Comparison between hydrophilic and hydrophobic metal nanoparticles on the phase separation phenomena during formation of asymmetric polyethersulphone membranes

Development of polymer electrolyte membrane based on poly(Vinyl Chloride)/graphene oxide modified with zirconium phosphate for fuel cell applications

The function of a membrane in the fuel cell is critical to its success. The major component of a direct methanol fuel cell (DMFC) is the proton exchange membrane (PEM) which must have proton conductivity, thermal stability, mechanical qualities, and low methanol permeability. In this study case, the film-forming and structural properties of Polyvinyl chloride (PVC) impelled us to employ them for developing polyelectrolyte membranes (PEMs). To functionalize the resultant PEMs, Graphene oxide (GO) and zirconium phosphate (ZrP) were incorporated into polyvinyl chloride in different proportions. The structural and physical properties of PVC/GO-ZrP membranes were investigated by using a variety of techniques instance, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Thermogravimetric analyzer (TGA), universal testing machine, and water contact angle meter. Furthermore, water uptake, Methanol uptake, and ion exchange capacity (IEC) were measured. The results demonstrated that the membranes developed have enough characteristics to be valid in DMFCs.

Tailoring Morphology and Properties of Tight Utrafiltration Membranes by Two-Dimensional Molybdenum Disulfide for Performance Improvement

To enhance the permeation and separation performance of the polyethersulfone (PES) tight ultrafiltration (TUF) membrane, two-dimensional molybdenum disulfide (MoS2) was applied as a modifier in low concentrations. The influence of different concentrations of MoS2 (0, 0.25, 0.50, 1.00, and 1.50 wt%) on TUF membranes was investigated in terms of morphology, mechanical strength properties, permeation, and separation. The results indicate that the blending of MoS2 tailored the microstructure of the membrane and enhanced the mechanical strength property. Moreover, by embedding an appropriate amount of MoS2 into the membrane, the PES/MoS2 membranes showed improvement in permeation and without the sacrifice of the rejection of bovine serum protein (BSA) and humic acid (HA). Compared with the pristine membrane, the modified membrane embedded with 0.5 wt% MoS2 showed a 36.08% increase in the pure water flux, and >99.6% rejections of BSA and HA. This study reveals that two-dimensional MoS2 can be used as an effective additive to improve the performance and properties of TUF membranes for water treatment.

Uptake of Metal (Zn, Y, Ti) Oxide Nanoparticles by Poaceae and Cucurbitaceae Plants Based On Metal Properties and Surface Conditions

Metal nanoparticles (NPs) may serve as biomarkers, as the surfaces can be chemically modified to enable an analysis of several biosystems, including plant pathogenesis. We supplied metal oxide NPs including those of ZnO, TiO₂, Y₂O₃, and Y₂O₃ doped with europium to plants of eight species of the Poaceae and Cucurbitaceae families. The plants were grown using hydroponics, where NPs were incorporated into the cultivation media. Energy-dispersive X-ray spectroscopy was used to detect the uptake of NPs by the plant in regions of the root, stem, and leaf. Results show that ZnO NPs were taken up more readily by the plants compared to other NPs. Unmodified NPs were only delivered up till the stems and not the leaves; however, when the surfaces were modified using photoinduced hydrophilization supplemented with poly(ethylene glycol), NPs were delivered to the leaves of plants. It is suggested that plants readily take up metals such as zinc that function as nutrients. Additionally, hydrophilization of NP surfaces using UV irradiation enhances uptake, where modified ZnO and TiO₂ NPs may be delivered to the leaves. These findings may be used to design biomarker systems for detecting tissue damage and infections in various crops.

