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Abu-Zurayk, Rund, Nour Alnairat, Aya Khalaf, Abed Alqader Ibrahim e Ghada Halaweh. "Cellulose Acetate Membranes: Fouling Types and Antifouling Strategies—A Brief Review". Processes 11, n. 2 (6 febbraio 2023): 489. http://dx.doi.org/10.3390/pr11020489.
Testo completoAbstract (sommario):
Cellulose acetate (CA) is a semisynthetic, biodegradable polymer. Due to its characteristics, CA has several applications, including water membranes, filament-forming matrices, biomedical nanocomposites, household tools, and photographic films. This review deals with topics related to the CA membranes, which are prepared using different techniques, such as the phase inversion technique. CA membranes are considered very important since they can be used as microfiltration membranes (MF), ultrafiltration membranes (UF), nanofiltration membranes (NF), reverse osmosis (RO) membranes, and forward osmosis (FO) membranes. Membrane fouling results from the accumulation of materials that the membrane rejects on the surface or in the membrane’s pores, lowering the membrane’s flux and rejection rates. There are various forms of CA membrane fouling, for instance, organic, inorganic, particulate fouling, and biofouling. In this review, strategies used for CA membrane antifouling are discussed and summarized into four main techniques: feed solution pretreatment, cleaning of the membrane surface, membrane surface modification, which can be applied using either nanoparticles, polymer reactions, surface grafting, or surface topography, and surface coating.
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Branton, Daniel. "Fracture faces of frozen membranes: 50th anniversary". Molecular Biology of the Cell 27, n. 3 (febbraio 2016): 421–23. http://dx.doi.org/10.1091/mbc.e15-05-0287.
Testo completoAbstract (sommario):
In 1961, the development of an improved freeze-etching (FE) procedure to prepare rapidly frozen biological cells or tissues for electron microscopy raised two important questions. How does a frozen cell membrane fracture? What do the extensive face views of the cell’s membranes exposed by the fracture process of FE tell us about the overall structure of biological membranes? I discovered that all frozen membranes tend to split along weakly bonded lipid bilayers. Consequently, the fracture process exposes internal membrane faces rather than either of the membrane’s two external surfaces. During etching, when ice is allowed to sublime after fracturing, limited regions of the actual membrane surfaces are revealed. Examination of the fractured faces and etched surfaces provided strong evidence that biological membranes are organized as lipid bilayers with some proteins on the surface and other proteins extending through the bilayer. Membrane splitting made it possible for electron microscopy to show the relative proportion of a membrane’s area that exists in either of these two organizational modes.
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Al Harby, Nouf F., Mervette El-Batouti e Mahmoud M. Elewa. "Prospects of Polymeric Nanocomposite Membranes for Water Purification and Scalability and their Health and Environmental Impacts: A Review". Nanomaterials 12, n. 20 (17 ottobre 2022): 3637. http://dx.doi.org/10.3390/nano12203637.
Testo completoAbstract (sommario):
Water shortage is a major worldwide issue. Filtration using genuine polymeric membranes demonstrates excellent pollutant separation capabilities; however, polymeric membranes have restricted uses. Nanocomposite membranes, which are produced by integrating nanofillers into polymeric membrane matrices, may increase filtration. Carbon-based nanoparticles and metal/metal oxide nanoparticles have received the greatest attention. We evaluate the antifouling and permeability performance of nanocomposite membranes and their physical and chemical characteristics and compare nanocomposite membranes to bare membranes. Because of the antibacterial characteristics of nanoparticles and the decreased roughness of the membrane, nanocomposite membranes often have greater antifouling properties. They also have better permeability because of the increased porosity and narrower pore size distribution caused by nanofillers. The concentration of nanofillers affects membrane performance, and the appropriate concentration is determined by both the nanoparticles’ characteristics and the membrane’s composition. Higher nanofiller concentrations than the recommended value result in deficient performance owing to nanoparticle aggregation. Despite substantial studies into nanocomposite membrane manufacturing, most past efforts have been restricted to the laboratory scale, and the long-term membrane durability after nanofiller leakage has not been thoroughly examined.
4
Ramalho, Maria João, Stéphanie Andrade, Joana Angélica Loureiro e Maria Carmo Pereira. "Interaction of Bortezomib with Cell Membranes Regulates Its Toxicity and Resistance to Therapy". Membranes 12, n. 9 (23 agosto 2022): 823. http://dx.doi.org/10.3390/membranes12090823.
Testo completoAbstract (sommario):
Bortezomib (BTZ) is a potent proteasome inhibitor currently being used to treat multiple myeloma. However, its high toxicity and resistance to therapy severely limit the treatment outcomes. Drug–membrane interactions have a crucial role in drugs’ behavior in vivo, affecting their bioavailability and pharmacological activity. Additionally, drugs’ toxicity often occurs due to their effects on the cell membranes. Therefore, studying BTZ’s interactions with cell membranes may explain the limitations of its therapy. Due to the cell membranes’ complexity, lipid vesicles were proposed here as biomembrane models, focusing on the membrane’s main constituents. Two models with distinct composition and complexity were used, one composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and the other containing DMPC, cholesterol (Chol), and sphingomyelin (SM). BTZ’s interactions with the models were evaluated regarding the drugs’ lipophilicity, preferential location, and effects on the membrane’s physical state. The studies were conducted at different pH values (7.4 and 6.5) to mimic the normal blood circulation and the intestinal environment, respectively. BTZ revealed a high affinity for the membranes, which proved to be dependent on the drug-ionization state and the membrane complexity. Furthermore, BTZ’s interactions with the cell membranes was proven to induce changes in the membrane fluidity. This may be associated with its resistance to therapy, since the activity of efflux transmembrane proteins is dependent on the membrane’s fluidity.
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Romero, Virginia, Lourdes Gelde e Juana Benavente. "Electrochemical Characterization of Charged Membranes from Different Materials and Structures via Membrane Potential Analysis". Membranes 13, n. 8 (17 agosto 2023): 739. http://dx.doi.org/10.3390/membranes13080739.
Testo completoAbstract (sommario):
Electrochemical characterization of positively and negatively charged membranes is performed by analyzing membrane potential values on the basis of the Teorell–Meyer–Sievers (TMS) model. This analysis allows the separate estimation of Donnan (interfacial effects) and diffusion (differences in ions transport through the membrane) contributions, and it permits the evaluation of the membrane’s effective fixed charge concentration and the transport number of the ions in the membrane. Typical ion-exchange commercial membranes (AMX, Ionics or Nafion) are analyzed, though other experimental and commercial membranes, which are derived from different materials and have diverse structures (dense, swollen or nanoporous structures), are also considered. Moreover, for some membranes, changes associated with different modifications and other effects (concentration gradient or level, solution stirring, etc.) are also analyzed.
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Hong, Sun, Song Hua e Lu Yan. "Preparation and Characterization of Al2O3/TiO2/PVDF Polymer Composites Ultrafiltration Membrane". Applied Mechanics and Materials 253-255 (dicembre 2012): 865–70. http://dx.doi.org/10.4028/www.scientific.net/amm.253-255.865.
Testo completoAbstract (sommario):
The polymer polyvinylidene fluoride (PVDF) membranes were modified by blending with nanometer particles to improve its hydrophilic property and anti-fouling performances in the process of waste water treatment. The organic macromolecule composite ultrafiltration (UF) membranes modified by the inorganic nanometer TiO2 and Al2O3 were prepared by a phase inversion process. The composite membranes performances, such as water flux, mechanical strength, water contact angle, retention rate, pores size and pores size distribution, were compared to those of organic membranes. The surface and sectional structures of membranes were observed by scanning electron microscope (SEM). The experimental results show that the composite membrane water fluxes increases 79.5% than that of organic membrane with 3% nanometer particles addition and the proportion of TiO2 and Al2O3 is 1:1. The composite membrane average pore size is larger than that of organic membrane and the pore size distribution is more uniform. The composite UF membrane has not only maintained PVDF membrane’s favorable performances but also improved its permeation performance, intensity, hydrophilic and anti-fouling performances.
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Efome, Johnson E., Fan Yang, Dipak Rana, Takeshi Matsuura e Christopher Lan. "Functionalized PVDF Nanofiber Membranes for Desalination by Direct Contact Membrane Distillation". International Journal of Materials Science and Engineering 6, n. 2 (giugno 2018): 67–71. http://dx.doi.org/10.17706/ijmse.2018.6.2.67-71.
Testo completo
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Alshahrani, Ahmed A., Abeer A. El-Habeeb, Arwa A. Almutairi, Dimah A. Almuaither, Sara A. Abudajeen, Hassan M. A. Hassan e Ibrahim Hotan Alsohaimi. "Preparation, Characterization and Evaluation of Polyamide-Reduced Graphene Oxide as Selective Membranes for Water Purification". Journal of Composites Science 8, n. 1 (10 gennaio 2024): 24. http://dx.doi.org/10.3390/jcs8010024.
