BACKGROUND: Iron (Fe)-copper (Cu) bimetallic catalysts such as CuFe 2 O 4 , CuFeO 2 and CuO/Fe 3 O 4 have been widely applied in persulfate oxidization process. Among these catalysts, CuFe 2 O 4 has shown excellent performance in catalyzing peroxymonosulfate. However, because the catalytic effect of CuFe 2 O 4 on persulfate (PS) is not obvious, the application of CuFe 2 O 4 to activate persulfate has been investigated only rarely. Hence, structural modification has been applied in order to improve the catalytic activity of CuFe 2 O 4 on persulfate.RESULT: In this study, Oxygen (O)-deficient CuFe 2 O 4 was synthesized via the hydrogen reduction method and first used to activate PS for degrading acetaminophen (APAP) in aqueous solution with low catalyst concentration of 0.3 g L −1 . Results reveal that high-concentration APAP (100 mg L −1 ) could be efficiently removed by O-deficient CuFe 2 O 4 -activated PS, and 91% removal rate could be reached in 60 min using 0.8 g L −1 PS and 0.3 g L −1 catalyst under unadjusted pH. Dissolved O 2 and Cl − showed inhibitory effects on the degradation process. Radical scavenger experiments, in which methanol, tert-butyl alcohol (TBA) and nitrobenzene (NB) were used as radical trappers, indicated that SO 4 − and OH were the active radicals in the reaction, but the main radical was SO 4 − . Oxygen-deficient CuFe 2 O 4 showed strong reduction ability and could activate PS efficiently, and the electron transfer capability was remarkably enhanced after this structural modification. CONCLUSIONS: Results indicated that compared to the pristine crystal, the catalytic activity of CuFe 2 O 4 could be improved through structural modification. Additionally, the structurally modified catalyst showed high potential to treat wastewater with high antibiotic content under mild conditions. Romero A. Oxidation of priority and emerging pollutants with persulfate activated by iron: effect of iron valence and particle size. Chem Eng J 318:197-205 (2017).J Chem Technol Biotechnol 2019; 94: 785-794