Synthesis and Study of Kinetics of CoFe ₂ O ₄ @SiO ₂ ‐Chitosan Adsorbents for Removal of Cadmium and Lead From Water

This work investigated CoFe 2 O 4 @SiO 2 ‐chitosan magnetic nanocomposites functionalized with chitosan, which served as an efficient adsorbent for the separation of trace lead (Pb(II)) and cadmium (Cd(II)) in water. The percentage of contaminants extracted from the solution has been measured through atomic absorption spectroscopy (AAS). Furthermore, the pseudo‐first‐order and pseudo‐second‐order kinetic models, along with the Freundlich and Langmuir isotherm models, were applied to evaluate the kinetic and equilibrium data for metal adsorption on adsorbents. The magnetic adsorbent demonstrated excellent magnetic properties and high Langmuir adsorption capacities of 255.10 mg/g for lead (Pb(II)) and 236.41 mg/g for cadmium (Cd(II)) ions. The second‐order kinetic model and Langmuir adsorption isotherm exhibit the most precise adsorption data match. Results suggested that the coordinative interaction of amino groups in chitosan and metal ions was responsible for the occurrence of chemisorption. The adsorption efficiency after the first cycle for Pb(II) and Cd(II) ions was 93% and 89%, respectively. Furthermore, the adsorbents exhibited outstanding reliability, excellent reusable values, and good application performance, with 82% and 79% for lead (Pb(II)) and cadmium (Cd(II)), respectively, after five cycles of adsorption.