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Membranes
Volume 10
Issue 7
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Membranes, Volume 10, Issue 7 (July 2020) – 24 articles

Cover Story (view full-size image): Electrodialysis (ED) of both a conventional or unconventional fashion has been tested to treat several waste or spent aqueous solutions, including effluents from various industrial processes, municipal wastewater or salt water treatment plants, and animal farms. ED technologies can be used in the operation of concentration, dilution, desalination, regeneration, and valorisation to recover water and/or other products, e.g., heavy metal ions, salts, acids/bases, nutrients and organics, or electrical energy. Enhanced or novel systems have shown that zero or minimal liquid discharge approaches can be techno-economically affordable and competitive, thus opening new routes for the large-scale use of ED techniques. View this paper
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15 pages, 3640 KiB  
Article
An On-Board Pure H2 Supply System Based on A Membrane Reactor for A Fuel Cell Vehicle: A Theoretical Study
by Payam Parvasi, Seyyed Mohammad Jokar, Angelo Basile and Adolfo Iulianelli
Membranes 2020, 10(7), 159; https://doi.org/10.3390/membranes10070159 - 21 Jul 2020
Cited by 10 | Viewed by 3007
Abstract
In this novel conceptual fuel cell vehicle (FCV), an on-board CH4 steam reforming (MSR) membrane reformer (MR) is considered to generate pure H2 for supplying a Fuel Cell (FC) system, as an alternative to the conventional automobile engines. Two on-board tanks [...] Read more.
In this novel conceptual fuel cell vehicle (FCV), an on-board CH4 steam reforming (MSR) membrane reformer (MR) is considered to generate pure H2 for supplying a Fuel Cell (FC) system, as an alternative to the conventional automobile engines. Two on-board tanks are forecast to store CH4 and water, useful for feeding both a combustion chamber (designed to provide the heat required by the system) and a multi tubes Pd-Ag MR useful to generate pure H2 via methane steam reforming (MSR) reaction. The pure H2 stream is hence supplied to the FC. The flue gas stream coming out from the combustion chamber is used to preheat the MR feed stream by two heat exchangers and one evaporator. Then, this theoretical work demonstrates by a 1-D model the feasibility of the MR based system in order to generate 5 kg/day of pure H2 required by the FC system for cruising a vehicle for around 500 km. The calculated CH4 and water consumptions were 50 and 70 kg, respectively, per 1 kg of pure H2. The on-board MR based FCV presents lower CO2 emission rates than a conventional gasoline-powered vehicle, also resulting in a more environmentally friendly solution. Full article
(This article belongs to the Special Issue Membrane Reactors for Process Intensification: Recent Advances and Key Applications)
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24 pages, 9739 KiB  
Article
Mitigation of Membrane Wetting by Applying a Low Temperature Membrane Distillation
by Marek Gryta
Membranes 2020, 10(7), 158; https://doi.org/10.3390/membranes10070158 - 21 Jul 2020
Cited by 12 | Viewed by 2513
Abstract
The formation of deposits on the membrane surface during membrane distillation is considered as one of the main reasons for membrane wetting. To assess the intensity of this phenomenon, long-term studies were performed comparing the membrane wettability with non-fouling feed (NaCl solutions) and [...] Read more.
The formation of deposits on the membrane surface during membrane distillation is considered as one of the main reasons for membrane wetting. To assess the intensity of this phenomenon, long-term studies were performed comparing the membrane wettability with non-fouling feed (NaCl solutions) and feeds containing various foulants (lake and Baltic Sea water). The polypropylene membranes used were non-wetted by NaCl solutions during several hundred hours of water desalination. However, the occurrence of CaCO3 or other salt crystallization caused the membranes to be partially wetted, especially when periodical membrane cleaning was applied. The scaling intensity was significantly reduced by lowering the feed temperature from 353 to 315 K, which additionally resulted in the limitation of the degree of membrane wetting. Full article
(This article belongs to the Special Issue In Process Wetting Prevention in Membrane Distillation)
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16 pages, 6160 KiB  
Article
WO3/Buckypaper Membranes for Advanced Oxidation Processes
by Giovanni De Filpo, Elvira Pantuso, Aleksander I. Mashin, Mariafrancesca Baratta and Fiore Pasquale Nicoletta
Membranes 2020, 10(7), 157; https://doi.org/10.3390/membranes10070157 - 20 Jul 2020
Cited by 8 | Viewed by 2841
Abstract
Photocatalytic materials, such as WO3, TiO2, and ZnO nanoparticles, are commonly linked onto porous polymer membranes for wastewater treatment, fouling mitigation and permeation enhancement. Buckypapers (BPs) are entanglements of carbon nanotubes, which have been recently proposed as innovative filtration [...] Read more.
Photocatalytic materials, such as WO3, TiO2, and ZnO nanoparticles, are commonly linked onto porous polymer membranes for wastewater treatment, fouling mitigation and permeation enhancement. Buckypapers (BPs) are entanglements of carbon nanotubes, which have been recently proposed as innovative filtration systems thanks to their mechanical, electronic, and thermal properties. In this work, flexible membranes of single wall carbon nanotubes are prepared and characterized as efficient substrates to deposit by chemical vapor deposition thin layers of WO3 and obtain, in such a way, WO3/BP composite membranes for application in advanced oxidation processes. The photocatalytic efficiency of WO3/BP composite membranes is tested against model pollutants in a small continuous flow reactor and compared with the performance of an equivalent homogeneous WO3-based reactor. Full article
(This article belongs to the Special Issue Membranes: 10th Anniversary)
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15 pages, 2908 KiB  
Article
Experimental Design as a Tool for Optimizing and Predicting the Nanofiltration Performance by Treating Antibiotic-Containing Wastewater
by Dalva Inês de Souza, Alexandre Giacobbo, Eduardo da Silva Fernandes, Marco Antônio Siqueira Rodrigues, Maria Norberta de Pinho and Andréa Moura Bernardes
Membranes 2020, 10(7), 156; https://doi.org/10.3390/membranes10070156 - 19 Jul 2020
Cited by 20 | Viewed by 2958
Abstract
In recent years, there has been an increase in studies regarding nanofiltration-based processes for removing antibiotics and other pharmaceutical compounds from water and wastewater. In this work, a 2k factorial design with five control factors (antibiotic molecular weight and concentration, nanofiltration (NF) [...] Read more.
