Photocatalytic degradation of methylene blue dye by TiO2 supported on magnetic core shell (Si@Fe) surface

Abstract

Magnetic photocatalysts were obtained with different TiO2 (Ti) contents supported on the core–shell structure, SiO2@δ-FeOOH, obtaining the the main photocatalysts 30, 50 and 80 Ti/Si@Fe. The characterization performed by DSC and TGA showed that the feroxyhyte undergoes dehydroxylation between 120 and 190 °C and indicated the formation of Fe2O3. The results obtained by XRD confirmed the conversion from δ-FeOOH to γ-Fe2O3 and α-Fe2O3 during the heat treatment performed to support TiO2 P25 in the SiO2@δ-FeOOH composite. The formation of silica on δ-FeOOH was confirmed by ATR analysis and the core–shell structure by TEM images. The efficiency in the separation stage of the photocatalysts from the aqueous medium was evaluated by sedimentation kinetics in the presence of a magnetic field. The results showed that the prepared materials can be quickly and simply separated due to their magnetic property. The efficiency of the magnetic photocatalysts to decolorize methylene blue dye in the presence of UV radiation ranged from 73 to 96% in 120 min of reaction, while the efficiency of the reactions carried out in sunlight ranged from 91 to 97% in just 60 min. These results show that Ti/Si@Fe photocatalysts can be prepared in a simple way, showing high photocatalytic efficiency being easily recovered and reused in other reactions, which generates cost savings.