Different Amounts Of Silver Research Articles

Preparation and characterization silver/zirconium nickel oxide nanocomposites with negative electromagnetic parameters

Different amounts of silver (0–45wt%) have been synthesized with Zr0.9Ni0.1Oy based on co-precipitation technique. Doping with silver metal is an interesting way to achieve the double negative (DNG) properties. The morphology and structure properties of Ag/Zr0.9Ni0.1Oy nanocomposite were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The XRD analysis showed that no reaction took place between Zr0.9Ni0.1Oy and silver during calcination and sintering. SEM observation showed that the silver particles presented homogenous particle distribution in the Zr0.9Ni0.1Oy matrix. The electrical and magnetic properties of the silver-doped Zr0.9Ni0.1Oy were investigated. It was found that silver doping results in both negative permittivity and negative permeability possibly due to the incorporation of Ag atoms in the percolation network. Our results suggest that the Ag/Zr0.9Ni0.1Oy is a suitable candidate for DNG materials.

Absorption and photoluminescence properties of silver clusters in SiO2 matrix

Absorption and luminescence properties of silver nanoclusters embedded in SiO2 matrixes were studied experimentally. Thin SiO2 films with different amount of silver were produced by co-deposition of Ag and SiO2 onto the silica substrates in vacuum. The thus obtained films possess three peaks in absorption spectra at 297, 329 and 401 nm and two peaks in luminescence spectra at about 500 and 650 nm. We ascribed these spectral features to silver nanoclusters of different sizes that present in the film. Thermal annealing transforms both absorption and emission spectra of the films. Lager clusters that are formed after annealing possess one absorption band at 350–450 nm and one luminescence band at 510 nm. The luminescence was observed only in samples with the silver content of less than 2.2%. Quenching of the luminescence in samples with higher concentration of silver is due to the presence of larger particles with plasmonic properties.

The removal of mercury (II) from water by Ag supported on nanomesoporous silica.

In this study, the synthesis of SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10%) has been investigated under acidic conditions by using P123 as a template via the direct method. The nanocomposites of SBA-15 were synthesized by the same method andby the addition of silver salt. Finally, the nanocomposite materials were examined for the removal of mercury ions from wastewater as an adsorbent by the reverse titration method. Characterization was carried out through x-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption-desorption (Brunauer-Emmett-Teller). XRD spectra confirmed the presence of silver nanoparticles within the amorphous silica matrix of SBA-15. The Barrett-Joyner-Halenda analysis showed that SBA-15 and SBA-15/Ag have a narrow pore size distribution. SEM images demonstrated that the morphology of the matrix of SBA-15 is in spherical state. Furthermore, wavelength dispersive x-ray spectroscopy identified the presence and distribution of silver nanoparticles inside the pore channels and outside of them. Typical TEM images of SBA-15 and SBA-15/Ag (5wt.%) indicated a regular hexagonal pore structure with long-range order and long channels. In SBA-15/Ag (5wt.%) sample, the nanoparticles of silver was found into the pores and outside of them. The removal of mercury ions from wastewater using mesoporous silica nanocomposite containing silver nanoparticles was studied by the reverse titration analysis. The best capacity of adsorption of mercury ions from wastewater was obtained for SBA-15/Ag (5wt.%) sample, which was equal to 42.26mg/g in 20min at pH of 7. The Freundlich model was used to explain the adsorption characteristics for the heterogeneous surface, and [Formula: see text] (adsorption capacity) and n (adsorption intensity) were determined for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10%). The value of R2 was about 0.99, 0.99, 0.98, and 0.98 and Kf was about 42, 48, 58, and 58mg/g for SBA-15/Ag, SBA-15/Ag (2.5%), SBA-15/Ag (5%), and SBA-15/Ag (10%), respectively. Furthermore, the values of n >1 show a favorable adsorption process for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials. Moreover, the Langmuir isotherm model evaluation showed that the correlation coefficients for all concentrations were R2 >0.99, indicating that Hg (II) ions were adsorbed on the surface of SBA-15/Ag via chemical and physical interaction. Additionally, the analytic hierarchy process (AHP) and Technique of Order Preference Similarity to the Ideal Solution (TOPSIS) methods that depend on the criteria of the surface area, amount of adsorbent, pore volume, and cost of synthesis were used. The evaluation of results showed that the best sample was SBA-15/Ag (5wt.%). Furthermore, the research work highlighted the antibacterial nanocomposite with suitable adsorption of Hg (II) ions from water solutions and supported its potential for environmental applications. This nanocomposite can be used in the absorption domain of Hg (II) ions from water solutions.

