Membranes

16 pages, 12939 KiB

Open AccessArticle

Actin and Microtubules Differently Contribute to Vacuolar Targeting Specificity during the Export from the ER

by Monica De Caroli, Fabrizio Barozzi, Luciana Renna, Gabriella Piro and Gian-Pietro Di Sansebastiano

Membranes 2021, 11(4), 299; https://doi.org/10.3390/membranes11040299 - 20 Apr 2021

Cited by 5 | Viewed by 2848

Abstract

Plants rely on both actin and microtubule cytoskeletons to fine-tune sorting and spatial targeting of membranes during cell growth and stress adaptation. Considerable advances have been made in recent years in the comprehension of the relationship between the trans-Golgi network/early endosome (TGN/EE) and [...] Read more.

Plants rely on both actin and microtubule cytoskeletons to fine-tune sorting and spatial targeting of membranes during cell growth and stress adaptation. Considerable advances have been made in recent years in the comprehension of the relationship between the trans-Golgi network/early endosome (TGN/EE) and cytoskeletons, but studies have mainly focused on the transport to and from the plasma membrane. We address here the relationship of the cytoskeleton with different endoplasmic reticulum (ER) export mechanisms toward vacuoles. These emergent features of the plant endomembrane traffic are explored with an in vivo approach, providing clues on the traffic regulation at different levels beyond known proteins’ functions and interactions. We show how traffic of vacuolar markers, characterized by different vacuolar sorting determinants, diverges at the export from the ER, clearly involving different components of the cytoskeleton. Full article

(This article belongs to the Special Issue Membrane Transport and Cytoskeleton Dynamics)

► Show Figures

Graphical abstract

8 pages, 3386 KiB

Open AccessCommunication

Purification of Wet-Process Phosphoric Acid via Donnan Dialysis with a Perfluorinated Sulfonic Acid Cation-Exchange Membrane

by Qin Zhong, Tao Luo, Zhengjuan Yan, Lin Yang, Zhiye Zhang and Xinlong Wang

Membranes 2021, 11(4), 298; https://doi.org/10.3390/membranes11040298 - 20 Apr 2021

Cited by 6 | Viewed by 2346

Abstract

This work reports the application of an electromembrane process, Donnan dialysis (DD), for the purification of so-called wet-process phosphoric acid (WPA). Nitric acid is used as the stripping solution to remove metallic cations (mostly Fe³⁺, Al³⁺, and Mg²⁺ [...] Read more.

This work reports the application of an electromembrane process, Donnan dialysis (DD), for the purification of so-called wet-process phosphoric acid (WPA). Nitric acid is used as the stripping solution to remove metallic cations (mostly Fe³⁺, Al³⁺, and Mg²⁺) that are harmful to the further processing of WPA. The paper first presents a set of experimental data on the measurements of the metallic cation fluxes through a perfluorinated sulfonic acid cation-exchange membrane. Not only WPA, but also synthetic phosphoric acid solutions with mixed metallic cations (MPA) and with a single metallic cation (SPA) were studied. This confrontation confirms (1) that the order of metallic cations fluxes is Mg²⁺ > Al³⁺ > Fe³⁺; (2) that, compared with MPA, the purification effect of WPA causes only negligible change; (3) that, by comparing the DD processes with SPA and MPA solutions, the reason for the low transmembrane fluxes of Fe³⁺ and Al³⁺ could be explained by the large ionic charge and large hydrated ion radius. Furthermore, by analyzing the ion composition of membranes equilibrated in SPA solutions, we conclude that the forms of cations in the membrane are most likely Fe³⁺, Al³⁺, and Mg²⁺. Full article

(This article belongs to the Special Issue Electromembrane Processes: Emerging Applications, Materials and Process Configurations)

► Show Figures

Figure 1

19 pages, 6110 KiB

Open AccessArticle

Use of Ionic Liquids and Co-Solvents for Synthesis of Thin-Film Composite Membranes

by Peter-Renaat Van den Mooter, Liridona Dedvukaj and Ivo F. J. Vankelecom

Membranes 2021, 11(4), 297; https://doi.org/10.3390/membranes11040297 - 20 Apr 2021

Cited by 4 | Viewed by 2890

Abstract

Polyamide (PA) thin-film composite (TFC) membranes are commonly applied in reversed osmosis (RO) and nanofiltration (NF) applications due to their thin, dense top-layer, and high selectivity. Recently, the conventional organic phase (i.e., hexane) during interfacial polymerization (IP) was replaced by less toxic ionic [...] Read more.

Polyamide (PA) thin-film composite (TFC) membranes are commonly applied in reversed osmosis (RO) and nanofiltration (NF) applications due to their thin, dense top-layer, and high selectivity. Recently, the conventional organic phase (i.e., hexane) during interfacial polymerization (IP) was replaced by less toxic ionic liquids (ILs) which led to excellent membrane performances. As the high price of most ILs limits their up-scaling, the potential use of inexpensive Aliquat was investigated in this study. The thin-film composite (TFC) membranes were optimized to remove flavor compounds, i.e., ethyl acetate (EA) and isoamyl acetate (IA), from a fermentation broth. A multi-parameter optimization was set-up involving type of support, reaction time for IP, water content of Aliquat, and concentration of both monomers m-phenylenediamine (MPD) and trimesoylchloride (TMC). The membranes prepared using Aliquat showed similar fluxes as those prepared from a reference IL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C₄mpyr][Tf₂N]) but with better EA and IA retentions, even better than for a commercial RO membrane (GEA type AF). Finally, the recently introduced epoxide-curing of Bisphenol A diglycidyl ether (BADGE) with 1,6-hexanediamine (HDA) was investigated using Aliquat as organic phase. It is the first time this type of IP was performed in combination with an IL as organic phase. The resulting membrane was used in the filtration of a 35 µM Rose Bengal (RB) in 20 wt% dimethylformamide/ water (DMF/H₂O) feed mixture. A well-crosslinked poly(β-alkanolamine) film was obtained with a > 97% retention. Full article

(This article belongs to the Collection Polymeric Membranes: Science, Materials and Applications)

► Show Figures

Figure 1

21 pages, 4958 KiB

Open AccessArticle

Characteristics of a Plasticized PVA-Based Polymer Electrolyte Membrane and H⁺ Conductor for an Electrical Double-Layer Capacitor: Structural, Morphological, and Ion Transport Properties

by Mohamad A. Brza, Shujahadeen B. Aziz, Hazleen Anuar, Saad M. Alshehri, Fathilah Ali, Tansir Ahamad and Jihad M. Hadi

Membranes 2021, 11(4), 296; https://doi.org/10.3390/membranes11040296 - 20 Apr 2021

Cited by 41 | Viewed by 3183

Abstract

Poly (vinyl alcohol) (PVA)-based solid polymer electrolytes doped with ammonium thiocyanate (NH₄SCN) and glycerol were fabricated using a solution casting method. Lithium-based energy storage devices are not environmentally friendly materials, and they are toxic. Thus, proton-conducting materials were used in this [...] Read more.

