Poly(Allylamine Hydrochloride) and ZnO Nanohybrid Coating for the Development of Hydrophobic, Antibacterial, and Biocompatible Textiles.

In healthcare facilities, infections caused by Staphylococcus aureus (S. aureus) from textile materials are a cause for concern, and nanomaterials are one of the solutions; however, their impact on safety and biocompatibility with the human body must not be neglected. This study aimed to develop a novel multilayer coating with poly(allylamine hydrochloride) (PAH) and immobilized ZnO nanoparticles (ZnO NPs) to make efficient antibacterial and biocompatible cotton, polyester, and nylon textiles. For this purpose, the coated textiles were characterized with profilometry, contact angles, and electrokinetic analyzer measurements. The ZnO NPs on the textiles were analyzed by scanning electron microscopy and inductively coupled plasma mass spectrometry. The antibacterial tests were conducted with S. aureus and biocompatibility with immortalized human keratinocyte cells. The results demonstrated successful PAH/ZnO coating formation on the textiles, demonstrating weak hydrophobic properties. Furthermore, PAH multilayers caused complete ZnO NP immobilization on the coated textiles. All coated textiles showed strong growth inhibition (2-3-log reduction) in planktonic and adhered S. aureus cells. The bacterial viability was reduced by more than 99%. Cotton, due to its better ZnO NP adherence, demonstrated a slightly higher antibacterial performance than polyester and nylon. The coating procedure enables the binding of ZnO NPs in an amount (<30 µg cm-2) that, after complete dissolution, is significantly below the concentration causing cytotoxicity (10 µg mL-1).

Antibacterial evaluation of different prosthetic liner textiles coated by CuO nanoparticles.

Prosthetic liners are mainly used as an interface between residual limbs and prosthetic sockets to minimize physical and biological damage to soft tissue. However, the closed and moist conditions within liners and the amputee's skin provide a suitable environment for bacterial growth to cause infections. This study aimed to coat a comprehensive variant material with copper oxide nanoparticles (CuO NPs) and compare their surface analysis and antibacterial properties. These materials were covered with CuO NPs solution at a concentration of 70 µg mL-1 to achieve this purpose. After drying, their surface characteristics were analyzed by measuring zeta potential, contact angle, surface roughness, and fiber arrangement. Cu-released concentration from the coatings into the acetate buffer solution by inductively coupled plasma mass spectrometry indicated that lycra and nylon quickly released Cu ions to concentrations up to ∼0.2 µg mL-1 after 24 h, causing low metabolic activity of human bone-marrow mesenchymal stem cells (bMSC) in the indirect assay. Antibacterial activity of the coated specimens was evaluated by infecting their surfaces with the Gram-positive bacteria Staphylococcus epidermidis, reporting a significant ∼40 % reduction of metabolic activity for x-dry after 24 h; in addition, the number of viable bacterial colonies adhered to the surface of this material was reduced by ∼23 times in comparison with non-treated x-dry that were visually confirmed by scanning electron microscope. In conclusion, CuO NPs x-dry shows optimistic results to pursue further experiments due to its slow speed of Cu release and prolonged antibacterial activity, as well as its compatibility with human cells.

Utilisation of waste Cu-, Mn- and Fe-loaded zeolites generated after wastewater treatment as catalysts for air treatment.

Disposal of copper, manganese and iron is particularly problematic in wastewater of metallurgical and galvanization plants, the electronics industry and agriculture. On the other hand, volatile organic compounds (VOCs), emitted from industrial processes, transportation and consumer products are the main class of air pollutants. The study revealed the potential of waste metal-loaded zeolite, generated through wastewater treatment procedures, to be utilised as an effective VOC removal catalyst for air treatment. In the first step, we have evaluated the sorption performance of natural zeolite clinoptilolite (HEU type), and synthetic zeolite 4A (LTA type) for the simultaneous removal of Cu2+, Mn2+ and Fe3+ species from aqueous solution. By a detailed sorption study, we determined the optimum sorption conditions and maximum metal concentrations in wastewater that can be after treatment disposed of in rivers or municipal plants. The efficiency of both zeolites for metal immobilization was demonstrated for concentrations up to 5 mg metals/1 g zeolite. These waste Cu-, Mn- and Fe-loaded zeolites were thermally treated at 540 °C before the second step, where we evaluated their catalytic performance in removing VOC. The thermally treated waste Cu-, Mn- and Fe-loaded natural zeolite clinoptilolite showed good catalytic performance in total toluene oxidation as a model VOC (conversion rate up to 96% at 510°C) and cycling stability (less than 15% drop in conversion rate in 4 h). In contrast, this is not the case for thermally treated waste Cu-, Mn- and Fe-loaded synthetic zeolite 4A.

Correlating Structural Properties with Electrochemical Behavior of Non-graphitizable Carbons in Na-Ion Batteries.

We report on a detailed structural versus electrochemical property investigation of the corncob-derived non-graphitizable carbons prepared at different carbonization temperatures using a combination of structural characterization methodology unique to this field. Non-graphitizable carbons are currently the most viable option for the negative electrode in sodium-ion batteries. However, many challenges arise from the strong dependence of the precursor's choice and carbonization parameters on the evolution of the carbon matrix and its resulting electrochemistry. We followed structure development upon the increase in carbonization temperature with thorough structural characterization and electrochemical testing. With the increase of carbonization temperature from 900 to 1600 °C, our prepared materials exhibited a trend toward increasing structural order, an increase in the specific surface area of micropores, the development of ultramicroporosity, and an increase in conductivity. This was clearly demonstrated by a synergy of small- and wide-angle X-ray scattering, scanning transmission electron microscopy, and electron-energy loss spectroscopy techniques. Three-electrode full cell measurements confirmed incomplete desodiation of Na+ ions from the non-graphitizable carbons in the first cycle due to the formation of a solid-electrolyte interface and Na trapping in the pores, followed by a stable second cycle. The study of cycling stability over 100 cycles in a half-cell configuration confirmed the observed high irreversible capacity in the first cycle, which stabilized to a slow decrease afterward, with the Coulombic efficiency reaching 99% after 30 cycles and then stabilizing between 99.3 and 99.5%. Subsequently, a strong correlation between the determined structural properties and the electrochemical behavior was established.

