Membrane Surface Characteristics Research Articles

Development of a Negatively Charged Polyether Sulfone Membrane Enriched with MIL-101(Cr)-Modified Magnetic Activated Pyrolytic Coke for Enhanced Dye Removal, Permeability, and Antifouling Properties

Developing high-performance nanofiltration membranes for effectively treating wastewater contaminated with organic pollutants has become increasingly important. Given the hazardous nature of these contaminants, proper treatment of wastewater is crucial before it is released into natural water bodies. This study synthesized a novel composite membrane by incorporating Fe3O4@APC@MIL-101(Cr) nanocomposites into a polyether sulfone (PES) matrix using a phase inversion technique. The inclusion of 0.5wt.% Fe3O4@APC@MIL-101(Cr) significantly enhanced the membrane's hydrophilicity, porosity, and surface characteristics. The optimized membrane achieved an impressive pure water flux (PWF) of 90.24L/m²h, reflecting a 400% improvement over pristine PES membranes. Moreover, it exhibited excellent rejection rates of 97.21% for crystal violet (CV) and 99.43% for methylene blue (MB), alongside a rejection efficiency of 57.73% for the anionic dye methyl orange (MO). The antifouling performance was notably improved, as evidenced by an increase in the flux recovery ratio (FRR) from 46% for bare PES membranes to 81.11% for hybrid membranes. Additionally, the effects of various salt types on the membrane's separation performance were investigated. The Fe3O4@APC@MIL-101(Cr) modified PES membranes demonstrate significant potential as effective candidates for treating wastewater contaminated with dye pollutants.

Biomimetic Dual‐Driven Heterojunction Nanomotors for Targeted Catalytic Immunotherapy of Glioblastoma

AbstractThe existence of the blood–brain barrier (BBB) and the characteristics of the immunosuppressive microenvironment in glioblastoma (GBM) present significant challenges for targeted GBM therapy. To address this, a biomimetic hybrid cell membrane‐modified dual‐driven heterojunction nanomotor (HM@MnO2‐AuNR‐SiO2) is proposed for targeted GBM treatment. These nanomotors are designed to bypass the BBB and target glioma regions by mimicking the surface characteristics of GBM and macrophage membranes. More importantly, the MnO2‐AuNR‐SiO2 heterojunction structure enables dual‐driven propulsion through near‐infrared‐II (NIR‐II) light and oxygen bubbles, allowing effective treatment at deep tumor sites. Meanwhile, the plasmonic AuNR‐MnO2 heterostructure facilitates the separation of electron–hole pairs and generates reactive oxygen species (ROS), inducing immunogenic tumor cell death under NIR‐II laser irradiation. Furthermore, MnO2 in the tumor microenvironment reacts to release Mn2+ ions, activating the cGAS‐STING pathway and enhancing antitumor immunity. In vitro and in vivo experiments demonstrate that these dual‐driven biomimetic nanomotors achieve active targeting and deep tumor infiltration, promoting M1 macrophage polarization, dendritic cell maturation, and effector T‐cell activation, thereby enhancing GBM catalysis and immunotherapy through ROS production and STING pathway activation.

An efficient approach in water desalination using high flux induced magnetic-field hydroxyl-functionalized MgFe2O4 /CA RO membranes with organic/inorganic fouling control capability

Reverse osmosis (RO) membranes are crucial for water purification and desalination, facing challenges like balancing permeate flux and rejection, dealing with membrane fouling, and chlorine resistance. This study focuses on developing new membranes using cellulose acetate (CA) polymers and magnetic nanoparticles of magnesium ferrite (MgFe2O4) and hydroxyl-functionalized magnesium ferrite (OH–MgFe2O4) through a phase inversion method, with and without the presence of a magnetic field, to address the limitations of RO membranes. This study conducted a unique experiment where magnetic nanoparticles migrated to the membrane surface and underwent phase exchange in the coagulation bath under the influence of a 2.0 T magnetic field. As a result, the magnetic nanoparticles were arranged in a specific pattern and evenly spread across the membrane surface, enhancing the membrane's surface characteristics and hydrophilic properties. Furthermore, the flux of the synthesized membranes experienced an increase when exposed to the magnetic field, while maintaining a consistently high rejection rate. An evaluation was conducted on the membranes' resistance to organic fouling from bovine serum albumin (BSA), inorganic fouling from scaling, and the combined effects of BSA and scaling. Based on the findings, the membranes showed a notable enhancement in their anti-fouling properties, particularly when exposed to a magnetic field. An assessment was conducted on the resistance to chlorine for both the standard and improved membranes. Comparing the flux and rejection of the membranes before and after chlorine exposure revealed a minor variation, suggesting the membrane's ability to resist surface damage from chlorine. Hence, through the creation of innovative MgFe2O4/CA and OH–MgFe2O4/CA membranes, the identified constraints of RO membranes were effectively addressed. One of the synthesized RO membranes, OH–MgFe2O4/CA, demonstrated superior performance in permeate flux, rejection, anti-fouling, and chlorine resistance when compared to MgFe2O4/CA membranes. Furthermore, the stability of the synthesized membranes was assessed through tensile strength testing, which confirmed the preservation of the membrane structure.

