Catalytic ozonation mechanisms of Norfloxacin using Cu–CuFe2O4

As an easily recoverable, environmentally friendly and cost-effective catalyst, CuFe2O4 is a promising candidate for the catalytic ozonation of antibiotics in wastewater. However, its catalytic activity is restricted due to its limited active sites and low electron transfer efficiency. In this study, cetyl trimethyl ammonium bromide (CTAB) and Cu0 were doped with CuFe2O4 to introduce more OV, providing more active sites and improving electron transfer efficiency. Experimental results show that the optimum removal efficiency of the catalytic ozonation of Norfloxacin (NOR, a widely used antibiotic) using CTAB doped with Cu–CuFe2O4 as the catalyst is 81.58% with a first-order reaction kinetics constant of 0.03967 min-1. The associated O3 and catalyst dosages are 2.72 mg·L-1 and 0.1 g·L-1, respectively, which are 1.63 times and 2.22 times higher than those in an equivalent O3 system. OV can provide generation sites for surface hydroxyl groups and trigger ·O2− and 1O2 as the main active oxygen species. The synergistic redox cycles of Fe2+/Fe3+ and Cu0/Cu2+ accelerate electron transfer efficiency. The possible degradation pathways of NOR are identified as defluorination, naphthyridine ring-opening and piperazine ring-opening. In summary, this work proposes a new strategy for the modification of CuFe2O4 catalysts and provides new insights into the catalytic ozonation mechanisms for NOR removal.