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Nanostructured Membranes II

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A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Inorganic Membranes".

Deadline for manuscript submissions: closed (31 August 2021) | Viewed by 30868

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Prof. Dr. Lingxue Kong

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Institute for Frontier Materials, Deakin University, Waurn Ponds, VIC 3216, Australia
Interests: nanostructured membranes; porous materials; membrane characterization
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Kuo-Lun Tung

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Advanced Research Center for Green Materials Science and Technology and Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
Interests: inorganic membrane fabrication; membrane filtration mechanism; membrane module design; multiscale simulation
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Dr. Xing Yang

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Department of Chemical Engineering, 3000 Leuven, Belgium
Interests: process intensification and integration for designing energy-efficient hybrid membrane systems; transport modeling and process simulation in the areas of resource recovery; bioseparation and chemical sensing
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Dr. Shuaifei Zhao

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Guest Editor

Institute for Frontier Materials, Deakin University, Waurn Ponds, VIC 3216, Australia
Interests: membrane separation; desalination, water treatment; gas separation; carbon capture and utilisation; resource recovery
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue came as the natural consequence of the great success of the previous Special Issue "Nanostructured Membranes".

The world’s growing population and demographic change demand the supply of an unprecedented volume of clean water to society. The increase in agricultural activities and industrialisation also generates a large amount of waste that will have significant implications for sustainable development. This has led to the development of innovative materials to be used in various separation industries.

The unique nanostructure and enhanced surface properties of nano-materials provide new perspectives on separation membranes. The surface energy, porosity, crystalline structure, and morphology at the nano-scale were shown to have a direct impact on the material’s plasmonic, magnetic, catalytic, thermodynamic, and filtering properties, opening a route to the design of exciting new membrane separation systems. The application of nanostructured materials in separation science, which is concerned with how to selectively reclaim solvents or remove contaminants from mainstreams, still, however, faces a number of challenges, largely related to particle agglomeration, high energy consumption, organic, inorganic, and biological fouling, mechanical and chemical stability of the nano-materials’ surface properties, and evident reproducibility due to the diverse range of existing synthesis techniques.

The performance of nanostructured membranes can be further augmented by the functionalisation of materials, either by introducing materials or modifying the surface with a novel functionality. Significant breakthroughs have particularly been made in combinatorial materials design, which aims to develop multi-functional hybrid systems.

The purpose of this Special Issue is to publish high-quality research papers as well as review articles addressing recent developments in the application of nanostructured membrane materials. We seek original, high-quality contributions that are yet to be published or that are not currently under review by other journals or peer-reviewed conferences.

Potential topics include, but are not limited to:

new nanoscale porous architectures;
strategies for the synthesis of novel materials for nanostructures
our understanding of fundamental interfacial interactions between nanomaterials and contaminants;
industrial exploration of nanostructured membranes;
modelling of fouling and scaling at the nanoscale;
novel strategies for incorporating catalytic materials into chemical reactors;
advanced catalytic coatings and surfaces;
photo-catalysis applied to liquid and gas remediation;
passivation and regeneration of nanocatalysts;
design of super-adsorbents;
super-adsorbents for solvent reclamation;
nanotextured or porous membrane materials;
flow enhancement across nanoporous membranes;
advanced technology for the characterisation of nanostructured membranes;
computational simulation of membrane processes; and
molecular dynamics simulation of flow and interfacial interaction.

Prof. Dr. Lingxue Kong
Prof. Dr. Kuo-Lun Tung
Prof. Dr. Xing Yang
Dr. Shuaifei Zhao
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Membranes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

nanostructure
surface interfacial interaction
super-adsorbents
modelling
functionalisation.

