Preparation of magnetic modified chitosan and adsorption of Zn2+ from aqueous solutions

The performance of a cross-linked magnetic modified chitosan (CMMC), which has been coated with magnetic fluids and cross-linked with glutaraldehyde, has been investigated for the adsorption of Zn2+ from aqueous solutions. The CMMC with a diameter range of 20–50 nm was prepared. The effects of pH and the contact time for the adsorption have been discussed, and the optimal adsorption conditions for the adsorption of Zn2+ have been obtained. The research results showed that CMMC was highly efficient for fast adsorption of Zn2+ within the first 25 min, and adsorption equilibrium could be achieved in 30 min. Equilibrium studies showed that the data of Zn2+ adsorption followed the Langmuir model. The maximum adsorption capacity for Zn2+ was estimated to be 32.16 mg/g with a Langmuir adsorption equilibrium constant of 0.01 L/mg at 298 K, which demonstrated that the CMMC had obvious efficient adsorption of Zn2+. The CMMC was stable and easily recovered. Moreover, the adsorption rate was about 90% of the initial saturation adsorption capacity after being used five times.