Amount Of Silver Nitrate Research Articles

Investigation of Electrical, Thermal and Structural Properties on Polyacrylonitrile Nano-Fiber

Polymer composite nano-fibers including (1, 3 wt %) silver nano-particles have been produced by electrospinning method. Polyacrylonitrile/N,N-dimethylformamide (PAN/DMF) solution have been prepared and the amount of silver nitrate have been adjusted to PAN weight. Silver nano-particles were obtained from reduction of silver ions into silver nano-particles by chemical reduction by hydrazine hydroxide (N2H5OH). The different amount of silver salt was loaded into polymer matrix to obtain polyacrylonitrile composite nano-fiber containing silver nano-particles. The effect of the amount of silver nano-particles on the properties of composite nano-fiber web was investigated. Electrical conductivity, mechanical properties, thermal properties were examined by Microtest LCR Meter 6370 (0.01 mΩ-100 MΩ), Tensile tester, Differential scanning calorimeter DSC (Q10) and SEM respectively. Also antimicrobial efficiency test (ASTM E2149-10) was done against to Staphylococcus aureus bacteria. It has been seen that breaking strength, conductivity, antimicrobial effect, enthalpy during cyclization increase by use of silver nano-particles while the diameter of nano-fiber decreases. Keywords—Composite polyacrylonitrile nano-fiber, electrical conductivity, electrospinning, mechanical and thermal properties, silver nano-particles.

Size controllable synthesis of ultrafine spherical gold particles and their simulation of plasmonic and SERS behaviors

A simple and reproducible way was explored to synthesize quasi-spherical gold particles with different size distributions in water by rapidly adding a mixture solution of HAuCl4, sodium citrate, and a trace amount of silver nitrate. By careful tuning of the reaction parameters, mono-disperse gold particles with the diameter of 5–220nm can be obtained controllably. The particle size of 130nm for the particles film showed the highest SERS activity with the 632.8nm excitation. The theoretical calculations of the UV–vis extinction spectra can be directly compared with experiments by using the discrete-dipole approximation (DDA). Control of nanostructure shape allows optimization of plasmon resonance for molecular detection and spectroscopy.

Green synthesis of dimension-controlled silver nanoparticle–graphene oxide with in situ ultrasonication

A green chemical approach to control the dimensions of Ag nanoparticle-decorated graphene oxide (AgNP–GO) composites was proposed by in situ ultrasonication of a mixture of AgNO3 and GO solution with the assistance of vitamin C acting as an environmentally friendly reducing agent at room temperature. The AgNP–GO composites were characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, Raman spectra and ultraviolet–visible absorption spectra. The results demonstrated that Ag nanoparticles with an average diameter of ∼15nm were uniformly dispersed on the surface of GO nanosheets by in situ ultrasonication of 1min with vitamin C. Increasing the ultrasonication times resulted in Ag nanoparticles with tunable dimensions ranging from 15 to 55nm being formed on the surface of GO nanosheets. The amount of silver nitrate and the ultrasonication time play a key role in the control of the dimension of Ag nanoparticles on GO, and a formation mechanism of the as-prepared AgNP–GO composites is proposed. This study provides a guide to controlling the dimensions of AgNP–GO composites, which may hold promise as advanced materials for various analytical applications such as catalysis, sensors and microchips.

Facile and highly efficient approach for the fabrication of multifunctional silk nanofibers containing hydroxyapatite and silver nanoparticles

In this study, a good combination consisting of electrospun silk fibroin nanofibers incorporated with high-purity hydroxyapatite (HAp) nanoparticles (NPs) and silver NPs is introduced as antimicrobial for tissue engineering applications. The variable pressure field emission scanning electron microscope results confirmed randomly placed nanofibers are produced with highly dispersed HAp and silver NPs in nanofibers after electrospinning. The X-ray diffraction results demonstrated crystalline features of each of the three components used for electrospinning. Moreover, the TEM-EDS analysis confirmed the presence and chemical nature of each component over individual silk nanofiber. The FT-IR analyses was used confirm the different vibration modes caused due to functional groups present in silk fibroin, Hap, and silver NPs. The obtained nanofibers were checked for antimicrobial activity by using two model organisms Escherichia coli and Staphylococcus aureus. Subsequently, the antimicrobial tests have indicated that prepared nanofibers do possess good bactericidal activity. The ability of N,N-dimethylformamide and silk fibroin used to reduce silver nitrate into silver metal was evaluated using MTT assay. The nanofibers were grown in presence of NIH 3T3 fibroblasts, which revealed toxic behavior to fibroblasts at higher concentrations of silver nitrate used in this study. Furthermore, cell attachment studies on nanofibers for 3 and 12 days of incubation time were minutely observed and correlated with the results of MTT assay. The reported results confirmed the high amounts of silver nitrate can lead to toxic effects on viability of fibroblasts and had bad effect in cell attachment.

