Amount Of Silver Nitrate Research Articles

One-step synthesis of silver nanoparticles by sonication or heating using amphiphilic block copolymer as templates

Block copolymer-supported Ag Nps (nanoparticles) have either a “cherry”-like or “raspberry”-like morphology [Antonietti, et al., Adv. Mater. 7 (1995) 1000–1005] depending on the amount of silver nitrate loading and the external conditions. Sonication favors silver nitrate and polyethyleneimine diffusion; the nucleation sites are well distributed in the micellar cores, so it is easy to form the cherry-like Ag NP colloids. However, when the amount of silver nitrate is decreased, it is heating that induces the formation of raspberry-like Ag NP colloids. The Ag NP colloids were investigated by transmission electron microscopy to demonstrate the nanosize dimensions and the location of the Ag NPs in the micelles. X-ray diffraction was employed to determine the crystal structure of the Ag NPs. UV–vis spectroscopy was employed for further qualitative characterization of the optical properties of Ag NPs.

Adsorption Desulphurization of Gasoline by Silver Loaded onto Modified Activated Carbons

The removal of organosulphur from gasoline by adsorption onto commercial carbon samples loaded with different amounts of silver nitrate was investigated. The pore structures of the samples were characterized by nitrogen adsorption studies, while the structure and chemical property of the samples before and after adsorption were examined and analyzed by XRD, FT-IR and SEM methods, respectively. The results showed that silver formed π-complexes with organic sulphides; the higher the silver loading, the greater the amount adsorbed. However, the adsorption selectivity was poor.

Silver-Catalyzed Benzylation and Allylation Reactions of Tertiary and Secondary Alkyl Halides with Grignard Reagents

Treatment of alkyl halides, including tertiary alkyl bromides, with benzylic or allylic Grignard reagent in the presence of a catalytic amount of silver nitrate in ether yielded the corresponding cross-coupling products in high yields. The coupling reactions of tertiary alkyl halides provide efficient access to quaternary carbon centers.

Antimicrobial cellulose acetate nanofibers containing silver nanoparticles

It was found for the first time that polymer nanofibers containing Ag nanoparticles on their surface could be produced by UV irradiation of polymer nanofibers electrospun with small amounts of silver nitrate (AgNO 3). When the cellulose acetate (CA) nanofibers electrospun from CA solutions with 0.5 wt% of AgNO 3 were irradiated with UV light at 245 nm, Ag nanoparticles were predominantly generated on the surface of the CA nanofibers. The number and size of the Ag nanoparticles were continuously increased up to 240 min. The Ag + ions and Ag clusters diffused and aggregated on the surface of the CA nanofibers during the UV irradiation. The Ag nanoparticles with an average size of 21 nm exhibited strong antimicrobial activity.

Evaluation of a standardized method for determining soluble silver in workplace air samples

Several occupational exposure limits and guidelines exist for silver, but the values for each depend on the chemical form of the silver compound in question. In the past, it generally was not possible, without prior knowledge of the work process, to distinguish soluble silver from insoluble silver compounds collected in workplace air samples. Therefore, analytical results were historically reported as total silver. In this study, work was conducted to evaluate a method to differentiate between the quantities of water-soluble silver compounds and total silver collected on filters. The investigation entailed an evaluation of an International Organization for Standardization method to determine soluble silver in airborne particulate matter. The study design incorporated laboratory experiments to evaluate analytical figures of merit, such as selection of appropriate filter media and extraction solution, analytical recovery, and sample stability during storage. Polytetrafluoroethylene (PTFE) filters (2 microm, 37 mm) in opaque cassettes were either spiked with known amounts of silver nitrate or contained a known mass of solid silver nitrate. Results showed that over 90% of the silver was recovered from PTFE filters. Also, field studies were conducted in which workplace air samples were collected in two silver refineries. Some of these samples were analyzed only for soluble silver while others were sequentially extracted and analyzed, first, for soluble silver, then for total silver. The mass fractions of soluble silver, as compared to total silver, were approximately 2% or less. This investigation served to validate an international standard procedure for the determination of soluble silver in workplace air samples.