Poly (vinyl alcohol) (PVA)-based solid polymer electrolytes doped with ammonium thiocyanate (NH₄SCN) and glycerol were fabricated using a solution casting method. Lithium-based energy storage devices are not environmentally friendly materials, and they are toxic. Thus, proton-conducting materials were used in this work as they are harmless and are smaller than lithium. The interaction between PVA and the electrolyte elements was shown by FTIR analysis. The highest conductivity of 1.82 × 10⁻⁵ S cm⁻¹ was obtained by the highest-conducting plasticized system (PSP_2) at room temperature. The mobility, diffusion coefficient, and number density of anions and cations were found to increase with increasing glycerol. FESEM was used to investigate the influence of glycerol on film morphology. TNM showed that the cations and anions were the main charge carriers. LSV showed that the electrochemical stability window of the PSP_2 system was 1.99 V. The PSP_2 system was applied in the preparation of an electrical double layer capacitor device. The shape of the cyclic voltammetry (CV) curve was nearly rectangular with no Faradaic peaks. From the galvanostatic charge-discharge analysis, the power density, energy density, and specific capacitance values were nearly constant beyond the first cycle at 318.73 W/Kg, 2.06 Wh/Kg, and 18.30 F g⁻¹, respectively, for 450 cycles. Full article

(This article belongs to the Special Issue Membranes in Electrochemistry Applications)

► Show Figures

Figure 1

6 pages, 237 KiB

Open AccessEditorial

Membranes for Water and Wastewater Treatment

by Asunción María Hidalgo and María Dolores Murcia

Membranes 2021, 11(4), 295; https://doi.org/10.3390/membranes11040295 - 19 Apr 2021

Cited by 9 | Viewed by 2181

Abstract

Water is a vital element for life and the environment [...] Full article

(This article belongs to the Special Issue Membranes for Water and Wastewater Treatment)

4 pages, 201 KiB

Open AccessEditorial

Polymeric Membranes

by Vicente Compañ

Membranes 2021, 11(4), 294; https://doi.org/10.3390/membranes11040294 - 19 Apr 2021

Cited by 1 | Viewed by 1751

Abstract

This Special Issue of Polymeric Membranes is dedicated to gathering research carried out within the field of polymeric membranes in different fields of application [...] Full article

(This article belongs to the Special Issue Polymeric Membrane)

15 pages, 2331 KiB

Open AccessArticle

Development of Filter Media by Electrospinning for Air Filtration of Nanoparticles from PET Bottles

by Daniela P. F. Bonfim, Fabiana G. S. Cruz, Vádila G. Guerra and Mônica L. Aguiar

Membranes 2021, 11(4), 293; https://doi.org/10.3390/membranes11040293 - 19 Apr 2021

Cited by 21 | Viewed by 4849

Abstract

Air pollution and solid pollution are considered global problems, and endanger human health mainly due to the emission of fine particulate matter released into the atmosphere and improper disposal of post-consumer plastic bottles. Therefore, it is urgent to develop filter media to effectively [...] Read more.

Air pollution and solid pollution are considered global problems, and endanger human health mainly due to the emission of fine particulate matter released into the atmosphere and improper disposal of post-consumer plastic bottles. Therefore, it is urgent to develop filter media to effectively protect the public. The properties of plastics make them potential candidates for nanofiber mat formers due to their attractive structural and mechanical characteristics. This work aims to produce and evaluate novel PET electrospun fibers dispensed with the use of support materials to be used as filter media to remove nanoparticles from the air. The electrospinning process was carried out by changing the concentration of the polymer solution, the needle diameter, and the electrospinning processing time at two rotation speeds. The average diameters of the micro- and nanofibers of the filter media produced ranged from 3.25 μm to 0.65 μm and it was possible to conclude that, as the size of the fibers decreased, the mechanical strength increased from 3.2 to 4.5 MPa. In filtration tests, a collection efficiency of up to 99% with low-pressure drops (19.4 Pa) was obtained for nanoparticles, demonstrating high quality factor filter media, which could be applicable in gas filtration. Full article

(This article belongs to the Special Issue Nanostructured Membranes II)

► Show Figures

Figure 1

15 pages, 4739 KiB

Open AccessArticle

New Preparation Methods for Pore Formation on Polysulfone Membranes

by Natalia Vainrot, Mingyuan Li, Arun M. Isloor and Moris S. Eisen

Membranes 2021, 11(4), 292; https://doi.org/10.3390/membranes11040292 - 18 Apr 2021

Cited by 7 | Viewed by 3134

Abstract

This work described the preparation of membranes based on aromatic polysulfones through the phase-inversion method induced by a nonsolvent, generating the phase separation (NIPS) process. Three new techniques, including the nano iron acid etching method, base hydrolysis method of crosslinked polymers, and base [...] Read more.

This work described the preparation of membranes based on aromatic polysulfones through the phase-inversion method induced by a nonsolvent, generating the phase separation (NIPS) process. Three new techniques, including the nano iron acid etching method, base hydrolysis method of crosslinked polymers, and base hydrolysis method of a reactive component in a binary polymer blend, were developed for pore creation on membranes. The modified polymers and obtained membranes were carefully characterized. The uniform pores were successfully created by base hydrolysis of the crosslinked polymers and obtained at the size of the crosslinker. Moreover, homogeneous pores were created after base hydrolysis of the membranes prepared from binary polymer blends due to the internal changes in the polymer structure. The separation performance of membranes was tested with different inorganic salt solutions and compared with commercially known membranes. These new membranes exhibited high water flux (up to 3000 L/m⁻²·h⁻¹ at 10 bar and at 25 °C) and reasonable rejections for monovalent (21–44%) and multivalent ions (18–60%), depending on the different etching of the hydrolysis times. The comparison of these membranes with commercial ones confirmed their good separation performance and high potential application for water treatment applications. Full article

(This article belongs to the Special Issue Membrane Processes for Environmental Applications)

► Show Figures

Graphical abstract

9 pages, 1027 KiB

Open AccessArticle

Separation of Boron from Geothermal Waters with Membrane System

by Kadir Seval, Canan Onac, Ahmet Kaya and Abdullah Akdogan

Membranes 2021, 11(4), 291; https://doi.org/10.3390/membranes11040291 - 16 Apr 2021

Cited by 3 | Viewed by 2052

Abstract

This study presents the separation and recovery of boron from geothermal waters with a polymeric membrane system and suggests a transport mechanism. The optimum relative parameters of the transport were examined. The recovery value of boron was 60.46% by using polymeric membrane system [...] Read more.

This study presents the separation and recovery of boron from geothermal waters with a polymeric membrane system and suggests a transport mechanism. The optimum relative parameters of the transport were examined. The recovery value of boron was 60.46% by using polymeric membrane system from prepared aquatic solution to the acceptor phase. The membrane’s capacity and selectivity of the transport process were examined. Kinetics values were calculated for each transport parameter. The optimum kinetic values were 1.4785 × 10⁻⁶ (s⁻¹), 7.3273 × 10⁻⁸ (m/s), 13.5691 × 10⁻⁸ (mol/m².s), 5.8174 × 10⁻¹² (m²/s) for constant rate, permeability coefficient, flux, and diffusion coefficient, respectively. Boron was transported selectively and successfully from geothermal waters in the presence of other metal cations with 59.85% recovery value. This study indicates the application of real samples in polymeric membrane systems, which are very practical, economic, and easy to use for large-scale applications. The chemical and physical properties of polymer inclusion membranes (PIMs) offer the opportunity to be specially designed for specific applications. Full article

(This article belongs to the Special Issue Polymer Membranes in Separation Process)

► Show Figures

Figure 1

15 pages, 6232 KiB

Open AccessArticle

Influence of Deposition Parameters of TiO₂ + CuO Coating on the Membranes Surface Used in the Filtration Process of Dairy Wastewater on Their Functional Properties

by Joanna Kacprzyńska-Gołacka, Monika Łożyńska, Wioletta Barszcz, Sylwia Sowa, Piotr Wieciński, Ewa Woskowicz and Maciej Życki

Membranes 2021, 11(4), 290; https://doi.org/10.3390/membranes11040290 - 16 Apr 2021

Cited by 5 | Viewed by 2176

Abstract

A novel approach of the deposition of two-component coating consisting of TiO₂ and CuO on polymer membranes by MS-PVD method was presented in this work. This confirmed the possibility of using thin functional coatings for the modification of polymer membranes. The influence [...] Read more.

