Polymeric Membranes Research Articles

A Comprehensive Review of Hollow-Fiber Membrane Fabrication Methods across Biomedical, Biotechnological, and Environmental Domains.

This work presents methods of obtaining polymeric hollow-fiber membranes produced via the dry-wet phase inversion method that were published in renowned specialized membrane publications in the years 2010-2020. Obtaining hollow-fiber membranes, unlike flat membranes, requires the use of a special installation for their production, the most important component of which is the hollow fiber forming spinneret. This method is most often used in obtaining membranes made of polysulfone, polyethersulfone, polyurethane, cellulose acetate, and its derivatives. Many factors affect the properties of the membranes obtained. By changing the parameters of the spinning process, we change the thickness of the membranes' walls and the diameter of the hollow fibers, which causes changes in the membranes' structure and, as a consequence, changes in their transport/separation parameters. The type of bore fluid affects the porosity of the inner epidermal layer or causes its atrophy. Porogenic compounds such as polyvinylpyrrolidones and polyethylene glycols and other substances that additionally increase the membrane porosity are often added to the polymer solution. Another example is a blend of two- or multi-component membranes and dual-layer membranes that are obtained using a three-nozzle spinneret. In dual-layer membranes, one layer is the membrane scaffolding, and the other is the separation layer. Also, the temperature during the process, the humidity, and the composition of the solution in the coagulating bath have impact on the parameters of the membranes obtained.

Sustainable membrane technology for water purification—Manufacturing, recycling and environmental impacts

Water pollution has become a serious threat to our ecosystem. Water contamination due to human, commercial, and industrial activities has negatively affected the whole world. Owing to the global demanding challenges of water pollution treatments and achieving sustainability, membrane technology has gained increasing research attention. Although numerous membrane materials have focused, the sustainable water purification membranes are most effective for environmental needs. In this regard sustainable, green, and recyclable polymeric and nanocomposite membranes have been developed. Materials fulfilling sustainable environmental demands usually include wide-ranging polyesters, polyamides, polysulfones, and recyclable/biodegradable petroleum polymers plus non-toxic solvents. Consequently, water purification membranes for nanofiltration, microfiltration, reverse osmosis, ultrafiltration, and related filtration processes have been designed. Sustainable polymer membranes for water purification have been manufactured using facile techniques. The resulting membranes have been tested for desalination, dye removal, ion separation, and antibacterial processes for wastewater. Environmental sustainability studies have also pointed towards desired life cycle assessment results for these water purification membranes. Recycling of water treatment membranes have been performed by three major processes mechanical recycling, chemical recycling, or thermal recycling. Moreover, use of sustainable membranes has caused positive environmental impacts for safe waste water treatment. Importantly, worth of sustainable water purification membranes has been analyzed for the environmentally friendly water purification applications. There is vast scope of developing and investigating water purification membranes using countless sustainable polymers, materials, and nanomaterials. Hence, value of sustainable membranes has been analyzed to meet the global demands and challenges to attain future clean water and ecosystem.

All‐solid‐state Li‐ion battery: A study on the charge/discharge mechanism of an LMO‐BCD‐MgC system

AbstractThis study presents the fabrication of an all‐solid‐state lithium‐ion battery using lithium manganese oxide (LiMn2O4; LMO) as the cathode, graphite (C), and carbon‐coated magnesium (MgC) as the anode, along with a silicate‐based solid electrolyte. To assess the charge/discharge mechanism, three polymeric membranes with varying weight percentages (5%, 30%, and 50%) of magnesium silicate are produced through battery‐cloth deposition (BCD) for use as the solid electrolyte. The findings reveal that enhancing the magnesium silicate content in the solid electrolyte (particularly at 50%) results in an increased specific capacity of the battery. The MgC anode exhibits a peak capacity of approximately 780 mAh/g during the third cycle, maintaining capacity retention of 100% over 26 cycles, addressing the issues of low specific capacity and self‐discharge in the solid‐state Li‐ion battery. Nevertheless, prolonged charge/discharge testing leads to an escalation in the surface roughness and porosity of the carbon coating on the MgC anode, resulting in a decline in capacity. These results demonstrate that the LMO‐BCD‐MgC battery system proposed in this study is a secure, eco‐friendly, and cost‐effective option with potential applications in energy storage.

