Letteratura scientifica selezionata sul tema "Membrane d’ultrafiltration en PES/PVP"

Silver nanoparticles (NP) was successfully immobilized on polydopamine (PDA) supported polyethersulfone (PES) membrane via a redox reaction. Polyvinylpyrrolidone (PVP) was added into membrane dope solution as a pore-forming agent. Four pieces of membranes (M1, M2, M3 and M4) were fabricated with different active layer coatings to compare their morphological and performance properties. The differences between each sample were highlighted as follow: M1 (pristine PES), M2 (PES+PVP), M3 (PDA/PES+PVP) and M4 (Ag/PDA/PES+PVP). All membranes were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and contact angle analysis. The membrane performance was examined using pure water permeability (PWP) test, antibacterial test and humic acid (HA) rejection test. Pristine M1 membrane showed that PWP of 27.16 LMH/bar and HA rejection of 84 %. In this study, it was found that the addition of PVP as a pore agent into the membrane M2 increased water flux but slightly deteriorated HA rejection. Coating of PDA on M3 and immobilizing silver NP on M4 membrane surface have improved HA rejection but compromised PWP. The results showed that membrane M4 carried excellent antibacterial property and highest HA rejection among all fabricated membranes.

Membrane based separation system is considered as a promising technology to purify water, owing to its simplicity and efficiency in operation. However, the application is limited by membrane fouling, which can lead to the declination of water flux and premature failure of membrane. The fouling can be controlled through membrane surface modification by blending hydrophilic materials during the casting solution preparation. Polyethersulfone (PES) membrane is naturally hydrophobic due to lack of oxygen functional group, which limits its application in the filtration of water. Therefore, modification of PES-based membranes is required. In this work, modification of the PES membrane was carried out by incorporating carbon-based nanomaterials (graphene oxide (GO)) and a well-known organic polymer (polyvinylpyrrolidone (PVP)). The effect of each additive toward the hydrophilicity of composite PES membrane was then investigated. GO was synthesized using modified Hummers method due to its simpler and shorter process. Each additive was added during the casting solution preparation and the amount added was varied from 0.5 to 1.0 wt%. The resultant composite PES membranes were characterized using XRD, FTIR and TGA prior to hydrophilicity and pure water flux (PWF) measurement. It was observed that the additives (PVP and GO) have significantly affected the membranes hydrophilicity, resulting in lower contact angle and higher pure water flux. The highest value of PWF (230 L/m2.h) with lowest contact angle (42 °) were observed for PES-1.0GOPVP membrane due to high amount of GO and PVP. Improved PWF performance of composite PES-1.0GOPVP membrane was attributed to the better dispersibility of the PVP and GO and increased surface hydrophilicity of the modified composite membranes. This study indicated that PVP and GO are effective modifiers to enhance the performance of PES membrane

Polyethersulfone (PES)/polyacrylonitrile (PAN) membranes have been paid attention among membrane research subjects. However, very few studies are included in the literature. In our study, asymmetric ultrafiltration (UF) membranes were prepared from blends of PES/PAN with phase inversion method using water as coagulation bath. Polyvinylpyrrolidone (PVP) with Mw of 10,000 Da was used as pore former agent. N,N-dimethylformamide was used as solvent. The effects of different percentage of PVP and PES/PAN composition on morphology and water filtration properties were investigated. Membrane performances were examined using pure water and lake water filtration studies. Performances of pure water were less with the addition of PAN into the PES polymer casting solutions. However, long-term water filtration tests showed that PES/PAN blend membranes anti-fouling properties were much higher than the neat PES membranes. The contact angles of PES/PAN membranes were lower than neat PES membranes because of PAN addition in PES polymer casting solutions. Furthermore, it was found that PES/PAN blend UF membranes' dynamic mechanical analysis properties in terms of Young's modules were less than neat PES membrane because of decreasing amount of PES polymer.

In this study, a three-bore polyethersulfone (PES) hollow fiber ultrafiltration (UF) membrane with antibacterial properties was prepared by phase inversion, using PES as the membrane material, N,N-dimethylacetamide (DMAC) as solvent, polyvinylpyrrolidone (PVP) and CuCl2 as additives. The effect of CuCl2 content on the water flux and rejection was studied and the antibacterial properties of PES hollow fiber UF membrane were also investigated. The water flux results indicated that the hydrophilic properties of PES UF membranes were improved after adding CuCl2. The rejection of PVA-50000 was expected to drop slightly but remain high above 96%. The membranes showed good antibacterial activity against Escherichia coli (E. coli) after adding CuCl2 and the antibacterial rate of PES/CuCl2 UF membranes was close to 100% after running for 48 h. PES hollow fiber UF membranes with antibacterial properties were prepared through the formation of the water-soluble PVP/Cu2+ complex with spatial network structure, which have good antibacterial and hydrophilic properties. Therefore, this study could provide an effective method for membrane antifouling.