Optical modifications at the intrinsic absorption threshold in soda lime silicate glass by Ag+–Na+ ion exchange

Silicate glass slides with different alkali metal and alkaline earth metal content were doped with different amounts of silver by Ag+–Na+ ion exchange in order to obtain glass showing strong luminescence in the visible spectral range suitable for solar glass or UV-LED-lenses. After excitation at λ=325nm (Eex=3.815eV) an enhancement of more than two orders of magnitude for broad white emission centered at about Eem≈2.3eV is achieved. Modifications of doped glass are investigated by absorption spectrophotometry for monitoring the intrinsic absorption threshold and by polarized photoluminescence spectroscopy for evaluating the enhanced emissions. The luminescence enhancement requires a modification of the intrinsic absorption threshold due to a decreased optical band gap. This is explained by a locally driven redox-reaction, which also should form at least one reduced silver containing species. The formed bright intra-ionic luminescence center creates a structure with at least three energy levels. This center is assumed to be closely related with the band structure and should cause a creation of holes, electrons or one of their bound states like excitons or polarons.

Preparation of vanadium oxide thin films modified with Ag using a hybrid deposition configuration

The application of a hybrid deposition configuration, formed by the interaction of a laser ablation plasma with a flux of atomic vapor, to deposit vanadium oxide thin films modified with different amounts of silver, is reported. The effect of the amount of Ag incorporated in the films on their structural, morphological, compositional and optical properties was studied. The obtained results reveal that films with variable Ag content from 11.7 to 24.6 at.% were obtained. Depending on the silver content, the samples show very different surface morphologies. Optical characterization indicates the presence of nanostructures of Ag. Thin films containing silver exhibit better photocatalytic performances than unmodified V2O5 films. Raman spectra reveal that as the silver content is increased, the signals associated with V2O5 disappear and new modes attributed mainly to silver vanadates appear suggesting the formation of ternary compounds.

Loading effects of silver nanoparticles on hydrogen photoproduction using a Cu-TiO2 photocatalyst

In this study, Cu-TiO2 photocatalysts were synthetized by means of a sol-gel procedure using a copper diglycinate complex as precursor. Surface functionalization with silver nanoparticles was carried out by a UV photoreduction method. Several techniques such as XRD, DRS, TEM and N2 physisorption were used to characterize the structural, morphological and surface properties of the photocatalysts. Hydrogen photoproduction tests were performed in an isopropyl alcohol-water solution and without using any other redox mediator. Different amounts of silver and copper on TiO2 were examined to better understand their function in the photocatalytic production of hydrogen. The obtained photoproduction rates of pristine TiO2, Cu1TiO2 and Ag3/Cu1TiO2 were 631, 3365 and 3920μmolg−1h−1, respectively.

Microbial growth inhibition caused by Zn/Ag-Y zeolite materials with different amounts of silver

Different loadings of silver exchanged on bimetallic Zn/Ag-NaY zeolite materials were studied for antimicrobial properties against four reference microorganisms. The sensitive indicator strains used were two bacteria (Escherichia coli and Bacillus subtilis) and two yeast species (Saccharomyces cerevisiae and Candida albicans). The bimetallic materials were compared with the monometallic materials prepared with the same concentrations of silver. A synergistic effect between the two metals, zinc and silver, was evidenced on the antimicrobial activity of the materials. All mono and bimetallic materials showed strong efficacy against bacteria and yeasts, although the later overall displayed lower MIC values. The results of X-ray photoelectron spectroscopy (XPS) confirm the presence of silver and zinc as ions, not homogeneously distributed throughout the zeolite framework, which implies that the metal ions are located in different sites of the faujasite structure.

