Enhanced heterogeneous photo-Fenton catalytic degradation of tetracycline over yCeO2/Fh composites: Performance, degradation pathways, Fe2+ regeneration and mechanism

Natural ferrihydrites (Fh) can activate H2O2 to produce reactive oxygen species in Fenton-like system, while the inefficient Fe2+ regeneration limited its application. A novel heterogeneous photo-Fenton catalyst with enhanced organics degradation activity was developed by decorating bio-template synthesized ceria (yCeO(2)) on Fh (yCeO(2)/Fh). Various characterizations (i.e., XRD, SEM-EDS, FT-IR, XPS and DRS) for the prepared yCeO(2)/Fh verified the location of yCeO(2) on Fh surface and the semiconductive properties of yCeO(2). Different influential reaction parameters were thoroughly explored and the 15-yCeO(2) /Fh composite with 15% mass ratio of yCeO(2) showed significantly enhanced degradation rate (98.7%) and mineralization rate (70.1%) of tetracycline (TC) than pure Fh. Three plausible TC degradation pathways were proposed on account of the emerging intermediates identified by LC-MS. The co-existing anions that mildly inhibited TC catalytic degradation have closely relation to TC removal efficiency in tap water and river water. Mechanism analyses confirmed the appropriate yCeO(2) introduction accelerated Fe2+ and Ce3+ regeneration with assistant of photo-electrons and Ce4+/Ce3+ circulation, which further facilitated H2O2 consumption and resulted in higher TC degradation efficiency. Radicals trapping experiments and electron spin resonance measurement proved that (OH)-O-center dot played critical contribution in organics degradation. When the catalysts were employed to other types pollutants such as Tetrabromobisphenol A, Rhodamine B and 2,4-dichlorophenol, yCeO(2)/Fh composite still showed excellent catalytic activity. Therefore, this study provides insight into the yCeO(2) action in minerals/photo-Fenton catalytic system and further broadens the development of visible-light-response catalysts application in Fenton-like system.