Effect of EDTA and some other interfering species on the adsorption of Co(II) by EDTA-modified chitosan

• EDTA–chitosan adsorbed effectively Co(II) from the solutions with different interfering species
• EDTA–chitosan could be used in the removal of radioactive Co(II)
• Competition between surface bound EDTA and free EDTA was observed
• Co(II)EDTA containing EDTA–chitosan was successfully stabilized by concrete sealing

The adsorption of Co(II) by EDTA-modified chitosan was studied in the presence of solution phase EDTA and other interfering species. The increasing amount of EDTA inhibited Co(II) adsorption due to the competition between solution phase and surface bound chelating agents. However, Co(II) removal reached 99% from the solutions where all the Co(II) ions were chelated by EDTA. Oxalate, on the other hand, with considerably lower chelating ability than that of EDTA did not affect the adsorption of Co(II). Furthermore, EDTA–chitosan was effective adsorbent for Co(II) in the simulated decontamination solutions and in the solutions traced with radiocobalt 57Co. Both isotherm and kinetic modeling were conducted for pure and EDTA containing Co(II) solutions and the presence of EDTA clearly affected the obtained results. FTIR- and CE-analysis suggested that EDTA–chitosan was able to capture Co(II) from its dissolved EDTA-chelate. Stability of EDTA–chitosan was confirmed by regeneration and column studies.