Nano Fe3-Cu O4 as the heterogeneous catalyst in an advanced oxidation process for excellent peroxymonosulfate activation toward climbazole degradation

Climbazole (CBZ) is an emerging recalcitrant contaminant in wastewater, which has severe toxic effects on aquatic organisms. In this study, the monodispersed Fe3-xCuxO4 nanoparticles were fabricated and used as the heterogeneous catalyst for activating peroxymonosulfate (PMS) toward the degradation of CBZ in aqueous solutions. The results revealed that Cu incorporation in magnetite led to a larger surface area, more reductive ions, and oxygen vacancies on the surface, which effectively improved the catalytic efficiency. For a wide range of pH values (2.2–11.0), the optimized Fe2.31Cu0.69O4 achieved the most excellent efficiency and stability in terms of activating PMS toward CBZ degradation. Based on the detections of electron paramagnetic resonance spectroscopy (ESR) and radical scavenger tests, sulfate radicals (SO4•−) were identified as the main active species during the CBZ degradation process. The possible mechanisms whereby Cu enhances the electron transfer and the generation of superoxide radicals (O2•–) during the activation process of PMS by Fe3-xCuxO4 were proposed. Ten degraded products produced from CBZ through the hydroxylation, dechlorination, ether chain cleavage, and dealkylation pathways were identified. Most of the byproducts’ acute and chronic toxicities were reduced to a much lower level than that of CBZ. The obtained results provide an avenue for rationally constructing and developing a catalyst for the efficient treatment of azole fungicides in wastewater.