Silver In Aqueous Solution Research Articles

SBA-Pr-IS-MN-DM: a new fluorescent chemosensor for trace detection of silver in aqueous solutions

Initially, SBA-Propyl-Isatin-Malononitrile (SBA-Pr-IS-MN) was prepared by the reaction of SBA-Pr-Cl with IS-MN, which was synthesized by the reaction of isatin and malononitrile. This organic and inorganic hybrid material can be functionalized by the sequential reaction with dimedone to obtain the target product SBA-Pr-Is-MN-DM, which was investigated as a chemosensor by fluorescence spectroscopy to detect trace amount of Ag+ among several other cations in aqueous media.

Kinetics and Mechanism of Silver Dissolution in Aqueous Sodium Nitrate

The kinetics of the electrochemical oxidation–reduction of silver in aqueous solutions of sodium nitrate was studied by potentiometry. The effect of the electrolyte concentration and temperature and sweep rate on the electrochemical behavior of silver was studied. To characterize the mechanism of silver electrooxidation, the following kinetic parameters were calculated: ion transport number (αn), diffusion coefficient (D), heterogeneous rate constant of the electrode process (Ks), and effective activation energy of the process (Eef). The data obtained may be of interest to specialists in the field of electrochemistry.

Substituting Copper with Silver in the BiMOCh Layered Compounds (M = Cu or Ag; Ch = S, Se, or Te): Crystal, Electronic Structure, and Optoelectronic Properties

The synthesis of BiAgOCh (Ch = S or Se) compounds has been successfully achieved via the ion exchange of copper with silver in aqueous solutions, starting from the copper parent phase. Optical and electrical measurements of BiAgOCh powders confirm an increase in both the bandgap and the electrical resistivity, as compared to those of the copper compounds. The structure of the BiAgOS phase has been clearly examined. X-ray diffraction synchrotron measurements coupled with advanced high-resolution transmission electron microscopy analysis evidenced a Ag-deficient structure, as well as Bi-rich defects, both types of defects being oppositively charged. Silver atoms are also found in interstial sites, which explains the two-dimensional ionic conductivity. This structural study combined with theoretical calculations explains the intrinsic conductivity behavior of these semiconductors linked to the mutual compensation of both defect types in the structure and to the increase in the hole effective mass. This study...

Control of the Size of Silver Nanoparticles and Release of Silver in Heat Treated SiO₂-Ag Composite Powders.

The growth of silver nanoparticles, the activation energy for silver particle growth, and the release of silver species in heat treated -Ag composite powders are investigated. The silver particle growth is controlled by heat treatment for 75 min of the as-synthesized -Ag composite powder at 300–800 °C. During heat treatment the mean size of the Ag particles increases from 10 nm up to 61 nm with increasing temperature, however, the particle size distribution widens and the mean size increases with increasing heat treatment temperature. Based on X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) studies, silver particles are crystalline and in a metallic state after annealing in all -Ag composite powders. The growth of Ag particles is suggested to take place via diffusion and Ostwald ripening. The activation energy for particle growth was determined as 0.14 eV. The dissolution of silver in aqueous solutions from the -Ag composites heat treated, at 300 °C, 600 °C, and 700 °C, was investigated by varying pH and temperature. The dissolution was reduced in all conditions with increasing silver particle size, i.e., when the total surface area of Ag particles is reduced. It is suggested that the dissolution of silver from the composite powders can conveniently be adjusted by controlling the Ag particle size by the heat treatment of the composite powder.

Pourbaix Diagram에 의거한 은(銀)의 회수반응(回收反應)에 미치는 온도영향(溫度影響)

