Membrane Separation Technology Research

Abstract submission deadline

15 July 2025

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15 September 2025

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Topic Information

Dear Colleagues,

Membrane processes are separation processes, where the transported components can be separated employing a semipermeable polymeric or inorganic membrane with a particular structure. Membrane processes can generally occur without introducing additional chemicals to the feed stream and thus separate products according to their size, charges, and Gibbs hydration energy. Therefore, the membrane process, which is a type of rate-based separation using pressure (ΔP), electric (ΔE), and stream concentration (ΔC) as driving factors, has been widely utilized in the sectors of saltwater desalination, green chemical engineering, and wastewater treatment. This Topic aims to cover the latest achievements in innovative membrane materials and membrane processes. Original research and review papers with emphasis on, but not limited to, the following topics are welcome:

1. Membrane processes for desalination, classification, and purification;
2. Fabrication of new membrane materials;
3. Membrane processes integration, optimization, and intensification;
4. Membrane simulation and process modeling.

Dr. Chenxiao Jiang
Dr. Zhe Yang
Dr. Ying Mei
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.0	6.2	2008	16.8 Days	CHF 2600	Submit
International Journal of Molecular Sciences ijms	4.9	8.1	2000	16.8 Days	CHF 2900	Submit
Membranes membranes	3.3	6.1	2011	14.9 Days	CHF 2200	Submit
Separations separations	2.5	3.0	2014	15.1 Days	CHF 2600	Submit
Water water	3.0	5.8	2009	17.5 Days	CHF 2600	Submit

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Published Papers (16 papers)

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Supplementary material:
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15 pages, 4108 KiB  

Open AccessArticle

Improved CO₂/CH₄ Separation in Carbon Molecular Sieve Membranes via Copolymerization of Long-Chain Flexible Structures

by Yingxiu Wu, Haiyan Guo, Bingyu Zhao, Yuxiu Yu, Yaodong Liu and Shouchun Zhang

Membranes 2025, 15(5), 128; https://doi.org/10.3390/membranes15050128 (registering DOI) - 27 Apr 2025

Abstract

Carbon molecular sieve (CMS) membranes demonstrate considerable advantages and significant potential in the separation of CO₂ and CH₄. Nevertheless, current research predominantly emphasizes the enhancement of CMS membranes through the incorporation of rigid structures and chain spatial stacking. The role [...] Read more.

Carbon molecular sieve (CMS) membranes demonstrate considerable advantages and significant potential in the separation of CO₂ and CH₄. Nevertheless, current research predominantly emphasizes the enhancement of CMS membranes through the incorporation of rigid structures and chain spatial stacking. The role of flexible structures in this context remains inadequately understood. To address this gap, we introduced long-chain polydimethylsiloxane (PDMS) and copolymerized it to synthesize polyimide that combines rigid and flexible frameworks. This approach enabled us to investigate the impact of flexible structures on the structure and properties of carbon membranes by varying the PDMS content. The findings indicated that flexible PDMS significantly influenced the thermal decomposition behavior of polyimide and facilitated in situ silicon doping within the carbon membranes, thereby modifying the pore characteristics of the carbon film. Specifically, with a 10% addition of PDMS, the CO₂ permeability of the CMS membrane reached 9556 Barrer, representing an enhancement of 103.9% and surpassing the 2019 upper bound for CO₂/CH₄ separation. Furthermore, the effect of pyrolysis temperature was also examined. Ultimately, this study offers a novel perspective on regulating the structural and performance characteristics of carbon membranes through the integration of long-chain flexible structures. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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14 pages, 6569 KiB  

Open AccessArticle

Pervaporation Dehydration Mechanism and Performance of High-Aluminum ZSM-5 Zeolite Membranes for Organic Solvents

by Qing Wang, Cheng Qian, Changxu Guo, Nong Xu, Qiao Liu, Bin Wang, Long Fan and Kunhong Hu

Int. J. Mol. Sci. 2024, 25(14), 7723; https://doi.org/10.3390/ijms25147723 - 14 Jul 2024

Cited by 2 | Viewed by 1883

Abstract

Membrane-based pervaporation (PV) for organic solvent dehydration is of great significance in the chemical and petrochemical industries. In this work, high-aluminum ZSM-5 zeolite membranes were synthesized by a fluoride-assisted secondary growth on α-alumina tubular supports using mordenite framework inverted (MFI) nanoseeds (~110 nm) [...] Read more.

