A novel recyclable photocatalytic composite TiO2NTs@Bi25FeO40 for tetracycline mineralization

[Display omitted] •The Bi25FeO40 were firmly loaded on TiO2 NTs through a simple hydrothermal method.•TiO2 NTs@Bi25FeO40 heterojunctions exhibited the excellent photocatalytic activity in the degradation of TC.•The photocatalytic mechanism of TiO2 NTs@Bi25FeO40 heterojunctions was explored.•The composites can be recovered directly from water without causing secondary pollution. Titanium dioxide nanotubes (TiO2NTs) are prepared by anodizing Ti substrates, which is a good solution to the problem that powdered materials are more difficult to recycle. Hence, a novel recyclable TiO2NTs@Bi25FeO40 (TiO2/BFO) photocatalyst was prepared by anodic oxidation combined with hydrothermal deposition. The photocatalytic ability of TiO2NTs prepared at different factors and Bi25FeO40 compound was evaluated. The TiO2/BFO showed the optimal photocatalytic efficiency, which the removal ratio of tetracycline hydrochloride (TC-HCl) higher than that of TiO2NTs under visible-light irradiation. UV–vis diffuse reflectance spectra (DRS) analysis proved that the band gap of TiO2/BFO was narrower than that of TiO2NTs. The narrow band gap of TiO2/BFO results in a broadening of its light absorption region. Meanwhile, the combination of free radical quenching experiments and EPR measurement showed that ·O2− was the main active radical in the photocatalytic process, and the presence of Bi25FeO40 effectively promoted the generation and transfer of electrons. Mechanistic analysis showed that a unique II-type heterojunction electron transfer structure was formed between TiO2NTs and Bi25FeO40, which promoted the photogenerated electron-hole separation and improved the photocatalytic oxidation activity. The preparation of TiO2/BFO provided a new strategy for synthesizing more efficient and environmentally friendly photocatalyst.