Membrane Surface Roughness Research Articles

Self-assembled ILs-PVA micelle nanostructure impart the pervaporation membrane with high ethanol dehydration performance

Achieving strong interaction with the targeted composition and constructing abundant transport channels is crucial to obtain the pervaporation (PV) membrane with high selectivity and flux. Here, three ionic liquids (ILs) were screened out based on their relative selectivity and capacity targeting for bioethanol dehydration by COSMO-RS. The interaction energies analysis between ILs, EtOH, and H2O suggests that the ILs can form strong hydrogen bonds with water and disrupt the hydrogen bond in the EtOH–H2O azeotropic mixture, which is beneficial for improving the selectivity. Furthermore, driven by the multiple hydrogen bonds, electrostatic interactions, and van der Waals forces, ILs could self-assemble with polyvinyl alcohol (PVA) to fabricate the PV membrane with well-ordered micelle nanostructure, as its structure was revealed by MD simulations. The formation of the ILs-PVA micelle dramatically influenced membrane surface morphology, roughness, and water contact angle, providing an extra transport channel for the membrane. The optimal membrane (at the cmc point) exhibited a superior ethanol dehydration separation factor of 1627, along with a flux of 684 g/m2h at 50 °C. It can be expected that this novel self-assembled ILs-PVA micelle nanostructure strategy will find promising applications in other azeotropic mixture separation processes, like ethanol-ethyl acetate, water-butanol, etc.

Polycaprolactone-zinc oxide biocomposite membranes for wastewater treatment by ultrafiltration process: Synthesis, characterization and removal of inorganic pollutants

The severe droughts impacting North Africa have intensified the pressure on potable water supplies and agricultural irrigation, highlighting the urgent need for sustainable water management solutions. This study explores the potential of poly(ε-caprolactone)/zinc oxide (PCL/ZnO) biocomposites as ultrafiltration membranes for treating urban wastewater, with the goal of enabling water reuse in agriculture. PCL/ZnO membranes, fabricated using the solvent-casting method, were thoroughly characterized using FTIR, XRD, EDAX, SEM, AFM, DSC, TGA, and water contact angle (WCA) measurements. Key findings revealed that increasing ZnO content (1–4 wt%) significantly enhanced membrane thickness, crystallinity, mechanical robustness, and surface roughness, while lowering WCA values to improve hydrophilicity. These enhanced properties are critical for ultrafiltration, as they contribute to higher contaminant rejection and improved water permeability. Performance tests demonstrated ion retention rates of 32–61 % post-filtration, including for toxic metals, effectively reducing pollutant levels. Notably, the treated water met the Food and Agriculture Organization (FAO) standards for irrigation quality, indicating its suitability for agricultural applications. This work highlights the efficacy of PCL/ZnO membranes in facilitating sustainable wastewater recycling under drought conditions, presenting a promising, adaptable solution for water reclamation in water-scarce regions. The results underscore the potential of these biocomposite membranes to advance sustainable water treatment practices, supporting both environmental resilience and agricultural productivity.

One-step development of photothermal omniphobic membrane for vacuum membrane distillation towards sustainable water desalination using solar energy

Nowadays, development of photothermal omniphobic membranes (POMs) for water desalination using solar energy has gained considerable attention to face water and energy challenges in a sustainable way. Scientists have been developing POM via different techniques based on photothermal component loading and surface energy reduction, all of which suffer from multi-step processes. Obviously, researchers and especially industrial developers aspire to one-step techniques that make the production process highly accelerated and economical. In this study, a one-step technique to develop POMs is demonstrate, using which the omniphobic and photothermal properties are simultaneously imparted to the membrane through being integrated with the membrane fabrication process. The technique works based on elaborate design of membrane surface chemistry and roughness via electrospinning of poly(vinylidene fluoride) (PVDF)/poly(1H,1H,2H,2H-perfluorooctyl acrylate) (PPFOA) blend solution containing carbon black nanoparticles (CB NPs). Optimum concentrations for PPFOA and CB NPs with respect to the PVDF weight were obtained as 60 and 15 wt%, respectively. The developed membrane exhibited permeate flux and salt rejection as high as 2.94 kg/m2·h and > 98 %, respectively, under one sun radiation. Evaporation rate and efficiency of the developed membrane were calculated as 1.49 kg/m2.h and 83.5 %, respectively. The membrane exhibited stable long-term performance for 600 min in contact with the sodium dodecyl sulfate (0.8 mM)-containing NaCl aqueous solution (3.5 wt%). Besides single-step implementation, the introduced technique benefits from endowing the entire membrane structure with omniphobic and photothermal properties not only the membrane surface. This can drastically improve the membrane performance and life time.

