Activation of Peroxydisulfate by Natural Titanomagnetite for Atrazine Removal via Free Radicals and High-Valent Iron-oxo Species

Publication date: Available online 21 January 2020Source: Chemical Engineering JournalAuthor(s): Leiduo Lai, Hongyu Zhou, Heng Zhang, Zhimin Ao, Zhicheng Pan, Qixuan Chen, Zhaokun Xiong, Gang Yao, Bo LaiAbstractNatural titanomagnetite, a potential catalyst, was used as a peroxydisulfate (PDS) activator for the removal of atrazine (ATZ) in water for the first time. The surface ≡Fe(Ⅱ) and ≡Fe(III) of titanomagnetite was certified as the active components by XRD and XPS analyses. ATZ removal showed a strong dependence on the titanomagnetite concentration (0-10 g/L), PDS concentration (0-10 mM) and the initial pH (3.0-11.0) under experimental conditions. Quite different from the traditional heterogeneous PDS-activated processes, titanomagnetite/PDS system could remove ATZ via both radical and nonradical pathways. Here, both free radicals (SO4•- and HO•) and high-valent iron-oxo species were proved to be the main reactive oxygen species (ROS) by quenching experiments, EPR tests and UPLC/ESI−MS/MS analysis. The high-valent iron-oxo species, ≡FeⅣ=O and ≡FeⅤ=O, could be generated from the ≡Fe(Ⅱ) and ≡Fe(III) of the titanomagnetite via a nonradical pathway. In addition, the generated passivation layer after reaction was found via XPS analysis, which could block the function of ≡Fe(Ⅱ) and ≡Fe(III), hindering the generation of ROS. However, the catalytic activity of titanomagnetite could recover if passivation layer was removed by ultrasonic cleaning. Fin...

Source: Chemical Engineering Journal - January 21, 2020 Category: Chemistry Source Type: research