Ionic Liquid-based Materials for Membrane Processes

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

Deadline for manuscript submissions: closed (29 February 2020) | Viewed by 20213

Special Issue Editors

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
LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Interests: ionic liquids; mixed matrix membranes; metal organic frameworks; gas separation; biopolymeric structures; biomedical applications

Special Issue Information

Dear Colleagues,

Large improvements in membrane separation processes require novel materials with enhanced properties and performances. During the last 20 years, Ionic Liquids (ILs) have blossomed as alternative materials to improve separation processes, offering a versatile and unique tuneable platform for the design of task-specific advanced membranes with a broad range of different chemical structures, physical/chemical properties, morphologies, and separation performances. The potential of using functional IL-based materials has been widely exploited through diverse morphologies and membrane configurations (flat or hollow-fibber) for applications such as gas separation, fuel cells, and water purification.

Bearing in mind that membrane engineering, together with materials science, plays a key role in the development of high-performance membranes and more efficient separation technologies, this Special Issue is devoted to recent advances in the fabrication, characterization, and application of membranes based on ILs, poly(ionic liquid)s, or other organic or inorganic materials containing ILs within their structure. Topics of interest include supported ionic liquid membranes (SILMs), polymer/ionic liquid composites, mixed matrix membranes, ion gels, porous membranes, metal organic frameworks supporting ionic liquids (ILs@MOFs), and membrane contactors or hollow fibbers. Special attention will be given to innovative material design strategies; their synthesis and characterization; the study of structure–performance relationships unveiling, for instance, the role of the IL-based material and morphology; as well as the development of new approaches for material processing and membrane fabrication.

We warmly invite you to submit your original work to this Special Issue. Modeling and experimental research articles, communication, as well as reviews dealing with innovative research advances are particularly welcome.

Dr. Liliana C. Tomé
Dr. Luísa A. Neves
Guest Editors

Manuscript Submission Information

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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

  • ionic liquids
  • poly(ionic liquids)
  • ILs@MOFs/COFs/POMs/PIMs
  • ion gels
  • supported ionic liquids
  • composites
  • mixed matrix membranes
  • gas separation
  • water purification
  • fuel cells
  • contactors

Published Papers (6 papers)