MONOCRYSTALLINE DIAMOND MEMBRANES WITH A THICKNESS OF 10 MICRONS, MANUFACTURED BY PLASMA ETCHING

New applications of high-quality synthetic diamond in sensors and integrated photonic circuits, which are being rapidly developed nowdays, often demand freestanding diamond membranes with a thickness of about 10 microns as a substrate. However, the process of thin single-crystal diamond membranes fabrication, as well as their subsequent processing are challenging due to the high hardness, chemical resistance and brittleness of the material. Our work demonstrates a method for creating freestanding diamond membranes mounted on a thick diamond substrate using reactive ion etching of single-crystalline diamond wafers in plasma with mechanical protective masks. The optimal thickness of a diamond wafer for membranes etching is determined in the range from 100 to 120 µm with mandatory plane-parallel polishing of the sides. We experimentally studied the interaction of RF discharge SF6 based plasma with diamond surface during deep etching with mechanical protective masks of various shapes. It was found that the use of thick masks leads to an uneven rate of diamond etching over the entire area of the formed membrane. We have assessed ion sputtering resistance of various mask materials in SF6 based plasma, and found the most promising mask materials for deep diamond etching (steel, copper, diamond). We have fabricated diamond membranes with a thickness of 11,5 µm (and more), mounted on a durable 60 µm (and more) thick frames, and studied their characteristics. After etching membrane surface roughness was less than 25 nm, and the unevenness of their thickness did not exceed 20%. Also, we compare different methods for controlling the depth of diamond etching and the thickness of the resulting membranes, including mechanical measurements, IR spectral reflectometry, optical profilometry and electron microscopy. For citation: Golovanov A.V., Yun M.I., Bondarenko M.G., Prosin A.A., Tarelkin S.A. Monocrystalline diamond membranes with a thickness of 10 microns, manufactured by plasma etching. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 10. P. 55-64. DOI: 10.6060/ivkkt.20246710.1y.

Surface treatment optimization of mixed cellulose ester membrane by cold plasma treatment to improve apple juice clarification

This study aimed to determine the optimal conditions for the surface modification of mixed cellulose ester (MCE) microfiltration membrane by cold plasma (CP) for apple juice clarification. Response surface method using central cubic design (CCD) was employed for the optimization of the membrane surface modification process. Plasma gas type (oxygen, carbon dioxide, and air), power (10, 15, and 20 W), and exposure time (120, 180, and 240 s) were used as the factors for cold plasma surface modification. The results revealed the surface modification of the MCE membrane using air as plasma gas with plasma power and exposure time equal to 10 W and 180 s resulted in the maximum permeate flux in apple juice clarification. The results of scanning electron microscope, and atomic force microscope confirm the effect of CP treatment on the membrane surface roughness. Fourier transform infrared spectroscopy showed the incorporation of the hydroxyl group into the membrane surface due to CP treatment which affected the surface contact angle and hydrophilicity. The CP treatment of the membrane significantly affects the membrane resistances. Also, the surface modification of the MCE membrane using the CP treatment process in optimal conditions is an effective method for clarifying apple juice.

Superhydrophobic poly(lactic acid) membrane prepared with the induction of modified carbon dots for efficient separation of water-in-oil emulsions

Superhydrophobic separation membranes are considered to be one of the most promising technologies for oil-water separation. However, the plastic waste generated from discarded membranes poses a challenge to the preparation of degraded superhydrophobic separation membranes for achieving eco-friendly separation. In this study, superhydrophobic poly(lactic acid) (PLA) membranes were fabricated using a non-solvent induced phase separation method assisted by l-cysteine modified carbon dots (Cys-CDs). The synergistic effect of Cys-CDs-induced crystallization behavior of PLA and the phase separation process results in the evolution of the surface of the PLA-based membrane from a pistil-like structure to a multi-level micro-nano structure composed of dense lamellar nanofibers and microspheres with an increase in Cys-CDs content. At a Cys-CDs content of 5 wt%, the surface roughness of PLA-based separation membrane reached its maximum, and the water contact angle was as high as 159°. Remarkably, the superhydrophobic Cys-CDs/PLA membrane exhibited promising performance in the separation of water-in-oil emulsions, with a rejection rate of 99.98% and a flux of 315.74 L·m−2·h−1·bar−1. Additionally, the superhydrophobic Cys-CDs/PLA separation membrane also demonstrates impressive properties such as acid-alkali resistance and rapid recycling into high-value chemicals. Consequently, this rapidly recoverable superhydrophobic porous Cys-CDs/PLA membrane shows great potential for practical applications in actual oil-water separation.