Membrane-based pervaporation (PV) for organic solvent dehydration is of great significance in the chemical and petrochemical industries. In this work, high-aluminum ZSM-5 zeolite membranes were synthesized by a fluoride-assisted secondary growth on α-alumina tubular supports using mordenite framework inverted (MFI) nanoseeds (~110 nm) and a template-free synthesis solution with a low Si/Al ratio of 10. Characterization by XRD, EDX, and SEM revealed that the prepared membrane was a pure-phase ZSM-5 zeolite membrane with a Si/Al ratio of 3.8 and a thickness of 2.8 µm. Subsequently, two categories of PV performance parameters (i.e., flux versus separation factor and permeance versus selectivity) were used to systematically examine the effects of operating conditions on the PV dehydration performance of different organic solvents (methanol, ethanol, n-propanol, and isopropanol), and their PV mechanisms were explored. Employing permeance and selectivity effectively disentangles the influence of operating conditions on PV performance, thereby elucidating the inherent contribution of membranes to separation performance. The results show that the mass transfer during PV dehydration of organic solvents was mainly dominated by the adsorption–diffusion mechanism. Furthermore, the diffusion of highly polar water and methanol molecules within membrane pores had a strong mutual slowing-down effect, resulting in significantly lower permeance than other binary systems. However, the mass transfer process for water/low-polar organic solvent (ethanol, n-propanol, and isopropanol) mixtures was mainly controlled by competitive adsorption caused by affinity differences. In addition, the high-aluminum ZSM-5 zeolite membrane exhibited superior PV dehydration performance for water/isopropanol mixtures. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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17 pages, 2913 KiB  

Open AccessArticle

Long-Term Performance Evaluation and Fouling Characterization of a Full-Scale Brackish Water Reverse Osmosis Desalination Plant

by Sabrine Chebil, A. Ruiz-García, Soumaya Farhat and Mahmoud Bali

Water 2024, 16(13), 1892; https://doi.org/10.3390/w16131892 - 1 Jul 2024

Cited by 1 | Viewed by 1585

Abstract

Water scarcity in Tunisia’s semi-arid regions necessitates advanced brackish water desalination solutions. This study evaluates the long-term performance and fouling characteristics of the largest brackish water reverse osmosis desalination plant in southern Tunisia over a period of 5026 days. The plant employs two-stage [...] Read more.

Water scarcity in Tunisia’s semi-arid regions necessitates advanced brackish water desalination solutions. This study evaluates the long-term performance and fouling characteristics of the largest brackish water reverse osmosis desalination plant in southern Tunisia over a period of 5026 days. The plant employs two-stage spiral-wound membrane elements to treat groundwater with a salinity of 3.2 g L⁻¹. The pre-treatment process includes oxidation, sand filtration, and cartridge filtration, along with polyphosphonate antiscalant dosing. Membrane performance was assessed through the analysis of operational data, standardization of permeate flow (Q_ps) and salt passage (SP_s), and the calculation of water (A), solute (B), and ionic (B_j) permeability coefficients. Over the operational period, there was an increase in operating pressure, pressure drop, and permeate conductivity, accompanied by a gradual increase in SP_s as well as in the solute B and ionic B_j permeability coefficients. The average B increased by 82%, reflecting a decrease in solute rejection over time. Additionally, the ionic permeability coefficients for both SO₄²⁻ and Cl⁻ ions increased, with Cl⁻ showing an 88% increase and SO₄²⁻ showing an 87% increase. The produced water’s salinity increased by 67%, indicating a significant loss of membrane performance. To identify the cause of these problems, membrane characterization was analyzed using visual inspection, X-ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR). The characterization revealed the complex nature of the foulants, with a predominant presence of calcium sulfate, along with minor quantities of calcite, dolomite, and silica. The extent of CaSO₄ deposition suggests poor antiscaling efficiency, highlighting the critical importance of selecting an effective antiscalant to mitigate membrane fouling. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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19 pages, 3832 KiB  

Open AccessArticle

Technical Feasibility of Extraction of Freshwater from Produced Water with Combined Forward Osmosis and Nanofiltration

by Madina Mohamed, Marco Tagliabue and Alberto Tiraferri

Membranes 2024, 14(5), 107; https://doi.org/10.3390/membranes14050107 - 3 May 2024

Cited by 2 | Viewed by 1641

Abstract

This study assesses the technical feasibility of a forward-osmosis-based system for concentrating produced water and extracting freshwater. Forward osmosis was combined with nanofiltration, the latter system used to restore the initial osmotic pressure of the diluted draw solutions while concurrently obtaining the final [...] Read more.

