Toward Accurate and Efficient Predictions of Entropy and Gibbs Free Energy of Adsorption of High Nitrogen Compounds on Carbonaceous Materials

2014 ◽  
Vol 118 (9) ◽  
pp. 4774-4783 ◽  
Author(s):  
Andrea Michalkova Scott ◽  
Leonid Gorb ◽  
Elizabeth A. Burns ◽  
Sergey N. Yashkin ◽  
Frances C. Hill ◽  
...  
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Nitrogen Compounds ◽  
Carbonaceous Materials ◽  
High Nitrogen ◽  
Free Energy Of Adsorption

scholarly journals Hysteresis and thermodynamic properties of water sorption in ‘Malagueta’ pepper seeds

2018 ◽  
Vol 22 (9) ◽  
pp. 658-663
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Isneider L. Silva
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Water Sorption ◽  
Water Adsorption ◽  
Gravimetric Method ◽  
Free Energy Of Adsorption ◽  
Adsorption And Desorption ◽  
Moisture Contents ◽  
Compensation Theory

ABSTRACT The objective of this study was to determine hysteresis, enthalpy, entropy, enthalpy-entropy compensation theory and Gibbs free energy for water adsorption and desorption in ‘Malagueta’ pepper seeds. Hygroscopic equilibrium moisture contents were determined by the static gravimetric method, with water activity in the range from 0.29 to 0.90 and temperatures of 30, 40 and 50 °C. The hysteresis of the ‘Malagueta’ pepper seeds reduces with the increase of temperature. Enthalpy, entropy and Gibbs free energy of adsorption and desorption increase with the reduction of the moisture content of the seeds. The enthalpy-entropy compensation theory is valid for the sorption processes. The sorption of water between seeds and the surrounding air is a non-spontaneous process.

Can the Gibbs Free Energy of Adsorption Be Predicted Efficiently and Accurately: An M05-2X DFT Study

2011 ◽  
Vol 115 (11) ◽  
pp. 2423-2430 ◽  
Author(s):  
A. Michalkova ◽  
L. Gorb ◽  
F. Hill ◽  
J. Leszczynski
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Dft Study ◽  
Free Energy Of Adsorption

scholarly journals Porous and adsorption properties of hydrated cement paste

2004 ◽  
Vol 58 (1) ◽  
pp. 6-9 ◽  
Author(s):  
Biljana Marina ◽  
Snezana Brezovska ◽  
Donco Burevski ◽  
Biljana Panova
Keyword(s):  
Mechanical Properties ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
Adsorption Isotherms ◽  
Favorable Effect ◽  
Hydrated Cement ◽  
Free Energy Of Adsorption ◽  
Characteristic Energy ◽  
Cement Pastes ◽  
Hydrated Cement Paste

Adsorption isotherms of benzene on hydrated cement pastes prepared by cement ground with and without the addition of grinding aids, triethanol amine (TEA) and ethylene glycol (EG) were investigated. The adsorption isotherms were interpreted by means of the Dubinin-Astakhov (DA) and Dubinin-Radushkevich-Stoeckli (DRS) equations. The microporous structure of cement gel (C-S-H) in the cement pastes, and changes in the Gibbs free energy of adsorption were determined. The mechanical properties of the cement pastes were also measured. It was evident that pastes with additives had different parameters of the DRS and DA equations: the volume and dimensions of the gel pores, the distribution of the dimensions, the characteristic energy of adsorption, and the change in the Gibbs free energy of adsorption. The mechanical properties were also different. The dispersity of the additive-containing ground cements had a favorable effect on the hydration processes. When applying TEA, it was also necessary to analyze its influence on the chemical behavior of hydration in the starting period.

Oxidized fulvic acid adsorption on activated carbon

2013 ◽  
Vol 14 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Ivan Kozyatnyk ◽  
Joanna Świetlik ◽  
Ursula Raczyk-Stanisławiak ◽  
Nataliya Klymenko ◽  
Jacek Nawrocki
Keyword(s):  
Free Energy ◽  
Activated Carbon ◽  
Organic Carbon ◽  
Gibbs Free Energy ◽  
Chlorine Dioxide ◽  
Fulvic Acids ◽  
Ozone Treatment ◽  
Free Energy Of Adsorption ◽  
Biodegradable Dissolved Organic Carbon ◽  
Oxidative Effect

This study evaluates and compares the parameters of equilibrium adsorption from aqueous solutions of river fulvic acids (FA) and peat fulvic acids. Compared to peat FA, the river FA had lower biodegradable dissolved organic carbon (BDOC). We observed a tendency for correlation between change of Gibbs free energy of adsorption and BDOC value. A chlorination dose of 1.4 mg L−1 did not change FA biodegradability and adsorbability. ClO2 treatment produced similar results; ClO2 had a stronger oxidizing influence on FA with low BDOC than on FA with high BDOC. In general, the oxidative effect of O3 was greater than Cl2 or ClO2 and the oxidative effect of ClO2 was greater than Cl2. Qi–Schideman and modified Freundlich equations well described all isotherms of FA on activated carbon F300. The content of low-adsorbed substances in peat FA decreased in the sequence: initial solution – Cl2 – ClO2 – O3. A similar difference was also seen with BDOC content in FA solutions. For peat FA with high BDOC content, the low-adsorbed fraction transformed to a strong-adsorbed fraction. Chlorination and chlorine dioxide treatment decreased low-adsorbed fraction absorbability, although ozone treatment increased it, which corresponded with a change in BDOC and a change in Gibbs free energy of adsorption. Chlorination and ClO2 treatment increased the non-adsorbable fraction, and ozonation substantially decreased the non-adsorbable part of the FA. Treatment by chlorine and ozone increased the concentration range of the strong-adsorbed fraction; chlorine dioxide did not significantly influence this fraction.

Gibbs free energy of adsorption for biomolecules in ion-exchange systems

1994 ◽  
Vol 52 (2) ◽  
pp. 97-106 ◽  
Author(s):  
Joseph A. Gerstner ◽  
Jeffrey A. Bell ◽  
Steven M. Cramer
Keyword(s):  
Free Energy ◽  
Ion Exchange ◽  
Gibbs Free Energy ◽  
Free Energy Of Adsorption
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