Defect-enriched ilmenite-type catalyst derived from titanium dioxide slag for peroxymonosulfate activation in efficient tetracycline removal

The removal of antibiotics from wastewater is crucial, and the activating of PMS is an effective method for this purpose. To design a suitable catalyst, a defect-enriched ilmenite-type catalyst (D-FeTiO3/C) was constructed using titanium dioxide slag as a precursor for peroxymonosulfate (PMS) activation to remove tetracycline (TC). The obtained D-FeTiO3/C catalyst showed excellent activation ability towards PMS, achieving a TC degradation efficiency over 90% within 120 min. The introduction of oxygen vacancies by ball milling significantly improved the activation ability. The effects of operational conditions on TC removal were systematically investigated in the D-FeTiO3/C/PMS system. The primary active species in the D-FeTiO3/C/PMS system were non-free radicals of singlet oxygen, although free radical species also contributed to TC degradation. Degradation pathways for TC were proposed, and most of the intermediates were non-toxic by-products. This study developed a promising method to recycle solid slag wastes and effectively treat antibiotics in water environments.