Synthesis of gold nanostars with tunable morphology and their electrochemical application for hydrogen peroxide sensing

Gold nanostars (AuNSs) with tunable morphology were synthesized by a seed-mediated growth method using poly(diallyldimethylammonium chloride) (PDDA) as stabilizer. The number and length of the branches of the nanostars can be controlled by adjusting the amount of silver nitrate. In addition, the AuNSs exhibit an excellent catalytic effect toward the reduction of hydrogen peroxide (H2O2) in deoxygenated phosphate buffer (pH 7.0). Thus, the PDDA-protected AuNSs were utilized to modify glassy carbon electrode directly for fabricating non-enzymatic H2O2 sensor. The fast amperometric response, low detection limit, wide linear range, good selectivity and long-term stability for the electrochemical detection of H2O2 imply a good performance of the AuNSs based sensor.

Electrical Properties of Starch Based Silver Ion Conducting Solid Biopolymer Electrolyte

In the present study, the electrical and dielectric properties of a solid biopolymer electrolyte system based on starch doped with different amounts of silver nitrate (AgNO3) were analyzed. The electrolyte system was prepared via solution cast technique. Electrical impedance spectroscopy (EIS) measurement for the system was conducted over a frequency range of 50 Hz - 1 MHz at room temperature. It was found that the sample containing 6 wt.% AgNO3 obtained the highest conductivity value of 1.03 × 10-9 S cm-1. The effect of salt concentration on the dielectric properties of the electrolytes was also studied in relation to the conductivity properties. The dielectric studies indicated that the electrolytes in the present study obeyed non-Debye behavior.

Polyester metallisation with electroless silver plating process

In this paper, electroless silver plating process for polyester was reported. The electroless silver plating is basically divided into four stages including pre-cleaning, sensitisation, electroless silver deposition and post-treatment. As the electroless silver plating stage is the key stage in affecting the brilliant appearance and various functional properties such as conductivity and ultra-violet protection, we will study the effect of process variables, i.e. amount of silver nitrate (AgNO3), concentration of ammonium hydroxide (NH4OH), concentration of sodium hydroxide (NaOH) and process temperature, using increased amount of silver in fabric surface as an indicator, for optimising the electroless silver plating process for possible industrial application. Experimental results revealed that amount of silver nitrate (AgNO3)=1.77×10−3 mole; concentration of ammonium hydroxide (NH4OH)=6.25 %; concentration of sodium hydroxide (NaOH)=0.008 g/ml and process temperature=25 °C can give the best electroless silver plating for polyester fabric. The surface characteristics of the electroless silver-plated polyester fabric were evaluated by scanning electron microscope, X-ray photoelectron spectroscopy and X-ray diffraction analysis. Meanwhile, the performance properties of the electroless silver-plated polyester fabric were measured by CIE L*, a* and b* values, conductivity as well as ultraviolet protection. The experimental results would be discussed thoroughly in this paper.

Fabrication and antibacterial properties of silver-coated glass substrate against Escherichia coli, Salmonella typhimurium, and Campylobacter jejuni

The antibacterial effects of silver ion containing film against Escherichia coli, Salmonella typhimurium and Campylobacter jejuni were investigated. Silver nitrate was as used silver source. 0.1, 0.5 and 1.0 mol% concentrations of silver sol were prepared with different amounts of silver nitrate. The silver sol was deposited by spin coating method. The roughness of the film surface was confirmed by atomic force microscopy. Antibacterial experiments demonstrated that silver ion containing film was effective against Escherichia coli, Salmonella typhimurium and Campylobacter jejuni. The morphological changes in the cell wall exposed to silver ion were observed by scanning electron microscope. The transmittance of silver ion containing film on glass substrate decreased as the concentrations of silver ion increased. The mechanical strengths of silver coated glass were slightly enhanced by defect-filling effect of the film. There are lots of bacteria that can cause serious food poisoning in the military equipment and environments. So, the antimicrobial activity of the silver ion containing film showed its potential for use as a coating for medical devices and military equipment.