Control of Bioaerosols in Indoor Environment by Filter Coated with Nanosilicate Platelet Supported Silver Nanohybrid (AgNPs/NSP)

ABSTRACTCurrently silver nanoparticles (AgNP)-modified filter are widely used to inactivate airborne microbes in indoor environment. However, AgNP is extremely small and thus will penetrate cells membranes to cause cytotoxicity. AgNPs/NSP has been proven to be less cytotoxic to human body. In this study, it was the first time that AgNPs/NSP was used to develop a new antimicrobial air filter with low cytotoxicity. The AgNPs/NSP filter was made by dip-coating of filter with AgNPs/NSP and acrylic resin solution and three different amount of silver on filter were obtained including 12.6, 31.5 and 63 ppm. The filtration efficiency and the antimicrobial activity of AgNP/NSP filter were evaluated by bioaerosols including Escherichia coli and Candida famata in testing chamber and HVAC simulation system under 30% and 70% relative humidity (RH). The results showed that filtration efficiency of AgNPs/NSP-modified filter increased by about 13 to 20% compared to unmodified filter for E. coli but remained almost the same for C. famata. The antimicrobial efficiency of AgNPs/NSP modified filter of 63 ppm was 95.1% for E. coli at RH of 30%. In addition, 91% of antimicrobial efficiency for C. famata was found at RH of 70%. On the other hand, the antimicrobial efficiency of yeast for AgNPs/NSP-modified filter was 97.8% and 86.4% for RH of 30% and 70% respectively when yeast just started to contact with filter in HVAC system. The results suggest that AgNP/NSP-modified air filter can effectively inactivate microorganisms retained on. Therefore, emission of bioaerosols from air filter can be avoided in order to improve the air cleaning technology in indoor environment.

P106] Spinodal decomposition of Ag-Cu nanoparticles

In this study, Cu-TiO2 photocatalysts were synthetized by means of a sol-gel procedure using a copper diglycinate complex as precursor. Surface functionalization with silver nanoparticles was carried out by a UV photoreduction method. Several techniques such as XRD, DRS, TEM and N2 physisorption were used to characterize the structural, morphological and surface properties of the photocatalysts. Hydrogen photoproduction tests were performed in an isopropyl alcohol-water solution and without using any other redox mediator. Different amounts of silver and copper on TiO2 were examined to better understand their function in the photocatalytic production of hydrogen. The obtained photoproduction rates of pristine TiO2, Cu1TiO2 and Ag3/Cu1TiO2 were 631, 3365 and 3920 μmol g−1 h−1, respectively.

Electromagnetic shielding response of UV-induced polypyrrole/silver coated wool

In this research, wool surface was successfully coated with polypyrrole (PPy) by one-step UV-induced polymerization using AgNO3 as catalyst for oxidation of pyrrole monomers. The influence of the concentration of materials on the surface morphology, thermal and electromagnetic shielding properties was investigated using FTIR, XRD, SEM, EDS, TGA, RS and NA. The new bands at 2369 and 1519 cm-1 appeared in FTIR clearly showed structural changes of wool proteins. XRD spectra revealed two new peaks related to silver planes at 2θ=33° and 47° for UV-induced PPy/Ag nanocomposite coated wool. Furthermore, EDS results confirmed the presence of different amounts of silver on wool proportional to the applied PPy/Ag nanocomposites. TGA results demonstrated that the PPy/Ag nanocomposite coatings could significantly improve the thermal stability of wool fibers. This paper introduces a simple and versatile method for production of PPy/Ag nanocomposite, which can be applied as a high electromagnetic shielding on textiles.

Increasing the effective work function of multilayer graphene films using silver nanoparticles

The authors report a practical method to increase the effective work functions of multilayer graphene (MLG) films for high work function transparent electrodes. MLG films were prepared using a chemical vapor deposition and transfer process. The effective work functions of MLG films covered with different amounts of silver (Ag) nanoparticles were measured using ultraviolet photoelectron spectroscopy (UPS). The formation of Ag nanoparticles on the MLG surface was investigated using scanning electron microcopy. The sheet resistance and transmittance of the MLG films were also measured with different amounts of Ag nanoparticles on the MLG surfaces. The UPS measurements revealed that the effective work function of an MLG film could be increased from 4.39 to 4.55 eV by adding Ag nanoparticles onto the MLG surface with minimal changes in the sheet resistance and transmittance.

