On the Gibbs adsorption equation and diffuse interface models

2002 ◽  
Vol 458 (2021) ◽  
pp. 1129-1149 ◽  
Author(s):  
G. B. McFadden ◽  
A. A. Wheeler
Keyword(s):  
Diffuse Interface ◽  
Interface Models ◽  
Adsorption Equation ◽  
Gibbs Adsorption Equation

Adsorption. The Gibbs Adsorption Equation

2014 ◽  
pp. 127-149
Author(s):  
A.M. Ovrutsky ◽  
A.S. Prokhoda ◽  
M.S. Rasshchupkyna
Keyword(s):  
Adsorption Equation ◽  
Gibbs Adsorption Equation

scholarly journals Some Questionable Approaches in Interfacial Electrochemistry—The Charged State of Adsorbed Species and Their Involvement in Redox Processes

Electrochem ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 104-123 ◽  
Author(s):  
Gyözö G. Láng
Keyword(s):  
Relevant Literature ◽  
Theoretical Interpretation ◽  
Redox Processes ◽  
Chemical Transformations ◽  
Charged State ◽  
Adsorbed Species ◽  
Adsorption Equation ◽  
Redox Partners ◽  
Gibbs Adsorption Equation ◽  
Adsorption Phenomena

On the basis of a survey on the relevant literature it can be stated that some views and approaches concerning the charged state of adsorbed species and the charge transfer processes occurring with them are far from being unambiguous even in some respect they contradict fundamental physical and physicochemical principles. The meaning of the electrosorption valency, the misleading formulation of the Gibbs adsorption equation, and the interpretation of redox processes occurring with adsorbed species, is discussed in detail. It has been concluded that although the electrosorption valency of an adsorbed species as usually defined is an extra-thermodynamic and self-contradictory concept, experimental determined formal partial charge numbers can be a useful tool for scientists investigating adsorption phenomena, since the observed deviation between its value and the charge number of the same species in the solution phase unequivocally indicates a non-simple mechanism of the adsorption process, which should be taken into account in theoretical interpretation of the experimental data. It has been emphasized that the evaluation of voltammetric curves obtained in the presence of adsorbed redox partners requires a cautious analysis of the accompanying chemical transformations. In the framework of a critical analysis it is demonstrated that probably one of the most important sources of the misinterpretations and misunderstandings is the inadequate approach to the concept of electrode charge. The possibility of a general and straightforward presentation of the Gibbs adsorption equation has also been discussed.

scholarly journals THERMODYNAMICALLY CONSISTENT, FRAME INDIFFERENT DIFFUSE INTERFACE MODELS FOR INCOMPRESSIBLE TWO-PHASE FLOWS WITH DIFFERENT DENSITIES

2012 ◽  
Vol 22 (03) ◽  
pp. 1150013 ◽  
Author(s):  
HELMUT ABELS ◽  
HARALD GARCKE ◽  
GÜNTHER GRÜN
Keyword(s):  
Surface Diffusion ◽  
Sharp Interface ◽  
Diffuse Interface ◽  
Momentum Balance ◽  
Two Phase ◽  
Interface Models ◽  
Natural Energy ◽  
Soluble Species ◽  
Sharp Interface Models ◽  
Dissipation Inequalities

A new diffuse interface model for a two-phase flow of two incompressible fluids with different densities is introduced using methods from rational continuum mechanics. The model fulfills local and global dissipation inequalities and is frame indifferent. Moreover, it is generalized to situations with a soluble species. Using the method of matched asymptotic expansions we derive various sharp interface models in the limit when the interfacial thickness tends to zero. Depending on the scaling of the mobility in the diffusion equation, we either derive classical sharp interface models or models where bulk or surface diffusion is possible in the limit. In the latter case a new term resulting from surface diffusion appears in the momentum balance at the interface. Finally, we show that all sharp interface models fulfill natural energy inequalities.

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