Specific adsorption of tetraalkylammonium ions on bismuth from nonaqueous solvents

1981 ◽  
Vol 46 (9) ◽  
pp. 2158-2165
Author(s):  
U. Palm ◽  
M. Väärtnŏu ◽  
M. Salve
Keyword(s):  
Double Layer ◽  
Electrical Double Layer ◽  
Aliphatic Alcohols ◽  
Nonaqueous Solvents ◽  
Specific Adsorption ◽  
Tetraalkylammonium Ions ◽  
Tetraalkylammonium Cations ◽  
Capacity Data ◽  
Specific Adsorption Of Ions

A procedure for the calculation of the characteristics of the inner part of the electrical double layer has been elaborated on the basis of the capacity data obtained in the conditions of specific adsorption of ions, accompanied by an increase of the inner layer dimensions. The formulae derived have been verified by studying the specific adsorption of tetraalkylammonium cations from aliphatic alcohols.

Specific adsorption of ions and charge distribution in an electrical double layer

1979 ◽  
Vol 100 (1-2) ◽  
pp. 365-377 ◽  
Author(s):  
B. Damaskin ◽  
L. Kuznetsova ◽  
U. Palm ◽  
M. Väärtnu ◽  
M. Salve
Keyword(s):  
Charge Distribution ◽  
Double Layer ◽  
Electrical Double Layer ◽  
Specific Adsorption ◽  
Specific Adsorption Of Ions

The structure of the electrical double layer in the presence of adsorbed organic molecules

1961 ◽  
Vol 264 (1316) ◽  
pp. 133-144 ◽  
Keyword(s):  
Double Layer ◽  
Electrical Double Layer ◽  
Organic Molecules ◽  
Virial Equation ◽  
Differential Capacity ◽  
Free Energy Of Adsorption ◽  
High Coverage ◽  
Virial Equation Of State ◽  
Capacity Data ◽  
Good Agreement

On the model of the electrical double layer previously proposed by the author, equations are derived for the differential capacity of the metal/electrolyte interface in the presence of organic molecules. It is shown that the equations apply even when ions are specifically adsorbed. A method of calculating the amount of adsorption of the organic species from differential capacity data is outlined and applied to published results for thiourea at the mercury aqueous sodium fluoride interface. It is shown that the results are in good agreement with thermodynamic data. From the calculated adsorption d a ta it is shown that thiourea obeys a virial equation of state but that lateral electrostatic forces are probably negligible except at high coverage. The free energy of adsorption as a function of charge has been evaluated and shown to consist of an electrostatic term and a chemical term which decreases as the electron density of the mercury surface decreases.

The Electrical Double Layer

2004 ◽  
Author(s):  
W. Ronald Fawcett
Keyword(s):  
Double Layer ◽  
Electrical Double Layer ◽  
Silver Chloride ◽  
Mercury Electrode ◽  
Ionic Concentration ◽  
Specific Adsorption ◽  
Point Of Zero Charge ◽  
Voltage Source ◽  
External Voltage ◽  
Silver Silver

In examining the properties of the metal | solution interface, two limiting types of behavior are found, namely, the ideal polarizable interface and the ideally nonpolarizable interface. In the former case, the interface behaves as a capacitor so that charge can be placed on the metal using an external voltage source. This leads to the establishment of an equal and opposite charge on the solution side. The total system in which charge is separated in space is called the electrical double layer and its properties are characterized by electrostatic equilibrium. An electrical double layer exists in general at any interface at which there is a change in dielectric properties. It has an important influence on the structure of the interface and on the kinetics of processes occurring there. The classical example of an ideally polarizable interface is a mercury electrode in an electrolyte solution which does not contain mercury ions, for example, aqueous KCl. The charge on the mercury surface is altered using an external voltage source placed between the polarizable electrode and non-polarizable electrode, for example, a silver | silver chloride electrode in contact with the same solution. Within well-defined limits, the charge can be changed in both the negative and positive directions. When the mercury electrode is positively charged, there is an excess of anions in the solution close to the electrode. The opposite situation occurs when the electrode is negatively charged. An important point of reference is the point of zero charge (PZC), which occurs when the charge on the electrode is exactly zero. The properties of the electrical double layer in solution depend on the nature of the electrolyte and its concentration. In many electrolytes, one or more of the constituent ions are specifically adsorbed at the interface. Specific adsorption implies that the local ionic concentration is determined not just by electrostatic forces but also by specific chemical forces. For example, the larger halide ions are chemisorbed on mercury due to the covalent nature of the interaction between a mercury atom and the anion. Specific adsorption can also result from the hydrophobic nature of an ion.

Sign in / Sign up

Export Citation Format

Share Document