Exploration of self-crosslinking induced surface modification using APTES on the PA RO membrane for excellent anti-fouling performance

The physicochemical properties of the polyamide reverse osmosis (PA RO) membrane surface play a crucial role in membrane fouling. In this work, a silicon-based material, γ-Aminopropyl triethoxysilane (APTES), was incorporated onto the PA membrane surface by self-crosslinking induced surface modification to improve its antifouling properties. FTIR and XPS analyses reveal that APTES primarily bonded to the pristine PA membrane via amidation between –NH2 groups in APTES and residual –COCl groups on the membrane surface, and then combined with each other to form Si–O–Si groups (even Si–O–Si networks). The incorporation of APTES reduces the membrane surface energy and roughness, and the surface potential of the membranes can be adjusted by varying the APTES addition. Meanwhile, the pure water permeance of the APTES-PA membrane reached ~3.77 LMH/bar while maintaining a NaCl rejection of ~98.65%. Additionally, although the negative charge of the APTES-PA (M0.15) membrane increases, the antifouling against electropositive small molecular foulants is enhanced, mainly due to the low-surface-energy of the APTES-modified layer. Furthermore, the stability of the APTES-modified layer in the presence of electronegative small molecular foulants with strong decontamination capabilities can be reinforced by a simple high-temperature heat treatment. Broadly speaking, surface modification of the PA RO membrane by APTES combining grafting with self-crosslinking induced method is beneficial for its anti-fouling and reuse.

Fabrication and performance optimization of an advanced pervaporation desalination membrane: A study utilizing PVDF and hydrophilic active layer as composite

Pervaporation emerges as a promising technique for brine treatment. In this investigation, we employed a PVDF substrate layer and applied various coating solutions using a simple spray technique to produce a composite pervaporation membrane. The composite membrane's chemical structure, morphology, hydrophilicity, swelling property, surface roughness, and crosslinking conditions were thoroughly investigated. Notably, the PVDF/PEI/P(SS-MA) composite membrane exhibited outstanding desalination performance, demonstrating high salt rejection and flux of 308.7 ± 13.8 kg m−2 h−1 when subjected to a 3.5 wt% sodium chloride solution. Even at an elevated brine concentration of 20 wt%, the membrane maintained a commendable flux of 88.76 ± 5.4 kg m−2 h−1 at 72 °C. These findings underscore the efficacy of the developed composite membrane for brine desalination applications.

A negatively charged polyethersulfone nanofiltration membrane enriched with Ag-functionalized titanium silicon carbide for the removal of organic pollutants from water

Developing high-performance nanofiltration membranes for treating wastewater contaminated with organic pollutants requires special attention. The toxic nature and side effects of organic pollutants, such as dyes and antibiotics, make them hazardous. Therefore, wastewater containing organic pollutants must be treated properly before entering water environments. Herein, we synthesized the Ti3SiC2 MAX phase via the reactive sintering technique. To make the Ti3SiC2 more hydrophilic and compatible with the polyethersulfone (PES) membrane, its surface was modified in one step with Ag NPs/polyvinyl alcohol (Ag-MAX). Different quantities (0–1 wt%) of Ag-MAX filler were embedded into the PES membrane via the phase inversion process. The presence of 0.75 wt% Ag-MAX filler enhanced hydrophilicity, porosity, surface roughness, pore size, and negative charge of PES membrane, which are beneficial for permeance and antifouling features of Ag-MAX mixed matrix membranes (MMMs). The optimized membrane containing 0.75 wt% of Ag-MAX demonstrated the uppermost pure water flux of 72.5 L/m2 h with a flux recovery ratio of 82.8 %. The optimized membrane showed rejection efficiency of 99.4, 99.6, and 99.7 % for Direct Black 38, Acid Blue 113, and Disperse Red 153 dye solutions, along with a satisfactory rejection of 70.7, 65.9, and 58.5 % for Basic Violet 1, Alizarin Red S, and Ceftriaxone solutions, respectively. Furthermore, the effects of various pH values, various salt types, and cyclic filtration experiments on the separation performance of 0.75 wt% Ag-MAX MMM were investigated. The rejection efficiency of 0.75 wt% Ag-MAX MMM toward Acid Blue 113 is almost constant and higher than 98.5 % in different conditions, demonstrating that the Ag-MAX MMM could be a suitable candidate for the treatment of wastewater contaminated with organic pollutants.