Composite Ion-Exchange Membranes with High Specific Ion Selectivity for Efficient Electro-Membrane Processes

The advancement of ion-exchange membranes (IEMs) with heightened permselectivity for specific ions is pivotal for improving electro-membrane processes. Achieving targeted ion selectivity necessitates precise control over membrane surface characteristics, including electrostatic forces, ion transport channel size, and hydrophobicity. Utilization of diverse nanostructured materials, particularly metal-organic frameworks (MOFs), offers a pathway to modify these surface properties. MOFs, known for their structural diversity, adjustable pore sizes, and customizable frameworks, are widely applied in separation, catalysis, electrochemical, and biomedical fields. This study presents novel composite membranes, enhanced with various nanostructured materials including MOFs, demonstrating improved specific ion selectivity, robust physical strength, and superior electrochemical properties compared to standard commercial membranes. Notably, these membranes exhibit augmented performance in water-splitting electrodialysis for LiOH production, attributed to enhanced proton-blocking and monovalent ion permeability. This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korea government (MEST) (NRF-2022M3C1A3081178 and NRF-2022M3H4A4097521).

Novel partially cross-linked nanoparticles graft co-polymer as pore former for polyethersulfone membranes for dyes removal

A newly developed water-soluble polymeric nano-additive termed “partially cross-linked nanoparticles graft copolymer (PCLNPG)" has been successfully synthesized and harnessed as a pore former for modifying a polyethersulfone ultrafiltration membrane for dyes removal. The PCLNPG content was varied in the PES polymeric matrix aiming to scrutinize its impact on membrane surface characteristics, morphological structure, and overall performance. Proposed interaction mechanism between methylene blue (MB), methyle orange (MO), and malachite green (MG) dyes with PES membrane was presented as well. Hydrophilicity and porosity of the novel membrane increased by 18 and 17 %, respectively, when manufactured with a 3 Wt. % PCLNPG, according to the findings. Besides this, the disclosed increased porosity, rather than the hydrophilic properties of the water-soluble PCLNPG, was the principal cause of the diminished contact angle. Meanwhile, raising the PCLNPG content in the prepared membrane made worthy shifts in its structure. A sponge-like region was materialized near the bottom surface as well. The membrane's pure water flux (PWF) synthesized with 3 Wt.% PCLNPG recorded 628 LMH, which is estimated 3.95 fold the pristine membrane. MG, MB, and MO dyes were rejected by 90.6, 96.3, and 97.87 %, respectively. These findings showed that the performance characteristics of the PES/PCLNPG membrane make it a potentially advantageous option to treat the textile wastewater.

Morphology of Neutrophils during Their Activation and NETosis: Atomic Force Microscopy Study.

Confocal microscopy and fluorescence staining of cellular structures are commonly used to study neutrophil activation and NETosis. However, they do not reveal the specific characteristics of the neutrophil membrane surface, its nanostructure, and morphology. The aim of this study was to reveal the topography and nanosurface characteristics of neutrophils during activation and NETosis using atomic force microscopy (AFM). We showed the main stages of neutrophil activation and NETosis, which include control cell spreading, cell fragment formation, fusion of nuclear segments, membrane disruption, release of neutrophil extracellular traps (NETs), and final cell disintegration. Changes in neutrophil membrane nanosurface parameters during activation and NETosis were quantified. It was shown that with increasing activation time there was a decrease in the spectral intensity of the spatial periods. Exposure to the activator A23187 resulted in an increase in the number and average size of cell fragments over time. Exposure to the activators A23187 and PMA (phorbol 12-myristate 13-acetate) caused the same pattern of cell transformation from spherical cells with segmented nuclei to disrupted cells with NET release. A23187 induced NETosis earlier than PMA, but PMA resulted in more cells with NETosis at the end of the specified time interval (180 min). In our study, we used AFM as the main research tool. Confocal laser-scanning microscopy (CLSM) images are provided for identification and detailed analysis of the phenomena studied. In this way, we exploited the advantages of both techniques.