Testo completoAbstract (sommario):
Amidst the ongoing advancements in membrane technology, a leading method has come to the forefront. Recent research has emphasized the substantial influence of surface attributes in augmenting the effectiveness of thin-film membranes in water treatments. These studies reveal how surface properties play a crucial role in optimizing the performance of these membranes, further establishing their prominence in the field of membrane technology. This recognition stems from the precise engineering of surfaces, ensuring they meet the demanding requirements of advanced separation processes. This study utilizes polyamide as a discerning layer, applied atop a polysulfone support sheet through interfacial polymerization (IP) for membrane fabrication. The amounts in the various membranes were created to vary. The membrane’s permeability to water with significant salt rejection was enhanced, which improved its effectiveness. The polyamide (PA) membrane comprising graphene oxide (rGO, 0.015%) had a water permeability of 48.90 L/m2 h at 22 bar, which was much higher than the mean permeability of polyamide membranes (25.0 L/m2 h at 22 bar). On the other hand, the PA–rGO/CHIT membranes exhibited the lowest water permeability due to their decreased surface roughness. However, the membranes’ effectiveness in rejecting salts ranged from 80% to 95% for PA–rGO and PA–rGO/CHIT membranes.
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Junoh, Hazlina, Juhana Jaafar, Nik Abdul Hadi Md Nordin, Ahmad Fauzi Ismail, Mohd Hafiz Dzarfan Othman, Mukhlis A. Rahman, Farhana Aziz e Norhaniza Yusof. "Performance of Polymer Electrolyte Membrane for Direct Methanol Fuel Cell Application: Perspective on Morphological Structure". Membranes 10, n. 3 (25 febbraio 2020): 34. http://dx.doi.org/10.3390/membranes10030034.
Testo completoAbstract (sommario):
Membrane morphology plays a great role in determining the performance of polymer electrolyte membranes (PEMs), especially for direct methanol fuel cell (DMFC) applications. Membrane morphology can be divided into two types, which are dense and porous structures. Membrane fabrication methods have different configurations, including dense, thin and thick, layered, sandwiched and pore-filling membranes. All these types of membranes possess the same densely packed structural morphology, which limits the transportation of protons, even at a low methanol crossover. This paper summarizes our work on the development of PEMs with various structures and architecture that can affect the membrane’s performance, in terms of microstructures and morphologies, for potential applications in DMFCs. An understanding of the transport behavior of protons and methanol within the pores’ limits could give some perspective in the delivery of new porous electrolyte membranes for DMFC applications.
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Yeszhanov, A. B. "HYDROPHOBIZATION OF PET TRACK-ETCHED MEMBRANES FOR DIRECT CONTACT MEMBRANE DISTILLATION OF LIQUID RADIOACTIVE WASTES". Eurasian Physical Technical Journal 17, n. 2 (24 dicembre 2020): 45–54. http://dx.doi.org/10.31489/2020no2/45-54.
Testo completoAbstract (sommario):
This article provides the results of liquid low-level radioactive wastes treatment by direct contact membrane distillation using polyethylene terephthalate hydrophobic track-etched membranes. The hydrophobization of track-etched membranes was carried out by UV-induced graft polymerization of triethoxyvinylsilane with styrene and coating with fluorine-containing silanes. Hydrophobic membranes were investigated by scanning electron microscope, Fourier-transform infrared spectroscopy, contact anglemeasurements, and liquid entry pressure analysis. Prepared membranes were tested in treatment of liquid low-level radioactive wastes by membrane distillation. The influence of pore sizes on water flux and rejection degree was studied. Rejection degree was evaluated by conductometry and atomic emission method. Decontamination factors evaluated by gamma-ray spectroscopy for 60Co, 137Cs, and 241Am are 85.4, 1900 and 5.4 for membranes modified with polystyrene and triethoxyvinylsilanewith pore diameters of 142 nm; 85.0, 1462 and 4 for membranes modified with perfluorododecyltrichlorosilanewith pore diameters of 150 nm respectively.
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Alnoor, Omer, Tahar Laoui, Ahmed Ibrahim, Feras Kafiah, Ghaith Nadhreen, Sultan Akhtar e Zafarullah Khan. "Graphene Oxide-Based Membranes for Water Purification Applications: Effect of Plasma Treatment on the Adhesion and Stability of the Synthesized Membranes". Membranes 10, n. 10 (17 ottobre 2020): 292. http://dx.doi.org/10.3390/membranes10100292.
Testo completoAbstract (sommario):
The adhesion enhancement of graphene oxide (GO) and reduced graphene oxide (rGO) layer in the underlying polyethersulfone (PES) microfiltration membrane is a crucial step towards developing a high-performance membrane for water purification applications. In the present study, we modified the surface of a PES microfiltration membrane with plasma treatment (PT) carried out at different times (2, 10, and 20 min). We studied the effect of PT on the adhesion, stability, and performance of the synthesized GO/rGO-PES membranes. The membranes’ surface morphology and chemistry were characterized using atomic force microscopy, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. The membrane performance was evaluated by conducting a diffusion test for potassium chloride (KCl) ions through the synthesized membranes. The results revealed that the 2 min PT enhanced the adhesion and stability of the deposited GO/rGO layer when compared to the other plasma-treated membranes. This was associated with an increase in the KCl ion rejection from ~27% to 57%. Surface morphology analysis at a high magnification was performed for the synthesized membranes before and after the diffusion test. Although the membrane’s rejection was improved, the analysis revealed that the GO layers suffered from micro/nano cracks, which negatively affected the membrane’s overall performance. The use of the rGO layer, however, helped in minimizing the GO cracks and enhanced the KCl ion rejection to approximately 94%. Upon increasing the number of rGO deposition cycles from three to five, the performance of the developed rGO-PES membrane was further improved, as confirmed by the increase in its ion rejection to ~99%.
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Alterary, Seham S., Raya M. Alyabes, Ahmed A. Alshahrani e Monirah A. Al-Alshaikh. "Unfunctionalized and Functionalized Multiwalled Carbon Nanotubes/Polyamide Nanocomposites as Selective-Layer Polysulfone Membranes". Polymers 14, n. 8 (11 aprile 2022): 1544. http://dx.doi.org/10.3390/polym14081544.
Testo completoAbstract (sommario):
Nowadays, reverse osmosis is the most widely utilized strategy in membrane technology due to its continuous improvement. Recent studies have highlighted the importance of the surface characteristics of support layers in thin-film membranes to improve their reverse osmosis performance. In this study, interfacial polymerization was used to generate the membranes by employing polyamide as a selective layer on top of the polysulfone supporting sheet. Different membranes, varying in terms of the concentrations of unfunctionalized and functionalized multiwalled carbon nanotubes (MWCNTs), as well as ethanol, have been fabricated. The efficiency of the membrane has been increased by increasing its permeability towards water with high salt rejection. Different characterization techniques were applied to examine all of the fabricated membranes. PA-EtOH 30% (v/v), as a selective layer on polysulfone sheets to enhance the membrane’s salt rejection, was shown to be the most efficient of the suggested membranes, improving the membrane’s salt rejection. The water permeability of the polyamide membrane with EtOH 30% (v/v) was 56.18 L/m2 h bar, which was more than twice the average permeability of the polyamide membrane (23.63 L/m2 h bar). The salt rejection was also improved (from 97.73% for NaCl to 99.29% and from 97.39% for MgSO4 to 99.62% in the same condition). The PA-MWCNTs 0.15% membrane, on the other hand, had a reduced surface roughness, higher hydrophobicity, and higher water contact angle readings, according to SEM. These characteristics led to the lowest salt rejection, resulting from the hydrophobic nature of MWCNTs.
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Acarer, Seren, İnci Pir, Mertol Tüfekci, Tuğba Erkoç, Vehbi Öztekin, Can Dikicioğlu, Güler Türkoğlu Demirkol et al. "Characterisation and Mechanical Modelling of Polyacrylonitrile-Based Nanocomposite Membranes Reinforced with Silica Nanoparticles". Nanomaterials 12, n. 21 (23 ottobre 2022): 3721. http://dx.doi.org/10.3390/nano12213721.
Testo completoAbstract (sommario):
In this study, neat polyacrylonitrile (PAN) and fumed silica (FS)-doped PAN membranes (0.1, 0.5 and 1 wt% doped PAN/FS) are prepared using the phase inversion method and are characterised extensively. According to the Fourier Transform Infrared (FTIR) spectroscopy analysis, the addition of FS to the neat PAN membrane and the added amount changed the stresses in the membrane structure. The Scanning Electron Microscope (SEM) results show that the addition of FS increased the porosity of the membrane. The water content of all fabricated membranes varied between 50% and 88.8%, their porosity ranged between 62.1% and 90%, and the average pore size ranged between 20.1 and 21.8 nm. While the neat PAN membrane’s pure water flux is 299.8 L/m2 h, it increased by 26% with the addition of 0.5 wt% FS. Furthermore, thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques are used to investigate the membranes’ thermal properties. Finally, the mechanical characterisation of manufactured membranes is performed experimentally with tensile testing under dry and wet conditions. To be able to provide further explanation to the explored mechanics of the membranes, numerical methods, namely the finite element method and Mori–Tanaka mean-field homogenisation are performed. The mechanical characterisation results show that FS reinforcement increases the membrane rigidity and wet membranes exhibit more compliant behaviour compared to dry membranes.