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Research

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11 pages, 1262 KiB  
Article
Acidic Gases Solubility in Bis(2-Ethylhexyl) Sulfosuccinate Based Ionic Liquids Using the Predictive Thermodynamic Model
Membranes 2020, 10(12), 429; https://doi.org/10.3390/membranes10120429 - 16 Dec 2020
Cited by 3 | Viewed by 1450
Abstract
To properly design ionic liquids (ILs) adopted for gases separation uses, a knowledge of ILs thermodynamic properties as well their solubilities with the gases is essential. In the present article, solubilities of CO2 and H2S in bis(2-Ethylhexyl)sulfosuccinate based ILs were [...] Read more.
To properly design ionic liquids (ILs) adopted for gases separation uses, a knowledge of ILs thermodynamic properties as well their solubilities with the gases is essential. In the present article, solubilities of CO2 and H2S in bis(2-Ethylhexyl)sulfosuccinate based ILs were predicted using the conductor like screening model for real solvents COSMO-RS. According to COSMO-RS calculations, the influence of the cation change was extensively analyzed. The obtained data are used for the prediction of adequate solvent candidates. Moreover, to understand the intrinsic behavior of gases solubility the free volume of the chosen ILs and their molecular interactions with respectively CO2 and H2S were computed. The results suggest that hydrogen bonding interactions in ILs and between ILs and the gases have a pivotal influence on the solubility. Full article
(This article belongs to the Special Issue Ionic Liquid-based Materials for Membrane Processes)
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24 pages, 6986 KiB  
Article
Ionic Polyureas—A Novel Subclass of Poly(Ionic Liquid)s for CO2 Capture
Membranes 2020, 10(9), 240; https://doi.org/10.3390/membranes10090240 - 18 Sep 2020
Cited by 8 | Viewed by 2639
Abstract
The growing concern for climate change and global warming has given rise to investigations in various research fields, including one particular area dedicated to the creation of solid sorbents for efficient CO2 capture. In this work, a new family of poly(ionic liquid)s [...] Read more.
The growing concern for climate change and global warming has given rise to investigations in various research fields, including one particular area dedicated to the creation of solid sorbents for efficient CO2 capture. In this work, a new family of poly(ionic liquid)s (PILs) comprising cationic polyureas (PURs) with tetrafluoroborate (BF4) anions has been synthesized. Condensation of various diisocyanates with novel ionic diamines and subsequent ion metathesis reaction resulted in high molar mass ionic PURs (Mw = 12 ÷ 173 × 103 g/mol) with high thermal stability (up to 260 °C), glass transition temperatures in the range of 153–286 °C and remarkable CO2 capture (10.5–24.8 mg/g at 0 °C and 1 bar). The CO2 sorption was found to be dependent on the nature of the cation and structure of the diisocyanate. The highest sorption was demonstrated by tetrafluoroborate PUR based on 4,4′-methylene-bis(cyclohexyl isocyanate) diisocyanate and aromatic diamine bearing quinuclidinium cation (24.8 mg/g at 0 °C and 1 bar). It is hoped that the present study will inspire novel design strategies for improving the sorption properties of PILs and the creation of novel effective CO2 sorbents. Full article
(This article belongs to the Special Issue Ionic Liquid-based Materials for Membrane Processes)
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15 pages, 2009 KiB  
Article
Synthesis and Performance of Aromatic Polyamide Ionenes as Gas Separation Membranes
Membranes 2020, 10(3), 51; https://doi.org/10.3390/membranes10030051 - 22 Mar 2020
Cited by 16 | Viewed by 4126
Abstract
Here, we report the synthesis and thermophysical properties of seven primarily aromatic, imidazolium-based polyamide ionenes. The effects of varied para-, meta-, and ortho-connectivity, and spacing of ionic and amide functional groups, on structural and thermophysical properties were analyzed. Suitable, robust [...] Read more.
Here, we report the synthesis and thermophysical properties of seven primarily aromatic, imidazolium-based polyamide ionenes. The effects of varied para-, meta-, and ortho-connectivity, and spacing of ionic and amide functional groups, on structural and thermophysical properties were analyzed. Suitable, robust derivatives were cast into thin films, neat, or with stoichiometric equivalents of the ionic liquid (IL) 1-benzy-3-methylimidazolium bistriflimide ([Bnmim][Tf2N]), and the gas transport properties of these membranes were measured. Pure gas permeabilities and permselectivities for N2, CH4, and CO2 are reported. Consistent para-connectivity in the backbone was shown to yield the highest CO2 permeability and suitability for casting as a very thin, flexible film. Derivatives containing terephthalamide segments exhibited the highest CO2/CH4 and CO2/N2 selectivities, yet CO2 permeability decreased with further deviation from consistent para-linkages. Full article
(This article belongs to the Special Issue Ionic Liquid-based Materials for Membrane Processes)
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18 pages, 3385 KiB  
Article
Influence of Anion Structure on Thermal, Mechanical and CO2 Solubility Properties of UV-Cross-Linked Poly(ethylene glycol) Diacrylate Iongels
Membranes 2020, 10(3), 46; https://doi.org/10.3390/membranes10030046 - 17 Mar 2020
Cited by 12 | Viewed by 3823
Abstract
Iongel-based CO2 separation membranes were prepared by fast (< 1 min) UV-initiated polymerization of poly(ethylene glycol) diacrylate (PEGDA) in the presence of different ionic liquids (ILs) with the [C2mim]+ cation and anions such as [TFSI], [FSI] [...] Read more.
Iongel-based CO2 separation membranes were prepared by fast (< 1 min) UV-initiated polymerization of poly(ethylene glycol) diacrylate (PEGDA) in the presence of different ionic liquids (ILs) with the [C2mim]+ cation and anions such as [TFSI], [FSI], [C(CN)3] and [B(CN)4]. The four ILs were completely miscible with the non-ionic PEGDA network. Transparent and free-standing iongels containing between 60 and 90 %wt of IL were obtained and characterized by diverse techniques (FTIR, TGA, DSC, DMTA, SEM, CO2 solubility and pure gas permeability). The thermal and mechanical stability of the iongels, as well as CO2 solubility, were found to be strictly dependent on the IL content and the anion’s nature. The TGA results indicated that the iongels mostly follow the thermal profile of the respective neat ILs. The DMTA analysis revealed that the iongels based on fluorinated anions have higher storage modulus than those of cyano-functionalized anions. Conversely, the PEGDA–C(CN)3 iongels presented the highest CO2 solubility values ranging from 72 to 80 mmol/g. Single CO2 permeabilities of 583 ± 29 Barrer and ideal CO2/N2 selectivities of 66 ± 3 were obtained with the PEGDA–70 C(CN)3 iongel membrane. This work demonstrates that the combination of PEGDA with high contents of the best performing ILs is a promising and simple strategy, opening up new possibilities in the design of high-performance iongel membranes for CO2 separation. Full article
(This article belongs to the Special Issue Ionic Liquid-based Materials for Membrane Processes)
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12 pages, 4392 KiB  
Article
Effects of Operating Parameters on Ionic Liquid Membrane to Remove Humidity in a Green Continuous Process
Membranes 2019, 9(5), 65; https://doi.org/10.3390/membranes9050065 - 24 May 2019
Cited by 3 | Viewed by 2891
Abstract
Membrane processes are promising methods to separate gases from feed streams without phase changing. A hybrid process, the combination of ionic liquids with a ceramic membrane (ILM), has been developed for humidity removal in a green continuous process. This new concept provides a [...] Read more.
Membrane processes are promising methods to separate gases from feed streams without phase changing. A hybrid process, the combination of ionic liquids with a ceramic membrane (ILM), has been developed for humidity removal in a green continuous process. This new concept provides a more efficient and available ionic liquid (IL)-based membrane regeneration process, which just switches the moist feed stream to dry air. Furthermore, the ILM presents high stability and mechanical resistance during long-time operation. In addition, the influences of several operating parameters, including flow rate, temperature, absolute pressure, and feed concentration on process efficiency were investigated. The lower inlet flow rate was found to be favorable for drying humid air. Moreover, when the pressure increased, the mass of absorbed water was increased, while the feed concentration had no significant effects on the membrane separation performance. However, the operating temperature had a great effect on humidity removal. It is necessary to note that the processes at room temperature can limit the energy consumption. The absorbing process of ILM remained efficient after several absorption desorption cycles. Therefore, the new ILM hybrid process that has been developed has great potential for consecutive humidity removal processes. Full article
(This article belongs to the Special Issue Ionic Liquid-based Materials for Membrane Processes)
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Review

