Fe-Mn co-embed carbon spheres for aqueous divalent Cd removal

In this study, Fe-Mn co-embed sodium alginate carbon spheres (Fe-Mn/SA-C) were prepared as a cost-effective adsorbent for aqueous Cd(II) removal by a facile pyrolysis method. The morphology and chemical composition of Fe-Mn/SA-C were explored with various characterized techniques. The results indicate that Fe-Mn/SA-C possess porous structures and abundant oxide-based functional groups. Fe-Mn/SA-C exhibits excellent adsorption properties for aqueous Cd(II) and the adsorption process is pH-dependent. The adsorption data could fit pseudo second-order and Langmuir models well, suggesting that chemisorption is a dominant adsorption mechanism and the maximum adsorption capacity is 280.11 mg −1 . Thermodynamic analysis demonstrates that the adsorption is spontaneous and endothermic. The adsorption mechanisms of Cd(II) include the complexation of Cd(II) with oxygen-based functional groups, precipitation, and ion exchange. Finally, the granulated and magnetic Fe-Mn/SA-C is an efficient and practical adsorbent for cadmium-containing wastewater treatment.