Effective Removal of Tetracycline by Using Bio-Templated Synthesis of TiO2/Fe3O4 Heterojunctions as a UV–Fenton Catalyst

Abstract

Novel maize-straw-templated TiO2/Fe3O4 hierarchical porous composites were synthesized by high-temperature calcination followed by a hydrothermal process. The composites were demonstrated to be efficient heterogeneous catalysts for the UV–Fenton-like degradation of TC. The results show that the as-prepared TiO2/Fe3O4 catalysts retain the original pore morphology of the maize-straw material, and a large amount of Fe3O4 particles are attached to the TiO2 surfaces. The as-prepared TiO2/Fe3O4 heterojunctions have abundant interfacial boundaries, which greatly improve the migration of photoexcited charges across different components. Consequently, in the UV–Fenton system, the TiO2/Fe3O4 catalysts exhibit significant activity towards the degradation of TC (50 mg/L) in a wide pH range. In particular, a maximum mineralization and TC removal of 98% is achieved within 60 min at pH 7.0, which is much higher than that of traditional Fe3O4-based UV–Fenton (81%) and TiO2 photocatalysis (23%). The enhanced degradation and mineralization of tetracycline is attributed to the efficient reduction of Fe3+ to Fe2+ by photo-generated electrons from the TiO2 skeleton of the TiO2/Fe3O4 heterojunction. Graphical Abstract: [Figure not available: see fulltext.].