Tuning the intrinsic catalytic sites of magnetite to concurrently enhance the reduction of HO and O: Mechanism analysis and application potential evaluation.

Heterogeneous Fenton-like process based on HO activation has been widely tested for water purification, but its application still faces some challenges such as the use of high doses of chemicals (including catalysts and HO). Herein, a facile co-precipitation method was utilized for small-scale production (∼50 g) of oxygen vacancies (OVs)-containing FeO (V-FeO) for HO activation. Experimental and theoretical results collaboratively verified that HO adsorbed on the Fe site of FeO tended to lose electrons and generate O. While the localized electron from OVs of V-FeO could assist in donating electrons to HO adsorbed on OVs sites, this allowed more HO to be activated to OH, which was 3.5 folds higher than FeO/HO system. Moreover, the OVs sites promoted dissolved oxygen activation and decreased the quenching of O by Fe(III), thus promoting the generation of O. Consequently, the fabricated V-FeO achieved much higher oxytetracycline (OTC) degradation rate (91.6%) than FeO (35.4%) at a low catalyst (50 mg/L) and HO dosage (2 mmol/L). Importantly, further integration of V-FeO into fixed-bed Fenton-like reactor could effectively eliminate OTC (>80%) and chemical oxygen demand (COD) (21.3%∼50%) within the running period. This study provides promising strategies for enhancing the HO utilization of Fe mineral.