Direct determination of traces of silver in mercury by voltammetry at the hanging mercury drop electrode in acetonitrile medium

A direct method for the determination of silver in mercury is described. The sample of mercury is introduced into the container of the hanging mercury drop electrode and the anodic voltammograms are recorded in a 0.1 M lithium perchlorate solution in acetonitrile. The anodic peak of silver obtained under these conditions is well separated from the mercury dissolution current. The peak height is proportional to silver concentration over the wide range 2 × 10^?6 mol dm^?3 (1.6 × 10^?6%) to at least 2.0 × 10^?2 mol dm^?3. No prior separation is needed; the procedure requires less than 20 min. The diffusion coefficient of silver in mercury was determined at several temperatures. It was found that silver in mercury does not form intermetallic compounds with copper, lead, thallium, cadmium, tin and bismuth.     

Carbon monoxide adsorption on palladium electrodes modified with silver adatoms

Adsorption of carbon monoxide on palladium deposits and smooth polycrystalline palladium is studied in conditions of preliminary accumulation of various amounts of adsorbed silver (?_Ag) on them. It is discovered that carbon monoxide undergoes adsorption on palladium as it does on platinum, i.e. at the sites free of adsorbed silver, virtually without forcing out preliminarily adsorbed silver. At small and medium values of ?_Ag in the region of electrodesorption of a mixed layer on palladium, as opposed to Pt/Pt, only two peaks are observed in an anodic voltammetric curve. The nature of the processes that are responsible for the presence of two peaks pertaining to the oxidation of a mixed adsorption layer is discussed.     

Voltammetric determination of traces of silver in some metals after dissolution of the sample in mercury

The general possibility of analysing metals and alloys by dissolution of the sample in mercury and recording the anodic voltammogram is examined for the determination of silver in some metals. In order to obtain good separation of the silver peak from the anodic limit, acetonitrile is used in the supporting electrolyte. If the main component of the sample is more noble than mercury, analysis is simple and takes ? 20 min. Significant amounts of base metals in samples must be removed from the amalgam prior to the anodic stripping; optimum conditions for the removal are given. The detection limits found for the determination of silver in gold and lead and in indium amalgam are 4 × 10^?3, 4 × 10^?4 and 4 × 10^?6 % respectively. Dissolution of the lead button in mercury seems to be a successful alternative to the cupellation procedure. Silver in mercury does not form intermetallic compounds with gold.     

Synthesis of fused tetrahydropyrans by hydroalkoxylation of δ-hydroxy allenes

Fused tetrahydropyrans were synthesized by silver(I)- and mercury(II)-mediated intramolecular hydroalkoxylations of δ-hydroxy allenes installed on a tetrahydropyran template. Cyclization of simple allenes was promoted by silver perchlorate to afford vinyl-substituted trans-fused bis-tetrahydropyrans, whereas cyclization of methyl-substituted allenes at the internal allenic carbon atom was achieved more effectively with a catalytic amount of mercuric triflate rather than with silver salts.     

Electrodeposition of mercury on glassy carbon electrode from very dilute mercury(II) solution

Flameless atomic absorption sepctrometry (AAS) has been applied to the investigation of the electroreduction of mercury at the glassy carbon (GC) electrode in dilute mercury(II) solution. The atomic mercury which is produced by electrolysis is found both in the electrolyte solution and on the electrode. The evaporation experiment combined with the flameless AAS clearly shows that mercury(0) deposits on the GC electrode as metallic mercury and adatoms depending strongly on the concentration of mercury(II) in the solution. The monolayer formation and underpotential deposition cannot be observed in the mercury(II)/GC electrode system.     

Voltammétrie de l'argent par redissolution anodique sur electrode de carbone vitreux et application au dosage de l'argent dans l'uranium et le pluton

Anodic stripping voltammetry of silver on a glassy carbon electrode, and application to the determination of silver in uranium and plutonium.The use of a glassy carbon electrode for the anodic stripping voltammetry of silver, without deposition of a preliminary mercury film is described. The deposition time, scan rate, rotation speed and molarity of the sulfuric solution have been studied; the method is applied to the determination of silver in uranium and plutonium.     

The Investigation of Oscillographic Chronopotentiometry at Silver Disk Electrode and Its Mechanism

A.C.oscillopolarographyintroducedbyHeyrovskyinl94lhasbeendevelopedintoanewfieldofelectroanalyticalchemistry-osciIIographicanaIysis'.Astothedevelopmentofelectrode,thechangefromthedroppingmercuryeIectrode(DME)tothesolidelectrode(thehangingmercurydropelectrodeormercuryfilmelectrode)makesoscillographicanalysisarealpracticalvaIue2.Hencedevelopinganewtypeofelectrodeisimportantfortheprogressofoscillographicanalysis.Thepresentpaperdescribestheinvestigationofoscillographicchrono-potentiometryatsilv…     

Synthesis and properties of a chelating resin containing triazolethiol groups

A macroreticular poly(acrylic acid)-based resin with triazolethiol as the functional group has been synthesized. The stability of the resin in acidic media and the behaviour in sorption and desorption of various metal ions have been investigated and compared with those of the acylthiosemicarbazide resin which is an intermediate in synthesis of the triazolethiol resin. Both resins show high affinity for copper(II) silver, cadmium and mercury(II), and high selectivity for silver and mercury(II) at low pH (1–2), and even at pH 7 if EDTA is present. The triazolethiol resin sorbs metal ions faster than the acylthiosemicarbazide resin does and sorbs mercury(II) from high concentrations of acids and neutral salt solutions. This resin has been applied to the concentration of silver and mercury(II) from sea-water samples by column operation.     

