Comparative adsorption of Ni(II) and Cd(II) ions on epichlorohydrin crosslinked chitosan–clay composite beads in aqueous solution

Removal of Ni(II) and Cd(II) by adsorption on epichlorohydrin crosslinked chitosan–clay composite beads was examined in solutions representative of contaminated solutions containing heavy metals. Several important parameters influencing the adsorption of Ni(II) and Cd(II) ions such as contact time, pH, temperature and effect of metal concentration were investigated systematically by batch experiments. Langmuir and Freundlich adsorption models were used to describe adsorption isotherms and constants. The obtained results showed that the equilibrium adsorption behavior of Ni (II) and Cd (II) on epichlorohydrin crosslinked chitosan–clay composite beads could be applied to Langmuir and Freundlich models respectively. Maximum adsorption capacities for Ni(II) and Cd(II) ions were found as 32.36 mg g−1 and 72.31 mg g−1 respectively. The recovery of the metal ions after adsorption and the regeneration of the adsorbent was carried out by treatment of the loaded beads with either 0.1 M HNO3, or 0.01 M EDTA. The adsorbents were characterized by FTIR, SEM and TGA analysis.

► ECH crosslinked chitosan–clay composite beads were prepared.
► It was used to remove of Ni(II) and Cd(II) ions from aqueous solutions.
► Maximum adsorption capacity was found as 72.31 mg g−1 for Cd(II) ions.
► Langmuir isotherm indicated max. adsorption capacity was 32.36 mg g−1 for Ni(II).