This study assesses the technical feasibility of a forward-osmosis-based system for concentrating produced water and extracting freshwater. Forward osmosis was combined with nanofiltration, the latter system used to restore the initial osmotic pressure of the diluted draw solutions while concurrently obtaining the final freshwater product. Three draw solutions, namely, MgCl₂, NaCl, and C₃H₅NaO₂, were initially tested against a synthetic water mimicking a pretreated produced water effluent having an osmotic pressure equal to 16.3 bar. MgCl₂ was thus selected for high-recovery experiments. Different combinations of draw solution osmotic pressure (30, 40, 60, 80, and 120) and draw-to-feed initial volume ratios (1, 1.6, and 2.2) were tested at the laboratory scale, achieving recovery rates between roughly 35% and 70% and water fluxes between 4 and 8 L m⁻²h⁻¹. One-dimensional, system-wide simulations deploying the analytical FO water flux equation were utilized to validate the experiments, investigate co-current and counter-current configurations, and understand the system potential. The diluted draw solutions were then transferred to nanofiltration to regenerate their original osmotic pressure. There, the highest observed rejection was 96.6% with an average flux of 21 L m⁻²h⁻¹, when running the system to achieve 100% relative recovery. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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13 pages, 1866 KiB  

Open AccessArticle

Constituents of Coliform Species Contained in the Permeate of Microfiltration Membranes in Wastewater Treatment

by Shuai Zhou, Taro Urase and Saki Goto

Water 2024, 16(9), 1269; https://doi.org/10.3390/w16091269 - 28 Apr 2024

Cited by 1 | Viewed by 1769

Abstract

MBRs (Membrane bioreactors) have been increasingly employed for municipal and industrial wastewater treatment in the last decades for their small footprint and excellent effluent quality. However, microorganisms are often detected in the permeates of microfiltration (MF) membranes even with small pore sizes. Coliform [...] Read more.

MBRs (Membrane bioreactors) have been increasingly employed for municipal and industrial wastewater treatment in the last decades for their small footprint and excellent effluent quality. However, microorganisms are often detected in the permeates of microfiltration (MF) membranes even with small pore sizes. Coliform bacteria are known for indicating the potential presence of pathogenic bacteria that cause infectious disease such as bacteremia, respiratory tract infections, and urinary tract infections. Thus, the retention of coliform bacteria by membrane processes is important when the membrane process is utilized in water reclamation. In this study, a microbial community of coliform bacteria in the permeates of MF membranes with different pore sizes (0.2, 0.4, and 0.8 µm) was identified. The results showed that the dominant coliform bacteria changed from Enterobacter spp. and Citrobacter spp. in the activated sludge to Enterobacter spp. and Klebsiella spp. in the permeate of MF membranes, while some pieces of membranes showed complete retention. The bacterial regrowth on the surface of the piping system on the permeate side could be a significant factor contributing to the frequent and exclusive detection of Enterobacter spp. and Klebsiella spp. in the case of membranes with small pore size (0.2 and 0.4 µm) after a long continuous filtration time. To indicate the public health-related risk of treated wastewater by MF, Escherichia coli may not be a suitable indicator species because E. coli is relatively retentive in MF compared to other coliforms. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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10 pages, 2659 KiB  

Open AccessCommunication

Experimental Study on the Separation of Lithium and Imidazolium Ions Using a Cation Exchange Membrane

by Jingyi Xue, Xiang Meng, Runci Wang, Zhongwei Yuan and Weifang Zheng

Separations 2024, 11(4), 123; https://doi.org/10.3390/separations11040123 - 19 Apr 2024

Viewed by 1523

Abstract

The separation of Li⁺ and [Bmim]⁺(1-Butyl-3-methylimidazolium) using a cation exchange membrane in an electric field is studied in this work. The effects of the type of cation exchange membrane, current density, total cation concentration, temperature, and anion types on the [...] Read more.