A review on surface modification methods of poly(arylsulfone) membranes for biomedical applications

Considerable methods have so far been used for the surface modification of biomedical membranes. Several reviews and articles have been published on the improvements achieved in the field of poly(arylsulfone) membranes subjected to various surface modification methods and used in biomedical applications. This review concentrates on the surface modification, biological applications and future perspective of the poly(arylsulfone) biomedical membranes. Different surface modification procedures employed for the poly(arylsulfone) membranes have been classified, studied and compared. Diverse surface modification techniques include surface coating, chemical modification and immobilization/cross-linking, grafting, surface zwitterionicalization, mussel-inspired coating and layer-by-layer assembly. Furthermore, we review the recent research studies performed on the surface modification of the poly(arylsulfone) biomedical membranes. Meanwhile, the properties of biomedical membranes are also discussed in each section. At last, the future perspective and challenges of the strategies utilized for the surface modification of poly(arylsulfone) biomedical membranes are presented.

Functionalizing a Polyelectrolyte Complex with Chitosan Derivatives to Tailor Membrane Surface Properties

Polyelectrolyte complex (PEC) materials show promise in the development of tunable membranes for aqueous and organic solvent separations, as well as in the creation of surface layers for fouling control. In this study, we developed a polyelectrolyte complex (PEC) functionalized by negatively charged carboxymethyl chitosan (CMC-) and positively charged quaternized chitosan (QC+) to tailor its surface properties and antibacterial efficacy. CMC- and QC+ were prepared and characterized using FT-IR and ¹H NMR, which confirmed the presence of the carboxymethyl group and trimethylammonium group in CMC- and QC+ with 65.6% and 83.9% substitution, respectively. The CMC- functionalized PEC (CMC-/PEC) and QC+ functionalized PEC materials (QC+/PEC) were evaluated for their stability in water, resistance to organic and inorganic adsorption, and antibacterial action against a model microorganism, Pseudomonas putida. The results showed no release of chitosan derivatives after adsorption, and CMC-/PEC and QC+/PEC exhibited charge-based, selective repulsion of model organic and inorganic substances. Moreover, the functionalized PEC surfaces displayed lower bacterial attachment due to their smoother surfaces as compared to the bare ceramic membrane and their antimicrobial properties. Among the PEC samples, CMC-/PEC had the lowest cell attachment, while QC+/PEC showed the highest attachment due to electrostatic attraction. The ceramic and bare PEC surfaces were negligibly bactericidal, while cell viability decreased to 34.4 ± 10.2% and 30.6 ± 8.2% with the CMC-/PEC and QC+/PEC surfaces, respectively. In the filtration experiments, the unmodified PEC and CMC-/PEC showed lower rates of flux decline due to organic fouling than did the bare ceramic or QC+/PEC due to electrostatic repulsion. Furthermore, PECs as protective layers promoted much higher flux recoveries than simply backwashing the uncoated membranes. This surface tunability, then, enhances the potential of PECs either as fouling resistant materials or as a method to create a sacrificial, protective layer on surfaces that once fouled can be dissolved and re-established.

Probing protein rejection behavior of blended PES-based flat-sheet ultrafiltration membranes: A density functional theory (DFT) study

Membrane fouling is a common problem in membrane technology and causes detrimental effects for the applied membranes such as loss of integrity and productivity. Henceforward, we devoted this work to fabricate membranes that pose favored criteria in the direction of alleviating membrane fouling incidence. Herein, the fabricated membranes were traced via an assortment of both experimental and molecular modeling verifications to understand the mechanism of interaction. To do so, firstly, three different ultrafiltration (UF) membranes had been prepared via facile wet phase inversion method thru dipping a casting solution composed of polyethersulfone-polyvinyl pyrrolidone (PES-PVP) and polyethersulfone-Pluronic P31R1 (PES-P31R1) in a water coagulation bath. Regarding the practical-based data, the pristine PES membrane exhibited the highest rejection of bovine serum albumin (BSA) protein (model foulant) compared with the modified PES-based membranes. The membrane chemical compositions were elucidated with ATR-FTIR Spectroscopy. On the other hand, molecular modeling has been carried out via calculating thermodynamic parameters, level parametric method, and density functional theory (DFT). Thermodynamic parameters analysis indicated that the noticeable difference of BSA rejection may be ascribed to different entropy behavior for the fabricated membranes. In addition, the level parametric method (PM6) and density functional theory DFT: B3LYP with 6-31g (d,p) basis set models clarified the interaction manner of BSA molecules to membrane surfaces.