Preparation of antifouling reverse osmosis membrane with polyacrylic acid brushes based on polydopamine coating assisted atom transfer radical polymerization

An antifouling polyamide (PA) reverse osmosis (RO) membrane was fabricated in this work by incorporating polyacrylic acid (PAA) brushes onto the membrane surface via polydopamine (PDA)-assisted atom transfer radical polymerization (ATRP). Specifically, a PDA intermediate layer containing the initiator 2-bromoisobutyryl bromide (BIBB) for polymerization was coated on original membrane surface. Then, acrylic acid (AA) was controllably incorporated on the membrane surface in the form of PAA brushes by regulating ATRP reaction time. The PDA-assisted polymerization was mild to the separation layer, and BIBB could be immobilized on the membrane surface with even distribution and controllable density. It was demonstrated that the water contact angle and surface roughness of the RO membranes with PAA brushes was reduced, while the negative charge and hydrophilicity were increased. Simultaneously, the water flux of the membrane was enhanced by 27.8% and the NaCl rejection was maintained compared with that of virgin membrane. Moreover, the modified membrane presented a higher flux recovery ratio and a lower flux decline ratio when lysozyme, bovine serum albumin, humic acid, and sodium alginate were used as model foulants. Besides, the membrane exhibited a satisfactory long-term performance stability. Our work provides a gentle and controllable strategy for the fabrication of antifouling RO membranes with enhanced water permeability and maintained salt rejection, which is crucial for increasing the efficiency of RO processes.

An Innovative Surface Modification Technique for Antifouling Polyamide Nanofiltration Membranes.

In this study, we developed a novel surface coating technique to modify the surface chemistry of thin film composite (TFC) nanofiltration (NF) membranes, aiming to mitigate organic fouling while maintaining the membrane's permselectivity. We formed a spot-like polyester (PE) coating on top of a polyamide (PA) TFC membrane using mist-based interfacial polymerization. This process involved exposing the membrane surface to tiny droplets carrying different concentrations of sulfonated kraft lignin (SKL, 3, 5, and 7 wt %) and trimesoyl chloride (TMC, 0.2 wt %). The main advantages of this surface coating technique are minimal solvent consumption (less than 0.05 mL/cm2) and precise control over interfacial polymerization. Zeta potential measurements of the coated membranes exhibited enhancements in negative charge compared to the control membrane. This enhancement is attributed to the unreacted carboxyl functional groups of the SKL and TMC monomers, as well as the presence of sulfonate groups (SO3) in the structure of SKL. AFM results showed a notable decrease in membrane surface roughness after polyester coating due to the slower diffusion of SKL to the interface and a milder reaction with TMC. In terms of fouling resistance, the membrane coated with a polyester composed of 7 wt % SKL showed a 90% flux recovery ratio (FRR) during Bovine Serum Albumin (BSA) filtration, showing a 15% improvement compared to the control membrane (PA). PE-coated membranes provided stable separation performance over 40 h of filtration. The sodium chloride rejection and water flux displayed minimal variations, indicating the robustness of the coating layer. The final section of the presented study focuses on assessing the feasibility of scaling up and the cost-effectiveness of the proposed technique. The demonstrated ease of scalability and a notable reduction in chemical consumption establish this method as a viable, environmentally friendly, and sustainable solution for surface modification.