A novel approach of the deposition of two-component coating consisting of TiO₂ and CuO on polymer membranes by MS-PVD method was presented in this work. This confirmed the possibility of using thin functional coatings for the modification of polymer membranes. The influence of technological parameters of the coating deposition on the membrane’s structure, chemical composition and functional properties (hydrophilic, photocatalytic and bactericidal properties) were analyzed using SEM. Model microorganism such as Escherichia coli and Bacillus subtilis have been used to check the antibacterial properties. The results indicated that doping with CuO highlights the potential of bactericidal efficiency. The surface properties of the membranes were evaluated with the surface free energy. For evaluating photocatalytic properties, the UV and visible light were used. The filtration tests showed that polymer membranes treated with two-component TiO₂ + CuO coatings have a permeate flux similar to the reference material (non-coated membrane). The obtained results constitute a very promising perspective of the potential application of magnetron sputtering for deposition of TiO₂ + CuO coatings in the prevention of biofouling resulted from the membrane filtration of dairy wastewater. Full article

(This article belongs to the Collection New Challenges in Membranes for Water and Wastewater Application)

► Show Figures

Graphical abstract

20 pages, 3156 KiB

Open AccessArticle

Improving EDLC Device Performance Constructed from Plasticized Magnesium Ion Conducting Chitosan Based Polymer Electrolytes via Metal Complex Dispersion

by Shujahadeen B. Aziz, Elham M. A. Dannoun, M. H. Hamsan, Rebar T. Abdulwahid, Kuldeep Mishra, Muaffaq M. Nofal and M. F. Z. Kadir

Membranes 2021, 11(4), 289; https://doi.org/10.3390/membranes11040289 - 14 Apr 2021

Cited by 26 | Viewed by 2903

Abstract

The current work shows the preparation of plasticized chitosan-magnesium acetate Mg(CH₃COO)₂-based polymer electrolyte dispersed with nickel (Ni) metal complexes via solution casting. Investigations of electrical and electrochemical properties of the prepared polymer composite electrolyte were carried out. The structural [...] Read more.

The current work shows the preparation of plasticized chitosan-magnesium acetate Mg(CH₃COO)₂-based polymer electrolyte dispersed with nickel (Ni) metal complexes via solution casting. Investigations of electrical and electrochemical properties of the prepared polymer composite electrolyte were carried out. The structural and optical properties of the samples were studied using X-ray diffraction (XRD) and UV-Vis spectroscopy techniques. The structural and optical outcomes revealed a clear enhancement in both absorbance and amorphous nature of the samples upon the addition of Ni metal complexes. Through the simulation of impedance data, various ion transport parameters were calculated. The electrochemical performance of the sample was examined by means of transference number measurement (TNM), linear sweep voltammetry (LSV) and cyclic voltammetry (CV) measurements. The TNM analysis confirmed the dominance of ions as the main charge carrier in the electrolyte with t_ion of (0.96) compared to only (0.04) for t_el. The present electrolyte was stable in the range of 0 V to 2.4 V, which was obtained from linear sweep voltammetry (LSV). A result from CV proved that the electrical double-layer capacitor (EDLC) has a capacitive behavior as no redox peaks could be observed. The presence of Ni improved the charge–discharge cycle of the EDLC due to its amorphous behavior. The average performances of the EDLC were recorded as 41.7 F/g, 95%, 5.86 Wh/kg and 628 W/kg for specific capacitance, coulombic efficiency, energy and power densities, respectively. The fabricated EDLC device was found to be stable up to 1000 cycles. Full article

(This article belongs to the Special Issue Polymer Membranes and beyond for Sustainable Separations: From Synthesis, Characterization to Applications)

► Show Figures

Figure 1

18 pages, 7760 KiB

Open AccessArticle

Integration of Response Surface Methodology (RSM) and Principal Component Analysis (PCA) as an Optimization Tool for Polymer Inclusion Membrane Based-Optodes Designed for Hg(II), Cd(II), and Pb(II)

by Jeniffer García-Beleño and Eduardo Rodríguez de San Miguel

Membranes 2021, 11(4), 288; https://doi.org/10.3390/membranes11040288 - 14 Apr 2021

Cited by 7 | Viewed by 2409

Abstract

An optimization of the composition of polymer inclusion membrane (PIM)-based optodes, and their exposure times to metal ion solutions (Hg(II), Cd(II), and Pb(II)) was performed using two different chromophores, diphenylthiocarbazone (dithizone) and 1-(2-pyridylazo)-2-naphthol (PAN). Four factors were evaluated (chromophore (0.06–1 mg), cellulose triacetate [...] Read more.

An optimization of the composition of polymer inclusion membrane (PIM)-based optodes, and their exposure times to metal ion solutions (Hg(II), Cd(II), and Pb(II)) was performed using two different chromophores, diphenylthiocarbazone (dithizone) and 1-(2-pyridylazo)-2-naphthol (PAN). Four factors were evaluated (chromophore (0.06–1 mg), cellulose triacetate (25–100 mg) and plasticizer amounts (25–100 mg), and exposure time (20–80 min)). Derringer’s desirability functions values were employed as response variables to perform the optimization obtained from the results of three different processes of spectral data treatment: two full-spectrum methods (M1 and M3) and one band-based method (M2). The three different methods were compared using a heatmap of the coefficients and dendrograms of the Principal Component Analysis (PCA)reductions of their desirability functions. The final recommended M3 processing method, i.e., using the scores values of the first two principal components in PCA after subtraction of the normalized spectra of the membranes before and after complexation, gave more discernable differences between the PIMs in the Design of Experiments (DoE), as the nodes among samples appeared at longer distances and varyingly distributed in the dendrogram analysis. The optimal values were time of 35–65 min, 0.53 mg–1.0 mg of chromophores, plasticizers 34.4–71.9 of chromophores, and 62.5–100 mg of CTA, depending on the metal ion. In addition, the method yielded the best outcomes in terms of interpretability and an easily discernable color change so that it is recommended as a novel optimization method for this kind of PIM optode. Full article

(This article belongs to the Special Issue Polymer Inclusion Membranes)

► Show Figures

Figure 1

12 pages, 3534 KiB

Open AccessArticle

Extending the Anion Channelrhodopsin-Based Toolbox for Plant Optogenetics

by Yang Zhou, Meiqi Ding, Xiaodong Duan, Kai R. Konrad, Georg Nagel and Shiqiang Gao

Membranes 2021, 11(4), 287; https://doi.org/10.3390/membranes11040287 - 14 Apr 2021

Cited by 9 | Viewed by 2875

Abstract

Optogenetics was developed in the field of neuroscience and is most commonly using light-sensitive rhodopsins to control the neural activities. Lately, we have expanded this technique into plant science by co-expression of a chloroplast-targeted β-carotene dioxygenase and an improved anion channelrhodopsin GtACR1 [...] Read more.