Polyurethanes (PUs) are currently considered to be biocompatible materials but limited by a low resistance to thrombus. We therefore design a heparin-like PU (HLPU) to modify polyethersulfone (PES) membranes approaching integrated antifouling and antithrombotic properties by bioinspiration of heparin structure. Poly(vinyl pyrrolidone)-HLPU (PVP-HLPU) was synthesized via reversible addition-fragmentation chain transfer polymerization of VP using PU as a macroinitiator and then sulfonated by concentrated H2SO4. FTIR and NMR results demonstrated the successful synthesis of PVP-HLPU. By incorporation of PVP-HLPU, the cross-sectional structure of PES composite membranes altered from finger-like structure to sponge-like structure resulting in tunable permeability. The increased hydrophilicity verified by water contact angles benefited both the permeability and antifouling property. As a consequence, the composite membranes showed good blood compatibility, including decreased protein adsorption, suppressed platelet adhesion, lowered thrombin-antithrombin III generation, reduced complement activation, and prolonged clotting times. Interestingly, the PVP-capped HLPU showed better blood compatibility compared to polyethyleneglycol-capped and citric acid-capped HLPUs. The results demonstrated the enhanced antifouling and antithrombotic properties of PES hemodialysis membranes by the introduction of functional HLPUs. Also, the proposed method may forward the fabrication of hemocompatible membranes via bioinspired surface design.

Polyethersulfone (PES) is a polymer popularly used to produce ultrafiltration (UF) membranes. PES is relatively hydrophobic; thus, hydrophilic ingredients are added to the membrane matrix to reduce the fouling intensity. Ingredients such as polyvinylpyrrolidone (PVP) reduce the resistance of PES to NaOH solutions. This study investigated the possibility of using PES membranes for the separation of alkaline cleaning solutions. For this purpose, self-made PES membranes and commercial ultrafiltration PES membranes (UE10—10 kDa and UE50—100 kDa) containing PVP additive were used. The membranes were soaked for 18 months in alkaline (pH = 11.3–11.5) solutions of car washing fluids. It has been found that long-term contact with these solutions caused changes in the structure of the surface layer, especially of membranes containing PVP. As a result, the separation of dextran (100–200 kDa) decreased by 30–40% for PES membranes, 30–40% for UE10 and 40–60% for UE50. Despite these changes, the separation efficiency (rejection of COD, NTU and anionic surfactants) of synthetic car wash wastewater (mixture of surfactants and hydrowax) was similar to the results obtained for pristine membranes.

Forward osmosis (FO) has become a technology with great potential for numerous applications, including water desalination. One of the critical factors in determining the FO performance is the selection of the appropriate membrane material that compatible with draw solution. In this study, commercial cellulose triacetate (CTA) and aquaporin-based membranes, as well as a fabricated PES/PVP membrane, were used, with 1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) as the thermo-responsive ionic liquid (TRIL) draw solution. The bench scale of FO system was setup upon co-currently flow rate of 60.0 mL/ min at room temperature. The 7 % PVP with 15 % PES had the best performance, with the highest water flux (Jw) (4.93 LMH), lowest reverse solute diffusion (RSD) (0.43 gMH). The fabricated membrane demonstrated a significantly higher performance compared to the commercial aquaporin-based FO membrane, with an improvement of approximately 60%.

In this study, a three-bore polyethersulfone (PES) hollow fiber ultrafiltration (UF) membrane with antibacterial properties was prepared by phase inversion, using PES as the membrane material, N,N-dimethylacetamide (DMAC) as solvent, polyvinylpyrrolidone (PVP) and AgNO3 as additives. The silver particles were detected by X-ray photoelectron spectroscopy. The effect of AgNO3 content on the antibacterial properties and separation performance was studied in detail. The membranes showed good antibacterial activity against Escherichia coli after adding AgNO3 and the antibacterial rate of PES/AgNO3 UF membrane with AgNO3 content of 1 wt% could reach 99.9% after running for 48 hours. Moreover, the bovine serum albumin solution filtration results indicated that the PES/AgNO3 membranes had a certain degree of antifouling performance. Therefore, three-bore PES/AgNO3 membranes have a potential application to reduce both bacterial and organic fouling in water treatment.

