Enhanced removal of iodide from aqueous solution by ozonation and subsequent adsorption on Ag-Ag₂O modified on Carbon Spheres

Highlights: • Ag-Ag₂O modified on Carbon Spheres have been synthesized by a facile method. • The removal capacity for iodide from aqueous solution is improved by ozonation. • The proposed adsorption mechanism of Ag-Ag₂O-CSs is verified. • Ag-Ag₂O-CSs exhibit high selectivity and have better adsorption capacity. - Abstract: In this work, Ag-Ag₂O coated on carbon spheres (Ag-Ag₂O-CSs) as an effective adsorbent was successfully synthesized, the morphologies and structure of the as-fabricated composites were characterized through SEM, XRD and XPS. Ozonation and subsequent adsorption on Ag-Ag₂O-CSs was used to removal of iodide from aqueous solution. Furthermore, the ozonation and adsorption process is slightly influenced in the presence of large concentrations of competitive anions, and the Ag-Ag₂O-CSs displayed better adsorption ability at optimum conditions of pH 2.1. The equilibrium isotherms data for iodine adsorption onto Ag-Ag2O-CSs was best fitted with Freundlich isotherm and the adsorption capability was 374. 91 mg/g. The adsorption kinetics followed the pseudo-second-order kinetics. The thermodynamic have revealed that the adsorption process is endothermic and favorable.