Localized Surface Plasmon Resonance (LSPR) Biosensor for the Protein Detection

In this paper, we investigate the ability of the gold nanorods (GNRs) to detect some proteins and demonstrate their potential to be used as plasmonic nanobiosensors. The GNRs were synthesized by a two-step seed-mediated growth procedure at room temperature. Firstly, a seed solution of gold nanoparticles was synthesized in the presence of cetyltrimethylammonium bromide surfactant and, subsequently, incorporated with appropriate amount of silver nitrate and tetrachloroauric acid solutions to grow GNRs with average length of 50 nm and diameter of 14 nm. We study the interaction of GNRs with proteins whose molecular weight varies from 6.5 up to 75 kDa. We investigate the resulting solutions by means of UV–vis absorption spectroscopy to determine the effect of the proteins characteristics on the shift of the localized surface plasmon resonance (LSPR). We show that for the case when proteins are in large excess compared to the GNRs concentration, whatever the protein is, the LSPR shift is constant and does not depend on the protein molecular weight. Moreover, we have been able to demonstrate that the sensitivity of such LSPR sensor is around 10–9 M/nm on a concentration range from 10–10 to 10–8 M. Some comparison with finite-difference time-domain simulations have also shown that the number of proteins adsorbed at the GNRs surface is around 40.

Influence of temperature on the photodegradation process using Ag-doped TiO2 nanostructures: Negative impact with the nanofibers

In this study, the influence of the temperature on the photodegradation process using Ag-doped TiO2 nanostructures was investigated. Two morphologies were used; nanoparticles and nanofibers. The nanofibers were synthesized by electrospinning of a sol–gel consisting of titanium isopropoxide, silver nitrate and poly(vinyl acetate). The silver nitrate amount was changed to produce nanofibers having different silver contents. Typically, sol–gels containing 0.5, 1.0, 1.5, 2.0 and 2.5wt% silver nitrate were utilized. Calcination of the electrospun mats at 700°C led to produce well morphology Ag-doped TiO2 nanofibers for all formulations. The nanoparticles were prepared from the same sol–gels, however, instead of spinning the gels were dried, grinded and sintered at 700°C. Photodegradation under UV irradiation for the rhodamine B at 5, 15, 25, 45 and 55°C were performed. For the nanoparticles, increasing the temperature has positive impact as the best degradation was obtained at 55°C. In contrast to the known influence of the temperature on the chemical reactions, in case of the nanofibrous morphology, the temperature has negative impact as the experimental work indicated that the optimum temperature is 25°C. The observed strange effect of the temperature in case of the nanofibrous morphology indicates instant degradation of the dye molecules in the active zones surrounding the nanofibers. Therefore, the increase of temperature results in increase the kinetic energy of the dye molecules so the molecules escape from the active thin film surrounding the photocatalyst. Overall, this study shows that the nanofibrous morphology strongly enhances the surface activity of the photocatalyst which generates negative influence of the temperature.

Core–shell gold/silver nanoparticles: Synthesis and optical properties

Highly dispersed gold–silver core–shell nanoparticles were synthesized in a two-step process. The stabilizer-free gold core particles with an average diameter of ∼30nm were first precipitated by rapid reduction of HAuCl4 with l-ascorbic acid. Thin continuous silver shells of variable thickness were subsequently obtained by reducing controlled amounts of silver nitrate added in the gold sol. The plasmon band of gold gradually blue-shifted and a peak characteristic for silver eventually emerged as the amount of deposited silver increased. A strong and well-defined silver absorption band was recorded when the Ag content exceeded 60wt.%. It is shown that the concentration of Cl− ions in the gold precursor solution plays a critical role in the stability of the bi-metallic sol and the structure of the deposited silver shell.

