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

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.].