Preparation of Antimicrobial Ultrafine Cellulose Acetate Fibers with Silver Nanoparticles

AbstractSummary: A feasible method for the preparation of antimicrobial ultrafine fibers with silver nanoparticles was developed by direct electrospinning of a cellulose acetate (CA) solution with small amounts of silver nitrate followed by photoreduction. Silver nanoparticles in ultrafine CA fibers were stabilized by interactions with carbonyl oxygen atoms in CA. Ultrafine CA fibers with silver nanoparticles showed very strong antimicrobial activity.TEM image of an ultrafine CA fiber electrospun from 10 wt.‐% CA solution with 0.5 wt.‐% AgNO3.magnified imageTEM image of an ultrafine CA fiber electrospun from 10 wt.‐% CA solution with 0.5 wt.‐% AgNO3.

Formation of silver bromide precipitate of nanoparticles in a single microemulsion utilizing the surfactant counterion

Silver bromide precipitate of nanoparticles was prepared by addition of silver nitrate aqueous solution to a single microemulsion system consisting of dioctyldimethylammonium bromide, n-decanol, and water in isooctane. The silver ion reacted readily with the surfactant counterion, bromide, to form the precipitate of nanoparticles, which was stabilized in the water pools. The use of the surfactant counterion as a reactant is a new approach to nanoparticle preparation in microemulsions. It is characterized by high reactivity and less dependency on the intermicellar exchange of solubilizate. The effects of the surfactant and the cosurfactant concentrations, the amount of silver nitrate, and the water to surfactant mole ratio, R, were evaluated. Increasing the surfactant concentration at fixed R and amount of silver nitrate enhanced the role of intermicellar nucleation and resulted in the formation of larger particles, while increasing the amount of silver nitrate at fixed values of all the other variables enhanced the direct nucleation and resulted in the formation of smaller particles. Particle aggregation and flocculation took place when the concentration of n-decanol or the value of R was increased. Particle aggregation and flocculation were attributed to the decrease in the interaction between the surfactant protective layer and the nanoparticles in the water pools.

Formation of Silver Chloride Nanoparticles in Microemulsions by Direct Precipitation with the Surfactant Counterion

Nanoparticles of silver chloride were prepared by direct precipitation of silver ions with the surfactant counterion in the water pools of microemulsions formed by dioctyldimethylammonium chloride in an organic n-decanol/isooctane phase. This work represents a new concept to form nanoprecipitates using a single reverse micellar system. The net result is a fast reaction with less dependency on the intermicellar exchange of solubilizate. The effects of the surfactant and cosurfactant concentrations, of the mole ratio of water to surfactant, R, and of the loading of silver nitrate were evaluated. Increasing the surfactant concentration at fixed values of R and moles of silver nitrate resulted in a higher dependency on the reverse micellar exchange dynamics and increased the particle size. At high n-decanol concentration, the particle size increased due to decreasing the interaction between the nanoparticles and the stabilizing surfactant layer. Similar results were found at high values of R. Increasing the amount of silver nitrate resulted in the formation of more nuclei, and hence in the production of smaller particles. The trends in the particle size and the size distribution were followed using UV spectrophotometry and transmission electron microscope photographs.

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.

Preparation and characterization of trilobal activated carbon fibers

The objective of this research was to evaluate the effectiveness of several different methods for controlling the pore size and pore size distribution in activated carbon fibers. Variables studied included fiber shape, activation time, and the addition of small amounts of silver nitrate. Pure isotropic pitch and the same isotropic pitch containing 1 wt.% silver were melt spun to form fibers with round and trilobal cross sections. These fibers were then stabilized, carbonized, and activated in carbon dioxide. Field emission scanning electron microscopy (FE SEM), electron dispersive spectra (EDS), and wavelength dispersive spectra (WDS) were used to monitor the size and distribution of the silver particles in the fibers before and after activation. Each of these analyses showed that the distribution of silver particles was extremely uniform before and after activation. The fibers were also weighed before and after activation to determine the percent burn-off. The BET specific surface areas of the activated fibers were determined from N 2 adsorption isotherms measured at −196 °C. The results showed that round and trilobal fibers with equivalent cross-sectional areas yielded similar burn-off values and specific surface areas after activation. Also, activation rates were found to be independent of CO 2 flow rate. The porosity of the activated fibers depended on the total time of activation and the cross-sectional area of fibers. The N 2 adsorption measurements showed that the activated fibers had extremely high specific surface areas (greater than 3000 m 2/g) and high degrees of meso- and macro-porosity. FE SEM was also used to investigate surface texture and size of pore openings on the surfaces of the activated fibers. The photos showed that silver particles generated surface macro- and mesopores, in agreement with the inferences from N 2 adsorption measurements.

