Aqueous Solution Of Silver Research Articles

Формирование молекулярных кластеров серебра полимерно-солевым методом в пористых стеклах

A methodology for the formation of molecular clusters of silver in silicate nanoporous glasses has been developed. Composite materials containing molecular clusters of silver, silver nanoparticles and zinc oxide have been synthesized. The synthesis was carried out by impregnation of porous glasses in aqueous solutions of silver and zinc nitrates stabilized with high-molecular polyvinylpyrrolidone, followed by heat treatment of samples for decomposition of metal nitrates and polymer. Spectral-luminescent properties of composites have been investigated.

Formation of molecular clusters of silver by polymer-salt method in porous glasses

A methodology for the formation of molecular clusters of silver in silicate nanoporous glasses has been developed. Composite materials containing molecular clusters of silver, silver nanoparticles and zinc oxide have been synthesized. The synthesis was carried out by impregnation of porous glasses in aqueous solutions of silver and zinc nitrates stabilized with high-molecular polyvinylpyrrolidone, followed by heat treatment of samples for decomposition of metal nitrates and polymer. Spectral-luminescent properties of composites have been investigated. Keywords: porous glass, zinc oxide, silver molecular clusters, silver nanoparticles, spectral-luminescent properties.

Bioactivity of two marine algae extracts and their synthesized silver nanoparticles as safe controls against Musca domestica housefly

AbstractIn this study, two marine algae, Avrainvillea amadelpha and Codium edule, and their synthesized silver nanoparticles were evaluated against the second larval instars of the housefly Musca domestica. The marine algae‐fabricated silver nanoparticles (AgNPs) were examined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray diffraction analysis (XRD). The precolored aqueous silver solution changed from pale yellow to brown by mixing the algae extracts, revealing Ag nanocomposite production. There was a maximum UV–vis absorption at 400 nm for A. amadelpha and 420 nm for C. edule. SEM results showed that the A. amadelpha‐ and C. edule‐fabricated AgNPs were spherical and irregular in shape. A. amadelpha extract alone gave higher effective mortalities against M. domestica larvae, which were 22.1–98.3% in the tested concentrations (62.5–1,000 ppm), while a highly significant increased mortality (36.9–99.7%) was obtained from concentrations ranging from 6.3–100 ppm when A. amadelpha extract was mixed with silver nanoparticles. C. edule extract alone gave moderate effective control with 15.9–90.3% mortality using the above concentrations, whereas the mortality significantly increased (21.8–95.8%) with concentrations ranging from 6.3–100 ppm when C. edule extract was mixed with silver nanoparticles. According to the LC50 values, A. amadelpha with silver nanoparticles (LC50 9.66 ppm) provided more effective control against larval stages of M. domestica than A. amadelpha alone (LC50 133.08 ppm) by a factor of 13.776. Additionally, C. edule alone provided moderately effective control (LC50 300.37 ppm), while when mixed with silver nanoparticles, it provided highly effective control (LC50 21.34 ppm) by a factor of 14.075. Some algae extracts that synthesize silver nanoparticles offer a promising role in housefly integrated pest management (IPM) and may be an effective alternative to conventional synthetic insecticides.

Development of antimicrobial, UV blocked and photocatalytic self-cleanable cotton fibers decorated with silver nanoparticles using silver carbamate and plasma activation

In-situ preparation of silver nanoparticles (AgNPs) into plasma-pretreated cotton substrates adds novel functional properties and expands their potential applications. Herein, we report a new approach toward the assembly of multifunctional coated technical textiles. AgNPs was in-situ prepared onto plasma-pretreated cotton fibers using the simple pad-dry-cure method to impart ultraviolet protection, brilliant colors, antimicrobial and photocatalytic self-cleaning properties. AgNPs was produced by thermal reduction of excess Ag+ from an aqueous solution of silver N-(2-ethylhexyl)carbamate on the fibrous cotton surface at 130 °C. The immobilization of the generated AgNPs onto the fibers was improved by plasma activation. Both morphology and elemental content of the treated fabrics were investigated by Fourier-transform infrared spectroscopy, energy dispersive X-ray analysis and scanning electron microscopy (EDX-SEM). The morphology of the generated AgNPs was also investigated by means of transmission electron microscopy (TEM). The generated AgNPs exhibited a homogeneous distribution and high depositing density with a nanoparticle size between 35 and 80 nm. AgNPs incorporated onto cotton fibers endowed with brownish-yellow color for plasma-untreated fibers and brown for plasma-pretreated fibers. The colorfastness and color strength of the AgNPs-coated fabrics were explored. The colored cotton fibers demonstrated persistent antimicrobial performance to S. aureus, E. coli and C. albicans pathogens. AgNPs/cotton displayed excellent photocatalysis and self-cleaning properties to the photochemical decomposition of methylene blue.

