scholarly journals Thermodynamic Analysis of Moisture Adsorption of Taraxacum Officinale’ Powder

2020 ◽  
Vol 12 (2) ◽  
pp. 58-66
Author(s):  
Haytem Moussaoui ◽  
Zakaria Tagnamas ◽  
Younes Bahammou ◽  
Mounir Kouhila ◽  
Ali Idlimam ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Taraxacum Officinale ◽  
Sorption Process ◽  
Gibbs Free Energy Change ◽  
Moisture Adsorption ◽  
Adsorption Phenomenon ◽  
Equilibrium Data ◽  
Physical Principles

This work aims to model the adsorption isotherms and study the essential thermodynamic properties of Taraxacum Officinale’ powder during the moisture adsorption phenomenon at three temperatures 30, 40, and 50°C. The results have been determined by the application of the thermodynamics physical principles to the equilibrium data, which are experimentally measured. The estimated values of the isokinetic and harmonic temperatures and the Gibbs free energy change revealed that the sorption process is non-spontaneous and enthalpy driven.

scholarly journals First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1404
Author(s):  
Yunfei Yang ◽  
Changhao Wang ◽  
Junhao Sun ◽  
Shilei Li ◽  
Wei Liu ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Density Functional ◽  
Vibrational Entropy ◽  
Functional Theory ◽  
Lattice Constants ◽  
The Density Functional Theory ◽  
Ductile Behavior ◽  
Pseudo Potential

In this study, the structural, elastic, and thermodynamic properties of DO19 and L12 structured Co3X (X = W, Mo or both W and Mo) and μ structured Co7X6 were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson’s ratio, the DO19-Co3X, L12-Co3X, and μ-Co7X6 compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L12-Co3X exhibited higher strength and brittleness than DO19-Co3X. Moreover, the quasi-harmonic Debye–Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co3X and Co7X6 compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO19-Co3X and L12-Co7X6, the phase transformation temperatures for DO19-Co3X to L12-Co7X6 were determined and obtained values were noted to match well with the experiment results.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

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.

Theoretical Thermodynamic Analysis and Phase Analysis of AZ91D/Flyash Composites

2014 ◽  
Vol 788 ◽  
pp. 604-607
Author(s):  
Hong Chao Chu ◽  
Si Rong Yu ◽  
Cui Xiang Wang ◽  
Qi Lou
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Minimum Principle ◽  
Solution Treatment ◽  
Entropy Change ◽  
Treatment Temperature ◽  
Free Energy Change ◽  
Energy Change ◽  
Solution Treatment Temperature ◽  
Gibbs Free Energy Change

The thermodynamic calculation is valuable for judging the feasibility of a reaction. In the present paper, the enthalpy change (∆HR), entropy change (∆SR) and Gibbs free energy change (∆GR) among various components in AZ91D Mg alloy-Cenosphere composites (FAC/AZ91D) were calculated. Through the calculation, we obtained the relationships between the Gibbs free energy changes and temperatures. The difficulty degree of every potential reaction could be directly reflected by the correlation curve between the temperature and the Gibbs free energy change. The analysis result provided the theoretical basis for the reaction temperature and the solution treatment temperature of the FAC/AZ91D system. At the same time, the analysis based on the minimum principle of the reaction free energy revealed the final components (MgO, Mg2Si and MgAl2O4), which was partially similar to the result of XRD analysis (MgO, Mg2Si and Mg17Al12).

scholarly journals Rationalisation of the activities of phenolic (vitamin E-type) antioxidants

2003 ◽  
Vol 17 (4) ◽  
pp. 753-762
Author(s):  
Christopher J. Rhodes ◽  
Thuy T. Tran ◽  
Philip Denton ◽  
Harry Morris
Keyword(s):  
Free Energy ◽  
Vitamin E ◽  
Gibbs Free Energy ◽  
State Theory ◽  
Linear Free Energy Relationship ◽  
Free Energies ◽  
Gibbs Free Energy Change ◽  
Linear Free Energy ◽  
Free Energy Of Activation ◽  
Enthalpy And Entropy

Using Transition-State Theory, experimental rate constants, determined over a range of temperatures, for reactions of vitamin E type antioxidants are analysed in terms of their enthalpies and entropies of activation. It is further shown that computational methods may be employed to calculate enthalpies and entropies, and hence Gibbs Free Energies, for the overall reactions. Within the Linear Free Energy Relationship (LFER) assumption, that the Gibbs Free Energy of activation is proportional to the overall Gibbs Free Energy change for the reaction, it is possible to rationalise, and even to predict, the relative contributions of enthalpy and entropy for reactions of interest, involving potential antioxidants.

