Silica gel adsorbs relatively large quantities of water which was explained on the basis of multi-layer adsorption. This concept was supported by Vleeskens (18,19) and experimentally validated by gravimetric measurements (20). An example of one type of multi-layer adsorption is shown in figure 32.
Figure 32. Multi-Layers of Physically Adsorbed Water
The multi-layer adsorption depicted in figure 32 is much over simplified, as adsorption could also take place the surface of siloxane bonds as well.