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Prihandana, Gunawan Setia, Sayed Sulthan Maulana, Rahmat Santoso Soedirdjo, Venni Tanujaya, Desak Made Adya Pramesti, Tutik Sriani, Mohd Fadzil Jamaludin, Farazila Yusof e Muslim Mahardika. "Preparation and Characterization of Polyethersulfone/Activated Carbon Composite Membranes for Water Filtration". Membranes 13, n. 12 (12 dicembre 2023): 906. http://dx.doi.org/10.3390/membranes13120906.
Testo completoAbstract (sommario):
Ultrafiltration membrane technology holds promise for wastewater treatment, but its widespread application is hindered by fouling and flux reduction issues. One effective strategy for enhancing ultrafiltration membranes involves incorporating activated carbon powder. In this study, composite polyethersulfone (PES) ultrafiltration membranes were fabricated to include activated carbon powder concentrations between 0 and 1.5 wt.%, with carbon size fixed at 200 mesh. The ultrafiltration membranes were evaluated in terms of membrane morphology, hydrophilicity, pure water flux, equilibrium water content, porosity, average pore size, protein separation, and E-coli bacteria removal. It was found that the addition of activated carbon to PES membranes resulted in improvements in some key properties. By incorporating activated carbon powder, the hydrophilicity of PES membranes was enhanced, lowering the contact angle from 60° to 47.3° for composite membranes (1.0 wt.% of activated carbon) compared to the pristine PES membrane. Water flux tests showed that the 1.0 wt.% composite membrane yielded the highest flux, with an improvement of nearly double the initial value at 2 bar, without compromising bovine serum albumin rejection or bacterial removal capabilities. This study also found that the inclusion of activated carbon had a minor impact on the membrane’s porosity and equilibrium water content. Overall, these insights will be beneficial in determining the optimal concentration of activated carbon powder for PES ultrafiltration membranes.
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Prihandana, Gunawan Setia, Muslim Mahardika, Budi Arifvianto, Ario Sunar Baskoro, Yudan Whulanza, Tutik Sriani e Farazila Yusof. "Performance Investigation of PSF-nAC Composite Ultrafiltration Membrane for Protein Separation". Polymers 16, n. 18 (20 settembre 2024): 2654. http://dx.doi.org/10.3390/polym16182654.
Testo completoAbstract (sommario):
As a promising wastewater treatment technology, ultrafiltration membranes face challenges related to fouling and flux reduction. To enhance these membranes, various strategies have been explored. Among them, the incorporation of nano-activated carbon (nAC) powder has emerged as an effective method. In this study, composite polysulfone (PSF) ultrafiltration membranes were fabricated using nAC powder at concentrations ranging from 0 to 8 wt.%. These membranes underwent comprehensive investigation, including assessments of membrane morphology, hydrophilicity, pure water flux, equilibrium water content, porosity, average pore size, and protein separation. The addition of activated carbon improved several desirable properties. Specifically, the hydrophilicity of the PSF membranes was enhanced, with the contact angle reduced from 69° to 58° for 8 wt.% of nAC composite membranes compared to the pristine PSF membrane. Furthermore, the water flux test revealed that 6 wt.% activated carbon-based membranes exhibited the highest flux, with a nearly 3 times improvement at 2 bar. Importantly, this enhancement did not compromise the protein rejection. Additionally, the introduction of nAC had a significant effect on the membrane’s pore size by improving lysozyme rejection up to 40%. Overall, these findings will guide the selection of the optimal concentration of nAC for PSF ultrafiltration membranes.
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Rabajczyk, Anna, Maria Zielecka, Krzysztof Cygańczuk, Łukasz Pastuszka e Leszek Jurecki. "Nanometals-Containing Polymeric Membranes for Purification Processes". Materials 14, n. 3 (21 gennaio 2021): 513. http://dx.doi.org/10.3390/ma14030513.
Testo completoAbstract (sommario):
A recent trend in the field of membrane research is the incorporation of nanoparticles into polymeric membranes, which could produce synergistic effects when using different types of materials. This paper discusses the effect of the introduction of different nanometals such as silver, iron, silica, aluminum, titanium, zinc, and copper and their oxides on the permeability, selectivity, hydrophilicity, conductivity, mechanical strength, thermal stability, and antiviral and antibacterial properties of polymeric membranes. The effects of nanoparticle physicochemical properties, type, size, and concentration on a membrane’s intrinsic properties such as pore morphology, porosity, pore size, hydrophilicity/hydrophobicity, membrane surface charge, and roughness are discussed, and the performance of nanocomposite membranes in terms of flux permeation, contaminant rejection, and antifouling capability are reviewed. The wide range of nanocomposite membrane applications including desalination and removal of various contaminants in water-treatment processes are discussed.
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Kartohardjono, Sutrasno, Ghofira Muna Khansa Salsabila, Azzahra Ramadhani, Irfan Purnawan e Woei Jye Lau. "Preparation of PVDF-PVP Composite Membranes for Oily Wastewater Treatment". Membranes 13, n. 6 (20 giugno 2023): 611. http://dx.doi.org/10.3390/membranes13060611.
Testo completoAbstract (sommario):
The oil and gas industry and related applications generate large quantities of oily wastewater, which can adversely affect the environment and human health if not properly handled. This study aims to prepare polyvinylidene fluoride (PVDF) membranes incorporated with polyvinylpyrrolidone (PVP) additives and utilize them to treat oily wastewater through the ultrafiltration (UF) process. Flat sheet membranes were prepared using PVDF dissolved in N,N-dimethylacetamide, followed by the addition of PVP ranging from 0.5 to 35 g. Characterization by scanning electron microscopy (SEM), water contact angle, Fourier transform infrared spectroscopy (FTIR), and mechanical strength tests were performed on the flat PVDF/PVP membranes to understand and compare the changes in the physical and chemical properties of the membranes. Prior to the UF process, oily wastewater was treated by a coagulation–flocculation process through a jar tester using polyaluminum chloride (PAC) as a coagulant. Based on the characterization of the membrane, the addition of PVP improves the physical and chemical properties of the membrane. The membrane’s pore size becomes larger, which can increase its permeability and flux. In general, the addition of PVP to the PVDF membrane can increase the porosity and decrease the water contact angle, thereby increasing the membrane’s hydrophilicity. With respect to filtration performance, the wastewater flux of the resultant membrane increases with increasing PVP content, but the rejections for TSS, turbidity, TDS, and COD are reduced.
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Sun, Xin, Hana Shiraz, Riccardo Wong, Jingtong Zhang, Jinxin Liu, Jun Lu e Na Meng. "Enhancing the Performance of PVDF/GO Ultrafiltration Membrane via Improving the Dispersion of GO with Homogeniser". Membranes 12, n. 12 (15 dicembre 2022): 1268. http://dx.doi.org/10.3390/membranes12121268.
Testo completoAbstract (sommario):
In this study, PVDF/GO-h composite membranes were synthesised using a homogeniser to improve the dispersion of GO nanosheets within the composite membrane’s structure, and then characterised and contrasted to PVDF/GO-s control samples, which were synthesised via traditional blending method-implementing a magnetic stirrer. By characterizing membrane via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), water contact angle (WCA) and membrane performance. SEM results showed that the number of the finger-like structure channels and pores in the sponge like structure of PVDF/GO-h composite membranes become more compared with PVDF/GO-s membranes. Water contact angle tests showed that the PVDF/GO-h composite membranes have lower contact angle than PVDF/GO-s control, which indicated the PVDF/GO-h composite membranes are more hydrophilic. Results also showed that composite membranes blended using homogeniser exhibited both improved water flux and rejection of target pollutants. In summary, it was shown that the performance of composite membranes could be improved significantly via homogenisation during synthesis, thus outlining the importance of further research into proper mixing.
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Christoffersen, R., S. Kim, Y. L. Yang e A. J. Jacobson. "Analytical TEM and EPMA Study of Decomposition Reactions in an Oxygen-Separation Membrane Material". Microscopy and Microanalysis 3, S2 (agosto 1997): 745–46. http://dx.doi.org/10.1017/s1431927600010618.
Testo completoAbstract (sommario):
Mixed-conducting oxides with appropriate values of electronic and ionic conductivity have the potential to be used as ceramic “membranes” for the separation of oxygen from other gases. The separation is based on oxygen transport from an O2-rich, and hence oxidizing, gas reservoir on one side of the membrane to an O2-lean, and hence reducing, take-up reservoir on the membrane's other side. The oxide Sr(Co1-xFex)O3-δ (SCFO), which has a cubic perovskite structure, is one such potential membrane material. Although the permeation flux of oxygen through SCFO membranes has been mea-sured, the microstructural evolution of SCFO membranes during permeation has been little studied in comparison to other potential membrane oxides. Several of these other systems do show segregation and/or decomposition phenomena that potentially may affect membrane properties. Here we report preliminary results of a systematic microanalytical study of SCFO membranes using scanning electron microscopy and microanalysis in an electron probe microanalyzer (EPMA), as well as transmission electron microscopy in an analytical TEM.
