Table 2 shows the hydrophobicity indices of studied materials along with the adsorption amount of both water
and toluene. Considering silylated samples with low silylating concentration (samples of T1-1 and T1-6), it was
found that they adsorbed water less than but they adsorbed toluene more than RH-MCM-41. This provided the higher
hydrophobic property (HI) to modified RH-MCM-41. A sample (T9-24) under higher silylating concentration and
aging time also behaved with better hydrophobicity; even less adsorption of toluene was shown. This might be that
the higher silylating conditions had less surface area as presented before. Besides, high concentration and aging time had little effect to HI; therefore, a condition of 1 wt.% and 1 h was optimized.