Published Papers (11 papers)

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Research

11 pages, 13487 KiB

Open AccessCommunication

Fast Reduced Graphene-Based Membranes with High Desalination Performance

by Shanshan Liang, Liuyuan Zhu, Shuai Wang, Liang Chen and Haiping Fang

Membranes 2021, 11(11), 846; https://doi.org/10.3390/membranes11110846 - 29 Oct 2021

Cited by 3 | Viewed by 1944

Abstract

Graphene-oxide (GO) membrane with notable ions sieving properties has attracted significant attention for many applications. However, because of the water swelling of GO membrane, the rejection of monovalent metal cations is generally low. In this work, we developed a fast and facile method to fabricate a kind of reduced GO membranes using the thermal treatment method at 160 °C for only one minute, which denoted as fast reduced GO membrane (FRGO). Surprising, the FRGO membrane represents high ion sieving ability and ultrahigh water/ions selectivity, compared with other reduced GO membranes with similar average interlayer spacings, and even superior to most of GO-based membranes reported in literature. Building on these findings, we provide a new light on fabricating of energy- and environment-related high desalination performance of GO-based membranes as well as a new insight into the transport mechanism within 2D laminar nanochannels. Full article

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

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11 pages, 2547 KiB

Open AccessArticle

Towards a High-Flux Separation Layer from Hexagonal Lyotropic Liquid Crystals for Thin-Film Composite Membranes

by Senlin Gu, Bao Yuan, Bo Bai, Xin Tong, Luke A. O’Dell, Dong Wang, Lingxue Kong and Guang Wang

Membranes 2021, 11(11), 842; https://doi.org/10.3390/membranes11110842 - 29 Oct 2021

Viewed by 1642

Abstract

Hexagonal lyotropic liquid crystals (HLLC) with uniform pore size in the range of 1~5 nm are highly sought after as promising active separation layers of thin-film composite (TFC) membranes, which have been confirmed to be efficient for water purification. The potential interaction between an amphiphile-based HLLC layer and the substrate surface, however, has not been fully explored. In this research, hydrophilic and hydrophobic microporous polyvinylidene fluoride (PVDF) substrates were chosen, respectively, to prepare TFC membranes with the active layers templated from HLLC, consisting of dodecyl trimethylammonium bromide, water, and a mixture of poly (ethylene glycol) diacrylate and 2-hydroxyethyl methacrylate. The pore size of the active layer was found to decrease by about 1.6 Å compared to that of the free-standing HLLC after polymerization, but no significant difference was observable by using either hydrophilic or hydrophobic substrates (26.9 Å vs. 27.1 Å). The water flux of the TFC membrane with the hydrophobic substrate, however, was higher than that with the hydrophilic one. A further investigation confirmed that the increase in water flux originated from a much higher porosity was due to the synergistic effect of the hydrophilic HLLC nanoporous material and the hydrophobic substrate. Full article

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

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25 pages, 7479 KiB

Open AccessArticle

New Understanding of the Difference in Filtration Performance between Anatase and Rutile TiO₂ Nanoparticles through Blending into Ultrafiltration PSF Membranes

by Iulian-Gabriel Birsan, Stefan Catalin Pintilie, Laurentia Geanina Pintilie, Andreea Liliana Lazar, Adrian Circiumaru and Stefan Balta

Membranes 2021, 11(11), 841; https://doi.org/10.3390/membranes11110841 - 29 Oct 2021

Cited by 2 | Viewed by 1894

Abstract

The blending of nanomaterials into a polymeric matrix is a method known for its ability, under certain circumstances, to lead to an improvement in membrane properties. TiO₂ nanoparticles have been used in membrane research for the last 20 years and have continuously shown promise in this field of research. Polysulfone (PSf) membranes were obtained through the phase inversion method, with different TiO₂ nanoparticle concentrations (0, 0.1, 0.5, and 1 wt.%) and two types of TiO₂ crystalline structure (anatase and rutile), via the addition of commercially available nanopowders. Research showed improvement in all studied properties. In particular, the 0.5 wt.% TiO₂ rutile membrane recorded an increase in permeability of 139.7% compared to the control membrane. In terms of overall performance, the best nanocomposite membrane demonstrated a performance index increase of 71.1% compared with the control membrane. Full article

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

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9 pages, 1452 KiB

Open AccessArticle

Ultrahigh Water Permeance of Reduced Graphene Oxide Membrane for Radioactive Liquid Waste Treatment

by Xinming Xia, Feng Zhou, Risheng Yu, Longsheng Cao and Liang Chen

Membranes 2021, 11(11), 809; https://doi.org/10.3390/membranes11110809 - 24 Oct 2021