Improving surface characteristics and operational parameters of polyvinyl chloride ultrafiltration membranes: How to manipulate the performance of thin film composite forward osmosis membranes?

The environmental and economic costs are pivotal aspects that should be considered before the commercialization of any membrane separation-based process. Particularly, realizing this goal relies entirely on the key role played by fabrication and operational parameters. Herein, we introduced a systematic investigation for constructing thin-film composite (TFC) - forward osmosis (FO) membranes for direct fertigation applications. To the best of our knowledge, PVC membrane was rarely used as a porous top surface substrate for TFC-FO membranes. The PVC substrate porous structure and polyamide (PA) active layer were manipulated by variating their concentrations and reaction time to optimize the FO membrane performance. All necessary characterization tools were employed to visualize the fabricated TFC membrane's surface characteristics. The influence of feed solution concentration, membrane orientation, flow rate, and draw solutes on the FO work was also methodically tested. Results demonstrated that the porous structure-substrate membrane host polymer content had imparted a significant role in tailoring the TFC-FO performance concerning permeability and back-solute flux. The water flux was improved by 44.3 % with decreasing of the PVC amount, whereas water flux was improved by 48.13 % with decreasing of the M-phenylenediamine monomer (MPD) content from 3 to 1 wt% at constant tri-mesoylchloride monomer (TMC) content of 0.1 wt% in IP reaction conditions of a thin film. This was gone hand in hand with optimal operational conditions harnessed for optimizing the FO process.

Polyethersulfone membrane coated with Dragon blood resin: Effect of input parameters and optimization using response surface methodology

This study investigates the effectiveness of dragon blood resin (DBR) as a hydrophilic additive to prevent fouling on membrane surfaces. The input parameters, including DBR, Fe3+, NMP concentration, and coating time were studied to understand their correlation with response variables, such as permeability, selectivity, and fouling recovery. A central composite design (CCD) to analyze the twenty-one sets of experimental designs. The selected membrane was characterized for hydrophilicity, functional group, morphology, and mechanical properties. The ANOVA result indicates that the p-value for all response models is significant, except for humic acid rejection. The study found that a higher concentration of DBR and NMP, as well as a longer coating time, result in lower permeability, greater humic acid rejection, and higher contact angle, while Fe3+ concentration does not have a significant effect. The membrane's surface characteristics did not change significantly after coating, such as chemical function and morphology, while the tensile strength decreased with increasing DBR concentration, NMP, and coating time. The membranes demonstrated good selectivity and antifouling properties, with the optimal condition being 0.223 mg/L DBR, 5 min coating time, 1.65 mg/L Fe3+, and 46.19% NMP, resulting in 30.34 L/m2.h.bar of humic acid permeability and 119.6% of fouling recovery.

High-performance nanofiltration membranes with a polyamide-polyester composite layer and a polydopamine surface layer for desalination and dye pollutant removal

Due to water shortages, people have to use wastewater, seawater and brackish groundwater. People prefer to use membrane-based technologies to produce high-quality water, because they are environmentally friendly and have higher energy efficiencies than traditional thermal methods. The desalination nanofiltration (NF) membranes developed demonstrate a trade-off between water permeabilities and selectivities. Researchers are devoted to develop desalination NF membranes with both high water permeabilities and high selectivities. Using novel strategies, we successfully constructed double-high-performance NF membranes with a polyamide-polyester composite layer and a surface layer via a facile additional two-step approach. We used both triethanolamine (TEOA) and piperazine (PIP) to react with trimesoyl chloride (TMC) to form a composite active layer and coated the self-assembled polydopamine (PDA) on the surface of the composite active layer. To our knowledge, their performances are among the topmost of developed NF membranes for desalination and dye pollutant removal. We used scanning electron microscope (SEM), atomic force microscope (AFM) and water contact angle gauge (WCA) to investigate the membrane surface characteristics. The membrane obtained via the two-step approach has a water permeability of up to 21.3 LMH/bar, while that of the control polyamide NF membrane is as low as 8.2 LMH/bar. The developed membrane owes apparently improved water permeability in addition to maintaining high selectivities. Furthermore, the coating of the self-assembled PDA can alleviate membrane fouling. We also performed molecular dynamics (MD) simulations to study why the use of TEOA in addition to PIP to react with TMC improves membrane performances and give guidances and inspirations to future researches.

