Study on the adsorption efficiency and mechanism of Sb(V) in aqueous solutions using enhanced surfactant-modified iron-calcium composite

The presence of Sb(V) in aqueous solutions poses a significant threat to the surrounding environment, and current treatment methods are inadequate. In this study, a magnetic surfactant (CTAB)-modified iron-calcium composite (CTAB-IC) was successfully synthesized using iron-calcium composite as the base material. This novel composite was used for the efficient removal of Sb(V) from textile wastewater solutions. Characterization analyses revealed that the CTAB-IC material exhibits a rich long-prismatic structure and superparamagnetic properties, classifying it as a soft magnetic material. Post-adsorption particle agglomerates were found to comprise Ca, S, and O. Sequential batch experiments demonstrated a maximum adsorption capacity of 54.05 mg/g, with adsorption kinetics data fitting the pseudo-second-order model. The intraparticle diffusion model indicated the presence of multiple diffusion steps during the adsorption process. Additionally, the adsorption of Sb(V) by CTAB-IC was identified as a heterogeneous surface adsorption process, best described by the Freundlich model. The primary adsorption mechanisms involved the formation of surface Ca-O-Sb complexes and inner-sphere Fe-O-Sb complexes, as well as amorphous surface precipitation and electrostatic adsorption. Notably, the treatment of textile wastewater often results in iron-calcium-rich sludge, which is challenging to manage and valorize. This study explored the potential for resource recycling by utilizing CTAB to harness the Fe elements in textile wastewater sludge, thereby promoting waste-to-resource conversion.