In recent years, there has been an increase in studies regarding nanofiltration-based processes for removing antibiotics and other pharmaceutical compounds from water and wastewater. In this work, a 2k factorial design with five control factors (antibiotic molecular weight and concentration, nanofiltration (NF) membrane, feed flow rate, and transmembrane pressure) was employed to optimize the NF performance on the treatment of antibiotic-containing wastewater. The resulting multiple linear regression model was used to predict the antibiotic rejections and permeate fluxes. Additional experiments, using the same membranes and the same antibiotics, but under different conditions of transmembrane pressure, feed flow rate, and antibiotic concentration regarding the 2k factorial design were carried out to validate the model developed. The model was also evaluated as a tertiary treatment of urban wastewater for removing sulfamethoxazole and norfloxacin. Considering all the conditions investigated, the tightest membrane (NF97) showed higher antibiotics rejection (>97%) and lower permeate fluxes. On the contrary, the loose NF270 membrane presented lower rejections to sulfamethoxazole, the smallest antibiotic, varying from 65% to 97%, and permeate fluxes that were about three-fold higher than the NF97 membrane. The good agreement between predicted and experimental values (R2 > 0.97) makes the model developed in the present work a tool to predict the NF performance when treating antibiotic-containing wastewater. Full article
(This article belongs to the Special Issue Membranes: 10th Anniversary)
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17 pages, 5259 KiB  
Article
Magnetically Aligned and Enriched Pathways of Zeolitic Imidazolate Framework 8 in Matrimid Mixed Matrix Membranes for Enhanced CO2 Permeability
by Machiel van Essen, Esther Montrée, Menno Houben, Zandrie Borneman and Kitty Nijmeijer
Membranes 2020, 10(7), 155; https://doi.org/10.3390/membranes10070155 - 17 Jul 2020
Cited by 13 | Viewed by 3291
Abstract
Metal-organic frameworks (MOFs) as additives in mixed matrix membranes (MMMs) for gas separation have gained significant attention over the past decades. Many design parameters have been investigated for MOF based MMMs, but the spatial distribution of the MOF throughout MMMs lacks investigation. Therefore, [...] Read more.
Metal-organic frameworks (MOFs) as additives in mixed matrix membranes (MMMs) for gas separation have gained significant attention over the past decades. Many design parameters have been investigated for MOF based MMMs, but the spatial distribution of the MOF throughout MMMs lacks investigation. Therefore, magnetically aligned and enriched pathways of zeolitic imidazolate framework 8 (ZIF−8) in Matrimid MMMs were synthesized and investigated by means of their N2 and CO2 permeability. Magnetic ZIF−8 (m–ZIF−8) was synthesized by incorporating Fe3O4 in the ZIF−8 structure. The presence of Fe3O4 in m–ZIF−8 showed a decrease in surface area and N2 and CO2 uptake, with respect to pure ZIF−8. Alignment of m–ZIF−8 in Matrimid showed the presence of enriched pathways of m–ZIF−8 through the MMMs. At 10 wt.% m–ZIF−8 incorporation, no effect of alignment was observed for the N2 and CO2 permeability, which was ascribed anon-ideal tortuous alignment. However, alignment of 20 wt.% m–ZIF−8 in Matrimid showed to increase the CO2 diffusivity and permeability (19%) at 7 bar, while no loss in ideal selectivity was observed, with respect to homogeneously dispersed m–ZIF−8 membranes. Thus, the alignment of MOF particles throughout the matrix was shown to enhance the CO2 permeability at a certain weight content of MOF. Full article
(This article belongs to the Special Issue Mixed Matrix Membranes II. From Lab Scale towards Application)
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18 pages, 3413 KiB  
Article
CO2/N2 Separation Properties of Polyimide-Based Mixed-Matrix Membranes Comprising UiO-66 with Various Functionalities
by Chong Yang Chuah, Junghyun Lee, Juha Song and Tae-Hyun Bae
Membranes 2020, 10(7), 154; https://doi.org/10.3390/membranes10070154 - 17 Jul 2020
Cited by 38 | Viewed by 5226
Abstract
Nanocrystalline UiO-66 and its derivatives (containing -NH2, -Br, -(OH)2) were developed via pre-synthetic functionalization and incorporated into a polyimide membrane to develop a mixed-matrix membrane (MMM) for CO2/N2 separation. Incorporation of the non-functionalized UiO-66 nanocrystals into [...] Read more.
Nanocrystalline UiO-66 and its derivatives (containing -NH2, -Br, -(OH)2) were developed via pre-synthetic functionalization and incorporated into a polyimide membrane to develop a mixed-matrix membrane (MMM) for CO2/N2 separation. Incorporation of the non-functionalized UiO-66 nanocrystals into the polyimide membrane successfully improved CO2 permeability, with a slight decrease in CO2/N2 selectivity, owing to its large accessible surface area. The addition of other functional groups further improved the CO2/N2 selectivity of the polymeric membrane, with UiO-66-NH2, UiO-66-Br, and UiO-66-(OH)2 demonstrating improvements of 12%, 4%, and 17%, respectively. Further evaluation by solubility–diffusivity analysis revealed that the functionalized UiO-66 in MMMs can effectively increase CO2 diffusivity while suppressing N2 sorption, thus, resulting in improved CO2/N2 selectivity. Such results imply that the structural tuning of UiO-66 by the incorporation of various functional groups is an effective strategy to improve the CO2 separation performance of MMMs. Full article
(This article belongs to the Special Issue Metal-Organic Framework Membranes for Molecular Separations)
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25 pages, 7382 KiB  
Article
Effect of the Formation of Ultrathin Selective Layers on the Structure and Performance of Thin-Film Composite Chitosan/PAN Membranes for Pervaporation Dehydration
by Mariia Dmitrenko, Andrey Zolotarev, Tatiana Plisko, Katsiaryna Burts, Vladislav Liamin, Alexandr Bildyukevich, Sergey Ermakov and Anastasia Penkova
Membranes 2020, 10(7), 153; https://doi.org/10.3390/membranes10070153 - 16 Jul 2020
Cited by 12 | Viewed by 3098
Abstract
The aim of the study is to improve the performance of thin-film composite (TFC) membranes with a thin selective layer based on chitosan (CS) via different approaches by: (1) varying the concentration of the CS solution; (2) changing the porosity of substrates from [...] Read more.
