Amount Of Ag2O Research Articles

Kamlet-Taft parameters of solvents and their relationship with methylation of hydroxy group by Ag2O

We measured the effects of Kamlet-Taft parameters on methylation of hydroxy group of N-(2-hydroxyethyl) phthalimide by Ag2O. Optimization of methylation was done by tuning the solvents, mixtures of solvents, temperature, and concentrations of primary materials (methyl iodide, methyl-d3 iodide, Ag2O). Solvents had the most effective roles on methylation by Ag2O. Although methylation did not work in polar solvents such as DMF and acetonitrile, it was successful in non-polar solvents (n-heptane, n-hexane, n-pentane, and cyclohexane). Despite using hydrocarbons was favoured for methylation, adding chloroform as a co-solvent significantly improved the yield of the reaction while using less amount of Ag2O. Kamlet-Taft parameters showed the polarizability of the solvent was the most important parameter which controlled the methylation by Ag2O.As a minor goal, subsequently, this reaction was followed by hydrolysis of N-(deuterated 2-methoxyethyl) phthalimide to prepare deuterated 2-methoxyethylamine and the target urea derivative, MTU: N-{2-[(D3) methyloxy] ethyl}-N’-1,2,3-thiadiazol-5-ylurea. Deuterium-labelled MTU will be used for isotope tracing in plant cells to shed more light on MTU localization and mode of action in plants. NMR, UV–vis, IR spectroscopies, and mass spectrometry were used to confirm the structures.

A Study the Addition of Silver Dioxide on Some Optical Properties of Phosphate Bioactive Glass

This study investigates the influence of silver oxide (Ag2O) concentration on the optical characteristics of phosphate bioactive glasses (PBGs). PBGs have emerged as promising alternatives to conventional silicate glasses in the medical field due to their excellent bioactivity and chemical resistance. Samples with varying Ag2O concentrations (0, 0.25, 0.5, and 0.75g) were sintered at 780°C for 2 hrs in an electric furnace. The samples were subjected to Fourier transfer infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and photoluminescence (PL) tests to assess their functional groups and optical properties. By analyzing the FTIR spectrum of phosphate bioactive glass containing different amounts of Ag2O, it is possible to identify changes in the vibrational modes associated with Ag-O bonds and to gain insights into the structure and composition of the material. Because Ag-O bonds exhibit infrared vibrational modes, introducing Ag2O changed the FTIR spectrum. As Ag2O concentration increased, Ag-O vibrational modes strengthened, indicating more Ag-O bonds. UV-Vis spectroscopy, with increasing Ag2O concentration, the peak location shifted towards shorter wavelengths. Optical spectra show distinct UV absorption in the prepared glass spectrum, extending to near visible with increasing Ag2O content. The PL spectra peaks and band gap energies revealed that Ag2O altered the glass's electrical structure and optical activity. These discoveries help optimize metal-phosphate bi-active glass for biomedical implants and UV-blocking coatings. The melting-annealing technique prepared glasses based on the base host Na2O-CaF2-P2O5 system with increasing Ag2O as additives or loading (0.2 to 1 wt%).

Effect of silver oxide additives on structural, optical dispersion and protection features of lead boro-phosphate glasses

This work presents the structural, optical, refractive index dispersion, and shielding properties of Ag-containing lead-boro-phosphate glasses. The glasses were prepared using the classic melt-quenching method, in which the Ag2O concentration was varied in each synthesis. The precipitation of Ag NPs was proved by the appearance of the (200) crystal plane in the XRD patterns and confirmed by the homogeneous distribution of spherical agglomerates observed in TEM images. FTIR and Raman analyses have revealed a network depolymerization process resulting from the distortion of the PO4 units and the formation of Ag NPs. Therefore, the Ag ions contribute at high concentrations to an increase in the glass density and a reduction in the optical band gap energy. Ellipsometry parameters indicate that the glass becomes more optically dispersive due to the Ag NPs formation, which improves its performance for several potential applications in multi-functional optical devices. The mass attenuation factors are determined in the energy range of 15 keV–15 MeV and are very sensitive to the silver content at low energies. The Half value layer (HVL) decreases with the amount of Ag2O, indicating the improvement in the material's ability to attenuate radiation. The results show that the glass sample with the highest Ag content has the highest shielding effectiveness.