Cited by 4 | Viewed by 2241

Abstract

Membrane methods exhibit great potential for application in radioactive liquid waste treatment. In this work, we prepared a reduced graphene oxide using the amino-hydrothermal method (AH-rGO) that exhibited effective rejection rates of 99.9% for CoCl₂, ZnCl₂, NiCl₂, and radionuclide ⁶⁰Co solutions with an ultrahigh water permeance of >71.9 L m⁻² h⁻¹ bar⁻¹. The thickness of the AH-rGO membranes affects the water permeance, as the membrane with a thickness of ≈250 nm has the highest water permeance of up to 125.1 L m⁻² h⁻¹ bar⁻¹ with the corresponding rejection rate of 86.8%. Importantly, this is the most permeable membrane with a satisfactory level of the rejection rate for typical radioactive ions of Co²⁺, Zn²⁺, and Ni²⁺. Moreover, the AH-rGO membranes presented excellent stability. These findings demonstrate the potential of reduced graphene oxide (rGO) membranes for radioactive liquid waste treatment. Full article

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

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17 pages, 5790 KiB

Open AccessEditor’s ChoiceArticle

A Facile Method to Control Pore Structure of PVDF/SiO₂ Composite Membranes for Efficient Oil/Water Purification

by Qianqian Xu, Yuchao Chen, Tonghu Xiao and Xing Yang

Membranes 2021, 11(11), 803; https://doi.org/10.3390/membranes11110803 - 22 Oct 2021

Cited by 11 | Viewed by 2415

Abstract

The use of poly(vinylidene fluoride) (PVDF) microfiltration (MF) membranes to purify oily water has received much attention. However, it is challenging to obtain high-performance PVDF microfiltration membranes due to severe surface fouling and rapid decline of permeability. This study explored a new approach to fabricate high-performance PVDF/silica (SiO₂) composite membrane via the use of a polymer solution featuring lower critical solution temperature (LCST) characteristics and the non-solvent thermally induced phase separation method (NTIPS). Coupling with morphological observations, the membrane formation kinetics were analyzed in depth to understand the synergistic effect between the LCST solution properties and fabrication conditions in NTIPS. Utilizing such a synergistic effect, the transition from finger-like macrovoid pores to bi-continuous highly connected pores could be flexibly tuned by increasing the PVDF concentration and the weight ratio of SiO₂/PVDF in the dope solution and by raising the coagulation temperature to above the LCST of the solution. The filtration experiments with surfactant-stabilized oil-water emulsion showed that the permeation flux of the PVDF/SiO₂ composite membranes was higher than 318 L·m⁻²·h⁻¹·bar⁻¹ and the rejection above 99.2%. It was also shown that the PVDF/SiO₂ composite membranes, especially those fabricated above the LCST, demonstrated better hydrophilicity, which resulted in significant enhancement in the anti-fouling properties for oil/water emulsion separation. Compared to the benchmark pure PVDF membrane in oily water purification, the optimal composite membrane T70 was demonstrated via the 3-cycle filtration experiments with a significantly improved flux recovery ratio (F_rr) and minimal reduced irreversible fouling (R_ir). Overall, with the developed method in this work, facile procedure to tune the membrane morphology and pore structure was demonstrated, resulting in high performance composite membranes suitable for oil/water emulsion separation. Full article

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

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15 pages, 2331 KiB

Open AccessArticle

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

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

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

Cited by 21 | Viewed by 4898

Abstract

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

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

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21 pages, 3744 KiB

Open AccessArticle

Modeling of Nanofiltration Process Using DSPM-DE Model for Purification of Amine Solution

by Asma Ghorbani, Behrouz Bayati, Enrico Drioli, Francesca Macedonio, Tavan Kikhavani and Mirko Frappa

Membranes 2021, 11(4), 230; https://doi.org/10.3390/membranes11040230 - 24 Mar 2021