Self-cleaning of metal-organic framework membranes achieved by photocatalytic ZIFs for dye and antibiotic separation

The progress of membrane-based applications is hindered by widespread membrane fouling, which leads to a significant decrease in separation effectiveness and lifespan, even though membrane separations have shown great potential in the treatment of dye wastewater. The metal-organic framework MOFs (ZIF-8) display strong thermal and chemical stability and an exceptional capacity to degrade organic molecules under visible light, making them extremely promising for the development of self-cleaning membranes. In this investigation, a ZIF-8/L-DOPA/PVDF mixed matrix membrane with excellent self-cleaning properties was constructed using the in-situ growth technique. The characterization results confirmed the formation of a continuous ZIF-8 coating layer, considerably increasing the surface roughness of the composite membrane from 22.9 nm to 76.3 nm compared to L-DOPA/PVDF substrates. The ZIF-8 layer deposited on the L-DOPA/PVDF membrane surface reduced the contact angle from 75.71° to 40.94°. The highest-performing ZIF-8/L-DOPA/PVDF membranes show a higher water permeability of 159.63 (L·m−2 h−1 bar−1) and superior dye rejection rates (Congo red: 97.3 %, Methylene Blue: 98.32 %, Methyl Blue: 98.62 %), along with enhanced removal of antibiotics (e.g., Tetracycline: 95.3 % and Ciprofloxacin: 93.34 %), and long-term nanofiltration stability. Furthermore, the treated membrane recovers almost all of its initial separation efficacy after exposure to visible light due to the successful removal of attached dyes from the membrane surface through photocatalysis. This work presents the potential to fabricate membranes with advantageous photocatalytic properties and effectively treat dye wastewater using self-cleaning membranes.

Cross-flow photocatalytic membrane reactor (PMR) based on TiO2–AgBr–Ag–NH2-MIL-88B (Fe) /poly (ethersulfone) for enhanced removal of cefixime, anti-fouling performance and permeability

The organic-metallic framework NH2-MIL-88B (Fe) was initially synthesized using a hydrothermal process., then the TiO2–AgBr–Ag–NH2-MIL-88B (Fe) photocatalytic nanoparticles was successfully ready and used as a filler for mixed matrix membrane (MMM) poly Ether sulfone (PES) was added. A photocatalytic membrane reactor (PMR) for the degradation of cefixime aqueous solution (CFX) was fabricated using a PES-TiO2-AgBr-Ag–NH2–MIL-88B (Fe) flat sheet membrane module. FTIR, XRD, FESEM, and DRS analyses were performed to look into the produced nanoparticles' structural characteristics. Hydrophilicity and membrane surface roughness were investigated using the surface contact angle and AFM pictures test. Additionally, Cross-FESEM analysis was used to examine modifications in membrane morphology. By increasing the TiO2–AgBr–Ag–NH2-MIL-88B (Fe) nanoparticles in the polymer matrix, significant improvements were made to the membrane's hydrophilicity, porosity, pure water flux, and CFX degradation. Furthermore, the nanocomposite membranes' antifouling characteristic was assessed while the CFX solution was being filtered. The obtained results show that the flux and removal of CFX solution is improved by adding TiO2–AgBr–Ag–NH2-MIL-88B (Fe) nanoparticles to PES polymer solution up to 1 % by weight. In addition, the obtained results showed that the addition of TiO2–AgBr–Ag–NH2-MIL-88B (Fe) photocatalytic nanoparticles in the PES membrane significantly improves the antifouling properties.

Electrospun bio-polymeric nanofibrous membrane for membrane distillation desalination application

Polylactic acid (PLA) has been explored as a sustainable material for membrane distillation (MD) membranes using electrospinning for the first time. Adjusting the electrospinning parameters of PLA nanofiber, such as concentration, voltage, collector distance, humidity, and flow rate, resulted in uniformly distributed and smaller nanofibrous structures. Heat treatments were also performed to enhance the tackiness and fusibility of the fibers within the nanofibrous structure, optimizing the pore size, hydrophobicity, and surface roughness of the PLA membranes. The hierarchical structure of the PLA membranes improved the liquid entry pressure (LEP) and mechanical strength by 320 % and 230 %, respectively. The membrane characteristics were assessed in terms of porosity, pore size, surface roughness, and contact angle, which determined the impact of the wettability of the membrane under different conditions. The results showed that under certain constraints, PLA membranes could be effectively used in the air gap membrane distillation (AGMD) process, achieving a permeated flux of ~2 kg/m2h and a salt rejection of 99 %. However, PLA-based nanofibrous membranes are unsuitable for MD applications at feed temperatures above 60 °C and a flow rate of 60 LHP. This study provides a strong basis for developing and manufacturing eco-friendly bio-based nanofibers materials for desalinating saltwater.