Photocatalytic degradation of organic pollutants by Ag2O/AgSiOx

Silver silicate (AgSiOx) is a visible-driven photocatalyst. However, the efficiency of single component photocatalysts can be improved by coupling with other compounds. In this work, AgSiOx was coupled with different amounts of Ag2O using a co-precipitation method. Ratios of Ag2O:AgSiOx were controlled by varying the concentrations of Na2SiO3.9H2O and NaOH. All prepared products were characterized by X-ray diffractometry, transmission electron microscopy, X-ray photoelectron spectroscopy, surface analysis, and UV–vis diffuse reflectance spectroscopy. Under visible light irradiation, the Ag2O/AgSiOx composite could degrade rhodamine B, reactive orange, and bisphenol A solutions. The Ag2O/AgSiOx exhibited greater photocatalytic activity than AgSiOx and Ag2O because this composite improved visible light absorption and inhibited charge recombination. The Ag2O/AgSiOx prepared from 0.012 mol NaOH exhibited the highest photocatalytic activity. Photocatalytic degradation of all pollutant models to low mass species was studied by electrospray ionization mass spectrometry and the cytotoxicity of pollutant model solutions before and after photocatalytic processes was evaluated on L929 mouse fibroblast cells using the MTT assay.

Cross-Link Density, Mechanical and Thermal Properties of Chloroprene Rubber Cross-Linked with Silver(I) Oxide.

The purpose of this work was to cross-link chloroprene rubber (CR) with silver(I) oxide (Ag2O) and to investigate the properties of the obtained vulcanizates. Silver(I) oxide was chosen as an alternative to zinc oxide (ZnO), which is part of the standard CR cross-linking system. The obtained results show that it is possible to cross-link chloroprene rubber with silver(I) oxide. This is evidenced by the determined vulcametric parameters, equilibrium swelling and elasticity constants. As the Ag2O content in the composition increases, the cross-link density of the vulcanizates also increases. However, the use of 1 phr of Ag2O is insufficient to obtain a suitably extensive network. Exclusively, the incorporation of 2 phr of Ag2O results in obtaining vulcanizates with great cross-link density. The obtained compositions are characterized by good mechanical properties, as evidenced by high tensile strength. The performed thermal analyses—differential scanning calorimetry (DSC) and thermogravimetry (TGA) allowed us to determine the course of composition cross-linking, but also to determine changes in their properties during heating. The results of the thermal analysis confirmed that CR can be cross-linked with Ag2O, and the increasing amount of oxide in the composition increases the degree of cross-linking of vulcanizates. However, the amount of Ag2O in the composition does not affect the processes occurring in the heated vulcanizate.

Synthesis and characterization of AgPd alloy coatings as beneficial catalysts for low temperature fuel cells application

The Ag, Pd and AgPd alloys of different morphologies and compositions were electrodeposited onto Au and glassy carbon (GC) disc electrodes from the solution containing 0.001 M PdCl2 + 0.04 M AgCl + 0.1 M HCl + 12 M LiCl under the conditions of non-stationary (RPM = 0, samples AgPd1 and AgPd2) and convective diffusion (RPM = 1000, sample AgPd3). Electrodeposited alloy layers were characterized by the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Oxygen reduction reaction (ORR) was investigated on all coatings in 0.1 M NaOH solution saturated with oxygen. The j-E curves for the ORR were recorded by two procedures: (1) samples were cycled with 5 mV s−1 from open circuit potential (OCP) to −0.8 V for Ag and AgPd alloys (or −0.6 V for pure Pd) and back; (2) samples were cycled with 5 mV s−1 from open circuit potential to 0.45 V (formation of Ag2O, in the case of Pd formation of PdO and PdO2), from 0.45 V to −0.60 V and back to the OCP. Significant catalytic activity for the Ag and AgPd alloys was detected after cycling electrodes in the potential region of Ag2O formation and reduction. Increase of the catalytic activity for AgPd alloys was, for the first time in the literature, ascribed to the presence of a certain amount of Ag2O which could not be completely reduced during the reverse sweep from 0.45 V to −0.6 V. Catalytic activity of AgPd alloys was found to be closely related to the amount of non-reduced Ag2O (most probably in the form of Ag-hydroxide). In the absence of such treatment, the catalytic activity for the ORR on electrodeposited Ag and AgPd alloy coatings was not detected.