Cited by 12 | Viewed by 2869

Abstract

The formation of heat stable salts (HSS) during the natural gas sweetening process by amine solvent causes many problems such as corrosion, foaming, capacity reduction, and amine loss. A modeling study was carried out for the removal of HSS ions from amine solution using nanofiltration (NF) membrane process that ensures the reuse of amine solution for gas sweetening. This model studies the physics of the nanofiltration process by adjusting and investigating pore radius, the effects of membrane charge, and other membrane characteristics. In this paper, the performance of the ternary ions was investigated during the removal process from methyl di-ethanol amine solution by the nanofiltration membrane process. Correlation between feed concentration and permeate concentration, using experimental results with mathematical correlation as C_i,p = f (C_i,f) was used in modeling. The results showed that the calculated data from the model provided a good agreement with experimental results (R² = 0.90–0.75). Also, the effect of operating conditions (including feed pressure and feed flow rate on ions rejection and recovery ratio across the flat-sheet membrane) was studied. The results showed that the recovery and rejection ratios of the NF membrane depend on the driving pressure across the membrane. While the driving pressure is affected by the feed flow conditions and feed pressure. Full article

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

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16 pages, 3975 KiB

Open AccessArticle

Infusion of Silver–Polydopamine Particles into Polyethersulfone Matrix to Improve the Membrane’s Dye Desalination Performance and Antibacterial Property

by Hazel Lynn C. Maganto, Micah Belle Marie Yap Ang, Gian Vincent C. Dizon, Alvin R. Caparanga, Ruth R. Aquino, Shu-Hsien Huang, Hui-An Tsai and Kueir-Rarn Lee

Membranes 2021, 11(3), 216; https://doi.org/10.3390/membranes11030216 - 19 Mar 2021

Cited by 8 | Viewed by 2751

Abstract

The advancement in membrane science and technology, particularly in nanofiltration applications, involves the blending of functional nanocomposites into the membranes to improve the membrane property. In this study, Ag-polydopamine (Ag-PDA) particles were synthesized through in situ PDA-mediated reduction of AgNO₃ to silver. Infusing Ag-PDA particles into polyethersulfone (PES) matrix affects the membrane property and performance. X-ray photoelectron spectroscopy (XPS) analyses confirmed the presence of Ag-PDA particles on the membrane surface. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) describe the morphology of the membranes. At an optimum concentration of Ag-PDA particles (0.3 wt % based on the concentration of PES), the modified membrane exhibited high water flux 13.33 L∙m⁻²∙h⁻¹ at 4 bar with high rejection for various dyes of >99%. The PES_Ag-PDA0.3 membrane had a pure water flux more than 5.4 times higher than that of a pristine membrane. Furthermore, in bacterial attachment using Escherichia coli, the modified membrane displayed less bacterial attachment compared with the pristine membrane. Therefore, immobilizing Ag-PDA particles into the PES matrix enhanced the membrane performance and antibacterial property. Full article

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

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13 pages, 9126 KiB

Open AccessEditor’s ChoiceArticle

Substrate-Independent, Regenerable Anti-Biofouling Coating for Polymeric Membranes

by Juan Zhang, Guang Wang, Jianhua Zhang, Zhiguang Xu, Yan Zhao, Yichao Wang, Fenghua She, Stephen Gray and Lingxue Kong

Membranes 2021, 11(3), 205; https://doi.org/10.3390/membranes11030205 - 13 Mar 2021

Cited by 4 | Viewed by 2423

Abstract

Biofouling is a common but significant issue in the membrane process as it reduces permeate flux, increases energy costs, and shortens the life span of membranes. As an effective antibacterial agent, a small amount of silver nanoparticles (AgNPs) immobilized on membrane surfaces will alleviate the membrane from biofouling. However, loading AgNPs on the membrane surface remains a challenge due to the low loading efficiency or the lack of bonding stability between AgNPs and the membrane surface. In this study, a substrate-independent method is reported to immobilize silver nanoparticles on polymeric membrane surfaces by firstly modifying the membrane surface with functional groups and then forming silver nanoparticles in situ. The obtained membranes had good anti-biofouling properties as demonstrated from disk diffusion and anti-biofouling tests. The silver nanoparticles were stably immobilized on the membrane surfaces and easily regenerated. This method is applicable to various polymeric micro-, ultra-, nano-filtration and reverse osmosis (RO) membranes. Full article

