In vitro assessment of activity of graphene silver composite sheets against multidrug-resistant bacteria and Tomato Bushy Stunt Virus

Purpose: To synthesize graphene-based silver nanocomposites and evaluate their antimicrobial and anti-Tomato Bushy Stunt Virus (TBSV) activities.Methods: A graphene-based silver composite was prepared by adsorbing silver nanoparticles AgNPs to the surfaces of graphene oxide (GO) sheets. Scanning electron microscopy was used to analyze the morphology of the synthesized graphene-based silver nanocomposite. This compound was investigated for its antimicrobial activity against several multidrug-resistant human pathogens using the agar well diffusion technique. Moreover, the biocompatibility and antiviral activity of the graphene-based nanocomposite against TBSV was studied in lettuce.Results: The graphene-based silver composite exhibited remarkable antimicrobial effects against pathogenic bacteria including Shigella sonnei and Pseudomonas aeruginosa with zones of inhibition of 32 ± 0.11 and 29 ± 0.05 mm, respectively. They inhibited TBSV better than graphene and GO.Conclusion: The synthesized graphene-based silver composite exhibits potent activity against TBSV and multidrug resistant bacteria, indicating that they are good candidates for future therapeutic applications.Keywords: Graphene oxide, Graphene-based nanocomposite, Antiviral, Antimicrobial, Multidrugresistant (MDR) human pathogen

The performance of chemically and physically modified local kaolinite in methanol dehydration to dimethyl ether

The catalytic activity of modified natural kaolinite as a solid acid catalyst for dimethyl ether (DME) preparation was investigated by following up the conversion% of methanol and the yield% of DME. Natural kaolinite (KN) was treated chemically with H2O2 (KT) followed by thermal treatment at 500 °C (KC) and then mechano-chemically by ball milling with and without CaSO4 (KB-Ca and KB, respectively). These samples were characterized by XRD, FTIR, SEM, HRTEM, TGA and NH3-TPD techniques. The different techniques showed that the chemical treatment of kaolinite with H2O2 resulted in partial exfoliation/delamination of kaolinite, decreased the amount of acidic sites which is accompanied by increasing their strength. Calcination only decreased the acidic strength and slightly enlarged the particle size mostly due to heat effect. Ball milling resulted in multitude randomly-oriented crystals and increased the amount of acidic sites with the same strength of KT sample. CaSO4 mostly produced ordered monocrystalline kaolinite and created new acidic sites with slightly lower strength relative to KB. The catalytic activity and selectivity depend on the reaction temperature, the space velocity and the strength of acid sites. The most active sample is KB-Ca, which gives 84% DME due to its high amount and strength of acidic sites. The different modification methods resulted in 100% selectivity for DME

Synthesis and thermal properties of nanocomposites based on exfoliated organoclay polystyrene and poly(methylmethacrylate)

Exfoliated organoclay-polystyrene (OC-PS) and organoclay-poly(methyl methacrylate) (OC-PMMA) nanocomposites were prepared using novel modified/clay-polymer through both bulk polymerization and solution techniques. The synthesis was achieved by formation of derivative vinylbenzyl ammonium salt intercalated with montmorillonite (MMT) clay. The clay-vinyl/monomer was dispersed in PS or MMA monomers followed by solution polymerization. The clay-PS and clay-PMMA were used as highly compatibilizer organoclay to produce highly exfoliated nanocomposites. Morphological structure of the nanocomposites was investigated by SEM and XRD which confirmed that the clay is homogenously dispersed and exfoliated in the polymer matrixes with interlayer spacing at least of d001-value ≥4 nm for both PS and PMMA. Thermal properties of the nanocomposites show an increase in the decomposition temperature comparing to neat polymer

Oxidative desulfurization using graphene and its composites for fuel containing thiophene and its derivatives: An update review

Oxidative desulfurization, in which the aromatic sulfur containing compounds are oxidized to their analogical sulfones and subsequently extracted, has assured to be one of the exceedingly effective desulfurization processes for resulting ultra-low sulfur import fuels. The oxidative desulfurization process using graphene oxide has attracted significant interest for sulfur removal from fuels. In this survey, we discussed systematically the techniques of desulfurizations in catalytic oxidation, including the role of graphene as a supported catalyst, the research results of oxidative desulfurization using graphene oxide and provided the factors affecting the desulfurization process. We also debate the challenges counterattack the use of graphene oxide in this view, including their preparation methods and their efficiency and stability as a supported catalyst. Also, there are some of the desulfurization processes currently under investigation such as oxidation, biodesulfurization, and adsorption was outlined in brief. The combustion of fossil fuels containing sulfur compounds emits some of the sulfur oxides which considered a harmful influence on human health and the surrounding environment as well as the economy. It can be concluded that GO remains a kind of ideal supported catalysts to recognize a pure fuel in the near futurity due to their eligible physicochemical characteristics. Keywords: Oxidative desulfurization, Thiophene derivatives, Graphene, Graphene composite

