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Membranes, Volume 2, Issue 3 (September 2012), Pages 346-686

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Research

Jump to: Review

Open AccessArticle Pure and Modified Co-Poly(amide-12-b-ethylene oxide) Membranes for Gas Separation Studied by Molecular Investigations
Membranes 2012, 2(3), 346-366; doi:10.3390/membranes2030346
Received: 24 May 2012 / Revised: 5 June 2012 / Accepted: 13 June 2012 / Published: 28 June 2012
Cited by 3 | PDF Full-text (733 KB) | HTML Full-text | XML Full-text
Abstract
This paper deals with a theoretical investigation of gas transport properties in a pure and modified PEBAX block copolymer membrane with N-ethyl-o/p-toluene sulfonamide (KET) as additive molecules. Molecular dynamics simulations using COMPASS force field, Gusev-Suter Transition State Theory (TST) and Monte Carlo
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This paper deals with a theoretical investigation of gas transport properties in a pure and modified PEBAX block copolymer membrane with N-ethyl-o/p-toluene sulfonamide (KET) as additive molecules. Molecular dynamics simulations using COMPASS force field, Gusev-Suter Transition State Theory (TST) and Monte Carlo methods were used. Bulk models of PEBAX and PEBAX/KET in different copolymer/additive compositions were assembled and analyzed to evaluate gas permeability and morphology to characterize structure-performance relationships. Full article
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Open AccessArticle A Composite Membrane of Caesium Salt of Heteropolyacids/Quaternary Diazabicyclo-Octane Polysulfone with Poly (Tetrafluoroethylene) for Intermediate Temperature Fuel Cells
Membranes 2012, 2(3), 384-394; doi:10.3390/membranes2030384
Received: 8 May 2012 / Revised: 7 June 2012 / Accepted: 28 June 2012 / Published: 10 July 2012
Cited by 1 | PDF Full-text (647 KB) | HTML Full-text | XML Full-text
Abstract
Inorganic-organic composite electrolyte membranes were fabricated from CsXH3−XPMo12O40 (CsPOMo) and quaternary diazabicyclo-octane polysulfone (QDPSU) using a polytetrafluoroethylene (PTFE) porous matrix for the application of intermediate temperature fuel cells. The CsPOMo/QDPSU/PTFE composite membrane was made proton conducting
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Inorganic-organic composite electrolyte membranes were fabricated from CsXH3−XPMo12O40 (CsPOMo) and quaternary diazabicyclo-octane polysulfone (QDPSU) using a polytetrafluoroethylene (PTFE) porous matrix for the application of intermediate temperature fuel cells. The CsPOMo/QDPSU/PTFE composite membrane was made proton conducting by using a relatively low phosphoric acid loading, which benefits the stability of the membrane conductivity and the mechanical strength. The casting method was used in order to build a thin and robust composite membrane. The resulting composite membrane films were characterised in terms of the elemental composition, membrane structure and morphology by EDX, FTIR and SEM. The proton conductivity of the membrane was 0.04 S cm−1 with a H3PO4 loading level of 1.8 PRU (amount of H3PO4 per repeat unit of polymer QDPSU). The fuel cell performance with the membrane gave a peak power density of 240 mW cm−2 at 150 °C and atmospheric pressure. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle Effectiveness of Water Desalination by Membrane Distillation Process
Membranes 2012, 2(3), 415-429; doi:10.3390/membranes2030415
Received: 13 June 2012 / Revised: 2 July 2012 / Accepted: 5 July 2012 / Published: 17 July 2012
Cited by 15 | PDF Full-text (1311 KB) | HTML Full-text | XML Full-text
Abstract
The membrane distillation process constitutes one of the possibilities for a new method for water desalination. Four kinds of polypropylene membranes with different diameters of capillaries and pores, as well as wall thicknesses were used in studied. The morphology of the membrane used
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The membrane distillation process constitutes one of the possibilities for a new method for water desalination. Four kinds of polypropylene membranes with different diameters of capillaries and pores, as well as wall thicknesses were used in studied. The morphology of the membrane used and the operating parameters significantly influenced process efficiency. It was found that the membranes with lower wall thickness and a larger pore size resulted in the higher yields. Increasing both feed flow rate and temperature increases the permeate flux and simultaneously the process efficiency. However, the use of higher flow rates also enhanced heat losses by conduction, which decreases the thermal efficiency. This efficiency also decreases when the salt concentration in the feed was enhanced. The influence of fouling on the process efficiency was considered. Full article
(This article belongs to the Special Issue Energy Efficient Membranes)
Open AccessArticle Poly(imide)/Organically-Modified Montmorillonite Nanocomposite as a Potential Membrane for Alkaline Fuel Cells
Membranes 2012, 2(3), 430-439; doi:10.3390/membranes2030430
Received: 7 May 2012 / Revised: 19 June 2012 / Accepted: 4 July 2012 / Published: 18 July 2012
Cited by 5 | PDF Full-text (1080 KB) | HTML Full-text | XML Full-text
Abstract
In this work we evaluated the potentiality of a poly(imide) (PI)/organically-modified montmorillonite (O-MMT) nanocomposite membrane for the use in alkaline fuel cells. Both X-ray diffraction and scanning electron microscopy revealed a good dispersion of O-MMT into the PI matrix and preservation of the
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In this work we evaluated the potentiality of a poly(imide) (PI)/organically-modified montmorillonite (O-MMT) nanocomposite membrane for the use in alkaline fuel cells. Both X-ray diffraction and scanning electron microscopy revealed a good dispersion of O-MMT into the PI matrix and preservation of the O-MMT layered structure. When compared to the pure PI, the addition of O-MMT improved thermal stability and markedly increased the capability of absorbing electrolyte and ionic conductivity of the composite. The results show that the PI/O-MMT nanocomposite is a promising candidate for alkaline fuel cell applications. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?