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

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17 pages, 6614 KiB

Open AccessArticle

Polydopamine-Assisted Two-Dimensional Molybdenum Disulfide (MoS₂)-Modified PES Tight Ultrafiltration Mixed-Matrix Membranes: Enhanced Dye Separation Performance

by Huali Tian, Xing Wu and Kaisong Zhang

Membranes 2021, 11(2), 96; https://doi.org/10.3390/membranes11020096 - 30 Jan 2021

Cited by 17 | Viewed by 3079

Abstract

Tight ultrafiltration (TUF) membranes with high performance have attracted more and more attention in the separation of organic molecules. To improve membrane performance, some methods such as interface polymerization have been applied. However, these approaches have complex operation procedures. In this study, a polydopamine (PDA) modified MoS₂ (MoS₂@PDA) blending polyethersulfone (PES) membrane with smaller pore size and excellent selectivity was fabricated by a simple phase inversion method. The molecular weight cut-off (MWCO) of as-prepared MoS₂@PDA mixed matrix membranes (MMMs) changes, and the effective separation of dye molecules in MoS₂@PDA MMMs with different concentrations were obtained. The addition amount of MoS₂@PDA increased from 0 to 4.5 wt %, resulting in a series of membranes with the MWCO values of 7402.29, 7007.89, 5803.58, 5589.50, 6632.77, and 6664.55 Da. The MWCO of the membrane M3 (3.0 wt %) was the lowest, the pore size was defined as 2.62 nm, and the pure water flux was 42.0 L m⁻² h⁻¹ bar⁻¹. The rejection of Chromotrope 2B (C2B), Reactive Blue 4 (RB4), and Janus Green B (JGB) in aqueous solution with different concentrations of dyes was better than that of unmodified membrane. The separation effect of M3 and M0 on JGB at different pH values was also investigated. The rejection rate of M3 to JGB was higher than M0 at different pH ranges from 3 to 11. The rejection of M3 was 98.17–99.88%. When pH was 11, the rejection of membranes decreased with the extension of separation time. Specifically, at 180 min, the rejection of M0 and M3 dropped to 77.59% and 88.61%, respectively. In addition, the membrane had a very low retention of salt ions, Nacl 1.58%, Na₂SO₄ 10.52%, MgSO₄ 4.64%, and MgCl₂ 1.55%, reflecting the potential for separating salts and dyes of MoS₂@PDA/PES MMMs. Full article

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

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12 pages, 4336 KiB

Open AccessArticle

Modifying Cellulose Acetate Mixed-Matrix Membranes for Improved Oil–Water Separation: Comparison between Sodium and Organo-Montmorillonite as Particle Additives

by Micah Belle Marie Yap Ang, Kiara Pauline O. Devanadera, Alyssa Nicole R. Duena, Zheng-Yen Luo, Yu-Hsuan Chiao, Jeremiah C. Millare, Ruth R. Aquino, Shu-Hsien Huang and Kueir-Rarn Lee

Membranes 2021, 11(2), 80; https://doi.org/10.3390/membranes11020080 - 22 Jan 2021

Cited by 28 | Viewed by 3622

Abstract

In this study, cellulose acetate (CA) mixed-matrix membranes were fabricated through the wet-phase inversion method. Two types of montmorillonite (MMT) nanoclay were embedded separately: sodium montmorillonite (Na-MMT) and organo-montmorillonite (O-MMT). Na-MMT was converted to O-MMT through ion exchange reaction using cationic surfactant (dialkyldimethyl ammonium chloride, DDAC). Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) compared the chemical structure and composition of the membranes. Embedding either Na-MMT and O-MMT did not change the crystallinity of the CA membrane, indicating that the nanoclays were dispersed in the CA matrix. Furthermore, nanoclays improved the membrane hydrophilicity. Compared with CA_Na-MMT membrane, CA_O-MMT membrane had a higher separation efficiency and antifouling property. At the optimum concentration of O-MMT in the CA matrix, the pure water flux reaches up to 524.63 ± 48.96 L∙m⁻²∙h⁻¹∙bar⁻¹ with over 95% rejection for different oil-in-water emulsion (diesel, hexane, dodecane, and food-oil). Furthermore, the modified membrane delivered an excellent antifouling property. Full article

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

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