Optogenetics was developed in the field of neuroscience and is most commonly using light-sensitive rhodopsins to control the neural activities. Lately, we have expanded this technique into plant science by co-expression of a chloroplast-targeted β-carotene dioxygenase and an improved anion channelrhodopsin GtACR1 from the green alga Guillardia theta. The growth of Nicotiana tabacum pollen tube can then be manipulated by localized green light illumination. To extend the application of analogous optogenetic tools in the pollen tube system, we engineered another two ACRs, GtACR2, and ZipACR, which have different action spectra, light sensitivity and kinetic features, and characterized them in Xenopus laevis oocytes, Nicotiana benthamiana leaves and N. tabacum pollen tubes. We found that the similar molecular engineering method used to improve GtACR1 also enhanced GtACR2 and ZipACR performance in Xenopus laevis oocytes. The ZipACR1 performed in N. benthamiana mesophyll cells and N. tabacum pollen tubes with faster kinetics and reduced light sensitivity, allowing for optogenetic control of anion fluxes with better temporal resolution. The reduced light sensitivity would potentially facilitate future application in plants, grown under low ambient white light, combined with an optogenetic manipulation triggered by stronger green light. Full article

(This article belongs to the Special Issue Membrane Channel of Cells)

► Show Figures

Figure 1

12 pages, 1964 KiB

Open AccessArticle

Influence of Casting Solvents on CO₂/CH₄ Separation Using Polysulfone Membranes

by Roba M. Almuhtaseb, Ahmed Awadallah-F, Shaheen A. Al-Muhtaseb and Majeda Khraisheh

Membranes 2021, 11(4), 286; https://doi.org/10.3390/membranes11040286 - 13 Apr 2021

Cited by 6 | Viewed by 2411

Abstract

Polysulfone membranes exhibit resistance to high temperature with low manufacturing cost and high efficiency in the separation process. The composition of gases is an important step that estimates the efficiency of separation in membranes. As membrane types are currently becoming in demand for [...] Read more.

Polysulfone membranes exhibit resistance to high temperature with low manufacturing cost and high efficiency in the separation process. The composition of gases is an important step that estimates the efficiency of separation in membranes. As membrane types are currently becoming in demand for CO₂/CH₄ segregation, polysulfone will be an advantageous alternative to have in further studies. Therefore, research is undertaken in this study to evaluate two solvents: chloroform (CF) and tetrahydrofuran (THF). These solvents are tested for casting polymeric membranes from polysulfone (PSF) to separate every single component from a binary gas mixture of CO₂/CH₄. In addition, the effect of gas pressure was conducted from 1 to 10 bar on the behavior of the permeability and selectivity. The results refer to the fact that the maximum permeability of CO₂ and CH₄ for THF is 62.32 and 2.06 barrer at 1 and 2 bars, respectively. Further, the maximum permeability of CF is 57.59 and 2.12 barrer at 1 and 2 bars, respectively. The outcome selectivity values are 48 and 36 for THF and CF at 1 bar, accordingly. Furthermore, the study declares that with the increase in pressure, the permeability and selectivity values drop for CF and THF. The performance for polysulfone (PSF) membrane that is manufactured with THF is superior to that of CF relative to the Robeson upper bound. Therefore, through the results, it can be deduced that the solvent during in-situ synthesis has a significant influence on the gas separation of a binary mixture of CO₂/CH₄. Full article

(This article belongs to the Section Polymeric Membranes)

► Show Figures

Figure 1

19 pages, 19670 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Calixresorcin[4]arene-Mediated Transport of Pb(II) Ions through Polymer Inclusion Membrane

by Joanna Konczyk and Wojciech Ciesielski

Membranes 2021, 11(4), 285; https://doi.org/10.3390/membranes11040285 - 13 Apr 2021

Cited by 8 | Viewed by 2138

Abstract

A facilitated transport of Pb(II) through polymer inclusion membrane (PIM) containing 1,8,15,22-tetra(1-heptyl)-calixresorcin[4]arene and its tetra- and octasubstituted derivatives containing phosphoryl, thiophosphoryl or ester groups as an ion carrier was investigated. The efficiency of Pb(II) removal from aqueous nitrate solutions was considered as a [...] Read more.

A facilitated transport of Pb(II) through polymer inclusion membrane (PIM) containing 1,8,15,22-tetra(1-heptyl)-calixresorcin[4]arene and its tetra- and octasubstituted derivatives containing phosphoryl, thiophosphoryl or ester groups as an ion carrier was investigated. The efficiency of Pb(II) removal from aqueous nitrate solutions was considered as a function of the composition of membrane (effect of polymer, plasticizer, and carrier), feed (effect of initial metal concentration and presence of other metal ions) and stripping phases, and temperature of the process conducting. Two kinetic models were applied for the transport description. The highest Pb(II) ions removal efficiency was obtained for the membrane with tetrathiophosphorylated heptyl-calixresorcin[4]arene as an ion carrier. The activation energy value, found from Eyring plot to be equal 38.7 ± 1.3 kJ/mol, suggests that the transport process is controllable both by diffusion and chemical reaction. The competitive transport of Pb(II) over Zn(II), Cd(II), and Cr(III) ions across PIMs under the optimal conditions was also performed. It was found that the Cr(III) ions’ presence in the feed phase disturb effective re-extraction of Pb(II) ions from membrane to stripping phase. Better stability of PIM-type than SLM-type membrane was found. Full article

(This article belongs to the Special Issue Polymer Membranes in Separation Process)

► Show Figures

Graphical abstract

13 pages, 42198 KiB

Open AccessArticle

Carbon Molecular Sieve Membranes Comprising Graphene Oxides and Porous Carbon for CO₂/N₂ Separation

by Chong Yang Chuah, Junghyun Lee, Juha Song and Tae-Hyun Bae

Membranes 2021, 11(4), 284; https://doi.org/10.3390/membranes11040284 - 12 Apr 2021

Cited by 15 | Viewed by 4081

Abstract

To improve the CO₂/N₂ separation performance, mixed-matrix carbon molecular sieve membranes (mixed-matrix CMSMs) were fabricated and tested. Two carbon-based fillers, graphene oxide (GO) and activated carbon (YP-50F), were separately incorporated into two polymer precursors (Matrimid^® 5218 and ODPA-TMPDA), and [...] Read more.

To improve the CO₂/N₂ separation performance, mixed-matrix carbon molecular sieve membranes (mixed-matrix CMSMs) were fabricated and tested. Two carbon-based fillers, graphene oxide (GO) and activated carbon (YP-50F), were separately incorporated into two polymer precursors (Matrimid^® 5218 and ODPA-TMPDA), and the resulting CMSMs demonstrated improved CO₂ permeability. The improvement afforded by YP-50F was more substantial due to its higher accessible surface area. Based on the gas permeation data and the Robeson plot for CO₂/N₂ separation, the performances of the CMSMs containing 15 wt % YP-50F and 15 wt % GO in the mixed polymer matrix surpassed the 2008 Robeson upper bound of polymeric membranes. Hence, this study demonstrates the feasibility of such membranes in improving the CO₂/N₂ separation performance through the appropriate choice of carbon-based filler materials in polymer matrices. Full article

(This article belongs to the Special Issue Emerging Materials for Mixed-Matrix Membranes)

► Show Figures

Graphical abstract

11 pages, 3814 KiB

Open AccessArticle

Diabetic Pathophysiology Enhances Inflammation during Extracorporeal Membrane Oxygenation in a Rat Model

by Yutaka Fujii, Takuya Abe and Kikuo Ikegami

Membranes 2021, 11(4), 283; https://doi.org/10.3390/membranes11040283 - 11 Apr 2021

Cited by 7 | Viewed by 2822

Abstract

Systemic inflammatory responses in patients undergoing extracorporeal membrane oxygenation (ECMO) contribute significantly to ECMO-associated morbidity and mortality. In recent years, the number of type 2 diabetes mellitus patients has increased, and the number of these patients undergoing ECMO has also increased. Type 2 [...] Read more.

