Fe-Cu-loaded γ-Al2O3 as an efficient heterogeneous Fenton catalyst for the advanced treatment of petrochemical wastewater

A novel Fe-Cu/γ-Al₂O₃ heterogeneous Fenton catalyst was developed for the degradation of real petrochemical secondary effluent using H₂O₂ under near-neutral pH conditions (6–8). This approach addresses key limitations of traditional Fenton systems, including their narrow pH range and generation of iron sludge. No sludge formation was detected, and Fe/Cu leaching remained below 1 mg/L after nine consecutive reuse cycles, confirming the catalyst's stability and reusability. The catalyst was synthesized via impregnation and calcination, with preparation parameters optimized using a one-factor-at-a-time method. Under optimal conditions (Fe: 0.28 mol/L; Cu: 0.20 mol/L; 500 °C; 7 h), 50.15% TOC removal was achieved using 20 g catalyst and 13.73 mmol/L H₂O₂. Characterization techniques (SEM, BET, XRD, XPS) confirmed the structural features, while EPR and quenching experiments revealed that ·OH and HO₂⁻ were the dominant reactive species. The Fe(III)/Fe(II) and Cu(II)/Cu(I) redox pairs on the catalyst surface were identified as active sites for H₂O₂ activation. This study demonstrates a robust, sludge-free Fenton-like system with practical potential for advanced petrochemical wastewater treatment.