Facile preparation of EDTA-functionalized magnetic chitosan for removal of co(II) from aqueous solutions

In this study, an efficient adsorption and reusable magnetic ligand material (Fe₃O₄@Chitosan-EDTA) was synthesized by binding EDTA dianhydride onto magnetic chitosan, and it was employed in removal of Co(II) from aqueous solution. The maximum adsorption capacity of Co(II) onto Fe₃O₄@CS-EDTA was 48.78 mg/g at pH = 5 (303 K), which is much higher than that of Fe₃O₄@Chitosan as well as chitosan. The kinetics of Co(II) on the Fe₃O₄@CS-EDTA was consistent with the pseudo-second-order model. The equilibrium data were better fit with the Langmuir isothermal model than with the Freundlich isothermal model, suggesting that the adsorption mechanism was chemical monolayer homogeneous adsorption. The thermodynamic data showed that the sorption of Co(II) was spontaneous. Furthermore, after four cycles, the adsorption capacity of Co(II) onto the Fe₃O₄@CS-EDTA still retained 84.5% of the capacity of the fresh adsorbent, indicating that Fe₃O₄@CS-EDTA can be considered a promising recyclable adsorbent to remove heavy-metal ions from wastewater.