Biosynthesis of silver nanoparticle using flowers of Calotropis gigantea (L.) W.T. Aiton and activity against pathogenic bacteria

Silver nanoparticles (AgNPs) from silver nitrate solution are carried out using the flower extract of Calotropis gigantea. Silver nanoparticles were characterized by UV–vis spectrophotometer, X-Ray diffractometer (XRD). Reduction of silver ions in the aqueous solution of silver during the reaction was observed by UV–vis spectroscopy. Crystalline nature of synthesized silver nanoparticles was studied by XRD pattern, refraction peak using the Scherrer’s equation. Antibacterial activity of the silver nanoparticles was performed by disc diffusion method against Bacillus subtilis, Pseudomonas putida and Escherichia coli. The antibacterial activity of synthesized silver nanoparticles by flower extract of C. gigantea was found against B. subtilis (10 mm). Synthesised AgNPs has the efficient antibacterial activity against Gram positive bacteria.

Two-beam laser fabrication technique and the application for fabricating conductive silver nanowire on flexible substrate

In this study, a two-beam laser fabrication technique is proposed to fabricate silver nanowire (AgNW) on the polyethylene terephthalate (PET) substrate. The femtosecond pulse laser in the technique plays a role in generating Ag nanoparticles from the silver aqueous solution by multiphoton photoreduction. The continuous wave (CW) laser of the technique works as optical tweezers, and make the Ag nanoparticles gather to a continuous AgNW by the optical trapping force. The optical trapping force of the CW laser was calculated under our experimental condition. The flexibility and the resistance stability of the AgNW that fabricated by this technique are very excellent. Compared to the resistance of the AgNW without bending, the decreasing rate of the AgNW resistance is about 16% under compressed bending condition at the radius of 1 mm, and the increasing rate of the AgNW resistance is only 1.3% after the AgNW bended about 3500 times at the bending radius of 1 mm. The study indicates that the AgNW is promising for achieving flexible device and would promote the development of the flexible electronics.

Silver deposition on stainless steel container surfaces in contact with disinfectant silver aqueous solutions

Silver is the preservative used on the Russian segment of the International Space Station (ISS) to prevent microbial proliferation within potable water supplies. Yet, in the frame of the European Automated Transfer Vehicle (ATV) missions to ISS, silver depletion from water has been detected during ground transportation of this water to launch site, thereby indicating a degradation of water quality. This study investigates the silver loss from water when in contact with stainless steel surfaces. Experiments are conducted with several types of stainless steel surfaces being exposed to water containing 10 or 0.5mg/L silver ions. Results show that silver deposits on stainless steel surfaces even when a passivation layer protects the metallic surface. The highest protection to silver deposition is offered by acid passivated and electropolished SS 316L. SEM and XPS experiments were carried out at several locations of the sample area that was in contact with the Ag solution and found similar morphological (SEM) and compositional (sputter-etch XPS) results. The results reveal that silver deposits uniformly across the wetted surface to a thickness larger than 3nm. Moreover, evidence is provided that silver deposits in its metallic form on all stainless steel surfaces, in line with a galvanic deposition mechanism. Combination of ICP-MS and XPS results suggests a mechanism for Ag deposition/reduction with simultaneous substrate oxidation resulting in oxide growth at the exposed stainless steel surface.