Systemic inflammatory responses in patients undergoing extracorporeal membrane oxygenation (ECMO) contribute significantly to ECMO-associated morbidity and mortality. In recent years, the number of type 2 diabetes mellitus patients has increased, and the number of these patients undergoing ECMO has also increased. Type 2 diabetes mellitus is a high-risk factor for complications during ECMO. We studied the effects of ECMO on inflammatory response in a diabetic rat ECMO model. Twenty-eight rats were divided into 4 groups: normal SHAM group (normal rats: n = 7), diabetic SHAM group (diabetic rats: n = 7), normal ECMO group (normal rats: n = 7), and diabetic ECMO group (diabetic rats: n = 7). We measured the plasma levels of cytokines, tumor necrosis factor-α, and interleukin-6. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), blood urea nitrogen (BUN), creatinine (Cr), and liver-type fatty acid binding protein (L-FABP) were examined in the rat cardiopulmonary bypass model to ascertain organ damage. In addition, the lung wet-to-dry weight (W/D) ratio was measured as an index of pulmonary tissue edema. A pathologic evaluation of kidneys was conducted by hematoxylin-eosin (HE) and periodic-acid-methenamine-silver (PAM) staining. In the diabetic ECMO group, levels of cytokines, AST, ALT, LDH, and L-FABP increased significantly, reaching a maximum at the end of ECMO in comparison with other groups (p < 0.05). In addition, hematoxylin-eosin and periodic acid-methenamine-silver staining of renal tissues showed marked injury in the ECMO group (normal ECMO and diabetic ECMO groups). Furthermore, when the normal ECMO and diabetic ECMO groups were compared, severe organ injury was seen in the diabetic ECMO group. There was remarkable organ injury in the diabetic ECMO group. These data demonstrate that diabetes enhances proinflammatory cytokine release, renal damage, and pulmonary edema during ECMO in an animal model. Full article

(This article belongs to the Special Issue Advances in Extracorporeal Membrane Oxygenation)

► Show Figures

Figure 1

24 pages, 11703 KiB

Open AccessArticle

Hydrogen Separation and Purification from Various Gas Mixtures by Means of Electrochemical Membrane Technology in the Temperature Range 100–160 °C

by Leandri Vermaak, Hein W. J. P. Neomagus and Dmitri G. Bessarabov

Membranes 2021, 11(4), 282; https://doi.org/10.3390/membranes11040282 - 10 Apr 2021

Cited by 31 | Viewed by 8450

Abstract

This paper reports on an experimental evaluation of the hydrogen separation performance in a proton exchange membrane system with Pt-Co/C as the anode electrocatalyst. The recovery of hydrogen from H₂/CO₂, H₂/CH₄, and H₂/NH [...] Read more.

This paper reports on an experimental evaluation of the hydrogen separation performance in a proton exchange membrane system with Pt-Co/C as the anode electrocatalyst. The recovery of hydrogen from H₂/CO₂, H₂/CH₄, and H₂/NH₃ gas mixtures were determined in the temperature range of 100–160 °C. The effects of both the impurity concentration and cell temperature on the separation performance of the cell and membrane were further examined. The electrochemical properties and performance of the cell were determined by means of polarization curves, limiting current density, open-circuit voltage, hydrogen permeability, hydrogen selectivity, hydrogen purity, and cell efficiencies (current, voltage, and power efficiencies) as performance parameters. High purity hydrogen (>99.9%) was obtained from a low purity feed (20% H₂) after hydrogen was separated from H₂/CH₄ mixtures. Hydrogen purities of 98–99.5% and 96–99.5% were achieved for 10% and 50% CO₂ in the feed, respectively. Moreover, the use of proton exchange membranes for electrochemical hydrogen separation was unsuccessful in separating hydrogen-rich streams containing NH₃; the membrane underwent irreversible damage. Full article

(This article belongs to the Special Issue Electrically Conductive Membranes)

► Show Figures

Figure 1

11 pages, 6100 KiB

Open AccessArticle

Mass Transfer Analysis of Air-Cooled Membrane Distillation Configuration for Desalination

by Shuo Cong, Qingxiu Miao and Fei Guo

Membranes 2021, 11(4), 281; https://doi.org/10.3390/membranes11040281 - 10 Apr 2021

Cited by 3 | Viewed by 2456

Abstract

It has been proposed that the air-cooled configuration for air gap membrane distillation is an effective way to simplify the system design and energy source requirement. This offers potential for the practical applications of membrane distillation on an industrial scale. In this work, [...] Read more.

It has been proposed that the air-cooled configuration for air gap membrane distillation is an effective way to simplify the system design and energy source requirement. This offers potential for the practical applications of membrane distillation on an industrial scale. In this work, membrane distillation tests were performed using a typical water-cooled membrane distillation (WCMD) configuration and an air-cooled membrane distillation (ACMD) configuration with various condensing plates and operating conditions. To increase the permeate flux of an ACMD system, the condensing plate in the permeate side should transfer heat to the atmosphere more effectively, such as using a more thermally conductive plate, adding fins, or introducing forced convection air flow. Importantly, a practical mass transfer model was proposed to describe the ACMD performance in terms of permeate flux. This model can be simplified by introducing specific correction values to the mass transfer coefficient of a WCMD process under the same conditions. The two factors relate to the capacity (B) and the efficiency (σ), which can be considered as the characteristic factors of a membrane distillation (MD) system. The experimental results are consistent with the theoretical estimations based on this model, which can be used to describe the performance of an MD process. Full article

(This article belongs to the Special Issue Recent Advances in Membrane Distillation)

► Show Figures

Figure 1

18 pages, 5236 KiB

Open AccessArticle

Hybrid Ceramic Membranes for the Removal of Pharmaceuticals from Aqueous Solutions

by Jenny Radeva, Anke Gundula Roth, Christian Göbbert, Robert Niestroj-Pahl, Lars Dähne, Axel Wolfram and Jürgen Wiese

Membranes 2021, 11(4), 280; https://doi.org/10.3390/membranes11040280 - 10 Apr 2021

Cited by 9 | Viewed by 3259

Abstract

Layer-by-Layer (LbL) technology was used to coat alumina ceramic membranes with nanosized polyelectrolyte films. The polyelectrolyte chains form a network with nanopores on the ceramic surface and promote the rejection of small molecules such as pharmaceuticals, salts and industrial contaminants, which can otherwise [...] Read more.