Memristive switching of nanofluidic diodes by ionic concentration gradients

We demonstrate that nanofluidic diodes exhibit a memristive behavior that can be controlled not only by the amplitude and frequency of the driving oscillatory signal but also by changing the relative orientations of the externally imposed ionic concentration difference with respect to the pore charge density gradient. Because ionic concentration differences, memristive properties, and nanofluidic pores are of broad interest to electrochemical technology and membrane bioelectrochemistry, this study can be a useful contribution to the field. In our case, the memristor is a polymer membrane with current rectifying conical nanopores. The electrical interaction between the mobile ions in the aqueous solution and the pore surface charges leads to rich physico-chemical phenomena, including memory effects and the neuromorphic-like potentiation of the membrane conductance following voltage pulses (spikes). The multipore membrane can be used in the design of electrochemical circuits for signal conversion and information processing in iontronic hybrid devices.

Multifactorial evaluation of an ultra-fast process for electrospinning of recycled expanded polystyrene to manufacture high-efficiency membranes for nanoparticle air filtration

The increased production of polystyrene waste has led to the need to find efficient ways to dispose of it. One possibility is the use of solid waste to produce filter media by the electrospinning technique. The aim of this work was to develop an ultra-fast electrospinning process applied to recycled polystyrene, with statistical evaluation of the influence of polymeric solution parameters (polymer concentration and percentage of DL-limonene) and process variables (flow rate, voltage, and type of support) on nanoparticle collection efficiency, air permeability, and fiber diameter. An extensive characterization of the materials and evaluation of the morphology of the fibers was also carried out. It was found that recycled expanded polystyrene could be used in electrospinning to produce polymeric membranes. The optimized condition that resulted in the highest nanoparticle collection efficiency was a polymer concentration of 13.5%, percentage of DL-limonene of 50%, voltage of 25 kV, and flow rate of 1.2 mL/h, resulting in values of 99.97 ± 0.01%, 2.6 ± 0.5 × 10−13 m2, 0.19 Pa-1, and 708 ± 176 nm for the collection efficiency of nanoparticles in the range from 6.38 to 232.9 nm, permeability, quality factor, and mean fiber diameter, respectively. All the parameters were found to influence collection efficiency and fiber diameter. The use of DL-limonene, a natural solvent, provided benefits including increased collection efficiency and decreased fiber size. In addition, the electrostatic filtration mechanism was evaluated using the presence of a copper grid as a support for the nanofibers. The findings demonstrated that an electrospinning time of only 5 min was sufficient to obtain filters with high collection efficiencies and low pressure drops, opening perspectives for the application of polystyrene waste in the development of materials with excellent characteristics for application in the area of atmospheric pollution mitigation.

Response surface methodology to optimize membrane cleaning in nanofiltration of kraft black liquor

Better understanding of membrane fouling and cleaning can help implementation of membrane filtration processes in the pulp and paper industry. The aim of this study was to optimize membrane cleaning in the nanofiltration of kraft black liquor ultrafiltered permeate for the recovery of lignin. This work wants to assess whether the cleaning process removes the main foulants; as well as the economic viability of the optimized cleaning compared to a standard cleaning in a nanofiltration membrane plant on industrial scale.The optimization of membrane cleaning was investigated using the response surface methodology. The factors studied were time, temperature, and cleaning agent (Ultrasil 110) concentration, and flux recovery was used to evaluate the success of cleaning. Experiments were performed on laboratory scale where flat-sheet polymeric membranes were fouled with kraft black liquor ultrafiltered permeate and cleaned using various combinations of the three factors.The model developed predicted a flux recovery of 88 % when cleaning was performed for 60 min with a solution of 0.8 wt% Ultrasil 110 at 40 °C. The flux recovery measured experimentally with these cleaning parameters was 80 %. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy analysis confirmed that the optimized cleaning removed the main foulants from the membrane surface. Moreover, increasing the cleaning agent concentration or the cleaning temperature did not always lead to a higher flux recovery. The techno-economic evaluation revealed that 16 % of the cleaning costs could be saved by optimizing the cleaning process.