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Ramaiah, N., V. Raja e Ch Ramu. "Structural and Electrical Conductivity Studies of PVDF-HFP Film Filled with Tio2 and Nacl for Polymer Semiconductors". Oriental Journal Of Chemistry 37, n. 5 (30 ottobre 2021): 1102–8. http://dx.doi.org/10.13005/ojc/370513.
Testo completoAbstract (sommario):
As prospective electrolyte membranes are fabricated using a conducting copolymer of poly (vinylidene difluoride-co-hexaf luoropropy lene) (PVDF-HFP) by a solution casting method. The prepared membranes were filled with an electrical conductor (NaCl) and semiconductor (TiO2) nanopowder in this method. The assimilated membranes were analytically characterized by scanning electron microscope (SEM) for surface morphology and X-ray diffraction (XRD) for crystalline nature of the TiO2 nanopowder present in the prepared membrane. The FTIR confirms the structural analysis of the copolymer and the NaCl and TiO2 incorporation nature into the PVDF-HFP membrane. Electrochemical stability of the fabricated membrane of PVDF-HFP was performed using thermo-gravimetric analysis (TGA). The cyclic voltammetric analysis conducted the charge and discharge tests of the filled and unfilled membrane. The addition of nano TiO2 particles and NaCl to the copolymer membrane was found to reduce the PVDF-HFP membrane's porousness and improve the ion conductivity and electrolyte/electrode interfacial stability of the filled membrane.
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Gili, Bischoff, Simon, Schmidt, Kober, Görke, Bekheet e Gurlo. "Ceria-Based Dual-Phase Membranes for High-Temperature Carbon Dioxide Separation: Effect of Iron Doping and Pore Generation with MgO Template". Membranes 9, n. 9 (26 agosto 2019): 108. http://dx.doi.org/10.3390/membranes9090108.
Testo completoAbstract (sommario):
Dual-phase membranes for high-temperature carbon dioxide separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement these membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce0.8Sm0.2O2−δ (SDC) and Ce0.8Sm0.19Fe0.01O2−δ (FSDC) ceramic powders were used to form the skeleton in dual-phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane’s ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system.
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Prachiprava Pradhan, Ajit P Rathod e Suchita B Rai. "Development and Characterization of Low-cost Ceramic Membrane". Journal of Environmental Nanotechnology 13, n. 2 (1 luglio 2024): 98–102. http://dx.doi.org/10.13074/jent.2024.06-242613.
Testo completoAbstract (sommario):
Because of their better mechanical, chemical, and thermal properties, ceramic membranes are becoming more and more popular. They also have advantages over polymeric membranes. Many researchers have attempted to produce ceramic membranes by modifying their properties through various methods of production and raw materials. At present, a number of obstacles restrict ceramic membranes from being used widely, such as the expensive cost of raw materials and the high sintering temperature during synthesis. To overcome these limitations, low-cost raw materials like cenosphere and red mud were used for making ceramic membranes. Circular disk-type membranes were produced without the need of polymeric additives using a simple pressing technique. Throughout the synthesis process, the cenosphere and red mud compositions were changed to produce the composite membranes. The temperature range at which the membranes were sintered was 700 - 900 °C. The purpose of this research was to analyse the synthesized membrane through a variety of characterization techniques, such as thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM) etc. Also, each synthesized membrane's porosity has been examined and it was found that when the sintering temperature increased, the porosity decreased for a given composition. The cost of the produced membrane was found to be ₹1898.80/m2.
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Burganos, Vasilis N. "Membranes and Membrane Processes". MRS Bulletin 24, n. 3 (marzo 1999): 19–22. http://dx.doi.org/10.1557/s0883769400051861.
Testo completoAbstract (sommario):
Membrane separation science has enjoyed tremendous progress since the first synthesis of membranes almost 40 years ago, which was driven by strong technological needs and commercial expectations. As a result, the range of successful applications of membranes and membrane processes is continuously broadening. An additional change lies in the nature of membranes, which is now extended to include liquid and gaseous materials, biological or synthetic. Membranes are understood to be thin barriers between two phases through which transport can take place under the action of a driving force, typically a pressure difference and generally a chemical or electrical potential difference.An attempt at functional classification of membranes would have to include diverse categories such as gas separation, pervaporation, reverse osmosis, micro- and ultrafiltration, and biomedical separations. The dominant application of membranes is certainly the separation of mixed phases or fluids, homogeneous or heterogeneous. Separation of a mixture can be achieved if the difference in the transport coefficients of the components of interest is sufficiently large. Membranes can also be used in applications other than separation targeting: They can be employed in catalytic reactors, energy storage and conversion systems, as key components of artificial organs, as supports for electrodes, or even to control the rate of release of both useful and dangerous species.In order to meet the requirements posed by the aforementioned applications, membranes must combine several structural and functional properties.
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Böddeker, K. W. "Membranes and Membrane Processes". Journal of Membrane Science 31, n. 2-3 (maggio 1987): 343–44. http://dx.doi.org/10.1016/s0376-7388(00)82238-3.
Testo completo
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Meares, P. "Membranes and membrane processes". Polymer 28, n. 7 (giugno 1987): 1232. http://dx.doi.org/10.1016/0032-3861(87)90271-0.
Testo completo
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Nazri, Amirul Islah, Abdul Latif Ahmad e Mohd Hazwan Hussin. "Microcrystalline Cellulose-Blended Polyethersulfone Membranes for Enhanced Water Permeability and Humic Acid Removal". Membranes 11, n. 9 (27 agosto 2021): 660. http://dx.doi.org/10.3390/membranes11090660.
Testo completoAbstract (sommario):
A novel polyethersulfone (PES)/microcrystalline cellulose (MCC) composite membrane for humic acid (HA) removal in water was fabricated using the phase inversion method by blending hydrophilic MCC with intrinsically hydrophobic PES in a lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) co-solvent system. A rheological study indicated that the MCC-containing casting solutions exhibited a significant increase in viscosity, which directly influenced the composite membrane’s pore structure. Compared to the pristine PES membrane, the composite membranes have a larger surface pore size, elongated finger-like structure, and presence of sponge-like pores. The water contact angle and pure water flux of the composite membranes indicated an increase in hydrophilicity of the modified membranes. However, the permeability of the composite membranes started to decrease at 3 wt.% MCC and beyond. The natural organic matter removal experiments were performed using humic acid (HA) as the surface water pollutant. The hydrophobic HA rejection was significantly increased by the enhanced hydrophilic PES/MCC composite membrane via the hydrophobic–hydrophilic interaction and pore size exclusion. This study provides insight into the utilization of a low-cost and environmentally friendly additive to improve the hydrophilicity of PES membranes for efficient removal of HA in water.
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Safarpour, Mahdie, Shahla Hosseinpour, Mahsa Haddad Irani-nezhad, Yasin Orooji e Alireza Khataee. "Fabrication of Ti2SnC-MAX Phase Blended PES Membranes with Improved Hydrophilicity and Antifouling Properties for Oil/Water Separation". Molecules 27, n. 24 (15 dicembre 2022): 8914. http://dx.doi.org/10.3390/molecules27248914.
Testo completoAbstract (sommario):
In this research work, the Ti2SnC MAX phase (MP) was synthesized via the reactive sintering procedure. The layered and crystalline structure of this MP was verified by SEM, HRTEM, and XRD analyses. This nano-additive was used for improvement of different features of the polyethersulfone (PES) polymeric membranes. The blended membranes containing diverse quantities of the MP (0–1 wt%) were fabricated by a non-solvent-induced phase inversion method. The asymmetric structure of the membranes with small holes in the top layer and coarse finger-like holes and macro-voids in the sublayer was observed by applying SEM analysis. The improvement of the membrane’s hydrophilicity was verified via reducing the contact angle of the membranes from 63.38° to 49.77° (for bare and optimum membranes, respectively). Additionally, in the presence of 0.5 wt% MP, the pure water flux increased from 286 h to 355 L/m2 h. The average roughness of this membrane increased in comparison with the bare membrane, which shows the increase in the filtration-available area. The high separation efficiency of the oil/water emulsion (80%) with an improved flux recovery ratio of 65% was illustrated by the optimum blended membrane.
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Covaliu-Mierlă, Cristina Ileana, Oana Păunescu e Horia Iovu. "Recent Advances in Membranes Used for Nanofiltration to Remove Heavy Metals from Wastewater: A Review". Membranes 13, n. 7 (4 luglio 2023): 643. http://dx.doi.org/10.3390/membranes13070643.