The separation of Li⁺ and [Bmim]⁺(1-Butyl-3-methylimidazolium) using a cation exchange membrane in an electric field is studied in this work. The effects of the type of cation exchange membrane, current density, total cation concentration, temperature, and anion types on the separation efficiency are investigated. The results indicate that it is feasible to achieve the efficient separation of Li⁺ and [Bmim]⁺ using the selectivity of cation exchange membranes under an electric field. The CIMS membrane (a type of cation exchange membrane produced by ASTOM Corporation) shows obvious selectivity of Li⁺ from [Bmim]⁺. When the current density is 5 mA/cm² and the feed concentrations of Li⁺ and [Bmim]⁺ are 0.3 mol/L and 0.2 mol/L, respectively, the selective transport coefficient of CIMS can reach 5.9 in the first 120 min of the process. The separation efficiency can be effectively improved by reducing the current density and increasing the total cation concentration. Decreasing the feed temperature can slightly improve the separation efficiency. Changing the type of anion in the feed from chloride to acetate has no detectable effect on the separation. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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13 pages, 1977 KiB  

Open AccessArticle

Impact of Ionic Strength and Charge Density on Donnan Potential in the NaCl-Cation Exchange Membrane System

by Baraa A. K. Al-Sakaji, Ghaleb A. Husseini and Naif A. Darwish

Water 2023, 15(21), 3830; https://doi.org/10.3390/w15213830 - 2 Nov 2023

Cited by 4 | Viewed by 2803

Abstract

This work aims to theoretically investigate the effect of both the fixed charge density of ion exchange membranes and the ionic strength of the treated aqueous NaCl solution on the generated Donnan potential at thermodynamic equilibrium conditions. The direct objective of our work [...] Read more.

This work aims to theoretically investigate the effect of both the fixed charge density of ion exchange membranes and the ionic strength of the treated aqueous NaCl solution on the generated Donnan potential at thermodynamic equilibrium conditions. The direct objective of our work is to calculate the equilibrium concentration of the Cl⁻ co-ion inside a swelled cation-exchange membrane equilibrated with a water/NaCl system. Two activity coefficient models are employed, i.e., the Debye–Huckel (DH) model (as a reference model) and the Meissner model, which is known for its applicability in treating concentrated solutions. Experimental data available in the literature for Donnan potential are used to verify model predictions. Our study confirms that a high fixed charge density is required to counterbalance the deterioration in membrane selectivity encountered in high-salinity systems. The DH model can be safely used to predict the Donnan potential for feed compositions up to 0.1 M. At higher compositions, the DH model significantly overestimates the predicted (absolute) Donnan potential compared to the Meissner model. The osmotic pressure resulting from the difference in ionic concentration between the membrane phase and the feed phase is found to have insignificant effects on the Donnan potential. The equilibrium computations and methodology are presented in a general way that enables handling multivalent electrolyte systems such as CaCl₂. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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12 pages, 2958 KiB  

Open AccessArticle

Study on the Treatment of Refined Sugar Wastewater by Electrodialysis Coupled with Upflow Anaerobic Sludge Blanket and Membrane Bioreactor

by Shichang Xu, Han Zhao, Lixin Xie, Keqiang Wang and Wen Zhang

Membranes 2023, 13(5), 527; https://doi.org/10.3390/membranes13050527 - 19 May 2023

Cited by 6 | Viewed by 1894

Abstract

In this paper, refined sugar wastewater (RSW) is treated by electrodialysis (ED) coupled with an upflow anaerobic sludge blanket (UASB) and membrane bioreactor (MBR). The salt in RSW was first removed by ED, and then the remaining organic components in RSW were degraded [...] Read more.

In this paper, refined sugar wastewater (RSW) is treated by electrodialysis (ED) coupled with an upflow anaerobic sludge blanket (UASB) and membrane bioreactor (MBR). The salt in RSW was first removed by ED, and then the remaining organic components in RSW were degraded by a combined UASB and MBR system. In the batch operation of ED, the RSW was desalinated to a certain level (conductivity < 6 mS·cm⁻¹) at different dilute to concentrated stream volume ratios (V_D/V_C). At the volume ratio of 5:1, the salt migration rate J_R and COD migration rate J_COD were 283.9 g·h⁻¹·m⁻² and 13.84 g·h⁻¹·m⁻², respectively, and the separation factor α (defined as J_COD/J_R) reached a minimum value of 0.0487. The ion exchange capacity (IEC) of ion exchange membranes (IEMs) after 5 months of usage showed a slight change from 2.3 mmol·g⁻¹ to 1.8 mmol·g⁻¹. After the ED treatment, the effluent from the tank of the dilute stream was introduced into the combined UASB-MBR system. In the stabilization stage, the average COD of UASB effluent was 2048 mg·L⁻¹, and the effluent COD of MBR was maintained below 44–69 mg·L⁻¹, which met the discharge standard of water contaminants for the sugar industry. The coupled method reported here provides a viable idea and an effective reference for treating RSW and other similar industrial wastewaters with high salinity and organic contents. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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14 pages, 5701 KiB  

