Synthesis of SrFe12O19/SiO2/TiO2 composites with core/shell/shell nano-structure and evaluation of their photo-catalytic efficiency for degradation of methylene blue

The SrFe₁₂O₁₉/SiO₂/TiO₂ nanostructures with hard magnetic core were successfully synthesized through the facile and efficient wet chemical processes. At first, nanocrystalline strontium hexaferrite (SrFe₁₂O₁₉) powder was prepared using a new co-precipitation route in ethanol/water media. In the next step, SrFe₁₂O₁₉/SiO₂ composites were produced by well-known Stöber method using tetraethyl orthosilicate as precursor. Finally titania was coated on SrFe₁₂O₁₉/SiO₂ composite particles using titanium n-butoxide precursor. The core/shell/shell nanostructures have been characterized by means of X-ray diffraction, vibrating sample magnetometer, Fourier transform infrared spectra, field emission scanning electron microscopy, and transmission electron microscopy equipped with an energy-dispersive X-ray spectroscopy detector. The catalytic activity of SrFe₁₂O₁₉/SiO₂/TiO₂ composites has been investigated in the degradation of methylene blue dye under UV illumination. The results indicated that the obtained SrFe₁₂O₁₉/SiO₂/TiO₂ composite has photo-catalytic properties and can be retrieved by magnetic separation. The photo-degradation of methylene blue dye was about 80% in the presence of photo-catalyst powder at irradiation time of 180 min. Recycled composite particles could be used again.