Membranes 2012, 2(3), 478-492; doi:10.3390/membranes2030478
Received: 7 May 2012 / Revised: 21 June 2012 / Accepted: 9 July 2012 / Published: 19 July 2012
Cited by 6 | PDF Full-text (901 KB) | HTML Full-text | XML Full-text
Abstract
Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space
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Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
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Open AccessArticle Proton Content and Nature in Perovskite Ceramic Membranes for Medium Temperature Fuel Cells and Electrolysers
Membranes 2012, 2(3), 493-509; doi:10.3390/membranes2030493
Received: 28 April 2012 / Revised: 8 June 2012 / Accepted: 28 June 2012 / Published: 25 July 2012
Cited by 12 | PDF Full-text (1338 KB) | HTML Full-text | XML Full-text
Abstract
Recent interest in environmentally friendly technology has promoted research on green house gas-free devices such as water steam electrolyzers, fuel cells and CO2/syngas converters. In such applications, proton conducting perovskite ceramics appear especially promising as electrolyte membranes. Prior to a successful
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Recent interest in environmentally friendly technology has promoted research on green house gas-free devices such as water steam electrolyzers, fuel cells and CO2/syngas converters. In such applications, proton conducting perovskite ceramics appear especially promising as electrolyte membranes. Prior to a successful industrial application, it is necessary to determine/understand their complex physical and chemical behavior, especially that related to proton incorporation mechanism, content and nature of bulk protonic species. Based on the results of quasi-elastic neutron scattering (QNS), thermogravimetric analysis (TGA), Raman and IR measurements we will show the complexity of the protonation process and the importance of differentiation between the protonic species adsorbed on a membrane surface and the bulk protons. The bulk proton content is very low, with a doping limit (~1–5 × 10−3 mole/mole), but sufficient to guarantee proton conduction below 600 °C. The bulk protons posses an ionic, covalent bond free nature and may occupy an interstitial site in the host perovskite structure. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle Plasma Membranes Modified by Plasma Treatment or Deposition as Solid Electrolytes for Potential Application in Solid Alkaline Fuel Cells
Membranes 2012, 2(3), 529-552; doi:10.3390/membranes2030529
Received: 25 May 2012 / Revised: 29 June 2012 / Accepted: 11 July 2012 / Published: 30 July 2012
Cited by 7 | PDF Full-text (559 KB) | HTML Full-text | XML Full-text
Abstract
In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology
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In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessArticle Investigation of La1−xSrxCrO3− (x ~ 0.1) as Membrane for Hydrogen Production
Membranes 2012, 2(3), 665-686; doi:10.3390/membranes2030665
Received: 1 August 2012 / Revised: 24 August 2012 / Accepted: 28 August 2012 / Published: 11 September 2012
Cited by 9 | PDF Full-text (898 KB) | HTML Full-text | XML Full-text
Abstract
Various inorganic membranes have demonstrated good capability to separate hydrogen from other gases at elevated temperatures. Hydrogen-permeable, dense, mixed proton-electron conducting ceramic oxides offer superior selectivity and thermal stability, but chemically robust candidates with higher ambipolar protonic and electronic conductivity are needed. In
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Various inorganic membranes have demonstrated good capability to separate hydrogen from other gases at elevated temperatures. Hydrogen-permeable, dense, mixed proton-electron conducting ceramic oxides offer superior selectivity and thermal stability, but chemically robust candidates with higher ambipolar protonic and electronic conductivity are needed. In this work, we present for the first time the results of various investigations of La1−xSrxCrO3− membranes for hydrogen production. We aim in particular to elucidate the material’s complex transport properties, involving co-ionic transport of oxide ions and protons, in addition to electron holes. This opens some new possibilities for efficient heat and mass transfer management in the production of hydrogen. Conductivity measurements as a function of pH2 at constant pO2 exhibit changes that reveal a significant hydration and presence of protons. The flux and production of hydrogen have been measured under different chemical gradients. In particular, the effect of water vapor in the feed and permeate gas stream sides was investigated with the aim of quantifying the ratio of hydrogen production by hydrogen flux from feed to permeate and oxygen flux the opposite way (“water splitting”). Deuterium labeling was used to unambiguously prove flux of hydrogen species. Full article
(This article belongs to the Special Issue Membrane Processes and Energy)

Review

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Open AccessReview Membranes in Lithium Ion Batteries