Bio-Based Epoxy Adhesives with Lignin-Based Aromatic Monophenols Replacing Bisphenol A.

A bio-epoxy surface adhesive for adherence of the metal component species to glass substrate with desirable adhesion strength, converted controlled removal upon request, and bio-based resource inclusion was developed. For the development of resin, three different lignin-based aromatic monophenols, guaiacol, cresol, and vanillin, were used in the chemical epoxidation reaction with epichlorohydrin. The forming transformation process was studied by viscoelasticity, in situ FTIR monitoring, and Raman. Unlike other hydroxyl phenyls, guaiacol showed successful epoxide production, and stability at room temperature. Optimization of epoxide synthesis was conducted by varying NaOH concentration or reaction time. The obtained product was characterized by nuclear magnetic resonance and viscosity measurements. For the production of adhesive, environmentally problematic bisphenol A (BPA) epoxy was partially substituted with the environmentally acceptable, optimized guaiacol-based epoxy at 20, 50, and 80 wt.%. Mechanics, rheological properties, and the possibility of adhered phase de-application were assessed on the bio-substitutes and compared to commercially available polyepoxides or polyurethanes. Considering our aim, the sample composed of 80 wt.% bio-based epoxy/20 wt.% BPA thermoset was demonstrated to be the most suitable among those analyzed, as it was characterized by low BPA, desired boundary area and recoverability using a 10 wt.% acetic acid solution under ultrasound.

Toward the Continuous Production of Multigram Quantities of Highly Uniform Supported Metallic Nanoparticles and Their Application for Synthesis of Superior Intermetallic Pt-Alloy ORR Electrocatalysts.

A fast and facile pulse combustion (PC) method that allows for the continuous production of multigram quantities of high-metal-loaded and highly uniform supported metallic nanoparticles (SMNPs) is presented. Namely, various metal on carbon (M/C) composites have been prepared by using only three feedstock components: water, metal-salt, and the supporting material. The present approach can be elegantly utilized also for numerous other applications in electrocatalysis, heterogeneous catalysis, and sensors. In this study, the PC-prepared M/C composites were used as metal precursors for the Pt NPs deposition using double passivation with the galvanic displacement method (DP method). Lastly, by using thin-film rotating disc electrode (TF-RDE) and gas-diffusion electrode (GDE) methodologies, we show that the synergistic effects of combining PC technology with the DP method enable production of superior intermetallic Pt-M electrocatalysts with an improved oxygen reduction reaction (ORR) performance when compared to a commercial Pt-Co electrocatalyst for proton exchange membrane fuel cells (PEMFCs) application.

Evolution of Surface Catalytic Sites on Bimetal Silica-Based Fenton-Like Catalysts for Degradation of Dyes with Different Molecular Charges.

We present here important new findings on the direct synthesis of bimetal Cu-Mn containing porous silica catalyst and the effects of structure-directing agent removal from the prepared nanomaterial on the evolution of surface catalytic sites. The extraction-calcination procedure of the structure-directing agent removal led to the formation of Cu and Mn oxo-clusters and Cu and Mn oxide nanoparticles smaller than 5 nm, while the solely calcination procedure led to the mentioned species and in addition to the appearance of CuO nanoparticles 20 nm in size. Catalysts were tested in the Fenton-like catalytic degradation of dyes with different molecular charge (cationic, anionic, and zwitterionic) as model organic pollutants in wastewater at neutral pH. Significantly faster degradation of cationic and anionic dyes in the first 60 min was observed with the catalyst containing larger CuO nanoparticles (>20 nm) due to the less hindered generation of •OH radicals and slower obstructing of the active sites on the catalysts surface by intermediates. However, this was not found beneficial for zwitterionic dye with no adsorption on the catalysts surface, where the catalyst with smaller Cu species performed better.

Characterization of Polyamide 6/Multilayer Graphene Nanoplatelet Composite Textile Filaments Obtained Via In Situ Polymerization and Melt Spinning.

Studies of the production of fiber-forming polyamide 6 (PA6)/graphene composite material and melt-spun textile fibers are scarce, but research to date reveals that achieving the high dispersion state of graphene is the main challenge to nanocomposite production. Considering the significant progress made in the industrial mass production of graphene nanoplatelets (GnPs), this study explored the feasibility of production of PA6/GnPs composite fibers using the commercially available few-layer GnPs. To this aim, the GnPs were pre-dispersed in molten ε-caprolactam at concentrations equal to 1 and 2 wt %, and incorporated into the PA6 matrix by the in situ water-catalyzed ring-opening polymerization of ε-caprolactam, which was followed by melt spinning. The results showed that the incorporated GnPs did not markedly influence the melting temperature of PA6 but affected the crystallization temperature, fiber bulk structure, crystallinity, and mechanical properties. Furthermore, GnPs increased the PA6 complex viscosity, which resulted in the need to adjust the parameters of melt spinning to enable continuous filament production. Although the incorporation of GnPs did not provide a reinforcing effect of PA6 fibers and reduced fiber tensile properties, the thermal stability of the PA6 fiber increased. The increased melt viscosity and graphene anti-dripping properties postponed melt dripping in the vertical flame spread test, which consequently prolonged burning within the samples.