Polyethersulfone Membranes Prepared with 3-Aminopropyltriethoxysilane Modified Alumina Nanoparticles for Cu(II) Removal from Water

ZIF-8/Graphene Oxide Hybrid Membranes as Breathable and Protective Barriers against Chemical Warfare Agents

Personal protective equipment against chemical warfare agents and other toxic chemicals must be protective, be breathable, and have a low thermal burden. Selectively permeable membranes are promising candidates for such equipment. In this study, a hybrid membrane consisting of a continuous and thin zeolitic imidazolate framework (ZIF)-8 layer on an oxygen-rich small-flake graphene oxide layer was produced using a simple and scalable synthesis method. The small intrinsic pores of ZIF-8 allow it to selectively separate chemicals via size exclusion while permitting water vapor to permeate out. The ZIF-8/graphene oxide membrane had high selectivity for the penetration of water vapor over nerve agent simulants (ratio of dimethyl methylphosphonate to water vapor transmittance rates of ∼312) with a high water vapor transmittance rate of 3000 g m-2 day-1. This protective barrier layer is a promising material for next-generation protective clothing with enhanced comfort and operability.

Effective cross-linking strategy for graphene oxide membrane with high structural stability and enhanced separation performance

In order to solve the poor structural stability of graphene oxide (GO) membrane, a facile and effective cross-linking technology was employed to create a high-performance GO membrane. Herein, DL-Tyrosine/amidinothiourea and (3-Aminopropyl) triethoxysilane were used to crosslink GO nanosheets and porous alumina substrate, respectively. The group evolution of GO with different cross-linking agents was detected via Fourier transform infrared spectroscopy. Ultrasonic treatment and soaking experiment were conducted to explore the structural stability of the different membranes. The GO membrane cross-linked with amidinothiourea exhibits exceptional structural stability. Meanwhile, the membrane has superior separation performance, with the pure water flux reaching approximately 109.6 l·m^-2·h^-1·bar^-1. During the treatment of 0.1 g l^-1NaCl solution, its permeation flux and rejection for NaCl are about 86.8 l·m^-2·h^-1·bar^-1and 50.8%, respectively. The long-term filtration experiment also demonstrates that the membrane exhibits great operational stability. All these indicate the cross-linking graphene oxide membrane has promising potential applications in water treatment.

Water Treatment Using High Performance Antifouling Ultrafiltration Polyether Sulfone Membranes Incorporated with Activated Carbon

Membrane fouling is a continued critical challenge for ultrafiltration membranes performance. In this work, polyether sulfone (PES) ultrafiltration (UF) membranes were fabricated via phase-inversion method by incorporating varying concentrations of APTMS modified activated carbon (mAC). The mAC was thoroughly characterized and the fabricated membranes were studied for their surface morphology, functional groups, contact angle, water retention, swelling (%) porosity, and water flux. The hydrophilicity of mAC membranes also resulted in lower contact angle and higher values of porosity, roughness, water retention as well as water flux. Also, the membranes incorporated with mAC exhibited antibacterial performance against model test strains of gram-negative Ecoil and gram-positive S. aureus. The antifouling studies based on bovine serum albumin protein (BSA) solution filtration showed that mAC membranes have better BSA flux. The higher flux and antifouling characteristics of the mAC membranes were attributed to the electrostatic repulsion of the BSA protein from the unique functional properties of AC and network structure of APTMS. The novel mAC ultrafiltration membranes developed and studied in present work can provide higher flux and less BSA rejection thus can find antifouling applications for the isolation and concentration of proteins and macromolecules.

Preparation and Characterization of Polymer Membranes Impregnated with Carbon Nanotubes for Olive Mill Wastewater

In this study, polymer membrane(s) impregnated with carbon nanotubes (CNTs) were developed, characterized and evaluated for removing phenolic compounds from olive mill wastewater; thus, protecting the environment and public health. Polyethersulfone/functionalized, multi-walled carbon nanotube (PES/fCNTs) membranes were synthesized via the phase inversion method using PES and acid-treated CNTs. The prepared membranes were then characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and contact angle. Results obtained from this study indicate a more hydrophilic surface for the prepared PES/fCNTs membranes, with a higher pure water flux compared to the polyethersulfone (PES) membranes. In addition, the amount of fCNTs in the membranes was found to be the most significant factor affecting the morphology and water flux of the membranes. The PES/fCNTs membranes at 1 bar with 0 wt.% and 1 wt.% of CNTs showed water flux of 37.8 and 69.71 kg/h.m², respectively. In addition, PES/fCNTs membranes with 0.5 wt.% fCNTs showed the highest total phenol content removal of 74%.