Consistent Silver Methods for Demonstrating Basement Membranes, Reticulum, and Fungi

Abstract Modifications of the Jones method for basement membranes and reticulum, the Gomori technique for reticulum, and the methods of Grocott and Churukian for fungi are described. The stock methenamine-silver solution used in the Jones method has been reformulated by reducing the amount of silver nitrate and methenamine. Ethylene glycol has been added to help stabilize the solution. The more dilute sodium borate solution is used in this method to simplify preparation of the working methenamine-silver solution. After the kidney sections are oxidized in 0.5% periodic acid, they are treated with 0.5% thiosemicarbazide. Treatment with thiosemicarbazide accelerates the silver reaction with basement membranes. Gomori's technique for reticulum fibers has been modified to eliminate nonspecific background staining, resulting in better visualization of reticulum. Oxidation with acidified potassium permanganate instead of potassium permanganate is essential for elimination of nonspecific background staining. The ...

Dilute Ammoniacal Silver Solutions for Demonstration of Reticulum and Argentaffin Granules

AbstractThe substitution of 1% silver nitrate for 5 % silver nitrate in reticulum and argentaffin procedures results in equal or better staining. Because less ammonium hydroxide is required in the production of the ammoniacal silver solution, tissue loss associated with the strong arnmoniacal compounds is minimized, as is the danger of producing potentially explosive chemicals. In addition, a significant cost savings can be realized from the reduced amounts of silver nitrate required in the procedures. (The J Histotechnol 13:137, 1990)

The Solubility of Silver Nitrate in Glycerine, Ethylene Glycol and 1,3-Propanediol at 25°C

Abstract The solubility of silver nitrate in the chromatographic support solvents, glycerin, ethylene glycol and 1,3-propanediol has been determined at 25°C, in the absence and presence of 5% water. The solubilities are reported as mole fractions, molality and molarity of silver nitrate. The solubilities in the solvents increase in the order: 1,3-propanediol < ethylene glycol < glycerin. These solubility data allow estimation of the amount of silver nitrate on the column support.

Characterisation and properties of mixed (Ag, Na) polycrystalline beta″-aluminas

Samples of suitable size were cut from small tubes of polycrystalline beta′' alumina, supplied by Ceramatec Inc. The pieces of sodium beta″ alumina were immersed in molten mixtures of sodium nitrate and different amounts of silver nitrate at 350°C for 24 hours to produce mixed (Na, Ag) beta″ aluminas by ion exchange. The sodium and silver content was subsequently determined from the weight change and by chemical analysis. Equilibrium exchange curves were constructed from these data. The specific conductivity of the (Na, Ag) beta″ aluminas was measured by a four-probe technique at 1000 Hz between room temperature and 500°C. Conductivity - composition curves were obtained for different temperatures. The minimum in these curves is interpreted as a combination of the influences of the grain boundaries and the mixed alkali effect.

The Preparation of Stable Silver Sulphide Sols and The İnvestigation of The Flocculation Effects of Different Tecnical Polymers and Salts on These Sols

In this work, silver sulphide sols were prepared by the reaction between dilute silver nit- rate and sodium thiosulfate Solutions. For this purpose, Solutions were mixed in various propor- tions. Their stability w ere determined by ploıting the absorbance values measured at definite time intervals versus time. The mixtures were prepared in two series as follows: (A) Those in which silver nitrate was in excess as compared to silver thiosulfate. (B) Those in which sodium thiosulfate was in excess as compared to silver nitrate. In the cases where reagent concantrations were almost the same it was noted that sols were not stable. They were only stable when different concentrations are used and the most stab¬le silver sulphide sol is obtained when the molar concentration ratio of Na2S2Os to AgNO3 is 1,25 or greater. These are type (B) sols. It was found also that the ratios of concentrations influence the duration of sol formation. Shaking had no effect on such sols. The stabilizing effect of nitrate ions was observed in the sols where the amount of silver nitrate was more than of sodium thiosulfate. Both sols are negatively charged. The flocculating effect of anionic, cationic and non-ionic polymers and aluminium nitrate, barium nitrate salts on the sols on mentioned above were investigated. Aluminium and barium salts had a negligib- Je effect on the (A) type sols. On the other hand, the non-ionic polymers had the most floccula¬ting effect when shaken for five minutes at 170 rpm. (rotasyon per minute). In (B) type sols, aluminium and barium salts act as strong flocculating agents. Anionic, cationic and non-ionic polymers had no flocculating effect on these sols when agitated. The flocculating effect was determined from the curves obtained between the absorbances versus time at definite wavelength. It was conculuded that these sols differed from each other by their stability and flocculation with electrolytes. Micrographs might also show that their partic- les size and shapes also where different.