Glass-forming compositions and physicochemical properties of degradable phosphate and silver-doped phosphate glasses in the P2O5–CaO–Na2O–Ag2O system

Phosphate and silver-doped phosphate glasses are potential candidates for use as degradable biomaterials and as antibacterial materials as well. The present investigation explores the glass-forming compositions (GFC), physical properties and degradation rates of both phosphate glasses in the P2O5–CaO–Na2O ternary system and silver-phosphate glasses derived from it by introducing Ag2O in replacement of Na2O. The glasses were prepared using the traditional melting–annealing technique applied in glass making industry. Bulk glasses were prepared without using any special precautions or specific conditions (contrary to previous studies) which can prevent crystallization or segregation of silver particles from the melt. A wide glass formation domain with ≥40mol% P2O5 was determined in the ternary P2O5–CaO–Na2O system. However, up on Ag2O addition, the amount of Ag2O that can exist in the glass and remains amorphous was limited to 2mol% as ensured from X-ray diffraction (XRD). The compositions with ≥60mol% P2O5 and 0.5, 1 or 2mol% Ag2O formed transparent and colorless silver phosphate glasses. Whereas, the compositions with ≤55mol% P2O5 did not form glasses and showed immediate partial crystallization and separation of silver particles. Thereafter, the structure of representative glasses was studied by FT-IR and UV–vis absorption spectroscopy. Finally, as silver ions function as antibacterial metal ions, the amounts of silver ions released from silver phosphate glasses were measured by atomic absorption spectrometry (AAS).

A study on the effect of compositing silver oxide nanoparticles by carbon on the ‎electrochemical behavior and electronic properties of zinc‐silver oxide batteries ‎

AbstractIn this study, the effect of compositing silver oxide nanoparticles by carbon on the electrochemical behavior and electronic properties of zinc‐silver oxide batteries have been investigated. For this purpose, firstly four silver oxide electrodes containing 5, 10, 15, and 20 wt% carbon powder were produced by powder metallurgy method. For the next step, all four silver oxide electrodes were sintered at 500°C for 10 minutes. Afterward and in order to investigate the microstructure, phase and elemental analysis of the electrodes were carried out using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X‐ray Diffraction (XRD), and Energy Dispersive Spectroscopy (EDS), respectively. Moreover, in order to investigate the effect of compositing silver oxide nanoparticles by carbon on the electrochemical behavior and electronic properties of zinc‐silver oxide, electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) and electric discharge test in 1.4 wt%KOH electrolyte were carried out respectively. The microstructural observations revealed that increasing carbon content in the silver oxide electrodes results in increasing the apparent porosities in these electrodes. Investigating the phase and elemental analysis results showed that by increasing the content of carbon in the silver oxide electrode, the amount of Ag2O and AgO phases in this electrode reduces and also the extent of pure silver formation increases. Investigations on the results of electrochemical tests showed that increasing carbon content results in the reduction of corrosion resistance in silver oxide electrodes. Moreover, the results of electric discharge test revealed that the silver oxide electrode containing 10wt% carbon yields the highest energy efficiency in the zinc‐silver oxide batteries.

Fast detoxication of 2-chloro ethyl ethyl sulfide by p-type Ag2O semiconductor nanoparticle-loaded Al2O3-based supports

p-type Ag2O semiconductor nanoparticle-loaded Al2O3 or Na2SiO3/Al2O3 powders used for detoxicating the surrogate of sulfur mustard of 2-chloro ethyl ethyl sulfide (C2H5SCH2CH2Cl, 2-CEES) were investigated. Different amounts of Ag2O and Na2SiO3 on catalyst supports were evaluated. Gas chromatography with a pulsed flame photometric detector (GC–PFPD) and gas chromatography coupled with a mass spectroscopy (GC–MS) were used to monitor and identify the catalytic reactions, together with reaction products analysis. The GC analyses showed that the decontamination of 2-CEES in isopropanol solvent for 15min was above 82% efficiency for the 0.5% Na2SiO3/Al2O3 support deposited with a Ag2O content above 2.5%. 2-(ethylthio)ethanol and 2-(ethylthio)ethanoic acid were identified as the major products after catalytic reactions. The electronic holes dominating in p-type Ag2O is proposed to provide the key component and to initiate the catalytic reactions. The electronic hole-based detoxication mechanism is proposed.

Influence of silver nanoclusters on formation of PbS quantum dots in glasses

Heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag 2O, and the influence of Ag 2O on QDs was investigated. Under given heat-treatment conditions, the absorption coefficients and photoluminescence intensities of PbS QDs increased with the addition of Ag 2O. Ag clusters formed by thermal treatment nucleated formation of PbS QDs in glasses.

