applied to binary mixtures. The effect on pervaporation of a reactive multicomponent system involving water, ethanol, ethyl lactate and lactic acid with high acid concentration (13.5 wt. %) at relatively low temperatures (40–80 °C) was studied. Three hydrophilic membranes mainly fabricated for dehydration purposes from Sulzer Chemtech were used, i.e., PERVAP™ 3100, PERVAP™ 2216 and PERVAP™ 1131. The last one revealed as the most suitable for the application and it was further characterized with binary and ternary solutions. The membrane showed high affinity for the lactic acid. The acid permeation played a key role in the water/ethanol and water/ethyl lactate selectivity. Lactic acid permeates and crystalizes in the permeate side of the membrane at very low water concentration (below 2 wt. %), causing a drop in flux and membrane selectivity. Ethyl lactate is responsible of the loss of integrity of the membranes. Full article
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Article
Feasibility of Adsorption Kinetic Models to Study Carrier-Mediated Transport of Heavy Metal Ions in Emulsion Liquid Membranes
Membranes 2022, 12(1), 66; https://doi.org/10.3390/membranes12010066 - 03 Jan 2022
Viewed by 250
Abstract
Emulsion liquid membranes have been successfully used for the removal of different types of organic and inorganic pollutants by means of carrier-mediated transport mechanisms. However, the models that describe the kinetics and transport of such mechanisms are very complex due to the high [...] Read more.
Emulsion liquid membranes have been successfully used for the removal of different types of organic and inorganic pollutants by means of carrier-mediated transport mechanisms. However, the models that describe the kinetics and transport of such mechanisms are very complex due to the high number of model parameters. Starting from an analysis of the similarity between the elemental mechanisms of carrier-mediated transport in liquid membranes and of transport in adsorption processes, this paper presents an experimental analysis of the possibility of applying kinetic and mechanistic models developed for adsorption to carrier-mediated transport in emulsion liquid membranes. We study the removal of a target species, in this case, Cu(II), by emulsion liquid membranes containing membrane phase solutions of benzoylacetone (carrier agent), Span 80 (emulsifying agent) and kerosene (diluent), and hydrochloric acid as a stripping agent in the product phase. The experimental results fit the pseudo-second-order adsorption kinetic model, showing good relationships between the experimental and model parameters. Although both Cu(II) diffusion through the feed/membrane interface boundary layer and complex Cu-benzoylacetone diffusion through the membrane phase controls Cu(II) transport, it is the former step that mainly controls the transport process. Full article
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Article
Separation Iron(III)-Manganese(II) via Supported Liquid Membrane Technology in the Treatment of Spent Alkaline Batteries
Membranes 2021, 11(12), 991; https://doi.org/10.3390/membranes11120991 - 19 Dec 2021
Viewed by 895
Abstract
In this paper, the transport of iron(III) from iron(III)-manganese(II)-hydrochloric acid mixed solutions, coming from the treatment of spent alkaline batteries through a flat-sheet supported liquid membrane, is investigated (the carrier phase being of Cyanex 923 (commercially available phosphine oxide extractant) dissolved in Solvesso [...] Read more.
In this paper, the transport of iron(III) from iron(III)-manganese(II)-hydrochloric acid mixed solutions, coming from the treatment of spent alkaline batteries through a flat-sheet supported liquid membrane, is investigated (the carrier phase being of Cyanex 923 (commercially available phosphine oxide extractant) dissolved in Solvesso 100 (commercially available diluent)). Iron(III) transport is studied as a function of hydrodynamic conditions, the concentration of manganese and HCl in the feed phase, and the carrier concentration in the membrane phase. A transport model is derived that describes the transport mechanism, consisting of diffusion through a feed aqueous diffusion layer, a fast interfacial chemical reaction, and diffusion of the iron(III) species-Cyanex 923 complex across the membrane phase. The membrane diffusional resistance (Δm) and feed diffusional resistance (Δf) are calculated from the model, and their values are 145 s/cm and 361 s/cm, respectively. It is apparent that the transport of iron(III) is mainly controlled by diffusion through the aqueous feed boundary layer, this being the thickness of this layer calculated as 2.9 × 10−3 cm. Since manganese(II) is not transported through the membrane phase, the present system allows the purification of these manganese-bearing solutions. Full article
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Article
Reduction of Cost and Environmental Impact in the Treatment of Textile Wastewater Using a Combined MBBR-MBR System
Membranes 2021, 11(11), 892; https://doi.org/10.3390/membranes11110892 - 19 Nov 2021
Viewed by 628
Abstract
A hybrid Moving Bed Biofilm Reactor—Membrane Bioreactor (MBBR-MBR) was developed for the treatment of wastewater from a Spanish textile company. Compared with conventional activated sludge (CAS) treatment, the feasibility of this hybrid system to reduce economic and environmental impact on an industrial scale [...] Read more.
A hybrid Moving Bed Biofilm Reactor—Membrane Bioreactor (MBBR-MBR) was developed for the treatment of wastewater from a Spanish textile company. Compared with conventional activated sludge (CAS) treatment, the feasibility of this hybrid system to reduce economic and environmental impact on an industrial scale was conducted. The results showed that, technically, the removal efficiency of COD, TSS and color reached 93%, 99% and 85%, respectively. The newly dyed fabrics performed with the treated wastewater were qualified under the standards of the textile industry. Economically, the values of Capital Expenditure (CAPEX) calculated for the hybrid MBBR-MBR system are profitable because of the reduction in Operational Expenditure (OPEX) when compared with CAS treatment, due to the lower effluent discharge tax thanks to the higher quality of the effluent and the decolorizing agent saved. The result of Net Present Value (NPV) and the Internal Rate of Return (IRR) of 18% suggested that MBBR-MBR is financially applicable for implantation into the industrial scale. The MBBR-MBR treatment also showed lower environmental impacts than the CAS process in the life cycle assessment (LCA) study, especially in the category of climate change, thanks to the avoidance of using extra decolorizing agent, a synthetic product based on a triamine. Full article
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Article
Novel Cellulose Acetate-Based Monophasic Hybrid Membranes for Improved Blood Purification Devices: Characterization under Dynamic Conditions
Membranes 2021, 11(11), 825; https://doi.org/10.3390/membranes11110825 - 27 Oct 2021
Cited by 3 | Viewed by 771
Abstract
A novel cellulose acetate-based monophasic hybrid skinned amine-functionalized CA-SiO2-(CH2)3NH2 membrane was synthesized using an innovative method which combines the phase inversion and sol-gel techniques. Morphological characterization was performed by scanning electron microscopy (SEM), and the chemical [...] Read more.
A novel cellulose acetate-based monophasic hybrid skinned amine-functionalized CA-SiO2-(CH2)3NH2 membrane was synthesized using an innovative method which combines the phase inversion and sol-gel techniques. Morphological characterization was performed by scanning electron microscopy (SEM), and the chemical composition was analyzed by Fourier transform infrared spectroscopy in attenuated total reflection mode (ATR-FTIR). The characterization of the monophasic hybrid CA-SiO2-(CH2)3NH2 membrane in terms of permeation properties was carried out in an in-house-built single hemodialysis membrane module (SHDMM) under dynamic conditions. Permeation experiments were performed to determine the hydraulic permeability (Lp), molecular weight cut-off (MWCO) and the rejection coefficients to urea, creatinine, uric acid, and albumin. SEM confirmed the existence of a very thin (<1 µm) top dense layer and a much thicker bottom porous surface, and ATR-FTIR showed the main bands belonging to the CA-based membranes. Permeation studies revealed that the Lp and MWCO of the CA-SiO2-(CH2)3NH2 membrane were 66.61 kg·h−1·m−2·bar−1 and 24.5 kDa, respectively, and that the Lp was 1.8 times higher compared to a pure CA membrane. Furthermore, the CA-SiO2-(CH2)3NH2 membrane fully permeated urea, creatinine, and uric acid while completely retaining albumin. Long-term filtration studies of albumin solutions indicated that fouling does not occur at the surface of the CA-SiO2-(CH2)3NH2 membrane. Full article
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Review

