*2.5. Ultra-Sonication of Nano-Bentonite (B)*

Nano-bentonite (B) was dispersed in deionized water in the ratio 1:20 and kept stirring under constant speed with a magnetic stirrer at room temperature. The (B) suspension was ultra-sonicated with an ultrasonic probe for 120 min with 20 s pulse on and 10s pulse off under 20% amplitude by using Branson Digital Ultrasonic Disruptor, Model 450D supplied by ProSciTech (Queensland, Australia). The suspension was filtered and dried in the oven. The dried powder was ground and sieved through a 53-micron sieve for de-agglomeration.