INSECTICIDAL ACTIVITY OF BIO-SILVER AND GOLD NANOPARTICLES AGAINST PERICALLIA RICINI FAB.(LEPIDAPTERA: ARCHIDAE)

A laboratory experiment was conducted to evaluate the impact of silver aqueous solution, gold aqueous solution, pungamoil, pungamoil-based silver nanoparticles (PO-AgNPs) and pungamoil-based gold nanoparticles (PO-AuNPs), vijayneem against Pericallia ricini larval mortality, development and fecundity and gravimetric analyses. The results showed that Ag+ aqueous solution as well as pungamoil-based gold nanoparticles caused more mortality than commercial neem insecticide (vijayneem). Aqueous solutions of Ag+ and Au+ drastically reduced the body weight of P. ricini larvae. PO-AgNPs and POAuNPs treatment drastically enhanced the food consumption, assimilation but reduced the conversion, subsequently affecting growth. Distinct difference was noticed between PO-AgNPs and PO-AuNPs treatments in larval, pupal and adult developmental periods, fecundity and hatchability. It is recommended to integrate PO-AgNPs and PO-AuNPs in pest management; however, field evaluations and bio-safety assessments were imperative before the utilization of these bio-nanoparticles were recommended.

Tailored silver grid as transparent electrodes directly written by femtosecond laser

We present the design and realization of silver grid transparent electrodes (SGTEs) easily fabricated by femtosecond laser direct writing of silver aqueous solution. The fabricated SGTEs with a sheet resistance down to 47 Ω/□ and optical transmittance up to 93% are demonstrated. These sheet resistance and transmittance values are comparable to commercially available indium tin oxide. High uniform morphology of the directly written SGTEs results in the ultra-stable tailored performance parameter at electronic and optical fields. The sheet resistance and transmittance can be tailored precisely by manipulating the filling fraction of the uniform SGTEs. This study provides an approach for creating SGTEs in a controllable fashion, and the SGTEs exhibit high transmittance and low sheet resistance, which could open up new avenues towards widespread application in electronics, photovoltaics, and optoelectronics.

Antibacterial and Antimycotic Activity of Cotton Fabrics, Impregnated with Silver and Binary Silver/Copper Nanoparticles.

Effective method of obtaining of the bactericidal bandage materials by impregnation of cotton fabric by aqueous solutions of silver and copper salts followed by a certain regime of heat treatment is developed. The study of obtained materials by methods of optical spectroscopy, electron microscopy, and X-ray phase analysis showed the formation of crystalline silver nanoparticles (NPs) and bimetallic Ag/Cu composites with the corresponding surface plasmon resonance (SPR) bands in the absorption spectra. High antimicrobial and antimycotic properties of tissues with low concentrations of Ag and Ag/Cu nanoparticles (Ag/Cu NPs) (in the range 0.06–0.25 weight percent (wt%) for Ag and 0.015–0.13 wt% for Ag/Cu) is confirmed in experiments with a wide range of multidrug-resistant bacteria and fungi: Escherichia coli, Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, Candida albicans yeasts, and micromycetes. Textile materials with Ag NPs demonstrate high antibacterial activity, while fabrics doped with bimetallic composite Ag/Cu have pronounced antimycotic properties. Bactericidal and antifungal properties of the obtained materials do not change after a washing. Production of such materials is extremely fast, convenient, and cost-effective.

Study of photochromic silver-containing quartz-like glass using X-ray diffraction methods

Photochromic quartz-like glassess obtained by sintering plates of porous glass, which were successively impregnated with an aqueous solution of silver nitrates with or without the presence of sensitizers (copper or cerium nitrates) and halides (NH4Cl, KBr, KI) are studied using the methods of X-ray difraction and small-angle X-ray scattering (SAXS). It is shown that the main crystalline phases in the composition of lightsensitive regions formed in quartz-like glass are AgBr and KBr in the form of nanodimensional crystals with a size of 100–130 A. The sizes of the scattering regions according to the data of small-angle scattering are amount to 250–300 A. The temperatures of melting and crystallization of light-sensitive phases are determined from the temperature dependences of the SAXS intensity.

Obtaining the nanosized particles from aqueous solution of silver by plasma chemical method

В данной работе исследовалось влияние процесса плазмохимической обработки водных растворов, содержащих ионы серебра, на образование наноразмерных частиц серебра, их размеры и характер их изменения в заданном временном промежутке. Полученные результаты планируется использовать для создания уточненной математической модели процесса плазмохимической обработки жидких сред.

