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.
The heat of immersion and the surface properties of pyrogenic silicas were examined using microcalorimetry and inverse gas chromatography at finite concentration (FC-IGC). The microcalorimetric measurements showed a regular decrease of the heat of immersion, in water, per area unit with an increase in the surface areas. The desorption isotherms were established using FC-IGC. It is observed that BET constant value goes through a minimum, whereas the shapes of distribution function of the adsorption energies of isopropanol are changing. All results could be interpreted using a model of formation of the pyrogenic silica in the flame, which explains the change of surface functionality and geometry occurring around 200 m2/g.
Donnet
Jean-Baptiste
JB
ENSCMu ENSISA-W, 11, rue Werner Mulhouse Cedex, France. JB.Donnet@univ-mulhouse.fr
Balard
Henri
H
Nedjari
Nabila
N
Hamdi
Boualem
B
Barthel
Herbert
H
Gottschalk-Gaudig
Torsten
T