A Shape-Restorable hierarchical polymer membrane composite system for enhanced antibacterial and antiadhesive efficiency

Intelligent shape memory polymer can be potentially used in manufacturing implantable devices that enables a benign variation of implant dimensions with the external stimuli, thus effectively lowering insertion forces and evading associated risks. However, in surgical implantation, biomaterials-associated infection has imposed a huge burden to healthcare system that urgently requires an efficacious replacement of antibiotic usages. Preventing the initial attachment and harvesting a biocidal function upon native surfaces may be deemed as a preferable strategy to tackle the issues of bacterial infection. Herein, a functionalized polylactic acid (PLA) composite membrane assembled with graphene (GE, a widely used photothermal agent) was fabricated through a blending process and then polydimethylsiloxane utilized as binders to pack hydrophobic SiO2 tightly onto polymer surface (denoted as PLA-GE/SiO2). Such an active platform exhibited a moderate shape-memory performance upon near-infrared (NIR) light stimulation, which was feasible for programmed deformation and shape recovery. Particularly stirring was that PLA-GE/SiO2 exerted a pronounced bacteria-killing effect under NIR illumination, 99.9 % of E. coli and 99.8 % of S. aureus were effectively eradicated in a lean period of 5 min. Furthermore, the obtained composite membrane manifested excellent antiadhesive properties, resulting in a bacteria-repelling efficacy of up to 99 % for both E. coli and S. aureus species. These findings demonstrated the potential value of PLA-GE/SiO2 as a shape-restorable platform in “kill&repel” integration strategy, further expanding its applications for clinical anti-infective treatment.

Ionic Conductivity Test of Chitosan Solid Electrolyte Polymer Membrane with the Addition of Ionic Liquid

Ionic Conductivity Test of Chitosan Solid Electrolyte Polymer Membrane with the Addition of Ionic Liquid

Polymeric membranes with highly homogenized nanopores for ultrafast water purification

Polymeric membranes with highly homogenized nanopores for ultrafast water purification

AFM Analysis of Polymeric Membranes Fouling

This work represents a part of a larger work, aimed at evaluating the fouling behavior of different flat polymeric membranes for low-pressure applications when placed in contact with industrial wastewater (IWW). To design and understand the operation of a membrane process it is essential to know the fouling mechanisms. Commercial PVDF and PS membranes were tested under static conditions. The reduction in membrane flux was calculated, before and after the fouling tests. Parameters such as membrane material, pore size, solids concentration, particle size, pH, temperature, flow rate, and pressure were studied to identify the fouling behavior of the membrane. The strong adhesion of organic molecules on the membrane surface develops a resistance to pore blockage which allows a significant decrease in the flow of clean water. It is important to note that membranes of the same material, PVDF, but with different pore size (0.2 and 0.5 mm), and membranes of different materials, PVDF and PS, but with the same pore size (0.2 mm) were tested to study the trend of surface fouling to predict it and/or design surface modifications of the membranes employed. A morphological analysis of the membranes was carried out to understand the fouling mechanism, the fouling times, and the nature of the block that determines the reduction of flow through the membrane itself. Roughness measurements reveal that roughness goes up to 120 minutes of immersing time in wastewater, but after 4 hours it returns to initial value but with a significant decrease of flux to water. Understanding the relationship between flux decline, morphology, and roughness role is key to preventing fouling and studying a valid method to clean the membrane.

High-performance spiro-branched polymeric membranes for sustainability applications

High-performance spiro-branched polymeric membranes for sustainability applications

Dissipative particle dynamics simulation of proposed artificial filament contraction mechanism using variable external force inspired by nature

ABSTRACT In this numerical research, the proposed mechanism of contraction of an artificial muscle filament with regard to the performance of a natural filament and the possibility of industrial production is presented using the Dissipative Particle Dynamics (DPD) method. First, an artificial myosin component has been simulated, which includes a micro-nozzle with a thin fixed two-end polymer membrane in the middle. The swelling of the limited permeable membrane from one side results from moving the DPD fluid and, consequently, the fluid force will be transferred. Also, by changing the direction of the movement of the fluid, the swelling of the polymer membrane is reversed. It has been shown that the amount of swelling is directly dependent on the amount and direction of external force implementation ( F e = ± 0.001, ± 0.003, ± 0.005 and ± 0.007) and there is a delay (almost one DPD unit) in the amount of displacement when the direction of the flow is changed due to the inertia force effect. The proposed mechanism includes six double artificial myosins, whose myosin movement causes that actin to take contraction in a wave motion considering both forward and backward movements of the limited permeable thin membrane. Also, more artificial myosins may provide smoother contraction.