The aim of the study is to improve the performance of thin-film composite (TFC) membranes with a thin selective layer based on chitosan (CS) via different approaches by: (1) varying the concentration of the CS solution; (2) changing the porosity of substrates from polyacrylonitrile (PAN); (3) deposition of the additional ultrathin layers on the surface of the selective CS layer using interfacial polymerization and layer-by-layer assembly. The developed membranes were characterized by different methods of analyses (SEM and AFM, IR spectroscopy, measuring of water contact angles and porosity). The transport characteristics of the developed TFC membranes were studied in pervaporation separation of isopropanol/water mixtures. It was found that the application of the most porous PAN-4 substrate with combination of formation of an additional polyamide selective layer by interfacial polymerization on the surface of a dense selective CS layer with the subsequent layer-by-layer deposition of five bilayers of poly (sodium 4-styrenesulfonate)/CS polyelectrolyte pair led to the significant improvement of permeance and high selectivity for the entire concentration feed range. Thus, for TFC membrane on the PAN-4 substrate the optimal transport characteristics in pervaporation dehydration of isopropanol (12–90 wt.% water) were achieved: 0.22–1.30 kg/(m2h), 99.9 wt.% water in the permeate. Full article
(This article belongs to the Special Issue Progress in Manufacturing and Applications of Composite Membranes)
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24 pages, 3856 KiB  
Article
Experimental Investigation of the Oxidative Coupling of Methane in a Porous Membrane Reactor: Relevance of Back-Permeation
by Aitor Cruellas, Wout Ververs, Martin van Sint Annaland and Fausto Gallucci
Membranes 2020, 10(7), 152; https://doi.org/10.3390/membranes10070152 - 14 Jul 2020
Cited by 8 | Viewed by 2417
Abstract
Novel reactor configurations for the oxidative coupling of methane (OCM), and in particular membrane reactors, contribute toward reaching the yield required to make the process competitive at the industrial scale. Therefore, in this work, the conventional OCM packed bed reactor using a Mn-Na [...] Read more.
Novel reactor configurations for the oxidative coupling of methane (OCM), and in particular membrane reactors, contribute toward reaching the yield required to make the process competitive at the industrial scale. Therefore, in this work, the conventional OCM packed bed reactor using a Mn-Na2WO4/SiO2 catalyst was experimentally compared with a membrane reactor, in which a symmetric MgO porous membrane was integrated. The beneficial effects of distributive feeding of oxygen along the membrane, which is the main advantage of the porous membrane reactor, were demonstrated, although no significant differences in terms of performance were observed because of the adverse effects of back-permeation prevailing in the experiments. A sensitivity analysis carried out on the effective diffusion coefficient also indicated the necessity of properly tuning the membrane properties to achieve the expected promising results, highlighting how this tuning could be addressed. Full article
(This article belongs to the Special Issue Membrane Reactors for Process Intensification: Recent Advances and Key Applications)
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22 pages, 4275 KiB  
Article
Electrical, Dielectric Property and Electrochemical Performances of Plasticized Silver Ion-Conducting Chitosan-Based Polymer Nanocomposites
by Jihad M. Hadi, Shujahadeen B. Aziz, Muaffaq M. Nofal, Sarkawt A. Hussein, Muhamad H. Hafiz, Mohamad A. Brza, Rebar T. Abdulwahid, Mohd F. Z. Kadir and Haw J. Woo
Membranes 2020, 10(7), 151; https://doi.org/10.3390/membranes10070151 - 13 Jul 2020
Cited by 72 | Viewed by 4607
Abstract
In the present work, chitosan (CS) as a natural biopolymer was used to prepare nanocomposite polymer electrolytes (NCPEs) in order to reduce plastic waste pollution. The plasticized CS-based NCSPE has been prepared via the solution casting technique. The electrical properties of the films [...] Read more.
In the present work, chitosan (CS) as a natural biopolymer was used to prepare nanocomposite polymer electrolytes (NCPEs) in order to reduce plastic waste pollution. The plasticized CS-based NCSPE has been prepared via the solution casting technique. The electrical properties of the films were investigated using AC conductivity, dielectric properties, electric modulus, and electrical impedance spectroscopy (EIS). The obtained results from the dielectric properties and electric modulus study confirm the non-Debye behavior of ion dynamics. The effect of glycerol plasticizer on ionic conductivity of the CS:AgNO3:Al2O3 system was investigated via AC conductivity and impedance studies. The conductivity of the samples was explained based on electrical equivalent circuits and Bode plots. The electrochemical properties such as transfer number measurement (TNM), linear sweep voltammetry (LSV), and cyclic voltammetry (CV) were carried out to inspect the sample suitability for electrochemical double-layer capacitor (EDLC) application. The highest conductivity was 3.7 × 10−4 S cm−1 with the electrochemical stability window up to 2.1 V at room temperature. Through the TNM study, the ionic conductivity of plasticized CS-based NCSPE was confirmed, and ion transport (tion) of the highest conducting sample was found to be 0.985. The activated carbon electrode with the highest conducting sample was employed in the EDLC device fabrication. Accordingly, it can be said that the highest conducting sample had capable performance to be applied in electrochemical device application. Full article
(This article belongs to the Special Issue Polymeric Membrane)
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18 pages, 4012 KiB  
Article
Preparation of an Ultrafiltration (UF) Membrane with Narrow and Uniform Pore Size Distribution via Etching of SiO2 Nano-Particles in a Membrane Matrix
by Bushra Khan, Sajjad Haider, Rooha Khurram, Zhan Wang and Xi Wang
Membranes 2020, 10(7), 150; https://doi.org/10.3390/membranes10070150 - 10 Jul 2020
Cited by 10 | Viewed by 5233
Abstract
The UF membrane with a narrow and uniform pore size distribution and a low tendency to foul has significant applications in wastewater treatment. A major hindrance in the preparation of the UF membrane with these features is the lack of a scalable and [...] Read more.
