Influence of specific surface area of pyrogenic silicas on their heat of immersion in water and on their surface properties assessed using inverse gas chromatography

2008 ◽  
Vol 328 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Jean-Baptiste Donnet ◽  
Henri Balard ◽  
Nabila Nedjari ◽  
Boualem Hamdi ◽  
Herbert Barthel ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Specific Surface ◽  
Surface Area ◽  
Surface Properties ◽  
Specific Surface Area ◽  
Inverse Gas Chromatography ◽  
Heat Of Immersion

Characterization of Silica Xerogels Surfaces by Inverse Gas Chromatography (IGC)

2000 ◽  
Vol 73 (4) ◽  
pp. 634-646 ◽  
Author(s):  
J. B. Donnet ◽  
T. K. Wang ◽  
Y. J. Li ◽  
H. Balard ◽  
G. T. Burns
Keyword(s):  
Gas Chromatography ◽  
Surface Energy ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Inverse Gas Chromatography ◽  
Residual Water ◽  
Silica Xerogels ◽  
Finite Concentration

Abstract Silylated silica xerogels, with controlled specific surface area and porosity, were prepared by a two-step procedure. In the first step, hydrogels were treated “in-situ” with hexamethyldisiloxane (HMDS) in the presence of 2-propanol and acid. In the second step, the hydrophobic gel was transferred into an organic solvent, the residual water removed by azeotropic distillation and the dried xerogel isolated by evaporating the solvent. Using this procedure, structure collapse of the hydrogels was minimized and it was possible to make xerogels with controlled specific surface area and porosity by varying the aging conditions of the hydrogels. The surface properties of both the untreated and the “in-situ” treated silica xerogels were examined by inverse gas chromatography (IGC) at either infinite dilution conditions (IGC-ID) or finite concentration conditions (IGC-FD). The former method was used to monitor the thermodynamic parameters of adsorption of molecular probes in interaction with the sites having the highest energies, while the latter method was used to provide information about the surface energy heterogeneity of the whole surface. The results for the xerogels are also compared to those obtained on untreated and silylated fumed silicas. After silylation, a systematical surface energy decrease has been observed at both ID and FD conditions of IGC for the two types of silica. However, the modified xerogels with higher surface coverage than silylated fumed silica show some different behaviors.

Effect of steaming on physical properties of aluminium hydroxide and aluminium oxide

1990 ◽  
Vol 55 (8) ◽  
pp. 1920-1927 ◽  
Author(s):  
Ro Yong Zun ◽  
Jaroslava Polednová ◽  
Květa Jirátová
Keyword(s):  
Physical Properties ◽  
Partial Pressure ◽  
Specific Surface ◽  
Surface Area ◽  
Water Vapour ◽  
Surface Properties ◽  
Specific Surface Area ◽  
Aluminium Hydroxide ◽  
Aluminium Oxide ◽  
Total Acidity

The effect of partial pressure of water vapour (50-750kPa) in air on physical properties of calcinated aluminium hydroxide AlOOH and aluminium oxide Al2O3 was examined. For both materials it was found that increasing pressure of water vapour leads to a decrease in the specific surface area and to an increase in the diameter of their mesopores. However, changes in the surface properties have not been identical: the total acidity of Al2O3 decreased whereas the acidity of calcinated AlOOH passed through a maximum. The total basicity of Al2O3 increased while that of AlOOH decreased.

scholarly journals Surface properties of low specific surface powders using inverse gas chromatography

2005 ◽  
Vol 157 (1-3) ◽  
pp. 39-47 ◽  
Author(s):  
S. Comte ◽  
R. Calvet ◽  
J.A. Dodds ◽  
H. Balard
Keyword(s):  
Gas Chromatography ◽  
Specific Surface ◽  
Surface Properties ◽  
Inverse Gas Chromatography

scholarly journals Correction of some thermodynamic surface properties of Sodium Alginate determined by Inverse Gas Chromatography

2021 ◽  
Author(s):  
Tayssir Hamieh
Keyword(s):  
Gas Chromatography ◽  
Sodium Alginate ◽  
Surface Area ◽  
Surface Properties ◽  
Inverse Gas Chromatography ◽  
Chemical Engineering ◽  
Specific Enthalpy ◽  
Free Energy Of Adsorption ◽  
Dispersive Component

Abstract In their paper published in the Journal of Chemical Engineering Data, Ugraskan et al. [1] made several inaccuracies in the determination of the surface properties of sodium alginate by using the inverse gas chromatography (IGC) technique. The proposed method to determine the dispersive component of the surface energy, I, cannot be correctly evaluated, because it depends on the surface area of n-alkanes or of methylene group. This surface area supposed by Ugraskan et al. [1] constant strongly depends on the temperature. Therefore, the specific free energy of adsorption, (-ΔGsp), and consequently the specific enthalpy of adsorption, (-ΔHsp), cannot be known with accuracy. The wrong values of (-ΔHsp), certainly lead to inaccurate determination of the acid KA and base KD constants of the solid.

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