Novel cobalt-doped CuFe2O4 spinel catalyst for enhanced peroxymonosulfate activation to achieve rapid degradation of tetracycline hydrochloride: Dominant roles of O2- and 1O2 in the oxidation process

Abstract

Heterogeneous peroxymonosulfate (PMS) catalysis is a promising method for water pollution treatment. CuFe₂O₄ spinel can activate PMS, but its application is limited by its tendency to agglomerate and its low-mass transfer efficiency. In this study, a cobalt-doped CuFe₂O₄ (CuFeCoO₄, CFCo-1) was successfully synthesized, achieving a degradation efficiency of 98.36 % for tetracycline hydrochloride (TCH) within 21 min, with a high degradation rate corresponding to a kinetic constant of 0.2041 min⁻¹. CFCo-1 demonstrated strong resistance to interference from inorganic ions and organic compounds. It maintained over 90 % TCH removal efficiency with negligible leaching of metal ions after five cycles, indicating that the catalyst had strong cyclic stability. Mechanistic analysis revealed that cobalt doping improved the electron transfer efficiency of the catalyst, enabling CFCo-1 to activate PMS and degrade the pollutant through both radical (OH, SO₄^- and O₂^-) and non-radical (¹O₂) pathways, with O₂^- and ¹O₂ being the dominant species. The potential degradation pathways of TCH were proposed based on theoretical calculation and the identification of degradation products. In conclusion, cobalt doping is an effective strategy for enhancing the catalytic performance of spinel for efficient degradation of pollutants in water.