온도에 따른 Pourbaix Diagram 을 열역학 계산에 의해 구성하여 수용액 상 은의 회수반응에 미치는 온도의 영향을 파악하였다. 온도의 상승에 따라 물의 안정성은 pH 변화에 대해 더 크게 영향을 받으며 <TEX>${Ag^+}_{(aq)}$</TEX>의 안정영역은 감소하는 것으로 나타났다. 온도가 하강함에 따라 <TEX>$Ag_{(aq)}$</TEX>를 <TEX>$Ag_{(s)}$</TEX> 및 <TEX>$Ag_2O_{3(s)}$</TEX> 형태로 회수하고 온도 상승 시에는 <TEX>$Ag_{(aq)}$</TEX>를 <TEX>$Ag_2O_{(s)}$</TEX> 및 <TEX>$Ag_2O_{2(s)}$</TEX>의 형태로 회수하는 것이 화학반응상 보다 유리할 것으로 고찰되었다. <TEX>$pH{\leq}2$</TEX> 이하의 강산성 영역에서는 온도 상승에 따른 은 회수 효율성이 감소하고 pH가 2 이상인 조건에서는 온도 증가에 따라 은의 회수 효율성이 증대될 것으로 파악되었다. 또한, 은을 원소 상태로 회수하는 방안은 산화은 형태로 회수하는 방안에 비해 온도변화에 대해 더욱 민감하게 영향을 받는 것으로 고려되었다. The Influence of temperature on the recovery reaction of silver in aqueous solution was investigated based on Pourbaix diagram constructed by thermodynamic calculation at different temperatures. It was observed that the stability of water is more strongly affected by pH variation and the stable region of <TEX>${Ag^+}_{(aq)}$</TEX> is diminished at higher temperature. It was shown that the recovery of <TEX>$Ag_{(aq)}$</TEX> in the forms of <TEX>$Ag_{(s)}$</TEX> and <TEX>$Ag_2O_{3(s)}$</TEX> is more advantageous thermodynamically at lower temperature, however, the recovery of <TEX>$Ag_{(aq)}$</TEX> in the forms of <TEX>$Ag_2O_{(s)}$</TEX> 및 <TEX>$Ag_2O_{2(s)}$</TEX> is more advantageous as temperature increases. The rise of temperature is considered to demote the recovery of silver thermodynamically in strong acidic condition (<TEX>$pH{\leq}2$</TEX>), but more silver is regarded to be recovered with temperature above pH 2. Finally, The recovery of silver in the elemental state is shown to be more sensitively influenced by temperature variation compared with the recovery of silver in its oxide form.

Challenges associated with in-situ TEM in environmental systems: The case of silver in aqueous solutions

This work characterizes the effects of an electron beam on inducing microstructural evolution in Ag during environmental transmission electron microscopy. Two different processes, dissolution of Ag and deposition of Ag under the beam, were observed under different experimental conditions. The former primarily results from ionization induced by the primary beam and the latter primarily results from reduction of Ag+ ions in solution by secondary electrons generated in the substrate. The relative rates vary with the activity of silver in solution and beam current density. A simple model based on chemical kinetics describes the general response of the system as a function of beam current density and solution composition.

Laser Ablation of Silver in Aqueous Solutions of Organic Species: Probing Ag Nanoparticle−Adsorbate Systems Evolution by Surface-Enhanced Raman and Surface Plasmon Extinction Spectra

Laser ablation (LA) of a Ag target in aqueous solutions of some strongly adsorbing ions resulted in formation of chemically modified Ag nanoparticles (NPs). A prospective development of this approach into a one-pot synthesis of hybrid Ag NPs−organic species systems is conditioned by assessment of the factors affecting the hybrid system formation and stability during LA. In this study, intermittent LA of a Ag target accompanied by fragmentation of growing Ag NPs was carried out in aqueous solutions of 2,2′-bipyridine and/or of a cationic free-base porphyrin with nanosecond laser pulses of 1064 and 532 nm wavelengths. Ag NP/organic adsorbate systems resulting from each of the individual stages of the LA process were probed by SERS (surface-enhanced Raman scattering) and SPE (surface plasmon extinction) spectral measurements. The morphologies of selected systems were visualized by TEM (transmission electron microscopy). The efficiency of Ag NP fragmentation during LA (which corresponds to the efficiency of l...

Radiometric and voltammetric study of benzoic acid adsorption on a polycrystalline silver electrode

Adsorption of benzoic acid was studied on polycrystalline silver electrodes in a 0.1 M perchloric acid solution. The electrodes were obtained by electroplating of Ag-black onto a vacuum-deposited silver substrate. The real surface area of such prepared electrodes was calculated from a total capacitance of the electric double layer, determined from the plot of the voltammetric double-layer charging current as a function of the scan rate. Quantitative adsorption data for benzoic acid, obtained using the thin-layer radiometric method, indicate that benzoic acid is surface active in the entire range of potentials available to electrochemical studies on silver in aqueous solutions. The Γ vs E plots show that adsorption increases as potential becomes more positive. An overlap of the positive- and negative-going Γ– E plots points to a full reversibility of the surface process, regardless of the potential range. In turn, surface/bulk exchange experiments attest to a reversibility of adsorption with respect to solution concentration. The apparent value of the Gibbs energy of benzoic acid adsorption on an Ag electrode, as estimated from the Langmuir isotherm, is equal to −31 kJ mol −1. A kinetic analysis of the radiometric data suggests that the surface process rather than the diffusion is a rate-determining step of adsorption. The adsorption of benzoic acid on polycrystalline silver is compared with the adsorption of benzoic acid on other transition metals.

