Magnetic enrichment behavior of monodispersed MFe2O4 nanoferrites (M = Mg, Ca, Ni, Co, and Cu)

The magnetic enrichment behavior of monodispersed MFe2O4 (M = Mg, Ca, Ni, Co, and Cu) ferrite nanoparticles with different size (10-130 nm) on the surface of a 15 mm o.d. NdFeB-N40 magnetic rod has been investigated. The materials were synthesized by a modified sol-gel method. They were characterized by XRD, TEM, and VSM. The magnetic field of the rod was modelled numerically using a finite element analysis software to obtain the input data for the magnitude of magnetic force. Three adsorption models can be used to describe the enrichment mechanism of ferrite nanoparticle depending on the magnetic permeability: (i) Freundlich adsorption model at low magnetic permeability ( < 10 mu emu/Oe) which leads to the enrichment percentage below 50%, (ii) mixed (multilayer) adsorption model at intermediate permeability (10-50 mu emu/Oe), and (iii) a monolayer adsorption at high permeability ( > 100 mu emu/Oe) leading to the enrichment percentage above 90%.