Antifouling and antibacterial evaluation of ZnO/MWCNT dual nanofiller polyethersulfone mixed matrix membrane

The aim of this study is to evaluate the performance and antifouling properties of polyethersulfone (PES) membrane incorporated with dual nanofiller, zinc oxide (ZnO) and multi-walled carbon nanotube (MWCNT). The synergistic effect of the these nanofillers in PES membrane is studied by blending different ratio of ZnO/MWCNT nanofiller into the PES membrane. The fabricated membranes were characterized in terms of cross-section and surface morphology, surface hydrophilicity, pore size and porosity. The filtration performance of the membranes was tested using 50 mg/L humic acid (HA) solution as model solution. SEM image and gravimetric evaluation reported that the incorporation of both MWCNT and ZnO into the PES membrane improved porosity significantly up to 46.02%. Lower water contact angle of PES membrane incorporated with equal ratio of MWCNT and ZnO (PES 3) revealed that it has neat PES membrane properties and more hydrophilic membrane surface than single filler. PES 3 outperform other membranes with excellent HA permeate flux of 40.00 L/m².h and rejection of 88.51%. Due to hydrophilic membrane surface, PES 3 membrane demonstrate efficient antifouling properties with lower relative flux reduction (RFR) and higher flux recovery ratio (FRR). PES 3 also showed notable antibacterial properties with less bacterial attached to the membrane compared to neat PES membrane (PES 0).

Versatile and High-Throughput Polyelectrolyte Complex Membranes via Phase Inversion

High-flux filtration membranes constructed through scalable and sustainable methods are desirable for energy-efficient separations. Often, these criteria are difficult to be reconciled with one another. Polymeric membranes can provide high flux but frequently involve organic solvents in processing steps. Solubility of many polymeric membranes in organic media also restricts their implementation in solvent filtration. In the present work, we report a simple and high-throughput aqueous processing approach for polyelectrolyte complex (PEC) membranes with controllable porosity and stability in various aqueous and organic environments. PECs are materials composed of oppositely charged polymer chains that can form solids in aqueous environments, yet which can be dissolved in very specific salt solutions capable of breaking the interpolymer ion pairs. By exploiting the salt-induced dissolution and subsequent reformation of the complex, nano- to microporous films are rapidly synthesized which resemble membranes obtained through conventional solvent-phase inversion techniques. PECs remain stable in organic solvents because of the low dielectric constant of the environment, which enhances electrostatic interactions, making them suitable for a wide range of water and solvent filtration applications. Here, we elucidate how the polymer-phase behavior can be manipulated to exercise morphological control, test membrane performance for water and solvent filtration, and quantify the mechanical stability of PECs in relevant conditions.

The Effect of Ca and Mg Ions on the Filtration Profile of Sodium Alginate Solution in a Polyethersulfone-2-(methacryloyloxy) Ethyl Phosphorylchloline Membrane

The efforts to improve the stability of membrane filtration in applications for wastewater treatment or the purification of drinking water still dominate the research in the field of membrane technology. Various factors that cause membrane fouling have been explored to find the solution for improving the stability of the filtration and prolong membrane lifetime. The present work explains the filtration performance of a hollow fiber membrane that is fabricated from polyethersulfone-2-(methacryloyloxy) ethyl phosphorylchloline while using a sodium alginate (SA) feed solution. The filtration process is designed in a pressure driven cross-flow module using a single piece hollow fiber membrane in a flow of outside-inside We investigate the effect of Ca and Mg ions in SA solution on the relative permeability, membrane resistance, cake resistance, and cake formation on the membrane surface. Furthermore, the performance of membrane filtration is predicted while using mathematical models that were developed based on Darcy’s law. Results show that the presence of Ca ions in SA solution has the most prominent effect on the formation of a cake layer. The formed cake layer has a significant effect in lowering relative permeability. The developed models have a good fit with the experimental data for pure water filtration with R2 values between 0.9200 and 0.9999. When treating SA solutions, the developed models fit well with experimental with the best model (Model I) shows R2 of 0.9998, 0.9999, and 0.9994 for SA, SA + Ca, and SA + Mg feeds, respectively.