Open AccessArticle

Alleviating Ultrafiltration Membrane Fouling Caused by Effluent Organic Matter Using Pre-Ozonation: A Perspective of EEM and Molecular Weight Distribution

by Kuo Gao, Hong Yang, Haichen Liu and Bingzhi Dong

Membranes 2023, 13(4), 452; https://doi.org/10.3390/membranes13040452 - 21 Apr 2023

Cited by 8 | Viewed by 1962

Abstract

Wastewater reclamation has gradually become an important way to cope with the global water crisis. Ultrafiltration plays an imperative part as a safeguard for the aim but is often limited by membrane fouling. Effluent organic matter (EfOM) has been known to be a [...] Read more.

Wastewater reclamation has gradually become an important way to cope with the global water crisis. Ultrafiltration plays an imperative part as a safeguard for the aim but is often limited by membrane fouling. Effluent organic matter (EfOM) has been known to be a major foulant during ultrafiltration. Hence, the primary aim of this study was to investigate the effects of pre-ozonation on the membrane fouling caused by EfOM in secondary wastewater effluents. In addition, the physicochemical property changes of EfOM during pre-ozonation and the subsequent influence on membrane fouling were systemically investigated. The combined fouling model and the morphology of fouled membrane were adopted to scrutinize the fouling alleviation mechanism by pre-ozonation. It was found that membrane fouling by EfOM was dominated by hydraulically reversible fouling. In addition, an obvious fouling reduction was achieved by pre-ozonation with 1.0 mg O₃/mg DOC. The resistance results showed that the normalized hydraulically reversible resistance was reduced by ~60%. The water quality analysis indicated that ozone degraded high molecular weight organics such as microbial metabolites and aromatic protein and medium molecular weight organics (humic acid-like) into smaller fractions and formed a looser fouling layer on the membrane surface. Furthermore, pre-ozonation made the cake layer foul towards pore blocking, thereby reducing fouling. In addition, there was a little degradation in the pollutant removal performance with pre-ozonation. The DOC removal rate decreased by more than 18%, while UV₂₅₄ decreased by more than 20%. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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16 pages, 1156 KiB  

Open AccessArticle

Experimental Study and Modeling of Beer Dealcoholization via Reverse Osmosis

by Áron Varga, Eszter Bihari-Lucena, Márta Ladányi, Beatrix Szabó-Nótin, Ildikó Galambos and András Koris

Membranes 2023, 13(3), 329; https://doi.org/10.3390/membranes13030329 - 13 Mar 2023

Cited by 3 | Viewed by 2853

Abstract

The goals of the present investigation are to study and to model pale lager beer dealcoholization via reverse osmosis (RO). Samples were dealcoholized at a temperature of 15 ± 1 °C. An Alfa Laval RO99 membrane with a 0.05 m² surface was [...] Read more.

The goals of the present investigation are to study and to model pale lager beer dealcoholization via reverse osmosis (RO). Samples were dealcoholized at a temperature of 15 ± 1 °C. An Alfa Laval RO99 membrane with a 0.05 m² surface was used. The flux values were measured during the separations. The ethanol content, extract content, bitterness, color, pH, turbidity, and dynamic viscosity of beer and permeate samples were measured. The initial flux values were determined using linear regression. The initial ethanol flux ($J_{EtOH 0}$) values were calculated from the initial flux values and the ethanol content values. A 2^P full factorial experimental design was applied, and the factors were as follows: transmembrane pressure (TMP): 10, 20, 30 bar; retentate flow rate (Q): 120, 180, 240 L/h; $J_{EtOH 0}$ was considered as the response. The effect sizes of the significant parameters were calculated. The global maximum of the objective function was found using a self-developed Grid Search code. The changes in the analytical parameters were appropriate. The TMP had a significant effect, while the Q had no significant effect on the $J_{EtOH 0}$. The effect size of the TMP was 1.20. The optimal value of the factor amounted to TMP = 30 bar. The predicted $J_{EtOH 0}$ under the above conditions was 121.965 g/m² h. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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14 pages, 3202 KiB  