An autopsy study of hollow fiber and multibore ultrafiltration membranes from a pilot-scale ultra high-recovery filtration system for surface water treatment

The organic fouling characteristics of hollow fiber ultrafiltration (HFUF) and multibore ultrafiltration (MBUF) membranes from long-term ultrafiltration (UF) membrane systems were systemically investigated in this study. The objective was to obtain insights into the fouling behavior of dissolved organic matter (DOM) in a pilot-scale ultra-high-recovery membrane filtration system (p-UHMS) used for surface water treatment. The pilot system consisted of a series of two different UF membranes (1st stage: polyvinylidene fluoride (PVDF) HFUF and 2nd stage: polyethersulfone (PES) MBUF). It was designed to feed the HFUF concentrate to the MBUF membranes to achieve ≥99.5 % total water recovery for surface water treatment, as these advances might enhance the production efficiencies of drinking water. The experimental results confirmed that hydrophobic DOM controlled the formation of HFUF membrane organic fouling, whereas hydrophilic DOM, including polysaccharide-like and protein-like matter, promoted MBUF membrane fouling. These opposing trends were attributed to the hydrophilic characteristics of the MBUF membrane surfaces (contact angle: PVDF = 90–130° and PES ≤ 80°), which reduced the hydrophobic interactions between the UF membrane surfaces and foulants. The performance declines of the MBUF membrane due to fouling layer formation was considerably severer than those of the HFUF membrane, decreasing total permeate water in the p-UHMS. Moreover, the quantity of the desorbed MBUF membrane foulants via 0.1 N NaOH was roughly 7.2 times larger than that of the desorbed HFUF membrane foulants through 0.1 N NaOH, indicating that alkaline-based cleaning agent could much more efficiently recover the performance of the fouled MBUF membranes. Hence, adequate cleaning strategies using alkaline-based agent for the MBUF membrane appeared to be essential for preventing the performance deterioration of the p-UHMS.

Facile optimization of grafted chain length on antifouling properties based on hyperbranched polyglycerol

Surface-grafted polymer brushes for enhancing biofouling resistance are determined by both the grafting density and chain length of brush on the antifouling membrane surfaces. However, the relations and internal regularities between the arrangement of polymer brush and the permeability and antifouling properties remain unsolved. The accurate effect of chain length is lost on the biofouling resistance behaviors. Herein, antifouling membrane surfaces of hyperbranched polyglycerol (HPG) brushes are obtained via tuning the chain lengths of HPG brush. The wettability and proteins' static adsorption are dramatically improved with the increase of HPG chain lengths. The parameter of chain volume overlap is preliminarily involved to describe the spatial distribution of HPG brushes. Unexpectedly, we demonstrate that the chain length of HPG is critical and a medium-length HPG brush displays an emerging permeability by a dense enough chain volume overlap (Dv) of the HPG architecture. The biofouling resistance behaviors are optimized using the response surface methodology. As the HPG brush grafting density increased, a higher flux recovery regardless of the chain lengths is observed. Qualitative and quantitative assays of E. coli and S. aureus attachment further reveal the low fouling characteristics of hyperbranched membrane surfaces. A deeper understanding of how the chain length of polymer brushes impacts permeability and the anti-biofouling property provides general guidance on the effectiveness of grafted polymer brushes.

