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

Hydrophobic Polymers Flooding

Crude oil and other petroleum products are crucial to the global economy today due to increasing energy demand approximately (~1.5%) per year and significant oil remaining after primary and secondary oil recovery (~45-55% of original oil in place, OOIP), which accelerates the development of enhanced oil recovery (EOR) technologies. Polymer flooding through hydrophobically associated polyacrylamides (HAPAM) is a widely implemented EOR-technique, so they attracted much attention on both academic and industrial scales. Hydrophobically associating polyacrylamide (HAPAM) prepared by free radical emulsion polymerization of acrylamide (AM) monomer, divinyl sulfone as hydrophobic crosslinked moiety and surfmers, to chemically anchor a surfmer and hydrophobic crosslinker moiety onto the back bone of acrylamide chain. After that, polymeric nanocomposite was prepared through copolymerization of prepared HAPAM with different molar ratios of silica nanoparticles through one shot synthesis. Rheological properties for the prepared composites were evaluated. Wettability evaluation carried through quantitative and qualitative techniques where the results indicate novel polymers ability to alter rock wettability from oil-wet to water- wet

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

Functionalized magnetic bentonite-iron oxide nanocomposite and its application to decrease scale formation in tubing of oil/gas production

This study reports the development of 3-aminopropyltriethoxysilane (APTES) functionalized magnetic bentonite (AMB) nanocomposite by microwave assisted route to adsorb and decrease Ba(II) and Sr(II) ions, which are responsible for scale formation in the tubing of gas and oil production. Phases, function groups, morphology and magnetic properties was investigated for the prepared samples as well as porosity and surface area. Adsorption results obtained at different temperatures shows that the adsorption process of the prepared AMB is exothermic and follows Langmuir adsorption isotherm model. Kinetics of the adsorption processes at AMB surface was investigated. The process was found to follow the pseudo-second order kinetic model. pH of the system has a great influence on the adsorption of both ions. At pH 9, maximum adsorption was achieved, 124.8 mg/g and 120.0 mg/g for strontium and barium ions, respectively. While it was 107.7 mg/g and 86.7 mg/g for strontium and barium, respectively, at pH 7 similar to produced water pH. AMB showed good removal efficiency that reached 41% and 76.2% for Ba(II) and Sr(II), respectively. Based on the experimental results, AMB is a good natural low-cost material that can be used to decrease scale formation in tubing of oil/gas production

Selective nano alumina supported vanadium oxide catalysts for oxidative dehydrogenation of ethylbenzene to styrene using CO2 as soft oxidant

Nano alumina-supported V2O5 catalysts with different loadings have been tested for the dehydrogenation of ethylbenzene with CO2 as an oxidant. High surface area nano-alumina was prepared and used as support for V2O5 as the catalyst. The catalysts were synthesized by impregnation techniques followed by calcinations and microwave treatment, denoted as V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW, respectively. The V2O5 loading was varied on nano-alumina from 5 to 30 wt%. The support and catalysts were characterized by X-ray diffraction (XRD), Barett–Joyner–Halenda (BJH) pore-size distribution, N2-adsorption isotherms, Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and temperature programed desorption (TPD-NH3). The characterization results indicated that V2O5 is highly dispersed on alumina up to 30%-V2O5/γ-Al2O3-MW prepared by MW method. The TPD studies indicated that there are significant differences in acid amount and strength for V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW-catalysts. The catalytic activity of the prepared catalysts was evaluated in the temperature range 450–600 °C in relation to the physicochemical properties and surface acidity. The results revealed that optimum catalytic activity and selectivity (∼100%) toward styrene production were obtained using 10% V2O5/γ-Al2O3-MW catalyst treated with microwave

Hydrophobically associated polymers for wettability alteration and enhanced oil recovery – Article review

Crude oil and other petroleum products are crucial to the global economy today due to increasing energy demand approximately (∼1.5%) per year and significant oil remaining after primary and secondary oil recovery (∼45–55% of original oil in place, OOIP), which accelerates the development of enhanced oil recovery (EOR) technologies to maximize the recovered oil amount by non-conventional methods as polymer flooding. This review discusses enhanced oil recovery methods specially polymer flooding techniques and their effects on rock wettability alteration