One step co-sintering synthesis of asymmetric metal membrane with smooth surface for microfiltration

In this paper, a novel fabrication method for manufacturing tubular micro-filtration membrane with mirror-like surface by one step co-sintering without additive doping has been developed. The result shows that the metallic membrane was bonded to the support tightly after sintering at 1250 °C for 2 h. The fine powder content has a significant impact on the integrity of the membrane layer, which is due to the synergistic shrinkage during the co-sintering process. The surface roughness and average pore size of the as-fabricated stainless-steel membranes by the new method are 178 nm and 2.1 μm, respectively.

Effect of Electrospinning Parameters on the Morphological and Thermal Properties of ABS/ENR Electrospun Fibres

The electrospun of the Acrylonitrile-butadiene-styrene (ABS) blend with epoxidized natural rubber (ENR) is fabricated using the electrospinning technique. Research shows that ABS/ENR electrospun fibres have not been studied. The effects of electrospinning parameters were investigated to determine a significant effect on the microstructure, surface roughness, fibre diameter, and fibre distribution of the electrospun membranes. Sample preparation is made straightforwardly by dissolving ABS and ENR in acetone solvent using a magnetic stirrer. In this research, there are two solution parameters being studied: the ABS/ENR solution concentration (15 to 25 wt.%) and the ratio of ENR (100:0, 70:30, 50:50). Meanwhile, process parameters that are being studied are applied voltage (15 kV to 30 kV) and distance from syringe tip to collector (5cm to 15cm). FTIR results showed that hydrogen bond interaction occurs between ABS and ENR. According to the SEM images, micrometre and sub-micrometre fibres with a smooth surface and bead formation were produced at a concentration of 25%, a ratio of 70:30, a voltage of 30kV, and a distance of 15cm. The diameter of electrospun fibres increases with increasing solution concentration, ranging from 400 nm to 4.5 µm. The diameter of the electrospun fibres decreased with the addition of ENR, increasing voltage, and tip-to-collector distance. TGA results showed that ABS/ENR blends gave higher degradation temperature (393.7°C) than pure ABS (368.8°C), which enhanced thermal stability.

Preparation and separation performance of biomimetic polycaprolactone/graphene oxide composite membrane

The treatment of oil and water pollutants generated in industrial production and daily life is an urgent issue that needs to be addressed globally. Inspired by superhydrophobic self-cleaning lotus leaves, durable and sturdy superhydrophobic water-filled barriers, and lightweight bird bones with hollow structures, researchers can obtain superhydrophobic surfaces by creating rough surfaces of layered micro- and nanostructures. In this study, hydrophobic polycaprolactone (PCL) membranes with layered structures were prepared by electrospinning. The surface roughness of the PCL membrane was improved by compounding graphene oxide (GO) functional components on the PCL membrane surface, thereby enhancing its hydrophobicity. The infrared spectrum of the PCL/GO membrane shows that PCL and GO are physically mixed, and no chemical changes occur during the electrospinning process. Scanning electron microscopy (SEM) images of the composite fibre membranes reveal the interconnections between fibres. Fourier transform infrared spectroscopy (FTIR) provides information on the chemical components of the membranes. Thermogravimetric analysis (TGA) was employed to assess the thermal stability of the membranes. The oil-water separation test demonstrated that the PCL/GO membrane exhibited a separation efficiency of 99.94% for hexane-water mixtures. In the oil adsorption test, the maximum adsorption capacity of the membrane for n-hexane was 35.8 g/g. In the contact angle measurement experiment, the water contact angle of the nanofiber membrane increased from 120.12° to 140.15° with increasing GO content, indicating that the composite membrane exhibited enhanced hydrophobicity.

Mechanism of hypoxia-induced damage to the mechanical property in human erythrocytes-band 3 phosphorylation and sulfhydryl oxidation of membrane proteins.

