Abstract

Magnetic materials have received much attention due to their use in various applications such as biomedical, waste water treatment, photocatalytic, and electrocatalytic applications. Among the magnetic materials, Fe3O4 magnetic nanoparticles (MNPs) are the finest choice, due to their easy preparation process and flexible magnetic characteristics with adjustable morphology and size. Surface modifications of Fe3O4 MNPs with suitable surface modifier are necessary to utilize the hybrid materials for any specific required applications. The selection of surface modifier is important, as it is having a major role for the specific applications. The MNPs with higher saturation magnetization are essential for any magnetic field-assisted applications even with the surface modifier. In this chapter, the progresses on the surface modifications of Fe3O4 for the potential use in the heavy metal ion and radioactive toxin ion removal from water solutions are discussed. The possibility for the development of highly magnetic surface-modified MNPs of Fe–Fe3O4–Prussian blue system as a recoverable adsorbent is proposed.