Surface tension of silver in different media

By means of electron microscopy, the stability of silver particles in redox buffers has been studied and values of the surface tension of silver in aqueous solution of buffers and a gelatin medium have been determined to be 0.72 J m −2 and 0.68 J m −2, respectively. Using calculations of the binding energy per atom in vacuum, an effective value of 0.86 J m −2 for the surface tension for silver clusters was determined.

Selective removal of silver in the presence of copper, manganese, and zinc in solution by an algal biomass

Abstract The ability of three different algae in selectively removing silver in aqueous solutions, in the presence of copper, manganese, and zinc in solution, and in artificial sea water was investigated. The ability of the algae to remove silver was pH dependent. Selective removal of silver could be achieved at pH 2. Simultaneous multi‐element flame atomic absorption spectrometry facilitated the study of the determination of silver in the presence of other metal ions.

Electrochemical growth of spherical clusters under joint ohmic, diffusion and ion transfer limitations—III

The paper presents the results of an experimental study of the growth kinetics of single silver crystals electrochemically deposited on a platinum substrate. It is shown that the growth mechanism obeys the kinetic law derived for the case of joint ohmic, diffusion and ion transfer limitations in the presence of a specified quantity of supporting electrolyte. Data are obtained for the diffusion coefficient and for the exchange current density of silver in aqueous solution of silver nitrate.

Surface chemistry of colloidal silver in aqueous solution: observations on chemisorption and reactivity

Colloidal silver particles (3-nm diameter) are oxidized in the absence of air by organic and inorganic electron acceptors (such as nitrobenzene, methylviologen, nitropyridine oxide, and hexacyanoferrateIII) when nucleophilic reagents (such as CN- and SH-) are present in the solution. The mechanism of catalyzed metal oxidation proposed previously,2 according to which the interaction of surface atoms with the nucleophiles leads to an excess negative charge in the metal interior which can be picked up by the electron acceptors, explains the observed phenomena. This mechanism contains reversible steps. An experiment is reported in which the reverse sequence of events is observed: chemisorption of Ag(CN)2- on silver particles, producing an excess positive charge inside the particles, followed by complete reduction of the Ag+ ions of the adsorbed complexes by excess electrons that are deposited by a reducing reagent (i.e., organic radicals generated radiolytically). Ag(CN)2- ions in solution are not reduced by radicals. © 1991 American Chemical Society.

Controlled Formation of Quantum Size Metal and Semiconductor Particles from Aqueous Solutions

ABSTRACTPhotochemical and chemical reduction methods are described for the controlled formation of metallic silver in aqueous solutions. The former approach is capable of generally depositing a number of metals. When spherical silver bromide particles are the substrates, the resulting silver coated composite particles exhibit optical absorption spectra which vary with the coat thickness as theoretically predicted. In the case of spherical silica particles of uniform size, it was possible to produce both quantum size silver particles supported on silica, as well as a silver coat of variable thickness, depending on the rate of the deposition process. In addition to silica, substrates such as latex and chromium hydroxide could be used.CdS particles with two different particle diameters (50–200 Å and &lt; 30 Å) were subjected to 308 nm excimer laser irradiation at 77 K, and the subsequent charge carrier processes studied by ESR. Dramatic differences in the ESR signals as a function of decreasing particle size could be observed, consistent with the localization of charge carriers on numerous surface sites.

Continuous Monitoring of Hydrogen Chloride in Combustion Atmospheres and in Air

A continuous analyzer for hydrogen chloride gas, based on a French standard method, has been utilized for measurement of HCl in laboratory-generated combustion atmospheres and in air. The method is based on continuous titra tion of chloride with silver in aqueous solution. The process is monitored by commercially available automated titration equipment, a mass flowmeter and a dedicated Apple IIe microcomputer. Pure HCl in air was monitored in a steady-state flow-through system and compared to sampling by soda lime tubes. Hydrogen chloride in PVC smoke (both flaming and nonflaming combustion conditions) was monitored in both flow-through and static environments, in cluding an apparatus designed for steady-state combustion. The advantages, disadvantages and recommendations for further study of this technique are discussed.

Reagent Foam Test for the Detection and Semiquantitative Determination of Silver in Aqueous Solution

The analytical suitability of dithizone foam for the detection and semiquantitative determination of traces of silver in aqueous solution has been examined. The effect of diverse ions on the detection of silver has been critically investigated. The detection limit of silver by the proposed foam batch and column methods are 0.08 ppm and 10ppb, respectively.