Open AccessArticle

Improving the Separation Properties of Polybenzimidazole Membranes by Adding Acetonitrile for Organic Solvent Nanofiltration

by Ga Yeon Won, Ahrumi Park, Youngmin Yoo, You-In Park, Jung-Hyun Lee, In-Chul Kim, Young Hoon Cho and Hosik Park

Membranes 2023, 13(1), 104; https://doi.org/10.3390/membranes13010104 - 12 Jan 2023

Cited by 4 | Viewed by 2969

Abstract

In research on membranes, the addition of co-solvents to the polymer dope solution is a common method for tuning the morphology and separation performance. For organic solvent nanofiltration (OSN) applications, we synthesized polybenzimidazole (PBI) membranes with high separation properties and stability by adding [...] Read more.

In research on membranes, the addition of co-solvents to the polymer dope solution is a common method for tuning the morphology and separation performance. For organic solvent nanofiltration (OSN) applications, we synthesized polybenzimidazole (PBI) membranes with high separation properties and stability by adding acetonitrile (MeCN) to the dope solution, followed by crosslinking with dibromo-p-xylene. Accordingly, changes in the membrane structure and separation properties were investigated when MeCN was added. PBI/MeCN membranes with a dense and thick active layer and narrow finger-like macrovoids exhibited superior rejection properties in the ethanol solution compared with the pristine PBI membrane. After crosslinking, they displayed superior rejection properties (96.56% rejection of 366-g/mol polypropylene glycol). In addition, the membranes demonstrated stable permeances for various organic solvents, including acetone, methanol, ethanol, toluene, and isopropyl alcohol. Furthermore, to evaluate the feasibility of the modified PBI OSN membranes, ecamsule, a chemical product in the fine chemical industry, was recovered. Correspondingly, the efficient recovery of ecamsule from a toluene/methanol solution using the OSN process with PBI/MeCN membranes demonstrated their applicability in many fine chemical industries. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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14 pages, 4073 KiB  

Open AccessArticle

Preparation of Lateral Flow PVDF Membrane via Combined Vapor- and Non-Solvent-Induced Phase Separation (V-NIPS)

by Xiaoyun Wang, Dejian Chen, Ting He, Yue Zhou, Li Tian, Zhaohui Wang and Zhaoliang Cui

Membranes 2023, 13(1), 91; https://doi.org/10.3390/membranes13010091 - 10 Jan 2023

Cited by 9 | Viewed by 3482

Abstract

A large pore size Poly(vinylidene fluoride) (PVDF) membrane was prepared by the V-NIPS method using PVDF/N, N-dimethylacetamide (DMAc)/Polyvinyl pyrrolidone (PVP)/Polyethylene glycol (PEG) system. Firstly, the effect of different additive ratios on the membrane morphology and pore size was studied, and it was found [...] Read more.

A large pore size Poly(vinylidene fluoride) (PVDF) membrane was prepared by the V-NIPS method using PVDF/N, N-dimethylacetamide (DMAc)/Polyvinyl pyrrolidone (PVP)/Polyethylene glycol (PEG) system. Firstly, the effect of different additive ratios on the membrane morphology and pore size was studied, and it was found that when the PVP:PEG ratio was 8:2, PVDF membranes with a relatively large pore size tend to be formed; the pore size is about 7.5 µm. Then, the effects of different exposure time on the membrane morphology and pore size were investigated, and it was found that as the vapor temperature increased, the pores on the surface of the membrane first became slightly smaller and then increased. Finally, the effects of different vapor temperatures on the membrane properties were discussed. The results showed that the as-prepared membrane exhibited suitable capillary flow rate and similar performance compared with a commercially available membrane in colloidal gold tests. The likely cause is that the amount of negative charge is less and the capillary migration rate is too fast. This paper provides a reference for the preparation of PVDF colloidal gold detection membrane. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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27 pages, 3966 KiB  

Open AccessArticle

Techno-Economic Comparison of Integration Options for an Oxygen Transport Membrane Unit into a Coal Oxy-Fired Circulating Fluidized Bed Power Plant

by E. Portillo, Luz M. Gallego Fernández, M. Cano, B. Alonso-Fariñas and B. Navarrete

Membranes 2022, 12(12), 1224; https://doi.org/10.3390/membranes12121224 - 2 Dec 2022

Cited by 2 | Viewed by 2612

Abstract

The inclusion of membrane-based oxygen-fired combustion in power plants is considered an emerging technology that could reduce carbon emissions in a more efficient way than cryogenic oxygen-fired processes. In this paper, a techno-economic assessment was developed for a 863 MW_el,net power plant [...] Read more.

