Nanosized Fe3O4/SiO2 core-shells fabricated from natural sands, magnetic properties, and their application for dye adsorption

Abstract

This work presents Fe3O4/SiO2 core-shell fabrication. Silica (SiO2) nanoparticles (NPs) were prepared from silica sand using a continuous method, and Fe3O4 NPs were prepared from iron sand using the co-precipitation route. For Fe3O4/SiO2 core-shell fabrication, we used the wet mixing method, where the composition of Fe3O4 and SiO2 NPs was varied, and polyethylene glycol (PEG) was used as a binder. With an in-situ technique, tetraethyl orthosilicate (TEOS) was used as the SiO2 precursor to coat the surface of the Fe3O4 NPs and the mass ratio of SiO2 and Fe3O4 NPs was modified by varying the composition of the TEOS. The samples were characterized as follows: the structure, functional groups, particle size, morphology, and the magnetic property of Fe3O4/SiO2 was characterized via X-ray diffraction, energy dispersive X-ray, Fourier transform infrared, scanning electron microscopy, and vibrating sample magnetometer, respectively, and porosity analysis was conducted. The Fe3O4/SiO2 composites were successfully synthesized using wet mixing and in situ methods. Specifically, the diffraction peaks show PEG (2θ19° and 23°) for samples prepared using the wet mixing technique. The presence of PEG in the Fe3O4/SiO2 composites reduced the saturation magnetization of the Fe3O4 NPs significantly from 29.5 to 9.0 emu/g when synthesized using the wet mixing method, and from 29.5 to 19.8 emu/g when synthesized using in the situ method. Furthermore, the increasing SiO2 NPs composition reduced the shell wall thickness significantly and enhanced the adsorption porosity of the Fe3O4/SiO2 core-shells. The higher SiO2 content led to a decrease in the porous volume of the Fe3O4/SiO2 core-shells.

Keywords

• fe3o4/sio2
• magnetic nanoparticle
• dye color
• wastewater