Separation radiochimique rapide des ions argent par reduction sur le mercure

A rapid separation .of silver on mercury is proposed in order to utilize shortlived isotopes for the determination of silver by activation. The conditions allowing quantitative reduction of silver were studied; a. kinetic study showed that after 90 sec, 97% of silver could be transferred to the mercury. The spectrometric analysis of ¹¹⁰Ag was also examined. Only metals with a redox potential greater than that of mercury form amalgams, and under the irradiation conditions these metals produce virtually no activity.     

Surface characterization of electrodeposited silver on activated carbon for bactericidal purposes

The use of an electrochemical reactor operated under different flow conditions to deposit silver from aqueous AgNO(3) solutions and tartaric acid as an organic additive on a commercial activated carbon with ultimate bactericidal applications in water purification processes is presented. The characterization of carbon/silver samples was studied by BET, FTIR, X-ray diffraction, XPS, and SEM techniques. The bactericidal activity of the carbon/silver samples was tested on drinking water samples inoculated with E. coli. A reduction of carbon surface area was detected and was caused by increased amounts of silver deposited on carbon samples. Adherent silver deposits were obtained on the carbon/silver samples. X-ray diffraction studies of carbon with electrodeposited silver showed two different preferential deposition planes, [111] and [220]. The FTIR results confirm the presence of carboxyl, phenolic, quinone, and ether surface groups. The XPS results suggest the formation of Ag(2)O and AgO surface species and confirm the reduction of silver to the metallic form. Antimicrobial activity toward E. coli indicated reductions by up to 7 orders of magnitude in the log CFU/mL in just 10 min contact time and for silver contents of 2.47 wt%.     

New external reagents for the simultaneous microdetermination of carbon,hydrogen and mercury

Non-conventional, extremely cheap and readily available materials, namely zinc plates, pumice granules or polystyrene foam cubes, have been utilized as new external mercury-retentive agents at room temperature for the simultaneous gravimetric microdetermination of mercury, carbon and hydrogen by the rapid straight empty-tube method of Korshun and Klimova. A standard Pregl absorption tube charged with the reagent is connected between the combustion tube and the water-absorption tube. Satisfactory results are obtained for carbon, hydrogen and mercury, and compare reasonably well with those found by using the traditional silver wool or gold sponge under similar conditions. Sulphur or halogen can also be determined simultaneously, as usual.     

Silver based mercury film electrode: Part II. The influence of aging of electrode on the electrode processes of various metal ions

The cyclic voltammetric behaviour of 8 metal ions at solid silver amalgam electrodes prepared by aging of a thin silver based mercury film electrode (SBMFE) and by deposition of silver and mercury on platinum were investigated. It was established that such electrodes behave in relation to some metals (Pb, Bi, Sn) similarly as silver electrodes i.e. the cyclic curves obtained with these electrodes at concentration 10^?3M range show a prepeak-postpeak system corresponding to deposition and dissolution of the monolayer of deposit. On the other hand under the same conditions no prepeaks were observed for cadmium, zinc and thallium. In all cases investigated the heights of anodic stripping peaks were lower on curves obtained with aged SBMFE than on those obtained with fresh SBMFE having a mercury layer 1 μm thick.     

Stripping Chronopotentiometry with Dry‐Preservable Supporting Electrolyte

The determination of some toxic metals by stripping chronopotentiometry with a supporting solution having an unconventional composition has been investigated with the aim of using such components in disposable measuring cells preservable in dry state and quite ready for use, only needing addition of a small volume of sample. The new supporting solution is prepared with a solid strong acid, p‐toluenesulfonic acid, in the place of the inorganic acids commonly used to improve the cation availability. The other components are, as usual, sodium chloride, which fixes the potential of the screen‐printed silver – silver chloride reference electrode, and mercury(II) chloride as the plating agent. This supporting solution has been tested in batch measurements with the mercury film glassy carbon electrode as well as with screen‐printed carbon‐ink electrodes, either with mercury film or bare. The physical shape of the mercury layer electrolytically deposited on screen‐printed carbon‐ink electrodes from a supporting solution containing 0.1 M p‐toluenesulfonic acid and 0.1 M sodium chloride has been investigated by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) microanalysis. In chronopotentiometric stripping p‐toluenesulfonic acid performs as well as the usual inorganic strong acids, particularly in terms of sensitivity. At 0.1 mol dm^?3 it proved very suitable for the determination of toxic metals, in particular lead(II), at levels down to a few μg dm^?3. The overall results appear promising and can open new avenues for preparing disposable cells for on‐field stripping chronopotentiometric determination of toxic metals.     

