Synthesis of ethylenediamine modified chitosan microspheres for removal of divalent and hexavalent ions.

Ethylenediamine modified chitosan was obtained in the form of microspheres by chemical crosslinking with gluteraldehyde and evaluated for the effective removal of metal ions. The present modification results in additional nitrogen centers which function as potential binding sites and the microsphere form enhances the specific surface area during adsorption of metal ions. The adsorbent was used in batch experiments to evaluate the adsorption of Cu(II), Zn(II), Pb(II) and Cr(VI) in a individual metal salt solutions. The samples exhibited highest affinity for Cu(II) and least for Cr(VI) ions. The adsorption data were interpreted based on Langmuir and Freundlich isotherm models. The maximum adsorption capacity obtained from Langmuir model is 60.9 mg g(-1). The modified microspheres can be regenerated with high efficiency, suggesting that this adsorbent is satisfactory to reuse.