Membranes 2012, 2(3), 367-383; doi:10.3390/membranes2030367
Received: 30 April 2012 / Revised: 25 June 2012 / Accepted: 27 June 2012 / Published: 4 July 2012
Cited by 34 | PDF Full-text (1735 KB) | HTML Full-text | XML Full-text
Abstract
Lithium ion batteries have proven themselves the main choice of power sources for portable electronics. Besides consumer electronics, lithium ion batteries are also growing in popularity for military, electric vehicle, and aerospace applications. The present review attempts to summarize the knowledge about some
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Lithium ion batteries have proven themselves the main choice of power sources for portable electronics. Besides consumer electronics, lithium ion batteries are also growing in popularity for military, electric vehicle, and aerospace applications. The present review attempts to summarize the knowledge about some selected membranes in lithium ion batteries. Based on the type of electrolyte used, literature concerning ceramic-glass and polymer solid ion conductors, microporous filter type separators and polymer gel based membranes is reviewed. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview A Review of Molecular-Level Mechanism of Membrane Degradation in the Polymer Electrolyte Fuel Cell
Membranes 2012, 2(3), 395-414; doi:10.3390/membranes2030395
Received: 30 April 2012 / Revised: 18 June 2012 / Accepted: 27 June 2012 / Published: 10 July 2012
Cited by 7 | PDF Full-text (751 KB) | HTML Full-text | XML Full-text
Abstract
Chemical degradation of perfluorosulfonic acid (PFSA) membrane is one of the most serious problems for stable and long-term operations of the polymer electrolyte fuel cell (PEFC). The chemical degradation is caused by the chemical reaction between the PFSA membrane and chemical species such
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Chemical degradation of perfluorosulfonic acid (PFSA) membrane is one of the most serious problems for stable and long-term operations of the polymer electrolyte fuel cell (PEFC). The chemical degradation is caused by the chemical reaction between the PFSA membrane and chemical species such as free radicals. Although chemical degradation of the PFSA membrane has been studied by various experimental techniques, the mechanism of chemical degradation relies much on speculations from ex-situ observations. Recent activities applying theoretical methods such as density functional theory, in situ experimental observation, and mechanistic study by using simplified model compound systems have led to gradual clarification of the atomistic details of the chemical degradation mechanism. In this review paper, we summarize recent reports on the chemical degradation mechanism of the PFSA membrane from an atomistic point of view. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview Molecularly Imprinted Membranes
Membranes 2012, 2(3), 440-477; doi:10.3390/membranes2030440
Received: 18 April 2012 / Revised: 20 June 2012 / Accepted: 26 June 2012 / Published: 19 July 2012
Cited by 8 | PDF Full-text (806 KB) | HTML Full-text | XML Full-text
Abstract
Although the roots of molecularly imprinted polymers lie in the beginning of 1930s in the past century, they have had an exponential growth only 40–50 years later by the works of Wulff and especially by Mosbach. More recently, it was also proved that
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Although the roots of molecularly imprinted polymers lie in the beginning of 1930s in the past century, they have had an exponential growth only 40–50 years later by the works of Wulff and especially by Mosbach. More recently, it was also proved that molecular imprinted membranes (i.e., polymer thin films) that show recognition properties at molecular level of the template molecule are used in their formation. Different procedures and potential application in separation processes and catalysis are reported. The influences of different parameters on the discrimination abilities are also discussed. Full article
(This article belongs to the Special Issue Responsive Polymer Membranes)
Open AccessReview Electrochemical Membrane Reactors for Sustainable Chlorine Recycling
Membranes 2012, 2(3), 510-528; doi:10.3390/membranes2030510
Received: 23 May 2012 / Revised: 29 June 2012 / Accepted: 4 July 2012 / Published: 30 July 2012
Cited by 9 | PDF Full-text (1338 KB) | HTML Full-text | XML Full-text
Abstract
Polymer electrolyte membranes have found broad application in a number of processes, being fuel cells, due to energy concerns, the main focus of the scientific community worldwide. Relatively little attention has been paid to the use of these materials in electrochemical production and
