Adsorption and photocatalytic degradation process of oxytetracycline using mesoporous Fe-TiO2 based on high-resolution mass spectrometry

In this study, the adsorption and photocatalytic degradation of oxytetracycline (OTC) were systematically investigated using different metal-doped anatase-phase mesoporous TiO2 nanocatalysts (M−TiO2, M = Fe, Co, Ni, Cr). The results showed that doping with different metals had a significant effect on the ability of TiO2 to adsorb and degrade OTC. Comparing the photoelectric properties of four photocatalysts (Fe-TiO2, Co-TiO2, Ni-TiO2 and Cr-TiO2), it was observed that the mutual synergy between the separation ability of the photogenerated carriers and the adsorption ability of pollutants was the fundamental reason for the excellent photocatalytic performance of Fe-TiO2. The relative intensities of the high-resolution mass spectrometry (HRMS) peaks were used to track and analyse the degradation products of pollutants at different adsorption or light-irradiation times during the photocatalytic process. The ability of the pollutants to undergo dark-state adsorption significantly influenced their degradation paths and products. The possible mechanism of the photocatalytic decomposition of pollutants using Fe-TiO2 along different paths was proposed according to the Fukui function calculation and MS results. To the best of our knowledge, this is the first time that quantitative HRMS results have been used to assess the degradation pathways of pollutants.