Oxygen Vacancy Promoted Heterogeneous Fenton-like Degradation of Ofloxacin at pH 3.2-9.0 by Cu Substituted Magnetic FeO@FeOOH Nanocomposite.

To develop an ultraefficient and reusable heterogeneous Fenton-like catalyst at a wide working pH range is a great challenge for its application in practical water treatment. We report an oxygen vacancy promoted heterogeneous Fenton-like reaction mechanism and an unprecedented ofloxacin (OFX) degradation efficiency of Cu doped FeO@FeOOH magnetic nanocomposite. Without the aid of external energy, OFX was always completely removed within 30 min at pH 3.2-9.0. Compared with FeO@FeOOH, the pseudo-first-order reaction constant was enhanced by 10 times due to Cu substitution (9.04/h vs 0.94/h). Based on the X-ray photoelectron spectroscopy (XPS), Raman analysis, and the investigation of HO decomposition, OH generation, pH effect on OFX removal and HO utilization efficiency, the new formed oxygen vacancy from in situ Fe substitution by Cu rather than promoted Fe/Fe cycle was responsible for the ultraefficiency of Cu doped FeO@FeOOH at neutral and even alkaline pHs. Moreover, the catalyst had an excellent long-term stability and could be easily recovered by magnetic separation, which would not cause secondary pollution to treated water.