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

Abstract

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 μemu/Oe) which leads to the enrichment percentage below 50%, (ii) mixed (multilayer) adsorption model at intermediate permeability (10–50 μemu/Oe), and (iii) a monolayer adsorption at high permeability (>100 μemu/Oe) leading to the enrichment percentage above 90%.