Figure 6 shows the breakthrough curves of toluene and water vapor when the binary mixtures of toluene and water were fed over RH-MCM-41 and the silylated material. It is useful to discuss material hydrophobicity. This method is applied from Stelzer et al. The HI is defined as the wt.% of toluene adsorbed, relative to the wt.% of water adsorbed. Consider the
breakthrough period, water generally met breakthrough before toluene did in both tested materials. This indicated that RH-MCM-41 possessed hydrophobic property. Moreover, the concentration of water in the effluent was found to increase more than its inlet concentration while the increasing of toluene effluent concentration did not show the overshooting pattern. It suggested that adsorbed water was replaced and expelled by toluene during the competitive adsorption.