The preparation of chitosan beads was according to Adarsh and Madhu (2014). Chitosan (1 g) was dissolved in 100 mL of acetic acid (1% v/v) and stirred constantly until homogenous solution was obtained. The solution was dropped into NaOH solution (2 M) through a burette. The formed beads of chitosan were left in NaOH aqueous solution overnight to neutralize the acid. The beads were washed intensively with distilled water to remove residual NaOH.