Effect of Doping on the Magnetic and Sorption Properties of Cobalt-Ferrite Nanoparticles

The use of magnetic nanoparticles as sorbents for wastewater treatment in various industries can improve the efficiency of this process and reduce the impact of humans on the environment. Therefore, the development of a cost-effective method for the preparation of magnetic nanoparticles with optimal physical–chemical properties, especially high saturation magnetization, is a crucial task in current research. In this study, we use the sol–gel-citrate self-combustion method to synthesize a series of spinel ferrite magnetic nanoparticles with different chemical compositions. A set of cobalt-ferrite nanoparticles with the partial substitution of cobalt by zinc and manganese and iron by aluminum is obtained. Among the investigated samples, the zinc-doped cobalt-ferrite nanoparticles show the highest saturation magnetization of 88 A m²/kg at room temperature. Surface modification of the synthesized materials with polyethylene glycol and sodium dodecyl sulphate can improve their colloidal stability and as a consequence increase their sorption capacity.