Polyvinylpyrrolidone - Reduced Graphene Oxide - Pd Nanoparticles as an Efficient Nanocomposite for Catalysis Applications in Cross-Coupling Reactions

This paper reported a scientific approach adopting microwave-assisted synthesis as a synthetic route for preparing highly active palladium nanoparticles stabilized by polyvinylpyrrolidone (Pd/PVP) and supported on reduced Graphene oxide (rGO) as a highly active catalyst used for Suzuki, Heck, and Sonogashira cross coupling reactions with remarkable turnover number (6500) and turnover frequency of 78000 h-1. Pd/PVP nanoparticles supported on reduced Graphene oxide nanosheets (Pd-PVP/rGO) showed an outstanding performance through high catalytic activity towards cross coupling reactions. A simple, reproducible, and reliable method was used to prepare this efficient catalyst using microwave irradiation synthetic conditions. The synthesis approach requires simultaneous reduction of palladium and in the presence of Gaphene oxide (GO) nanosheets using ethylene glycol as a solvent and also as a strong reducing agent. The highly active and recyclable catalyst has so many advantages including the use of mild reaction conditions, short reaction times in an environmentally benign solvent system. Moreover, the prepared catalyst could be recycled for up to five times with nearly the same high catalytic activity. Furthermore, the high catalytic activity and recyclability of the prepared catalyst are due to the strong catalyst-support interaction. The defect sites in the reduced Graphene oxide (rGO) act as nucleation centers that enable anchoring of both Pd/PVP nanoparticles and hence, minimize the possibility of agglomeration which leads to a severe decrease in the catalytic activity.

Optimization Of The Catalytic Performance Of Pd/Fe 3 O 4 Nanoparticles Prepared Via Microwave-assisted Synthesis For Pharmaceutical And Catalysis Applications

Microwave assisted synthesis technique was used to prepare palladium supported on iron oxide nanoparticles. The advantage of using microwave irradiation as a synthetic tool is due to its unique features as a one step, simple, versatile, and rapid process. The reactants are added simply at room temperature without using high-temperature injection. Hydrazine hydrate was added by the following ratios (0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1, 1.6, and 3) ml to the different prepared samples at room temperature in order to investigate its effect on the catalytic performance of the prepared catalysts. The prepared catalyst could be used as an ideal candidate not only for pharmaceutical industry through cross-coupling reactions but also for low temperature oxidation catalysis of carbon monoxide and pharmaceutical applications as well. The experimental results showed that Pd/Fe3O4 catalyst has a remarkable catalytic activity for carbon monoxide oxidation catalysis due to the strong interaction between palladium and iron oxide nanoparticles. This may be due to the small particle size (7-14 nm) and concentration ratio of the Pd nanoparticles dispersed on the surface of magnetite (Fe3O4). Those nanoparticles were characterized by various spectroscopic techniques including; X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Vibrating Sample Magnetometer (VSM) and transmission electron microscopy (TEM)

Facile Synthesis Of Reduced Graphene Oxide-supported Pd/Cuo Nanoparticles As An Efficient Catalyst For Cross-coupling Reactions

The present communication reports a scientific investigation of a simple and versatile synthetic route for the synthesis of palladium nanoparticles decorated with copper oxide and supported on reduced graphene oxide (rGO). They are used as a highly active catalyst of Suzuki, Heck, and Sonogashira cross coupling reactions with a remarkable turnover number of 7000 and a turnover frequency of 85000 h-1. The Pd-CuO nanoparticles supported on reduced graphene oxide nanosheets (Pd-CuO/rGO) exhibit an outstanding performance through a high catalytic activity towards cross coupling reactions. A simple, reproducible, and reliable method is used to prepare this efficient catalyst using microwave irradiation synthetic conditions. The synthesis approach requires a simultaneous reduction of palladium and copper nitrates in presence of graphene oxide (GO) nanosheets using hydrazine hydrate as a strong reducing agent. The highly active and recyclable catalyst has many advantages including mild reaction conditions and short reaction durations in an environmentally benign solvent system. Moreover, the catalyst prepared can be recycled for up to five times with nearly identical high catalytic activity. Furthermore, the high catalytic activity and the recyclability of the catalyst prepared are due to the strong catalyst-support interaction. The defect sites of the reduced graphene oxide (rGO) act as nucleation centers that enable anchoring of both Pd and CuO nanoparticles and hence, minimize the possibility of agglomeration which leads to a severe decrease of the catalytic activity

