Synergetic effect of photocatalysis and peroxymonosulfate activation by CoTiO3/SBA-15, NiTiO3/SBA-15 and Fe2TiO5/SBA-15 for efficient photocatalytic removal of oxytetracycline hydrochloride

Abstract

Nanosized CoTiO₃, NiTiO₃ and Fe₂TiO₅ photocatalysts were synthesized by a simple sol–gel method successfully. However, they showed lower photocatalytic activity for the degradation of oxytetracycline hydrochloride under visible light irradiation. After the CoTiO₃, NiTiO₃ and Fe₂TiO₅ nanoparticles were loaded in the SBA-15 channels, the photocatalytic activity was enhanced obviously. In order to further enhance the removal efficiency of CoTiO₃/SBA-15, NiTiO₃/SBA-15 and Fe₂TiO₅/SBA-15, they were used to activate peroxymonosulfate under visible light irradiation. In particular, CoTiO₃/SBA-15 could completely photodegrade oxytetracycline hydrochloride with the assistance of peroxymonosulfate in an hour. The influencing factors on activating peroxymonosulfate to degrade oxytetracycline hydrochloride were investigated in detail. In addition, the electron transfer and peroxymonosulfate activation mechanism for the efficient improvement in the photocatalytic performance were also proposed and proved by radical quenching experiments, electron spin resonance analysis, X-ray photoelectron spectroscopy, transient photocurrent responses and cyclic voltammetry. It was found that the combined activation effects of photogenerated electrons and transition metals on peroxymonosulfate to produce sulfate radicals could enhance the degradation efficiency obviously. This study could provide a new way for the synergetic effect of photocatalysis and peroxymonosulfate activation by transition metal to be used for efficient photocatalytic degradation in the field of antibiotic removal.