The Sorption of Oxygen by Silver

1960 ◽  
Vol 13 (2) ◽  
pp. 210 ◽  
Author(s):  
JA Allen
Keyword(s):  
Surface Tension ◽  
Dissolved Oxygen ◽  
Surface Concentration ◽  
Heats Of Formation ◽  
Temperature Range ◽  
Adsorption Equation ◽  
Gibbs Adsorption Equation ◽  
Adsorption Isobar

The Gibbs adsorption equation has been used in conjunction with surface tension measurements on silver wires to determine the adsorption isobar of oxygen on silver at a pressure of 16 cmHg over the temperature range 650-850 �C. The results show the existence of a surface concentration of oxygen of 2 x 1015 atoms oxygen per cm2. The value of ΔH for the equilibrium between adsorbed and dissolved oxygen has been estimated as 20.6 kcal. This value in conjunction with the heats of formation and solution of Ag2O in silver permit the h3at of adsorption to be determined as 10.5 kcal per g-atom of oxygen.

Ozonation of pine kraft lignin in alkaline solution. Part 2: Surface active properties of the ozonated kraft lignins

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 631-639 ◽  
Author(s):  
Rui Wang ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl
Keyword(s):  
Aqueous Solution ◽  
Surface Tension ◽  
Sodium Chloride ◽  
Synergistic Effect ◽  
Interfacial Tension ◽  
Kraft Lignin ◽  
Average Molecular Mass ◽  
Adsorption Equation ◽  
Gibbs Adsorption Equation ◽  
Dilute Aqueous Solution

Abstract The surface tension and interfacial tension of the F-1000, F-1800, F-5000 and F-15000 fractions obtained by ultrafiltration of the Oz-25-KL, Oz-30-KL and Oz-40-KL preparations (ozonated kraft lignin, KL, preparations with ozone consumption of 25, 30 and 40% per KL) were determined with the concentration range of 1–30 g l-1 at pH of 6, 9 and 11. The surface tension of these ozonated KL preparations decreased with increasing concentration and pH according to the simplified Gibbs adsorption equation for dilute aqueous solution, ∂γ= -RTΓ∂(ln C). The results were discussed in term of functional group contents and weight average molecular mass (Mw) of the ozonated KL preparations. The surface tension of the ozonated KL preparations decreased with increasing carboxylic acid content and, to some extent, phenolic hydroxyl content, but increased with increasing Mw. The synergistic effect of the ozonated KL preparations with a commercial surfactant was then investigated. The oil-water interfacial tension was determined in the ozonated KL preparations in an aqueous solution containing 1.5% Petrostep B-120R and 1.5% sodium chloride with hexane as oil phase by spinning drop technique. The interfacial tension of the system also decreased with increasing the concentration of ozonated KL preparations in the range of 1–16 g l-1 according to the simplified Gibbs adsorption equation. Thus, the addition of a small amount of ozonated KL preparations to the aqueous solution containing 1.5% Petrostep B-120R and 1.5% sodium chloride showed a remarkable synergistic effect on reducing the interfacial tension.

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.

Interface Controlled Diffusional Creep of Cu + 2.8 at.% Co Solid Solution

2012 ◽  
Vol 322 ◽  
pp. 33-39 ◽  
Author(s):  
Sergei Zhevnenko ◽  
Eugene Gershman
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Surface Tension ◽  
High Temperature ◽  
Creep Behavior ◽  
Pure Copper ◽  
Diffusional Creep ◽  
High Temperature Creep ◽  
Temperature Range ◽  
Different Temperatures

High-temperature creep experiments were performed on a Cu-2.8 ат.% Co solid solution. Cylindrical foils of 18 micrometers thickness were used for this purpose. Creep tests were performed in a hydrogen atmosphere in the temperature range of about from 1233 K to 1343 K and at stresses lower than 0.25 MPa. For comparison, a foil of pure copper and Cu-20 at.% Ni solid solution were investigated on high temperature creep. Measurements on the Cu foil showed classical diffusional creep behavior. The activation energy of creep was defined and turned out to be equal 203 kJ/mol, which is close to the activation energy of bulk self-diffusion of copper. There was a significant increase in activation energy for the Cu-20 at.% Ni solid solution. Its activation energy was about 273 kJ/mol. The creep behavior of Cu-Co solid solution was more complicated. There were two stages of diffusional creep at different temperatures. The extremely large activation energy (about 480 kJ/mol) was determined at relatively low temperature and a small activation energy (about 105 kJ/mol) was found at high temperatures. The creep rate of Cu-Co solid solution was lower than that of pure copper at all temperatures. In addition, the free surface tension of Cu-2.8 ат.% Co was measured at different temperatures from 1242 K to 1352 K. The surface tension increases in this temperature range from 1.6 N/m to 1.75 N/m. There were no features on the temperature dependence of the surface tension.

Sign in / Sign up

Export Citation Format

Share Document