The UF membrane with a narrow and uniform pore size distribution and a low tendency to foul has significant applications in wastewater treatment. A major hindrance in the preparation of the UF membrane with these features is the lack of a scalable and economical membrane fabrication method. Herein, we devise a new strategy to prepare a high-quality polyvinylidene fluoride/polymethyl acrylate/cellulose acetate (PVDF/PMMA/CA) blend UF membrane via a combination of the etching mechanism with the traditional Loeb–Sourirajan (L-S) phase inversion method. Different concentrations of silicon dioxide (SiO2) nanoparticles (NP) in the membrane matrix were etched by using a 0.2 M hydrofluoric acid (HF) solution in a coagulation bath. This strategy provided the membrane with unique features along with a narrow and uniform pore size distribution (0.030 ± 0.005 μm). The etched membrane exhibits an increase of 2.3 times in pure water flux (PWF) and of 6.5 times in permeate flux(PF), with a slight decrease in rejection ratio (93.2% vs. 97%) when compared to than that of the un-etched membrane. Moreover, this membrane displayed outstanding antifouling ability, i.e., a flux recovery ratio (FRR) of 97% for 1000 mg/L bovine serum albumin (BSA) solution, a low irreversible fouling ratio of 0.5%, and highly enhanced hydrophilicity due to the formation of pores/voids throughout the membrane structure. The aforementioned features of the etched membrane indicate that the proposed method of etching SiO2 NP in membrane matrix has a great potential to improve the structure and separation efficiency of a PVDF/PMMA/CA blend membrane. Full article
(This article belongs to the Section Membrane Chemistry)
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12 pages, 3826 KiB  
Article
Fouling Mechanisms Analysis via Combined Fouling Models for Surface Water Ultrafiltration Process
by Bin Huang, Hangkun Gu, Kang Xiao, Fangshu Qu, Huarong Yu and Chunhai Wei
Membranes 2020, 10(7), 149; https://doi.org/10.3390/membranes10070149 - 10 Jul 2020
Cited by 21 | Viewed by 3719
Abstract
Membrane fouling is still the bottleneck affecting the technical and economic performance of the ultrafiltration (UF) process for the surface water treatment. It is very important to accurately understand fouling mechanisms to effectively prevent and control UF fouling. The rejection performance and fouling [...] Read more.
Membrane fouling is still the bottleneck affecting the technical and economic performance of the ultrafiltration (UF) process for the surface water treatment. It is very important to accurately understand fouling mechanisms to effectively prevent and control UF fouling. The rejection performance and fouling mechanisms of the UF membrane for raw and coagulated surface water treatment were investigated under the cycle operation of constant-pressure dead-end filtration and backwash. There was no significant difference in the UF permeate quality of raw and coagulated surface water. Coagulation mainly removed substances causing turbidity in raw surface water (including most suspended particles and a few organic colloids) and thus mitigated UF fouling effectively. Backwash showed limited fouling removal. For the UF process of both raw and coagulated surface water, the fittings using single models showed good linearity for multiple models mainly due to statistical illusions, while the fittings using combined models showed that only the combined complete blocking and cake layer model fitted well. The quantitative calculations showed that complete blocking was the main reason causing flux decline. Membrane fouling mechanism analysis based on combined models could provide theoretical supports to prevent and control UF fouling for surface water treatment. Full article
(This article belongs to the Special Issue Membranes for Water and Wastewater Treatment)
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16 pages, 7661 KiB  
Article
In Situ Raman Characterization of SOFC Materials in Operational Conditions: A Doped Ceria Study
by Cecilia Solís, María Balaguer and José M. Serra
Membranes 2020, 10(7), 148; https://doi.org/10.3390/membranes10070148 - 10 Jul 2020
Cited by 5 | Viewed by 3504
Abstract
The particular operational conditions of electrochemical cells make the simultaneous characterization of both structural and transport properties challenging. The rapidity and flexibility of the acquisition of Raman spectra places this technique as a good candidate to measure operating properties and changes. Raman spectroscopy [...] Read more.
The particular operational conditions of electrochemical cells make the simultaneous characterization of both structural and transport properties challenging. The rapidity and flexibility of the acquisition of Raman spectra places this technique as a good candidate to measure operating properties and changes. Raman spectroscopy has been applied to well-known lanthanide ceria materials and the structural dependence on the dopant has been extracted. The evolution of Pr-doped ceria with temperature has been recorded by means of a commercial cell showing a clear increment in oxygen vacancies concentration. To elucidate the changes undergone by the electrolyte or membrane material in cell operation, the detailed construction of a homemade Raman cell is reported. The cell can be electrified, sealed and different gases can be fed into the cell chambers, so that the material behavior in the reaction surface and species evolved can be tracked. The results show that the Raman technique is a feasible and rather simple experimental option for operating characterization of solid-state electrochemical cell materials, although the treatment of the extracted data is not straightforward. Full article
(This article belongs to the Special Issue Membranes for Fuel Cells)
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15 pages, 1634 KiB  
Article
Evaluation of an Integrated Ultrafiltration/Solid Phase Extraction Process for Purification of Oligomeric Grape Seed Procyanidins
by Alba Gutierrez-Docio, Paula Almodóvar, Silvia Moreno-Fernandez, Jose Manuel Silvan, Adolfo J. Martinez-Rodriguez, Gonzalo Luis Alonso and Marin Prodanov
Membranes 2020, 10(7), 147; https://doi.org/10.3390/membranes10070147 - 09 Jul 2020
Cited by 6 | Viewed by 2898
Abstract
The effectiveness of a preparative integrated ultrafiltration/solid-phase extraction (UF/SPE) process for purification of oligomeric procyanidins (OPCs) from a crude grape seed extract (GSE) was studied for the first time. The separation of OPCs from polymeric procyanidins (PPCs) by UF was very efficient. The [...] Read more.