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Review
Overview of Membrane Science and Technology in Portugal
Membranes 2022, 12(2), 197; https://doi.org/10.3390/membranes12020197 - 08 Feb 2022
Viewed by 741
Abstract
Membrane research in Portugal is aligned with global concerns and expectations for sustainable social development, thus progressively focusing on the use of natural resources and renewable energy. This review begins by addressing the pioneer work on membrane science and technology in Portugal by [...] Read more.
Membrane research in Portugal is aligned with global concerns and expectations for sustainable social development, thus progressively focusing on the use of natural resources and renewable energy. This review begins by addressing the pioneer work on membrane science and technology in Portugal by the research groups of Instituto Superior TécnicoUniversidade de Lisboa (IST), NOVA School of Science and TechnologyUniversidade Nova de Lisboa (FCT NOVA) and Faculdade de EngenhariaUniversidade do Porto (FEUP) aiming to provide an historical perspective on the topic. Then, an overview of the trends and challenges in membrane processes and materials, mostly in the last five years, involving Portuguese researchers, is presented as a contribution to a more sustainable water–energy–material–food nexus. Full article
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Review
Past, Present and Future of Membrane Technology in Spain
Membranes 2021, 11(11), 808; https://doi.org/10.3390/membranes11110808 - 24 Oct 2021
Viewed by 826
Abstract
The following review aims at analyzing the contribution of Spanish researchers to membrane science and technology, with a historical compilation of the main milestones. We used a bibliometric analysis based on the Scopus database (1960–2020) dealing with 8707 documents covering the different disciplines [...] Read more.
The following review aims at analyzing the contribution of Spanish researchers to membrane science and technology, with a historical compilation of the main milestones. We used a bibliometric analysis based on the Scopus database (1960–2020) dealing with 8707 documents covering the different disciplines and subject areas where membranes are involved. Furthermore, the information has been updated to the present moment of writing this manuscript in order to include the latest research lines and the different research groups currently active in Spain, which may lead the way to the development of the field in the coming years. Full article
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: A novel methodology to obtain the mechanical properties of membranes by means of dynamic tests

Authorship: Antonia Lima-Rodriguez, Jose Garcia-Manrique, Wei Dong, and Antonio Gonzalez-Herrera

Abstract: A new non-destructive methodology is proposed in this work in order to determine the mechanical properties of membranes using vibro-acoustic tests. This procedure is based on the dynamic analysis of the behavior of the membrane. When the membrane is subjected to a sound excitation it responds vibrating based on its modal characteristics and this modal parameter are directly related to its mechanical properties.

The paper is structured in two parts. In the first one, the theoretical bases of the test are presented. The interaction between the sound waves and the membrane (mechano-acoustic coupling) is complex and requires a meticulous study. It has been broadly studied by means of numerical simulations. A summary of this study is shown. Aspects as the position of the sound source, the measuring points, the dimensions of the membrane, the frequency range, or the magnitudes to be measured, among others has been evaluated. The validity of modal analysis curve-fitting techniques to extract the modal parameter from the data measures has also been explored. 

In the second part, an experimental test has been performed to evaluate the validity of the method. A membrane of the same material with three different diameters has been measured with the aim to estimate the value of the Young Modulus. The procedure has been applied and satisfactory results have been obtained. Additionally, the experiment shed light on aspects that must be taken account on future experiments.

Keywords: membrane characterization; experiment; finite element model

 

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