Microwave-assisted Synthesis Of Palladium Nanoparticles Supported On Copper Oxide In Aqueous Medium As An Efficient Catalyst For Suzuki Cross-coupling Reaction

We report here a reliable green method for the synthesis of palladium nanoparticles supported on copper oxide as a highly active and efficient catalyst for Suzuki cross-coupling reaction. The experimental synthetic approach is based on microwave-assisted chemical reduction of an aqueous mixture of palladium and copper salt simultaneously using hydrazine hydrate as reducing agent. The catalyst was fully characterized using various techniques showing well-dispersed palladium nanoparticles. The catalytic activity and recyclability of the prepared catalyst were experimentally explored in the ligand-free Suzuki cross-coupling reaction with a diverse series of functionalized substrates. The synthesized Pd/CuO catalyst shows many advantages beside its high catalytic efficiency such as the recyclability of up to five times with negligible loss of catalytic activity, short reaction times, use of environmentally benign solvent systems, and mild reaction conditions

Hydrothermal Synthesis Of Graphene Supported Pd/Fe 3 O 4 Nanoparticles As Efficient Magnetic Catalysts For Suzuki Cross – Coupling

This research reports a reproducible, reliable, and efficient method for preparing palladium nanoparticles dispersed on a composite of Fe3O4 and graphene as an active catalyst with high efficiency for being used in Suzuki cross – coupling reactions. Graphene supported Pd/Fe3O4 nanoparticles (Pd/Fe3O4 /G) exhibit a remarkable catalytic performance towards Suzuki coupling reactions. Moreover, the prepared catalyst recyclability was up to nine times without losing its high catalytic activity. The catalyst was prepared using hydrothermal synthesis; the prepared catalyst is magnetic in order to facilitate catalyst separation out of the reaction medium after reaction completion simply through using a strong magnet. This approach offers unique advantages including recyclability, mild reaction conditions, and reproducibility. Furthermore, the magnetic properties of the prepared catalyst made a huge enhancement to the ability to purify the reaction products from catalyst and other side products. The high catalytic performance and recyclability of the prepared catalyst are due to the strong interaction between the catalyst and the support. Moreover, the reduced GO nanosheets have defect sites acting as nucleation centers to anchor the Pd and Fe3O4 nanoparticles and hence minimize the harmful effect of potential agglomeration and subsequently the anticipated decrease in the catalyst catalytic activity as a direct impact for this unfavorable agglomeration

Equilibrium And Kinetic Study On The Biosorption Of Trypan Blue From Aqueous Solutions Using Avocado Seed Powder

This research aims to investigate the removal of trypan blue dye from aqueous solutions by employing ground avocado seeds powder, a low-cost biowaste adsorbent (biosorbent), under various experimental conditions. The effect of contact time, initial dye concentration, and adsorbent dose on dye removal were studied. The experimental kinetic data were fitted to pseudo-first order and pseudo-second-order kinetic models. Results imply that adsorption of trypan blue on the avocado seed adsorbent nicely followed the pseudo-second-order kinetic model. Equilibrium isotherms were analyzed by Langmuir and Freundlich isotherms, where Langmuir isotherm described the isotherm data with a high-correlation coefficient (R2=0.9948) closer to unity, and maximum adsorption capacity was found to be 19.3 mg g−1. The present study results substantiate that ground avocado seeds are a promising adsorbent for the removal of the dye trypan blue from industrial wastewater

Effects of light intensity on Orthosiphon stamineus Benth. seedlings treated with different organic fertilizers.

