Retardation of Cd2+and Zn2+ discharge at the dropping mercury electrode by adsorbed phenyl substituted phosphonium cations

1988 ◽  
Vol 66 (5) ◽  
pp. 1053-1058 ◽  
Author(s):  
A. Anastopoulos ◽  
A. Christodoulou ◽  
I. Moumtzis
Keyword(s):  
Direct Current ◽  
Mercury Electrode ◽  
Capacitance Measurements ◽  
Adsorption Characteristics ◽  
Dropping Mercury Electrode ◽  
Activated Complex ◽  
Phosphonium Cations

The effect of adsorbed propargyltriphenyl- and vinyltriphenylphosphonium cations on the discharge of Cd2+ and Zn2+ at dropping mercury electrode is studied by direct current polarographic measurements. Adsorption characteristics are determined by capacitance measurements. The size parameters of the activated complex and the surfactant particles are derived and an elucidation of the mechanism of the inhibited reaction is attempted.

Direct current polarography in the presence of alternating voltages. II. Irreversible systems

1954 ◽  
Vol 7 (4) ◽  
pp. 312 ◽  
Author(s):  
GS Buchanan ◽  
RL Werner
Keyword(s):  
Direct Current ◽  
Mercury Electrode ◽  
Dropping Mercury Electrode ◽  
Alternating Voltage

The superposition of a small alternating voltage on the normal D.C. voltage applied at the dropping mercury electrode (D.M.E.) results in the case of irreversible systems in a marked displacement of the entire D.C. wave, in contradistinction to those cases known to be reversible. Such a displacement has been interpreted in terms of an ionic picture. The cases examined were ZnO2--, Fe++, Ni++, Sb+++ in the presence of varying concentrations of Cl-, and Cd++ in the presence of varying concentrations of cyclohexanol. The effect of frequency was investigated.

Effect of surface active cations undergoing interfacial rearrangements on deposition type electrode reactions

1988 ◽  
Vol 53 (4) ◽  
pp. 732-742 ◽  
Author(s):  
Anastos Anastopoulos ◽  
Anastasia Christodoulou
Keyword(s):  
Rate Constants ◽  
Mercury Electrode ◽  
Size Ratio ◽  
Inhibition Mechanism ◽  
Electrode Reactions ◽  
Dropping Mercury Electrode ◽  
Surface Active ◽  
Activated Complex ◽  
Effect Of Surface

The influence of the adsorption of methyltriphenyl- and cyclopropyltriphenylphosphonium cations on simple deposition reactions of Cd2+ and Zn2+ at the dropping mercury electrode, is studied by polarographic techniques. The size parameters of the activated complex, r≠, and adsorbate particles, ri, are determined and discussed. It is shown that for substances undergoing interfacial rearrangements, i.e. condensation and reorientation, the values of the size ratio r≠/ri can hardly be correlated to independently determined values of r≠ and ri. Electrode coverages are related to formal rate constants and an elucidation of the inhibition mechanism is attempted.

Time dependent interfacial behaviour of tributylphosphine oxide at the mercury-solution interface

1985 ◽  
Vol 50 (12) ◽  
pp. 2804-2813 ◽  
Author(s):  
Anastos Anastopoulos ◽  
Panaghiotis Nikitas ◽  
Demetrios Jannakoudakis
Keyword(s):  
Mercury Electrode ◽  
Quantitative Description ◽  
Differential Capacitance ◽  
Time Dependent ◽  
Large Drop ◽  
Adsorption Parameters ◽  
Capacitance Measurements ◽  
Dropping Mercury Electrode ◽  
Interfacial Behaviour ◽  
Drop Time

A series of methods are used for the quantitative description of the time dependent interfacial behaviour of tributylphosphine oxide (TBPO). These methods include measurements of the interfacial tension by a capillary electrometer as well as differential capacitance measurements with a dropping mercury electrode (D.M.E.) of short drop times (⪬5 s), a D.M.E. of large drop times (~20 s) and a hanging mercury drop electrode (H.M.D.E.). The capacitance measurements with large drop times reveal the existence of peculiarities during the development of the adsorption film. The adsorption equilibrium of TBPO, at the vicinity of the adsorption maximum, is generally established within times shorter than 10 s. At the region of the adsorption pseudocapacity, time intervals ranging from 200 to 400 seconds are required for the equilibrium. The adsorption parameters derived with the large drop time D.M.E., are in reasonable agreement with those obtained by electrocapillary measurements.

Direct current polarography of the ferrous-ferric oxolate system in the presence of alternating voltages

1958 ◽  
Vol 11 (1) ◽  
pp. 9
Author(s):  
P Beckmann ◽  
GS Buchanan
Keyword(s):  
Direct Current ◽  
Active Substance ◽  
Mercury Electrode ◽  
Surface Active Substance ◽  
Active Materials ◽  
Wave Potential ◽  
Half Wave ◽  
Dropping Mercury Electrode ◽  
Surface Active ◽  
Alternating Voltage

The effect of the superposition of a small alternating voltage on the normal direct voltage applied to the dropping mercury electrode (D.M.E.) was investigated in the case of the ferrous-ferric oxalate system. The wave obtained was of the type found previously for ions which are reversibly reduced at the D.M.E. (e.g. Cd++ etc.). That is, the rectification of the A.C. produced a D.C. wave (the Z wave) which crossed the normal D.C. wave (the Y wave) at the half-wave potential (E�), When surface active materials were added (e.g. cyclohexanol) the reduction became " irreversible " and at certain concentrations of the surface active substance a maximum appeared on the Y wave of a somewhat unusual nature. The effect of a superposed alternating voltage was studied in these cases and it was found that the adsorption of the cyclohexanol was influenced by the presence of the alternating voltage.

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