Removal of bovine serum albumin from wastewater using fouling resistant ultrafiltration membranes based on the blends of cellulose acetate, and PVP-TiO2 nanoparticles

Fouling resistant ultrafiltration membranes based on the blends of polyvinylpyrrolidone (PVP), TiO₂ nanoparticles and cellulose acetate, CA-PVP-TiO₂ (CATP), for removal of bovine serum albumin (BSA) were prepared by using phase inversion process. The influences of PVP and TiO₂ on the preparation of phase inverted cellulose acetate (CA) ultrafiltration membrane were explored in terms of morphology study, equilibrium water content (EWC), hydraulic resistance, permeability performance, hydrophilicity, and thermal stability. After the introduction of PVP and TiO₂ to the ternary (polymer-solvent-non-solvent) system, the formations of finger-like structures and macro-voids were reduced significantly. An improvement in porosity, average pore size, and hydrophilic nature of the CA membranes were detected after the introduction of PVP and TiO₂ into the polymer matrix. The interaction between TiO₂ and CA was confirmed and the degradation temperature of the CA membrane was significantly improved. BSA protein removal efficiency, anti-fouling performance, and recycling potential of the UF membranes were investigated. The CATP membrane (10.5 wt % CA: 4 wt % PVP: 2 wt % TiO₂) has displayed high BSA removal efficiency and flux recovery ratios (NFR) with enhanced anti-fouling performances for the three fouling/rinsing cycles.

Development of Hybrid Ultrafiltration Membranes with Improved Water Separation Properties Using Modified Superhydrophilic Metal-Organic Framework Nanoparticles

Metal-organic frameworks (MOFs) are being intensively explored as filler materials for polymeric membranes primarily due to their high polymer affinity, large pore volumes, and alterable pore functionalities, but the development of MOF-based ultrafiltration (UF) membranes for water treatment lags behind. Herein, poly(sulfobetaine methacrylate) (PSBMA)-functionalized MOF UiO-66-PSBMA was developed, and incorporated into polysulfone (PSf) casting solution to fabricate novel hybrid UF membranes via phase-inversion method. The resultant UiO-66-PSBMA/PSf membrane exhibited significantly improved water flux (up to 602 L m^-2 h^-1), which was 2.5 times that of the pristine PSf membrane (240 L m^-2 h^-1) and 2 times that of UiO-66-NH₂/PSf membrane (294 L m^-2 h^-1), whereas the rejection of UiO-66-PSBMA/PSf membrane was still maintained at a high level. Moreover, UiO-66-PSBMA/PSf membrane exhibited improved antifouling performance. The improvement of membrane performances could be attributed to the well-tailored properties of UiO-66-PSBMA. On one hand, the excellent dispersion and compatibility of UiO-66-PSBMA ensured the formation of a uniform structure with few defects. On the other hand, the superhydrophilicity of UiO-66-PSBMA could accelerate the exchange rate between solvent and nonsolvent, resulting in a more hydrophilic surface and a more porous structure. Besides, UiO-66-PSBMA nanoparticles in the thin layer provided additional flow paths for water permeation through their hydrophilic porous structure as well as the tiny interspace between PSf matrix. This study indicates the great application potential of UiO-66-PSBMA in fabricating hybrid UF membranes and provides a useful guideline to integrate other modified hydrophilic MOFs to design UF membranes for water treatment.