2.2. Preparation of Hydrophobized Silica Gel

Typically, 2 g silica gel was suspended in 10 mL cyclohexane in a beaker, and then 1 mL trichloro(octadecyl)silane in cyclohexane solution (1 M) was added dropwise to the beaker. The reaction mixture was aged for 30 min at room temperature to form a hydrophobic surface on the silica gel. The modified silica gel was separated by filtration and washed three times with 15 mL cyclohexane. It was then dried in an oven overnight at 60 °C and stored in a sealed vial for further use.