The Electroreduction of Periodate Anion in Alkaline Media

1971 ◽  
Vol 49 (16) ◽  
pp. 2657-2663 ◽  
Author(s):  
W. R. Fawcett ◽  
Y. C. Kuo Lee
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Double Layer ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Alkaline Media ◽  
Dropping Mercury Electrode ◽  
Ph Range ◽  
Theoretical Developments

The electroreduction of periodate anion was studied at a dropping mercury electrode in aqueous solutions in the pH range 11–13.3 where the process is markedly affected by the double layer. The electrode reaction was found to be complex, its mechanism depending on both pH and ionic strength. The effects of the double layer on the component reactions are discussed with respect to current theoretical developments.

Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA

1994 ◽  
Vol 59 (6) ◽  
pp. 1311-1318 ◽  
Author(s):  
Ladislav Svoboda ◽  
Petr Vořechovský
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sodium Perchlorate ◽  
Exchange Capacity ◽  
Chloride Ions ◽  
Point Of View ◽  
Alkaline Media ◽  
Ion Exchangers ◽  
Acidic Media ◽  
Cadmium And Lead

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.

Polarography of nickel in concentrated chloride media

1966 ◽  
Vol 19 (8) ◽  
pp. 1343 ◽  
Author(s):  
TM Florence
Keyword(s):  
Ionic Strength ◽  
Graphite Electrode ◽  
Supporting Electrolyte ◽  
Anhydrous Methanol ◽  
Pyrolytic Graphite ◽  
Hydration Number ◽  
Mercury Electrode ◽  
Specific Adsorption ◽  
Dropping Mercury Electrode ◽  
Pyrolytic Graphite Electrode

In concentrated chloride media, nickel is reduced at far more positive potentials than in dilute solutions. The positive shift in half-wave potential increases as the ionic strength is raised, and is also greater when the cation of the supporting electrolyte has a high hydration number. Evidence is presented to show that the reduction in overpotential is due to the formation of a nickel chloride complex, [Ni(H2O)5Cl]+, which has a stoicheiometric stability constant of 0.094 � 0.009 at an ionic strength of 10.0. Spectrophotometric results show that this nickel species is not formed in low ionic strength solutions. In anhydrous methanol saturated with lithium chloride, nickel is present as the tetrachloro complex, [NiCl,]2-, which has similar polarographic behaviour to the monochloro complex. Current-potential curves recorded at a rotated pyrolytic graphite electrode enabled the behaviour of nickel to be studied in the absence of specific adsorption of the chloride ion. Nickel is reduced at more positive potentials at a dropping mercury electrode than at the pyrolytic graphite electrode, and the results indicate that this difference is due to specific adsorption of chloride on the mercury electrode.

Analysis of the Electrode Kinetics of Ni(II) Reduction in Thiocyanate Media on the Dropping Mercury Electrode

2000 ◽  
Vol 65 (3) ◽  
pp. 326-342
Author(s):  
María S. Crespo-Pinilla ◽  
Fernando Mata-Pérez ◽  
Rosa M. Villamañán
Keyword(s):  
Ionic Strength ◽  
Compensation Effect ◽  
Supporting Electrolyte ◽  
Mercury Electrode ◽  
Electrode Kinetics ◽  
Surface Process ◽  
Experimental Conditions ◽  
Dropping Mercury Electrode ◽  
Kinetics Of

A study of two prewaves of the Ni(II)-SCN- system was carried out under the experimental conditions when the influence of electroreduction of SCN- is negligible. Kinetics of Ni(II) reduction in thiocyanate media on the dropping mercury electrode was studied by DC Tast Polarography (DCTP) via determination of Koutecký's parameter χ; the influence of different variables was analyzed. The study of prewaves was performed using various polarographic techniques. Values of χ depend on the SCN- concentration, pH, ionic strength (Ψ-effect) and on the nature of the supporting electrolyte. The number of electrons n, the transfer coefficient α, the stoichiometric number ν, ∆H≠, and ∆S≠ were determined (compensation effect). The first prewave has character of a reaction in the solution, the second prewave is a surface process. Main features of both mechanisms are common: catalytic nature, one-electron step discharge and the rate-determining process between species of opposite charges.