The inclusion of membrane-based oxygen-fired combustion in power plants is considered an emerging technology that could reduce carbon emissions in a more efficient way than cryogenic oxygen-fired processes. In this paper, a techno-economic assessment was developed for a 863 MW_el,net power plant to demonstrate whether this CCS technique results in a reduction in efficiency losses and economic demand. Four configurations based on oxygen transport membranes were considered, while the benchmark cases were the air combustion process without CO₂ capture and a cryogenic oxygen-fired process. The type of driving force through the membrane (3-end or 4-end), the point of integration into the oxy-fuel combustion process, the heating system, and the pollutant control system were aspects considered in this work. In comparison, the efficiency losses for membrane-based alternatives were lower than those in the cryogenic oxygen-fired process, reaching savings of up to 14% net efficiency. Regarding the specific energy consumption for CO₂ capture, the configuration based on the oxygen transport membrane unit with 4-end mode and hot filtration presented 1.01 kW_el,net,·h/kg_{CO2 captured} with 100% CO₂ recovery, which is an improvement of 11% compared with the cases using cryogenic oxygen. Comparing economic aspects, the specific investment costs for cases based on the oxygen transport membrane unit varied between 2520 and 2942 $/kW_el,net·h. This was between 39.6 and 48.2% above the investment for the reference case without carbon capture. However, its hypothetical implantation could suppose a savings of 10.7% in terms of investment cost compared with cryogenic oxygen-based case. In terms of the levelized cost of electricity and the cost of CO₂ avoidance, the oxygen transport membrane configurations achieved more favorable results compared with the cryogenic route, reaching savings up to 14 and 38%, respectively. Although oxygen transport membrane units are currently not mature for commercial-scale applications, the results indicated that its application within carbon capture and storage technologies can be strongly competitive. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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15 pages, 1634 KiB  

Open AccessArticle

Comparison of Membrane-Based Treatment Methods for the Removal of Micro-Pollutants from Reclaimed Water

by Sukanyah Devaisy, Jaya Kandasamy, Tien Vinh Nguyen, Md Abu Hasan Johir, Harsha Ratnaweera and Saravanamuthu Vigneswaran

Water 2022, 14(22), 3708; https://doi.org/10.3390/w14223708 - 16 Nov 2022

Cited by 9 | Viewed by 3507

Abstract

Dual membrane hybrid systems generally produce reclaimed water for non-potable uses by blending microfiltered biologically treated sewage effluent (BTSE) and reverse osmosis (RO) permeate. This reclaimed water is found to contain a significant amount of micro-pollutants, which possibly cause toxicity effects to aquatic [...] Read more.

Dual membrane hybrid systems generally produce reclaimed water for non-potable uses by blending microfiltered biologically treated sewage effluent (BTSE) and reverse osmosis (RO) permeate. This reclaimed water is found to contain a significant amount of micro-pollutants, which possibly cause toxicity effects to aquatic organisms and plants when exposed to it. Therefore, removing such pollutants from the reclaimed water before reaching the community is highly emphasized nowadays. The currently used treatment of the RO treatment of microfiltered BTSE is energy intensive and not cost effective. This paper focuses on less costly and efficient membrane-based hybrid treatment systems such as the microfiltration-adsorption (MF-GAC) hybrid system, Nano filter (NF) and RO in the removal of micro-pollutants from the microfiltered BTSE. Both the MF-GAC hybrid system and NF (with NTR 729HF membrane) removed 70 to 95% of micropollutants from microfiltered BTSE. The removal depends on the hydrophobicity, charge, and size of the micropollutants. RO was excellent in removing more than 90% of pollutants, while MF was inefficient, as the latter primarily depends on the size exclusion mechanism. Based on the finding, it is suggested to treat only a portion of microfiltered BTSE through the MF-GAC or NF membrane before blending with RO permeate to enhance the removal of micro-pollutants from reclaimed water. The development of sustainable hybrid systems for the removal of all micropollutants of different chemical and physical properties is the key for the water reclamation. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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21 pages, 10720 KiB  