Layer-by-Layer (LbL) technology was used to coat alumina ceramic membranes with nanosized polyelectrolyte films. The polyelectrolyte chains form a network with nanopores on the ceramic surface and promote the rejection of small molecules such as pharmaceuticals, salts and industrial contaminants, which can otherwise not be eliminated using standard ultrafiltration methods. The properties and performance of newly developed hybrid membranes are in the focus of this investigation. The homogeneity of the applied coating layer was investigated by confocal fluorescence microscopy and scanning transmission electron microscopy (STEM). Properties such as permeability, bubble point, pore size distribution and Zeta potential were determined for both pristine and LbL coated membranes using various laboratory tests. Subsequently, a thorough comparison was drawn. The charging behavior at solid-liquid interface was characterized using streaming potential techniques. The retention potential was monitored by subjecting widely used pharmaceuticals such as diclofenac, ibuprofen and sulfamethoxazol. The results prove a successful elimination of pharmaceutical contaminants, up to 84% from drinking water, by applying a combination of polyelectrolyte multilayers and ceramic membranes. Full article

(This article belongs to the Special Issue Enhancing the Efficiency of Membrane Processes for Water Treatment)

► Show Figures

Figure 1

20 pages, 11450 KiB

Open AccessReview

Enantioselective Mixed Matrix Membranes for Chiral Resolution

by Hwa-Jin Choi, Yun-Ho Ahn and Dong-Yeun Koh

Membranes 2021, 11(4), 279; https://doi.org/10.3390/membranes11040279 - 10 Apr 2021

Cited by 21 | Viewed by 5255

Abstract

Most pharmaceuticals are stereoisomers that each enantiomer shows dramatically different biological activity. Therefore, the production of optically pure chemicals through sustainable and energy-efficient technology is one of the main objectives in the pharmaceutical industry. Membrane-based separation is a continuous process performed on a [...] Read more.

Most pharmaceuticals are stereoisomers that each enantiomer shows dramatically different biological activity. Therefore, the production of optically pure chemicals through sustainable and energy-efficient technology is one of the main objectives in the pharmaceutical industry. Membrane-based separation is a continuous process performed on a large scale that uses far less energy than the conventional thermal separation process. Enantioselective polymer membranes have been developed for chiral resolution of pharmaceuticals; however, it is difficult to generate sufficient enantiomeric excess (ee) with conventional polymers. This article describes a chiral resolution strategy using a composite structure of mixed matrix membrane that employs chiral fillers. We discuss several enantioselective fillers, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), zeolites, porous organic cages (POCs), and their potential use as chiral fillers in mixed matrix membranes. State-of-the-art enantioselective mixed matrix membranes (MMMs) and the future design consideration for highly efficient enantioselective MMMs are discussed. Full article

(This article belongs to the Special Issue Emerging Materials for Mixed-Matrix Membranes)

► Show Figures

Figure 1

15 pages, 1617 KiB

Open AccessArticle

Concentration of Municipal MBBR Effluent by FO for Resource Recovery: Batch Experiments in Side-Stream Configuration

by Willy Røstum Thelin, Edvard Sivertsen, Gema Raspati, Kamal Azrague and Herman Helness

Membranes 2021, 11(4), 278; https://doi.org/10.3390/membranes11040278 - 10 Apr 2021

Cited by 3 | Viewed by 1775

Abstract

A novel approach for resource recovery includes forward osmosis (FO) as a concentration step in municipal wastewater treatment. The current study investigates different pre-treatment strategies including biological treatment with a moving-bed bioreactor (MBBR) at different loading rates and particle removal by filtration and [...] Read more.

A novel approach for resource recovery includes forward osmosis (FO) as a concentration step in municipal wastewater treatment. The current study investigates different pre-treatment strategies including biological treatment with a moving-bed bioreactor (MBBR) at different loading rates and particle removal by filtration and sedimentation. Membrane performance and recovery potential for energy and nutrients were investigated in laboratory-scale FO experiments in batch mode using pre-treated municipal wastewater as feed and 35 g/L NaCl as a draw solution. Initial water fluxes were in the range of 6.3 to 8.0 L/(m²·h). The baseline fluxes were modelled to account for flux decline due to concentration effects and to enable the prediction of flux decline due to membrane fouling. Fouling-related flux decline varied from 0 to 31%. Both organic fouling and precipitation of CaCO₃ and CaHPO₄ were identified by using SEM–EDS. High-rate flushing resulted in complete flux recovery under most conditions. Scaling could be avoided by lowering the pH. Two operation strategies were tested to achieve this: (1) applying a bioreactor with a low organic loading rate to achieve high nitrification, and (2) adding a strong acid. A low organic loading rate and the use of additional particle removal were efficient measures that reduced organic/particulate fouling. The recovery potentials for COD and phosphorous in FO concentrate were close to 100%. Full article

(This article belongs to the Special Issue Recent Advances in Membrane Materials and Membrane Processes for Water and Wastewater Treatment)

► Show Figures

Figure 1

31 pages, 16070 KiB

Open AccessReview

Ion Transport in Solid Medium—Evaluation of Ionic Mobility for Design of Ion Transport Pathways in Separator and Gel Electrolyte

by Yuria Saito

Membranes 2021, 11(4), 277; https://doi.org/10.3390/membranes11040277 - 09 Apr 2021

Cited by 10 | Viewed by 2671

Abstract

Further improvement in the performance of lithium secondary batteries will be an indispensable issue to realize a decarbonized society. Among them, the batteries for electric vehicles still have many issues to be addressed because they are subject to various conditions such as high-power [...] Read more.

Further improvement in the performance of lithium secondary batteries will be an indispensable issue to realize a decarbonized society. Among them, the batteries for electric vehicles still have many issues to be addressed because they are subject to various conditions such as high-power performance, safety, and cost restrictions for widespread use. Those subjects require extensive researches from the improvement of each element material to control the battery system to optimize the total performance. Based on this idea, we have been conducting research focusing on ion movement to elucidate the ion conduction mechanism from the microscopic point of view. It has been recognized that the ionic mobility in the battery, which dominates the power performance of the battery, is affected by the solid environment in which the ions move (separator and electrode materials) and the evaluation of ion movement, including the interaction with the surroundings, is necessary as an essential step for battery design. In this article, I will introduce the evaluation approach of ion dynamics and the evaluation results of mobility and interactive situations of carrier ions in the practical separator membranes and gel electrolytes. Finally, the direction of material design is outlined through this review. Full article

(This article belongs to the Special Issue Separator Membrane in Lithium Batteries)

► Show Figures

Figure 1

13 pages, 5779 KiB

Open AccessArticle

Flexible 5-in-1 Microsensor Embedded in the Proton Battery for Real-Time Microscopic Diagnosis

by Chi-Yuan Lee, Chia-Hung Chen, John-Shong Cheong, Yun-Hsiu Chien and Yi-Chuan Lin

Membranes 2021, 11(4), 276; https://doi.org/10.3390/membranes11040276 - 08 Apr 2021

Cited by 5 | Viewed by 1758

Abstract

The proton battery possesses water electrolysis, proton storage and discharging functions simultaneously, and it can be manufactured without expensive metals. Use the principle of proton exchange membrane water electrolysis for charging, store it in the activated carbon on the hydrogen side and use [...] Read more.