Testo completoAbstract (sommario):
The presence of heavy metal ions in polluted wastewater represents a serious threat to human health, making proper disposal extremely important. The utilization of nanofiltration (NF) membranes has emerged as one of the most effective methods of heavy metal ion removal from wastewater due to their efficient operation, adaptable design, and affordability. NF membranes created from advanced materials are becoming increasingly popular due to their ability to depollute wastewater in a variety of circumstances. Tailoring the NF membrane’s properties to efficiently remove heavy metal ions from wastewater, interfacial polymerization, and grafting techniques, along with the addition of nano-fillers, have proven to be the most effective modification methods. This paper presents a review of the modification processes and NF membrane performances for the removal of heavy metals from wastewater, as well as the application of these membranes for heavy metal ion wastewater treatment. Very high treatment efficiencies, such as 99.90%, have been achieved using membranes composed of polyvinyl amine (PVAM) and glutaraldehyde (GA) for Cr3+ removal from wastewater. However, nanofiltration membranes have certain drawbacks, such as fouling of the NF membrane. Repeated cleaning of the membrane influences its lifetime.
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Bin Abid, Monis, Roswanira Abdul Wahab e Lassaad Gzara. "Membrane Distillation for Desalination and Current Advances in MD Membranes". Journal of Applied Membrane Science & Technology 27, n. 2 (24 luglio 2023): 39–88. http://dx.doi.org/10.11113/amst.v27n2.267.
Testo completoAbstract (sommario):
Desalination is a great technique to address the growing demand for water because it is essential for humans. Water treatment and desalination are two common uses for the membrane-based, non-isothermal MD (Membrane Distillation) process. It works at low pressure and temperature, and heat from waste and solar energy can meet the process's heat requirements. In MD, dissolved salts and nonvolatile contaminants are rejected as the vapors go through the membrane's pores and start condensing at the permeate side. However, because to the lack of a suitable and adaptable membrane, biofouling, wetting and water efficacy are the main problems for MD. Many researchers have recently worked on membrane composites and attempted to create effective, appealing, and unique membranes for membrane distillation. This review article talks about water shortages in the 21st century, the rise of desalination, the use of membrane distillation (MD), recent developments in membrane distillations, developments in pilot scale MD technologies, New developments in membrane fabrication and modification, the desired properties of membranes, and desalination membranes.
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Hazen, Preston, Geraline Trossi-Torres, Nawal K. Khadka, Raju Timsina e Laxman Mainali. "Binding of βL-Crystallin with Models of Animal and Human Eye Lens-Lipid Membrane". International Journal of Molecular Sciences 24, n. 17 (2 settembre 2023): 13600. http://dx.doi.org/10.3390/ijms241713600.
Testo completoAbstract (sommario):
Several discoveries show that with age and cataract formation, β-crystallin binds with the lens membrane or associates with other lens proteins, which bind with the fiber cell plasma membrane, accompanied by light scattering and cataract formation. However, how lipids (phospholipids and sphingolipids) and cholesterol (Chol) influence β-crystallin binding to the membrane is unclear. This research aims to elucidate the role of lipids and Chol in the binding of β-crystallin to the membrane and the membrane’s physical properties (mobility, order, and hydrophobicity) with β-crystallin binding. We used electron paramagnetic resonance (EPR) spin-labeling methods to investigate the binding of βL-crystallin with a model of porcine lens-lipid (MPLL), model of mouse lens-lipid (MMLL), and model of human lens-lipid (MHLL) membrane with and without Chol. Our results show that βL-crystallin binds with all of the investigated membranes in a saturation manner, and the maximum parentage of the membrane surface occupied (MMSO) by βL-crystallin and the binding affinity (Ka) of βL-crystallin to the membranes followed trends: MMSO (MPLL) > MMSO (MMLL) > MMSO (MHLL) and Ka (MHLL) > Ka (MMLL) ≈ Ka (MPLL), respectively, in which the presence of Chol reduces the MMSO and Ka for all membranes. The mobility near the headgroup regions of the membranes decreases with an increase in the binding of βL-crystallin; however, the decrease is more pronounced in the MPLL and MMLL membranes than the MHLL membrane. In the MPLL and MMLL membranes, the membranes become slightly ordered near the headgroup with an increase in βL-crystallin binding compared to the MHLL membrane. The hydrophobicity near the headgroup region of the membrane increases with βL-crystallin binding; however, the increase is more pronounced in the MPLL and MMLL membranes than the MHLL membrane, indicating that βL-crystallin binding creates a hydrophobic barrier for the passage of polar molecules, which supports the barrier hypothesis in cataract formation. However, in the presence of Chol, there is no significant increase in hydrophobicity with βL-crystallin binding, suggesting that Chol prevents the formation of a hydrophobic barrier, possibly protecting against cataract formation.
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Gayatri, Rianyza, Ahmad Noor Syimir Fizal, Erna Yuliwati, Md Sohrab Hossain, Juhana Jaafar, Muzafar Zulkifli, Wirach Taweepreda e Ahmad Naim Ahmad Yahaya. "Preparation and Characterization of PVDF–TiO2 Mixed-Matrix Membrane with PVP and PEG as Pore-Forming Agents for BSA Rejection". Nanomaterials 13, n. 6 (12 marzo 2023): 1023. http://dx.doi.org/10.3390/nano13061023.
Testo completoAbstract (sommario):
Polymeric membranes offer straightforward modification methods that make industry scaling affordable and easy; however, these materials are hydrophobic, prone to fouling, and vulnerable to extreme operating conditions. Various attempts were made in this study to fix the challenges in using polymeric membranes and create mixed-matrix membrane (MMMs) with improved properties and hydrophilicity by adding titanium dioxide (TiO2) and pore-forming agents to hydrophobic polyvinylidene fluoride (PVDF). The PVDF mixed-matrix ultrafiltration membranes in this study were made using the non-solvent phase inversion approach which is a simple and effective method for increasing the hydrophilic nature of membranes. Polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) as pore-forming chemicals were created. Pure water flux, BSA flux, and BSA rejection were calculated to evaluate the mixed-matrix membrane’s efficiency. Bovine serum albumin (BSA) solution was employed in this study to examine the protein rejection ability. Increases in hydrophilicity, viscosity, and flux in pure water and BSA solution were achieved using PVP and PEG additives. The PVDF membrane’s hydrophilicity was raised with the addition of TiO2, showing an increased contact angle to 71°. The results show that the PVDF–PVP–TiO2 membrane achieved its optimum water flux of 97 L/(m2h) while the PVDF–PEG–TiO2 membrane rejected BSA at a rate greater than 97%. The findings demonstrate that use of a support or additive improved filtration performance compared to a pristine polymeric membrane by increasing its hydrophilicity.
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Manawi, Yehia M., Kui Wang, Viktor Kochkodan, Daniel J. Johnson, Muataz A. Atieh e Marwan K. Khraisheh. "Engineering the Surface and Mechanical Properties of Water Desalination Membranes Using Ultralong Carbon Nanotubes". Membranes 8, n. 4 (13 novembre 2018): 106. http://dx.doi.org/10.3390/membranes8040106.
Testo completoAbstract (sommario):
In this work, novel polysulphone (PS) porous membranes for water desalination, incorporated with commercial and produced carbon nanotubes (CNT), were fabricated and analyzed. It was demonstrated that changing the main characteristics of CNT (e.g., loading in the dope solutions, aspect ratio, and functionality) significantly affected the membrane properties and performance including porosity, water flux, and mechanical and surface properties. The water flux of the fabricated membranes increased considerably (up to 20 times) along with the increase in CNT loading. Conversely, yield stress and Young’s modulus of the membranes dropped with the increase in the CNT loading mainly due to porosity increase. It was shown that the elongation at fracture for PS/0.25 wt. % CNT membrane was much higher than for pristine PS membrane due to enhanced compatibility of commercial CNTs with PS matrix. More pronounced effect on membrane’s mechanical properties was observed due to compatibility of CNTs with PS matrix when compared to other factors (i.e., changes in the CNT aspect ratio). The water contact angle for PS membranes incorporated with commercial CNT sharply decreased from 73° to 53° (membrane hydrophilization) for membranes with 0.1 and 1.0 wt. % of CNTs, while for the same loading of produced CNTs the water contact angles for the membrane samples increased from 66° to 72°. The obtained results show that complex interplay of various factors such as: loading of CNT in the dope solutions, aspect ratio, and functionality of CNT. These features can be used to engineer membranes with desired properties and performance.
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Steger, W. E., S. Machill, K. Herzog, R. Gerhards, I. Jussofie e H. Schator. "Infrared Spectroscopy of Site-Dependent Inhomogeneities in Conventional Flexible Polyurethane foam". Cellular Polymers 12, n. 1 (gennaio 1993): 31–45. http://dx.doi.org/10.1177/026248939301200103.