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13 pages, 1200 KiB  
Review
Development and Application of Supported Ionic Liquid Membranes in Microbial Fuel Cell Technology: A Concise Overview
Membranes 2020, 10(1), 16; https://doi.org/10.3390/membranes10010016 - 18 Jan 2020
Cited by 29 | Viewed by 4515
Abstract
Membrane separators are key elements of microbial fuel cells (MFCs), especially of those constructed in a dual-chamber configuration. Until now, membranes made of Nafion have been applied the most widely to set-up MFCs. However, there is a broader agreement in the literature that [...] Read more.
Membrane separators are key elements of microbial fuel cells (MFCs), especially of those constructed in a dual-chamber configuration. Until now, membranes made of Nafion have been applied the most widely to set-up MFCs. However, there is a broader agreement in the literature that Nafion is expensive and in many cases, does not meet the actual (mainly mass transfer-specific) requirements demanded by the process and users. Driven by these issues, there has been notable progress in the development of alternative materials for membrane fabrication, among which those relying on the deployment of ionic liquids are emerging. In this review, the background of and recent advances in ionic liquid-containing separators, particularly supported ionic liquid membranes (SILMs), designed for MFC applications are addressed and evaluated. After an assessment of the basic criteria to be fulfilled by membranes in MFCs, experiences with SILMs will be outlined, along with important aspects of transport processes. Finally, a comparison with the literature is presented to elaborate on how MFCs installed with SILM perform relative to similar systems assembled with other, e.g., Nafion, membranes. Full article
(This article belongs to the Special Issue Ionic Liquid-based Materials for Membrane Processes)
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