Hydrothermal synthesis of nanostructured iron oxide visible-light photocatalysts from mill scales

Nanostructured Fe2 O3 visible light photocatalysts with different morphologies were successfully synthesized from mill scales using a hydrothermal method. The leaching efficiency of mill scales was discussed by changing the leaching parameters such as hydrochloric acid concentration, liquid-to-solid ratio and reaction time. The dependences of the morphology and photocatalytic property of as-prepared Fe₂O₃ on the purity of leachates were investigated during hydrothermal synthesis. When the reflux reaction between 8 g of iron scales and 150 mL of 3 mol·L^-1 HCl proceeds at 100℃ for 2 h, the leaching rate of iron scales reaches about 93% and the purity of leachates is high. It is indicated that impurity ions in the leachates play an important role in controlling the microstructure and the crystal growth direction of the nanostructured Fe₂O₃. Moreover, the nanostructured Fe₂O₃ has a better photocatalytic property, and it can degrade rhodamine B solution up to about 87% after 60 min under visible light illumination.