Testo completoAbstract (sommario):
An IR-microscope was used to study the cell membranes of a flexible PU foam prepared with cell dimensions up to 2.5 mm. Along the membrane's long axis IR-spectra up to 25 overlapping spots with diameters of 200 μm were measured. Varying absorbance values of the IR-signals along the membrane axis indicate variations in the membrane thickness. It was possible to correlate the absorbance values of the methyl-signals with absolute thicknesses calculated from the interference patterns observed in some spectra. In general, membranes elongated in the rise direction were thinner in the upper part. This can be explained by the influence of gravitation during the foaming process when the material is still able to flow. The detailed evaluation of the spectra shows varying concentrations of urea and urethane species across the membrane. Manually separated membranes and struts were investigated by the conventional KBr-disc technique. Statistical treatment of the data obtained shows no significant difference between both sample types. Consequently the reaction process in struts and membranes must be very similar.
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Kappes, Sebastian, Thilo Faber, Lotta Nelleßen, Tanju Yesilkaya, Udo Bock e Alf Lamprecht. "Improving Transungual Permeation Study Design by Increased Bovine Hoof Membrane Thickness and Subsequent Infection". Pharmaceutics 13, n. 12 (6 dicembre 2021): 2098. http://dx.doi.org/10.3390/pharmaceutics13122098.
Testo completoAbstract (sommario):
Ungual formulations are regularly tested using human nails or animal surrogates in Franz diffusion cell experiments. Membranes sometimes less than 100 µm thick are used, disregarding the higher physiological thickness of human nails and possible fungal infection. In this study, bovine hoof membranes, healthy or infected with Trichophyton rubrum, underwent different imaging techniques highlighting that continuous pores traversed the entire membrane and infection resulted in fungal growth, both superficial, as well as in the membrane’s matrix. These membrane characteristics resulted in substantial differences in the permeation of the antifungal model substance bifonazole, depending on the dosage forms. Increasing the thickness of healthy membranes from 100 µm to 400 µm disproportionally reduced the permeated amount of bifonazole from the liquid and semisolid forms and allowed for a more pronounced assessment of the effects by excipients, such as urea as the permeation enhancer. Similarly, an infection of 400-µm membranes drastically increased the permeated amount. Therefore, the thickness and infection statuses of the membranes in the permeation experiments were essential for a differential readout, and standardized formulation-dependent experimental setups would be highly beneficial.
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Manawi, Yehia, Viktor Kochkodan, Ahmad Ismail, Abdul Mohammad e Muataz Ali Atieh. "Performance of Acacia Gum as a Novel Additive in Thin Film Composite Polyamide RO Membranes". Membranes 9, n. 2 (15 febbraio 2019): 30. http://dx.doi.org/10.3390/membranes9020030.
Testo completoAbstract (sommario):
Novel thin film composite (TFC) polyamide (PA) membranes blended with 0.01–0.2 wt.% of Acacia gum (AG) have been prepared using the interfacial polymerization technique. The properties of the prepared membranes were evaluated using contact angle, zeta potential measurements, Raman spectroscopy, scanning electron microscopy, and surface profilometer. It was found that the use of AG as an additive to TFC PA membranes increased the membrane’s hydrophilicity (by 45%), surface charge (by 16%) as well as water flux (by 1.2-fold) compared with plain PA membrane. In addition, the prepared PA/AG membranes possessed reduced surface roughness (by 63%) and improved antifouling behavior while maintaining NaCl rejection above 96%. The TFC PA/AG membranes were tested with seawater collected from the Arabian Gulf and showed higher salt rejection and lower flux decline during filtration when compared to commercial membranes (GE Osmonics and Dow SW30HR). These findings indicate that AG can be used as an efficient additive to enhance the properties of TFC PA membranes.
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Bezanilla, Magdalena, Amy S. Gladfelter, David R. Kovar e Wei-Lih Lee. "Cytoskeletal dynamics: A view from the membrane". Journal of Cell Biology 209, n. 3 (11 maggio 2015): 329–37. http://dx.doi.org/10.1083/jcb.201502062.
Testo completoAbstract (sommario):
Many aspects of cytoskeletal assembly and dynamics can be recapitulated in vitro; yet, how the cytoskeleton integrates signals in vivo across cellular membranes is far less understood. Recent work has demonstrated that the membrane alone, or through membrane-associated proteins, can effect dynamic changes to the cytoskeleton, thereby impacting cell physiology. Having identified mechanistic links between membranes and the actin, microtubule, and septin cytoskeletons, these studies highlight the membrane’s central role in coordinating these cytoskeletal systems to carry out essential processes, such as endocytosis, spindle positioning, and cellular compartmentalization.
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Subaer, Subaer, Hamzah Fansuri, Abdul Haris, Misdayanti Misdayanti, Imam Ramadhan, Teguh Wibawa, Yulprista Putri, Harlyenda Ismayanti e Agung Setiawan. "Pervaporation Membranes for Seawater Desalination Based on Geo–rGO–TiO2 Nanocomposites: Part 2—Membranes Performances". Membranes 12, n. 11 (26 ottobre 2022): 1046. http://dx.doi.org/10.3390/membranes12111046.
Testo completoAbstract (sommario):
This is part 2 of the research on pervaporation membranes for seawater desalination based on Geo–rGO–TiO2 nanocomposite. The quality of the Geo–rGO–TiO2 pervaporation membranes (PV), as well as the suitability of the built pervaporation system, is thoroughly discussed. The four membranes described in detail in the first article were tested for their capabilities using the parameters turbidity, salinity, total suspended solids (TSS), and electrical conductivity (EC). The membranes’ flux permeate was measured as a function of temperature, and salt rejection was calculated using the electrical conductivity values of the feed and permeate. Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) techniques were used to investigate changes in the chemical composition and internal structure of the membranes after use in pervaporation systems. The morphology of the membrane’s surfaces was examined by means of scanning electron microscopy (SEM), and the elemental distribution was observed by using X-ray mapping and energy dispersive spectroscopy (EDS). The results showed that the pervaporation membrane of Geo–rGO–TiO2 (1, 3) achieved a permeate flux as high as 2.29 kg/m2·h with a salt rejection of around 91%. The results of the FTIR and XRD measurements did not show any changes in the functional group and chemical compositions of the membrane after the pervaporation process took place. Long-term pressure and temperature feed cause significant cracking in geopolymer and Geo–TiO2 (3) membranes. SEM results revealed that the surface of all membranes is leached out, and elemental distribution based on X-ray mapping and EDS observations revealed the addition of Na+ ions on the membrane surface. The study’s findings pave the way for more research and development of geopolymers as the basic material for inorganic membranes, particularly with the addition of rGO–TiO2 nanocomposites.
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Norfarhana, A. S., R. A. Ilyas, N. Ngadi, Shubham Sharma, Mohamed Mahmoud Sayed, A. S. El-Shafay e A. H. Nordin. "Natural Fiber-Reinforced Thermoplastic ENR/PVC Composites as Potential Membrane Technology in Industrial Wastewater Treatment: A Review". Polymers 14, n. 12 (15 giugno 2022): 2432. http://dx.doi.org/10.3390/polym14122432.
Testo completoAbstract (sommario):
Membrane separation processes are prevalent in industrial wastewater treatment because they are more effective than conventional methods at addressing global water issues. Consequently, the ideal membranes with high mechanical strength, thermal characteristics, flux, permeability, porosity, and solute removal capacity must be prepared to aid in the separation process for wastewater treatment. Rubber-based membranes have shown the potential for high mechanical properties in water separation processes to date. In addition, the excellent sustainable practice of natural fibers has attracted great attention from industrial players and researchers for the exploitation of polymer composite membranes to improve the balance between the environment and social and economic concerns. The incorporation of natural fiber in thermoplastic elastomer (TPE) as filler and pore former agent enhances the mechanical properties, and high separation efficiency characteristics of membrane composites are discussed. Furthermore, recent advancements in the fabrication technique of porous membranes affected the membrane’s structure, and the performance of wastewater treatment applications is reviewed.
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Liu, Chang, Yuxuan Kong, Guojiang Xia, Xiancheng Ren e Jing Zhang. "Ultraviolet Grafting of Bismuth Oxide Enhances the Photocatalytic Performance of PVDF Membrane and Improves the Problem of Membrane Fouling". Polymers 16, n. 16 (16 agosto 2024): 2322. http://dx.doi.org/10.3390/polym16162322.
Testo completoAbstract (sommario):
Photocatalytic membranes are crucial in addressing membrane fouling issues. However, the grafting amount of the catalyst on the membrane often becomes a key factor in restricting the membrane’s self-cleaning capability. To address the challenge, this manuscript proposes a method for solving membrane fouling, featuring high grafting rates of bismuth oxide (Bi2O3) and acrylic acid (AA), significant contaminant degradation capability, and reusability. A highly photocatalytic self-cleaning microfiltration membrane made of polyvinylidene fluoride bismuth oxide and acrylic acid (PVDF-g-BA) was prepared by attaching nano Bi2O3 and acrylic acid onto the polyvinylidene fluoride membrane through adsorption/deposition and UV grafting polymerization. Compared with pure membranes and pure acrylic grafted membranes (PVDF-g-AA), the modified membrane grafted with 0.5% bismuth oxide not only improves the grafting rate and filtration performance, but also has higher self-cleaning ability. Furthermore, the degradation effect of this membrane on the organic dye methyl violet 2B under visible light irradiation is very significant, with a degradation rate reaching 90% and almost complete degradation after 12 h. Finally, after repeated filtration and photocatalysis, the membrane can still significantly degrade contaminants and can be reused.