The proton battery possesses water electrolysis, proton storage and discharging functions simultaneously, and it can be manufactured without expensive metals. Use the principle of proton exchange membrane water electrolysis for charging, store it in the activated carbon on the hydrogen side and use the principle of proton exchange membrane fuel cell for discharge when needed. According to the latest literature, it is difficult to obtain the exact important physical parameters inside the proton battery (e.g., voltage, current, temperature, humidity and flow), and the important physical parameters are correlated with each other, which have critical influence on the performance, lifetime and health status of the proton battery. At present, the condition of the proton battery is judged indirectly only by external measurement, the actual situation inside the proton battery cannot be obtained accurately and instantly. Therefore, this study uses micro-electro-mechanical systems (MEMS) technology to develop a flexible 5-in-1 microsensor, which is embedded in the proton battery to obtain five important physical parameters instantly, so that the condition inside the proton battery can be mastered more precisely, so as to prolong the battery life and enhance the proton battery performance. Full article

(This article belongs to the Special Issue Membranes for Energy Conversion)

► Show Figures

Figure 1

16 pages, 10154 KiB

Open AccessEditor’s ChoiceReview

S-Layer Ultrafiltration Membranes

by Bernhard Schuster and Uwe B. Sleytr

Membranes 2021, 11(4), 275; https://doi.org/10.3390/membranes11040275 - 08 Apr 2021

Cited by 11 | Viewed by 3134

Abstract

Monomolecular arrays of protein subunits forming surface layers (S-layers) are the most common outermost cell envelope components of prokaryotic organisms (bacteria and archaea). Since S-layers are periodic structures, they exhibit identical physicochemical properties for each constituent molecular unit down to the sub-nanometer level. [...] Read more.

Monomolecular arrays of protein subunits forming surface layers (S-layers) are the most common outermost cell envelope components of prokaryotic organisms (bacteria and archaea). Since S-layers are periodic structures, they exhibit identical physicochemical properties for each constituent molecular unit down to the sub-nanometer level. Pores passing through S-layers show identical size and morphology and are in the range of ultrafiltration membranes. The functional groups on the surface and in the pores of the S-layer protein lattice are accessible for chemical modifications and for binding functional molecules in very precise fashion. S-layer ultrafiltration membranes (SUMs) can be produced by depositing S-layer fragments as a coherent (multi)layer on microfiltration membranes. After inter- and intramolecular crosslinking of the composite structure, the chemical and thermal resistance of these membranes was shown to be comparable to polyamide membranes. Chemical modification and/or specific binding of differently sized molecules allow the tuning of the surface properties and molecular sieving characteristics of SUMs. SUMs can be utilized as matrices for the controlled immobilization of functional biomolecules (e.g., ligands, enzymes, antibodies, and antigens) as required for many applications (e.g., biosensors, diagnostics, enzyme- and affinity-membranes). Finally, SUM represent unique supporting structures for stabilizing functional lipid membranes at meso- and macroscopic scale. Full article

(This article belongs to the Special Issue Biological and Biomimetic Membranes: New Materials and Emerging Processes 2021)

► Show Figures

Graphical abstract

16 pages, 2893 KiB

Open AccessArticle

Polyimide-Based Membrane Materials for CO₂ Separation: A Comparison of Segmented and Aromatic (Co)polyimides

by Andrzej Jankowski, Eugenia Grabiec, Klaudia Nocoń-Szmajda, Andrzej Marcinkowski, Henryk Janeczek and Aleksandra Wolińska-Grabczyk

Membranes 2021, 11(4), 274; https://doi.org/10.3390/membranes11040274 - 08 Apr 2021

Cited by 20 | Viewed by 3530

Abstract

A series of new poly(ethylene oxide) (PEO)-based copolyimides varying in hard segment structure are reported in this work as CO₂ selective separation membranes. Their structural diversity was achieved by using different aromatic dianhydrides (4,4′-oxydiphthalic anhydride (ODPA), 4,4’-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)) and diamines (4,4′-oxydianiline [...] Read more.

A series of new poly(ethylene oxide) (PEO)-based copolyimides varying in hard segment structure are reported in this work as CO₂ selective separation membranes. Their structural diversity was achieved by using different aromatic dianhydrides (4,4′-oxydiphthalic anhydride (ODPA), 4,4’-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)) and diamines (4,4′-oxydianiline (ODA), 4,4′-(4,4′-isopropylidene-diphenyl-1,1′- diyldioxy)dianiline (IPrDA), 2,3,5,6-tetramethyl-1,4-phenylenediamine (4MPD)), while keeping the content of PEO (2000 g/mol) constant (around 50%). To get a better insight into the effects of hard segment structure on gas transport properties, a series of aromatic polyimides with the same chemistry was also studied. Both series of polymers were characterized by ¹HNMR, FTIR, WAXD, DSC, TGA, and AFM. Permeabilities for pure He, O₂, N₂, and CO₂ were determined at 6 bar and at 30 °C, and for CO₂ for pressures ranging from 1 to 10 bar. The results show that OPDA-ODA-PEO is the most permeable copolyimide, with CO₂ permeability of 52 Barrer and CO₂/N₂ selectivity of 63, in contrast to its fully aromatic analogue, which was the least permeable among polyimides. 6FDA-4MPD-PEO ranks second, with a two times lower CO₂ permeability and slightly lower selectivity, although 6FDA-4MPD was over 900 times more permeable than OPDA-ODA. As an explanation, partial filling of hard domain free voids by PEO segments and imperfect phase separation were proposed. Full article

(This article belongs to the Special Issue Carbon Dioxide Capture Based on Polymeric Membrane)

► Show Figures

Figure 1

21 pages, 5011 KiB

Open AccessArticle

Ultra-High Packing Density Next Generation Microtube Array Membrane for Absorption Based Applications

by Chee Ho Chew, Wan-Ting Huang, Tzu-Sen Yang, Amanda Chen, Yun Ming Wu, Mai-Szu Wu and Chien-Chung Chen

Membranes 2021, 11(4), 273; https://doi.org/10.3390/membranes11040273 - 08 Apr 2021

Cited by 3 | Viewed by 2262

Abstract

Previously, we successfully developed an extracorporeal endotoxin removal device (EERD) that is based on the novel next generation alternating microtube array membrane (MTAM-A) that was superior to the commercial equivalent. In this article, we demonstrated multiple different parameter modifications that led to multiple [...] Read more.

Previously, we successfully developed an extracorporeal endotoxin removal device (EERD) that is based on the novel next generation alternating microtube array membrane (MTAM-A) that was superior to the commercial equivalent. In this article, we demonstrated multiple different parameter modifications that led to multiple different types of novel new MTAM structures, which ultimately led to the formation of the MTAM-A. Contrary to the single layered MTAM, the MTAM-A series consisted of a superior packing density fiber connected in a double layered, alternating position which allowed for the greater fiber count to be packed per unit area. The respective MTAM variants were electrospun by utilizing our internally developed tri-axial electrospinning set up to produce the novel microstructures as seen in the respective MTAM variants. A key uniqueness of this study is the ability to produce self-arranged fibers into the respective MTAM variants by utilizing a single spinneret, which has not been demonstrated before. Of the MTAM variants, we observed a change in the microstructure from a single layered MTAM to the MTAM-A series when the ratio of surfactant to shell flow rate approaches 1:1.92. MTAM-A registered the greatest surface area of 2.2 times compared to the traditional single layered MTAM, with the greatest tensile strength at 1.02 ± 0.13 MPa and a maximum elongation of 57.70 ± 9.42%. The MTAM-A was selected for downstream immobilization of polymyxin B (PMB) and assembly into our own internally developed and fabricated dialyzer housing. Subsequently, the entire setup was tested with whole blood spiked with endotoxin; and benchmarked against commercial Toraymyxin fibers of the same size. The results demonstrated that the EERD based on the MTAM-A performed superior to that of the commercial equivalent, registering a rapid reduction of 73.18% of endotoxin (vs. Toraymyxin at 38.78%) at time point 15 min and a final total endotoxin removal of 89.43% (vs. Toraymyxin at 65.03%). Full article

