Enhanced superoxide radical production for ofloxacin removal via persulfate activation with Cu-Fe oxide

Abstract Cu-Fe composite oxides with different Cu:Fe ratios were synthesized by a hydrothermal method and investigated as a heterogeneous catalyst for persulfate activation. The obtained samples exhibited much higher activity than CuFe2O4 for the degradation and mineralization of ofloxacin with persulfate, and the optimized Cu:Fe ratio was 1:1 (CuFe1). The results of catalyst characterization and electron paramagnetic resonance analysis indicate that the activities of the catalysts for ofloxacin degradation and superoxide radical ( O2−) production are highly positively correlated with their redox ability. The removal efficiencies of ofloxacin in the presence of different scavengers further demonstrate that O2− is the dominant reactive species in this process, which is quite different from previous studies. It is suggested that CuFe1 with higher oxidation ability could weaken the S O bond of adsorbed persulfate, thus promoting the decomposition persulfate into O2−. Finally, the possible degradation pathway of ofloxacin was proposed according to the liquid chromatography−mass spectrometry result.