Optical absorption and catalytic activity of subcolloidal and colloidal silver in aqueous solution: A pulse radiolysis study

Silver atoms were formed in aqueous Ag 2SO 4 solution by a pulse of high-energy radiation and the subsequent agglomeration processes were followed by recording the corresponding changes in optical absorption. The first product of agglomeration that possesses the absorption band of colloidal silver in the near ultraviolet has only four reduced silver atoms. The absorption maximum is first located at 378 nm and the absorption coefficient is 2.8 × 10 3 g-atom −1 liter cm −1. With increasing agglomeration, the maximum shifts to 380 nm and the absorption coefficient to 1.5 × 10 3 g-atom −1 liter cm −1. Above an agglomeration number of 12, the position of the maximum and the absorption coefficient do not change anymore. In another series of experiments, solutions containing Ag + as well as Cu 2+ were pulse irradiated. Both Ag 0 and Cu + were initially formed at known concentrations. It is shown that Ag + is reduced by Cu + at the growing silver aggregates. However, the reaction requires a certain size of the latter. The critical size lies in the subcolloidal range at about n = 10. Shifts in the redox potential of the Ag + Ag n system with the agglomeration number n are discussed in order to explain this effect.

Electrochemical reactions of some organic free radicals at colloidal silver in aqueous solution

Electron-transfer processes between simple 1-hydroxyalkyl, 1-ethoxyethyl, and 2-hydroxycyclohexadienyl radicals and metal ions at the surface of colloidal silver are described. C/sub 6/H/sub 6/OH radicals are oxidized by Ag/sup +/ to yield phenol. In the absence of Ag/sup +/, no electron exchange between C/sub 6/H/sub 6/OH and the silver particles takes place. When the silver particles carry a tiny deposit of thallium metal, the C/sub 6/H/sub 6/OH radicals are reduced. Cu/sup +/ (and Cu/sup 2 +/) ions adsorbed on the silver particles oxidize C/sub 6/H/sub 6/OH radicals. However, reduction of C/sub 6/H/sub 6/OH by Cu/sup +/ occurs, if the silver particles are covered with copper metal. 1-Hydroxyalkyl and 2-ethoxyethyl radicals reduce Tl/sup +/ ions in the presence of colloidal silver, but oxidize Tl atoms in homogeneous solution. Water can be decomposed to yield H/sub 2/ by 1-hydroxy-1-methyl and 1-hydroxyethyl, but not by 1-hydroxymethyl, 1-ethoxyethyl, and 2-hydroxycyclohexadienyl radicals. These findings are discussed in terms of standard potentials for the oxidation and reduction of the radicals and in terms of distributions of occupied and unoccupied electronic redox levels in the radicals and the colloidal metal. In these experiments ..gamma.. radiolysis was used to produce the radicals at a controlled rate.

Catalysis of the reduction of thallium(1+) and of dichloromethane by colloidal silver in aqueous solution

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalysis of the reduction of thallium(1+) and of dichloromethane by colloidal silver in aqueous solutionArnim. HengleinCite this: J. Phys. Chem. 1979, 83, 22, 2858–2862Publication Date (Print):November 1, 1979Publication History Published online1 May 2002Published inissue 1 November 1979https://doi.org/10.1021/j100485a011RIGHTS & PERMISSIONSArticle Views123Altmetric-Citations50LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (662 KB) Get e-Alerts

Reactions of organic free radicals at colloidal silver in aqueous solution. Electron pool effect and water decomposition

Organic free radicals of high negative redox potential such as ..cap alpha..-alcohol radicals were found to transfer electrons to colloidal silver particles stabilized by sodium dodecyl sulfate in aqueous solution. The colloidal particles thus became a pool of stored electrons that could reduce water to form hydrogen or react with suitable acceptors in solution. The organic radicals were produced by irradiation, using suitable scavengers for the primary radicals from the radiolysis of the aqueous solvent. The solutions initially contained silver ions at 1 x 10/sup -4/ - 2 x 10/sup -3/ M. At doses below 10/sup 5/ rd, the silver ions were completely reduced to form the colloidal catalyst. In this dose range, the corresponding hydrogen yield amounted to 1 molecule per 100 eV. It increased steeply at higher doses up to 3 molecules per 100 eV. The H/sub 2/ yield decreased with increasing dose rate and with increasing pH in alkaline solutions. It was highest at a concentration of sodium dodecyl sulfate of 1 x 10/sup -3/ M, i.e., far below the critical micelle concentration of this surfactant. Changes in the absorption spectrum of the colloid are attributed to changes in the size of the silver particles upon chargingmore » up with electrons. The competition of radical-colloid reactions with radical-radical deactivation in the bulk of solution or at the surface of the colloidal particles is also discussed. 11 figures.« less

Electronic Property of Photosensitive Film Formation on Silver in Aqueous Solution of Hydrogen Sulphide

Electronic Property of Photosensitive Film Formation on Silver in Aqueous Solution of Hydrogen Sulphide