Preparation and characterization of nitrogen-doped TiO 2 /diatomite integrated photocatalytic pellet for the adsorption-degradation of tetracycline hydrochloride using visible light

Abstract Pharmaceutical wastes, such as antibiotics, have been successfully degradated by TiO2 under UV light irradiation. Yet, similar work has seldom been done by visible light responsive catalysts. In this work, we prepared N doped TiO2/diatomite integrated photocatalytic pellet (N-IPP), and evaluated its photoactivity by degradating tetracycline hydrochloride (TC) solution. According to the degradation results, optimal experimental and preparation conditions were determined. Besides, the effects of inorganic ions were also investigated: Ca2+, Mg2+, NO3−, SO42− and PO43−. According to BET results, the specific surface area of N-IPP pellet was similar to that of N-TiO2/diatomite powder. SEM and TEM images showed that, the hierarchical porous structure of diatomite helped TiO2 nanoparticles disperse well on its surface and prevented their agglomeration. XRD and XPS analysis revealed that, the formation of Si–O–Ti bond and N dopant restrained the crystal growth of TiO2. Various intermediates generated during degradation process were illustrated, and active species were determined using scavengers, then we concluded the degradation pathway and mechanism of N-IPP. Moreover, N-IPP exhibited good reusability and could be easily filtrated from the reactor.