The effectiveness of a preparative integrated ultrafiltration/solid-phase extraction (UF/SPE) process for purification of oligomeric procyanidins (OPCs) from a crude grape seed extract (GSE) was studied for the first time. The separation of OPCs from polymeric procyanidins (PPCs) by UF was very efficient. The membrane showed an acceptable filtration flux of 6 to 3.5 L/h·m2 at 0.5 bar of transmembrane pressure and 95% recovery of its water flux after chemical cleaning. The process was scalable to a pilot scale. The separation of very polar and ionic species from OPCs by SPE (XAD7HP and XAD16 resins) was also very good, but both adsorbents lost their retention capacities quickly, due probably to irreversible retention of OPCs/PPCs. Even though the global purification of OPCs by the integrated UF/SPE process allowed the recovery of 24.2 g of highly purified OPCs (83% purity) from 14.4 L of crude grape seed extract, the use of these adsorbents for further purification of the OPCs was very limited. Full article
(This article belongs to the Special Issue Integrated Membrane Systems and Processes)
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93 pages, 18781 KiB  
Review
Electrodialysis Applications in Wastewater Treatment for Environmental Protection and Resources Recovery: A Systematic Review on Progress and Perspectives
by Luigi Gurreri, Alessandro Tamburini, Andrea Cipollina and Giorgio Micale
Membranes 2020, 10(7), 146; https://doi.org/10.3390/membranes10070146 - 09 Jul 2020
Cited by 222 | Viewed by 20569
Abstract
This paper presents a comprehensive review of studies on electrodialysis (ED) applications in wastewater treatment, outlining the current status and the future prospect. ED is a membrane process of separation under the action of an electric field, where ions are selectively transported across [...] Read more.
This paper presents a comprehensive review of studies on electrodialysis (ED) applications in wastewater treatment, outlining the current status and the future prospect. ED is a membrane process of separation under the action of an electric field, where ions are selectively transported across ion-exchange membranes. ED of both conventional or unconventional fashion has been tested to treat several waste or spent aqueous solutions, including effluents from various industrial processes, municipal wastewater or salt water treatment plants, and animal farms. Properties such as selectivity, high separation efficiency, and chemical-free treatment make ED methods adequate for desalination and other treatments with significant environmental benefits. ED technologies can be used in operations of concentration, dilution, desalination, regeneration, and valorisation to reclaim wastewater and recover water and/or other products, e.g., heavy metal ions, salts, acids/bases, nutrients, and organics, or electrical energy. Intense research activity has been directed towards developing enhanced or novel systems, showing that zero or minimal liquid discharge approaches can be techno-economically affordable and competitive. Despite few real plants having been installed, recent developments are opening new routes for the large-scale use of ED techniques in a plethora of treatment processes for wastewater. Full article
(This article belongs to the Special Issue Electromembrane Processes: Experiments and Modelling)
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14 pages, 4626 KiB  
Article
Influence of Surface Modification of MK-40 Membrane with Polyaniline on Scale Formation under Electrodialysis
by Marina A. Andreeva, Natalia V. Loza, Natalia D. Pis’menskaya, Lasaad Dammak and Christian Larchet
Membranes 2020, 10(7), 145; https://doi.org/10.3390/membranes10070145 - 07 Jul 2020
Cited by 16 | Viewed by 2491
Abstract
A comprehensive study of the polyaniline influence on mineral scaling on the surface of the heterogeneous MK-40 sulfocationite membrane under electrodialysis has been conducted. Current-voltage curves and chronopotentiograms have been obtained and analyzed for the pristine MK-40 membrane and the MK-40 membrane which [...] Read more.
A comprehensive study of the polyaniline influence on mineral scaling on the surface of the heterogeneous MK-40 sulfocationite membrane under electrodialysis has been conducted. Current-voltage curves and chronopotentiograms have been obtained and analyzed for the pristine MK-40 membrane and the MK-40 membrane which is surface-modified by polyaniline. The study of the electrochemical behavior of membranes has been accompanied by the simultaneous control of the pH of the solution outcoming from the desalination compartment. The mixture of Na2CO3, KCl, CaCl2, and MgCl2 is used as a model salt solution. Two limiting states are observed on the current-voltage curve of the surface-modified membrane. There is the first pseudo-limiting state in the range of small values of the potential drop. The second limiting current is comparable with that of the limiting current for the pristine membrane. It is shown that chronopotentiometry cannot be used as a self-sufficient method for membrane scaling identification on the surface-modified membrane at high currents. A mineral scale on the surfaces of the studied membranes has been found by scanning electron microscopy. The amount of precipitate is higher in the case of the surface-modified membrane compared with the pristine one. Full article
(This article belongs to the Special Issue In-Depth on the Fouling and Antifouling of Ion-Exchange Membranes)
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18 pages, 4780 KiB  
Article
Porous Gelatin Membranes Obtained from Pickering Emulsions Stabilized with h-BNNS: Application for Polyelectrolyte-Enhanced Ultrafiltration
by Molka Nafti Mateur, Danae Gonzalez Ortiz, Dorra Jellouli Ennigrou, Karima Horchani-Naifer, Mikhael Bechelany, Philippe Miele and Céline Pochat-Bohatier
Membranes 2020, 10(7), 144; https://doi.org/10.3390/membranes10070144 - 07 Jul 2020
Cited by 9 | Viewed by 3462
Abstract
In recent years, numerous studies have been conducted to develop biopolymer-based membranes, highlighting the challenges to prepare porous structures with control porosity. In this paper an innovative method that relies on the generation of Pickering emulsions was developed to prepare porous membranes from [...] Read more.