Vermiculite With Ag and Cu Used as an Antibacterial Nanofiller in Polyethylene/ Vermikulit S Ag A Cu Použitý Jako Antibakteriální Nanoplnivo V Polyethylenu

Abstract Vermiculite (Ver) enriched with silver and copper was used as nanofiller to the polyethylene (PE) matrix. Specifically, the low density polyethylene (LDPE) was chosen as a matrix. The samples Ver-Ag,Cu were prepared by shaking of Ver with the aqueous solutions of silver and copper nitrate. The mixtures of the Ver nanofillers and PE were homogenized by melt compounding technique and further thin plates were pressed from stiff matter of PE with Ver nanofiller. The exfoliation of the powdery Ver nanofillers in PE matrix was characterized by the X-ray diffraction analysis of thin plates. Distribution of Ver nanofiller in PE matrix was observed by Light microscopy. The reinforcing effect of nanofillers onto PE matrix was studied by creep experiment. Antibacterial activity of powder Ver-Ag,Cu samples and surfaces of PE/Ver-Ag,Cu samples was tested on the Gram-positive bacteria Enterococcus faecalis. All tested PE/Ver-Ag,Cu surfaces showed good antibacterial behaviour after 24 h in comparison to pure PE. The number of colonies decreased from the countless number to several hundred colonies.

Fluorescence emission spectra of silver and silver/cobalt nanoparticles

Various aqueous solutions of silver and silver/cobalt nanoparticles (Ag and Ag/Co NPs) were obtained, and their fluorescence emission spectra have been studied. First, colloidal Ag NPs were prepared by an electrochemical method under different time intervals and at different rotation speeds of rotating electrode. Next, in a reduction method, Ag/Co core–shell NPs were prepared, using Ag NPs as a core. The core–shell structure of Ag/Co NPs has been demonstrated by the Transmission Electron Micrograph (TEM) and X-Ray Diffraction (XRD) pattern. The fluorescence emission spectra of Ag and Ag/Co NPs, at different ranges of excitation wavelength, were investigated, which revealed two kinds of fluorescence emission peak. The shorter emission peak was fixed at about 485 (for Ag NPs) and 538 nm (for Ag/Co NPs). For both NPs, with an increase in excitation wavelength, the latter emission peak becomes red-shifted. The effect of duration time and rotation speed of the rotating electrode, in the electrochemical preparation of Ag NPs, on its fluorescence emission spectra, has also been investigated.

Ag2O3 clathrate is a novel and effective antimicrobial agent

Silver compounds and silver ions are used extensively in medical devices because of their wide-spectrum antimicrobial activity. In particular, nanoparticles of silver and silver (I) oxide show great promise for widespread usage in medical polymers and nanodrugs. Here, we demonstrate that a crystalline powder and a saturated aqueous solution of silver (III) oxide clathrate show much stronger antimicrobial activities and oxidative activities than silver (I) oxide.

Biogenic Synthesis Of Silver Nanocubes And Nanorods Using Sundried Stevia Rebaudiana Leaves

This work reports a novel biological method for the synthesis of rod shaped silver nanoparticles by exploiting sundried Stevia rebaudiana leaves at ambient conditions. On treatment of aqueous solutions of silver with leaf powder, not only the rod shaped silver nanoparticles ranging from 80-200 nm diameter and 400-800 nm height, but also cubes ranging from 55 to 80 nm in size, could be rapidly fabricated. The rate of reduction is much faster than those observed in earlier studies, highlighting the possibility that biological methodologies will achieve rates of synthesis comparable to those of chemical methods. The approach also appears to be a cost-efficient alternative to conventional methods, so it would be suitable for developing a biological process for large scale production. Instead of the boiled leaf broth used in previous studies, sundried leaf biomass could be preserved as an excellent bio-reductant, conveniently available any time for biosynthesis of the nanoparticles. Copyright © 2010 VBRI press.