Re-Expression of Poly/Oligo-Sialylated Adhesion Molecules on the Surface of Tumor Cells Disrupts Their Interaction with Immune-Effector Cells and Contributes to Pathophysiological Immune Escape

Glycans linked to surface proteins are the most complex biological macromolecules that play an active role in various cellular mechanisms. This diversity is the basis of cell-cell interaction and communication, cell growth, cell migration, as well as co-stimulatory or inhibitory signaling. Our review describes the importance of neuraminic acid and its derivatives as recognition elements, which are located at the outermost positions of carbohydrate chains linked to specific glycoproteins or glycolipids. Tumor cells, especially from solid tumors, mask themselves by re-expression of hypersialylated neural cell adhesion molecule (NCAM), neuropilin-2 (NRP-2), or synaptic cell adhesion molecule 1 (SynCAM 1) in order to protect themselves against the cytotoxic attack of the also highly sialylated immune effector cells. More particularly, we focus on α-2,8-linked polysialic acid chains, which characterize carrier glycoproteins such as NCAM, NRP-2, or SynCam-1. This characteristic property correlates with an aggressive clinical phenotype and endows them with multiple roles in biological processes that underlie all steps of cancer progression, including regulation of cell-cell and/or cell-extracellular matrix interactions, as well as increased proliferation, migration, reduced apoptosis rate of tumor cells, angiogenesis, and metastasis. Specifically, re-expression of poly/oligo-sialylated adhesion molecules on the surface of tumor cells disrupts their interaction with immune-effector cells and contributes to pathophysiological immune escape. Further, sialylated glycoproteins induce immunoregulatory cytokines and growth factors through interactions with sialic acid-binding immunoglobulin-like lectins. We describe the processes, which modulate the interaction between sialylated carrier glycoproteins and their ligands, and illustrate that sialic acids could be targets of novel therapeutic strategies for treatment of cancer and immune diseases.

Green synthesis of nano-Al2O3, recent functionalization, and fabrication of synthetic or natural polymer nanocomposites: various technological applications

Environmentally friendly fabrication of nano-Al₂O₃, recent functionalization, and preparation of polymer nanocomposites including natural and man-made polymers with various industrial applications are reviewed.

Polyethersulfone membrane embedded with amine functionalized microcrystalline cellulose

In this investigation, microcrystalline cellulose (MCC) was functionalized with metformin HCl using (3-chloropropyl)triethixysilane (CPTES) as a coupling agent. Polyethersulfone (PES) membranes were incorporated with different concentrations of modified MCC (MMCC) to enhance its affinity for heavy metals during filtration of aqueous solutions. The composite membranes were characterized via fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET) method, porosity and contact angle measurements and mechanical analysis. The presence of MMCC in the host matrix was confirmed by FTIR. Although composites decomposed at lower temperatures, their thermal stability was sufficient to meet their performance requirements. DSC showed enhanced glass transition temperature (T_g) due to the interfacial interactions between membrane constituents which restrict the mobility of polymer chains. Microscopic imaging revealed higher surface roughness of composites compared to neat PES. Inclusion of MMCC increased the porosity and hydrophilicity of the membrane which consequently, higher permeability can be achieved.

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

ZSM-22/polyethersulfone membranes were prepared for salt rejection using modelled brackish water. The membranes were fabricated via direct ZSM-22 incorporation into a polymer matrix, thereby inducing the water permeability, hydrophilicity and fouling resistance of the pristine polyethersulfone (PES) membrane. A ZSM-22 zeolite material with a 60 Si/Al ratio, high crystallinity and needle-like morphologies was produced and effectively used as a nanoadditive in the development of ZSM-22/PES membranes with nominal loadings of 0–0.75 wt.%. The characterisation and membrane performance evaluation of the resulting materials with XRD, BET, FTIR, TEM, SEM and contact angle as well as dead-end cell, respectively, showed improved water permeability in comparison with the pristine PES membrane. These ZSM-22/PES membranes were found to be more effective and superior in the processing of modelled brackish water. The salt rejection of the prepared membranes for NaCl and MgCl₂ was effective, while they exhibited quite improved water flux and flux recovery ratios in the membrane permeability and anti-fouling test. This indicates that different amounts of ZSM-22 nanoadditives produce widely divergent influences on the performance of the pristine PES membrane. As such, over 55% of salt rejection is observed, which means that the obtained membranes are effective in salt removal from water.