The main objective of this study was to investigate the effects of varying light intensities and different organic fertilizers on the growth performance of O. stamineus seedlings through measurement of Relative Height Growth Rate (RHGR) and biomass production. Randomized Complete Block Design (RCBD) was used. Orthosiphon stamineus was arranged accordingly into three blocks or replicates. The three blocks represented the percentage light intensity. Block 1 (30% of light), Block 2 (50% of light) and Block 3 (100% of light). Each Block had four treatments and 25 plants of O. stamineus. The treatments were chicken dung, cow dung, oil palm empty fruit bunch (EFB) and control. The four treatments were arranged randomly in each block. Growth parameters measured were plant height, biomass (aerial portion, root biomass and total biomass within sixth month’s period. The 50% Relative Light Intensity (RLI) was better than 30 and 100% RLI. The chicken dung is better than oil palm EFB and cow dung

Fourier transform infrared spectroscopy as a novel approach for analyzing the biochemical effects of anionic surfactants on a surfactant-degrading acrobacter butzleri strain

Cataloged from PDF version of article.Anionic surfactant-biodegrading capability of an Arcobacter butzleri strain was analyzed under aerobic conditions. The A. butzleri isolate displayed efficient surfactant-biodegrading capacity for sodium dodecyl sulfate (SDS) at concentrations of up to 100 mg/L in 6 days, corresponding to 99.0% removal efficiency. Fourier transform infrared spectroscopy was applied to observe the effects of varying concentrations of SDS on the biochemistry of bacterial cells. Results suggest that protein secondary structures were altered in bacterial cells at sufficiently high SDS concentrations, concurrent with SDS biodegradation

Removal Of Methylene Blue By Adsorption Of Water Hyacinth Derived Active Carbon Embedded With Cobalt Nanoparticles

In this research, active carbon-based catalyst synthesis and characterization were tested for potential catalysts to be used in dye removal of methylene blue (MB). Water hyacinth is one of the major problems that is facing humankind and especially here in Egypt. One of the implications of industrial activities is environmental pollution. Dyes used in the production of textiles, paper, and clothes are one of the major pollutants. The waste of those dyes discharged into water supplies without treatment or with ineffective treatment harmfully impacts the environment. In this research, the treatment is implemented using active carbon-based catalysts using embedded nanoparticles. This leads to a huge increase in the adsorbent\u27s surface area, also increasing the adsorbent efficiency. The activated carbon was derived from water hyacinth that grows near the Nile River. Water hyacinth has many practical uses as it can absorb heavy metals like lead and dyes. Water hyacinth was converted into activated carbon through carbonization. Different dyes were used with different contact times in fixed conditions

Identification of Selective Inhibitors of Cancer Stem Cells by High-Throughput Screening

Screens for agents that specifically kill epithelial cancer stem cells (CSCs) have not been possible due to the rarity of these cells within tumor cell populations and their relative instability in culture. We describe here an approach to screening for agents with epithelial CSC-specific toxicity. We implemented this method in a chemical screen and discovered compounds showing selective toxicity for breast CSCs. One compound, salinomycin, reduces the proportion of CSCs by >100-fold relative to paclitaxel, a commonly used breast cancer chemotherapeutic drug. Treatment of mice with salinomycin inhibits mammary tumor growth in vivo and induces increased epithelial differentiation of tumor cells. In addition, global gene expression analyses show that salinomycin treatment results in the loss of expression of breast CSC genes previously identified by analyses of breast tissues isolated directly from patients. This study demonstrates the ability to identify agents with specific toxicity for epithelial CSCs.National Cancer Institute (U.S.). Initiative for Chemical GeneticsBreast Cancer Research FoundationRoot, DavidBroad Institute of MIT and Harvard (RNAi Platform