Waste‐Derived ZnFe ₂ O ₄ Composite Catalyst for Application in Organic Pollutant Degradation

This study utilized zinc‐rich pickling wastewater (Fe/Zn molar ratio = 1.98 ± 0.05) and zinc‐containing sludge as raw materials to successfully prepare waste‐derived ZnFe 2 O 4 (ZFO) and ZnO nanomaterials through hydrothermal and pyrolysis methods, respectively. Subsequently, a ZnFe 2 O 4 ‐ZnO (ZFZ) composite catalyst was synthesized via a co‐precipitation method for activating peroxymonosulfate (PMS) to degrade organic dye pollutants. The construction of a heterojunction by incorporating ZnO significantly enhanced the catalytic performance of the ZFZ1:1 composite, achieving 99.2% Rh6G degradation within 12 min. Photoelectrochemical tests confirmed that the introduction of ZnO effectively facilitated electron transfer and radical generation. Batch‐to‐batch reproducibility tests showed consistent activity (98.5%–99.3% Rh6G removal over five batches) Recycling experiments demonstrated that the ZFZ1:1 composite maintained a 91.6% degradation efficiency after five consecutive cycles, with heavy metal leaching concentrations complying with environmental standards.