Adsorptive performance of modified CoFe2O4@SiO2 magnetic nanoparticles for removal of toxic Cd (II) from aqueous solutions and study their kinetics, isotherm, thermodynamic, and reusability

In this work, the adsorption capacities of CoFe2O4 magnetic nanoparticles were enhanced successfully by modifying coated-CoFe2O4@SiO2 magnetic nanoparticles with sodium dodecyl sulfate and dithiooxamide and became CoFe2O4@SiO2–SDS–DTO magnetic nanoparticles. The CoFe2O4@SiO2–SDS–DTO magnetic nanoparticles were characterized using FESEM, TEM, VSM, BET, TG-DTG, and FTIR techniques. The CoFe2O4@SiO2–SDS–DTO magnetic nanoparticles were used as an adsorbent for the removal of cadmium ions in the aqueous solution. The CoFe2O4@SiO2–SDS–DTO magnetic nanoparticles demonstrated high capability to remove cadmium ions in the aqueous solution under optimum conditions, such as pH = 6; dosage = 50 mg; time = 30 min; T = 298 K. Furthermore, the Langmuir isotherm model was found to be more suitable for describing the adsorption of cadmium ions onto CoFe2O4@SiO2–SDS–DTO magnetic nanoparticles compared to the Freundlich and Temkin isotherm models. The optimum adsorption capacity for CoFe2O4@SiO2–SDS–DTO magnetic nanoparticles at 298 K was observed to be 350.08 mg/g. The thermodynamic studies indicated that the adsorption of cadmium ions onto CoFe2O4@SiO2–SDS–DTO magnetic nanoparticles was a spontaneous process. Moreover, the kinetic studies were performed on the adsorption of cadmium ions onto CoFe2O4@SiO2–SDS–DTO magnetic nanoparticles, and the experimental data demonstrated a proper fit with the pseudo-second order model, which confirms the adsorption capacity of the pseudo-second-order model.