Liquid Chromatography - The Thermogravimetric Analysis of Silica Gel 2
Figure 4. Thermogram of Silica Gel
The first loss of water between 50˚C and 150˚C can be attributed to physically adsorbed water. The second source that is lost between 150˚C and 400˚C appears to be strongly held (probably hydrogen bonded) water. The third and last loss appears to come from the condensation of the silanol groups to siloxane bonds with the elimination of water. The amount of water lost during the three desorption processes shown as desorption curves in figure 34.