Crystallization of silver through reduction process using Elaeis guineensis biosolid extract

This study presents a special, economically valuable, unprecedented eco-friendly green process for the synthesis of silver nanoparticles. The silver nanoparticles were obtained from a waste material with oil palm biosolid extract as the reducing agent. The use of the oil palm biosolid extract for the nanoparticle synthesis offers the benefit of amenability for large-scale production. An aqueous solution of silver (Ag(+) ) ions was treated with the oil palm biosolid extract for the formation of Ag nanoparticles. The nanometallic dispersion was characterized by surface plasmon absorbance measuring 428 nm. Transmission electron microscopy showed the formation of silver nanoparticles in the range of 5-50 nm. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction analysis of the freeze-dried powder confirmed the formation of metallic silver nanoparticles. Moreover, Fourier Transform Infrared Spectroscopy provided evidence of phenolics or proteins as the biomolecules that were likely responsible for the reduction and capping agent, which helps to increase the stability of the synthesized silver nanoparticles. In addition, we have optimized the production with various parameters.

Metal−Metal Bonding and Structures of Metal String Complexes Cr3(dpa)4Cl2, Cr3(dpa)4(NCS)2, and [Cr3(dpa)4Cl2](PF6) from IR, Raman, and Surface-Enhanced Raman Spectra

We recorded infrared, Raman, and surface-enhanced Raman scattering (SERS) spectra of metal-string complexes Cr(3)(dpa)(4)X(2) (dpa = di(2-pyridyl)amido, X = Cl, NCS) and [Cr(3)(dpa)(4)Cl(2)](PF(6)) and dipyridylamine (Hdpa) to determine their vibrational frequencies and to study their structures. For the SERS measurements these complexes were adsorbed on silver nanoparticles in aqueous solution to eliminate the constraints of a crystal lattice. From the results of analysis of the vibrational normal modes we assign the infrared band at 346 cm(-1) to the Cr(3) asymmetric stretching vibration of the symmetric form and the Raman line at 570 cm(-1) to the Cr-Cr stretching mode for the unsymmetric form of Cr(3)(dpa)(4)Cl(2). Complex Cr(3)(dpa)(4)Cl(2) exhibits both symmetric (s-) and unsymmetric (u-) forms in solution but Cr(3)(dpa)(4)(NCS)(2) only the s-form. The structures for both complexes in their ground states have the s-form. The oxidized complex [Cr(3)(dpa)(4)Cl(2)](PF(6)) has only a u-form for which the Cr-Cr stretching mode is assigned to the band at 570 cm(-1). From the variation with temperature from 23 to 60 degrees C of the intensity of this line, we obtained the proportion of the u-form Cr(3)(dpa)(4)Cl(2); the enthalpy change is thus obtained to be DeltaH = 46.2 +/- 3.3 kJ mol(-1) and the entropy change is DeltaS = 138 +/- 10.3 J K(-1) mol(-1) for the reaction u-Cr(3)(dpa)(4)Cl(2) <--> s-Cr(3)(dpa)(4)Cl(2). From the spectral intensities and band frequencies in SERS spectra, Hdpa is expected to adsorb on a silver nanoparticle with the amido nitrogen and pyridyl rings tilted from the silver surface, whereas the trichromium complex with the chromium ion line is orthogonal to the silver surface normal in aqueous silver solution.

Effect of gas environment on properties of particles prepared by spray pyrolysis of metal nitrates

Particles in different states of oxidation were prepared by spray pyrolyses of aqueous solutions of silver and copper nitrates under different gas environments: air, nitrogen or mixture gas of 10 vol%H2-N2, respectively. Silver nitrate was converted to phase-pure silver at temperatures below 500 o C whose densification and crystallization were completed around 500

Highly Reflective and Conductive Double-Surface-Silvered Polyimide Films Prepared from Silver Fluoride and BTDA/4,4‘-ODA

This work focuses on surface silver metallization on a 3,3',4,4'-benzophenonetetracarboxylic dianhydride/4,4'-oxydianiline (BTDA/ODA)-based polyimide matrix via a direct ion-exchange self-metallization technique using a simple silver salt, silver fluoride, as the silver precursor. The method involves performing an ion-exchange reaction of damp-dry poly(amic acid) films in silver aqueous solution to form silver(I)-containing precursor films. Thermal treatment under tension converts the poly(amic acid) into polyimide and simultaneously reduces the silver(I) to silver(0), yielding silver layers with excellent reflectivity and conductivity on both film sides. However, significant property differences were exhibited on the upside and underside surfaces of the metallized films and this has been discussed in detail. The variation of surface properties and surface morphologies during the thermal curing cycle was also investigated. The mechanical and thermal properties of the metallized polyimide films are essentially similar to those of the host polyimide.