Application of Ag-Doped Nano-TiO<sub>2</sub> Prepared at Low-Temperature to Multi-Functional Finishing of Cotton Fabric

Ag-doped nano-TiO2 sol was prepared at a low temperature and was used to finishing cotton fabrics, and observed the crystal structure and the dispersion of nano-TiO2 on the fabric by X-ray diffraction (XRD) and scanning electron microscope (SEM); Discussed the influence of different amount of silver on antibacterial properties; Studied the impact of different finishing methods on UV resistance performance as well as the degradation of methylene blue and VOC performance. Results showed that Ag-doped nano-TiO2 on the fabric which was finished by steaming method with the sol agent were anatase phase,and its particle size was 20-40 nm, when the molar ratio of tetrabutyl titanate and silver nitrate was 70:1, the Bacteriostatic rate was 99.9%, and fastness to washing was well, UV resistance and degradation of MB and VOC performance had greatly ascended, and less influence on the fabric performance.

Silver Ions Release from Antibacterial Chitosan Films Containing in Situ Generated Silver Nanoparticles

This study aims to develop antimicrobial films consisting of chitosan and silver nanoparticles that are homogeneously distributed throughout the polymer matrix. Nanoparticles were generated in situ during the neutralization of the chitosan acetate film with sodium hydroxide. The temperature of neutralization and the concentration of silver in the film were crucial determinants of the shape and size of the nanoparticles. Neutralized films exhibited antimicrobial activity against Escherichia coli and Staphylococcus aureus in liquid growth media. However, the effectiveness of the films was considerably greater in diluted growth media. Furthermore, no significant differences were found either in the antimicrobial capacities of films incorporating different amounts of silver or in the amount of silver that migrated into the liquid media after 18 h of immersion of the film. Neutralized films maintained their activity after 1 month of immersion in deionized water, which can be attributed to the slow sustained release of silver ions and thus efficacy over time.

Effect of silver addition on the microstructures and electrical responses of La(1.7)Sr(0.3)Mo(2)O(9 − δ) ceramics

Different amounts of silver (3–15wt.% Ag2O) have been mixed with ceramic powders based on La1.7Sr0.3Mo2O9−δ (LSM). XRD analysis indicated that the silver was chemically stable in LSM. TEM observation and XPS analysis showed that some metallic silver atoms presented random distribution in the LSM ceramic, while others entered into crystal lattice in the form of Ag+, efficiently stabilizing the cubic phase at the room temperature. And there were a great enhancement on conductivity in Ag added (<10wt.% Ag2O) LSM ceramics. Also addition of Ag had a significant influence on the surface oxygen exchange properties with electrode components.

Photocatalytic performances and activities of ZnAl2O4 nanorods loaded with Ag towards toluene

In this study, photocatalysts of ZnAl2O4 nanorods were obtained by adjusting pH values of the solution through hydrothermal routes, and then the Ag/ZnAl2O4 catalysts under pH=6 were synthesized via loading different amounts of silver. Their structural properties were systematically investigated by SEM, TEM, XRD, BET, DRS, XPS and FTIR techniques. The photocatalytic performances and activities of the prepared samples and commercial P25 were comparatively studied by the degradation of gaseous toluene under UV irradiation in in situ FT-IR reactor. The results revealed that the prepared Ag/ZnAl2O4 nanorods with loading 1wt.% Ag were more active than other prepared samples and commercial P25 in photocatalytic oxidation of gaseous toluene. Hydroxyl groups on the surface of Ag/ZnAl2O4 nanorods are able to react with photo-produced benzaldehyde, which is then retained on the catalyst surface leading to the progressive deactivation of the catalyst in the gas–solid system. The photocatalytic oxidation of gaseous pollutant over UV-illuminated Ag/ZnAl2O4 nanorods is a promising technique for air purification.

Studies on Properties of AgAl2O3 Nanocomposite Synthesized by Solution Combustion Technique Under Novel Condition

Ag\Al2O3 nanocomposite were synthesized by solution combustion Technique using ammonium carbonate as a new fuel under simultaneous combustion of alumina and silver particles condition. Samples prepared with different amount of silver, were characterized by XRD, BET, SEM and optical Absorption measurements. XRD analysis was used to determine the change in phase and size of the synthesized nanoparticle with adding silver. BET analysis showed that added silver reduced specific surface but which is still suitable for catalytic application. BJH analysis showed that pores in Ag/Al2O3 nano composite are mesoporous and in Al2O3 nano particles is microporous. TEM and SEM showed that silver was distributed completely homogenously in pores of Alumina, and didn’t change in surface of Alumina. Optical transmission showed the different existence of different Ag species.