Formation and Properties of Americium Colloids in Aqueous Systems

1981 ◽  
Vol 6 ◽  
Author(s):  
U. Olofsson ◽  
B. Allard ◽  
K. Andersson ◽  
B. Torstenfelt
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Storage Time ◽  
Large Fraction ◽  
Average Charge ◽  
Particle Sizes ◽  
Aqueous Systems ◽  
Ph Range ◽  
And Storage ◽  
Solution Changes

ABSTRACTThe formation and sorption properties of colloidal americium in aqueous solutions have been studied with variations of pH (2–12), ionic strength (0.01–1.0 M NaClO4), americium concentration (10−7 −10−11 M) and storage time (6 h–6 months). A large fraction of the americium is sorbed on the container walls or on Al2O3 in the pH-range 7–11. Around pH 5–8 and at pH above 12 centrifugable fractions (particle sizes greater than 100 nm) are obtained. The fraction formed at pH above 12, which seems to be a true hydroxide colloid, migrates through an A12O3-filled column with very little retention. The average charge of americium species in solution changes from positive values at pH below 7–8 to negative values at pH above 10–11, as indicated from electromigration studies.

Admittance Behavior of Electrode Reaction of Water at a Dropping Mercury Electrode

1971 ◽  
Vol 44 (10) ◽  
pp. 2880-2880 ◽  
Author(s):  
Kiyoshi Matsuda ◽  
Katsuo Takahashi ◽  
Reita Tamamushi
Keyword(s):  
Mercury Electrode ◽  
Electrode Reaction ◽  
Dropping Mercury Electrode

Electrode currents and concentrations for transfer by diffusion and chemical reaction

1968 ◽  
Vol 21 (8) ◽  
pp. 1953
Author(s):  
CHJ Johnson
Keyword(s):  
Weighting Function ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Graphical Form ◽  
Diffusion Field ◽  
Irreversible Reaction ◽  
Definite Integrals ◽  
Reaction Solution ◽  
Stable Species ◽  
Dropping Mercury Electrode

In the present paper we compute the time-dependent diffusion field around an electrode, which may be a plane or a sphere of constant radius, for an electrochemical system in which a single depolarizing species A through a rapid reversible electrode reaction gives rise to a transitory species B which is converted into a stable species C by a slow irreversible reaction solution. The mathematical solution method is such that by suitable choice of variables it is possible to solve the plane and sphere problems in one operation. The functions yielding concentrations and electrode currents are obtained as definite integrals which are evaluated numerically. By appropriate choice of weighting function the present results can be applied to the expanding sphere problem (dropping mercury electrode). The results are consistent with the spirit of the Ilkovic analysis. Numerical results for planar and spherical electrodes are presented in graphical form.

Polarographic and Cyclic Voltammetric Behaviour of Some Azo Compounds Derived from Sulfonamide in DMF-Aqueous Solutions

1992 ◽  
Vol 57 (2) ◽  
pp. 268-275 ◽  
Author(s):  
El-Sayed M. Mabrouk ◽  
Hamada M. Killa ◽  
Abdel Fattah A. Abdel Fattah ◽  
Shalaby A. Yasen
Keyword(s):  
Reaction Mechanism ◽  
Aqueous Solutions ◽  
Kinetic Parameters ◽  
Alkaline Solution ◽  
Electrode Reaction ◽  
Azo Compounds ◽  
Cyclic Voltammetric ◽  
Ph Range

The polarographic and cyclic voltammetric behaviour of (2-hydroxyphenylazo)-4-benzenesulfonamide and some of its derivatives have been studied in Britton-Robinson buffer series containing 30 vol.% of DMF. Over the entire pH range (2-12), the reduction pathway occurs through an irreversible 4-electron step corresponding to the reduction of N=N center to the amine stage. The voltammograms recorded in acidic and alkaline solution at different scan rates exhibit one or two cathodic peaks depending on the substituent and the pH of the medium. The electrode reaction mechanism was suggested, also the kinetic parameters were calculated.

The Influence of N,N'-Dialkylthioureas on the Two-Step Electroreduction of Zn(II) Ions

1998 ◽  
Vol 63 (6) ◽  
pp. 749-760 ◽  
Author(s):  
Grażyna Dalmata
Keyword(s):  
Electron Transfer ◽  
Double Layer ◽  
Rate Constant ◽  
Electrode Surface ◽  
Mercury Electrode ◽  
Impedance Method ◽  
Dropping Mercury Electrode ◽  
Wide Potential ◽  
Orientation Of Molecules

A two-step reduction of Zn(II) ions at the dropping mercury electrode in 1 M NaClO4/0.001 M HClO4 in the presence of N,N'-dialkylthioureas was examined in wide potential and frequency ranges, using the impedance method. The rate constant of the first electron transfer increases with increasing concentration of N,N'-dialkylthioureas, whereas that of the second electron transfer depends largely on the double layer effects, particularly, on the orientation of molecules on the electrode surface.

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