Efficient removal of cadmium (II) ions from aqueous solution by CoFe2O4/chitosan and NiFe2O4/chitosan composites as adsorbents.

Magnetically recoverable chitosan based spinel cobalt and nickel ferrite (CS/CoFe2O4 and CS/NiFe2O4, respectively) composites were successfully prepared in one step. A series of batch adsorption experiments indicated that the removal of toxic Cd(II) ions by the as-obtained composites as adsorbents was pH-dependent, rapid, proficient, better fitted to pseudo-second-order kinetics model and Langmuir monolayer adsorption isotherm model. Compared to the naked particles, magnetic bio-polymer composites exhibited promoted adsorption capacity. Competitive adsorption studies in binary solutions illustrated preferable selectivity of adsorbents toward Cd(II) ions in the presence of co-existing cations. More importantly, CS/CoFe2O4 and CS/NiFe2O4 had a satisfactory practical application in the removal of Cd(II) from real groundwater spiked with cadmium. The exhausted adsorbents could be regenerated efficiently by 0.5 M HNO3. The results from this study support that CS/CoFe2O4 and CS/NiFe2O4 prove excellent adsorption behavior for the removal of Cd(II) ions from aqueous media.