Thermodynamic Parameters Analysis of MgS Superfine Inclusion in Grain Boundary

2012 ◽  
Vol 217-219 ◽  
pp. 174-178
Author(s):  
Shao Bo Zheng ◽  
Chun Feng Wu ◽  
Cun Bo Yang ◽  
Yue Gong ◽  
Hui Gai Li
Keyword(s):  
Free Energy ◽  
Grain Boundary ◽  
Thermodynamic Parameters ◽  
Gibbs Free Energy ◽  
Free Volume ◽  
Activity Coefficients ◽  
Plate Steel ◽  
Miedema Model ◽  
Free Volume Theory ◽  
Parameters Analysis

Activity coefficients and concentrations of dissolved magnesium and sulfur in grain boundary are two essential parts for the calculation of the Gibbs free energy of MgS superfine inclusion in grain boundary. Activity coefficients of dissolved magnesium and sulfur in grain boundary are gained first by the use of Miedema Model and Free Volume Theory. Concentrations of dissolved magnesium and sulfur in grain boundary of Fe-matrix are gained by Mclean’s equation. At last the Gibbs free energy of MgS in grain boundary is -14.048KJ/mol in E-class ship plate steel at T=1363K. By comparing the values of the Gibbs free energy of MgS in grain boundary and that in grain interior, a conclusion can be come to that MgS superfine inclusions may form in grain boundary instead of in grain interior.

Absorption Equilibrium and Thermodynamics of Fenugreek Yellow Pigment on Macroporous Resins

2011 ◽  
Vol 233-235 ◽  
pp. 91-94
Author(s):  
Feng Han ◽  
Wen Hong Li ◽  
Xuan Tang ◽  
Dong Li
Keyword(s):  
Free Energy ◽  
Thermodynamic Parameters ◽  
Gibbs Free Energy ◽  
Adsorption Equilibrium ◽  
Yellow Pigment ◽  
Adsorption Models ◽  
Freundlich Model ◽  
Langmuir Adsorption ◽  
Macroporous Resins ◽  
Equilibrium Data

The adsorption equilibrium and thermodynamics of pigment extracted from Fenugreek after degumming on macroporous resins was investigated under differentinitial concentrations. The suitability of the Freundlich and Langmuir adsorption models to the equilibrium data was investigated. The model fitness was determined by R2 . Thermodynamic parameters were calculated by the Van’t Hof equation.The results showed that Freundlich model gave a better fit of adsorption isotherms than Langmuir models. The positive value of enthalpy(∆H) indicated that the adsorption was endothermic, the negative value of Gibbs free energy (∆G) showed the spontaneous and favoured nature of adsorption, and the entropy(∆S) was positive.The resins LS-46 showed an effective adsorbtion for Fenugreek yellow pigment.

Activity coefficients and excess Gibbs’ free energy of some binary mixtures formed by p-cresol at 95.23kPa

2007 ◽  
Vol 39 (7) ◽  
pp. 1022-1026 ◽  
Author(s):  
T.E. Vittal Prasad ◽  
N. Venkanna ◽  
Y. Naveen Kumar ◽  
K. Ashok ◽  
N.M. Sirisha ◽  
...  
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Binary Mixtures ◽  
Activity Coefficients ◽  
Excess Gibbs Free Energy

Activity coefficients of NaNO3 in (Mg, Ca, Sr, and Ba)(NO3)2 + H2O systems at 298 K by EMF methods

1993 ◽  
Vol 71 (3) ◽  
pp. 384-389 ◽  
Author(s):  
Stephen N. Smith ◽  
S. Sarada ◽  
Ramamurthy Palepu
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Gibbs Free Energy ◽  
Activity Coefficients ◽  
Interaction Parameters ◽  
Excess Gibbs Free Energy ◽  
Experimental Activity ◽  
Energy Of Mixing ◽  
Total Ionic Strength ◽  
Free Energy Of Mixing

The activity coefficients of NaNO3 in Mg(NO3)2, Ca(NO3)2, Sr(NO3)2 and Ba (NO3)2 were determined at constant total ionic strength of 0.1, 0.5, 0.75, 1.0, 1.5, and 2.0 mol kg−1 at 298 K using EMF methods. The experimental activity coefficients were analyzed using four different formalisms, namely, Reilly–Wood–Robinson, Scatchard, Pitzer, and Harned equations, and the interaction parameters were evaluated. Excess Gibbs free energy of mixing and trace activity coefficients were calculated and the results are discussed.

scholarly journals CMC Determination and Thermodynamic Micellisation Of NPE Surfactant In Aqueous And CH3OH – H2O Solvents

2013 ◽  
Vol 10 (3) ◽  
pp. 1050-1056
Author(s):  
Baghdad Science Journal
Keyword(s):  
Surface Tension ◽  
Free Energy ◽  
Critical Micelle Concentration ◽  
Binary Mixture ◽  
Thermodynamic Parameters ◽  
Gibbs Free Energy ◽  
Standard Gibbs Free Energy ◽  
Good Linearity ◽  
Methanol Solutions ◽  
Compensation Behavior

The critical micelle concentration (CMC) of nonylphenolethoxylate (NPE) surfactant has been determined by measuring the surface tension as a function of the molar concentration of the surfactant in aqueous and binary mixture of water + methanol solutions at a temperature range from 20?C to 35?C. The interfacial parameters ?max, Amin, ?cmc and ?G?ads were calculated. The results indicate that the CMC increases as the temperature increases and that the addition of methanol the CMC decreases. The thermodynamic parameters such as standard Gibbs free energy (?G?), enthalpy (?H?), and entropy (?S?) of micellization were estimated using the change of CMC with temperature. The enthalpy – entropy compensation behavior of the surfactant was evaluated and a good linearity in the compensation plot has been observed.

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