2.2.2. Physical Treatment by pH Control and Salt Addition of Bentonite(Bent(pH-s))

Firstly, the Bent suspension was prepared by mixing 20 g Bent with 100 mL of distilled water. Next, the suspension was tip-sonicated for 15 min by using the ultrasonic probe. By dropping HNO₃, the pH of the suspension was adjusted until it reached pH 4. Then, the tip-sonication process was continued for another 5 min. Next, the mixture was added with NaCl (0.01 M) and stirred for 5 min. After that, the suspension was washed with hot water (80 °C) and underwent a drying process at 80 °C for 24 h. Finally, the dried sample of physically treated Bent by pH control and salt addition (Bent(pH-s)) was grounded and sieved.