In recent years, numerous studies have been conducted to develop biopolymer-based membranes, highlighting the challenges to prepare porous structures with control porosity. In this paper an innovative method that relies on the generation of Pickering emulsions was developed to prepare porous membranes from gelatin for filtration purpose. Hexagonal boron nitride nanosheets (h-BNNS) were used to stabilize micro-droplets of castor oil in a continuous homogeneous gelatin solution. Two steps in the membrane preparation process strongly influenced the porous structure. Specifically, the duration of the drying time after emulsion casting and the duration of the cross-linking step affected membrane pore size, hydrophobicity, water swelling, and water permeability. By controlling these two steps, membranes could be designed with pore size between 0.39 and 1.60 μm and display pure water permeability between 150 and 506 L h−1 m−2 bar−1. These membranes have been tested for complexation–ultrafiltration experiments in which iron ions were removed from aqueous solutions with/without poly (acrylic acid) (PAA). Without PAA, the removal of free iron (II) ions was low (not more than 14%). The addition of PAA (200 ppm) allowed obtaining high removal rates (97%) at pH ≥ 5 with 3 bars of transmembrane pressure. Full article
(This article belongs to the Special Issue Polymeric Membrane)
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20 pages, 9559 KiB  
Article
Hydrophilic Dual Layer Hollow Fiber Membranes for Ultrafiltration
by Lara Grünig, Ulrich A. Handge, Joachim Koll, Oliver Gronwald, Martin Weber, Birgit Hankiewicz, Nico Scharnagl and Volker Abetz
Membranes 2020, 10(7), 143; https://doi.org/10.3390/membranes10070143 - 06 Jul 2020
Cited by 10 | Viewed by 3874
Abstract
In this study, a triblock copolymer was used as additive to fabricate new dual layer hollow fiber membranes with a hydrophilic active inner surface in order to improve their fouling resistance. The polymeric components of the solutions for membrane fabrication were poly(ether sulfone), [...] Read more.
In this study, a triblock copolymer was used as additive to fabricate new dual layer hollow fiber membranes with a hydrophilic active inner surface in order to improve their fouling resistance. The polymeric components of the solutions for membrane fabrication were poly(ether sulfone), poly(N-vinyl pyrrolidone), and the triblock copolymer. The additive consists of three blocks: a middle hydrophobic poly(ether sulfone) block and two outer hydrophilic alkyl poly(ethylene glycol) blocks. By varying the additive concentration in the solutions, it was possible to fabricate dual layer hollow fiber membranes that are characterized by a hydrophilic inner layer, a pure water permeance of over 1800 L/(m2 bar h) and a molecular weight cut-off of 100 kDa similar to commercial membranes. Contact angle and composition determination by XPS measurements revealed the hydrophilic character of the membranes, which improved with increasing additive concentration. Rheological, dynamic light scattering, transmission, and cloud point experiments elucidated the molecular interaction, precipitation, and spinning behavior of the solutions. The low-molecular weight additive reduces the solution viscosity and thus the average relaxation time. On the contrary, slow processes appear with increasing additive concentration in the scattering data. Furthermore, phase separation occurred at a lower non-solvent concentration and the precipitation time increased with increasing additive content. These effects revealed a coupling mechanism of the triblock copolymer with poly(N-vinyl pyrrolidone) in solution. The chosen process parameters as well as the additive solutions provide an easy and inexpensive way to create an antifouling protection layer in situ with established recipes of poly(ether sulfone) hollow fiber membranes. Therefore, the membranes are promising candidates for fast integration in the membrane industry. Full article
(This article belongs to the Special Issue Membranes: 10th Anniversary)
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13 pages, 2430 KiB  
Article
Study on the Concentration of Acrylic Acid and Acetic Acid by Reverse Osmosis
by Qian Liu, Lixin Xie, Hanxiao Du, Shichang Xu and Yawei Du
Membranes 2020, 10(7), 142; https://doi.org/10.3390/membranes10070142 - 06 Jul 2020
Cited by 6 | Viewed by 2717
Abstract
In the production of acrylic acid, the concentration of acrylic acid solution from the adsorption tower was low, which would lead to significant energy consumption in the distillation process to purify acrylic acid, along with the production of a large amount of wastewater. [...] Read more.
In the production of acrylic acid, the concentration of acrylic acid solution from the adsorption tower was low, which would lead to significant energy consumption in the distillation process to purify acrylic acid, along with the production of a large amount of wastewater. Reverse osmosis (RO) was proposed to concentrate the acrylic acid aqueous solution taken from a specific tray in the absorption tower. The effects of operating conditions on the permeate flux and acid retention were studied with two commercial RO membranes (SWC5 and SWC6). When the operating pressure was 4 MPa and the temperature was 25 °C, the permeate fluxes of two membranes were about 20 L·m−2·h−1. The acrylic acid and acetic acid retentions were about 80% and 78%, respectively. After being immersed in the acid solutions for several months, the characteristics of the two membranes were tested to evaluate their acid resistance. After six months of exposure to the acid solution containing 2.5% acrylic acid and 2.5% acetic acid, the retentions of acrylic acid and acetic acid were decreased by 5.7% and 4.1% for SWC5 and 4.9% and 2.2% for SWC6, respectively. The changes of membrane surface morphology and chemical composition showed the hydrolysis of some amide bonds. Full article
(This article belongs to the Section Membrane Processing and Engineering)
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18 pages, 4802 KiB  
Article
New Poly(imide)s Bearing Alkyl Side-Chains: A Study on the Impact of Size and Shape of Lateral Groups on Thermal, Mechanical, and Gas Transport Properties
by Fidel E. Rodríguez-González, Germán Pérez, Vladimir Niebla, Ignacio Jessop, Rudy Martin-Trasanco, Deysma Coll, Pablo Ortiz, Manuel Aguilar-Vega, Luis H. Tagle, Claudio A. Terraza and Alain Tundidor-Camba
Membranes 2020, 10(7), 141; https://doi.org/10.3390/membranes10070141 - 04 Jul 2020
Cited by 5 | Viewed by 2719
Abstract
A set of five new aromatic poly(imide)s (PIs) incorporating pendant acyclic alkyl moieties were synthesized. The difference among them was the length and bulkiness of the pendant group, which comprises of linear alkyl chains from three to six carbon atoms, and a tert [...] Read more.