Recent 10-year development on surface modification of polymeric hollow fiber membranes via surface coating approach for gas separation: a review

Recent 10-year development on surface modification of polymeric hollow fiber membranes via surface coating approach for gas separation: a review

Hyperbranched polymeric membranes for industrial water purification

This work aims at the preparation and characterization of dual-layer (DL) nano-fibrous mat (NFM) of hydrophobic and mechanical stable polyacrylonitrile (PAN) nano-fibers (NFs), as a supporter, and polyamide 6 (PA)/chitosan (Ch) NFs as a top hydrophilic coating layer.PAN and PA fibers, as residual wastes from textile processes, were collected and dissolved in their proper solvents. PAN was electro-spuned under certain conditions of electro-spinning (voltage, flow rate, and distance between spinneret and collector) to obtain PAN-NFM. Different ratios of PA/Ch composite were prepared and then electro-spun above the PAN-NFM that was previously prepared to obtain hydrophobic/hydrophilic functional dual-layer nano-fibrous membrane (DLNFM). The efficiency of the prepared DLNFM for capturing dye residues and heavy metals from wastewater was investigated.The viscosities of the prepared composite solutions were measured. The prepared dual-layer nano-fiber membranes (DLNFMs) were chemically and physically characterized by Fourier transform infrared spectroscopy, scanning electron microscope, X-ray diffraction, and thermogravimetric analyzer. The potential of the prepared mats for the adsorption of some heavy metal ions, i.e., Cu+2, Cr+3, and Pb+2 cations in addition to dyes from wastewater was evaluated. The effect of using different concentrations of PA/Ch composite as well as the thickness of the obtained DLNFM on the filtration efficiency was studied.The results of this study show the success of functional DLNFM in dye and heavy metal removal. The maximum removal efficiency of acid dyes was reached to 73.4 % and of reactive dye was approximately 61 % for PAN/PA-1.25%Ch DLNFM after 3 days at room temperature. The removal efficiency percent of heavy metal ions reached to 54 % by DLNFM. Additionally, the results showed that 0.08 mm is the ideal thickness for maximum absorption capacity. This value is correlated with the membrane's highest Ch percentage, which is (PAN/PA-1.25%Ch). Furthermore, the results demonstrate that the presence of the Ch polymer strengthened the produced bi-layered membrane to achieve the highest thermal stability when compared to the other nano-fibrous membranes (NFMs), with the breakdown temperature of the Ch functionalized dual-layer membranes (DLMs) reaching approximately 617 °C and a maximum weight loss of 60 %.

Engineering interfacial interactions for hydrogen separation enhancement in Torlon®/mixed-linker ZIF-8 mixed matrix membranes

Polymer membranes traditionally used for gas separation can be easily fabricated via a solution process; however, they have limitations in gas separation performance. Mixed matrix membrane (MMM) with dispersed high-performance filler within a polymer matrix achieves both excellent separation efficiency and productivity. In this study, we employed Torlon® (polyamide-imide), a chemically stable and commercially available polymer, as the matrix of the membranes. To enhance the separation performance through the fabrication of MMM, we utilized 2abIm-mixed-linker ZIF-8 (ML-ZIF-8) as the filler particles to improve the interfacial interaction with the Torlon® matrix. FT-IR and XPS analyses on the Torlon®/ML-ZIF-8 MMM confirmed the occurrence of interactions between the Torlon® and ML-ZIF-8. As a result, the analysis of both the DSC and stress-strain curves confirmed the effectiveness of incorporating ML-ZIF-8 into the Torlon® for improving the stability of the polymer-filler interface. This enhancement resulted in an approximately 2.7 times higher H2 permeability for the Torlon®/ML-ZIF-8 MMM compared to the pure Torlon® membrane. Furthermore, the selectivity of H2/N2 and H2/CH4 separation increased by around 11 times and 9.6 times, respectively, leading to a significant overall improvement in separation performance.

Achieving a balance between permeability and selectivity in a ZIF-8-matrix nanocomposite membrane for desalination

Hybrid metal–organic framework (MOF)-polymer membranes are promising for addressing the permeability-selectivity tradeoff in membrane applications. The key challenges for achieving high-efficiency separation performance have been identified as increasing the MOF loading while maintaining interfacial compatibility with polymeric matrices. Herein, a novel design of ZIF-8 matrix nanocomposite membrane, with ZIF-8 nanoparticles (NPs) serving as the main matrix, was prepared by functionalizing the external surface of zeolitic imidazolate framework-8 (ZIF-8) NPs with polyethyleneimine and subsequent crosslinking into the selective layer using trimesoyl chloride as a crosslinking agent via confined interfacial polymerization. The content of ZIF-8 NPs in the selective layer was up to about 70 wt%, resulting in superior permeability (＞ 43.6 LMH bar−1) for desalination due to the large number of transport channels, which was several folds as compared to most of the reported membranes. Meanwhile, a reasonably high Na2SO4 rejection (∼95.1 %) was maintained as the polyamide fragments formed during interfacial polymerization, which filled defects among the ZIF-8 NPs. Overall, such strategy paves the way for the design of efficient MOF-based membranes for balancing between permeability and selectivity in desalination.

