Efficient periodate activation by chalcopyrite for levofloxacin hydrochloride degradation: Effects of sulfur species and dominant pathways of reactive oxygen species

In this study, chalcopyrite (CuFeS2) was synthesized, characterized, and used to activate periodate (PI), and the mechanism of levofloxacin hydrochloride (LVF) removal at a neutral pH was elucidated. LVF removal was directly related to its concentration and that of PI, CuFeS2 dosage, and pH. More than 90 % of 10 mu M LVF was removed within 30 min using the CuFeS2/PI system, and the apparent rate constant (kobs) was 7.85-fold higher than that of an FeS/PI system. Electron paramagnetic resonance spectroscopy, quenching studies, and quantitative analysis revealed the roles of different reactive oxygen species in LVF removal and their dominant pathways. O-2(center dot-) was generated during the cycling of metal species and played a major role in LVF degradation, as the pollutant structure contains N-based heterocycles, F and carboxyl groups, etc. The surface-bound Fe(II) represented the dominant active sites for PI activation, and the reductive S species and Cu(I)-Fe(III) interaction could enhance the regeneration of the Fe(II) active sites. Based on the results of ultra-high-performance liquid chromatography-mass spectrometry and density functional theory calculations, the intermediates of LVF were identified, and possible pathways were proposed. In addition, IO4- was transformed into IO3- without the generation of undesired iodine species (HOI, I-2(,) and I-3(-)). Therefore, this study could provide an effective method based on the CuFeS2/PI system for use in fluoroquinolone antibiotic removal.