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Polymer electrolyte membranes have found broad application in a number of processes, being fuel cells, due to energy concerns, the main focus of the scientific community worldwide. Relatively little attention has been paid to the use of these materials in electrochemical production and separation processes. In this review, we put emphasis upon the application of Nafion membranes in electrochemical membrane reactors for chlorine recycling. The performance of such electrochemical reactors can be influenced by a number of factors including the properties of the membrane, which play an important role in reactor optimization. This review discusses the role of Nafion as a membrane, as well as its importance in the catalyst layer for the formation of the so-called three-phase boundary. The influence of an equilibrated medium on the Nafion proton conductivity and Cl crossover, as well as the influence of the catalyst ink dispersion medium on the Nafion/catalyst self-assembly and its importance for the formation of an ionic conducting network in the catalyst layer are summarized. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)
Open AccessReview Polymer Electrolytes for Lithium/Sulfur Batteries
Membranes 2012, 2(3), 553-564; doi:10.3390/membranes2030553
Received: 9 May 2012 / Revised: 16 July 2012 / Accepted: 17 July 2012 / Published: 9 August 2012
Cited by 28 | PDF Full-text (310 KB) | HTML Full-text | XML Full-text
Abstract
This review evaluates the characteristics and advantages of employing polymer electrolytes in lithium/sulfur (Li/S) batteries. The main highlights of this study constitute detailed information on the advanced developments for solid polymer electrolytes and gel polymer electrolytes, used in the lithium/sulfur battery. This includes
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This review evaluates the characteristics and advantages of employing polymer electrolytes in lithium/sulfur (Li/S) batteries. The main highlights of this study constitute detailed information on the advanced developments for solid polymer electrolytes and gel polymer electrolytes, used in the lithium/sulfur battery. This includes an in-depth analysis conducted on the preparation and electrochemical characteristics of the Li/S batteries based on these polymer electrolytes. Full article
Open AccessReview Microbial Relevant Fouling in Membrane Bioreactors: Influencing Factors, Characterization, and Fouling Control
Membranes 2012, 2(3), 565-584; doi:10.3390/membranes2030565
Received: 20 June 2012 / Revised: 20 July 2012 / Accepted: 9 August 2012 / Published: 15 August 2012
Cited by 11 | PDF Full-text (271 KB) | HTML Full-text | XML Full-text
Abstract
Microorganisms in membrane bioreactors (MBRs) play important roles on degradation of organic/inorganic substances in wastewaters, while microbial deposition/growth and microbial product accumulation on membranes potentially induce membrane fouling. Generally, there is a need to characterize membrane foulants and to determine their relations to
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Microorganisms in membrane bioreactors (MBRs) play important roles on degradation of organic/inorganic substances in wastewaters, while microbial deposition/growth and microbial product accumulation on membranes potentially induce membrane fouling. Generally, there is a need to characterize membrane foulants and to determine their relations to the evolution of membrane fouling in order to identify a suitable fouling control approach in MBRs. This review summarized the factors in MBRs that influence microbial behaviors (community compositions, physical properties, and microbial products). The state-of-the-art techniques to characterize biofoulants in MBRs were reported. The strategies for controlling microbial relevant fouling were discussed and the future studies on membrane fouling mechanisms in MBRs were proposed. Full article
(This article belongs to the Special Issue Membranes in Water Purification)
Open AccessReview A Review of RedOx Cycling of Solid Oxide Fuel Cells Anode
Membranes 2012, 2(3), 585-664; doi:10.3390/membranes2030585
Received: 14 June 2012 / Revised: 16 July 2012 / Accepted: 17 July 2012 / Published: 31 August 2012
Cited by 42 | PDF Full-text (6038 KB) | HTML Full-text | XML Full-text
Abstract
Solid oxide fuel cells are able to convert fuels, including hydrocarbons, to electricity with an unbeatable efficiency even for small systems. One of the main limitations for long-term utilization is the reduction-oxidation cycling (RedOx cycles) of the nickel-based anodes. This paper will review
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Solid oxide fuel cells are able to convert fuels, including hydrocarbons, to electricity with an unbeatable efficiency even for small systems. One of the main limitations for long-term utilization is the reduction-oxidation cycling (RedOx cycles) of the nickel-based anodes. This paper will review the effects and parameters influencing RedOx cycles of the Ni-ceramic anode. Second, solutions for RedOx instability are reviewed in the patent and open scientific literature. The solutions are described from the point of view of the system, stack design, cell design, new materials and microstructure optimization. Finally, a brief synthesis on RedOx cycling of Ni-based anode supports for standard and optimized microstructures is depicted. Full article
(This article belongs to the Special Issue Membranes for Electrochemical Energy Applications)

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