Introduction: The integrity of the erythrocyte membrane cytoskeletal network controls the morphology, specific surface area, material exchange, and state of erythrocytes in the blood circulation. The antioxidant properties of resveratrol have been reported, but studies on the effect of resveratrol on the hypoxia-induced mechanical properties of erythrocytes are rare. Methods: In this study, the effects of different concentrations of resveratrol on the protection of red blood cell mor-phology and changes in intracellular redox levels were examined to select an appropriate concentration for further study. The Young's modulus and surface roughness of the red blood cells and blood viscosity were measured via atomic force microsco-py and a blood rheometer, respectively. Flow cytometry, free hemoglobin levels, and membrane lipid peroxidation levels were used to characterize cell membrane damage in the presence and absence of resveratrol after hypoxia. The effects of oxida-tive stress on the erythrocyte membrane proteins band 3 and spectrin were further investigated by immunofluorescent label-ing and Western blotting. Results and discussion: Resveratrol changed the surface roughness and Young's modulus of the erythrocyte mem-brane, reduced the rate of eryptosis in erythrocytes after hypoxia, and stabilized the intracellular redox level. Further data showed that resveratrol protected the erythrocyte membrane proteins band 3 and spectrin. Moreover, resistance to band 3 pro-tein tyrosine phosphorylation and sulfhydryl oxidation can protect the stability of the erythrocyte membrane skeleton net-work, thereby protecting erythrocyte deformability under hypoxia. The results of the present study may provide new insights into the roles of resveratrol in the prevention of hypoxia and as an antioxidant.

Ta-Fe in-situ coating PES membrane and its application in oily wastewater treatment: Insight into modification and anti-fouling mechanisms

Membrane fouling is a serious problem that limits the widespread application of membrane technology. Herein, we propose an effective modification method by in-situ modifying polyethersulfone (PES) ultrafiltration membrane with tannic acid (TA) and Fe3+ chelates to improve its pollution resistance. The TA-Fe3+ complexes could deposit on the PES membrane surface and form a hydration layer by Van Der Waals force, hydrogen bonding force, and hydrophobic association. The modified membrane (PES\\TA\\Fe3+) had enhanced fouling resistance and membrane flux due to its dual advantages of abundant OH groups and favorable spatial structure. After modification, the roughness of membrane surface increased from 219 nm to 257 nm, and its water contact angle decreased from 58.9° to 26.5°, endowing the PES\\TA\\Fe3+ membrane with a strong resistance to oil droplets through electrostatic repulsion, steric hindrance effect, and hydrogen bonding force. Polyaluminum chloride-polydimethyldiallylammonium chloride (PAC-PDMDAAC) could alleviate 85 % membrane fouling resistance. PAC-PDMDAAC mainly mitigated irreversible membrane fouling by removing oil droplets and forming large and loose flocs. While the use of PES\\TA\\Fe3+ membrane mainly reduced the adsorption resistance and the resistance of membrane itself. The anti-fouling performance of PES\\TA\\Fe3+ membrane changed with pH owing to the changes in the properties of TA-Fe3+ complexes. The hydrophilic layer would be decomposed under alkaline conditions due to the deprotonation of TA and excessive hydrolysis of Fe3+. This study provides an efficient anti-fouling strategy and reveals the modification and anti-fouling mechanisms of the hydrophilic membrane, providing theoretical guidance for the further development of membrane technology.

Mesoporous silica-grafted deep eutectic solvent-based mixed matrix membranes for wastewater treatment: Synthesis and emerging pollutant removal performance

Abstract Nano-enhanced membrane technology and deep eutectic solvents (DESs) have demonstrated effectiveness in addressing emerging environmental pollutants. This research centers on purifying water by removing heavy metals employing membranes enhanced with mesoporous silica and DES. Various DESs, including hexanoic acid, octanoic acid, and decanoic acid, were synthesized using tetrabutylammonium bromide (TBABr) as a base. The study combined a polysulfone-based membrane with mesoporous silica, aiming for efficient indigenous crafting to remove heavy metals. Mesoporous silica was blended with the synthesized DES solution, creating diverse membranes for heavy metal separation. The study characterized these membranes using various techniques such as scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and contact angle measurements. Surface mapping confirmed the integration of silicon-based DES, reducing the membrane surface roughness from 4 to 1.4 nm. By adjusting the carboxylic acid chain length with TBABr and adding mesoporous silica, leaching ratios were reduced from 4.2 to 2.3%. Silica-grafted DES-based membranes exhibited a progressive increase in flux from 2.6 to 26.67 L/m2 h. The synthesized silicon-based membranes demonstrated outstanding performance, achieving rejection rates exceeding 80% for chromium and arsenic, maintaining an impressive 90% flux recovery ratio even at high flux rates. This study will envision the potential of nano-enhanced membrane technology utilizing DES for sustainable water purification and wastewater treatment applications to achieve the sustainable development goal (SDG) of clean water and sanitation (SDG-6).