A certain amount of the powdered Fe–Mn binary oxide was then added into the chitosan solution and stirred until a homogenous solution was achieved. After that, the solution was transferred to a 500-ml separatory funnel equipped with a processed 10-ml pipette tip.The solution flowed through the pipette tip and was dispersed into 0.2M NaOH solution to form beads. The resultant beads sat in the NaOH solution for 4–6 h. After filtering, rinsing with deionized water until the filtrate was approximately neutral, and drying at 55 C for 36 h, the beads were kept in a desiccator for further use