Geometrical factors in the capacity of the electrical double layer

A method for determination of double layer capacities at silver iodide-solution interfaces is presented. The influence of counterion on capacity is subjected to special study in the present work. Capacities at the silver iodide interface are compared with those at the mercury interface (Grahame) and interpreted in terms of theGouy-Stern double layer model. Some characteristic differences between capacities at mercury and silver iodide interfaces are explained in terms of different structural factors.     

Silver based mercury film electrode: Part IV. Comparison of theoretical and experimental voltammetric results obtained for cadmium

Using the silver based mercury film electrode (SBMFE) and cyclic and stripping voltammetric techniques the behaviour of cadmium has been compared with the behaviour of lead as well as with the predictions of the theory of de Vries and van Dalen. At the SBMFE with film thickness between 0.1 and 2 μm lead behaves with good agreement with theoretical predictions and only at thicknesses higher than 2 μm some deviations occur due to collecting of the excess mercury at the bottom of the wire electrode. On the other hand even at thin film electrodes the behaviour of cadmium deviates significantly from the predictions of the theory. The height of the anodic peak decreases and its width increases; also the displacement of the potentials of both cathodic and anodic peaks is smaller than the values predicted theoretically. The deviations are caused neither by the formation of intermetallic compounds in the bulk of mercury phase nor by the formation of heterogenous cadmium amalgam; they reflect the interaction between cadmium dissolved in mercury and the solid silver amalgam which is the substrate of the mercury film. Owing to the effect discussed the stripping determination of cadmium at SBMFE is characterized by a lower sensitivity and reproducibility.     

Voltammetric study of the behavior of amaranth at a mercury thin film electrode on a silver substrate

The voltammetric behavior of amaranth at a mercury thin film electrode on a silver substrate was studied in this paper. It was found that amaranth gave a sensitive reduction peak with the potential of -0.24 V at pH 4.0 in aqueous solution. The mercury thin film electrode on a silver substrate gave good reproducibility and useful life time. The peak currents depended linearly on the concentrations of amaranth from 0 to 100 ppb.     

Study of Bare and Mercury‐Coated Vibrated Carbon,Gold and Silver Microwire Electrodes for the Determination of Lead and Cadmium in Seawater by Anodic Stripping Voltammetry

Carbon, gold and silver microwires are revisited under vibrated conditions for detection of trace lead and cadmium in seawater. The Pb and Cd peaks fully overlapped on the bare gold and carbon electrodes and partially on the silver electrode. The sensitivity of all three was insufficient for detection in uncontaminated waters. Peak separation was obtained after coating with mercury (Hg). Only the Hg‐coated silver electrode is suitable when preplated. Limits of detection for Pb using the Hg/C and Hg/Ag electrodes (20–40 pM), and Cd (70 pM), are sufficiently low for Pb and Cd detection in seawater.     

Dosage mercurimetrique des thioethers en milieu acetique anhydre: Titrimetric determination of thioethers with mercury(II) perchlorate in anhydrous acetic acid media

(Titrimetric determination of thioethers with mercury(II) perchlorate in anhydrous acetic acid media). Thioethers form mercury(II) complexes which are less stable than the thiol complexes. Potentiometric titrations at the millimolar level are possible with a silver amalgam indicating electrode if mercury(II) perchlorate is used as titrant and the medium is anhydrous acetic acid.     

The coulometric production of iodide ion for titrations of mercury(I.II)

The dynamic behaviour of the silver/silver iodide electrode was studied. Iodide ions can be produced by cathodic polarization of the silver/silver iodide electrode in acidic and neutral media. This technique can be used for coulometric titrations of mercury(I) or mercury(II) both alone and in mixture. At the microequivalent level of mercury the error is less than 2%.     

Versuche zur Anreicherung von Edelmetallspuren in Reinstquecksilber durch partielles Lösen der Matrix

Trace impurities of gold and palladium in metallic mercury can be enriched in a simple way by partially dissolving the sample in nitric acid. Practically the whole trace content of the sample will be collected in the residue. Up to at least 100 g Hg the quantity of the mercury sample has no influence on the trace enrichment. After the partial dissolution of the metal the enriched gold was determined photometrically with Rhodamine B as a reagent, Pd was determined as [PdJ₄]^2? complex. For the analysis of metallic mercury containing 0.5 ppm of Au and 2 ppm of Pd the relative standard deviation is 0.046, respectively 0.037. The limit of detection was found to be at 0.2 ppm for both the elements. Using this method, the enrichment of traces of silver in mercury is not possible.