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Sosiati, Harini, Izon Suhandra, Muhammad Ramadhan, F. A. Kusuma Yuda, Yusmaniar e Yofentina Iriani. "Chitosan/PVA Nanofibrous Membranes as Air Filter Material". Materials Science Forum 1073 (31 ottobre 2022): 133–41. http://dx.doi.org/10.4028/p-qn70v1.
Testo completoAbstract (sommario):
Nanofiber membranes made of polymer materials are being extensively investigated and developed as air filter materials. This research aims to make and characterize the nanofiber membranes as filter materials capable of filtering gaseous pollutants from cigarette smoke. The electrospinning method manufactured the chitosan (CS)/PVA blend nanofiber membranes with CS/PVA ratios of (0/100, 20/80, 30/70, and 40/60 w/w) using low molecular weight (LMw) PVA and the ratios of (0/100, 10/90, 20/80, and 30/70 w/w) with high Mw (HMw) PVA. The CS concentration increased the CS-PVA solution‘s electrical conductivity and decreased the membrane‘s average fiber diameter and tensile properties. The filtration test on neat PVA and CS/LMw PVA (20/80) membranes set on the metallic substrate with a 0.08 mm hole size was conducted by varying membrane thickness (20, 35, and 45 µm). The filtration efficiency increased with the membrane thickness because membrane pores tend to be smaller, indicating that reducing the fiber diameter by adding CS increases pore size. The filtration test on CS/HMw PVA (20/80) membranes with 45 µm thickness on different substrate¢s hole sizes of (0.08, 1.19, and 1.41 mm) showed that the larger the hole size, the lower the filtration efficiency. By similar CS/PVA ratio, membrane thickness, and substrate size hole, the CS/HMw PVA's filtration efficiency (87.15%) is higher than CS/LMw PVA (85.79%). However, the CS/LMw PVA membrane showed higher tensile strength, low stiffness, and more economical air filtration material than CS/HMw PVA.
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Amrani, Mahacine. "Separating a water-propanol mixture using PDMS pervaporation membranes". Ingeniería e Investigación 28, n. 2 (1 maggio 2008): 53–58. http://dx.doi.org/10.15446/ing.investig.v28n2.14892.
Testo completoAbstract (sommario):
Recovering and purifying organic solvents during chemical and pharmaceutical synthesis has great economic and environmental importance. Water-alcohol mixture pervaporation was investigated using a pervaporation cell and hydrophobic membranes. This work studied polydimethylsiloxane (PDMS) membrane performance and hydrophobic membranes for removing propanol from aqueous mixtures. PDMS is recognised as being alcohol permselective during pervaporation. It was also observed that water was transferred through a hydrophobic membrane as water’s molecular size is smaller than that of propanol. A laboratory-scale pervaporation unit was used for studying this membrane’s separation characteristic in terms of pervaporation flux and selectivity for feeds containing up to water mass and 30°C-50°C. Total propanol/water flux was observed to vary as operating temperature increased. Although PDMS membranes presented good characteristics for separating water/propanol mixtures, the separation factor and pervaporation flow decreased as water content in the feed increased. The tested membrane was found to be very efficient for water concentrations of less than 0.3, corresponding to total flux transfer maximum.
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Borpatra Gohain, Moucham, Sachin Karki, Diksha Yadav, Archana Yadav, Neha R. Thakare, Swapnali Hazarika, Hyung Keun Lee e Pravin G. Ingole. "Development of Antifouling Thin-Film Composite/Nanocomposite Membranes for Removal of Phosphate and Malachite Green Dye". Membranes 12, n. 8 (7 agosto 2022): 768. http://dx.doi.org/10.3390/membranes12080768.
Testo completoAbstract (sommario):
Nowadays polymer-based thin film nanocomposite (TFN) membrane technologies are showing key interest to improve the separation properties. TFN membranes are well known in diverse fields but developing highly improved TFN membranes for the removal of low concentration solutions is the main challenge for the researchers. Application of functional nanomaterials, incorporated in TFN membranes provides better performance as permeance and selectivity. The polymer membrane-based separation process plays an important role in the chemical industry for the isolation of products and recovery of different important types of reactants. Due to the reduction in investment, less operating costs and safety issues membrane methods are mainly used for the separation process. Membranes do good separation of dyes and ions, yet their separation efficiency is challenged when the impurity is in low concentration. Herewith, we have developed, UiO-66-NH2 incorporated TFN membranes through interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC) for separating malachite green dye and phosphate from water in their low concentration. A comparative study between thin-film composite (TFC) and TFN has been carried out to comprehend the benefit of loading nanoparticles. To provide mechanical strength to the polyamide layer ultra-porous polysulfone support was made through phase inversion. As a result, outstanding separation values of malachite green (MG) 91.90 ± 3% rejection with 13.32 ± 0.6 Lm−2h−1 flux and phosphate 78.36 ± 3% rejection with 22.22 ± 1.1 Lm−2h−1 flux by TFN membrane were obtained. The antifouling tendency of the membranes was examined by using bovine serum albumin (BSA)-mixed feed and deionized water, the study showed a good ~84% antifouling tendency of TFN membrane with a small ~14% irreversible fouling. Membrane’s antibacterial test against E. coli. and S. aureus. also revealed that the TFN membrane possesses antibacterial activity as well. We believe that the present work is an approach to obtaining good results from the membranes under tricky conditions.
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Krausser, Johannes, Tuomas P. J. Knowles e Anđela Šarić. "Physical mechanisms of amyloid nucleation on fluid membranes". Proceedings of the National Academy of Sciences 117, n. 52 (16 dicembre 2020): 33090–98. http://dx.doi.org/10.1073/pnas.2007694117.
Testo completoAbstract (sommario):
Biological membranes can dramatically accelerate the aggregation of normally soluble protein molecules into amyloid fibrils and alter the fibril morphologies, yet the molecular mechanisms through which this accelerated nucleation takes place are not yet understood. Here, we develop a coarse-grained model to systematically explore the effect that the structural properties of the lipid membrane and the nature of protein–membrane interactions have on the nucleation rates of amyloid fibrils. We identify two physically distinct nucleation pathways—protein-rich and lipid-rich—and quantify how the membrane fluidity and protein–membrane affinity control the relative importance of those molecular pathways. We find that the membrane’s susceptibility to reshaping and being incorporated into the fibrillar aggregates is a key determinant of its ability to promote protein aggregation. We then characterize the rates and the free-energy profile associated with this heterogeneous nucleation process, in which the surface itself participates in the aggregate structure. Finally, we compare quantitatively our data to experiments on membrane-catalyzed amyloid aggregation of α-synuclein, a protein implicated in Parkinson’s disease that predominately nucleates on membranes. More generally, our results provide a framework for understanding macromolecular aggregation on lipid membranes in a broad biological and biotechnological context.
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Tomczak, Wirginia, e Marek Gryta. "The Application of Polyethersulfone Ultrafiltration Membranes for Separation of Car Wash Wastewaters: Experiments and Modelling". Membranes 13, n. 3 (10 marzo 2023): 321. http://dx.doi.org/10.3390/membranes13030321.
Testo completoAbstract (sommario):
The wastewater generated as a result of car washes is considered a new source of water. However, recovered water must meet the required quality criteria for reuse. For this purpose, the ultrafiltration (UF) process can be successfully used. The main aim of the present work was to investigate the influence of the membrane’s molecular weight cut-off (MWCO) on the UF performance in terms of the fouling phenomenon and retention degree of car wash wastewater. Moreover, for a better understanding of the fouling mechanisms, Hermia’s model was used. The experimental studies were conducted with the use of two polyethersulfone (PES) membranes (MWCO of 10 kDa and 100 kDa). It has been noted that the used membranes provided a high-quality permeate and excellent turbidity removal, up to 99%. Moreover, it has been noted that the MWCO membrane has a significant impact on the fouling mechanism. Generally, a much greater intensity of fouling for the membrane with MWCO of 100 kDa was observed. Results obtained in the present study showed that both real wastewaters and the clean solutions used for washing cars cause the fouling phenomenon. It has been proven that rinsing the membranes with water is not sufficient to recover the initial membrane’s performance. Hence, periodic chemical cleaning of the membranes was required. Fitting the experimental data to Hermia’s model allowed us to indicate that membranes with MWCO of 100 kDa are more prone to intermediate blocking. To sum up, the findings suggest that for the UF of the car wash wastewater, the use of membranes with MWCO equal to 10 kDa is recommended.