(This article belongs to the Special Issue Membrane Systems for Tissue Engineering 2020)

► Show Figures

Graphical abstract

12 pages, 1816 KiB

Open AccessArticle

Nanofiltration of Multi-Ion Solutions: Quantitative Control of Concentration Polarization and Interpretation by Solution-Diffusion-Electro-Migration Model

by Marc Fernández de Labastida and Andriy Yaroshchuk

Membranes 2021, 11(4), 272; https://doi.org/10.3390/membranes11040272 - 08 Apr 2021

Cited by 7 | Viewed by 2126

Abstract

For effective use of advanced engineering models of nanofiltration quality of experimental input is crucial, especially in electrolyte mixtures where simultaneous rejections of various ions may be very different. In particular, this concerns the quantitative control of concentration polarization (CP). This work used [...] Read more.

For effective use of advanced engineering models of nanofiltration quality of experimental input is crucial, especially in electrolyte mixtures where simultaneous rejections of various ions may be very different. In particular, this concerns the quantitative control of concentration polarization (CP). This work used a rotating disklike membrane test cell with equally accessible membrane surface, so the CP extent was the same over the membrane surface. This condition, which is not satisfied in the conventional membrane test cell, made possible correcting for CP easily even in multi-ion systems. Ion rejections were studied experimentally for several dominant salts (NaCl, MgCl₂, Na₂SO₄ and MgSO₄) and trace ions (Na⁺, NH₄⁺, Cl⁻ and NO₃⁻) using NF270 membrane. The solution–diffusion–electro–migration model was used to obtain ion permeances from the experimental measurements. The model could well fit the experimental data except in the case of NH₄⁺. The correlations between the ion permeances and type of dominant salt are discussed in the context of the established mechanisms of NF such as Donnan and dielectric exclusion. The obtained information contributes to the systematic transport characterization of NF membranes and may be ultimately useful for computational fluid dynamics simulations of the performance of the membranes in various applications. Full article

(This article belongs to the Special Issue New Phenomenological Findings in Nanofiltration)

► Show Figures

Figure 1

14 pages, 4521 KiB

Open AccessArticle

Innovative Gas-Liquid Membrane Contactor Systems for Carbon Capture and Mineralization in Energy Intensive Industries

by Akrivi Asimakopoulou, Dimitrios Koutsonikolas, Georgia Kastrinaki and George Skevis

Membranes 2021, 11(4), 271; https://doi.org/10.3390/membranes11040271 - 08 Apr 2021

Cited by 4 | Viewed by 3262

Abstract

CO₂ mineralization is an alternative to conventional geological storage and results in permanent carbon storage as a solid, with no need for long-term monitoring and no requirements for significant energy input. Novel technologies for carbon dioxide capture and mineralization involve the use [...] Read more.

CO₂ mineralization is an alternative to conventional geological storage and results in permanent carbon storage as a solid, with no need for long-term monitoring and no requirements for significant energy input. Novel technologies for carbon dioxide capture and mineralization involve the use of gas-liquid membrane contactors for post-combustion capture. The scope of the present study is to investigate the application of hollow fiber membrane contactor technology for combined CO₂ capture from energy-intensive industry flue gases and CO₂ mineralization, in a single-step multiphase process. The process is also a key enabler of the circular economy for the cement industry, a major contributor in global industrial CO₂ emissions, as CaCO₃ particles, obtained through the mineralization process, can be directed back into the cement production as fillers for partially substituting cement in high-performance concrete. High CO₂ capture efficiency is achieved, as well as CaCO₃ particles of controlled size and crystallinity are synthesized, in every set of operating parameters employed. The intensified gas-liquid membrane process is assessed by calculating an overall process mass transfer coefficient accounting for all relevant mass transfer resistances and the enhanced mass transfer due to reactive conditions on the shell side. The obtained nanocomposite particles have been extensively characterized by DLS, XRD, TGA, SEM, TEM, and FTIR studies, revealing structured aggregates (1–2 μm average aggregate size) consisting of cubic calcite when the contactor mode is employed. Full article

► Show Figures

Graphical abstract

12 pages, 1311 KiB

Open AccessArticle

Mode of Death after Extracorporeal Cardiopulmonary Resuscitation

by Viviane Zotzmann, Corinna N. Lang, Xavier Bemtgen, Markus Jäckel, Annabelle Fluegler, Jonathan Rilinger, Christoph Benk, Christoph Bode, Alexander Supady, Tobias Wengenmayer and Dawid L. Staudacher

Membranes 2021, 11(4), 270; https://doi.org/10.3390/membranes11040270 - 08 Apr 2021

Cited by 8 | Viewed by 2369

Abstract

Introduction: Extracorporeal cardiopulmonary resuscitation (ECPR) might be a lifesaving therapy for patients with cardiac arrest and no return of spontaneous circulation during advanced life support. However, even with ECPR, mortality of these severely sick patients is high. Little is known on the exact [...] Read more.

Introduction: Extracorporeal cardiopulmonary resuscitation (ECPR) might be a lifesaving therapy for patients with cardiac arrest and no return of spontaneous circulation during advanced life support. However, even with ECPR, mortality of these severely sick patients is high. Little is known on the exact mode of death in these patients. Methods: Retrospective registry analysis of all consecutive patients undergoing ECPR between May 2011 and May 2020 at a single center. Mode of death was judged by two researchers. Results: A total of 274 ECPR cases were included (age 60.0 years, 47.1% shockable initial rhythm, median time-to-extracorporeal membrane oxygenation (ECMO) 53.8min, hospital survival 25.9%). The 71 survivors had shorter time-to-ECMO durations (46.0 ± 27.9 vs. 56.6 ± 28.8min, p < 0.01), lower initial lactate levels (7.9 ± 4.5 vs. 11.6 ± 8.4 mg/dL, p < 0.01), higher PREDICT-6h (41.7 ± 17.0% vs. 25.3 ± 19.0%, p < 0.01), and SAVE (0.4 ± 4.8 vs. −0.8 ± 4.4, p < 0.01) scores. Most common mode of death in 203 deceased patients was therapy resistant shock in 105/203 (51.7%) and anoxic brain injury in 69/203 (34.0%). Comparing patients deceased with shock to those with cerebral damage, patients with shock were significantly older (63.2 ± 11.5 vs. 54.3 ± 16.5 years, p < 0.01), more frequently resuscitated in-hospital (64.4% vs. 29.9%, p < 0.01) and had shorter time-to-ECMO durations (52.3 ± 26.8 vs. 69.3 ± 29.1min p < 0.01). Conclusions: Most patients after ECPR decease due to refractory shock. Older patients with in-hospital cardiac arrest might be prone to development of refractory shock. Only a minority die from cerebral damage. Research should focus on preventing post-CPR shock and treating the shock in these patients. Full article

(This article belongs to the Special Issue Advances in Extracorporeal Membrane Oxygenation)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Membranes, Volume 11, Issue 4 (April 2021) – 70 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI