Robust Adsorption and Persulfate-Based Degradation of Doxycycline by Oxygen Vacancy-Rich Copper-Iron Oxides Prepared through a Mechanochemical Route

Persulfate-based advanced oxidation over heterogeneous catalysts is an effective approach to degrade organic pollutants, and prior adsorption of the pollutants on the catalysts is an essential step. In this study, CuO/Fe2O3 (CF) composite materials with a robust adsorption capacity and catalytic activity toward organic pollutants were prepared using a green mechanochemical route. The raw CuO and α-Fe2O3 present in the materials were transformed into CuFe oxide catalysts with abundant oxygen vacancies during the mechanochemical reaction. The maximum adsorption capacity of CF composite materials for doxycycline was as high as 200 mg/g. First-principles density functional theory calculations revealed that the CF composite material had a very strong ability to attract and decompose persulfate and produced more reactive oxygen species, mainly 1O2, O2 –•, and SO4 •–. Doxycycline was decomposed into CO2 and H2O through three possible pathways. The efficiency of total organic carbon (TOC) removal by the CF/persulfate system was up to 90%. Our study provided a facile synthetic method (as it involved no organic solvent, was viable for use at an industrial scale, and generated no wastewater) for the preparation of catalysts with excellent performance to decontaminate wastewater.