Open AccessArticle

Ti₃C₂ MXene Membranes for Gas Separation: Influence of Heat Treatment Conditions on D-Spacing and Surface Functionalization

by Aline Alencar Emerenciano, Rubens Maribondo do Nascimento, Ana Paula Cysne Barbosa, Ke Ran, Wilhelm Albert Meulenberg and Jesus Gonzalez-Julian

Membranes 2022, 12(10), 1025; https://doi.org/10.3390/membranes12101025 - 21 Oct 2022

Cited by 25 | Viewed by 4789

Abstract

Two-dimensional (2D) MXene materials have recently been the focus of membrane research due to their unique properties, such as their single-atomic-layer thickness, flexibility, molecular filtration abilities and microstructural similarities with graphene, which is currently the most efficient precursor material for gas separation applications. [...] Read more.

Two-dimensional (2D) MXene materials have recently been the focus of membrane research due to their unique properties, such as their single-atomic-layer thickness, flexibility, molecular filtration abilities and microstructural similarities with graphene, which is currently the most efficient precursor material for gas separation applications. In addition, the potential to process nanoscale channels has motivated investigations of parameters which can improve membrane permeability and selectivity. Interlayer spacing and defects, which are still challenging to control, are among the most crucial parameters for membrane performance. Herein, the effect of heat treatment on the d-spacing of MXene nanosheets and the surface functionalization of nanolayers was shown regarding its impact on the gas diffusion mechanism. The distance of the layers was reduced by a factor of over 10 from 0.345 nm to 0.024 nm, the defects were reduced, and the surface functionalization was maintained upon treatment of the Ti₃C₂ membrane at 500 °C under an Ar/H₂ atmosphere as compared to 80 °C under vacuum. This led to a change from Knudsen diffusion to molecular sieving, as demonstrated by single-gas permeation tests at room temperature. Overall, this work shows a simple and promising way to improve H₂/CO₂ selectivity via temperature treatment under a controlled atmosphere. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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18 pages, 5313 KiB  

Open AccessArticle

Fouling and Performance Investigation of Membrane Distillation at Elevated Recoveries for Seawater Desalination and Wastewater Reclamation

by Abdulaziz Khan, Sudesh Yadav, Ibrar Ibrar, Raed A. Al Juboori, Sara Ali Razzak, Priyamjeet Deka, Senthilmurugan Subbiah and Shreyansh Shah

Membranes 2022, 12(10), 951; https://doi.org/10.3390/membranes12100951 - 28 Sep 2022

Cited by 11 | Viewed by 3297

Abstract

This study reports on the impact of elevated recovery (i.e., 80%, 85%, and 90%) on the fouling and performance of air gap membrane distillation (AGMD) with real seawater and landfill leachate wastewater samples using polytetrafluoroethylene (PTFE) polymer membranes. Increasing the feed temperature from [...] Read more.

This study reports on the impact of elevated recovery (i.e., 80%, 85%, and 90%) on the fouling and performance of air gap membrane distillation (AGMD) with real seawater and landfill leachate wastewater samples using polytetrafluoroethylene (PTFE) polymer membranes. Increasing the feed temperature from 55 °C to 65 °C improved the water flux of seawater and wastewater and shortened the operating time by 42.8% for all recoveries. The average water flux in the 80%, 85%, and 90% recovery experiments at the 65 °C feed temperature was 32%, 37.32%, and 36.7% higher than the case of 55 °C for the same recoveries. The water flux decline was more severe at a higher temperature and recovery. The highest flux decline was observed with a 90% recovery at 65 °C feed temperature, followed by an 85% recovery at 65 °C. Close examination of the foulants layer revealed that seawater formed a cake fouling layer made predominantly of metal oxides. In contrast, the landfill leachate fouling was a combination of pore blocking and cake formation, consisting mainly of carbonous and nitrogenous compounds. Physical cleaning with deionized (DI) water at 55 °C and 65 °C and chemical cleaning with hydrogen peroxide (H₂O₂) were investigated for their efficiency in removing membrane foulants. Analytical results revealed that seawater fouling caused membrane pore blockage while wastewater fouling formed a porous layer on the membrane surface. The results showed that membrane cleaning with hydrogen peroxide restored >97% of the water flux. Interestingly, the fouling factor in seawater tests was 10%, while it was 16% for the wastewater tests. Full article

(This article belongs to the Topic Membrane Separation Technology Research)

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