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 298K, 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. (C) 2011 Elsevier B.V. All rights reserved.