Precise Pore Size Tailoring and Surface Chemistry Modification of Polycarbonate Membranes Using Atomic Layer Deposition

Physical and chemical surface modifications are commonly used in many applications such as energy generation and storage, microelectronics, water purification, gas separation, and medical/plant biology. In recent several years, sequential infiltration synthesis (SIS), a variant of atomic layer deposition (ALD), has emerged as a promising technology that uses self-limiting reactions to create hybrid organic/inorganic materials within the polymer-free volume. Herein, we employed ALD/SIS of Al2O3, SnO2, Ga2O3, TiO2, and In2O3 to precisely tune the pore size and surface characteristics of track-etched polycarbonate membranes. We used in situ Fourier transform infrared spectroscopy to elucidate the chemistry for Al2O3 SIS in polycarbonate and in situ quartz crystal microbalance measurements to probe the extent of Al2O3 infiltration during SIS in polycarbonate thin films. Next, we used scanning electron microscopy, thermogravimetric analysis, and water permeance measurements to probe the pore size reduction and conformality of SIS Al2O3 in the track-etched polycarbonate membranes. We then used water permeance measurements to compare the water flux for a series of membranes with similar pore size but different pore wall chemistry and compared these results with water contact angle measurements. Interestingly, the hydrophilic metal oxide coatings yielded higher water flux values compared to hydrophobic coatings. Finally, we examined ion-selective transport in the modified track-etched polycarbonate membranes and rationalized the results using zeta potential measurements of the ALD metal oxides. Keywords: atomic layer deposition; sequential infiltration synthesis; metal oxides; hydrophilicity/hydrophobicity; permeability; surface charge; ion conductivity/selectivity.

Ganglioside-Enriched Phospholipid Vesicles Induce Cooperative Aβ Oligomerization and Membrane Disruption.

A major hallmark of Alzheimer's disease (AD) is the accumulation of extracellular aggregates of amyloid-β (Aβ). Structural polymorphism observed among Aβ fibrils in AD brains seem to correlate with the clinical subtypes suggesting a link between fibril polymorphism and pathology. Since fibrils emerge from a templated growth of low-molecular-weight oligomers, understanding the factors affecting oligomer generation is important. Membrane lipids are key factors to influence early stages of Aβ aggregation and oligomer generation, which cause membrane disruption. We have previously demonstrated that conformationally discrete Aβ oligomers can be generated by modulating the charge, composition, and chain length of lipids and surfactants. Here, we extend our studies into liposomal models by investigating Aβ oligomerization on large unilamellar vesicles (LUVs) of total brain extracts (TBE), reconstituted lipid rafts (LRs), or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Varying the vesicle composition by specifically increasing the amount of GM1 gangliosides as a constituent, we found that only GM1-enriched liposomes induce the formation of toxic, low-molecular-weight oligomers. Furthermore, we found that the aggregation on liposome surface and membrane disruption are highly cooperative and sensitive to membrane surface characteristics. Numerical simulations confirm such a cooperativity and reveal that GM1-enriched liposomes form twice as many pores as those formed in the absence GM1. Overall, this study uncovers mechanisms of cooperativity between oligomerization and membrane disruption under controlled lipid compositional bias, and refocuses the significance of the early stages of Aβ aggregation in polymorphism, propagation, and toxicity in AD.

Characterization of polyamide thin film composite membranes incorporated silver nanoparticles

AbstractIn this study, the polyamide thin film composite membrane surface has been modified by anti‐microbial silver nanoparticles (AgNPs). The membrane surfaces were interwoven with AgNPs by ultraviolet grafting polymerization method using AgNPs with or without poly(ethylene glycol) (PEG). The membrane surface characteristics were determined by scanning electron microscopy–energy dispersive x‐ray spectrometry images, attenuated total reflection–Fourier transforms infrared spectroscopy, water contact angle values, and anti‐bacterial property. The separation performance was determined based on the flux and the ability to remove calcium ions in water. The anti‐biofouling property was appraised through the maintained flux ratios and the irreversible fouling factors of unmodified and modified membranes during 10 h‐filtration of protein bovine serum albumin (BSA) in an aqueous solution, in which, before filtration of BSA, all membranes were immersed in E. coli bacteria solution for 4 days. The results of the experiments corroborated the hydrophilicity and more anti‐microbial property of the membrane surfaces after being incorporated into AgNPs. The water contact angle decreased from around 49° for the unmodified membrane to 36° and 23° for the AgNP‐modified membranes without/with PEG, while no colonies appeared in the medium containing the AgNP‐modified membranes. The separation property of modified membranes was improved, with both membrane flux and antifouling properties, along with the substantial surge of the anti‐biofouling property. After 10 h of BSA filtration, the fluxes of the modified membranes were maintained at 68% and 78% for AgNP‐modified membranes without and with PEG, respectively. Conversely, this value was only 46% for the unmodified one.