A set of five new aromatic poly(imide)s (PIs) incorporating pendant acyclic alkyl moieties were synthesized. The difference among them was the length and bulkiness of the pendant group, which comprises of linear alkyl chains from three to six carbon atoms, and a tert-butyl moiety. The effect of the side group length on the physical, thermal, mechanical, and gas transport properties was analyzed. All PIs exhibited low to moderate molecular weights (Mn ranged between 27.930–58.970 Da, and Mw ranged between 41.760–81.310 Da), good solubility in aprotic polar solvents, except for PI-t-4, which had a tert-butyl moiety and was soluble even in chloroform. This behaviour was probably due to the most significant bulkiness of the side group that increased the interchain distance, which was corroborated by the X-ray technique (PI-t-4 showed two d-spacing values: 5.1 and 14.3 Å). Pure gas permeabilities for several gases were reported (PI-3 (Barrer): He(52); H2(46); O2(5.4); N2(1.2); CH4(1.1); CO2(23); PI-t-4 (Barrer): He(139); H2(136); O2(16.7); N2(3.3); CH4(2.3); CO2(75); PI-5 (Barrer): He(44); H2(42); O2(5.9); N2(1.4); CH4(1.2); CO2(27); PI-6 (Barrer): He(45); H2(43); O2(6.7); N2(1.7); CH4(1.7); CO2(32)). Consistent higher volume in the side group was shown to yield the highest gas permeability. All poly(imide)s exhibited high thermal stability with 10% weight loss degradation temperature between 448–468 °C and glass transition temperature between 240–270 °C. The values associated to the tensile strength (45–87 MPa), elongation at break (3.2–11.98%), and tensile modulus (1.43–2.19 GPa) were those expected for aromatic poly(imide)s. Full article
(This article belongs to the Special Issue Polymer Membranes for Gas Separation)
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29 pages, 4785 KiB  
Review
Recent Developments in Nanomaterials-Modified Membranes for Improved Membrane Distillation Performance
by Saikat Sinha Ray, Harshdeep Singh Bakshi, Raghav Dangayach, Randeep Singh, Chinmoy Kanti Deb, Mahesh Ganesapillai, Shiao-Shing Chen and Mihir Kumar Purkait
Membranes 2020, 10(7), 140; https://doi.org/10.3390/membranes10070140 - 03 Jul 2020
Cited by 67 | Viewed by 8004
Abstract
Membrane distillation (MD) is a thermally induced membrane separation process that utilizes vapor pressure variance to permeate the more volatile constituent, typically water as vapor, across a hydrophobic membrane and rejects the less volatile components of the feed. Permeate flux decline, membrane fouling, [...] Read more.
Membrane distillation (MD) is a thermally induced membrane separation process that utilizes vapor pressure variance to permeate the more volatile constituent, typically water as vapor, across a hydrophobic membrane and rejects the less volatile components of the feed. Permeate flux decline, membrane fouling, and wetting are some serious challenges faced in MD operations. Thus, in recent years, various studies have been carried out on the modification of these MD membranes by incorporating nanomaterials to overcome these challenges and significantly improve the performance of these membranes. This review provides a comprehensive evaluation of the incorporation of new generation nanomaterials such as quantum dots, metalloids and metal oxide-based nanoparticles, metal organic frameworks (MOFs), and carbon-based nanomaterials in the MD membrane. The desired characteristics of the membrane for MD operations, such as a higher liquid entry pressure (LEPw), permeability, porosity, hydrophobicity, chemical stability, thermal conductivity, and mechanical strength, have been thoroughly discussed. Additionally, methodologies adopted for the incorporation of nanomaterials in these membranes, including surface grafting, plasma polymerization, interfacial polymerization, dip coating, and the efficacy of these modified membranes in various MD operations along with their applications are addressed. Further, the current challenges in modifying MD membranes using nanomaterials along with prominent future aspects have been systematically elaborated. Full article
(This article belongs to the Special Issue Membranes: 10th Anniversary)
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18 pages, 4186 KiB  
Article
Computational Fluid Dynamics (CFD) Modeling and Simulation of Flow Regulatory Mechanism in Artificial Kidney Using Finite Element Method
by Tuba Yaqoob, Muhammad Ahsan, Arshad Hussain and Iftikhar Ahmad
Membranes 2020, 10(7), 139; https://doi.org/10.3390/membranes10070139 - 03 Jul 2020
Cited by 5 | Viewed by 4344
Abstract
There is an enormous need in the health welfare sector to manufacture inexpensive dialyzer membranes with minimum dialysis duration. In order to optimize the dialysis cost and time, an in-depth analysis of the effect of dialyzer design and process parameters on toxins (ranging [...] Read more.
There is an enormous need in the health welfare sector to manufacture inexpensive dialyzer membranes with minimum dialysis duration. In order to optimize the dialysis cost and time, an in-depth analysis of the effect of dialyzer design and process parameters on toxins (ranging from tiny to large size molecules) clearance rate is required. Mathematical analysis and enhanced computational power of computers can translate the transport phenomena occurring inside the dialyzer while minimizing the development cost. In this paper, the steady-state mass transport in blood and dialysate compartment and across the membrane is investigated with convection-diffusion equations and tortuous pore diffusion model (TPDM), respectively. The two-dimensional, axisymmetric CFD model was simulated by using a solver based on the finite element method (COMSOL Multiphysics 5.4). The effect of design and process parameters is analyzed by solving model equations for varying values of design and process parameters. It is found that by introducing tortuosity in the pore diffusion model, the clearance rate of small size molecules increases, but the clearance rate of large size molecules is reduced. When the fiber aspect ratio (db/L) varies from 900 to 2300, the clearance rate increases 37.71% of its initial value. The results also show that when the pore diameter increases from 10 nm to 20 nm, the clearance rate of urea and glucose also increases by 2.09% and 7.93%, respectively, with tolerated transport of albumin molecules. Full article
(This article belongs to the Special Issue Flow and Transport in Membranes: Modeling and Experimental Verification)
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14 pages, 2756 KiB  
Article
Anion Exchange Membranes Prepared from Quaternized Polyepichlorohydrin Cross-Linked with 1-(3-aminopropyl)imidazole Grafted Poly(arylene ether ketone) for Enhancement of Toughness and Conductivity
by Cao Manh Tuan, Vo Dinh Cong Tinh and Dukjoon Kim
Membranes 2020, 10(7), 138; https://doi.org/10.3390/membranes10070138 - 30 Jun 2020
Cited by 13 | Viewed by 3898
Abstract
A novel anion exchange membrane was synthesized via crosslinking of the quaternized polyepichlorohydrin (QPECH) by 1-(3-aminopropyl) imidazole grafted poly(arylene ether ketone) (PAEK-API). While the QPECH provided an excellent ion conductive property, the rigid rod-structured PAEK-API played a reinforcing role, along with providing the [...] Read more.