The hazardous and mutagenic properties of dye effluents discharged into water bodies have led to the development of membrane separation for water treatment. pH-sensitive membranes have been widely employed as they exhibit remarkable improvements in the permeability and separation performance of polyethersulfone (PES) membranes. In this study, the PES membranes incorporated with polyvinylpyrrolidone (PVP), pluronic F108, and polyitaconic acid (PIA) by phase inversion were fabricated and characterized. PIA at different weight percentages were introduced into the PES dope solution via blending technique. The dye removal capacity, chemical composition, and thermal stability were characterized using UV-Vis spectrometer, fourier transform infrared (FTIR), and thermogravimetric analyzer (TGA) respectively. The fabricated membranes showed excellent rejection of reactive red 120 (RR120), which is an anionic dye. The study evaluated the membrane performance of pure water permeation (PWP) along with RR120 dye rejection. M20-PPI1, with a weight percentage of PVP/Pluronic F108/PIA; 3%/1.5%/0.25%, exhibited the highest water flux of 12 L/m2h and dye rejection of 82% at pH value of 2 for RR120 dye rejection. The findings propose that M20-PPI1 is an effective pH-sensitive membrane for dye rejection.

The research used polyethersulfone (PES) as a membrane material, polyvinylpyrrolidone (PVP) k30 and polyethylene glycol 400 (PEG 400) as water-soluble additives, and dimethylacetamide (DMAc) as a solvent to prepare hollow-fiber ultrafiltration membranes through a nonsolvent-induced phase separation (NIPS) process. The hydrophilic nature of PVP-k30 and PEG caused them to accumulate on the membrane surface during phase separation. The morphology, chemical composition, surface charge, and pore size of the PES membranes were evaluated by SEM, FTIR, zeta potential, and dextran filtration experiments. The paper also investigated how different spinning solution compositions affected membrane morphology and performance. The separation efficiency of membranes with four different morphologies was tested in single-protein and double-protein mixed solutions. The protein separation effectiveness of the membrane was studied through molecular weight cutoff, zeta potential, and static protein adsorption tests. In addition, the operating pressure and pH value were adjusted to improve ultrafiltration process conditions. The PES membrane with an intact sponge-like structure showed the highest separation factor of 11, making it a prime candidate membrane for the separation of bovine serum albumin (BSA) and lysozyme (LYS). The membrane had a minimal static protein adsorption capacity of 48 mg/cm2 and had excellent anti-fouling properties. When pH = 4, the BSA retention rate was 93% and the LYS retention rate was 23%. Furthermore, it exhibited excellent stability over a pH range of 1–13, confirming its suitability for protein separation applications.

L’ultrafiltration (UF) du lait écrémé pour la standardisation de la teneur en protéines pour la fabrication des fromages est un procédé membranaire très répandu à l’échelle industrielle. Cependant, le colmatage des membranes par des protéines du lait écrémé provoque une baisse de la productivité et constitue un verrou de ce procédé.Ainsi, l’étape de nettoyage/désinfection bi-quotidienne est indispensable afin de restaurer les performances de la membrane et d’assurer la sécurité sanitaire ainsi que la qualité des produits. Elle est en général réalisée avec des détergents formulés alcalins et acides mais il est également possible d’utiliser des détergents enzymatiques formulés ayant la réputation d’être plus efficaces. Cependant, peu d’études fondamentales existent à ce sujet, ce que cette thèse se propose de contribuer à combler. L’objectif de cette thèse a été de développer de nouveaux détergents enzymatiques efficaces et compatibles avec la membrane en PES/PVP largement utilisée pour l’UF de lait écrémé. La cible du nettoyage est un dépôt de protéines. La démarche s’est appuyée sur une méthodologie d’aide à la formulation de détergents fondée sur la mesure des dépôts résiduels sur la membrane par ATR-FTIR: que ce soit les protéines, les enzymes ou les autres constituants des détergents étudiés. De multiples prototypes ont été formulés en collaboration avec la société Kersia. Leur évaluation a suivi 3 étapes: i) des tests rapides en réacteur fermé (14 cm²) pour sélectionner les détergents prometteurs selon leur efficacité d’élimination du colmatage protéique, leur rinçabilité et le respect de l’intégrité de la membrane à court termes, ii) la transposition des résultats prometteurs en condition de filtration (127 cm²) validant également la filtrabilité des détergents, iii) enfin, la validation de la compatibilité détergent/membrane sur le long terme grâce au vieillissement accéléré sous micro-onde (3 cm²), et au nettoyage d’une membrane spirale (6.8 m²) pendant 52 heures
Ultrafiltration (UF) of skim milk for standardization of the protein content for cheese making is a very common membrane process at industrial scale. However, fouling of the membranes with skim milk proteins causes a drop in productivity and constitutes a barrier to this process. Thus, the twice-daily cleaning/disinfection step is essential to restore the performance of the membrane and ensure health safety and product quality. It is generally carried out with alkaline and acidic formulated detergents, but it is also possible to use formulated enzymatic detergents which enjoy the reputation of being more effective. However, few fundamental studies exist on this subject, which this thesis aims to contribute to fill. The objective of this thesis was to develop new enzymatic detergents that are are effecient and compatible with the PES/PVP membrane widely used for skim milk UF. The target of the cleaning is a protein deposit. The approach was based on a methodology to aid the formulation of detergents based on the measurement of residual deposits on the membrane by ATR-FTIR: whether proteins, enzymes or other constituents of the detergents studied. Mutliple prototypes were formulated in collaboration with Kersia Company. Their evaluation followed 3 steps: i) rapid tests in a batch reactor (14 cm²) to select promising detergents according to their effectiveness in eliminating protein fouling, their cleanability and the integrity of the membrane in the short term, ii) transposition of promissing results under filtration conditions (127 cm²) also validating the filterability detergents, iii) finally, validation of detergent/membrane compatibility over the long term thanks to accelerated aging under microwave (3 cm²) and cleaning of the spiral wound membrane (6.8 cm²) for 52 hours