Performance of Ag-TiO2Photocatalysts towards the Photocatalytic Disinfection of Water under Interior-Lighting and Solar-Simulated Light Irradiations

This paper reports the characterization and photoactivity of Ag-TiO2materials using different amounts of silver during the hydrothermal synthesis. Photocatalysts were characterized by means of TEM, XPS, XRD, DRS, and N2sorption isotherms to determine the textural properties. The photocatalyst's configuration was observed to be as anatase-brookite mixed phase particles with Ag partially oxidized aggregates on the TiO2surface, which increased visible light absorption of the material. Moreover, photoproduction of singlet oxygen was followed by EPR analysis under visible light irradiations following the formation of TEMPOL. Such photoproduction was totally decreased by using the singlet oxygen scavenger DABCO. Photocatalysts were tested towards the photocatalytic disinfection of water suing a solar light simulator and an interior-light irradiation setup. Results evidenced an increase in the photooxidative effect of TiO2, while dark processes evidenced that part of the inactivation process is due to the Ag-TiO2surface bactericidal effect and possible lixiviated Ag+.

FTIR studies of butane, toluene and nitric oxide adsorption on Ag exchanged NaMordenite

In this work, we studied the adsorption of butane, toluene and nitric oxide on NaMordenite exchanged with different amounts of silver. The reactions that occurred when the adsorbed hydrocarbons interacted with NO and the effect of water adsorption were also addressed. Different silver species were formed after ion exchange and they were detected by TPR analysis. Highly dispersed Ag2O particles were reduced at temperatures lower than 300 °C whereas Ag+ exchanged ions showed two TPR peaks, which can be ascribed to species exchanged at different mordenite sites. The TPD experiments after adsorption of NO at 25 °C showed that the only desorbed species was NO2 which was formed by the total reduction of Ag2O particles. When the adsorbed butane was exposed to NO (1000 ppm), isocyanate species were formed on Ag+ ionic sites as well as Ag+–(NOx)–CO species. Toluene adsorption was stronger than butane since adsorbed toluene molecules were held even at 400 °C. The characteristic bands of the aromatic ring C=C bond was observed as well as that of methyl groups interacting with Ag+ and Na+ ions. However, the appearance of carboxylic groups at temperatures above 300 °C in inert flow indicated the partial oxidation of toluene due to Ag2O species present in the samples. After contacting adsorbed toluene with NO, different FTIR bands correspond to organic nitro-compounds, isocyanate, cyanide and isocyanide species adsorbed on Ag+ ions, were detected. The presence of water inhibited the formation of NO2 species and the hydrocarbon adsorption on Na+ sites but did not affect the toluene-Ag+ interaction.

Improvement of surface properties of titanium-based implants with micro-arc method

E-mail address: muhaffel@itu.edu.tr (F. Muhaffel) Titanium and its alloys have high mechanical properties, superior corrosion resistance, bone-like elasticity module, low density and high bio-compatibility. These properties make them preferable in medical applications due to their wide application fields. Titanium oxide layer that occurs on the surface is bio-compatible however the most important issue of bio-inert materials to improve bone–tissue binding after implantation. This situation is affecting the success of implantation. In order to provide the bio-active surface in medical titanium alloys, it is determinedly studied to form a hydroxyapatite layer on a titanium oxide layer. To ensure the formation of hydroxyapatite, micro-arc oxidation method is used by many researchers nowadays. In this study, the aim is to develop a microporous, rough and antibacterial surface on Ti6Al4V alloy via micro-arc oxidation process. Different amount of silver added to micro-arc oxidation solution and examined the antibacterial effect of silver concentration.

Dry sliding wear behavior of silver containing Ni-based composite-steel tribo-pair

Ni-based self lubricating composites containing four different amounts of silver were prepared by powder metallurgy (PM) route. The room temperature friction and wear behavior was investigated by carrying out dry sliding experiments against bearing steel using a ring-on-disk configuration. Tests were conducted at a constant load of 100N and different sliding speeds of 0.5, 1.0 and 1.5 m/s to analyze the effect of both the speed and the silver content on the wear behavior of the tribo-pair. The friction coefficient and the wear rate of the composites were found to decrease with increasing both the sliding speed and the silver content. The wear rate of the counterface was observed to be a little higher when it was siding against the composite having silver in comparison to that without any silver. However, the overall wear rate of the tribo-pair was found to decrease with increasing sliding speed and silver content.