A new method of evaluation of specific surface area of solids using inverse gas chromatography at infinite dilution

1991 ◽  
Vol 142 (1) ◽  
pp. 232-235 ◽  
Author(s):  
Jacek Jagiello ◽  
Eugène Papirer
Keyword(s):  
Gas Chromatography ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Infinite Dilution ◽  
Inverse Gas Chromatography ◽  
New Method ◽  
Method Of Evaluation

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.

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