Photocatalytic degradation of Reactive Black 5 with TiO₂-coated magnetic nanoparticles

A core-shell TiO2-coated magnetic nanomaterial, Fe 3O4@SiO2@TiO2, was prepared, characterized and tested as photocatalyst in the degradation of Reactive Black 5 (RB5) dye by a UV-photocatalytic path. For comparison, two reference materials were also evaluated as photocatalysts in the same reaction: as-prepared non-magnetic TiO2 and TiO2 from Evonik Degussa Company (P25). TEM characterization confirmed the core-shell structure of the Fe 3O4@SiO2@TiO2 nanocomposite, while SEM micrographs revealed that the particles presented a spherical morphology with sizes ranging from 140 to 160 nm. FTIR and XRD data confirmed the presence of magnetite (Fe3O4) cores, silica and anatase in the magnetic nanomaterial. The Fe3O4@SiO2@TiO 2 photocatalyst in combination with UV irradiation led to a RB5 degradation of 91% after 60 min, which was very similar to the values achieved with the as-prepared TiO2 (93%) and with P25 (97%). Furthermore, the magnetic nanocatalyst was efficiently separated from the reaction medium by magnetic decantation and could be reused three times with no decrease of the photocatalytic performance.