A novel synthesis method for TiO₂ particles with magnetic Fe₃O₄ cores

TiO₂@(AC/Fe₃O₄) (AC is activated carbon) was prepared by using AC and Fe₃O₄ as joint support. The morphological features, crystal structure, and magnetism of the final product were characterized. The results indicate that TiO₂ particles formed on the surface of AC and Fe₃O₄; the sizes of TiO₂ and Fe₃O₄ were 0.5 and 0.7 μm respectively, and that of AC fell within a wide range. The highly crystalline cubic structures of the TiO₂ particles was in accord with the standard X-ray diffractometry spectrum of magnetite and anatase. The maximum saturation magnetization of TiO₂@(AC/Fe₃O₄) was 75 emu g⁻¹, which was enough to support magnetic recovery. The rate of methylene blue (MB) removal photocatalyzed by TiO₂@(AC/Fe₃O₄) was higher by 50% than that achieved with AC/Fe₃O₄ photocatalysis, and similar to that achieved with TiO₂@AC. The removal rate (k_obs) decreased drastically from 1.77 × 10⁻² to 9.36 × 10⁻³min⁻¹ when the initial concentration of MB solution increased from 2.0 to 5.0 mg L⁻¹. The k_obs value increased from 9.41 × 10⁻³ to 1.34 × 10⁻²min⁻¹ with increasing photocatalyst dosage from 0.2 to 1.0 g, then slightly decreased to 1.33 × 10⁻²min⁻¹ at 2.0 g dosage.