An improved method of ion exchange for nitrogen isotope analysis of water nitrate

Nitrate nitrogen and oxygen isotopes have been widely used to trace the nitrogen biogeochemical cycle by identifying NO 3 − sources. An improved method of anion exchange was developed to measure δ 15N-NO 3 − in fresh water by continuous-flow elemental analyzer/isotope ratio mass spectrometry (EA-IRMS). We used a custom-built exchange resin column, a peristaltic pump and the oven-drying method in our experiments. Consequently, the amount of Ag 2O used as a neutralizer was reduced, time was saved, and operation became simpler than before. Meanwhile, analytical precision remained identical to previous studies. KNO 3 solutions were prepared at 0.2, 5 and 25 mg-N L −1 from KNO 3 standard salt (δ 15N = +6.27‰), and the average δ 15N values of the solutions after having been absorbed on and subsequently stripped from anion columns were +6.62 ± 0.22‰ ( n = 6), +6.38 ± 0.09‰ ( n = 6), and +6.26 ± 0.07‰ ( n = 6), respectively. In addition, the “natural” water sample δ 15N-NO 3 − showed consistency in comparison to standards, and the mean standard deviation by the different approaches was 0.08‰. Accordingly, by these improvements the anion exchange resin technique is demonstrated to be more suitable for measuring δ 15N in NO 3 − than original techniques.

Palladium-catalysed ortho arylation of acetanilides

The palladium-catalysed direct arylation of acetanilides by using C-H activation methodology has been demonstrated. Several acetanilides were coupled with aryl iodides in the presence of 10 mol% of Pd(OAc)2, 1·0 equiv of Cu(OTf)2, and 0·6 equiv of Ag2O to afford the corresponding products in moderate to excellent yields. The results showed that the amount of Ag2O was important for this protocol.

Effect of silver oxide doping on surface and catalytic properties of Co 3O 4/Al 2O 3 system

Cobaltic oxide catalyst supported on gamma-alumina having the formula 0.1 Co 3O 4/Al 2O 3 was prepared by wet impregnation method using finely powdered Al(OH) 3 and cobalt nitrate dissolved in the least amount of distilled water. Four silver oxide-doped samples were prepared by impregnating Al(OH) 3 solid with calculated amounts of silver nitrate dissolved also in the least amount of distilled water prior to impregnation with cobalt nitrate solution. The amounts of Ag 2O were 0.2, 0.4, 0.8 and 1.6 wt.%. Pure and doped solids were subjected to heat treatment at 400, 600 and 800 °C. Diffraction lines of Co 3O 4 phase were detected in the XRD patterns of pure and doped solids precalcined at different temperatures. However, the doping process conducted at different temperatures brought about a progressive significant increase in the particle size and degree of ordering of Co 3O 4 phase. Ag 2O-doping of the investigated system affected a measurable decrease in its specific surface areas. The catalytic activities of different solids, in CO-oxidation by O 2 conducted at 125–225 °C, were found to increase significantly by increasing the amount of dopant added reaching to a maximum limit at 0.8 wt.% Ag 2O. The maximum increase in the catalytic activity expressed as reaction rate constant k measured at 150 °C over the solids precalcined at 400 °C and at 175 °C for the solids precalcined at 600 and 800 °C attained 337%, 118% and 219%, respectively. The doping process did not modify the activation energy ( E a) of the catalyzed reaction, and the observed apparent changes in E a values resulted from a compensation effect as evidenced from almost same changes in the values of pre-exponential factor of Arrhenius equation. Therefore, the observed increase in the catalytic activity of the investigated system due to Ag 2O treatment, which did not change the mechanism of the catalyzed reaction, could be attributed to an effective increase in the concentration of active sites contributing in chemisorption and catalysis of CO oxidation by O 2.

The silver/silver-oxide electrode—I. Development of electrode by slow ac cycling

The amount of Ag 2O and AgO formed and reduced within certain potential regions on a smooth silver electrode in 1 M KOH is affected by the rate of potential change through these regions. At rates of ca 2 V/min and above, the electrochemical activity associated with the formation and reduction of AgO is replaced by activity at a significantly higher electrode potential. At these rates, repeated cycles, including only partial reduction per cycle, generally yield very large amounts of over-all electrode oxidation.