Ces travaux portent sur l'étude du vieillissement de membranes d'ultrafiltration en PES / PVP. Ils sont motivés par le constat industriel de l'endommagement des membranes au cours de leur utilisation. Il est démontré que l'hypochlorite de sodium utilisé lors des procédures de lavages sur site de production d'eau potable est le principal responsable du vieillissement des membranes. Cette dégradation chimique conduit à une oxydation radicalaire de la PVP (avec et sans rupture de chaînes), entraînant son élimination partielle de la structure de la membrane. Ce phénomène provoque une augmentation de la perméabilité à l'eau pure, une diminution de la sélectivité et une altération des propriétés mécaniques de la membrane. Une relation directe entre l'évolution de l'allongement à la rupture (déterminé par essais de traction) et la quantité de PVP contenue dans les 40 premiers microns en dessous de la surface de la membrane est notamment établie. Nous mettons également en évidence la relative stabilité de la PES. L'exposition de la PES à l'hypochlorite provoque la formation de phénols ortho-substitués (sans rupture de chaînes), uniquement en présence de PVP. En plus de l'altération de la sélectivité et des propriétés mécaniques, d'un point de vue applicatif, ces modifications chimiques donnent lieu à une augmentation de la sensibilité au colmatage. Les résultats de cette étude de vieillissement accéléré en laboratoire sont supportés par l'analyse de membranes issues de modules ayant opéré durant plusieurs années sur site de production d'eau potable. En effet, les marqueurs macroscopiques et moléculaires de la dégradation présentent, dans les deux cas, les mêmes évolutions. Cependant, l'accent est mis sur l'invalidité du concept de dose, très largement utilisé pour quantifier l'avancement de la dégradation. En effet, nous démontrons que, dans la gamme de concentrations et de temps que nous avons étudié, il existe un effet prépondérant de la concentration par rapport au temps
Motivated by drinking water production plants reporting membrane failure issues, this study investigates the ageing of a commercially available PES / PVP UF hollow fiber. Proof is given that membrane degradation is mainly induced by sodium hypochlorite exposure. The effects on the PES chemical structure are limited, very low extend of chain scission occurs and the formation of an ortho-substituted phenol is observed as the main modification. Experiments show that the presence of PVP and/or PVP degradation products is a required condition for the PES oxidation to occur. On the other hand, PVP appears to be very sensitive to hypochlorite exposure. PVP radical oxidation mechanisms are identified presenting a maximal reaction rate for neutral to slightly basic pH and leading to the partial removal of the PVP degradation products from the membrane structure. Correlation of macroscopic and molecular characterizations demonstrates that PVP degradation is responsible for the membrane integrity loss (impairing selectivity and mechanical performance), while hypochlorite exposure also induces enhanced membrane / solutes interactions, leading to an accentuated fouling. The representativeness of static continuous hypochlorite exposure regarding the actual on-site membrane ageing is confirmed by the analysis of membranes extracted from an industrially operated module. Nevertheless, the hypochlorite dose parameter, widely used in the literature, is demonstrated to be inappropriate to describe the degradation rate: the hypochlorite concentration impact is shown to be dominating the exposure time impact on the degradation rate