A novel anion exchange membrane was synthesized via crosslinking of the quaternized polyepichlorohydrin (QPECH) by 1-(3-aminopropyl) imidazole grafted poly(arylene ether ketone) (PAEK-API). While the QPECH provided an excellent ion conductive property, the rigid rod-structured PAEK-API played a reinforcing role, along with providing the high conductivity associated with the pendant API group. The chemical structure of QPECH/PAEK-API membranes was identified by 1H nuclear magnetic resonace spectroscopy. A variety of membrane properties, such as anion conductivity, water uptake, length swelling percentage, and thermal, mechanical and chemical stability, were investigated. The QPECH/PAEK-API1 membrane showed quite high hydroxide ion conductivity, from 0.022 S cm−1 (30 °C) to 0.033 S cm−1 (80 °C), and excellent mechanical strength, associated with the low water uptake of less than 40%, even at 80 °C. Such high conductivity at relatively low water uptake is attributed to the concentrated cationic groups, in a cross-linked structure, facilitating feasible ion transport. Further, the QPECH/PAEK-API membranes showed thermal stability up to 250 °C, and chemical stability for 30 days in a 4 NaOH solution, without significant loss of ion exchange capacity. Full article
(This article belongs to the Special Issue Polymer Electrolyte Membranes)
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14 pages, 6034 KiB  
Article
Fabrication of High-Performance Thin-Film Composite Nanofiltration Membrane by Dynamic Calcium-Carboxyl Intra-Bridging during Post-Treatment
by Hongyi Han, Ruobin Dai and Zhiwei Wang
Membranes 2020, 10(7), 137; https://doi.org/10.3390/membranes10070137 - 30 Jun 2020
Cited by 15 | Viewed by 3624
Abstract
Widespread applications of nanofiltration (NF) and reverse osmosis (RO)-based processes for water purification and desalination call for high-performance thin-film composite (TFC) membranes. In this work, a novel and facile modification method was proposed to fabricate high-performance thin-film composite nanofiltration membrane by introducing Ca [...] Read more.
Widespread applications of nanofiltration (NF) and reverse osmosis (RO)-based processes for water purification and desalination call for high-performance thin-film composite (TFC) membranes. In this work, a novel and facile modification method was proposed to fabricate high-performance thin-film composite nanofiltration membrane by introducing Ca2+ in the heat post-treatment. The introduction of Ca2+ induced in situ Ca2+-carboxyl intra-bridging, leading to the embedment of Ca2+ in the polyamide (PA) layer. This post modification enhanced the hydrophilicity and surface charge of NF membranes compared to the pristine membrane. More interestingly, the modified membrane had more nodules and exhibited rougher morphology. Such changes brought by the addition of Ca2+ enabled the significant increase of water permeability (increasing from 17.9 L·m−2·h−1·bar−1 to 29.8 L·m−2·h−1·bar−1) while maintaining a high selectivity (Na2SO4 rejection rate of 98.0%). Furthermore, the intra-bridging between calcium and carboxyl imparted the NF membranes with evident antifouling properties, exhibiting milder permeability decline of 4.2% (compared to 16.7% of NF-control) during filtration of sodium alginate solution. The results highlight the potential of using Ca2+-carboxyl intra-bridging post-treatment to fabricate high-performance TFC membranes for water purification and desalination. Full article
(This article belongs to the Special Issue Membranes for Water and Wastewater Treatment)
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25 pages, 3530 KiB  
Article
Experimental and Theoretical Analysis of Lead Pb2+ and Cd2+ Retention from a Single Salt Using a Hollow Fiber PES Membrane
by Salwa Hadi, Ahmed A. Mohammed, Sama M. Al-Jubouri, Mahmood F. Abd, Hasan Shaker Majdi, Qusay F. Alsalhy, Khalid T. Rashid, Salah S. Ibrahim, Issam K. Salih and Alberto Figoli
Membranes 2020, 10(7), 136; https://doi.org/10.3390/membranes10070136 - 30 Jun 2020
Cited by 20 | Viewed by 3519
Abstract
The present work reports the performance of three types of polyethersulfone (PES) membrane in the removal of highly polluting and toxic lead Pb2+ and cadmium Cd2+ ions from a single salt. This study investigated the effect of operating variables, including pH, [...] Read more.
The present work reports the performance of three types of polyethersulfone (PES) membrane in the removal of highly polluting and toxic lead Pb2+ and cadmium Cd2+ ions from a single salt. This study investigated the effect of operating variables, including pH, types of PES membrane, and feed concentration, on the separation process. The transport parameters and mass transfer coefficient (k) of the membranes were estimated using the combined film theory-solution-diffusion (CFSD), combined film theory-Spiegler-Kedem (CFSK), and combined film theory-finely-porous (CFFP) membrane transport models. Various parameters were used to estimate the enrichment factors, concentration polarization modulus, and Péclet number. The pH values significantly affected the permeation flux of the Pb2+ solution but only had a slight effect on the Cd2+ solution. However, Cd2+ rejection was highly improved by increasing the pH value. The rejection of the PES membranes increased greatly as the heavy metal concentration rose, while the heavy metal concentration moderately affected the permeation flux. The maximum rejection of Pb2+ in a single-salt solution was 99%, 97.5%, and 98% for a feed solution containing 10 mg Pb/L at pH 6, 6.2, and 5.7, for PES1, PES2, and PES3, respectively. The maximum rejection of Cd2+ in single-salt solutions was 78%, 50.2%, and 44% for a feed solution containing 10 mg Cd/L at pH 6.5, 6.2, and 6.5, for PES1, PES2, and PES3, respectively. The analysis of the experimental data using the CFSD, CFSK, and CFFP models showed a good agreement between the theoretical and experimental results. The effective membrane thickness and active skin layer thickness were evaluated using the CFFP model, indicating that the Péclet number is important for determining the mechanism of separation by diffusion. Full article
(This article belongs to the Special Issue Membrane Preparation and Characterisation and Their Application in Environmental Field (Volume II))
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