Silver(I)/persulfate oxidative decarboxylation of carboxylic acids. Arylacetic acid dimerization.

The oxidative decarboxylation of arylacetic acids by sodium persulfate and a catalytic amount of silver nitrate produces benzylic radicals which dimerize cleanly to give 1,2-diarylethanes.

Periodate oxidation analysis of carbohydrates: Part 12. Rapid Determination of Aldehydes in the Oxidation Products of Oligoglycosides by the Dithioacetal Method

A rapid and convenient analysis for glycosidic linkages in oligoglycosides was developed by improving the ditbioacetal method. A sample (0.1–1 μmol) was oxidized with an aqueous or aqueous methanolic 0.05 M solution of sodium metaperiodate for 3 h at 50°C. An equivalent amount of silver nitrate was added and the mixture was evaporated to dryness. The residue was treated with a 2:1 (v/v) mixture of ethanethiol and trifluoroacetic acid for 10 min at 25°C, and subsequently trimethylsilylated with hexamethyldisilazane and trimethylchlorosilane for 30 min at 50°C. Gas chromatography of the product allowed the simultaneous determination of the conjugated aldehydes in the oxidation product with high reproducibility. The glycosidic linkages in various oligoglycosides were examined by this procedure.

A nongravimetric method for the routine determination of chloride in carbonate rocks

The method described depends upon the precipitation of silver chloride from a known amount of silver nitrate followed by the determination by atomic absorption spectroscopy of Ag remaining in solution. The coefficient of variation (ratio of standard deviation to mean) varies from 5.3% at 100 ppm to 1.5% at 900 ppm.

Neutron activation analysis of iodine in blood serum or other biological materials by substoichiometric precipitation of iodine as silver iodide

Several modifications are proposed of the established methods of iodine determination in serum. Prior to the actual analysis, the serum is lyophilized. This preliminary treatment permits the use of large samples. Through lyophilization human blood serum samples can easily be reduced to one-tenth of the original weight. Reduction is even more dramatic with materials from other than human origin. After irradiation the samples are subjected to chemical treatment in the presence of an iodine carrier and131I-labelled thyoxine. This procedure has been adopted for the determination of the iodine content and the chemical yield in one and the same radioactive measurement. The analysis technique itself consists of an open system Schoniger combustion. The open combustion allows the use of large samples; the gases evolved are absorbed upon their subsequent passage through potassium hydroxide and hydrochloric acid; the mineralization requires less than two minutes. After the addition of a substochiometric amount of silver nitrate, silver iodide is precipitated from an ammoniacal solution as a flat sample, which has been found ideally suited for high efficiency counting with a Ge(Li) detector. The spectrum gives evidence of an excellent decontamination from the38Cl,80Br and82Br activities. The iodine content can be calculated from the ratio of the photopeak areas at 364.5 keV and 442.7 keV corresponding to131I and128I, respectively. The chemical procedure requires a mere 15 min, and the recording of the γ-ray spectrum takes no longer than 30 min. The technique is not limited to serum only. It proved well suited for the analysis of many other types of biological material, e.g. human skin tissues.

Mechanism of prophylaxis by silver compounds against infection of burns.

To clarify tthe mechanism by which local application of silver compounds protects burns against infection, an ion-specific electrode was used to measùre the concentration of silver ions in solutions. By this method it was shown that in burn dressings silver ions were reduced to a very low level by precipitation as silver chloride. The antibacterial effect was found to depend on the availability of silver ions from solution in contact with precipitate. Between 10(-5) and 10(-6) molar silver nitrate solution in water was rapidly bactericidal. The minimal amount of silver nitrate causing inhibition of respiration of skin in tissue culture was about 25 times the minimal concentration of silver nitrate that inhibited growth of Pseudomonas aeruginosa.