Controlled synthesis and properties of palladium nanoparticles

In our research, the preparation processes of Pd nanoparticles (Pd NPs) with different methods by adding a certain amount of silver nitrate, iron chloride or sodium iodide are presented in order to control their size and morphology. Various sizes and shapes of Pd NPs are observed by alcohol reduction. The results show the size and morphology control of Pd NPs with chemical reductions of Pd salts by ethanol and ethylene glycol (EG) that have very different reduction processes. The modified polyol method with the gradual addition of Pd and polyvinylpyrollidone precursors in EG at 160°C has led to control their size and morphology in the 10 nm range using 0.02 M AgNO3. It is observed that the Pd nanorod is also formed. The main factors that will control the shapes of Pd NPs have been presented to explain their growth and formation mechanisms in a control process.

Chitosan and silver nanoparticles as pudding with raisins with antimicrobial properties

Chitosan nanoparticles (CS-NP) containing small silver nanoparticles are reported (Ag@CS-NP). CS-NP was synthesized using tripolyphosphate (TPP) as a polyanionic template. TPP also served to electrostatically attract Ag + inside CS-NP, where it was reduced by the terminal glucosamine units of the biopolymer. This procedure is environmental friendly, inexpensive, and permits the synthesis of very small AgNP (0.93–1.7 nm), with only a discrete dependence from the amount of silver nitrate used (5–200 mg). The obtained hybrid nanocomposites Ag@CS-NP were characterized by DLS, HRTEM, and HAADF–STEM presenting a mean hydrodynamic diameter of 78 nm. The antimicrobial activity of Ag@CS-NP against Candida glabrata, Sacharomyces cerevisiae, Escherichia coli, Klebsiella pneumoniae, Salmonella, Staphylococcus aureus, and Bacillus cereus corresponded to MIC values lower than for AgNO 3.

Characterization and Synthesis of Silica-Coated Silver Nanoparticles by Sol-Gel Method with Controlling of Adding Ammonical Silver Nitrate Amount

In this study, silica-coated silver nanoparticles (SSNPs) with a core–shell structure are successfully fabricated using a simple sol-gel method without using primer, surfactant or surface modification of core. To investigate the influence of ammonical silver nitrate (AgNO3) on the synthesis of SSNPs, the amount of an aqueous solution of AgNO3 was varied in the range from 3 to 12 mL. It was found that the thickness of silver shell could be formed in the range of ∼20 to ∼60 nm, and the UV–vis optical absorption measurement revealed a pronounced red-shift of the surface plasmon resonance (SPR) band from 442 to 516 nm.

Micropatterning of Polymer-Embedded Metal Nanoparticles by an Ion Beam Contact Lithography

A convenient and effective method to pattern polymer-embedded metal nanoparticles by ion irradiation has been developed. The thin Pluronic films containing silver nitrate as a precursor of silver nanoparticles were irradiated through a pattern mask with accelerated proton (H+) ions. It was found from the UV-Vis measurement that the formation of silver nanoparticles in the Pluronic matrix was dependant on the amount of silver nitrate. The 50 microm line (pitch 150 microm) patterns of the Pluronic containing silver nanoparticles were obtained with the thin film irradiated to 1 x 10(16) ions/cm2. The heat treatment effect on the morphology of the patterns was investigated by using a scanning electron microscope with an energy dispersive X-ray spectrometer. The results confirmed that the silver nanoparticles were successfully embedded in the Pluronic patterns and the patterns were changed into large silver particles by a heat treatment above 350 degrees C.

Electrospinning of polylactide fibers containing silver nanoparticles

Biodegradable polylactide (PLA) nanofibers containing silver nanoparticles were prepared by electrospinning. Solutions of PLA in dichloromethane/N,N-dimethylacetamide (DMAc) with different amounts of silver nitrate (AgNO3) were used to spin nanofibers. DMAc was used as a reducing agent for Ag+ ions in the PLA solution. In the dilute solution system, the intrinsic viscosity and Huggins constant of the PLA/Ag solutions decreased at AgNO3 concentrations < 6 wt% whereas they increased at 9 wt% AgNO3. On the other hand, dichloromethane/DMAc was found to be a good solvent with a similar solvating power to the Huggins constant results. The solution properties of the viscosity and electrical conductivity of the spinning solutions are strongly affected by the addition of AgNO3. The mean diameters of the PLA/Ag nanofibers containing 0, 3, 6 and 9 wt% of AgNO3 were 400.9±0.1, 352.6±0.3, 313.1±0.2 and 482.8±0.2 nm, respectively. The silver nanoparticles contributed to the formation of thinner PLA/Ag nanofibers. When the PLA nanofibers contained 6 wt% AgNO3, silver nanoparticles with an average size of 4.9 nm were distributed homogeneously in the PLA nanaofibers.

