Silica gel beads (Si) were heated at 110 C for 1 h to activate the
surface.
20 g of silica was immersed in 30 mL of distilled water tomake slurry.
4 g of chitosan was dissolved in (2%, v/v) acetic acid aqueous solution and stirred for 1 h.
This solution was added to the slurry and the mixture was stirred for 30 min.
5% of glutaraldehyde aqueous solution at a 40:1 volume ratio of chitosan solution was added and stirred vigorously for 5 min.
The mixture was stirred for 2 h and soaked in an ultrasonic bath for 30 min.
The wet bead mixture was transferred to a refrigerator at 4 C for 24 h to
undergo complete cross-linking reaction and washed to neutral pH
and dried in oven at 50 C and used for the sorption studies.