The Effect of Polyetherimide Polymer Membrane Composition on the Performance Efficiency of Dye Sensitized Solar Cell (DSSC) Based on Natural Photosensitizer of Butterfly Pea Flowers

The Effect of Polyetherimide Polymer Membrane Composition on the Performance Efficiency of Dye Sensitized Solar Cell (DSSC) Based on Natural Photosensitizer of Butterfly Pea Flowers

Ammonia permeation and plasticization of glassy polymeric membranes

Ammonia (NH3) is a vital industrial chemical and a potential clean fuel, whose production is increasing globally. The permeation of ammonia through glassy polymeric membranes demonstrates considerable variability, due to hydrogen bonding with both the polymer and residual water. This study reveals the underlying mechanisms for ammonia permeability within membranes, which is strongly correlated with the presence of water and the polymer's chemistry. Three polymers with varying water/ammonia affinity were studied: poly (vinyl alcohol) (PVA), polysulfone (PSU), and Teflon AF 1600. Ammonia was found to readily plasticize PVA, with sorption isotherms that follow Henry's law at conditions below the nominal glass transition temperature. Residual water within the PVA membranes increased ammonia permeability by an order of magnitude greater than that observed for well-dried PVA, due to water-induced swelling. PSU, being hydrophobic, was unaffected by residual water, though ammonia permeability was clearly time-dependent with a 50 % reduction over 4 days. This was attributed to ammonia clustering within the ammonia phobic PSU, which resulted in pore-blocking. The superhydrophobic Teflon AF 1600 membrane demonstrated the same time dependent permeability behaviour, but at a much faster timescale of minutes rather than days. It is suggested that this relates to the rate of formation of ammonia clusters, which is dependent on the degree of ammonia sorption within the polymer.

Coke oven wastewater treatment using polymeric and ceramic membranes.

This research is aimed to investigate the efficacy of membrane separation technology in treating coke oven wastewater (COW). A comparative study was conducted using three types of membranes: commercial polymeric (CP) membrane, commercial ceramic (CC) membrane, and synthesized ceramic (SC) membrane. The potential of the SC membrane in COW treatment was assessed in comparison to the CC membrane, which had a molecular weight cut-off (MWCO) of 1 Kilo-Dalton. The experiments were conducted under various trans-membrane pressure (TMP) conditions ranging from 1 to 4bar. Additionally, the effect of the CP membrane on COW treatment was examined at TMP levels ranging from 5 to 25bar. The research findings revealed that the SC membrane exhibited promising results in terms of permeability and flux compared to the CC membrane. Also, a significant reduction was observed in various water parameters such as TSS decreased by 89.74%, chlorides by 8.24%, nitrogen by 10%, and hardness by 22%. Moreover, the study was carried out by implementing an anti-fouling mechanism to mitigate fouling effects on membrane performance.

Gas Permeation through V2O5 Nanoribbons‐Based Membrane

AbstractMembrane separation processes play a crucial role in gas separation applications, with the need for ongoing development to fulfill new needs for today's challenges. For this purpose, novel 2D nanomaterials are progressively showing promise over conventional polymer‐based membrane material, exhibiting excellent molecular transport properties. Beyond the 2D materials already studied in this field, this article presents the first gas separation performances of vanadium pentoxide membrane. Brand new in gas separation topic, 2D van der Waals nanoribbons of V2O5 are successfully synthesized and layered on an anodic aluminum oxide substrate. Gas permeation analysis of He, N2, and CO2 are performed on various membranes made from different quantities of the nanomaterial. Gas permeance results suggest a deviation from an expected Knudsen diffusion mechanism of the V2O5‐based membrane for He separation. The ideal selectivities of He/N2 and He/CO2 are compared to Robeson's upper bound for polymeric membranes. V2O5 membranes, prepared with the highest V2O5 quantity, exceeded the upper bound from 2008 for He/N2 and 2019 (the most recent) for He/CO2, demonstrating the interesting potential of V2O5 2D materials for gas separation.