Recent advances in nanofiltration, reverse osmosis membranes and their applications in biomedical separation field

In the face of human society's great requirements for health industry, and the much stricter safety and quality standards in the biomedical industry, the demand for advanced membrane separation technologies continues to rapidly grow in the world. Nanofiltration (NF) and reverse osmosis (RO) as the high-efficient, low energy consumption, and environmental friendly membrane separation techniques, show great promise in the application of biomedical separation field. The chemical compositions, microstructures and surface properties of NF/RO membranes determine the separation accuracy, efficiency and operation cost in their applications. Accordingly, recent studies have focused on tuning the structures and tailoring the performance of NF/RO membranes via the design and synthesis of various advanced membrane materials, and exploring universal and convenient membrane preparation strategies, with the objective of promoting the better and faster development of NF/RO membrane separation technology in the biomedical separation field. This paper reviews the recent studies on the NF/RO membranes constructed with various materials, including the polymeric materials, different dimensional inorganic/organic nanomaterials, porous polymeric materials and metal coordination polymers, etc . Moreover, the influence of membrane chemical compositions, interior microstructures, and surface characteristics on the separation performance of NF/RO membranes, are comprehensively discussed. Subsequently, the applications of NF/RO membranes in biomedical separation field are systematically reported. Finally, the perspective for future challenges of NF/RO membrane separation techniques in this field is discussed.

Influence of the Pyrolysis Temperature and TiO2-Incorporation on the Properties of SiOC/SiC Composites for Efficient Wastewater Treatment Applications.

This study focuses on the development of porous ceramer and SiOC composites which are suitable for microfiltration applications, using a mixture of polysiloxanes as the preceramic precursor. The properties of the membranes—such as their pore size, hydrophilicity, specific surface area, and mechanical resistance—were tailored in a one-step process, according to the choice of pyrolysis temperatures (600–1000 °C) and the incorporation of micro- (SiC) and nanofillers (TiO2). Lower pyrolysis temperatures (<700 °C) allowed the incorporation of TiO2 in its photocatalytically active anatase phase, enabling the study of its photocatalytic decomposition. The produced materials showed low photocatalytic activity; however, a high adsorption capacity for methylene blue was observed, which could be suitable for dye-removal applications. The membrane performance was evaluated in terms of its maximum flexural strength, water permeation, and separation of an oil-in-water emulsion. The mechanical resistance increased with an increase of the pyrolysis temperature, as the preceramic precursor underwent the ceramization process. Water fluxes varying from 2.5 to 370 L/m2·h (2 bar) were obtained according to the membrane pore sizes and surface characteristics. Oil-rejection ratios of 81–98% were obtained at an initial oil concentration of 1000 mg/L, indicating a potential application of the produced PDC membranes in the treatment of oily wastewater.

Improved hemocompatibility of polysulfone hemodialyzers with Endexo® surface modifying molecules.

Anticoagulation therapy is widely used to reduce clotting during hemodialysis (HD), but may cause adverse effects in end-stage kidney disease patients. A new hemodialyzer with a membrane modified by surface modifying molecule was developed to improve hemocompatibility that aimed to reduce the need for anticoagulation during dialysis treatments. We compared membrane surface characteristics and in vitro hemocompatibility of the new hemodialyzer to the standard polysulfone (PSF) hemodialyzer membrane. Scanning electron microscopy, contact angle measurement (68° ± 3° test vs. 41.6° ± 6° control), and X-ray photoelectron spectrometry measurement for fluorine atomic % (7.4% ± 0.4% test vs. not detectable control), showed that the membrane surface was modified with surface modifying macromolecule (SMM1) but maintained membrane structure and surface hydrophilicity. Zeta potential of the blood-contacting surface showed that the absolute surface charge was reduced at neutral pH (-3.3mV ± 1.1mV test vs. -15.6mV ± 1.0mV control). Platelet count reduction was significantly less for the SMM1-modified dialyzer (40.88% ± 21.89%) compared to the standard PSF dialyzer (62.62% ± 34.13%), along with Platelet Factor 4 (1824.10ng/ml ± 436.26 ng/ml test vs. 2479.00 ng/ml ± 852.96 ng/ml control). These studies demonstrate the successful incorporation of SMM1 into the new hemodialyzer with the expected results. Our in vitro experiments indicate that the SMM1-modified hemodialyzers could improve hemocompatibility compared to standard PSF hemodialyzers and have the potential to minimize the patient's anticoagulant requirements during HD. Additional research with SMM1 additives incorporated into the entire dialysis circuit and use in a clinical settings are required to confirm these promising findings.