Determination of iodine and bromine in coal and atmospheric particles by inductively coupled plasma mass spectrometry

Bromine and iodine in atmospheric particles or coal can cause environmental problems such as destruction of ozone in the atmosphere; therefore, the presence of these compounds has recently received increased attention. Here, a rapid and reliable method for the simultaneous determination of total bromine and iodine using ICP-MS analysis is described. Samples were dissolved in mixtures of 5 mL of HNO(3) and 2 mL of H(2)O(2) in a high pressure microwave digester. The solution was then oxidized by per-sulfate (Na(2)S(2)O(8)) in addition to a small amount of silver nitrate, after which the total bromine and iodine were measured simultaneously by ICP-MS. The signal memory effects of bromine and iodine during analysis were effectively decreased by washing with a new mixture agent (2% alcohol acidic solution, pH 1-2 adjusted with HCl). The detection limits for bromine and iodine using this method were about 3.2 microg L(-1) and 1.1 microg L(-1), respectively. Additionally, the spike recoveries were between 78.7% and 121% for bromine and iodine analysis, while the relative standard deviations ranged from 4.3% to 9.7%, and from 1.5% to 3.4% for bromine and iodine, respectively. The results of this study indicate that the method described here is suitable for the analysis of micro-amounts of bromine and iodine in atmospheric particles and coal samples.

Synthesis of Monodisperse Quasi-Spherical Gold Nanoparticles in Water via Silver(I)-Assisted Citrate Reduction

We demonstrate a simple and reproducible way to produce quasi-spherical Au nanoparticles (NPs) with a fairly narrow size distribution in water by rapidly adding a mixture solution of HAuCl(4), sodium citrate, and a trace amount of silver nitrate into boiling water. The sizes of quasi-spherical Au NPs obtained increases from 12 +/- 1 nm to 18 +/- 3, 25 +/- 3, and 36 +/- 3 nm with decrease of the citrate concentration in a fairly linear way. The present protocol can efficiently minimize the effect of citrate to buffer the pH of the reaction media and thus change the type and reactive activity of auric ions and significantly speed up the nucleation and growth rate of Au NPs. The presence of Ag(+) ions can not only suppress the secondary nucleation but also reshape the polycrystalline Au NPs into a quasi-spherical shape. In the case of synthesis of Au NPs of sizes ranging from 10 to 36 nm, our approach efficiently makes up the shortages of the classical Turkevich method with respect to the reproducibility and uniformity of the NP size and shape.

Antibacterial electrospun chitosan/poly(vinyl alcohol) nanofibers containing silver nitrate and titanium dioxide

AbstractChitosan/poly(vinyl alcohol) (PVA) nanofibers with antibacterial activity were prepared by the electrospinning of a chitosan/PVA solution with a small amount of silver nitrate (AgNO3) and titanium dioxide (TiO2). Nanofibers with diameters of 270–360 nm were obtained. The yield of low‐viscosity chitosan (LCS)/PVA nanofibers was higher than that of high‐viscosity chitosan (HCS)/PVA, and the water content of the HCS/PVA nanofibers and the LCS/PVA nanofibers were 430 and 390%, respectively. The nanofibers developed in this study exhibited antibacterial activities of 99 and 98% against Staphylococcus aureus and Escherichia coli, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Lewis Acid Catalyzed Addition of Pyrazoles to Alkynes: Selective Synthesis of Double and Single Addition Products

AbstractSilver and zinc salts were found to efficiently catalyze the addition of an N–H bond of pyrazoles to alkynes. With silver triflate as a catalyst, two pyrazoles regioselectively attacked the same carbon atom of the C≡C bond of aliphatic terminal alkynes to give gem‐dipyrazolylalkanes predominantly. Replacement of silver triflate with zinc triflate allows us to achieve double addition of pyrazoles to aromatic terminal alkynes. In contrast to the selective double addition, the corresponding single addition of aliphatic and aromatic terminal alkynes exclusively proceeded in the presence of a catalytic amount of silver nitrate. Internal alkynes also participated in the single addition reaction with the aid of silver triflate as a catalyst. The notable feature of this protocol is the utilization of an addition reaction being optimal from environmental and atom‐economical points of view. The reaction mechanism is also described. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2008)