Synergistic Cu–Fe interactions in CuO-Fe3O4 catalysts for high-activity Fenton-like degradation of oxytetracycline in water

Abstract

BACKGROUND

The synthesis, characterization and performance evaluation of bimetallic CuO-Fe₃O₄ catalysts in heterogeneous Fenton-like degradation of oxytetracycline (OTC) in water was attempted. Influences of different catalyst compositions on the reaction behaviors were specifically elucidated.

RESULTS

By varying the Cu/Fe molar ratio, CuO-Fe₃O₄ (2/5) was identified as the most effective catalyst, achieving near complete OTC and COD removal within 60 min. Its superior activity resulted from an optimal CuFe balance that enhanced metal dispersion, interaction, and •OH radical generation. The catalyst exhibited high surface area, narrow pore distribution, and minimal Fe leaching (~0.28 mg L⁻¹), maintaining stable performance over five reuse cycles with negligible structural degradation. Calcination at 400 °C further improved activity, offering the best balance of surface reactivity, adsorption, and stability, while under- or over-calcination (350 °C or 600 °C) reduced efficiency due to particle agglomeration leading to limited •OH production. Reaction parameters such as catalyst dosage, H₂O₂ concentration, pH, and OTC loading significantly affected degradation. Optimum conditions were pH 3.0, 0.5 g L⁻¹ catalyst, and 60 mg L⁻¹ H₂O₂. Higher OTC concentrations or excess catalyst reduced efficiency through saturation or radical scavenging.

CONCLUSION

The enhanced catalytic activity arose from synergistic CuFe interactions that promoted •OH generation rather than surface area alone. Owing to its high activity, stability, low metal leaching, and reusability, the CuO-Fe₃O₄ (2/5) catalyst shows strong potential for large-scale water treatment and degradation of organic pollutants under acidic conditions. © 2026 Society of Chemical Industry (SCI).