Alkali-resistant polyethyleneimine/triglycidyl isocyanurate nanofiltration membrane for treating lignin lye

Lignin is a widely used biomass material and has great application potential in papermaking, textile, petrochemical industry, etc. However, the traditional separation and extraction method for the lignin system has some disadvantages in energy consumption and separation effect, which greatly limited the application of lignin. The rapid development of nanofiltration (NF) membranes provides new ideas for solving this problem. The PEI/TGIC membrane with great alkali resistance (pH 7–14) by cross-linking polyethyleneimine (PEI) and triglycidyl isocyanurate (TGIC) was developed in this work. The influencing factors of membrane surface characteristics were discussed and membrane preparation parameters were optimized. The optimized PEI/TGIC membrane (prepared with 0.02% TGIC and 0.8% PEI) had the characteristics of high permeability and selectivity under low pressure (2 bar). The PEI/TGIC membrane was stable to the removal of PEG 1500 in an alkaline environment (pH 7–14). For lignin lye, the PEI/TGIC membrane could intercept the lignin (rejection>95%) while allowing the sodium hydroxide to almost completely penetrate. Under the operating pressure of 2 bar, the lye permeation flux could be maintained at 22 L m−2 h−1. This work provided new ideas for the application of nanofiltration membranes and the treatment of lignin lye.

Influence of Ceramic Membrane Surface Characteristics on the Flux Behavior of a Complex Fermentation Broth.

The valorization of agro-industrial residues using yeasts as biocatalysts requires efficient methods for biomass separation. Filtration with ceramic membranes is suitable for this task, however, the challenge of flux decline and the unavoidable cleaning must be taken into account. We investigated the filtration of fermentation broth and its components using tubular microfiltration and ultrafiltration membranes, and hollow-fiber ultrafiltration membranes, with cut-offs of 30 and 200 nm. The steady-state flux was limited by fouling under comparable wall shear stress conditions but increased when the wall shear stress was higher. Single-component filtration with two 30 nm tubular ultrafiltration membranes, whose average surface roughness ranged from 1.0 to 3.9 µm, showed that smoother surfaces experience less biomass fouling under more intense hydrodynamic conditions. Furthermore, we showed experimentally and by scanning electron microscopy in filtration with 30 nm tubular membranes that the thickness of the first separation layer is responsible for the degree of irreversible resistance caused by the deposition of organic material in the membrane pores. The thickness of this layer should therefore be minimized without compromising mechanical stability.

Modified polyvinyl chloride membrane grafted with an ultra-thin polystyrene film: structure and electrochemical properties

The work explores the synthesis and the properties of a novel composite membrane system based on modified polystyrene (PS) grafted onto a polyvinyl chloride (PVC) membrane. PVC membranes were prepared by solution-casting followed by exposure to an atmospheric pressure dielectric barrier discharge (DBD) with O2 to obtain an activated surface for grafting PS to it. Moreover, the thus prepared membranes were chemically modified furthermore by amination with polyethyleneimine or sulfonation with 4 M sulfuric acid. The membrane surface characteristics such as wettability, structure and morphology were investigated using water contact angle measurements, attenuated total reflection Fourier transform infrared spectroscopy and scanning electron microscopy experiments. The thermogravimetric stability and electrolytic responses of the membranes were studied utilizing TGA, ion exchange capacity (IEC), and solvent uptake. A significant result of plasma and chemical modification was to produce a membrane material with low permeability. Thus, the methanol permeability of the sulfonated membranes measured for 12 h was measured to 2.34·10−8 cm2 s−1 compared to 177.00·10−8 cm2 s−1 of Nafion 117® which is considered as a benchmark. This result indicates that the prepared sulfonated samples are an innovative and effective material for decreasing the methanol crossover in fuel cells to a great extent. This makes the PVC-g-St membranes are promising and attractive as new materials for polyelectrolyte membrane for fuel cells.