Evaluation of waste materials for cadmium removal: Comparative study of sorption capacity and stability

Cadmium (Cd) is a toxic metal requiring effective immobilization strategies. This study evaluated fly ash, rice husk ash, red mud, and treated bovine bones for Cd removal, comparing their performance to commercial products (ion exchange resin, activated carbon, calcium carbonate, and zeolite). Red mud and treated bones showed removal efficiency comparable to or better than commercial products across varying Cd concentrations. Sequential extraction revealed that treated bones ensured long-term Cd immobilization, with most Cd retained in the residual fraction. These findings emphasize the potential of using waste-derived materials as cost-effective alternatives for the remediation of Cd in water and soil.