Prussian blue analogue derived magnetic Cu-Fe oxide as a recyclable photo-Fenton catalyst for the efficient removal of sulfamethazine at near neutral pH values

The presence of antibiotics in aquatic environments has attracted global concern. Heterogeneous photo-Fenton process is an attractive yet challenging method for antibiotics degradation, especially when such a process can be operated at neutral pH values. In this work, a new magnetic Cu-Fe oxide (CuFeO) was developed as the heterogeneous photo-Fenton catalyst through a facile two-step method. The obtained CuFeO particles were found to be more efficient to activate H2O2 into radicals (% OH and center dot O-2(-)) than Cu-Fe Prussian blue analogue (Cu-Fe PBA, the precursor) at near neutral conditions. The removal rate of sulfamethazine (SMZ) in CuFeO/H2O2/Vis system was much higher than those in CuO/H2O2/Vis and Fe3O4/H2O2/Vis systems. It was observed that nearly complete removal of SMZ from ultrapure water, river water and tap water can be achieved in 30 min in CuFeO/H2O2/Vis system. The influence of different process parameters on the SMZ degradation efficiency was then examined and the catalytic stability of CuFeO was also tested. The SMZ degradation intermediates during the process were analyzed and the degradation pathway was proposed based on LC-MS results. The mechanisms for H2O2 activation were studied by X-ray photoelectron spectrum analysis, radical scavenging and electron spin-trapping experiments. It is suggested that the synergistic effect among photo-induced electrons, Cu and Fe in CuFeO exhibits excellent performance in the catalytic activation of H2O2. This work is expected to provide useful information for the design and synthesis of bimetallic oxide for heterogeneous photo-Fenton reactions.