Gibbs free energy change of a discrete chemical reaction event

2020 ◽  
Vol 152 (8) ◽  
pp. 084116
Author(s):  
Carlos Floyd ◽  
Garegin A. Papoian ◽  
Christopher Jarzynski
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Chemical Reaction ◽  
Free Energy Change ◽  
Energy Change ◽  
Gibbs Free Energy Change ◽  
Reaction Event

Behavior of Intermediate CaTiO3 in Reduction Process of TiO2 by Calcium Vapor

2013 ◽  
Vol 551 ◽  
pp. 25-31 ◽  
Author(s):  
Jin Gang Jia ◽  
Bao Qiang Xu ◽  
Bin Yang ◽  
Dong Sheng Wang ◽  
Heng Xiong ◽  
...  
Keyword(s):  
Free Energy ◽  
Titanium Oxide ◽  
Gibbs Free Energy ◽  
Reduction Process ◽  
Free Energy Change ◽  
Energy Change ◽  
Flow Sheet ◽  
Gibbs Free Energy Change ◽  
Crystal Water ◽  
Calcium Vapor

Preparing titanium powders by calcium vapor reduction of titanium oxide directly is a new way with short flow sheet and CaTiO3 is the very important intermediate compound in this process. In this paper, the behavior of intermediate CaTiO3 in the reduction process of TiO2 was investigated. The thermodynamic calculation indicated that the Gibbs free energy change of the reaction to produce CaTiO3 by CaO and TiO2 was always negative below 1000 °C; The reaction Gibbs free energy change of the calciothermic reduction of CaTiO3 was lower than that of TiO, which would be the most predominant step from TiO2 to Ti. The experimental results showed that CaTiO3 phase derived from the reaction between TiO2 and the reduction by-product CaO, and the reaction between TiO2 and the decomposition product CaO from the additive of CaCl2 with crystal water as well in the calcium vapor reduction process of titanium oxide. But CaTiO3 could be reduced to Ti much easier than that of TiO2 by calcium vapor.

scholarly journals Adsorption Equilibrium and Thermodynamic Analysis of CO2 and CH4 on Qinshui Basin Anthracite

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Xidong Du ◽  
Tengfei Wu ◽  
Fulong Sun ◽  
Zhenkun Hou ◽  
Zhenjian Liu ◽  
...  
Keyword(s):  
Free Energy ◽  
High Temperature ◽  
Thermodynamic Properties ◽  
Adsorption Equilibrium ◽  
Gravimetric Method ◽  
Isosteric Heat ◽  
Coal Surface ◽  
Selectivity Factor ◽  
Gibbs Free Energy Change ◽  
Qinshui Basin

Adsorption isotherms of CH4 and CO2 on Qinshui Basin anthracite were obtained at the temperatures of 283 K, 303 K, and 323 K using the gravimetric method. The feasibility of the displacement of CH4 by injecting CO2 on this anthracite was verified by calculating the selectivity factor of CO2 over CH4 (αCO2/CH4), adsorption affinities, and thermodynamic properties of CH4 and CO2. Results show that the values of αCO2/CH4 are more than 4.0. Henry’s constant (KH) of CH4 is smaller than that of CO2, and CH4 has a weaker affinity with coal surface. As temperature improves, KH of CO2 and CH4 decrease. Gibbs free energy change (ΔG) and surface potential (Ω) of CO2 are more negative than those of CH4, indicating that CO2 adsorption on anthracite is more spontaneous and favorable. The absolute values of Ω and ΔG of CH4 and CO2 increase with pressure rises. Isosteric heat of adsorption (Qst) of CH4 is lower than that of CO2. With increasing loading, Qst and entropy loss (ΔS) of CH4 decrease, while Qst and ΔS of CO2 increase. The higher ΔS of CO2 reveals that the adsorbed CO2 molecules constitute a more stable rearrangement than CH4 molecules. High temperature reduces ΔS of CH4 and CO2.

The Size Dependence of Dissolution Thermodynamics of Nanoparticles

NANO ◽  
2016 ◽  
Vol 11 (09) ◽  
pp. 1650100 ◽  
Author(s):  
Zhi-Qiang Wang ◽  
Yong-Qiang Xue ◽  
Zi-Xiang Cui ◽  
Hui-Juan Duan ◽  
Xiao-Yan Xia
Keyword(s):  
Particle Size ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Average Particle ◽  
Dissolution Enthalpy ◽  
Dissolution Entropy ◽  
Dissolution Thermodynamics ◽  
Dissolution Thermodynamic Properties

Dissolution of nanoparticles is involved in the preparation, research and application of nanomaterials, but there is a surprising difference in dissolution thermodynamics between nanoparticles and the corresponding bulk materials. In the paper, the relations of dissolution thermodynamic properties, equilibrium constant of nanoparticles, respectively, and particle size were derived by introducing interface variables and the surface chemical potential. Experimentally, the solubility of nano-barium sulfate with different average particle sizes at different temperatures were determined by the method of electrical conductivity, obtaining the influencing regularities of particle size on the dissolution thermodynamic properties and the equilibrium constant. The regularities are in accordance with the theory. The results show that there are remarkable effects of particle size of nanoparticles on the dissolution thermodynamic properties and the equilibrium constant; with the decreasing of the size of nanoparticles, the dissolution equilibrium constant increases, while the standard dissolution Gibbs free energy, the standard dissolution enthalpy and the standard dissolution entropy decrease; and the logarithm of the dissolution equilibrium constant, the standard dissolution Gibbs free energy, the standard dissolution enthalpy and the standard dissolution entropy are linearly associated with the reciprocal of particle size, respectively. This new theory provides a quantitative description of nanoparticles dissolution behavior, and has important scientific significance for understanding and predicting of thermodynamic regularity of dissolution concerned in the preparation, researches and applications of nanomaterials.

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