Sb(III) Removal by Granular Adsorbent Synthesized with Iron-Containing Water Treatment Residuals and Chitosan

In this study, chitosan and iron-containing water treatment residues were used to prepare a chitosan/Fe-sludge particle adsorbent (CHFS) via the embedding method for Sb(III) removal. Various technologies were applied to characterize the CHFS, and batch experiments were used to investigate its adsorption properties. The results show that CHFS adsorbents are amorphous and have a specific surface area (119.95 m²/g), both beneficial for adsorption. pH and ionic strength have no impact on the adsorption. Sb(III) adsorption on CHFS occurs spontaneously and endothermically. Sb(III) adsorption by CHFS matches the pseudo-second-order kinetic model and the Langmuir model better, with a maximum adsorption capacity of 24.38 mg/g. The primary adsorption mechanism for Sb(III) is the inner sphere complexation between the Sb and Fe-O bond, while other adsorption mechanisms include chelation, pore filling, and hydrogen bonding. This study offers a reference for antimony removal and resource utilization of iron sludge.