Kinetic sorption study of Cerium (IV) on magnetite nanoparticles

Magnetite nanoparticles (Fe3O4) and humic acid-coated magnetite nanoparticles (Fe3O4/HA) were prepared by co-precipitation method for cerium ions removal from aqueous solution. The success of preparation in nanoscale was confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM image shows that the size of Fe3O4 is around 15 nm and the presence of humic acid reduces the magnetite aggregation and stabilizes the magnetite suspension. Adsorption studies with respect to various process variables such as contact time, pH, and temperature were investigated by batch technique. The sorption kinetics and isotherms of Fe3O4 and Fe3O4/HA for Ce (IV) ions show that the sorption kinetics follow the pseudo-second-order and Langmuir isotherm models for both sorbents. The maximum capacities (Q(max)) of Ce (IV) onto Fe3O4 and Fe3O4/HA were found to be 160 and 280 mg/g, respectively. The thermodynamic parameters (Delta G degrees, Delta H degrees and Delta S degrees) were calculated, and the results revealed that the sorption process of Ce (IV) ions on both Fe3O4 and Fe3O4/HA are spontaneous, endothermic for Fe3O4 and exothermic for Fe3O4/HA.