Controllable Fabrication of Zn²⁺ Self-Doped TiO₂ Tubular Nanocomposite for Highly Efficient Water Treatment

Tailoring high-efficiency photocatalytic composites for various implementations is a major research topic. 1D TNTs-based nanomaterials show promise as a photocatalyst for the remediation of organic pigments in an aqueous solution. Despite this, TiO2 (TNTs) is only photoactive in the UV range due to its inherent restriction on absorption of light in the UV range. Herein, we provide a facile recipe to tailor the optical characteristics and photocatalytic activity of TNTs by incorporating Zn (II) ionic species via an ion-exchange approach in an aqueous solution. The inclusion of Zn (II) ions into the TNTs framework expands its absorption of light toward the visible light range, therefore TiO2 nanotubes shows the visible-light photo-performance. Activity performance on photocatalytic decontamination of RhB at ambient temperature demonstrates that Zn-TNTs offer considerable boosted catalytic performance compared with untreated tubular TiO2 during the illumination of visible light. RhB (10 mg L−1) degradation of around 95% was achieved at 120 min. Radical scavenger experiment demonstrated that when electron (e−) or holes (h+) scavengers are introduced to the photodegradation process, the assessment of decontamination efficacy decreased by 45% and 76%, respectively. This demonstrates a more efficient engagement of the photoexcited electrons over photogenerated holes in the photodegradation mechanism. Furthermore, there seems to be no significant decrease in the activity of the Zn-TNTs after five consecutive runs. As a result, the fabricated Zn-TNTs composite has a high economic potential in the energy and environmental domains

Synthesis and characterization of MCM-41-supported nano zirconia catalysts

Series of MCM-41 supported sulfated Zirconia (SZ) catalysts with different loadings (2.5–7.5% wt.) were prepared using direct impregnation method. The acquired solid catalysts were characterized structurally and chemically using X-RD, HRTEM, BET, FT-IR, Raman spectroscopy and TPD analysis. The acidity of the solid catalysts was investigated through cumene cracking and isopropanol dehydration at different temperatures. As the SZ loading increases, the surface acidity of the mesoporous catalysts was enhanced, this was reflected by the higher catalytic activity toward cumene cracking and isopropanol dehydration

Characterization and Catalytic Performance of Al-SBA-15 Catalyst Fabricated Using Ionic Liquids with High Aluminum Content

This study involved the fabrication of a set of aluminum ion-grafted SBA-15 utilizing ethylenediamine and trimethylamine ionic liquids. The primary objective was to examine the impact of the fabrication environment on the physicochemical characteristics of the catalysts. Comprehensive characterization of the Al-SBA-15 catalysts was conducted using various techniques, including XRD, FTIR, surface area, pyridine FTIR, 27Al-NMR, TGA, HRTEM, and FESEM, to analyze their physicochemical characteristics. Furthermore, the acidic characteristics were examined by conducting potentiometric titration in a nonaqueous solvent and employing FTIR spectroscopy to analyze the chemisorbed pyridine. The effectiveness of the fabricated acid materials was evaluated by testing their performance in acetic acid esterification with butanol. The findings obtained reveal that mesostructured SBA-15 remains intact following the successful inclusion of Al3+ ions into the silica frameworks. Additionally, a remarkable enhancement in the existence of both Bronsted and Lewis acid centers was noted due to the grafting process of Al3+ ions. At temperatures of 80 °C and 100 °C, the reaction in Al-SBA-15(T-120) proceeds swiftly, reaching approximately 32% and 38% conversion, respectively, within a span of 110 min. The excellent catalytic performance observed in the esterification reaction can be attributed to two factors: the homogeneous distribution of Al3+ ions within the SBA-15 frameworks and the acidic character of Al-SBA-15. The findings further indicate that the grafting process for incorporating Al3+ ions into the silica matrix is more efficient