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Mahmoud, Alaa El Din, e Esraa Mostafa. "Nanofiltration Membranes for the Removal of Heavy Metals from Aqueous Solutions: Preparations and Applications". Membranes 13, n. 9 (12 settembre 2023): 789. http://dx.doi.org/10.3390/membranes13090789.
Testo completoAbstract (sommario):
Water shortages are one of the problems caused by global industrialization, with most wastewater discharged without proper treatment, leading to contamination and limited clean water supply. Therefore, it is important to identify alternative water sources because many concerns are directed toward sustainable water treatment processes. Nanofiltration membrane technology is a membrane integrated with nanoscale particle size and is a superior technique for heavy metal removal in the treatment of polluted water. The fabrication of nanofiltration membranes involves phase inversion and interfacial polymerization. This review provides a comprehensive outline of how nanoparticles can effectively enhance the fabrication, separation potential, and efficiency of NF membranes. Nanoparticles take the form of nanofillers, nanoembedded membranes, and nanocomposites to give multiple approaches to the enhancement of the NF membrane’s performance. This could significantly improve selectivity, fouling resistance, water flux, porosity, roughness, and rejection. Nanofillers can form nanoembedded membranes and thin films through various processes such as in situ polymerization, layer-by-layer assembly, blending, coating, and embedding. We discussed the operational conditions, such as pH, temperature, concentration of the feed solution, and pressure. The mitigation strategies for fouling resistance are also highlighted. Recent developments in commercial nanofiltration membranes have also been highlighted.
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Asiri, Abdullah M., Valerio Pugliese, Francesco Petrosino, Sher Bahadar Khan, Khalid Ahmad Alamry, Soliman Y. Alfifi, Hadi M. Marwani, Maha M. Alotaibi, Debolina Mukherjee e Sudip Chakraborty. "Photocatalytic Degradation of Textile Dye on Blended Cellulose Acetate Membranes". Polymers 14, n. 3 (7 febbraio 2022): 636. http://dx.doi.org/10.3390/polym14030636.
Testo completoAbstract (sommario):
This work aimed to investigate the degradation performance of natural cellulose acetate (CA) membranes filled with ZnO nanostructures. Photocatalytic degradation of reactive toxic dye methylene blue (MB) was studied as a model reaction using UV light. A CA membrane was previously casted and fabricated through the phase inversion processes and laboratory-synthesized ZnO microparticles as filler. The prepared membrane was characterized for pore size, ultrafiltration (UF) performance, porosity, morphology using scanning electron micrographs (SEM), water contact angle and catalytic degradation of MB. The prepared membrane shows a significant amount of photocatalytic oxidation under UV. The photocatalytic results under UV-light radiation in CA filled with ZnO nanoparticles (CA/ZnO) demonstrated faster and more efficient MB degradation, resulting in more than 30% of initial concentration. The results also revealed how the CA/ZnO combination effectively improves the membrane’s photocatalytic activity toward methylene blue (MB), showing that the degradation process of dye solutions to UV light is chemically and physically stable and cost-effective. This photocatalytic activity toward MB of the cellulose acetate membranes has the potential to make these membranes serious competitors for removing textile dye and other pollutants from aqueous solutions. Hence, polymer–ZnO composite membranes were considered a valuable and attractive topic in membrane technology.
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Maleš, Matko, e Larisa Zoranić. "Simulation Study of the Effect of Antimicrobial Peptide Associations on the Mechanism of Action with Bacterial and Eukaryotic Membranes". Membranes 12, n. 9 (16 settembre 2022): 891. http://dx.doi.org/10.3390/membranes12090891.
Testo completoAbstract (sommario):
Antimicrobial peptides (AMPs) can be directed to specific membranes based on differences in lipid composition. In this study, we performed atomistic and coarse-grained simulations of different numbers of the designed AMP adepantin-1 with a eukaryotic membrane, cytoplasmic Gram-positive and Gram-negative membranes, and an outer Gram-negative membrane. At the core of adepantin-1’s behavior is its amphipathic α-helical structure, which was implemented in its design. The amphipathic structure promotes rapid self-association of peptide in water or upon binding to bacterial membranes. Aggregates initially make contact with the membrane via positively charged residues, but with insertion, the hydrophobic residues are exposed to the membrane’s hydrophobic core. This adaptation alters the aggregate’s stability, causing the peptides to diffuse in the polar region of the membrane, mostly remaining as a single peptide or pairing up to form an antiparallel dimer. Thus, the aggregate’s proposed role is to aid in positioning the peptide into a favorable conformation for insertion. Simulations revealed the molecular basics of adepantin-1 binding to various membranes, and highlighted peptide aggregation as an important factor. These findings contribute to the development of novel anti-infective agents to combat the rapidly growing problem of bacterial resistance to antibiotics.
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Jun, Byung-Moon, Yeomin Yoon e Chang Min Park. "Post-Treatment of Nanofiltration Polyamide Membrane through Alkali-Catalyzed Hydrolysis to Treat Dyes in Model Wastewater". Water 11, n. 8 (9 agosto 2019): 1645. http://dx.doi.org/10.3390/w11081645.
Testo completoAbstract (sommario):
This research focused on the influence of post-treatment using alkali-catalyzed hydrolysis with a full-aromatic nanofiltration (NF) polyamide membrane and its application to the efficient removal of selected dyes. The post-treated membranes were characterized through Fourier transform infrared spectroscopy, goniometry, and zeta-potential analysis to analyze the treatment-induced changes in the intrinsic properties of the membrane. Furthermore, the changes in permeability induced by the post-treatment were evaluated via the measurement of water flux, NaCl rejection, and molecular weight cutoff (MWCO) under different pH conditions and post-treatment times. Major changes induced by the post-treatment in terms of physicochemical properties were the enhancement of permeability, hydrophilicity, and negative charge due to the hydrolysis of the membrane’s amide bonds. Four different dyes were selected as representative organic pollutants considering the MWCO of the post-treated membranes. Compared with the pristine NF membrane, membranes post-treated at pH 13.5 showed better water flux with similar rejection of the target dyes. On the basis of these results, the proposed post-treatment method for NF membranes can be applied to the removal of organic pollutants of various size.
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Wang, Jun, Andong Wang, Jiayuan Liu, Qiang Niu, Yijia Zhang, Ping Liu, Chengwen Liu, Hongshan Wang, Xiangdong Zeng e Guangyong Zeng. "Polyethyleneimine Modified Two-Dimensional GO/MXene Composite Membranes with Enhanced Mg2+/Li+ Separation Performance for Salt Lake Brine". Molecules 29, n. 18 (12 settembre 2024): 4326. http://dx.doi.org/10.3390/molecules29184326.
Testo completoAbstract (sommario):
As global demand for renewable energy and electric vehicles increases, the need for lithium has surged significantly. Extracting lithium from salt lake brine has become a cutting-edge technology in lithium resource production. In this study, two-dimensional (2D) GO/MXene composite membranes were fabricated using pressure-assisted filtration with a polyethyleneimine (PEI) coating, resulting in positively charged PEI-GO/MXene membranes. These innovative membranes, taking advantage of the synergistic effects of interlayer channel sieving and the Donnan effect, demonstrated excellent performance in Mg2+/Li+ separation with a mass ratio of 20 (Mg2+ rejection = 85.3%, Li+ rejection = 16.7%, SLi,Mg = 5.7) in simulated saline lake brine. Testing on actual salt lake brine in Tibet, China, confirmed the composite membrane’s potential for effective Mg2+/Li+ separation. In the actual brine test with high concentration, Mg2+/Li+ after membrane separation is 2.2, which indicates that the membrane can significantly reduce the concentration of Mg2+ in the brine. Additionally, the PEI-GO/MXene composite membrane demonstrated strong anti-swelling properties and effective divalent ion rejection. This research presents an innovative approach to advance the development of 2D membranes for the selective removal of Mg2+ and Li+ from salt lake brine.
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M. Kadhum, Aya, Mustafa H. Al-Furaiji e Zaidun N. Abudi. "EVALUATION OF THIN FILM COMPOSITE FORWARD OSMOSIS MEMBRANES: EFFECT OF POLYMER TYPE". Journal of Engineering and Sustainable Development 25, n. 6 (1 novembre 2021): 65–73. http://dx.doi.org/10.31272/jeasd.25.6.7.
Testo completoAbstract (sommario):
In the forward osmosis (FO) processes, the semipermeable membranes are used. These membranes are prepared from several types of polymers. In this research, the characterizations of each polymer were studied to conversance the effect of polymer type on the efficiency of the forward osmosis process. The prepared membrane’s roughness was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM) to compare the formation of the TFC polyamide selective layer on each polymer type. Also, SEM images showed the distribution of pores on the prepared membrane. Contact angle (CA) measurements explained the hydrophilic and hydrophobic properties of membrane types. Finally, Energy dispersion spectrometry (EDS) was tested to determine the type, amount, and distribution of atoms in the prepared membranes. All of these characterizations proved that the Polysulfone (PSU) polymer was the best choice in the FO process. It can be proved that by test results, the PSU membrane gave the optimal water flux and salt rejection.