Adsorption of Co2+ and Sr2+ from aqueous solution by chitosan grafted with EDTA

Abstract The adsorptive removal of Co2+ and Sr2+ from water and wastewater is of great importance for environmental protection. Herein, a cost-effective and efficient adsorbent was reported for both nuclides removal, whilst their adsorption behavior and mechanism were also explored. In single-component systems, the maximum adsorption capacity was estimated to be 61.0 mg g−1 for Co2+ and 8.8 mg g−1 for Sr2+. Over the pH range of 3–7, adsorption capacity of both nuclides was less affected by solution pH level. In Co2+/Sr2+ co-existing system, EDTA-chitosan presented a higher adsorption capacity and affinity towards Co2+ than Sr2+. In multi-components system, EDTA-chitosan was an efficient broad-spectrum adsorbent for many types of metal ions even at a low pH level (pH=1.2). Furthermore, its adsorption affinity was affected by the nature of grafting EDTA fragments and the remaining chitosan fragments. Coordination and electrostatic interaction played a vital role in adsorption process. Above all, EDTA-chitosan is an efficient adsorbent for the adsorptive removal of heavy metal from water and wastewater.